Rocket furnace drawings calculations. Independent production of a rocket-type furnace. Video: an example of building a rocket stove with a warm stove bench

Content

Portable and stationary rocket stoves (reactive) have proven to be practical, energy efficient devices. The heating and cooking units got their name because of the characteristic roar, reminiscent of the sound of a jet engine - it is heard when excess air enters the furnace. Operating in the standard operating mode, the stove does not disturb the acoustic comfort in the room.

Homemade rocket stoves

Reactive Furnace Features

The first furnace of this type was created for use in the field - a unit was needed for fast food food and heating, and designed for operation in conditions of fuel shortage. The developers managed to find a solution that made it possible to manufacture a compact solid fuel stove with high efficiency.

Further modifications of the unit led to the invention of a stationary stove with a heated bed. Unlike the usual Russian stove, rocket stoves are not bulky and easier to make on your own. The heat generator is able to work on one tab of fuel for about 6 hours, while the stationary structure, for the construction of which adobe plaster is used, gives off the accumulated heat for half a day after the firewood burns out.

Stationary design rocket oven with a stove bench keeps heat for about 6 hours on one tab

Design advantages

The jet furnace is in growing demand as it is a non-volatile heat source that:

• easy to install - a primitive version of the rocket stove is assembled from improvised materials in half an hour;
• works efficiently even on fuels with low calorific value – raw firewood, thin branches, chips, bark, etc.;
• provides heating and allows cooking;
• completely burns fuel with afterburning of wood gas, which minimizes the risk of penetration into the room carbon monoxide.

The design of the stove makes it possible to use it in the house without fear of damaging the thoughtful interior - the body of the stationary unit can be almost completely hidden in an attractive "shell", which will serve as a heat accumulator.

To understand how a good efficiency is achieved when operating on low-quality fuel, it is necessary to understand the principles of operation of a jet stove.

During thermal decomposition, solid fossil fuels release gaseous substances, which also decompose and eventually turn into wood gas (a mixture of combustible and inert gases), which burns with high heat output.

In an ordinary solid fuel stove, the heat efficiency of wood gas is practically not used, since the gaseous intermediate phase goes with smoke into the pipe, where it cools down and settles on the walls in the form of carbon deposits, which are heavy hydrocarbon compounds. The higher the humidity solid fuel, the less wood gas is formed and the more soot on the walls of the chimney. Accordingly, the worse the stove heats up.

A rocket-type furnace differs from conventional solid-fuel units in that its design makes it possible to provide conditions under which a significant part of the intermediate gases does not escape, but turns into wood and is burned. This is achieved through a horizontal thermally insulated channel, where gases move more slowly than in a vertical pipe, and a thermal insulator prevents cooling and turning into carbon deposits. As a result, even from crude fuel, much more thermal energy is extracted compared to combustion in a conventional furnace.

In complex models of jet heating units, the principle of operation of a long-burning furnace, where afterburning of pyrolysis gases is provided, is combined with design features classic brick ovens, in which heated air and gas circulate through internal channels. At the same time, such a rocket does not need to organize additional blowing - the chimney creates thrust in it, and the higher it is, the more intense the upward flow.

Despite the fact that rocket furnaces are able to squeeze the maximum thermal energy out of low-quality fuel, optimal performance They demonstrate efficiency when using dry firewood.

Difficulties and disadvantages

The disadvantages include:

• manual control of the furnace - fuel has to be added regularly (the burn-out time of the bookmark depends on the heater configuration);
• some structural elements heat up to high temperatures and threaten to burn in case of accidental contact with the skin;
• it is not rational to use a rocket as sauna stove because it warms up the room for a long time.

The design of the jet stove looks extremely simple, but it took a lot of time to invent such a unit, since the pledge effective work is an accurate calculation so that the combustion mode of the fuel is optimally correlated with the thrust force, etc.

Important! Rocket furnaces are a heat engineering system that requires fine balancing. Failure to comply with the dimensions of the structure or errors in assembly, improper operation of the unit turn into the fact that the stove roars loudly during operation due to an unstable gas vortex in the chimney, requires more fuel with low heat transfer and quickly overgrows with soot.

The jet stove was invented in the USA, and the details of its construction are not disclosed - only corrected drawings are publicly available, based on which it is difficult to build a truly efficient heater.

Stove stove at home

Models for outdoor and camping use

Suitable for heating water and cooking jet furnaces the simplest modification, made of metal pipes or bricks. They are easily made with their own hands for household needs.

For the manufacture of a metal cooking outdoor stove, two pipes connected by a knee at a right angle are sufficient. Legs from reinforcing bars and a stand for dishes are welded to the structure (so that there is a gap between the bottom of the tank and the pipe cut for smoke to escape).

street rocket stove from pipes

This design is improved by inserting another elbow with a pipe into the horizontal pipe, the height of which should be less than the chimney part - it will serve as a vertical firebox.

An even more functional modification is a camp stove made of a rectangular pipe with a firebox welded at an angle (it also serves as an ash pan). It is quite simple to make such a rocket oven with your own hands according to the drawings.

Robinson Camping Rocket Oven with Dish Racks

It takes 5 minutes, 20 whole bricks and two more halves to make the simplest brick street jet stove. Plus a metal dish rack.

Drawing of a Robinson oven with a stand for dishes

Such a stove must first be brought to operating mode - to warm up the pipe, burning paper and wood chips, since gas stagnates in a cold pipe, preventing the fuel from flaring up well. When the pipe warms up, a powerful draft will appear when the firewood is ignited.

Reactive Brick Stove

Attention! A jet stove with a horizontal firebox has a significant drawback - it is necessary to constantly push the burning firewood. An inclined or vertical hopper, along the walls of which the firewood slides down under its own weight, makes the unit more convenient to use.

Heating and cooking ovens for rooms

For heating a greenhouse, garage or workshop, you can also use jet units, which are easily and quickly assembled by hand.

An analogue of a primitive furnace made of a metal pipe is being built from bricks on earthen floor or specially prepared foundation. A brick rocket stove is assembled from solid ceramic or fireclay bricks using a heat-resistant mortar.

Stationary brick oven on an earthen floor

A more efficient version of a heating rocket stove is made using a metal barrel that serves as a casing and allows you to insulate the riser (an inner pipe that acts as a combustion chamber and chimney). As a heater, ash, sifted sand, a mixture of sand with fireclay clay are used. Thermal insulation helps to create conditions for the efficient production of wood gas, and the more it is released from the fuel, the higher the heat output of the wood stove. In addition, this thermal insulation material(it needs to be well compacted when laying) plays the role of a heat accumulator, capable of heating the air in the room for several hours after the firewood has burned out.

Furnace Rocket of 21 bricks

Advanced Heaters

A jet stove with a free gas outlet is not suitable for use as a heating one, so it is supplemented with smoke exhaust channels and a heat exchanger. Drawings of a rocket furnace of various designs help to visually see the difference.

The principle of operation of the improved unit is as follows:

• so that in the vertical channel it is supported heat, which contributes to the production of wood gas, it is thermally insulated with a fire-resistant material, while a casing is installed on top (from a barrel or pipe larger diameter) with hermetically closed top;
• the combustion chamber is equipped with a door, in the lower part a special channel is provided for supplying secondary air - this blower is required for afterburning wood gas (in simple models air enters only through the firebox without a door);
• due to the installation of a chimney pipe in the lower part of the casing, the heated air does not go directly into the atmosphere, but circulates through the channels inside the furnace body, actively releasing heat;
• flue gases with the highest temperature enter the upper part of the body, directly under the flat cover, which makes it possible to use it as a hob, and the already cooled stream rushes into the chimney;
• The efficiency of the stove is increased by sucking in secondary air for burning pyrolysis gases, and the intensity of its supply is regulated by the system itself, since it depends on how quickly the flue gases cool in the upper part of the body.

Advanced reactive heating units include a long-burning rocket stove, which can be made from a gas cylinder, as well as a water-jacketed stove.

Jet heating unit from a propane cylinder

A gas cylinder rocket stove is an easy-to-make wood-burning stove that consumes fuel economically and heats the room efficiently.

It is used to assemble:

• empty propane tank (unit body);
• pipe steel diameter 100 mm (for the arrangement of the chimney and vertical channel);
• profile steel pipe 150x150 mm (firebox and hopper are made);
• sheet steel 3 mm thick.

Making a furnace from a gas cylinder requires the use of a welding machine. If you plan to assemble such a rocket oven with your own hands, the drawings will help you accurately observe the optimal dimensions of all structural elements.

Scheme of the processes in the rocket furnace

At the preliminary stage of work, a gas cylinder should be prepared - turn off the valve, fill the container to the top with water to ensure that gas vapors that can explode from a spark are removed from the container. Then the upper part is cut along the seam. In the lower part of the resulting cylinder, a hole is cut under the chimney, and in the bottom - under the combustion chamber with an attached firebox. The vertical channel is brought out through a hole in the bottom, a structure from a profile pipe is welded from the bottom side, according to the rocket drawing.

Attention! Lid from sheet metal it should be made removable and a non-combustible sealant (asbestos cord) should be provided for reliable sealing. The flat lid is used as a cooking surface.

If you are installing a rocket furnace from a gas cylinder on your own, you should carefully consider the quality of the welds and check their tightness - air should not flow uncontrollably into the operating furnace. If everything is in order, you can install a chimney.

Important! The top of the chimney must be raised to a height of 4 meters relative to the level of the firebox in order to provide the necessary draft intensity.

Such a furnace for the home is regulated in terms of power by the volume of fuel loading. The jet stove is put into operation by supplying air through the combustion chamber, this is regulated by the bunker cover. Further, secondary air is constantly supplied to the unit. This stove for heating explodes at the end of the combustion process, since it is impossible to shut off the supply of secondary air, and soot settles on the inner walls of the vertical channel. The cover of the casing is made removable so that it can be periodically removed.

Boiler unit

A long-burning boiler can be obtained by mounting a water circuit on the chimney of a stove made from a gas cylinder or other materials, but according to the same scheme indicated above. However, the heating of water in the circuit of such a unit will be inefficient, since the main part of the thermal energy is transferred to the air of the room and to the containers on the hob.

An effective version of a rocket furnace from a metal barrel

If you want to create a rocket boiler for water heating with high efficiency, you will have to sacrifice the cooking function. Do-it-yourself rocket stove according to the drawing below can be mounted in a short time.

This will require:

• fireclay bricks and refractory masonry composition (for mounting the base of the stove with a firebox);
• steel pipe with a diameter of 70 mm (for a vertical channel);
• steel barrel (for casing);
• refractory heat insulator;
• sheet steel 3 mm thick and a metal barrel (or pipe) of a smaller diameter than the casing (for arranging a water jacket and smoke channels for heating the water circuit);
• steel pipe with a diameter of 100 mm for the chimney;
• container, pipes and connecting pipes for arranging a heat accumulator.

