Optimal methods of water treatment at thermal power plants and thermal power stations. Purpose of water treatment for CHP

30.09.2019

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The main "enemy" of energy companies is water with a high content of hardness salts. That is why ion-exchange, sorption or membrane equipment at thermal power plants, state district power plants, thermal power plants is the basis of the enterprise's water treatment system.

Water purification and water treatment in the energy sector is one of the main stages in organizing the operation of a thermal power plant. Existing thermal power plants generate heat by heating water and then condensing the steam. It is from the initial composition of the make-up agent that the service life of the steam generator of a thermal power plant depends.

What is the difference between filters for CHP, GRES and TPP? And how to extend the service life of expensive equipment designed for heating residential buildings and industrial facilities?

The difference between water treatment systems for CHP, GRES and TPP

Most of the existing equipment of CHPPs, State District Power Plants and TPPs is made of metal alloys. That is why the main “enemy” of energy enterprises is the impurities prone to salt formation contained in make-up water (hardness and iron salts).

All existing thermal power plants can be divided into several types (Figure 1.). The main difference between CHP and CPP is that combined heat and power plants produce heat (in the form of hot water supplied to consumers) and electricity, while condensing heat and power plants generate only electricity due to a multiple condensation cycle.

Figure 1. Types of thermal power plants

Water at the state district power station and nuclear power plant is used for household and drinking needs (cooling of the reactor or active working zone). As a result, the water treatment system at such enterprises is limited to softening filters and desalters that trap hardness salts and iron oxides that destroy the pipeline system.

Differences in water treatment systems of various types of thermal power plants are due to the peculiarities of the technological process of the enterprise. So, the waste hot water of the thermal power plant is simply dumped. Thus, the most powerful filters of a steam turbine thermal power plant are used specifically for cleaning the incoming raw materials. Hot water from the CHPP is used to heat residential buildings and industrial buildings. That is why the water treatment system of the combined heat and power plant includes additional modules designed to trap contaminants that can lead to corrosion not only of boiler drums, but also of household communication lines.

Filtration systems for thermal power plants

The water treatment system of power enterprises includes several stages of pollution removal.

Table 2. Types of water treatment system for power plants

Water treatment stage	Used filters
Water clarification	Settling tanks and mechanical filters with the addition of coagulants and flocculants
Disinfection	Ozonation, chlorination
Water softening	Reagent sedimentation, cationic filters
Water desalination	Anion filters, calciner, electrodiadizer, reverse osmosis, evaporators
Water deaeration (removal of gaseous substances)	Thermal deaerators, vacuum deaerators, atmospheric deaerators
Boiler blowdown	Wash filters
Steam flush	Special reagents-desalting agents

In European thermal power plants, the loss efficiency is only 0.25% per day. Such high performance results are achieved through a combination of several traditional and innovative methods of desalination and purification of the raw materials used and make-up water. The service life of the equipment of thermal power plants under such conditions reaches 30-50 years.

Sources used:

1. "Environmentally safe thermal power plants". Electronic journal of the energy service company "Ecological Systems"

2. Kopylov A.S., Lavygin V.M. Water treatment in the energy sector

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Ministry of Education and Science of the Russian Federation

Branch of the federal state budgetary educational institution of higher professional education "South Ural State University" (national research

University) in Satka

Test

in the discipline "General Energy"

topic: "Chemical water treatment at a thermal power plant"

INTRODUCTION

Energy consumption is a prerequisite for the existence of mankind. The availability of energy available for consumption has always been necessary to meet human needs, increase the duration and improve the conditions of his life. The history of civilization is the history of the invention of more and more new methods of energy conversion, the development of its new sources and, ultimately, an increase in energy consumption. The first jump in the growth of energy consumption occurred when people learned how to make fire and use it to cook and heat their homes. During this period, firewood and the muscular strength of a person served as sources of energy. The next important stage is associated with the invention of the wheel, the creation of various tools, and the development of blacksmithing. By the 15th century medieval man, using draft animals, water and wind energy, firewood and a small amount of coal, already consumed about 10 times more than primitive man. A particularly noticeable increase in world energy consumption has occurred over the past 200 years since the beginning of the industrial era - it has increased 30 times and reached 14.3 Gtce/year in 2001. A man in an industrial society consumes 100 times more energy than a primitive man, and lives 4 times longer. In the modern world, energy is the basis for the development of basic industries that determine the progress of social production. In all industrialized countries, the pace of development of the energy industry outpaced the pace of development of other industries. Power plant - a power plant that serves to convert any energy into electrical energy. The type of power plant is determined, first of all, by the type of energy carrier. The most widespread are thermal power plants (TPPs), which use thermal energy released by burning fossil fuels (coal, oil, gas, etc.). Thermal power plants generate about 76% of the electricity produced on our planet. This is due to the presence of fossil fuels in almost all areas of our planet; the possibility of transporting organic fuel from the place of production to the power plant located near energy consumers; technical progress at thermal power plants, which ensures the construction of high-capacity thermal power plants; the possibility of using the waste heat of the working fluid and supplying consumers, in addition to electrical, also thermal energy (with steam or hot water), etc.

