In our latitudes it is impossible to do without heating. Too cool autumn and spring, long winter leave no choice - all rooms have to be heated to create comfortable conditions life. At the same time, along with heat, hot water is also supplied to apartments, organizations and enterprises.
To provide heat supply services, in accordance with the law, an appropriate agreement must be concluded between the supplier and the consumer.
Space heating systems are divided into open or closed.
At the same time, heating also happens:
- centralized (when heating is provided by one boiler house for the whole microdistrict);
- local (installed in a separate building or serving a small complex of buildings).
The difference between closed systems and open ones is quite significant. The latter involves supplying heated water to consumers' homes while taking it directly from the heating network.
Open heating system
In this format, boiling water is sent to the water supply directly from the heating pipes, which allows you to completely avoid complete consumption even if its entire volume is taken away. During the USSR this principle the work of approximately half of all heating networks was based. This popularity was due to the fact that the scheme helped to use energy resources more economically and significantly reduce heating costs in winter period and hot water supply.
However, this method, supplying heat and boiling water residential buildings, has many disadvantages. The thing is that very often heated water, due to its dual purpose, does not meet sanitary and hygienic standards. The coolant can circulate through metal pipes enough long time before it hits the taps. As a result, it often changes its color and becomes bad smell. In addition, employees of sanitary and epidemiological services have repeatedly identified dangerous microorganisms in it.
The need to filter such water before feeding it into the hot water supply system greatly reduces the efficiency and increases the cost of heating. At the same time, until the current time, there is no real effective way purification of such water. The significant length of pipelines actually makes this procedure useless.
The circulation of water in such a system occurs due to the consideration of thermodynamic processes in the design. The heated liquid rises and leaves the heater due to increased pressure. At the same time, cool water creates a slightly lower pressure at the inlet to the boiler. This is what allows the coolant to move independently through the communications.
Water, like any other liquid, increases in volume when heated. Therefore, in order to prevent excessive load on heating networks, their design must include a special open expansion tank located above the level of the boiler and pipes. Excess coolant is squeezed out there. This gives grounds to call such a system open.
Heating in in this case occurs up to 65 degrees Celsius, and then through water taps the water flows directly into consumers’ homes. This system allows the installation of inexpensive, simple faucets.
Due to the fact that to predict how much hot water will be used is impossible, it is always supplied taking into account the highest consumption.
Heat supply systems operating in a closed circuit - what is it?
The difference between this scheme of centralized heating of houses and the previous one is that hot water is used exclusively for heating. Hot water supply is provided through a separate circuit or individual heating devices.
The coolant circulates in a closed circle; Any minor losses that occur are compensated for by automatic pumping when there is a loss of pressure.
Currently, the use of energy efficient technologies is one of the priorities in the housing and communal services sector, as it contributes to more economical use resources, reducing tariffs for housing and communal services and improving the quality of services provided. The issue of energy efficiency is especially relevant for Russia, where the wear and tear of fixed assets in the housing and communal services sector has already exceeded 60%. On average in our country, the wear and tear of boiler houses is 54.5%, public water supply networks - 65.5%, sewerage - 62.5%, heating networks - 62.8%, electrical networks in housing and communal services - 58.1%. Therefore, the accident rate of this infrastructure is growing rapidly. At the same time, the Russian system district heating is the largest in the world. Russia accounts for up to 45% of the world's centralized thermal energy production. In 2010, the Russian Ministry of Energy developed State program Russian Federation “Energy saving and increasing energy efficiency for the period until 2020” (“GPEE-2020”). As part of the implementation of the program, in many regions the fixed assets of housing and communal services are being updated: existing heating networks, central heating and heating substations, and boiler houses are being modernized.
One of the methods for increasing energy efficiency in the housing and communal services sector is to close the hot water supply system using heat exchange equipment. According to clause 8 of Art. 29 of the Federal Law of July 27, 2010 N 190-FZ “On Heat Supply”, from January 1, 2022, the use of centralized open heat supply systems (hot water supply) for the needs of hot water supply, carried out by selecting coolant for the needs of hot water supply, is not allowed. Despite a number of costs that will need to be incurred when switching to a closed hot water supply system, such a transition will ultimately be beneficial for both heating networks and consumers themselves.
Advantages of switching to a closed connection scheme for hot water supply systems
for heating networks:
- increasing the service life of hot water boilers, main and district heating networks,
- reducing the load on the heating network make-up system,
- compliance of water quality with sanitary standards established by SNiP 2.04.01-85,
- stable hot water temperature.
for consumers:
- reduction in payment for DHW services and compliance of payment with actual water consumption,
- stable hot water temperature,
- compliance of hot water quality with sanitary standards.