A rocket furnace with a water circuit is characterized by the fact that the thermal insulation of the vertical channel provides an optimal mode for burning pyrolysis gases, while all the heated air enters the "coil" with a water jacket and gives off the main part of the thermal energy there, heating the coolant.

Rocket stove with water circuit

The heat accumulator will continue to supply the heated coolant to the heating circuit even after the furnace itself has cooled down. The water tank is provided with a thick layer of insulation.

Heating unit with bed

A rocket stove with a bench is a device that can create a comfortable environment in one room. Such a unit cannot be used to heat several rooms, not to mention the whole house.

The arrangement of such a long-burning unit with your own hands requires accurate calculations - its power depends on the size of the stove body and its maximum allowable length a boar on which a couch is arranged. It is also important to choose the right cross-section of pipes for mounting the structure. Errors will result in the fact that the jet furnace will quickly become tightly overgrown with soot or will roar loudly during operation due to the turbulence of gas flows.

The design of the oven with a stove bench

Dimensions and proportions of the structure

To build a do-it-yourself rocket stove, detailed drawings must be prepared, indicating the dimensions of all elements. At the stage of project preparation, calculations are made based on the base values ​​to which all the others are tied.

The basic calculated values ​​are:

• D is the diameter of the drum (furnace body);
• S is the area of ​​the inner cross section of the drum.

Calculations of the design parameters are carried out taking into account that:

1. The drum height (H) is between 1.5 and 2 D.
2. The drum is coated with 2/3 N (if it is planned to cut it curly, then 2/3 of the height should be the average).
3. The thickness of the coating layer on the drum is 1/3 D.
4. The area of ​​the inner cross section of the vertical channel (riser) is 4.5-6.5% of S, optimal value– in the range of 5-6%.
5. The height of the vertical channel is as high as the design of the furnace allows, but the gap between the top edge of the riser and the drum cover must be at least 70 mm for normal flue gas circulation.
6. The length of the flame pipe (fire pipe) must be equal to the height of the vertical channel.
7. The cross-sectional area of ​​the igniter is equal to the corresponding indicator of the riser. Moreover, it is recommended to use a profiled square-section pipe for the fire pipeline, in this case the furnace works more stable.
8. The cross-sectional area of ​​the blower is ½ of the cross-sectional area of ​​the furnace and riser. For stability and smooth adjustment of the furnace mode, a rectangular profile pipe with an aspect ratio of 2: 1 is used, which is laid flat.
9. The volume of the secondary ash pan depends on the volume of the drum minus the volume of the riser. For a barrel stove - 5%, for a gas cylinder stove - 10%. For intermediate volume tanks, it is calculated according to linear interpolation.
10. The cross-sectional area of ​​the external chimney is 1.5-2 S.
11. The adobe pad under the external chimney should be 50-70 mm thick - if the channel is made of round pipe, counting from the bottom point. The thickness of the pillow under the chimney is halved if the bench is mounted on wooden floors.
12. The thickness of the coating layer of the bench above the chimney channel is 0.25 D if the drum from the barrel is 600 mm, and 0.5 D if the drum from the cylinder is 300 mm. If the coating layer is reduced, the structure will cool down faster after heating.
13. Flue Height outer pipe should be 4 meters.
14. The length of the gas duct, on which the length of the bed depends: for a stove from a barrel - up to 6 m, for a stove from a cylinder - up to 4 m.

A long-burning rocket furnace made from a 600 mm diameter barrel reaches a power of about 25 kW, and a heating rocket made from a 300 mm cylinder reaches up to 15 kW. It is possible to regulate the power only due to the volume of fuel loading; such a stove does not have air regulation, since an additional flow violates the furnace mode and provokes the release of gases into the room. By changing the position of the blower door, it is not the power that is regulated, but the operating mode of the furnace.

Lining Features

The quality of the thermal insulation of the riser directly affects the efficiency of the heating unit. Light fireclay bricks SHL and river sand mixed with alumina are available for lining in our area. An external metal casing should be provided for the lining, otherwise the materials will quickly absorb carbon deposits and the furnace will roar during operation. The end face of the lining is tightly covered with furnace clay.

Proper lining

When using hewn fireclay bricks, the remaining cavities are filled with sand. If only sand is used for lining, it is sifted from large debris and covered in layers - each approximately 1/7 of the pipe height. Each layer is compacted tightly and sprinkled with water to form a crust. The backfill must be dried for a week, and then cover the end with a layer of oven clay. Then the construction of a rocket furnace with their own hands continues according to the drawings.

Heating unit options

Arrangement of a rocket furnace from a gas cylinder can also be performed in the case of creating a heater with a bench. The design is somewhat different from the one discussed above.

The changes concern:

• flame tube length;
• the presence of thermal insulation of the vertical channel;
• connecting a horizontal rather than a vertical external chimney.

Scheme of the rocket furnace

Note! The extended part of the external chimney is an ash pan, into which there must be access for cleaning - a metal door sealed with non-combustible material.

Due to the fact that the chimney channel can be made long and curved, it is easy to give the stove an original shape.

Option for making a stove bench with an original shape

The adobe coating, which acts as a heat accumulator, is made from a mixture of oily clay with sand and chopped straw.

Principles of starting the stove

Important! Continuous combustion reactive furnaces are launched exclusively “on a warm pipe”.

Before loading regular fuel, kindling is carried out with paper, shavings, straw and other dry light materials, which are placed in an open blower. When the vertical channel warms up enough, the hum of the stove subsides or changes tone. This is a signal that you can lay the main fuel, it will flare up from the booster.

The jet furnace will not adjust itself, so the hopper cover of a small furnace or the blower door of a stationary unit should be kept open until the standard fuel flares up and the furnace hums. The door is closed, reducing the sound to a "whisper". When the sound of the oven intensifies again, the door is closed again a little tighter. If the door is slammed, then lifting it up you can let the fuel ignite normally.

Rocket stove mobile - convenient hiking option, undemanding to fuel and economical. Stationary units, depending on the design and size, are used for heating residential and auxiliary premises.

A rocket stove made of long-burning bricks, despite the simplicity of design, can solve a number of problems for owners of cottages and private houses. These include not only the functions of heating and cooking, but also the creation of an original interior and comfort in the room.

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Principle of operation

During the thermal decomposition of solid organic fuel, gaseous substances are released, which also decompose and turn into wood gas during combustion, which has a high level of heat transfer during combustion.

In conventional solid fuel stoves, wood gas goes into the pipe along with the gas, where it cools and settles on the walls in the form of soot. In a rocket-type furnace, due to the horizontal channel, the gases move more slowly, do not have time to cool down, but burn out, giving off a large amount of heat.

In models of reactive heating devices complex design heated air and gas passes through a series of internal channels. Then they move to the upper part of the body, under the hob, where it burns out completely. For such a rocket, there is no need for additional blowing. The draft in them is created due to the chimney, and the longer its length, the more intense the upward flow.

Principle of operation

In this diagram, the principle of operation of a rocket stove with a stove bench

Advantages and disadvantages

Rocket long-burning furnaces have the following advantages:

• high coefficient useful action- not less than 85%;
• high speed of heating the room - 50 m² will become warm in less than 1 hour;
• the absence of soot - the exhaust during the combustion of fuel does not form soot, but is formed in the form of steam and carbon;
• the possibility of functioning on solid fuel any kind;
• low consumption - fuel consumption by a rocket stove is 4-5 times less than a conventional stove under equal conditions: combustion time interval and heating temperature;
• the possibility of arranging a warm bed;
• the duration of heat retention in a well-heated structure without adding fuel - up to 12 hours.

There are many advantages to such a furnace, but there are also bad sides.

The disadvantages include:

• manual method of controlling the heating device - fuel burns out quickly, and it is required to report it regularly;
• the high heating temperature of some structural elements threatens to burn the owners in case of accidental contact;
• the heating rate does not allow the use of a rocket oven for baths;
• the aesthetic component of such a device is not for everyone and is not suitable for any interior;
• the danger of carbon monoxide penetration into living rooms.

materials

Do-it-yourself building materials for the construction of a long-burning rocket furnace are selected depending on the calorific value of the fuel. For laying the main part of the body, a simple red oven brick is usually used. The firebox and the furnace bunker are lined with fireclay bricks.

If it is planned to use high-calorie fuel (for example, coal), then refractory bricks are used for the construction of almost all parts of the structure. The masonry elements are fastened with an aqueous solution of a mixture of sand and clay.

Regardless of the type of design for a long-burning rocket furnace, you will need to buy furnace fittings:

• blew;
• grates;
• furnace doors;
• intermediate cap;
• chimney pipe.

Tools

To build a rocket-type furnace with your own hands, you need to prepare in advance a set of tools for work, which should consist of:

• trowels for scooping up and distributing the solution. It is more convenient to work with a tool with a handle slightly shifted to the side;
• picks or hammers - picks for hewing individual parts of bricks;
• grinders with a diamond blade for sawing solid blocks into quarters and halves;
• mallets with a rubber tip for leveling bricks in masonry;
• twisted cord - moorings;
• building level;
• square and tape measure;
• shovels.

You also need to stock up on two containers for preparing a solution, concrete and a metal mesh for sifting ingredients.

How to do it yourself?

Before you make a rocket furnace, you need to decide on the place of its installation, with the dimensions of the future design, and develop a diagram. The technology of masonry itself is quite simple, any novice builder can master it.

The simplest design of a rocket furnace can be built from 20 bricks per suburban area and use it to heat food brought from home.

Location selection

Before starting construction, the first step is to choose a place. brick ovens missile type is recommended to be placed closer to front door. In this case, the ash after cleaning will not need to be carried through the entire room, which will positively affect the overall dust content of the room.

It is also desirable that there are no rafters located closer than 40 cm to the chimney at the exit point of the pipe. And yet, the stove should not be adjacent to the outer wall of the house so that expensive heat does not go to heat the street.

Solution preparation

Cement mortar under the influence of high temperatures quickly cracks, therefore, only a mortar consisting of clay and sand is used for laying brick heating devices.

Their proportions are determined experimentally, depending on the quality of the clay. Most often in a ratio of 1:2 or 1:3, and the higher the fat content of the clay, the less it is added to the solution.

First, the clay must be soaked, filtered, and then sand is introduced. The resulting solution should have the consistency of thick sour cream. You can check the level of its viscosity in the following way:

• place a wooden stick or trowel handle into the mixture;
• remove the tool and shake well;
• check the thickness of the adhering layer: if less than 2 mm add clay, more than 3 mm - sand.

The preparation of the mortar must be approached with all responsibility, since only a plastic mixture of the required density can fill all the irregularities of the bricks and ensure their strong adhesion.