Depending on the source of energy, there are: - thermal power plants (TPP) using natural fuel; - hydroelectric power plants (HPP) using the energy of falling water of dammed rivers;

Nuclear power plants (NPPs) using nuclear energy; - other power plants using wind, solar, geothermal and other types of energy.

Our country produces and consumes a huge amount of electricity. It is produced almost entirely by the three main types of power plants: thermal, nuclear and hydroelectric power plants.

In Russia, about 75% of energy is produced at thermal power plants. TPPs are built in fuel extraction areas or in energy consumption areas. It is advantageous to build hydroelectric power stations on full-flowing mountain rivers. Therefore, the largest hydroelectric power plants are built on Siberian rivers. Yenisei, Angara. But cascades of hydroelectric power stations have also been built on the flat rivers: the Volga, the Kama. combined heat and power plant turbine water treatment

Nuclear power plants are built in areas where a lot of energy is consumed, and other energy resources are not enough (in the western part of the country).

The main type of power plants in Russia are thermal (TPP). These installations generate approximately 67% of Russia's electricity.

Their placement is influenced by fuel and consumer factors. The most powerful power plants are located in the places where fuel is extracted. Thermal power plants using high-calorie, transportable fuel are consumer-oriented.

1. THERMAL POWER PLANTS (CHP)

This type of power plants is designed for centralized supply of industrial enterprises and cities with thermal and electrical energy. Being, like IES, thermal stations, they differ from the latter in the use of heat from the steam “exhausted” in turbines for the needs of industrial production, as well as for heating, air conditioning and hot water supply. With such a combined generation of electrical and thermal energy, significant fuel savings are achieved in comparison with separate energy supply, i.e., electricity generation at CPP and heat from local boiler houses. Therefore, CHPs have become widespread in areas (cities) with high consumption of heat and electricity. In general, CHPs produce up to 25% of all electricity generated in the country.

Parts of the scheme, which are similar in structure to those for IES, are not shown here. The main difference lies in the specifics of the steam-water circuit and in the method of generating electricity.

Rice. 1. Features of the technological scheme of a station of the CHP type:

1 -- network pump; 2 -- network heater

As can be seen from fig. 1, steam for production is taken from intermediate turbine extractions after it has given off a significant part of the energy at a pressure of 10–20 kgf/cm2, while its primary parameters before the turbine are 90–130 kgf/cm2.

For heat supply, steam is taken at a pressure of 1.2-2.5 kgf / cm2 and enters the network heaters 2 (Fig. 1). Here it gives off heat to the network water and condenses. The condensate of the heating steam is returned to the main steam-water circuit, and the water pumped into the heaters by network pumps 1 is directed to the needs of heating.

It is clear that the greater the commercial heat supply (i.e. heat consumption) and the less heat is wasted away by circulating water, the more economical the process of generating electricity at a CHP plant.

In general, the CHP efficiency exceeds the efficiency of IES. Depending on the amount of heat consumption, it can be 50--80%.

If there is no or little heat consumption, the CHP plant can generate electricity in the condensing mode. However, in this mode, CHPP units are inferior in terms of technical and economic indicators to IES units.

The specificity of the electrical part of the CHPP is determined by the position of the station near the centers of electrical loads. Under these conditions, part of the power can be supplied to the local network directly at the generator voltage. For this purpose, a generator switchgear (GRU) is usually created at the station. Excess power is supplied, as in the case of CES, to the system at increased voltage.

An essential feature of the CHPP is also the increased capacity of thermal equipment compared to the electric capacity of the station, taking into account the production of thermal energy. This circumstance predetermines a higher relative consumption of electricity for own needs than in the case of IES.

2. CHEMICAL WATER TREATMENT AT CHPP

In thermal power engineering, the main heat carrier is water and the steam formed from it. The impurities contained in the water, which enter the steam boiler with feed water, and into the hot water boiler from the network, form low-thermal-conductive deposits and scale on the heat exchange surface, which heat-insulate the surface from the inside, and also cause corrosion. Corrosion processes, in turn, are an additional source of impurities entering the water.

As a result, the thermal resistance of the wall increases, heat transfer decreases, and, consequently, the temperature of the flue gases increases, which leads to a decrease in the efficiency of the boiler and excessive fuel consumption. With excessive temperature rises in the metal of pipes, their strength decreases, up to the creation of an emergency.

