Water supply for industrial enterprises: types of systems and principles of their operation

Urban water supply systems are a complex of engineering structures for the intake, lifting, purification of water, its conservation and delivery to the consumer. It includes the following buildings:

waterworks and pumping stations the first rise, which supply water to the places of its purification;

treatment facilities;

prefabricated clean water tanks;

pumping stations of the second and subsequent rises, supplying water to the city or to industrial enterprises;

conduits and water networks.

In the practice of urban water supply, there are different systems centrally providing consumers with water. The whole variety of water supply systems can be classified according to the following criteria:

By type of natural sources used, - water pipes that take water from surface or underground sources, and water pipes of mixed consumption;

by type of consumer- communal (urban, rural); fire fighting; production, which, in turn, are subdivided by industry (water pipelines of chemical enterprises, thermal power plants, metallurgical plants, etc.);

By territorial coverage of consumers - local (for one object ) and group (or centralized) water pipes that serve a group of objects;

according to the ways of representing water - water pipes with by gravity (gravitational) and with mechanical representation of water (using pumps);

By frequency of use of water - with water circulation, with sequential use on various installations;

by nature of water use- once-through, reverse, sequential (with water reuse);

by types of consumers- household and drinking, industrial, fire-fighting, agricultural;

on the complexity of customer service- combined, incompletely separated, separate systems.

United system provides all three types of consumers, as a rule, with water of drinking quality. Such systems are useful in cases where the industry consumes potable water or a relatively small amount of water. These systems are simpler and have a relatively lower network construction cost, which is usually about 60% of the cost of the entire water supply system.

Incomplete separate system used in the case when the industry consumes a significant amount of water, the quality requirements of which are low. In this case, the construction of an integrated system is unprofitable, because the unjustified costs of purifying water for industrial needs to drinking quality lead to a significant increase in the cost of building and operating a water supply system.

Separate systems provide for the construction of separate systems for drinking, industrial and fire fighting needs. Such systems are very rare.

Urban water supply schemes differ in the set of facilities necessary to provide water of the required quality and quantity. General form the water supply scheme, which includes a complete set of water facilities, is shown in the figure. The source of water supply are natural and artificial reservoirs, rivers, underground artesian and ground water, seas and oceans.

Water supply systems of industrial enterprises are classified according to the methods of using water: direct-flow, reverse and with water reuse.

IN once-through systems water, as a rule, is part of the final product (for example, in the production of mineral acids, liquid suspended complex fertilizers, etc.) or significantly changes its composition (for example, electrolyte water in electrolyzers), and therefore its reuse is inappropriate . In this case, it is discharged after mixing with other wastewater into the local hydrographic network or transferred to a treatment plant.

IN working systems reuse of water supply, when water is used mainly for cooling, it is advisable to cool the heated water (for example, in cooling towers) and serve it for reuse at the same facility. At the same time, only 3-5% of the total amount of water used is supplied from the water source to replenish its losses during circulation. Sometimes recycled water needs not only to be cooled, but also sent for cleaning.

IN reuse systems water discharged by one of the industrial consumers can be used by another (for example, water after trapping fluorine gases in the production of superphosphate is used in the production of ammonium fluoride-hydrofluoride). This makes it possible to reduce the amount of water taken from the water source.

There are 4 water supply schemes:

1 - direct-flow system (water is discharged into reservoirs without treatment). Qp.p. - irretrievable losses of water in production, Qsp. - loss of water to evaporation.

Qp.p. – water losses with industrial products,

Qsp - loss of water for evaporation.

2 - system with clarification of wastewater at treatment facilities.

Qos. – loss of water removed together with the sludge from sewage treatment plants.

3- a water supply system with wastewater treatment before they are discharged into a reservoir

Qline – loss of water removed with sludge treatment facilities.

The most widely used system.

4 - circulating water supply system. The water consumption in it is small, determined by the consumption necessary to replenish the irretrievable water consumption in the process of production and consumption, as well as the periodic replacement of water in the circulation cycles (by blowing). At a TPP with a capacity of 1 million kW, with direct-flow water supply, 1.5 km3 of water is consumed annually, with a circulating system - only 0.12 km3, i.e. 13 times less.