Masonry rocket stove of 20 bricks

Ordering a rocket furnace for 20 bricks

An example of a brick rocket stove

Masonry rocket stove with stove bench

A brick rocket stove, even equipped with a bench, is small. The order shown in the figures (below) allows you to assemble the structure without the use of metal products. Only the doors will be iron. Subsequently, the body can be coated with clay to give it more rounded shapes.

row number	Number of bricks, pcs.	Description of masonry	Drawing
1	62	Formation of the furnace base	(click to enlarge)
2	44	The formation of the base of the channels for heating the couch along the entire structure. Fastening mortgages for mounting a cast-iron door
3	44	Repeating the contour of the second row
4	59	Complete channel coverage. The beginning of the formation of a vertical smoke channel and a furnace
5	60	The construction of the couch	(click to enlarge)
6	17	Continuation of laying the smoke channel
7	18
8	14
9; 10	14	Smoke channel formation	(click to enlarge)
11	13
12	11	The beginning of laying the chimney pipe. From here begins the channel through which the air from the hob will go down to move to the stove bench
13	10	The end of the formation of the surface under the hob. Laying asbestos gasket, which is covered with sheet steel.	(click to enlarge)
14; 15	5	Closing the chimney channel and forming a low wall between the bench and the hob.

After completing the masonry work, the home-made rocket stove must be dried, carefully, by heating at low intensity. First, no more than 20% of the firewood norm is laid in the firebox, and the device is heated twice a day for 30-40 minutes.

According to this scheme, the stove is heated until its outer surface is cleared of damp spots. Drying, depending on the dimensions of the device, may take from three to eight days. During this time, the room should be well ventilated, especially in summer.

Accelerating drying can lead to cracking of the masonry, that is, the device will become unsuitable for further heating.

Ready view

You need to start a brick rocket stove only with a warm chimney. For a small device, this property is not so significant, and a larger stove for a cold pipe only uses firewood in vain.

Therefore, before loading the fuel rate after a long break in operation, the rocket stove must be heated with paper, dry shavings, straw, etc., placing them in a blower with the door open. When the hum in the stove lowers its tone or subsides, then you can load all the fuel into the furnace, it should ignite by itself from the already existing fire.

A rocket stove with a bed is not a fully self-regulating device for external conditions and fuel energy efficiency. Therefore, at the beginning of the furnace, the standard amount of fuel blower door left in the open position. After the stove starts to hum strongly, it is covered to a position where the sound emitted is barely audible.

Only dry wood can be used to heat the stove, wet wood will not allow the stove to warm up to the desired temperature, which can lead to reverse draft.

Conclusion

The brick jet stove is becoming an increasingly popular heating appliance for small buildings both temporary and permanent residence. This is explained by the simplicity of execution, the cheapness of the material, the duration of autonomous operation and the high heat transfer of this design.

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A do-it-yourself rocket stove, drawings of which most home craftsmen would probably like to have in their archive, can be made, in principle, even within one day, since its design is quite simple. If you have skills in working with tools, reading drawings, stocked necessary materials, then making a simple stove of this type will not be difficult. It should be noted that it can be made from a variety of materials that are at hand, but much will depend on where the oven is planned to be installed. The rocket stove has a slightly different principle of operation from other heating devices, and can be either stationary or portable.

Stationary rocket stoves are installed inside the house along the walls or on the area reserved for cooking in the courtyard of the house. If the stove is installed indoors, then it is able to heat a room up to 50 square meters. m.

Portable versions of the rocket stove are usually very small and can easily fit in the trunk of a car. Therefore, when traveling, for example, to a picnic or to a dacha, such a stove will help to boil water and cook dinner. Moreover, the fuel consumption in the rocket stove is quite small, even dry branches, splinter or grass tufts can be used as it.

The principle of operation of the rocket-type stove

Despite the simplicity of the rocket stove, its design uses two principles of operation that the developers borrowed from other types of solid fuel stoves. So, for its effective work, the following principles are taken:

• The principle of free circulation of gases released from the fuel through the created furnace channels, without the forced creation of a chimney draft.
• The principle of post-combustion of pyrolysis gases released during the combustion of fuel in the mode of insufficient oxygen supply.

In the simplest designs of rocket ovens, which are used only for cooking, only the first principle of operation can operate, since it is rather difficult to create the necessary conditions for pyrolysis and the organization of gas afterburning in them.

To understand the constructions and understand how they work, you need to consider some of them in turn.

The simplest design of a rocket stove

To begin with, it is worth considering the simplest device of a direct combustion rocket furnace. As a rule, such appliances are used only for heating water or for cooking, and exclusively for outdoors. As can be seen from the figure below, these are two pipe sections connected by a right angle bend.

The furnace for such a design of the furnace is the horizontal part of the pipe, and fuel is laid into it. Often, the firebox has a vertical load - in this case, three elements are used to make a simple stove - these are two pipes of different heights, installed vertically and connected from below by a common horizontal channel. The lower pipe will serve as a firebox. For the manufacture of a stationary version of the simplest design scheme, a brick is often used, installed on a heat-resistant mortar.

To achieve higher efficiency, the furnace was improved, and additional elements appeared, for example, the pipe began to be installed in a housing that enhances the heating of the structure.

1 - outer metal body of the furnace.

2 - pipe - combustion chamber.

3 - a channel formed by a jumper under the fuel chamber and designed for free passage of air into the combustion area.

4 - the space between the pipe (riser) and the body, densely filled with a heat-insulating composition, for example, ash.

The heating of the furnace is as follows. A light combustible material, such as paper, is first placed in the firebox, and when it flares up, wood chips or other main fuel are thrown into the fire. As a result of the process of intense combustion, hot gases are formed that rise along the vertical channel of the pipe and go outside. On the open section of the pipe and install a container for boiling water or cooking.

An important condition for the intensity of fuel combustion is the creation of a gap between the pipe and the installed container. If its hole is completely blocked, then the combustion inside the structure will stop, since there will be no draft, which provides air supply to the combustion area and raises the heated gases up. To avoid problems with this, a removable or stationary stand for the container is installed on the upper edge of the pipe.

This diagram shows a simple design, on the loading opening of which a door is installed. And to create thrust, a special channel is provided, which forms the lower wall of the combustion chamber and a plate welded at a distance of 7-10 mm from it. Even when the firebox door is completely closed, the air supply will not stop. In this scheme, the second principle is already starting to work - without active oxygen access to burning wood, the pyrolysis process can begin, and the continuous supply of "secondary" air will contribute to the afterburning of the released gases. But for a fully-fledged process, one more important condition is still missing - high-quality thermal insulation of the secondary afterburner chamber, since certain temperature conditions are necessary for the combustion process of gases.

1 - air channel in the combustion chamber, through which blowing is carried out with the furnace door closed;

2- zone of the most active heat exchange;

3 - ascending flow of hot gases.

Video: a variant of the simplest rakten furnace from an old cylinder

Improved Rocket Furnace Design

The design, intended both for cooking and for heating the room, is equipped not only with a furnace door and a second body, which serves as a good external heat exchanger, but also with an upper hob. Such a rocket stove can already be installed inside the premises of the house, and the chimney from it is brought out into the street. After carrying out such a modernization of the furnace, its efficiency increases significantly, since the device acquires a lot of useful properties:

• Due to the second outer casing and insulating heat-resistant materials that thermally insulate the main furnace pipe (riser), hermetic closure of the upper part of the structure, the heated air retains a high temperature for much longer.

• In the lower part of the body, a channel for supplying secondary air began to be mounted, successfully carrying out the necessary blowing, for which an open firebox was used in the simplest design.
• The smoke pipe in a closed design is not located at the top, as in a simple rocket furnace, but at the lower rear of the case. Due to this, the heated air does not go directly into the chimney, but gets the opportunity to circulate through the internal channels of the appliance, heating, first of all, the hob, and then diverging inside the body, providing its heating. In turn, the outer casing gives off heat to the surrounding air.

This diagram clearly shows the whole process of the furnace operation: in the fuel hopper (pos. 1) there is a preliminary combustion of fuel (pos. 2) in the mode of insufficient air supply "A" - this is regulated by a damper (pos. 3). The resulting hot pyrolysis gases enter the end of the horizontal fire channel (pos. 5), where they are afterburned. This process takes place due to good thermal insulation and the continuous supply of "secondary" air "B" through a specially provided channel (pos.4).

Further, hot air rushes into the inner pipe of the structure, called the riser (pos. 7), rises through it under the "ceiling" of the body, which is the hob (pos. 10), providing its high-temperature heating. Then the gas flow passes through the space between the riser and the outer shell-drum (pos. 6), providing heating of the shell for further heat exchange with the air in the room. Then the gases go down and only after that they go into the chimney (pos. 11).

To achieve maximum heat transfer from the fuel and provide the necessary conditions for the complete combustion of pyrolysis gases, it is important to maintain the highest and most stable temperature in the riser channel (pos. 7) To do this, the riser pipe is enclosed in another pipe of a larger diameter - a shell (pos. 8 ), and the space between them is tightly clogged with heat-resistant mineral composition(pos. 9), which will serve as thermal insulation (a kind of lining). For these purposes, for example, a mixture of kiln masonry clay with fireclay sand (in a ratio of 1: 1) can be used. Some craftsmen prefer to simply fill this space very tightly with sifted sand.

Increasing the efficiency of heat extraction in rocket stoves

To increase the efficiency of the rocket stove, other designs with more efficient heat extraction were developed, both for using the device in outdoor conditions and for indoor use - for space heating or water heating.

stove-stove

For cooking or preparing food for the winter, stoves are made that are arranged according to the principle described above, but have an expanded hob that allows you to install several containers at once.

In this model of a rocket stove, a vertical pipe with a top-loading firebox built into it with a door is located under the hob. Therefore, hot air heats it directly, and in order for the entire panel to be hot, the heated gases, gathering under the panel, are directed to a horizontal channel passing under its entire surface and connected to a vertical section of the chimney.

Additionally, the design is equipped with legs, which gives it stability and reliability. It should be noted that when such a stove is not used for its intended purpose, it can be used as a regular garden table.

In addition to this outdoor model, several types of structures have been developed for indoor use, allowing you to effectively heat rooms or heat water.

Rocket oven with water circuit

The rocket furnace with a water circuit consists of the following elements:

• The furnace is installed on a solid concrete base, in order to avoid distortions and deformation of structures.
• The lower part of the structure, which includes the furnace compartment (pos. 2) and the fire channel, is laid out from fireclay bricks (pos. 1). The furnace has a vertical loading. At the bottom there is an ash pan (pos. 3) with a side door for regular cleaning of the furnace from accumulated ash.