At low and medium pressures in drum boilers, impurities enter the steam only as a result of the entrainment of droplets of boiler water, that is, if the drying of the apparatus is not effective enough. At high pressures, impurities begin to dissolve in the vapor, and the more intensely, the higher the pressure, and, first of all, silicic acid.

Therefore, with increasing pressure, the requirements for the quality of feed and make-up water increase significantly. The requirements for the reliability of the water regime are formulated in the form of water regime standards in the rules for the technical operation of power plants and networks (PTE) and in the rules for the design and safe operation of steam and hot water boilers.

The presence of deposits makes it necessary to clean the equipment, which is a laborious and expensive operation. Thus, water treatment is a necessary attribute of any boiler room. The purity of water and steam in individual units and parts of the ducts of the boiler house, united by the general concept of the water regime of the boiler house, has a significant impact on the efficiency and reliability of its operation.

2.1 Water treatment at CHP

One of the most important issues in the energy sector has been and remains water treatment at thermal power plants. For energy companies, water is the main source of their work, and therefore very high requirements are imposed on its content. Since Russia is a country with a cold climate, constant severe frosts, the operation of a thermal power plant is something on which people's lives depend. The quality of the water supplied to the heat and power plant greatly affects its operation. Hard water results in a very serious problem for steam and gas boilers, as well as steam turbines of thermal power plants, which provide the city with heat and hot water. In order to clearly understand how and what exactly hard water negatively affects, it would not hurt to first understand what a CHP is? And with what it "eat"? So, a CHPP - a heat and power plant - is a kind of thermal power plant that not only provides heat to the city, but also supplies hot water to our homes and enterprises. Such a power plant is designed as a condensing power plant, but differs from it in that it can take part of the thermal steam after it has given up its energy.

Steam turbines are different. Depending on the type of turbine, steam with different indicators is selected. Turbines in the power plant allow you to adjust the amount of steam taken. The steam that has been extracted is condensed in the network heater or heaters. All energy from it is transferred to network water. Water, in turn, goes to peak water heating boiler houses and heat points. If the steam extraction paths are blocked at the CHPP, it becomes a conventional IES. Thus, the heat and power plant can operate according to two different load schedules:

thermal graph - direct proportional dependence of the electrical load on the thermal;

electrical graph - there is either no heat load at all, or the electrical load does not depend on it. The advantage of CHP is that it combines both heat and electricity. Unlike IES, the remaining heat does not disappear, but is used for heating. As a result, the efficiency of the power plant increases. For water treatment at CHPPs, it is 80 percent versus 30 percent for IES. True, this does not speak of the efficiency of the heat and power plant. Here in the price there are other indicators - the specific generation of electricity and the efficiency of the cycle. The peculiarities of the location of the CHP should include the fact that it should be built within the city. The fact is that the transfer of heat over distances is impractical and impossible. Therefore, water treatment at CHPPs is always built near consumers of electricity and heat. What is the water treatment equipment for CHP? These are turbines and boilers. Boilers produce steam for turbines, turbines produce electricity from steam energy. The turbogenerator includes a steam turbine and a synchronous generator. Steam in turbines is obtained by using fuel oil and gas. These substances heat the water in the boiler. The pressurized steam turns the turbine and the output is electricity. Waste steam is supplied to homes in the form of domestic hot water. Therefore, the exhaust steam must have certain properties. Hard water with a lot of impurities will not allow you to get high-quality steam, which, moreover, can then be supplied to people for use in everyday life. If the steam is not sent to supply hot water, then it is immediately cooled in the thermal power plant in cooling towers. If you have ever seen huge pipes at thermal stations and how smoke pours from them, then these are cooling towers, and smoke is not smoke at all, but the steam that rises from them when condensation and cooling occurs. How does water treatment work on fuel cells? The most affected by hard water is the turbine and, of course, boilers that convert water into steam. The main task of any thermal power plant is to get clean water in the boiler. Why is hard water so bad? What are its consequences and why do they cost us so much? Hard water differs from ordinary water by its high content of calcium and magnesium salts. It is these salts that, under the influence of temperature, settle on the heating element and the walls of household appliances. The same applies to steam boilers. Scale forms at the heating point and the boiling point along the edges of the boiler itself. Descaling in the heat exchanger in this case is difficult, because. scale builds up on huge equipment, inside pipes, all kinds of sensors, automation systems. Flushing the boiler from scale on such equipment is a whole multi-stage system that can even be carried out when disassembling the equipment. But this is in the case of a high density of scale and its large deposits. The usual remedy for scale in such conditions, of course, will not help. If we talk about the consequences of hard water for everyday life, then this is the impact on human health and the rise in the cost of using household appliances. In addition, hard water is very bad in contact with detergents. You will use 60 percent more powder, soap. Costs will grow by leaps and bounds. Water softening was therefore invented to neutralize hard water, you put one water softener in your apartment and forget that there is a descaling agent, a descaling agent.