Q entrainment - loss of water with droplet entrainment,

Qdischarge - water loss during system purging,

Qadd - water taken from a water body to replenish water losses in the system.

In this water supply system, the waste water after treatment is not discharged into the reservoir, but is reused in the production system, being regenerated after each production cycle.

5 - system of endorheic water supply (closed system), the most promising, but the most difficult to achieve.

Water use efficiency criteria

Water use efficiency can be assessed by the following three indicators taken together.

The technical excellence of the water supply system is assessed by the amount of recycled water used (%)

The efficiency of using water taken from the source is estimated by the utilization factor

Irrevocable water consumption and losses (%)

,

where Qob, and Qseq. - the amount of water used in circulation and sequentially;

Qist. and Qcheese. - the amount of water taken from the source and entering the water supply system with raw materials;

Q SW - the amount of wastewater discharged into the reservoir.

For the economic assessment of water supply systems, it is necessary to consider the cost of water used, the cost of water supply and their share in the cost of production, the environmental damage caused to the environment due to discharges of polluted effluents, as well as the economic effect of the application of each of the considered schemes.

Rice. The cost of water (C), capital investments (K), environmental damage (U) and economic effect (E) when using 1-4 water supply systems.

The general water supply scheme may vary depending on specific conditions. For example, if the water does not require purification, then the treatment and related facilities fall out of the scheme. When placing the source at higher elevations than the user object, water can be supplied by gravity and there is no need to build pumping stations. Some systems use multiple sources of water supply, resulting in an increase in the number of main facilities.

Water intakes, pumping stations and water treatment facilities.

water intake- this is a hydraulic structure that takes water from a supply source (rivers, lakes, reservoirs) for the needs of water use. In addition, there are water intakes used for the needs of hydropower, irrigation, etc. Water intake facilities must ensure the presence of water in the conduit

in a given quantity

required quality,

in accordance with the water use schedule.

Structures for the intake of water from surface sources are classified according to the type of source (river, reservoir, lake, sea, etc.). Of the river, the most common are coastal, channel, floating, bucket. They can be combined with pumping stations of the first lift.

Coastal water intake structures used on relatively steep river banks are a reinforced concrete well large diameter carried by the front wall into the river. Water enters it through holes equipped with gratings, and then passes through the grids, which provide mechanical water purification.

Run-of-river water intake facilities, which are used on gently sloping banks, have a head extended into the riverbed, water flows by gravity into the coastal well, which is often combined with the pumping station of the first lift.

Floating water intake facilities are a pontoon or barge on which pumps are installed to draw water directly from the river. Water is supplied to the shore through pipes with movable joints laid along a connecting bridge.

In bucket water intake facilities, water first flows from the river into a bucket (artificial dam) located near the shore. The bucket itself is used for settling sediments, as well as for combating ice phenomena - slush, deep ice.

Groundwater intake is a hydraulic structure for the intake of groundwater and its supply to water supply and other water management systems. The choice of a site for groundwater intake equipment is determined by the geological and hydrogeological conditions of the area, the distance from the place of water use, etc. Structurally, such water intakes are divided into wells and mine wells. Wells are the most versatile, technically more advanced type of water intake and are used for centralized water supply. They have high productivity and most fully comply with sanitary requirements. The depth of wells can reach 800m. The flow rate can reach 50 l / s or more. The walls of wells in unstable rocks are reinforced with casing pipes, which enter one into one and, within the boundaries of the aquifer, end with a filter made of porous concrete, gravel, ceramics, and metal meshes. Used to lift water submersible pumps. Often, water wells are equipped with water towers that regulate the pressure and loss of water in the water supply network. The service life of wells is 10-15, sometimes up to 30 years.

Water intake structures are designed to take water from a source and rough clean it mainly from floating objects.

Pumping stationsPumping stations I, II and other lifts serve to lift water. The lifting station 1 usually supplies water to the treatment plant, the lifting station P to the water-regulating reservoir. Their need is determined by the terrain and the length of water transportation. They are equipped with pumps, as a rule, with an electric drive, regulating, warning and instrumentation. Many pumping stations are remotely controlled and fully automated.