• The vertical channel (riser) (pos. 4) is made of a steel pipe, which is put on a thick layer of thermal insulation (pos. 5) and an outer metal case.
• A heat exchanger assembly with a water jacket in the walls (pos. 6) and horizontal plates creating a kind of labyrinth (pos. 7) is hermetically fixed on top of the outer casing to ensure maximum heat exchange area and time.

Attempts are being made to install a water register in this place. However, as practice shows, this approach is impractical - the temperatures here due to the afterburning of pyrolysis gases are very high, and the pipe register has every chance of quickly burning out.

• Hot air, passing through the heat exchanger, bending around the metal plates, heats the entire massive block, and the metal gives off heat to the water circulating through the water jacket.
• Further, the cooled gas flow goes into the chimney (pos. 8).
• Water circulation occurs through a heat accumulator (pos. 9), which may well be made from an old boiler or other closed container with valves for connecting a cold and a fence hot water. The option of connecting a heating radiator is not excluded, although, in truth, such a furnace is unlikely to justify itself in such a role.
• Hot water from the heat storage tank can be directed through a pipe connected to it (pos. 10) to the points of water intake for domestic needs.

Such a rocket stove is perfect for installation in a country house or in a private house, where it is possible to connect such a heat storage tank to an autonomous water supply system. The stove will help to significantly reduce the cost of heating water and heating, as this model does not require a large number solid fuel or connecting it to some additional energy sources.

Rocket stove with bench

Another way to effectively use a rocket stove is to equip a fairly massive structure with a heated bench. It should be noted that such a bed can take the form of a bed or a sofa, successfully replacing these pieces of furniture, since by laying a mattress on its surface, you can comfortably settle down for a day or night rest. The bed can be made of brickwork or stones and clay mass.

The design of this version of the rocket furnace consists of the following components and elements:

• A lid-closed furnace with vertical fuel loading with a secondary air intake chamber located in its lower part.
• The furnace passes into a horizontally located fire channel, at the end of which pyrolysis gas is burned.
• The hot gas flow rises along the vertical channel (riser) to the hermetically sealed "ceiling" of the housing, where it gives off part of the thermal energy to the horizontal stove - the hob. Then, under the pressure of the hotter gases following it, it diverges into the heat exchange channels, giving off heat to the surfaces of the drum, and goes down.
• In the lower part of the furnace there is an entrance to the horizontal pipe channels that run under the entire surface of the bed. Moreover, one, two or more turns can be laid in this space. corrugated pipe, in the form of a coil, through which hot air circulates, heating the stove bench. This heat exchange pipeline is connected at the end to a chimney pipe led out through the wall of the house.

• It should be noted that in the case of making a bed made of brick, the channels can also be laid out of this material, without the use of metal corrugated tubes.
• The heated stove and stove bench, giving off heat to the room, will themselves serve as a kind of “battery” capable of heating an area up to 50 m².

The metal drum of the furnace can be made of a barrel, a gas cylinder or other durable containers, and also made of bricks. Usually the material is chosen by the craftsmen themselves as far as financial possibilities and convenience of work.

A rocket stove with a brick bed looks neater and is somewhat easier to install than a clay version, but the material costs will be about the same.

Video: one more original solution increasing the heating efficiency of the rocket furnace

We fold a rocket stove with a stove bench out of brick

What is needed for work?

The brick heating structure proposed for execution is designed on the principle of a rocket stove. Construction size at standard parameters brick (250 × 120 × 65 mm) will be 2540 × 1030 × 1620 mm.

It should be noted that the structure is, as it were, divided into three parts:

• The furnace itself - its size is 505 × 1620 × 580 mm;
• Furnace compartment - 390 × 250 × 400 mm;
• Bed 1905 × 755 × 620 mm + 120 mm headrest.

For laying the oven you will need the following materials:

• Red brick - 435 pcs.;
• Blower door 140 × 140 mm - 1 pc.;
• Cleaning door 140x140 mm - 1 pc.;
• The furnace door is desirable (250 × 120 mm - 1 pc.), Otherwise there is a risk of smoke in the room.
• Cooking stove 505 × 580 mm - 1 pc.;
• Rear metal panel-shelf 370 × 365 mm - 1 pc.;
• Asbestos sheet 2.5 × 3 mm thick to create a gasket between metal elements and bricks.
• Chimney pipe, 150 mm in diameter, with a 90 ? outlet.
• clay and sand for mortar or a ready-made heat-resistant mixture. It should be noted here that for 100 bricks laid flat, with a joint width of 5 mm, 20 liters of mortar will be required.

The design of this top-loading rocket furnace is quite simple, trouble-free and efficient in operation, but only if its laying is done with high quality, in full accordance with the order.

In the absence of experience in the work of a bricklayer and stove-setter, but a great desire to independently install such a heating device, it is worth making sure, and for starters, lay down the structure “dry”, without mortar. This process will help you figure out the location of the brick in each of the rows.

In addition, in order for the seams to be of the same width, it is recommended to prepare sizing wooden or plastic slats for masonry, which will be laid on the previous row before laying the next one. After setting the solution, it will be easy to remove them.

Under the laying of such a furnace, it is necessary to have a flat and solid foundation. Despite the fact that the design is quite compact, and its weight is not as large as, for example, that of a Russian stove, a floor made of thin boards is not suitable for its installation. In the event that the floor, although wooden, is very durable, before starting laying under the future furnace, it is necessary to lay and fix heat-resistant material, for example, asbestos 5 mm thick.

Ordering a brick rocket stove with a stove bench:

Illustration	Brief description of the operation to be performed
	The first row is laid out solid, and the brick must lie in strict accordance with the pattern shown in the diagram - this will give strength to the entire base. For masonry, 62 red bricks are required. The diagram clearly shows the connection of all three sections of the furnace. The corners on the side bricks of the facade of the firebox are cut off or rounded - so the design will look neat.
	Second row. At this stage of the work, internal chimney channels are laid, through which the gases heated in the furnace will pass, giving off heat to the stove bench bricks. The channels are connected to the combustion chamber, which also begins to form in this row. The first brick of the wall separating the two channels under the stove bench is cut obliquely - this “nook” will collect unburned combustion products, and the cleaning door installed opposite the bevel will allow it to be easily cleaned. For laying a row, 44 bricks are required.
	On the second row, the doors of the blower and cleaning chambers are mounted, which are necessary for periodically putting the ash chamber and internal horizontal channels in order. The doors are fixed with wire, which is twisted on the ears of the cast-iron elements, and then laid in the seams of the masonry.
	Third row. It almost completely repeats the configuration of the second row, but, of course, taking into account the laying in the dressing, and therefore it will also require 44 bricks.
	Fourth row. At this stage, the channels passing inside the couch are blocked with a continuous layer of bricks. A furnace opening is left, and a channel is formed that will heat the hob and discharge combustion products into the chimney. In addition, a rotary horizontal channel is blocked from above, which discharges heated air under the stove bench. For laying a row, you need to prepare 59 bricks.
	Fifth row. The next step is to cover the couch with a second cross layer of bricks. The chimney ducts and the furnace also continue to be removed. For a row, 60 bricks are being prepared.
	Sixth row. The first row of the headrest of the couch is laid out, and the part of the stove begins to rise, on which the hob will be installed. It still has chimneys. For a row you need 17 bricks.
	Seventh row. The laying of the headrest is being completed, for which bricks cut obliquely are used. The second row of the base under the hob rises. For masonry, 18 bricks are required.
	Eighth row. The construction of the furnace with three channels is being laid. It will take 14 bricks.
	The ninth and tenth rows are similar to the previous, eighth, laid out in the same way, alternately, in dressing. 14 bricks are used for each row.
	11th row. Continuation of masonry according to the scheme. This row will take 13 bricks.
	12th row. At this stage, a hole is formed for installing the chimney pipe. The hole brought under the stove is supplied with a brick cut obliquely for a smoother flow of heated air into the adjacent channel leading to the lower horizontal channels located in the bench. 11 bricks were used per row.
	13th row. A base is formed for the slab, and the central and side channels are combined. It is through it that hot air will flow under the stove, and then flow into a vertical channel leading under the stove bench. 10 bricks are laid.
	13th row. On the same row, the basis for laying the hob is being prepared. To do this, along the perimeter of the space in which two vertical channels were combined, heat-resistant material - asbestos - is laid.
	13th row. Then, a solid metal plate is laid on the asbestos gasket. In this case, it is not recommended to install a hob with opening burners, since when they are opened, smoke can enter the room.
	14th row. The arranged hole for the chimney pipe is blocked and the wall separating hob from the bed area. Only 5 bricks are used for a row.
	15th row. This row that raises the wall will also require 5 bricks.
	15th row. On the same line, in continuation rear wall, a metal shelf is fixed next to the hob, which can be used as a cutting board. It is attached to brackets.
	15th row. The picture-scheme is well modeled how the hob can be used. In this case, the pan is placed exactly on that part of the stove that will warm up first of all, since a hot air stream will pass under it.
	After completion of all the work described in the order, a chimney pipe is built into the hole, from the back of the furnace, which leads out into the street.
	From the back, the design also looks quite neat, so it can be installed both near the wall and in the middle of the room. Such a stove is perfect for heating in a country house. If the stove and chimney are decorated finishing materials, then the building can become an original addition, and very functional, for any private house. As you can see, the corner formed under the cutting shelf is very convenient for drying and storing firewood.
	To fully consider the design, you need to see its projection from the end side.
	And the last figure shows well what should happen as a result of the work done, if you look at the stove from the side of the bench.

In conclusion, I would like to emphasize that the design of a rocket stove can be called one of the simplest and most affordable for self-production, compared with other heating devices. Therefore, if such a goal is set - to acquire a stove in the house, but experience in such work is clearly not enough, then it is best to choose this particular option, since when building it, it is difficult to make a mistake in the configuration of its internal channels.

Let's say right away: a rocket stove is a simple and convenient wood-fueled heating and cooking device with good, but not exceptional parameters. Its popularity is explained not only by the catchy name, but more so by the fact that it can be made with your own hands and not by a stove-maker or even a bricklayer; if necessary - literally in 15-20 minutes.

And also by the fact that, with a little more work, you can get an excellent stove bench in the house without resorting to the construction of a complex, expensive and cumbersome Russian or bell-type stove. Moreover, the very principle of the device of the furnace-rocket gives great freedom to design and the manifestation of creative abilities.