Scale is also characterized by poor thermal conductivity. This lack of it is the main cause of breakdowns of expensive household appliances. A thermal element covered with scale simply burns out, trying to give off heat to the water. Plus, due to the poor solubility of detergents, the washing machine must be additionally turned on for rinsing. These are the costs of water and electricity. In any case, water softening is the surest and most cost-effective way to prevent scale formation. Now imagine what is water treatment at a thermal power plant on an industrial scale? There, the descaler is used by the gallon. Flushing the boiler from scale is carried out periodically. It happens regularly and repair. To make descaling more painless, water treatment is needed. It will help prevent the formation of scale, protect both pipes and equipment. With it, hard water will not exert its destructive effect on such an alarming scale. If we talk about industry and energy, then most of all hard water brings trouble to thermal power plants and boiler houses. That is, in those areas where there is direct water treatment and heating of water and the movement of this warm water through water supply pipes. Water softening is as necessary here as air. But since water treatment at a thermal power plant is work with huge volumes of water, water treatment must be carefully calculated and thought out, taking into account all sorts of nuances. From the analysis of the chemical composition of water and the location of a particular water softener. In CHP, water treatment is not only a water softener, it is also equipment maintenance after. After all, descaling will still have to be done in this production process, with a certain frequency. More than one descaler is used here. It can be formic acid, and citric, and sulfuric. In various concentrations, always in the form of a solution. And they use one or another solution of acids, depending on what components the boiler, pipes, controller and sensors are made of. So, which energy facilities need water treatment? These are boiler stations, boilers, this is also part of the CHPP, water heating installations, pipelines. Pipelines remain the weakest points, including CHPs. Scale accumulating here can also lead to depletion of pipes and their rupture. When the scale is not removed in time, it simply does not allow water to pass through the pipes normally and overheats them. Along with scale, the second problem of equipment in CHP is corrosion. It also cannot be left to chance. What can lead to a thick layer of scale in the pipes that supply water to the CHP? This is a difficult question, but we will answer it now knowing what water treatment at a CHP is. Since scale is an excellent heat insulator, the heat consumption increases sharply, while the heat transfer, on the contrary, decreases. The efficiency of boiler equipment drops significantly, and as a result, all this can lead to rupture of pipes and explosion of the boiler.

Water treatment at a thermal power plant is something that cannot be saved on. If in everyday life, you still think whether to buy a water softener or choose a descaler, then such bargaining is unacceptable for thermal equipment. At thermal power plants, every penny is counted, so descaling in the absence of a softening system will cost much more. And the safety of devices, their durability and reliable operation also play a role. Descaled equipment, pipes, boilers work 20-40 percent more efficiently than equipment that has not been cleaned or works without a softening system. The main feature of water treatment at thermal power plants is that it requires deeply demineralized water. To do this, you need to use precise automated equipment. In such production, reverse osmosis and nanofiltration, as well as electrodeionization, are most often used. What stages does water treatment in the energy sector include, including at a heat and power plant? The first stage includes mechanical cleaning from all kinds of impurities. At this stage, all suspended impurities are removed from the water, up to sand and microscopic rust particles, etc. This is the so-called coarse cleaning. After it, the water comes out clean for the human eye. Only dissolved hardness salts, ferrous compounds, bacteria and viruses, and liquid gases remain in it.

When developing a water treatment system, it is necessary to take into account such a nuance as the source of water supply. Is it tap water from public water systems or is it water from a primary source? The difference in water treatment is that the water from the water supply systems has already passed the primary treatment. Only hardness salts should be removed from it, and deferrized if necessary. Water from primary sources is absolutely untreated water. That is, we are dealing with a whole bouquet. Here it is imperative to carry out a chemical analysis of water in order to understand what impurities we are dealing with and what filters to install to soften the water and in what sequence. After rough cleaning, the next stage in the system is called ion-exchange demineralization. An ion exchange filter is installed here. Works on the basis of ion-exchange processes. The main element is an ion exchange resin, which includes sodium. It forms weak bonds with resin. As soon as hard water at a thermal power plant enters such a softener, the hardness salts instantly knock sodium out of the structure and firmly take its place. Restoring such a filter is very simple. The resin cartridge is moved to the recovery tank, where the saturated brine is located. Sodium takes its place again, and hardness salts are washed into the drain. The next step is to obtain water with desired characteristics. Here, a water treatment plant is used at a thermal power plant. Its main advantage is the receipt of 100% pure water, with the specified indicators of alkalinity, acidity, mineralization level. If the company needs industrial water, then the reverse osmosis plant was created just for such cases.