Water treatment facilities process natural water in order to give it qualities that meet the requirements of users. If the water in the source satisfies the requirements of the consumer, then there is no need for treatment facilities.

Surface waters are usually not suitable for drinking due to significant turbidity, color and a higher content of bacteria than is acceptable for drinking water. Therefore, before water is supplied to the water supply at treatment facilities, it is clarified (removed suspended and colloidal impurities), color is removed and disinfected (freed from pathogenic bacteria), softened, etc.

Purified water is supplied to the water supply facility through water conduits and is bred on its territory with the help of water supply network.

Water network

The water supply network is a set of water lines (pipelines) for supplying water to places of water use, it is the main element of the water supply system.

The water supply network laid outside the boundaries of buildings is called external. The so-called house branches (pipes) are connected to the water supply network line, through which water is supplied to individual structures.

The houses are equipped internal water supply networks.

Used for plumbing equipment water pipes. The choice of pipes depends on the required pressure in the water supply network, the nature of the soil, the laying method and economic factors. For underground laying, cast-iron, asbestos-cement and steel pipes are most common, reinforced concrete and plastic pipes are also applicable. The depth of pipe laying depends on the level of soil freezing, water temperature and mode of operation (in Ukraine, about 1.5-2 m). The maximum depth of pipe laying is due to the need to preserve pipes from destruction as a result of transport loads.

Water networks equip shutoff valves- dampers and valves for shutting off individual sections of the network, water-handling equipment, fire hydrants, and sometimes - street water columns. Hydrants and dampers, as a rule, are installed in special prefabricated or brick wells covered with metal hatches.

According to technical conditions, the water pressure in the water supply network of settlements should not exceed 6 atm. To supply water to multi-story houses additionally equip local pumping stations.

The network may be annular(consisting of separate adjacent closed circuits-rings that can be turned off in case of an accident) and branched (dead end), in which, in the event of an accident in any section, the water supply to all sections of the network located behind the damage is interrupted. Therefore, branched networks can be equipped only in cases where interruptions in water consumption are permissible.

The width of the route of the water supply network must be at least 40 m on both sides of the axis when laying water conduits in an undeveloped area and 10 m in a built-up area.

In places of forced intersection of the water supply and sewer networks in the settlement, the water supply is designed above the sewer. The vertical distance between them is not less than 0.4 m.

When laying parallel water pipes at the same level as the sewer pipes, the distance between the pipelines must be at least 1.5 m if the diameter of the water pipes is not more than 200 mm and at least 3 m if the diameter of the water pipes is more than 200 mm.

When parallel laying water pipes below sewer pipes, the distance between the walls of pipelines in filtering soils should be at least 5 m. , in seismic regions, etc.

The location of cesspools of garbage pits and other similar objects at a distance of less than 20 m from water supply networks is not allowed.

To regulate the pressure and flow of water, create its reserve and equalize the schedule of operation of pumping stations, they build water towers and reservoirs.

Water tower consists of a water tank, usually cylindrical in shape and supporting structure(trunk). The regulatory role of the water tower is that during a decrease in water use, the excess water supplied by the pumping station accumulates in it and is consumed during increased water consumption. The height of the water tower (the distance from the surface of the earth to the bottom of the tank), as a rule, does not exceed 25 m, sometimes 30 m; tank capacity - from several tens of cubic meters to several thousand. Support structures are made mainly of steel, reinforced concrete, sometimes brick, tanks - mainly of reinforced concrete and steel.

water tank, unlike a water tower, does not have a supporting structure (trunk), but is installed on elevated terrain. Sometimes water tanks serve to store fire and emergency water supplies. Now the most common tanks are made of reinforced concrete.

The capacity of the tanks should ensure uninterrupted water supply during peak hours, as well as a supply of water in case of an emergency. The walls and bottom of underground tanks must be waterproof (reinforced concrete, brick). The bottom of the tank should be above the groundwater level. If necessary, it is lowered with the help of drainage.

The systems of centralized water supply of settlements are divided into three categories according to the degree of reliability of water supply, depending on the population:

I - more than 50 thousand people,

II -50-0.5 thousand people,

III - less than 0.5 thousand people.