Let's take a closer look at the key advantages.
The quality of hot water meets sanitary standards.
The quality of hot water at consumer water collection points must comply with drinking water standards in accordance with SNiP 2.04.01-85*.
With a closed heat supply system, the heated water from consumers almost always complies with GOST standards for drinking water, because The city water supply works at a standstill.
At open system heating supply, the acute issue is that the consumer receives water of adequate quality. What is the reason? The operating mode of such a system is continuous circulation with repeated passage of hot water through numerous heating devices. The latter are a source of pollution and deterioration in the quality of drinking (network) water in terms of organoleptic indicators: color, transparency, iron content, development of unfavorable microflora and the appearance of odor. This is especially clear at the beginning heating season during mass launch of heating systems. It is difficult to combat these phenomena in operational conditions.
Reduced costs for preparing make-up water and pumping coolant.
With an open hot water system, the consumption of make-up water increases sharply, since it is necessary to replenish the consumed water by consumers. Heating networks in closed and open systems are recharged through the operation of make-up pumps and make-up water treatment plants. IN open circuit their required productivity is 10-30 times greater than in a closed one. As a result, with an open system, capital investments in heat sources are large.
After reconstruction
Hot water at a given temperature is obtained by heating cold tap water in a heat exchanger. A low-capacity circulation line ensures a constant set temperature in the pipes near the mixers, eliminating the need to drain expensive heated water into the sewer system. tap water as long as its temperature is not too high. When using these solutions, energy savings are up to 15% with associated savings in water from the water supply. The use of circulation allows you to have a constant flow of coolant on both sides of the heat exchanger. This significantly increases the service life of heat exchangers without contamination by deposits.
In each case, the choice between open and closed systems must be justified by technical and economic calculations, taking into account all parts of the heat supply system. Usually, when calculating the economic efficiency of closing a hot water supply circuit, the Ridan company provides a feasibility study of the project. Let us give an example of such a calculation performed for an object in Khabarovsk.
Feasibility study for the DHW circuit closure project (shortened version)
The purpose of the feasibility study: justification for closing the hot water supply system at a design capacity of 0.19 Gcal/h.
The existing DHW connection scheme is open.
The proposed option is considering a transition to a closed DHW scheme.
As an option for transition from an open to a closed circuit, it is proposed to install collapsible plate heat exchangers “Ridan” NN#07 in the amount of 2 pieces. 1 working, 1 reserve.
The economic justification provides for a comparison of costs associated with closing the DHW circuit:
- capital costs;
- property tax payments;
- operating costs of heat exchangers;
- payment for hot water supply.
The analysis showed that it is economically and technically feasible to close the DHW circuit. Savings are achieved by reducing payments for hot water supply when switching from an open to a closed scheme.
Costs for paying for hot water supply
The analysis showed that it is economically and technically feasible to close the DHW circuit. Savings are achieved by reducing payments for hot water supply when switching from an open to a closed scheme. The effectiveness of the investment project to close the hot water supply system is confirmed by the following indicators:
The effectiveness of the investment project to close the hot water supply system is confirmed by the following indicators:
- Savings in payment for hot water supply amount to 3,966.30 thousand rubles/year.
- The accumulated income is 38,726.53 thousand rubles/10 years.
- NPV (Net Present Value) – net present value is 24,569.93 thousand rubles.
- IRR (Internal Rate of Return) – the internal rate of return of the project is 456.1%.
- PI (Profitability Index) - profitability index is 28.62.
- PP (Payback Period) – the payback period for investments is 1.2 years.
- DPP (Discounted Payback Period) – discounted payback period of investments is 1.2 years.
After analyzing economic effect from closing the DHW system to specific example, we see that the payback of the project will be only 1.2 years. Of course, for each case the values economic indicators will be individual, but in general we can say with confidence that closing the hot water supply system using a plate heat exchanger significantly increases the energy efficiency of the housing and communal services system.
*Data based on the article “The level of depreciation of fixed assets in Russia is much higher than in other BRICS countries”, Russian newspaper: Economics - Modernization No. 5519 dated July 5, 2011
1. Formulation of the problem regarding the method (technology) under consideration for increasing energy efficiency; forecast of excessive consumption of energy resources, or description of other possible consequences nationwide while maintaining the current situation
In most cities of the Russian Federation today, hot water supply to consumers is carried out according to an open scheme.