The main component of this installation is a semi-permeable membrane. The selectivity of the membrane varies, depending on its cross section, water with different characteristics can be obtained. This membrane divides the tank into two parts. One part contains a liquid with a high content of impurities, the other part contains a liquid with a low content of impurities. Water is launched into a highly concentrated solution, it slowly seeps through the membrane. Pressure is applied to the installation, under the influence of it, the water stops. Then the pressure is sharply increased, and the water begins to flow back. The difference between these pressures is called osmotic pressure. The output is perfectly pure water, and all deposits remain in a less concentrated solution and are discharged into the drain.

Nanofiltration is essentially the same reverse osmosis, only low-pressure. Therefore, the principle of operation is the same, only the water pressure is less. The next stage is the elimination of gases dissolved in it from the water. Since CHP plants need clean steam without impurities, it is very important to remove oxygen, hydrogen and carbon dioxide dissolved in it from the water. The elimination of impurities of liquid gases in water is called decarbonation and deaeration. After this stage, the water is ready for supply to the boilers. Steam is obtained at exactly the concentration and temperature that is needed.

As can be seen from all of the above, water treatment in a CHP is one of the most important components of the production process. Without clean water, there will be no good quality steam, which means there will be no electricity in the right amount. Therefore, water treatment in thermal power plants should be dealt with tightly, trust this service exclusively to professionals. A properly designed water treatment system is a guarantee of long-term equipment service and quality energy supply services.

2.2 Chemical water treatment

Most modern enterprises use wastewater treatment plants to filter wastewater for later use. Due to the presence in them of a large number of harmful substances - the remnants of technogenic production, simple mechanical purification is not enough. For this reason, for complete chemical water purification, technologies and installations are used that purify the liquid using chemical reagents. Proper use of such methods allows you to achieve very high results and eliminate pollution of any type. Depending on the data of the chemical and biological analysis of the liquid, the appropriate types of chemical, biochemical substances are used for water purification, which maximally meet all the requirements.

Using the obtained data on the composition of H2O, scientists determine in a laboratory way what chemical reactions occur during water purification with a particular concentration of reagents. Since the substance used as a reagent is active in this process, in order to avoid its overdose, the proportions proposed by specialists should be strictly observed. In some cases, the use of such additives is impossible because the damage from them will be much greater than the benefits. In such situations, biologically active substances are used that can oxidize almost all contaminants without harming the environment. Before using them, it will not be superfluous to find out in more detail what analyzes are performed during aerobic biochemical water treatment. One of the most common studies is biochemical oxygen demand, which indicates how much O2 is enough for microorganisms for their normal functioning and oxidation of harmful substances. In addition to this indicator, the chemical and biological analysis of the liquid is also taken into account.

Often in the drains you can find chromium - a toxic substance that causes allergic reactions and is very dangerous for the human body. Its neutralization is also important, as well as desalination, deferrization of H2O. To do this, it is necessary to carry out chemical purification of water from chromium by electrocoagulation. The liquid is subjected to electrophoresis, as a result of which the chromium molecule is divided into anions and cations. Aluminum and iron hydroxides, which have a high sorption capacity, attract them, forming an insoluble flocculent precipitate. The advantages of this method are the absence of reagents acting as salts.

Chemical purification of water from iron and calcium

One of the most common contaminants is iron oxide, which is characterized by a specific color and metallic taste. In the case when its amount is small, oxygen can be used as a reagent. Often in this way water is purified from a well containing iron oxide. The essence of this method is that with the help of the H2O compressor, O2 is saturated. For the successful flow of the reaction between iron and oxygen, a catalyst, magnesium, is used. The result of the reaction is the production of ferric iron, which is easily retained by mesh filters.

In cases where it is necessary to perform deironing, softening, neutralization and chemical purification of rusty water in a well, stronger reagents are used. These include sodium hypochlorite, which oxidizes almost all salts, metals and organic substances. If the liquid is not used in production in the future, and its filtration is necessary to return it to the natural environment, it is worth using more gentle methods. Particular attention should be paid to the industrial purification of water from thermal power plants with chemical reagents from calcium, which protects pipes from the formation of limescale. Even a small layer of scale on the pipes contributes to a decrease in the heat transfer coefficient and an increase in fuel consumption. To solve this problem, the liming method can be used, when a solution of slaked lime with a pH level of not more than 10 is added to the liquid. As a result, the following example of a chemical water purification reaction can be observed:

Ca(HCO3)2 + Ca(OH)2 = 2CaCO3 + 2Н2O Mg(HCO3)2 + 2Ca(OH)2 = Mg(OH)2 + 2СaCO3 + 2Н2O.

As a result, insoluble salts are formed, which are then removed from the tank. It is very important that the reactions of the chemical water treatment system, as well as the control of temperature and pressure, are carried out constantly. Otherwise, there may be difficulties in the disposal of sludge, an increase in the turbidity of the liquid.