Water supply for residential areas and industrial enterprises, can be quite comparable in terms of consumption volumes. Moreover, production systems sometimes consume more water than the entire population of a large city. Wastewater generated as a result of technological processes can be saturated with harmful impurities, and pose a threat - if not to humanity as a whole, then environment exactly.

As part of the struggle for the environment, engineers and technologists are trying to reduce water consumption at enterprises - and, accordingly, reduce the amount of wastewater by introducing circulating and closed systems at enterprises. The most effective of them will be discussed below. Get acquainted with the information presented, and watch the video in this article on the topic: “Industrial needs: water supply”.

Principles of creating production systems

To achieve a significant reduction in runoff, the construction of industrial water supply must be considered in conjunction with sewerage.

In the organization of water supply

Attention! The supply of water to industrial enterprises, and its discharge, should be a single system in which water is supplied in stages, it is discharged, and cleaned before reuse.

This is the first and most important condition creation of an efficient system of water consumption at enterprises. Schematically, it looks like the photo below.

So:

• The second principle should be the use in production cycles not of fresh water from sources, but of runoff from urban centralized systems that have undergone appropriate cleaning. Here, of course, we are not talking about food, pharmaceutical, or cosmetic industries.
• This refers to the water supply of petrochemical enterprises, or, for example, the water supply of ferrous metallurgy enterprises. Into their systems pure water from the primary source can only be supplied to compensate for water losses during the technological cycle.
• The third principle states that purification should be limited to restoring water or process solution to a quality that will allow them to be put back into production. For this purpose, local systems are created. closed type on which all industrial water supply is based.

Well, the fourth condition that will ensure the efficiency of the industrial water supply system at enterprises is the minimum energy and financial costs required to bring wastewater to a condition that allows it to be reused.

In design

Domestic and industrial water supply differ in that in the second case it is impossible to do something according to the "do it yourself" principle. The system must be designed - moreover, simultaneously with the main technology.

The project provides a scientific justification for the quality of water involved in technological process. Treated effluents are not considered here as an auxiliary resource, but as a technological solution to complete the production operation.

• Since the closed system of the enterprise is enough complex structure, it takes a lot of time and money to create it. The solution of such problems today is a priority both for newly developed systems and for reconstructed objects.
• Water circulation - that is, the ratio of the volumes of reused water in pulp and paper, chemical and metallurgical enterprises reaches almost 95%. And yet, these enterprises use a lot of fresh water needed to make up for losses.
• Pulp and paper mills consume the most - up to 500 m3, while the water supply of oil refineries absorbs half as much.
• So, designers have something to strive for - especially since modern technologies allow you to get water of almost any degree of purification from sewage.

The only thing that slows down the process of creating closed-loop systems is the high cost and organizational reasons. In any case, it is necessary to strive to ensure that economically closed systems have an advantage over other options.

Varieties of industrial water supply systems

What is industrial water supply in general, we explained. Now let's take a closer look at the purpose of industrial water pipes, and the principle of their work.

Perhaps the most important thing in the issue of industrial water supply is the purpose of water and its quality. This is where we'll start.

How do businesses use water?

Depending on the activities of enterprises, water can be spent by them not only for technical needs, but also for fire fighting, watering territories. In any production, there must also be a drinking water supply system.

After all, people working on it also need water - for drinking and washing. Accordingly, there may be several water pipes at the enterprise.

If we talk about drinking water supply (see), then in the vast majority, water supply to settlements and industrial enterprises is carried out from a common centralized network. Water consumption for such needs, and the design of the water supply system itself, is carried out in accordance with the norms 2.04.02-84.

Note! When the capacities of the city water supply are able to fully provide per-second flow, then the enterprise simply provides for the distribution of the network to all buildings and workshops. If the supply of a centralized water supply system does not provide the estimated need of the enterprise, then a pumping station with a storage tank is installed on its territory - and the supply pipeline is already being routed from it.

• For irrigation of the territory, water can be used by the enterprise both from the drinking water supply system and from production system which transports uncontaminated water.
• The consumption of water spent on fire extinguishing needs depends on the dimensions of the buildings and the degree of their fire resistance. But the category of fire hazard of production is of decisive importance here.
• Depending on the required volume, water for extinguishing a fire can be supplied both from a production or drinking system, and from a separately designed fire water supply (see).