Rocket stove - wood-fired device

But perhaps more remarkable is the "jet furnace" by the huge number of associated, at times completely absurd inventions. Here, for example, are a few pearls snatched at random:

• "The operating principle of the furnace is the same as that of the MIG-25 ramjet engine." Yes, the MIG-25 and its descendant MIG-31 did not sit down near the ramjet engine (ramjet), as they say, and did not sit down in the bushes. On the 25th and 31st there are bypass turbojet engines (turbojet engines), four of which then pulled the Tu-144 and still pull other cars. And any furnace with any jet engine (RD) is technical antipodes, see below.
• "Reverse jet furnace". Is this a tail-first stove, or what?
• “But how will she blow such a pipe?” A naturally aspirated stove does not blow into the chimney. On the contrary, the chimney pulls out of it, on natural draft. The higher the pipe, the better it pulls.
• “The rocket stove is a combination of a Dutch bell-type stove (sic!) with a Russian stove bench.” Firstly, there is a contradiction in the definition: a Dutch oven is a channel oven, and any bell-type oven is anything but a Dutch one. Secondly, the couch of the Russian stove warms up in a completely different way than the rocket stove.

Note: in fact, the rocket stove was nicknamed so because in the wrong firing mode (more on that later), it emits a loud whistling rumble. A properly tuned rocket stove whispers or rustles.

These and similar inconsistencies, of course, are confusing and prevent us from making a rocket furnace properly. So let's figure out what is true about the rocket stove, and how to use this truth correctly so that this really good stove shows all its advantages.

Furnace or rocket?

For complete clarity, we still need to figure out why a stove cannot be a rocket, and a rocket cannot be a stove. Any RD is the same internal combustion engine, only the outflowing gases themselves act as pistons, connecting rods with a crank and transmission. In a piston internal combustion engine, already at the moment of combustion, the high temperature of the working fluid creates a large pressure that pushes the piston, and it already moves the entire mechanics. The movement of the piston is active, the working fluid pushes it to where it tends to expand itself.

When fuel is burned in the RD combustion chamber, the thermal potential energy of the working fluid is immediately converted into kinetic energy, like that of a load falling from a height: since the exit to the nozzle is open to hot gases, they rush there. In RD, pressure plays a subordinate role and nowhere exceeds a few tens of atmospheres, this, for any conceivable nozzle cross section, is not enough to disperse a flashlight to 2.5M or put a satellite into orbit. According to the law of conservation of momentum (momentum), an aircraft with a RD at the same time receives a push in reverse side(recoil momentum), this is jet thrust, i.e. thrust from recoil, reactions. In a turbofan engine, the second circuit creates an invisible air shell around the jet. As a result, the recoil momentum is, as it were, contracted in the direction of the thrust vector, so the turbofan is much more economical than a simple turbofan.

There is no conversion of types of energy into each other in the furnace, therefore it is not an engine. The stove simply distributes the potential thermal energy properly in space and time. From the point of view of the furnace, the ideal RD has an efficiency of 0%, because it just runs on fuel. From the point of view of a jet engine, the furnace has an efficiency = 0%, it only dissipates heat and does not pull at all. On the contrary, if the pressure in the chimney rises to or above atmospheric (and without this, where will the jet thrust or active force come from?), The stove will at least smoke, or even poison the residents or start a fire. Draft in the chimney without pressurization, i.e. without the expenditure of energy from the side, it is provided due to the temperature difference along its height. Potential energy here, again, is not converted into any other.

Note: in a rocket propellant rocket engine, fuel and oxidizer are fed into the combustion chamber from tanks, or they are immediately filled into it if the rocket engine is on solid fuel. In a turbojet engine (TED), the oxidizing agent - atmospheric air - is injected into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes a certain fraction of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the power of the jet, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), air is supplied to the combustion chamber by hypersonic velocity pressure. A lot of experiments were carried out in the ramjet, but there were no production aircraft with it, there is not and is not expected, the ramjet is painfully capricious and unreliable.

Can or not can?

Among the myths about the rocket stove, there are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the "racquet" with the Chinese kan.

As a child, the author had a chance to visit the Amur region, in the region of Blagoveshchensk, in winter. There were a lot of Chinese there in the villages even then, who were scrambled in all directions from the cultural revolution of the Great Chairman Mao and his completely frostbitten hungweibins.

Winter in those parts is not Moscow, frost at -40 is a common thing. And what struck and aroused interest in stoves in general was how Chinese fanzes were heated by kans. In Russian villages, firewood is transported by carts, smoke is a pillar from the chimneys. And all the same, in the log hut, not in a children's girth, by morning the corners were frosted over from the inside. And the fanza is built like country house(see fig.), the windows are covered with fish bladder or even rice paper, bunches of chips or twigs are placed in the kan, but the room is always warm.

However, there are no subtle heat engineering tricks in the canal. This is the usual, only small, kitchen stove with a lower exit to the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is arranged. Chimney, for the sake of fire safety - outside the building.

The effectiveness of the kan is determined primarily by the thermal curtain it creates: the couch goes around, if not the entire perimeter from the inside, except for the door, then 3 walls for sure. What once again confirms: the design and parameters of the furnace must be linked to those of the heated room.

Note: The Korean ondol oven operates on the principle of a warm floor - a very low stove bench occupies almost the entire area of ​​​​the room.

Secondly, in the very cold, the Kans were drowned with argal - dried droppings of ruminants, domestic and wild. Its calorific value is quite high, but argal burns slowly. In fact, an argal fire is already a long-burning stove.

It is not in the Russian custom to stick twigs into the oven every now and then, and our peasants abhorred cooking on animal feces. But travelers of the past highly valued argal as a fuel, collected it along the way and carried a supply with them, diligently protecting it from getting wet. N. M. Przhevalsky, in one of his letters, argued that without the argal, he could not have carried out his expeditions in Central Asia without loss. And for the British, who were disdainful of the argal, 1/3-1/4 of the personnel of the detachments returned to the base. True, he was recruited from sepoys, Indian soldiers in the English service, and pandits - spies recruited from the local population. One way or another, but the highlight of the rocket stove is not at all in the couch on the hog. To get to it, you will have to learn to think in an American way: all the primary sources on the rocket furnace are from there, and utter speculation is generated only and only by misunderstanding.

How to deal with rockets?

From our point of view, the original technical documentation of rocket furnaces should be studied with caution, but not at all because of inches-millimeters, liters-gallons and the subtleties of American technical jargon. Although they also mean a lot.

Note: A textbook example is "Naked conductor runs under the carriage". Literary translation - a naked conductor runs under the car. And in the original article from Petroleum Engineer, it meant "Bare wire runs under the crane trolley."

The rocket stove was invented by members of survival societies - people with a peculiar way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they always automatically converted everything into money, taking into account their own benefit; a person with a different worldview in America simply does not get along. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of a spiritual outburst, but out of the calculation of dividends. Not in this life, but in that one.

Note: How much the average inhabitant of the greatest empire in history is afraid of everything can only be understood by talking with them long enough. And sociopsychologists go out of their way there, convincing that living, languishing in fear, is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Without heating and cooking, of course, you will not survive. What is an oven for? For the time being, for the time being, the survivors were content with camping stoves. But then, according to the Americans themselves, in 1985-86. they were greatly impressed by two films that were released with a short interval and triumphantly went around all the screens of the world: the Soviet science fiction parody of the entire human race "Kin-dza-dza" and Hollywood's "The Day After", about the global nuclear war.

The survivors realized that after the nuclear winter there would be no extreme romance, but there would be the planet Plyuk in the Kin-dza-dza galaxy. It will be necessary to be content with the newly appeared plukans "ka-tse" in small quantities, bad, expensive and difficult to access. Yes, all of a sudden someone hasn’t watched “Kin-dza-dza” - like a match in Plukansky, a measure of wealth, prestige and power. It was necessary to invent your own furnace, none of the existing ones is designed for a post-nuclear spit.

Americans are very often endowed with a sharp mind, but a deep one is found as the rarest exception. A completely normal and with an IQ above the average, a US citizen may sincerely not understand how it doesn’t reach another that he himself has already “caught up” and how someone else may not like what suits him.

If an American has already understood the essence of an idea, then he brings the product to its possible perfection - what if there is a buyer, you can’t sell raw iron. But the technical documentation, which looks beautiful and neat, can be drawn up in fact extremely carelessly, or even deliberately distorted. And what is it, this is my know-how. Maybe I'll sell it to someone. Whether there will be a plus, or not, but for now the know-how is worth the money. In America, such an attitude to business is considered quite honest and worthy, but there a clinical alcoholic at work will never miss a stopper and will not drag a couple of bolts home to the farm. On that, in general, the whole of America stands.

And the Russian breadth of the soul is also a double-edged sword. Most often, our master simply understands from a sketch how this thing works, but in the details it turns out to be careless and overly trusting in the source code: how is it for a crafty brother to deceive his own. If you don't have something, then you don't need it. It seems clear how everything is spinning there - already my hands itch. And there, perhaps, until it comes to a hammer, chisel and related literature, still count and count. Moreover, important points can be omitted, veiled or deliberately wrong.

Note: an American acquaintance once asked the author of this article - how did we, the really stupid ones, elect the very smart Reagan as president? And you, really smart, tolerate a slobbering senile with dyed eyebrows in the Kremlin? True, then in America no one in a bad dream would have imagined that in the next century a black citizen with a Muslim name would settle in the Oval Office, and his first lady would dig a garden near the White House and grow turnips there. Times is changing, as Bob Dylan once sang for a completely different reason ...

Sources of misunderstanding

There is such a thing in technology - the square-cube law. Simply put, when something changes in size, its surface area changes squarely, and its volume changes cubed. Most often, this means that changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. With regard to solid fuel stoves, the square-cube law is doubly valid, because fuel is also subject to it: it releases heat from the surface, and its reserve is contained in the volume.

Note: a consequence of the square-cube law - any specific design of the furnace has a certain allowable fork of its size and power, within which the specified parameters are provided.

Why, for example, is it impossible to make a potbelly stove the size of a refrigerator and with a power of about 50-60 kilowatts that way? Because the potbelly stove, in order for it to somehow warm, must itself be heated inside to at least 400-450 degrees. And in order to warm up the volume of the refrigerator to such a temperature at a given heat transfer, firewood or coal needs as much as it does not fit in it. There will also be no sense from a mini-potbelly stove: the heat will leave through the outer surface of the furnace, which has grown relative to its volume, and the fuel will not give it away more than it can.

The square-cube law acts triple on the rocket furnace, because she is "licked" in an American professional way. With our kondachka, it is better to stay away from her. Here, for example, here in Fig. American development, which, judging by its demand, many of our craftsmen take as a prototype.

The original blueprint for the mobile rocket stove

With the fact that the exact grade of refractory clay (fire clay) is not indicated here, ours will sort it out. But, to be honest, who noticed that, judging by the absence of an external chimney and the presence of transportation holes (carrying pipe), this stove is mobile with an open firebox? And most importantly, that a 20-gallon keg with a diameter of 17 inches (431 mm with change) went to her drum?