The existence of such a scheme has the following disadvantages:
- increased heat consumption for heating and hot water supply;
- high specific consumption of fuel and electricity for heat production;
- increased costs of operating boiler houses and heating networks;
- high-quality heat supply to consumers is not provided due to large heat losses and the amount of damage to heating networks;
- increased costs for chemical water treatment.
2. Availability of methods, methods, technologies, etc. to solve the identified problem
It is necessary to transfer systems of transport and distribution of thermal energy to work according to a closed scheme with the construction of new and reconstruction of existing heating points in accordance with SP 41-101-95, reconstruction of heat consumption systems in houses.
3. Brief description the proposed method, its novelty and awareness of it, the availability of development programs; result with mass implementation nationwide
With a closed heating supply circuit, hot water is prepared at heating points, which receive purified cold water and coolant. In the heat exchanger, cold water, passing along the coolant tubes, is heated. Thus, there is no mixing of cold water into the coolant and hot water in such a system is heated cold water, going to the consumer. The spent coolant (its temperature drops at the outlet of the heat exchanger) is added to the new coolant and this “technical” the water is flowing for heating according to a dependent or independent scheme.
The transition to a closed connection scheme for hot water supply systems will ensure:
- reduction of heat consumption for heating and hot water supply due to the transfer to qualitative and quantitative regulation of coolant temperature in accordance with the temperature schedule;
- reduction of internal corrosion of pipelines (for the northern regions of the country) and salt deposits (for regions located to the south);
- reducing the wear rate of equipment at thermal power plants and boiler houses;
- radical improvement in the quality of heat supply to consumers, the disappearance of “overheating” during positive outdoor temperatures during the heating season;
- reduction in the volume of work on chemical water treatment of make-up water and, accordingly, costs;
- reducing the accident rate of heat supply systems.
4. Forecast of the effectiveness of the method in the future, taking into account:
- rising energy prices;
- growth in the well-being of the population;
- introduction of new environmental requirements;
- other factors.
As a final result, after abandoning the open hot water supply scheme and switching to a closed scheme, it will be possible to use the saved thermal power of stations and boiler houses to supply heat to newly connected consumers.
5. List of groups of subscribers and objects where this technology can be used c maximum efficiency; the need for additional research to expand the list
The maximum effectiveness of the implementation of this measure will be observed in cities with intensive development. The construction of new microdistricts, coupled with the organization of their heat supply according to a closed scheme, is most appropriate within the framework of the relevant city programs.
6. Outline the reasons why the proposed energy efficient technologies not used on a mass scale; outline an action plan to remove existing barriers
Currently, most of the heat supply systems in the capital (JSC Moscow United Energy Company and JSC Moscow Heating Network Company) operate precisely according to a closed scheme.
The situation is different in the regions. Since Soviet times, there has been a policy of limiting financial resources for the construction and maintenance of housing and communal services. Side factors of this policy were the creation of large centralized systems heat supply and the introduction of an open scheme in many cities.
7. The presence of technical and other restrictions on the use of the method at various sites; in the absence of information on possible limitations, they must be determined by testing
It is inappropriate to commission closed DHW schemes in cities with tap water, characterized by low salt content and high corrosive activity, requiring deaeration, as, for example, in St. Petersburg.
8. The need for R&D and additional testing; topics and goals of work
The need for R&D and additional testing when implementing this activity is not required
9. Existing measures of encouragement, coercion, incentives for the implementation of the proposed method and the need for their improvement
There are no existing measures to encourage and enforce the implementation of this method.
It is advisable to conduct energy surveys of existing heat supply systems to identify all negative consequences use of open schemes. The result of such examinations is technically sound conclusions and recommendations for transfer to a closed scheme.
10. The need to develop new or amend existing laws and regulations
Development required regulatory documentation on the implementation and operation of hot water supply systems using a closed scheme. It may be necessary to adopt compulsory legal acts on the transfer to a closed heat supply scheme, first of all, when supplying hot water to consumers under an open scheme that does not meet sanitary and epidemiological standards.
11. Availability of regulations, rules, instructions, standards, requirements, prohibitive measures and other documents regulating the use of this method and mandatory for execution; the need to make changes to them or the need to change the very principles of the formation of these documents; the presence of pre-existing normative documents, regulations and the need for their restoration
Currently, there are no regulatory documents regulating the use of this measure.
12. Availability of implemented pilot projects, analysis of their actual effectiveness, identified shortcomings and proposals for improving the technology, taking into account accumulated experience
The following can be mentioned as pilot projects being implemented to convert an open heat supply system to a closed one.
Specialists of OJSC VNIPIenergoprom have developed technical solutions for translation existing system heat supply of the city of Zelenograd on a closed circuit.