The choice of reagents for the chemical treatment of industrial water largely depends on the nature of the pollution, as well as on the financial capabilities of the enterprise. Chemical water treatment is combined with the efforts of many organizations using sodium hypochlorite, which is explained by its high efficiency and low cost. According to the results of filtration, it can compete with the ozonation method, which is absolutely harmless to humans, but its cost will be much higher. Many plants use boiler plants that require thorough filtration of H2O prior to use. This need is due to protection against the formation of limescale and corrosion. Chemical water treatment of a boiler plant is carried out by means of electrochemical oxidation or by adding a special anti-scale solution to the liquid. The first method is safer, since it does not use reagents, and the removal of salts occurs due to the action of a magnetic field on them. The second method is not used so often and is used for prevention.

REFERENCES

1. Gitelman L.D., Ratnikov B.E. Energy business. - M.: Delo, 2006. - 600 p.

2. Fundamentals of energy saving: Proc. allowance / M.V. Samoilov, V.V. Panevchik, A.N. Kovalev. 2nd ed., stereotype. - Minsk: BSEU, 2002. - 198 p.

3. Standardization of energy consumption - the basis of energy saving / P.P. Bezrukov, E.V. Pashkov, Yu.A. Tsererin, M.B. Plushevsky //Standards and quality, 1993.

4. I.Kh.Ganev. Physics and calculation of the reactor. Textbook for universities. M, 1992, Energoatomizdat.

5. Ryzhkin V. Ya., Thermal power stations, M., 1976.

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Disadvantages of water treatment at CHP

The negative aspect of the water treatment process is the formation of an insoluble precipitate formed when water is heated. It is very difficult to remove. During getting rid of plaque, the whole process stops, the system is disassembled, and only after that it is possible to clean hard-to-reach places with high quality. What harms scale? It interferes with thermal conductivity and, accordingly, costs increase. Know that even with a small amount of plaque, fuel consumption will increase.

It is not possible to descale continuously, but it must be done every month. If this is not done, then the scale layer will constantly increase. Accordingly, cleaning equipment will require much more time, effort and material costs. In order not to stop the whole process and not incur losses, it is necessary to regularly monitor the cleanliness of the system.

Signs of a need for cleaning:

there will be sensors that protect the system from overheating;
heat exchangers and boilers are blocked;
explosive situations and fistulas occur.

All this is the negative consequences of scale not removed in time, which will lead to breakdowns and losses. In a short time, you can lose equipment that costs a lot of money. Descaling entails a deterioration in the quality of the surface. Water treatment does not remove scale, only you can do this using special equipment. With damaged and deformed surfaces, scale forms faster in the future, and a corrosive coating also appears.

Water treatment at mini combined heat and power plants

The preparation of drinking water includes a lot of processes. Before starting water treatment, a thorough analysis of the chemical composition should be carried out. What does he represent? Chemical analysis shows the amount of liquid that needs daily cleaning. Indicates those impurities that should be eliminated first. Water treatment at mini combined heat and power plants cannot be carried out in full without such a procedure. Water hardness is an important indicator that must be determined. Many problems in the state of water are associated with its hardness and the presence of deposits of iron, salts, silicon.

A big problem that every CHP plant faces is the presence of impurities in the water. These include potassium and magnesium salts, iron.

The main task of the CHPP is to provide residential facilities of the settlement with heated water and heating. Water treatment at such enterprises involves the use of softeners, additional filter systems. Each stage of purification includes the passage of water through filters, without which the process is impossible.

Stages of water treatment:

The first stage is clarification. First of all, the water is clarified, since it enters the mini-CHP system very dirty. At this stage, settling tanks and mechanical filters are used. The principle of operation of sedimentation tanks is that solid impurities go down. The filters consist of stainless gratings and have different sizes. Large impurities are captured first, followed by medium-sized gratings. The smallest impurities are captured last. Also important is the use of coagulants and flocculants, with the help of which various kinds of bacteria are destroyed. By rinsing with clean water, these filters can be ready for the next use.
The second stage is disinfection and disinfection of water. At this stage, an ultraviolet lamp is used, which provides complete irradiation of the entire volume of water. Thanks to ultraviolet, all pathogens die. The second stage also includes disinfection, during which bleach or harmless ozone is used.
The third stage is water softening. It is characterized by the use at home of ion-exchange systems, electromagnetic softeners. Each has its own advantages and disadvantages. Reagent settling is popular, the disadvantage of which is the formation of deposits. These insoluble impurities are very difficult to remove later.
The fourth stage is water desalination. At this stage, anionic filters are used: calciners, electrodiadizers, reverse osmosis and nanofiltration. The desalination process is possible by any of the above standard methods.
The fifth stage is deaeration. This is a mandatory step that follows after fine cleaning. Systems for cleaning from gas impurities are of the vacuum type, as well as atmospheric and thermal. As a result of the action of deaerators, dissolved gases are eliminated.