Judging by the designs from Runet, no one at all. They take this thing and adjust it according to the principle of geometric similarity to a domestic 200-liter barrel with a diameter of 590 mm on the outside. Many guess to arrange a blower, but the bunker is left open. Are the exact proportions of vermiculite with perlite for lining the riser and forming the furnace body (core) not indicated? We make the lining homogeneous, although it will be clear from what follows that it should consist of insulating and accumulating parts. As a result, the furnace roars, the fuel eats only dry, and a lot, and even before the end of the season, it overgrows with burning inside.

How was the rocket oven born?

So, already without science fiction with futurology, the survivors needed a stove to heat the house, operating with high efficiency on low-quality random wood fuel: wet wood chips, twigs, bark. Which, moreover, will need to be reloaded without stopping the furnace. And most likely it will not be possible to dry in a firewood shed. Heat dissipation after heating needs at least 6 hours to get enough sleep; getting pissed off in a dream on Pluka is no better than in America. Additional conditions: the design of the furnace should not contain complex metal products, non-metallic materials and components that are required for the manufacture of production equipment, and the furnace itself must be available for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics and other energy dependencies.

They immediately took a couch from the kan, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning furnaces work even on sawdust, but only dry, and do not allow shutdown with additional loading. Nevertheless, they were taken as a basis, they were very attracted by the high efficiency achieved simple ways. But in an attempt to make the "long stoves" work on bad fuel, another circumstance became clear.

What is wood gas?

The high efficiency of long-burning furnaces is achieved largely due to the afterburning of pyrolysis gases. Pyrolysis is the thermal decomposition of solid fuel into volatile combustible substances. As it turned out (and the survivors have their own research centers with highly qualified specialists), the pyrolysis of wood fuel, especially wet fuel, continues for a long time in the gas phase, i.e. The pyrolysis gases that have just been released from the wood still require quite a lot of heat to form a mixture that can burn out completely. This mixture was called wood gas, woodgas.

Note: in Runet, woodgas has created more confusion, because in American vernacular, gas can mean any fuel, cf. e.g. gas station - gas station, gas station. When translating primary sources without knowing the American technical, it turned out that woodgas is just wood fuel.

Before that, no one saw wood gas: in conventional furnaces, it is formed immediately in the furnace, due to the excess energy of fiery combustion. The designers of long-burning stoves came to the conclusion that the primary air must be heated, and the exhaust gases must be retained in a significant volume over a large mass of fuel, simply by trial and error, so they overlooked the wood gas.

It turned out not so when firing with bundles of twigs: here the primary pyrolysis gases were immediately dragged into the chimney. Wood gas could have formed in it at some distance from the furnace, but the primary mixture had cooled by that time, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney like soot. Which quickly tightened the channel completely; amateurs building rocket furnaces at random are well familiar with this phenomenon. But the survivors eventually figured out what was going on and made the right oven anyway.

Who are you, the Rocket Stove?

There is an unspoken rule in technology: if it seems that it is impossible to create a device according to the given requirements, then read, smart guy, school textbooks. That is, go to the basics. In this case, to the basics of thermodynamics. Survivors do not suffer from sick pride, they turned to the basics. And found main principle operation of his furnace, which has no analogues in others: slow adiabatic afterburning of pyrolysis gases in a weak flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume, subject to the square-cube law, and the energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but practically into free volume. And now - learn to think in an American way.

How does a rocket oven work?

The scheme of the final fruit of the labors of the survivors is presented on the left side of fig. Fuel is loaded vertically into the bunker (Fuel Magazine) and burns, gradually settling down. Air enters the combustion zone through the blower (Air Intake). The blower must provide an excess of air so that it is enough for afterburning. But not excessive cold air did not cool the primary mixture. With vertical loading of fuel and a blind cover of the bunker, the flame itself acts as a regulator, however, not very effective: when it flares up too much, it pushes the air out.

The device of rocket furnaces

Further things already non-trivial begin. We need to warm up, and with good efficiency, a large stove. The law of the square-cube does not allow: the meager heat will immediately dissipate so much that the pyrolysis will not reach the end, and the thermal gradient from the inside to the outside will not be enough to transfer heat into the room; everything will whistle through the trumpet. This law is harmful, you can't break it in the forehead. Okay, let's see in the basics, if there is anything there that is not subject to him.

But how, there is. That same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares are resting, and the cubes can be reduced even to a thimble, even to a skyscraper.

Imagine a completely isolated volume of gas. Let's say it releases energy. Then the temperature and pressure will begin to rise until the energy release stops, and will freeze at a new level. Great, we burned the fuel completely, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do it without technical difficulties? And most importantly - how, without violating the adiabat, to supply air for afterburning?

And we will make the adiabatic process non-equilibrium. How? Let the primary gases immediately from the combustion source go into a pipe covered with high-quality insulation with a low intrinsic heat capacity (Insulation). Let's call this pipe for ourselves a flame or a burning tunnel (Burn Tunnel), but we will not sign it (know-how! You can’t catch up - give money for consulting drawings! Without theory, of course. Who sells the fixed capital at retail.) On the diagram, so that not accused of "opacity", denoted by the flame.

Along the length of the flame tube, the adiabatic index changes (this is a non-equilibrium process): the temperature will first drop slightly (wood gas is formed), then it will increase sharply, the gas will burn out. It is possible to release it into the accumulator, but we forgot - what will pull gases through the flame tube? Supercharging means energy dependence, and there will be no exact adiabat, but something mixed with an isobar, i.e. the efficiency drops.

Then we will lengthen the pipe by half, keeping the insulation so that the heat does not go in vain. We bend the “idle” half up, making the insulation weaker on it; how to keep the heat seeping through it, we will think a little later. In a vertical pipe, a temperature difference will appear along the height, which means thrust. And good: the thrust force depends on the temperature difference, and with an average in the flame tube of about 1000 degrees, it is not difficult to achieve a difference of 100 at a height of about 1 m. So, while we have made a small economical potbelly stove, now we need to think about how to use it warmly.

Yes, it does not interfere with additional encryption. If we call the vertical part of the flame tube the primary or internal chimney (Primary or Internal Vent), then they will guess the main idea, we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipes with upward current - the riser (riser). Purely American: correct and incomprehensible.

Now let's recall the heat transfer after heating. Those. we need a cheap, always available and very capacious heat storage. There is nothing to invent here, the adobe (Thermal Mass) was invented by the primitives. But it is not fire resistant, it does not hold more than 250 degrees, and we have about 900 at the mouth of the riser.

It is not difficult to convert high-potential heat into medium-potential heat without loss: you need to give the gas the opportunity to expand in an isolated volume. But, if the expansion is left adiabatic, then the volume will need to be too large. And that means - material and labor intensive.

I had to bow to the basics again: immediately after leaving the riser, let the gases expand at constant pressure, isobarically. This requires heat to be removed to the outside, about 5-10% of the heat output, but it will not disappear and will even be useful for quickly warming up the room during the morning fire. And further along the course of gases - isochoric cooling (in a constant volume); Thus, almost all the heat will go into the battery.

How to do it technically? We cover the riser with a thin-walled iron drum (Steel Drum), which will also stop heat loss from the riser. The “drum” turns out to be a bit high (the riser sticks out a lot), but it doesn’t matter: we will cover it with the same adobe for 2/3 of the height. We attach a stove bench with an airtight chimney (Airtight Duct), an external chimney (Exhaust Vent), and the stove is almost ready.

Note: the riser and the drum that covers it look like a furnace hood over an elongated hail. But the thermodynamics here, as we see, is quite different. It is useless to try to improve the bell-type stove by building on a high loft - only the extra material and work will go away, and the stove will not get any better.

It remains to solve the problem of cleaning the channel in the couch. For this, the Chinese have to break the kan from time to time and remake it, but we are not in the 1st century. BC. we live when kan was invented. We will arrange a secondary ash pan (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of flue gases in it, everything in them that did not burn out immediately condenses and settles. The cleanliness of the external chimney is guaranteed by this for years.

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to fool around with the latches. We will simply make a cover from a metal sheet on screws with a mineral cardboard gasket.

small rocket

The next task of the designers was to create on the same principle a small continuous combustion oven for cooking in the warm season. IN heating season the drum cover (Optional Cooking Surface) of a large oven is suitable for cooking, it heats up to about 400 degrees. The small rocket stove was supposed to be portable, but it was permissible to make it with an open firebox, because. when warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law, forcing it to work for themselves: they combined the fuel tank with the blower, see Fig. at the beginning of the section on the right. It is impossible to do this in a large furnace, fine adjustment of the furnace mode as the fuel settles (see below) will be impossible.

Here, the volume of incoming primary air (Primary Air) turns out to be small relative to the heat release area, and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the cover of the hopper (Cover Lid). The 45-degree hopper optimizes the oven's auto-adjustment for standard cooking routines, but it's harder to make.

Secondary air for afterburning wood gas in a small oven enters through additional holes in the mouth of the riser or simply flows under the burner if there is a cooking vessel on it. If a small furnace is close to the limit size (about 450 mm in diameter), then an optional secondary woodgas frame may be needed for complete afterburning.

Note: It is not possible to supply secondary air to the mouth of the riser of a large furnace through the holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas-smoke path is lower than atmospheric pressure, as it should be in the furnace, flue gases will be emitted into the room due to strong turbulence. Here their kinetic energy, harmful to the furnace, affects; this, perhaps, is the only thing that makes a rocket stove related to a jet engine.

The small rocket stove has revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (a Bond stove in the West) will help to cook a stew or wait out a snowstorm in a one-two-man tent, but it will not save a group caught on a spring campaign by a belated bad weather. A small rocket furnace is only a little larger, it can be quickly made from nowhere, but is capable of developing power up to 7-8 kW. However, we will talk about furnace-rockets from anything we will talk further.

Also, the small rocket oven has spawned many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for the device of a compact and rather powerful water heater, see the video below. The large rocket furnace was also modified, we will talk about this a little at the end, but for now let's dwell on more significant things.

Video: a water heater based on a rocket stove designed by Gabriel Apostol

How to fire a rocket?

A rocket furnace with long-burning furnaces has a common property: they need to be launched only on a warm pipe. For a small one, this is not essential, but a large one on a cold chimney will only burn fuel in vain. Therefore, a large rocket furnace, before loading regular fuel into the bunker after a long break in the furnace and kindling, must be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open blower. The end of acceleration is judged by a change in the tone of the hum of the furnace or its subsidence. Then you can load fuel into the bunker, and its ignition will occur by itself from the accelerating fuel.

The rocket furnace, unfortunately, does not apply to furnaces that are completely self-adjusting to the quality of the fuel and external conditions. At the beginning of regular fuel combustion, the blower door or the bunker cover in the small furnace is fully opened. When the stove hums strongly, cover it "to a whisper." Further, in the process of burning, it is necessary to gradually cover the access of air, guided by the sound of the stove. Suddenly, the air damper slammed shut for 3-5 minutes - it's okay, if you open it, the stove will flare up again.