Technical water quality

The technical water supply system of industrial enterprises - judging by the amount of water consumed, is the main one. Depending on the type of production, water can be used to create technological solutions, vaporization, product washing, cooling engineering equipment and much more.

At the same time, it can not only be saturated with various impurities, but also heat up significantly. All these changes make it possible to classify technologically waste water.

Here's what it looks like:

Attention! For negotiable and closed systems most often use water of I - III categories. The last three categories are used in direct-flow systems, which necessarily include: water treatment facilities that are used to prepare water of the required quality, pumping stations for its transportation - and, of course, a pipeline network with the required pressure.

Main production schemes

Now let's look at what industrial systems water supply have found the greatest use.

There are five of them in total, and we will give their brief characteristics in the table:

Conclusion

Large enterprises may have several dozen consumers, each of which will have individual requirements for the quality of the water used. At the same time, waste water can also vary greatly in composition. The creation of such systems is an extremely complex and very responsible matter, most often not having unambiguous solutions.

They are always designed individually - no standard projects it can't be here. Moreover, the pressures in the pipelines, and the mode of operation, for different consumers of the system may not coincide.

Therefore, water supply industrial facilities begins with the collection and systematization of initial data, grouping water consumers, determining the degree of reliability of supply for each. Only after this, enterprises begin to develop scheme options that are possible from the point of view of technical implementation.

Guide to the device of communications in the cottage

Construction of suburban housing, whether it is a small cottage or big house, always starts with the design engineering networks. As practice shows, homeowners are most interested in autonomous systems water supply. However, certain difficulties are associated with them: where to find a source, how to get water and deliver it to the house, and how much water do you need? The answers to these and many other questions are in the proposed material.

Water consumption calculation

The basis for the device of any water supply system is the calculation of water consumption. Two values ​​are considered basic - average and maximum (peak) consumption of resources.

In order to approximately estimate the water consumption, when making calculations, we will start from the standard of water consumption of 250 liters per person per day. If the site has a pond or pool, you should add 120 liters for every 10 square meters. m of its surface. Watering the lawn or garden - about 1200 more liters per 100 square meters. m.

The values ​​of the maximum water consumption are calculated by experts and are given in Table. 1.

Tab. 1. Maximum water consumption

Example:

Let's calculate the water consumption of a cottage in which a family of 4 lives. The cottage is located on a standard plot of 10 acres. On adjoining territory there is a garden (6 acres or 600 sq. m) and a pond (20 sq. m).

4 people, 250 liters each - 1000 liters per day (4 x 250 liters).

Watering the garden (600 sqm) – minimum 7200 liters per day (600 sqm x (1200/100) liters).

Pond (Pool) - 240 liters per day (2 x 120 liters).

Total daily water requirement: 1000 l + 7200 l + 240 l = 8440 l

Maximum demand when using a non-pressure tank:
1.2 m 3 / h (house) + 1.0 m 3 / h (garden and pool) \u003d 2.2 m 3 / h.

Wells and wells

After all the necessary calculations, the owner of a private house should arrange a source of water supply. Best Option- use groundwater, for which wells are drilled on the site or wells are dug (see Table 2).

Tab. 2. Brief characteristics various water sources

Whatever source of water supply the consumer would prefer, a pump will be needed to extract water from the depths. Ekaterina Semyonova , engineer of the Household Equipment Department of GRUNDFOS, the world's leading manufacturer of pumping equipment, recommends using professional equipment GRUNDFOS SQE series. These pumps start and stop automatically, maintain a constant pressure in the system, and have built-in protection against dry running, overload and power surges. “In shallow wells and wells, submersible pumps, such as the SBA automatic pumping unit, can be installed. Its advantage is the presence of a built-in flow sensor, pressure switch and check valve, which eliminates the need for additional devices, - continues to explain Ekaterina Semyonova . - Sometimes they use surface pumps that are mounted in the house. Such equipment is convenient for maintenance, but often inferior in efficiency to submersible models.”

Water quality

Before installing a water supply system, it is necessary to analyze chemical composition water from a source in any institution of the sanitary and epidemiological station. After receiving the results, the owner of the source should contact the organization that supplies water treatment equipment. Professionals will pick up smart decision to obtain drinking water, they will offer the optimal combination of components (mechanical cleaning and disinfection).