Perhaps these are all the most important and necessary processes that are carried out for make-up water. The following are general processes for preparing the system and its individual components. After all of the above, the boiler is purged, during which washing filters are used. At the end of the water treatment, the mini-CHP includes steam flushing. During this process, chemical reagents are used that demineralize water. They are quite varied.

In Europe, water treatment at mini-CHPs has found a very wide application. Due to the quality of this process, the efficiency increases. For the best effect, it is necessary to combine traditional, proven cleaning methods and new, modern ones. Only then can a high result and high-quality water treatment of the system be achieved. With proper use and constant improvement, the mini CHP system will serve for a long time and with high quality, and most importantly, without interruptions and breakdowns. Without changing the elements, and without repairs, the service life is from thirty to fifty years.

Water treatment systems for CHP

Some more important information that I would like to convey to the reader about the water treatment system at thermal power plants and their water treatment plants. In this process, different types of filters are used, it is important to responsibly choose his choice and use the right one. Often, several different filters are used, which are connected in series. This is done so that the stages of water softening and removal of salts from it go well and efficiently. The use of an ion exchange plant is most often carried out in the treatment of water with high hardness. Visually, it looks like a tall cylindrical tank and is often used in industry. The composition of such a filter includes another one, but of a smaller size, it is called a regeneration tank. Since the operation of the CHP is continuous, the installation with an ion exchange mechanism is multi-stage and includes up to four different filters. The system is equipped with a controller and one control unit. Any filter used is equipped with a personal recovery tank.

The task of the controller is to monitor the amount of water that has passed through the system. It also controls the volume of water purified by each filter, registers the cleaning period, the amount of work and its speed for a certain time. The controller transmits the signal further down the installation. Water with high hardness goes to other filters, and the used cartridge is recovered for later use. The latter is removed and transferred to the tank for regeneration.

Scheme of water treatment at a thermal power plant

The basis of the ion exchange cartridge is resin. It is enriched with mild sodium. When water comes into contact with resin enriched with sodium, transformations and reincarnations take place. Sodium is replaced by strong hard salts. Over time, the cartridge is filled with salts, and the recovery process takes place. It is transferred to the recovery tank, where the salts are located. The solution, which includes salt, is very saturated (≈ 10%). It is thanks to this high salt content that stiffness is eliminated from the removable element. After the flushing process, the cartridge is refilled with sodium and is ready for use. Waste with a high salt content is re-cleaned and only then can it be disposed of. This is one of the disadvantages of such installations, since it requires significant material costs. The advantage is that the rate of water purification is higher than that of other similar installations.

Water softening needs special attention. If the water treatment is not done with high quality and saved, then you can lose a lot more and get costs that are incommensurable with the savings on water treatment.

There was a question of pre-training at the CHP!? Don't know where to turn?

It is somehow difficult to imagine thermal power plants without working with water. The main driving force in such production is just water. And in order for the CHP, that is, the heat and power plant to work without interruption, it does not hurt to take care of the quality of the water entering it in advance. And with the current water treatment water treatment at CHP will not be superfluous, but extremely necessary and important.

How are they doing?

The difference in the operation of boiler houses in Russia and, for example, European Denmark, is significant. But we can safely say that Europeans do not have to work in such difficult weather conditions. In the same place in Denmark, they don’t work at temperatures over thirty, both in hellish heat and in wild cold. Any CHP plant will work longer and better if it is properly operated and if the water supplied to it meets the requirements of the equipment.

At one time, a wave of updates and requirements for make-up water swept through Europe. Today they work, for example, in Denmark for water with a temperature of thirty-five to almost two hundred degrees. At the same time, the requirements for the operation of CHP clearly state that aluminum parts cannot be mounted. The reason is that at a level of acid-base balance equal to 8.7, corrosion processes will begin without fail in the system. Such CHPPs operate on softened or demineralized deaerated water. Moreover, for each type of water, the following input requirements must be met:

Of all the impurities that can only be found in water, the greatest danger directly to heating plants will be precisely the hardness of the water. The presence of a significant excess of the threshold of lime will be a direct cause of the formation of limescale on the walls of the equipment. And moreover, this scum will hit everything with which it will cooperate.

If there was no such great harm from scale, then no one would pay attention to it, but in fact, it settles everywhere:

Heat exchangers;
pipes;
Cauldrons.