Why such difficulties? In the process of burning the fuel, the flow of air into the combustion zone increases. When there's too much air, the furnace roars, but don't get excited: the excess air now cools the primary gas mixture, and the sound is amplified as the steady swirl in the riser clumps into a clump. Pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and carbon deposits from the soot cemented by bituminous particles are deposited in the riser. This, firstly, is a fire hazard, but most likely it will not come to a fire, the riser channel will quickly overgrow with soot completely. And how to clean it if you have a non-removable drum cover?

In a large furnace, a spontaneous change of regime occurs abruptly, when the top of the sticks drops to the bottom edge of the bunker, and in a small furnace, gradually, as the fuel mass settles. Since an experienced housewife does not leave her for a long time when cooking on the stove, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

With a large oven, this trick will not work: a high riser pulls very strongly, and the air gap is needed so thin (and it also needs to be regulated) that it is impossible to achieve a stable furnace mode. It’s easier with a separate blower: the mass of fuel, rounded in section, is easier for air to flow around from the sides, a too-flamed flame pushes it there. The stove turns out to some extent self-regulating; however, within very small limits, so you still have to manipulate the blower door from time to time.

Note: for the sake of simplicity, it is impossible to make a bunker of a large furnace without a tight lid, as is often done. Due to the unregulated additional air flow through the fuel mass, it is unlikely that it will be possible to achieve a stable operation of the furnace.

Materials, dimensions and proportions, lining

Now let's see what a home-made rocket stove should be from the materials available to us. Here, too, we need to look back: not everything that is at hand in America is also with us, and vice versa.

Of what?

For a large stove with a bed, more or less reliable experimental data is available for products with a drum from a 55-gallon drum with a diameter of 24 inches. 55 gallons is 208-plus liters, and 24 inches is almost exactly 607mm, so our 200-litre is fine without additional conversion. Keeping the parameters of the furnace, the diameter of the drum can be halved, up to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

Pipes of different sizes will go to the blower, bunker, firebox and riser, see below, round or shaped. So it will be possible to make an insulating lining of the furnace part from a mixture of equal parts of furnace clay and fireclay crushed stone, without resorting to brickwork; we will talk about the riser lining in more detail below. Combustion in the rocket furnace is weak, therefore the thermochemistry of gases is gentle and the thickness of the steel of all metal parts, except for the gas pipeline in the stove bench, is from 2 mm; the latter can be made from thin-walled metal corrugated, here the flue gases have already completely exhausted both in terms of chemistry and temperature.

For external coating, the best heat accumulator is adobe. Subject to the dimensions indicated below, the heat transfer of a rocket furnace in adobe after combustion can reach 12 hours or more. Other parts (doors, covers) are made of galvanized metal, aluminum, etc., with sealing gaskets made of mineral cardboard. Conventional oven fittings are not suitable enough, it is difficult to ensure their tightness, and a slotted rocket oven will not work properly.

Note: it is desirable to equip the rocket stove with a view in the external chimney. Although the gas view in the high riser seals the common smoke path tightly, strong winds outside can prematurely draw heat out of the couch.

Dimensions and proportions

The basic calculated values ​​to which the rest are tied are the drum diameter D and its cross-sectional area along the inside S. Everything else, based on the size of the available iron, is determined as follows:

1. Drum height H - 1.5-2D.
2. Drum coating height - 2/3H; for the sake of design, the edge of the coating of the design can be made oblique curvilinear, then 2/3H must be maintained on average.
3. The thickness of the coating of the drum is 1/3D.
4. The cross-sectional area of ​​the riser is 4.5-6.5% of S; it is better to stay within 5-6% of S.
5. The height of the riser - the larger the better, but the gap between its edge and the drum tire must be at least 70 mm; its minimum value is determined by the viscosity of the flue gases.
6. The length of the flame tube is equal to the height of the riser.
7. The cross-sectional area of ​​the flame tube (fire pipe) is equal to that of the riser. It is better to make a fire pipe from a square corrugated pipe, so the furnace mode will be more stable.
8. The cross-sectional area of ​​the blower is 0.5 from its own firebox and riser. A more stable furnace mode and its smooth adjustment will be provided by a rectangular corrugated pipe with sides 2: 1, laid flat.
9. The volume of the secondary ash pan is from 5% of the original volume of the drum (excluding the volume of the riser) for a furnace from a barrel to 10% of it for a furnace from a cylinder. Interpolation for intermediate drum sizes is linear.
10. The cross-sectional area of ​​​​the external chimney is 1.5-2S.
11. The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is considered from its lower point. If the bench is on wooden floors, the pillow under the chimney can be halved.
12. The height of the bed coating above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. It can be less, but then the heat transfer after heating will be shorter.
13. The height of the external chimney is from 4 m.
14. Permissible length of the flue in the bed - see next. sec.

The maximum thermal power of a barrel rocket furnace is approximately 25 kW, and a gas cylinder furnace is about 15 kW. Power adjustment - only by the size of the fuel load. By supplying air, the oven is put into operation, and nothing more!

Note: In the original survivalist ovens, the riser cross-section was taken as 10-15% S, based on very wet fuel. Then, in the same place, in America, rocket stoves with a stove bench for a bungalow appeared, designed for air-dry fuel and more economical. In them, the riser section is reduced to the recommended ones and here 5-6% S.

Riser lining

The efficiency of the rocket furnace largely depends on the thermal insulation of the riser. But American lining materials, alas, are not available to us. In terms of stocks of high-quality refractories, the United States has no equal, where they are considered strategic raw materials and are sold with caution even to proven allies.

From our available materials in terms of heat engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-digged river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous, in the oven they are quickly saturated with soot. Then the stove will roar with any air supply, with all the consequences. Therefore, we need to surround the riser lining with a metal shell, and be sure to cover the end of the lining with furnace clay.

Lining schemes for 3 types of furnaces are shown in fig. The bottom line here is that with a decrease in the size of the drum, the proportion of its direct heat transfer through the bottom and the unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining capacity can be reduced. This makes it possible to correspondingly increase the relative cross section of the annular descent of the flue gases in the drum.

Riser lining schemes in rocket furnaces

For what? Firstly, the requirements for an external chimney are reduced, since the outer traction pulls better now. And since it pulls better, then the permissible length of the hog in the stove bench falls more slowly than the dimensions of the furnace. As a result, if a stove from a barrel warms up a bench with a pine forest up to 6 m long, then half the size from a cylinder is 4 m.

How to line with sand?

If the riser lining is fireclay, then the remaining cavities are simply covered with building sand. River self-digging for lining entirely of sand does not need to be carefully prepared, it is enough to select large debris. But they pour it in layers, in 5-7 layers. Each layer is compacted and sprayed until a crust forms. Then the whole backfill is dried for a week, the upper edge is covered with clay, as already mentioned, and the construction of the furnace is continued.

balloon rocket

From the foregoing, it is clear that it is more profitable to make a rocket stove from a gas cylinder: less work, fewer unsightly parts in sight, and the stove heats up almost the same. Thermal curtain or underfloor heating in Siberian frost will heat a room of 50 square meters with a power of 10-12 kW. m or more, so here, too, a balloon rocket turns out to be more profitable, it is rarely necessary to launch a large barrel at full power with maximum efficiency.

Craftsmen, apparently, also understood this; at least some. For example, here in Fig. - drawings of a balloon furnace-rocket. On the right is the original; the author, it seems, was wisely versed in the initial developments and, in general, everything turned out right for him. On the left - the necessary improvements, taking into account the use of air-dry fuel and warming up the couch.

Drawings of a rocket stove from a gas cylinder

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the flame tube can be made shorter. The cross-sectional area of ​​its air duct is about 10% of the riser cross-section. The furnace always works with the secondary fully open. First, the mode is set with a primary valve; finely adjust the hopper cover. At the end of the furnace, the furnace will roar, but here it is not so scary; the author of the design provides for a removable drum cover to clean the riser. She, of course, should be with a seal.

Rockets from anything

Canned

Scheme of a rocket furnace from cans

Tourists, hunters, and fishermen (many of them members of survival societies) soon converted the small rocket stove into a camping stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by applying a horizontal fuel supply, see the diagram on the right. True, at the cost of some inconvenience: the sticks need to be pushed inward as they burn out. But the furnace mode began to hold iron. How? Due to the automatic redistribution of air flows through the blower and over / through the fuel. The power of a jar rocket furnace is in the range of 0.5-5 kW, depending on the size of the furnace, and is regulated by approximately three times the amount of fuel loading. The basic proportions are also simple:

• The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
• The height of the combustion chamber is 3-5 of its diameters.
• The cross section of the blower is 0.5 from its own combustion chamber.
• The thickness of the thermal insulation layer is not less than the diameter of the combustion chamber.

These proportions are very approximate: changing them by half does not prevent the stove from working, and the efficiency in the campaign is not so important. If the insulation is made of wetted sandy loam, as described above, the joints of the parts can simply be smeared with clay (left pos. in the figure below). Then the stove, after 1-2 fires, will acquire strength, allowing it to be transported without any special precautions. But in general, any of the improvised non-combustible materials will do the insulation, next. two pos. A burner of any design must provide a free flow of air, 3rd pos. A rocket stove welded from a steel sheet (right pos.) with sand insulation is twice as light and more economical than a potbelly stove of the same power.

Compact Rocket Furnaces

brick

Brick rocket stove

We will not expand on large stationary rocket furnaces: in them all the initial thermodynamics goes to pieces, and they are deprived of one of the main advantages of the original furnace - ease of construction. We will talk a little about rocket stoves made of bricks, clay or stone fragments, which can be made in 5-20 minutes when there are no tins at hand.

Here, for example (see the video below), is a completely thermodynamically complete rocket furnace of 16 bricks laid dry. The voice acting is English, but everything is clear without words. A similar one can be folded from fragments of bricks (see Fig.), Cobblestones, fashioned from clay. For 1 time, a stove made of greasy earth is enough. The profitability of all of them is not so hot, the height of the combustion chamber is small, but it’s enough for pilaf or urgently to warm up.

Video: 16 brick rocket oven (eng)

new material

Scheme of the Shirokov-Khramtsov furnace

Of domestic developments, the Shirokov-Khramtsov rocket furnace deserves attention (see the figure on the right). The authors, not caring about survival in a plus, applied modern material- heat-resistant concrete, adjusting all thermodynamics to it. The components of refractory concrete are not cheap; a concrete mixer is needed for mixing. But its thermal conductivity is much lower than that of most other refractories. The new rocket furnace became more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. It turned out a rocket stove - a fireplace.

Do rockets fly in the bath?

Isn't a rocket stove suitable for a bath? It seems to be possible to arrange a heater on the drum cover. Or flowing instead of a couch.