However, filtration systems are already struggling with the consequences of pollution, and not with its causes. There is always a risk of contamination of the source, for example, sewer water commercial buildings, industrial emissions, etc. To avoid trouble, the source from which water is extracted must be isolated - that is, the space between the casing pipe (or rings, if we are talking about a well) and the ground must be filled.

Lead to the house

After the well or well is ready, you need to organize the supply of water to the house. The water supply should work properly in winter, so experts recommend laying pipes 1.5 meters below zero (the average depth of soil freezing in the Moscow and Leningrad regions). If it is not possible to dig such deep trenches on the site, you can close the communications with a polypropylene sheath and additionally lay heating electric cables through the pipes. When using a self-regulating cable, the heat dissipation will vary depending on the ambient temperature.

Pipes laid outside the house are made of plastic low pressure(PND). Such products are designed specifically for outdoor installation and have already proven themselves both in the professional environment and among consumers.

It is also necessary to competently and efficiently make the introduction of pipes into the building. Special attention given to the waterproofing of communications to avoid problems with the flow of water.

Equipment

The task of the pump, whether it is borehole, well or surface, is not only to raise water, but also to create pressure in the system. As a rule, for private houses the pressure level is 2.5-3 atm. To measure and control the pressure in the house, a pressure gauge is installed, and a special valve is mounted on the inlet pipe to regulate the incoming liquid.

When the required pressure is created in the system and the water intake stops, the pressure sensor that the pump is equipped with sends a signal to stop the equipment. As soon as the tap opens, the pump turns on to maintain pressure. 'for more effective work the booster system may include a hydraulic storage tank. Such, for example, is part of the automatic surface pumping unit MQ series from GRUNDFOS, says Ekaterina Semyonova (GRUNDFOS). - First, water will be parsed from the storage tank, and only then the pump will turn on. Thanks to the tank, it is possible to reduce the number of equipment starts, which means extending its service life, so our company's specialists recommend installing it for both borehole and submersible pumps.”

Filters

Water extracted from the source, before entering the consumer must go through the stage of preparation. First, the liquid is subjected to mechanical cleaning. “When water is taken in a well or well, turbulences can be created that raise sand, clay, and stones from the bottom. To prevent unnecessary impurities from entering the system further, the equipment is equipped with strainers, explains Ekaterina Semyonova (GRUNDFOS). - It is better to give preference to pumps with a "fine" mesh. For example, the filter of the SB and SBA pumps has a mesh size of >1 mm, which allows even microscopic particles of sand and dirt to be retained.”

The liquid that has undergone primary treatment is sent to the water treatment system, where a coarse and fine filter or even a special filter is installed. biological station such as uv sterilizer. It is a metal case, inside of which there is a bactericidal lamp. Radiation penetrates the cells of living organisms and destroys DNA structures.

Additionally, you can install equipment for water softening - a tank into which salt is poured. If there are calcium or iron impurities in the natural liquid (up to 10 mg per liter), they will be deposited on the system filter.

Pipeline

Internal water supply networks are usually laid in basement while the tubes remain open. Of course, it is possible to “hide” communications by making strobes in the walls, but in this case, at the places where the fittings and threaded connections it is necessary to provide hatches for preventive examination and repair.

For intra-house water supply systems, polypropylene or metal-plastic pipes are usually used. The former are easy to install - no welding or additional materials. Pipe, angles and tees are melted with special equipment and fastened together. Metal-plastic pipe consists of three layers: plastic inside, aluminum in the middle, and plastic outside again, which protects against corrosion. A distinctive feature of such pipes - long term operation, up to 50 years. The only minus of metal-plastic is crimp or twisted fittings (the connecting part of the pipeline), which, when installed illiterately, begin to flow, and eventually break through them. The correct installation of fittings depends on the qualifications of the specialists who are involved in this.

It is recommended that all work on the installation of the water supply network be carried out by specialists. The information given in the article will help the consumer to control the progress of work, and after installation, independently monitor the functioning of the system.

The material was prepared by the press service of GRUNDFOS LLC