The result of such contact is the poor operation of the boiler house or CHP in the complex. Fuel consumption is growing exponentially. And the thicker the scale, the more difficult it is to heat the surface. This is the main reason for such an urgent need for water softening. If the scale exceeds a certain threshold, then the heat from the heating element or the walls of the equipment will no longer flow into the water. At the same time, heat cannot be absorbed somewhere. It begins to accumulate, and not just anywhere, but directly in the metal of the walls or the heating element. Even the most hardened metal will not be able to withstand constant heating for a long time. Crooked pipes, as if torn from the inside, these are the consequences of just a millimeter layer of scale. Therefore, scale in thermal power plants is treated very reverently. The layer is thin, and the boiler can easily break. And that's a big expense. Therefore, water can either be desalinated or softened. And the difference between these concepts is small, but there is. Softening involves the elimination of two mineral salts, and desalting involves the complete elimination of salts. That is, the result is a distillate.

But no matter how the water is cleaned and treated, a certain percentage of raw water can still enter the water treatment system. Tanks can leak, and while the same electromagnetic device does not work, because. water is at rest, it is also possible for some hard water to enter the system. To neutralize such water, chemicals are used in the water treatment system at the CHP plant. They are injected into the water supply system, the salts form an easily removable precipitate that is easy to remove from the equipment. And he does not stick to the walls.

By the way, scale is also harmful because, as a result of poor thermal conductivity, corrosion appears on surfaces, the metal then becomes almost soft. He then overheats, becomes more susceptible to water. The percentage increase in surface heating temperature due to scale can reach up to 50 percent!

The next enemy of the equipment of the combined heat and power plant, stimulated by scale, is, as mentioned above, corrosion. And now we have to solve not one, but two big problems at once. In order for the metal to begin to carrode, it is necessary that air is freely available to its surface. Therefore, in fact, for the operation of circulating water, they buy. And the higher the percentage of oxygen, the higher the probability of formation of corrosion centers.

Filters and a new interpretation of water treatment at thermal power plants

In Russian realities, they prefer to deal more with corrosion than with its origins. Only in boiler houses, where there is the possibility of water treatment at the CHP and not only includes degassing. In Denmark, for example, not every CHP plant has such installations. In most cases, oxygen is dealt with by adding conventional chemicals. Although in Russia today many central plants work with conventional chemical softening or preventive washings, because there is simply no money for a full-fledged good water treatment system.

An important indicator of the correct is the pH level. And when it is circulating water, its value should not go beyond the range from nine and a half to ten. The fork is quite small. But on the other hand, the high value of this indicator guarantees the protection of iron surfaces. Moreover, the dependence of the level of acid-base balance on the corrosion of metals can also be applied to brass, copper or zinc. But when working with this indicator, you need to remember about the work of alkali. For example, an indicator above ten will again lead to the risk of corrosion, zinc from brass will begin to be massively washed out.

The main work of proper water treatment at CHP plants is performed by filtering units. The system will work best if not only dissolved metal salts, but also solid impurities are eliminated from it. This will make it possible not only to prevent the formation of scale and corrosion, but also to slow down the wear of the equipment. Yes, and bottlenecks in the system, the pumps will be safer.

Therefore, water treatment systems are a complex treatment with mechanical filters and softeners. Moreover, cleaning can be either complete or partial. Moreover, the system is not mounted on the main pipeline, which does not interfere with the normal continuous circulation of water. It is better, of course, when the filtration unit can be easily dismantled and cleaned. In the event that water is reused, it is better to mount the treatment system directly on the main pipe. But even here there should be sensors that, in the event of a clogged one of the filters, will quickly forward the flow through another circuit, and signal the problem to the control center.

Today, in order to save money, they began to massively use plastic as the main material for softening installations. But, unfortunately, while the hopes placed on him, he does not justify. The use of stainless steel seems to be more promising. Moreover, the problem with microbacteria has not yet been completely eliminated.

The trouble with plastic is that it easily concentrates oxygen. And therefore, the installation of unprotected pipelines becomes completely unprofitable, because. corrosion will begin to progress in the system and very quickly. But today there are special barrier devices that help remove oxygen from plastic with almost a hundred percent probability.

The next problem that is still being fought is bacteria. No matter how they tried to remove them. And most importantly, even soft purified water does not save, because the reagent can be put more than usual, so it turns out that the water begins to rot, the bacteria spread very quickly. In addition, bacteria are sand, dirt that accidentally got into the heating system. A special expanse of bacteria occurs inside the water supply systems, here they accumulate and can give the water an unpleasant odor. Bacteria can be eliminated by chemical reactions. Disinfection is by far the most effective and affordable way to eliminate bacteria from your heating plant.

Stainless steel has become one of the features of the new water supply systems for boiler houses and insulation. easier to tolerate bacterial plaque, but does not tolerate temperature and chloride compounds. When planning to mount such an installation, it is imperative to do a water analysis in order to know which one to choose. Yes, and the percentage of chloride is so awesome for stainless steel, it also does not hurt to find out. And in no case should such a surface be washed with perchloric acid. It will destroy the protective film of stainless steel.

As you can see, only careful preparation will help establish the correct water treatment system. And then it will always be warm in the houses of the inhabitants.