Within international program“Northern Dimension”, on the basis of GOUTP “TEKOS”, a project has been developed for the reconstruction of the heat supply system of the Leninsky district of Murmansk with a transfer to a closed heat supply scheme.
Specialists of OJSC Teploenergo have developed and are implementing a pilot project to transfer microdistrict No. 2 “Meshcherskoye Lake” to a closed hot water supply scheme as part of the corresponding investment program.
13. Possibility of influencing other processes with the mass introduction of this technology (changes in the environmental situation, possible influence on human health, increasing the reliability of energy supply, changing daily or seasonal load schedules energy equipment, changes in economic indicators of energy production and transmission, etc.)
When hot water supply to microdistricts is carried out according to an open scheme, consumers are often supplied from the heating system with water that has unsatisfactory organoleptic and bacteriological indicators. As part of the implementation of the event under consideration, the hot water supplied through a closed circuit will be of drinking quality and comply sanitary rules and standards.
The introduction of closed hot water supply schemes is an energy-saving measure. As a result of the implementation of this measure, not only the consumption of energy resources (electricity, heat and water) is reduced, but also emissions into the atmosphere are reduced and the reliability of the heat supply system is increased.
14. Availability and sufficiency of production capacity in Russia and other countries for the mass introduction of the method
The implementation of the event under consideration on a mass scale is problematic today, since it requires significant investment.
15. The need for special training of qualified personnel to operate the technology being introduced and develop production
The situation is aggravated by the shortage of qualified personnel due to the low level wages and the lack of specialized personnel training, which is urgently needed.
16.
Suggested implementation methods:
1) commercial financing (with cost recovery);
2) competition for implementation investment projects, developed as a result of work on energy planning for the development of a region, city, settlement;
3) budget financing for effective energy-saving projects with long payback periods;
4) introduction of bans and mandatory requirements on application, supervision of their compliance;
5) other offers.
To increase interest in the implementation of this type of measures, a consistent and methodical “turning point” in the psychology of customers, designers, installers and operating services is required, who still consider the most relevant implementation of outdated traditional schemes heating systems that do not require maintenance or adjustment.
It is also necessary to further create specialized organizations capable of taking on the entire chain of work from design and installation to commissioning and maintenance. modern systems heat supply. For this purpose, it is necessary to carry out targeted work on training specialists in the field of energy saving.
Only the combination of these measures will lead in the future to greater interest of city administrations in implementing energy-saving measures of this scale. Obviously, the most appropriate is the implementation of these measures within the framework of strategic projects for the development of heat sources and heating networks and city programs for the modernization of the housing and communal services complex with budgetary and commercial financing.
In order to add description energy saving technology to the Catalog, fill out the questionnaire and send it to marked “to Catalog”.
Specialists of the State Unitary Enterprise SO "Oblkommunenergo" warn their consumers about the upcoming dramatic changes in legislation regulating heat supply. UralPolit.Ru was informed about this by the press service of the enterprise today, December 4.
On January 1, 2013, amendments to federal law dated July 27, 2010 No. 190-FZ “On Heat Supply”. One of the most significant - addition of Article 29 with part 8:
8. From January 1, 2013, connection of objects capital construction consumers to centralized open heat supply systems (hot water supply) for the needs of hot water supply, carried out by selecting coolant for the needs of hot water
water supply is not allowed.
Besides this: addition of article 29 with part 9:
9. From January 1, 2022, the use of centralized open heat supply systems (hot water supply) for hot water needs
water supply carried out by withdrawing coolant for hot water supply is not allowed.
An open hot water supply scheme assumes that residents take hot water for their needs from the heating supply system, and a closed hot water supply system assumes the presence of special equipment for heating cold water and supplying it to residents of the house as hot water. The heat supply system operates autonomously in this case.
Open disassembly of hot water from the heating supply system has become a big problem and a headache for energy workers throughout Russia - today at least 70% residential buildings This is how hot water is supplied.
Experts warn that the task set is truly revolutionary, large-scale and brings with it many related problems that will also need to be solved, but this has not yet been outlined by the legislator.
We present expert opinion Deputy on this matter general director State Unitary Enterprise SO "Oblkommunenergo" Evgeniya Volkova:
In accordance with the amendments and additions made to Federal Law No. 190-FZ of July 27, 2010 “On Heat Supply” (introduced by Federal Law No. 417-FZ of December 7, 2011), approaches to the creation of hot water supply systems will radically change . If previously both systems – open and closed – had the right to exist, then from January 1, 2013, the connection of newly introduced capital construction projects to hot water supply systems will have to be carried out only according to a closed scheme. And from January 1, 2022, open heating systems should disappear as a species, or so, at least, the authors of the law believe. Let us briefly recall what the types of heat supply systems are. An open heating system is when the coolant is used for both heating and hot water supply. That is, hot water in heating devices and the tap in the kitchen, in the bathroom - the same thing. A closed heating system assumes that the coolant circulates in a closed loop, consuming thermal energy only for heating. In this case, hot water supply is carried out by heating cold water with the same coolant, but through a heat exchanger. Let's try to compare the pros and cons of both systems and understand the idea that is embedded in the new legislation.