Unfortunately, the rocket oven is not suitable for a bath. To get light steam, the sauna stove must immediately warm up the walls with thermal (IR) radiation, and immediately, or a little later, the air, by convection. To do this, the oven must be a compact IR source and a convection center. The convection from the rocket furnace is distributed, and it gives little IR at all, the very principle of its design eliminates significant radiation losses.

In conclusion: rocket stove-makers

In successful designs of rocket furnaces, there is still more intuition than precise calculation. And therefore - good luck to you too! - a rocket oven is a fertile field for craftsmen with a creative streak.published

P.S. And remember, just by changing your consciousness - together we change the world! © econet

Such a simple heating device as a rocket stove is not known to every person. Meanwhile, it has few equals in simplicity and efficiency. It cannot be said that she has the best performance but it also has few shortcomings. There are many varieties of these furnaces, differing in design and purpose. We will look at them in more detail as part of our review.

Device and principle of operation

Rocket furnaces have practically nothing to do with the design of rocket engines or jet turbines. On the contrary, they are extremely simple structurally, in contrast to the above devices. The similarity is noticeable only in a quietly noisy flame and high combustion temperature - all this is observed after the stove enters the operating mode.

Consider the device of rocket furnaces - they consist of the following elements:

• Firebox - a vertical or horizontal area in which firewood burns;
• Combustion chamber (it is also a flame tube, riser) - here the process of fuel combustion occurs with the release of a large amount of heat;
• Blower - necessary for the correct operation of the stove and starting the process of burning pyrolysis gases;
• Thermal insulation - envelops the vertical part, forming a drum together with the body;
• Bed - used for its intended purpose;
• Chimney - removes combustion products into the atmosphere, creating traction;
• The support under ware - provides unhindered exit of heat.

Depending on the type of rocket furnace, certain elements may be missing.

Rocket furnaces with vertical fireboxes (fuel bunkers) and blowers have the greatest efficiency and convenience - large volumes of fuel are placed here, which ensures long-term combustion.

The most important part of the rocket furnace is the vertical drum. It is in it that the highest temperature is observed, since flames break out here. In order for it to start working, it must be thoroughly warmed up. Without this, the combustion process will be weak. To warm up, paper, cardboard, small chips or thin branches are placed in the firebox. As soon as the system warms up, the flame in the drum will begin to burn out with a buzz, which is a sign that the operating mode has been reached.

A rocket (jet) stove without a blower burns wood in a direct way. It is simpler, but less efficient. The blower model supplies secondary air to the base of the riser, which causes intense combustion of combustible pyrolysis gases. This increases the efficiency of the unit.

Fireboxes in rocket furnaces are located horizontally or vertically (at any angle). Horizontal fireboxes are not very convenient, since the firewood in them has to be moved to the combustion zone manually, independently. Vertical combustion chambers are more convenient - we load fuel into them and go about our business. As the logs burn, they will fall down, independently moving towards the combustion zone.

Varieties of rocket furnaces

In this section, we will consider the most common types of rocket stoves used in field and stationary conditions.

Simple metal ovens

The simplest wood-fired jet stove is made from an L-shaped piece of metal pipe. large diameter. The horizontal part is short, it is a firebox. The combustion chamber is located in the vertical part of the pipe, firewood is actively burning here. A small metal plate is often welded into the horizontal section, forming a blower. After warming up, the rocket furnace enters the operating mode, a flame bursts out of its vertical section (flame tube).

Such rocket stoves are used for cooking in camping or outdoor conditions - due to their small area, they are characterized by low heat release, and the vast majority of heat energy escapes through the flame tube. Teapots, frying pans and pots are placed on this pipe so that the raging flame ensures their heating. To maintain traction, stands are located in the upper part of the pipe, on which dishes are placed - combustion products can freely go outside.

In order to make a metal rocket furnace from an L-shaped pipe section more efficient, it is equipped with a metal casing made of old barrel. At the bottom of the barrel you can see a blower, and a flame tube peeps out of the top. If necessary, the internal volume is filled with insulation, for example, ash - it does not burn and retains heat well.

The most convenient are metal rocket furnaces with vertical fireboxes located at an angle to the flame tube. Often, the furnace openings are closed with lids; in this case, air is taken through the blower. Sometimes the firebox is made larger in diameter than the flame tube in order to ensure long-term burning.

Simple brick ovens

A small-sized brick rocket stove is another of the easiest options for building a do-it-yourself rocket stove. For its assembly, cement mortar is not required, it is enough to lay the bricks on top of each other to get at your disposal a convenient brick street cooking unit. In the section on self assembly rocket furnaces, we will suggest that you familiarize yourself with the simplest order for self-assembly.

A do-it-yourself brick rocket stove can be used to heat households. In this case, simple ordering is not enough - you will have to build a stationary version using a special cement mortar. There are many orders for this, you just have to choose the appropriate option. By the way, some variants of such furnaces provide for the presence of a water circuit.

Advantage of brick rocket kilns:

• Simple construction;
• Long-term heat retention;
• The ability to create a comfortable warm couch.

Some models are made combined, they use both steel and bricks.

Complex rocket ovens

A jet stove for heating households or for a bath is characterized by increased complexity. The main link here is still the riser (flame tube), enclosed in a metal case. Its upper part can be used for cooking, forming a kind of cooking surface. The firebox is made large to accommodate an increased amount of solid fuel. The raw materials are metal, bricks and clay.

Streamlined rocket furnaces are made on the basis of clay coating irregular shape, which is well perceived by human vision.

There are projects of wood-burning rocket stoves that provide for the presence of additional modules. Their construction schemes include small boilers for preparing hot water, hobs, water jackets, and even small ovens. Such stoves will help to heat households and create comfortable conditions for a person to live.

A water-jacketed rocket boiler, based on a wood-burning stove, will help warm up a multi-room building. It is equipped with a water circuit for heating the coolant. Additional convenience is created by samples with stove benches - these stove benches are created on the basis of thermal channels between the flame and chimney pipes.

Types of stoves for different operating conditions

A rocket stove with a water circuit, brick or metal, can replace the boiler. The heat exchanger here is arranged in the upper part of the flame tube in the form of a surrounding water jacket. Jumpers are located inside the jacket for more efficient heat removal to the coolant. The design is extremely simple, it can heat households up to several tens of square meters.

A rocket stove for a garage can be made from an old pot-bellied gas bottle or barrel. To do this, two holes are made in the selected container - one in top cover, and the other on the side surface. An L-shaped pipe is inserted inside. With little experience with welding machine, all work will take you a maximum of half an hour.

You can also make an oven of the above-described rocket type from pieces of a square and metal pipe according to the above drawing.

Also, the heating rocket stove "Ognivo-Kozyain" is suitable for heating the garage. This is a shop model made of corrugated aluminum pipe and ordinary sheet iron. It works approximately according to the same scheme and allows you to warm a garage up to 30 square meters. m.

There are no drawings of her in the public domain yet, so you can try to assemble the Flint stove with your own hands based on her photograph. It can also be purchased from the manufacturer's website.

We have already said that a long-burning rocket stove with a water circuit will be required to heat large households. A small household from one room can be heated with a simple stove with a stove bench - this way you save space on furniture. It consists of the following nodes:

• Firebox with vertical loading - logs are placed in it;
• Afterburner - a horizontal section in front of the riser (flame tube), pyrolysis combustion takes place here;
• Riser with a hob - a vertical section with a metal case that gives off heat to the room;
• Horizontal channels - they heat the stove bench, after which the combustion products are sent to the chimney.

A rocket stove for heating a house from one room is coated with clay to make a flat and comfortable bed - here you can lay a mattress or a small blanket.

For hiking use, the most simple ovens missile type, made from metal pipes. They are compact, easy to kindle and extinguish, cool quickly and allow you to quickly cook dinner in the open air. The main thing is not to overdo it with the amount of fuel loaded, so as not to burn the food with a high-temperature flame.

How to increase the efficiency of the stove

Long-burning jet stoves can be made even more efficient with a little tweaking. If the riser (flame tube) is closed with a metal casing, weld vertical pipes of small diameter to the outer surface - they form a convector that effectively heats the air in the premises. This modification method is suitable for metal units used for heating technical premises (for example, garages).

Any metal rocket furnace can be made more efficient by lining it with bricks or natural stone. The masonry will retain heat and slowly release it into the room. At the same time, it will allow you to get rid of unbearable heat with too intense heating.

How to make a DIY rocket stove

Let's start with the simplest brick sample designed for cooking. Such a stove can be quickly folded in your yard without clay mortar, and disassembled after use. It is also possible to assemble a stationary version - for those who like to cook on an open fire. The picture below shows a drawing of the stove, or rather, its ordering. There are only five rows here.

The first row is the base, which includes six bricks. The second row forms the firebox, and the next three rows form the riser chimney. In the first and second rows, halves of bricks are used so that the stove is rectangular, without protruding elements.

Immediately after assembly, you can start kindling - cook any dishes on the fire in cast-iron cauldrons and pans, heat kettles and pots of water.

A sheet metal oven can be both a camping and a stationary option. We have already given her drawing in the previous sections of our review. It can be used for cooking in any conditions.

Large rocket stove with bench

The main advantage of the rocket modification over the Russian stove is its compactness. Even being equipped with a couch, she will please small size. Having made it out of brick, you will have at your disposal an effective source of heat with a comfortable bed - the household will fight for the right to occupy this warm place.

The presented ordering allows you to assemble a brick oven without the use of metal. Only the doors will be made of iron. Subsequently, the bricks can be smeared with clay, which will make the stove more rounded.

The first row forms the base of our rocket oven. It consists of 62 bricks laid according to the pattern shown in the figure. The second row forms channels for heating the couch - they run along its entire length. Cast-iron doors are also mounted here, fixed with metal wire - it is held between the rows. The number of bricks used - 44 pcs. The same amount will be required for the third row, completely repeating the contour of the second. The fourth row completely closes the channels that heat the bed. But here a vertical smoke channel and a firebox are already beginning to form - the row includes 59 bricks.

Another 60 is needed for the fifth row. The bed has already been formed, it remains to finish off the chimney channel and build a hob. The sixth row, which includes 17 bricks, is responsible for this. Another 18 are needed for the seventh row, 14 for the eighth.

The ninth and tenth row will require 14 bricks, the eleventh - 13.

Row number 12 is our key one - the chimney will start from here. Also, a hole begins from here, through which the air that has risen to the hob will go down to the bench - 11 bricks are required (this is the top of the riser). In row No. 13, this process is completed, 10 bricks are spent on it. Now we lay the asbestos gasket, which is covered with a piece of thick sheet steel - this will be the hob.

5 bricks are spent on rows No. 14 and No. 15, they close the chimney channel and form a low wall between the hob and the stove bench.

Similarly, you can assemble a long-burning rocket cauldron by finding the right order. Separate schemes provide for the use of metal nodes.

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