With an open system, the entire coolant undergoes mandatory water treatment at the heat source - a boiler house or thermal power plant. Cold water, before becoming a coolant, usually requires a reduction in hardness in order to avoid the formation of scale when it is heated in boilers. In the absence of water treatment, hard water can destroy an entire boiler room in a matter of months. Therefore, at any heat source, great attention is paid to maintaining the water chemistry regime. Reagents are spent on water treatment ( table salt or sulfuric acid), electricity for water supply, routine maintenance of filters, funds are spent on routine operation and repair of equipment. With a closed circuit, all this will not happen, but who said that cold water does not need to be prepared for heating in the heat exchanger?
After all, if the water has increased hardness, then when it is heated in the heat exchanger, intensive formation of hard-to-remove scale will also occur. That is, the solution to the problem of water treatment during the transition from an open to a closed scheme will move from generating facilities to consumers. But this will no longer be a single enlarged complex, but many small installations that will also need to be maintained and incur costs for reagents and maintenance personnel. At the same time, it is appropriate to remember well-known rule– when dividing a single whole into several segments, the amount of costs increases. There is another factor - the level of maintenance of systems and equipment. It is impossible to compare the level of a plumber tightening nuts in residents’ apartments and complex system engineering support at large energy enterprises. It is unlikely that organizations serving internal systems buildings, will be able to ensure the proper level of operation of energy equipment (water treatment system, heat exchangers, automation for maintaining the required water parameters).
The disadvantage of an open circuit is the so-called overflow. This means that during relatively warm periods, when the outside air temperature is close to zero or above zero, the heat supply company is forced to maintain a minimum coolant temperature of at least 60 degrees, as required by SanPiN regarding the requirements for the quality of hot water. But heating systems do not require such temperatures during warm periods. For example, at zero degrees outside temperature The coolant temperature indicator is 52 degrees. At plus 5 outside, the coolant temperature should already be 45 degrees, and at plus eight – 41 degrees.
The literature on setting up heat supply systems mentions the so-called “cutting” temperature chart according to DHW conditions. That is minimum temperature The coolant temperature is assumed to be 60 degrees, and during warm periods of the heating season (usually September, October, April, May) consumers receive much more heating than would be required by the standard. It should be noted that the requirements for hot water temperature for closed systems are somewhat softer: the required minimum temperature is 55 degrees. As a result, fuel savings occur compared to an open system, however. this is a relative circumstance - many heat supply organizations, looking at the open vents in warm weather, and already actually withstand temperatures around 55-57 degrees.
A clear minus closed system– the need to replace water supply networks. Today, the wear and tear of these networks is quite high, and many areas have been rehabilitated over the past 5-6 years ( polyethylene pipes), i.e. their diameter has decreased. Water utilities are faced with the question: when switching to a closed system, it is necessary to increase throughput water supply networks almost doubled. Considering the above-mentioned circumstances, an impressive volume of pipelines will have to be replaced. But water tariffs are among the lowest and do not provide for the replacement of even the standard number of networks.
One of the options for a closed system is the supply of hot water from heat sources through a separate circuit (in Federal Law No. 190-FZ of July 27, 2010 “On Heat Supply”, oddly enough, only the concept of “open heat supply system” is formulated. There is nothing about a closed one said, however, in some technical regulatory documents the term “closed system” is explained precisely from the installation point of view heat exchangers from consumers. Therefore, whether the idea of the author of these lines will have the right to exist is still unclear). However, to solve this problem, it is necessary to install again or select from the existing ones a boiler on a heat source, which will heat water only for DHW needs. There is no need to “fence the garden” in the form of water treatment systems and heat exchangers for consumers, or to change water supply networks. But it arises new problem: Almost all heating networks will need to be redone to create dedicated hot water supply pipelines. For example, if now heating network consists of two pipes (supply and return), then with a separate circuit it is necessary to add two more pipes. In addition, it will be necessary to change the design of the network channels, since during their construction, as a rule, no one expects to increase the number of “threads” of pipelines, and where two pipes are already laid in the tray, two more obviously will not fit. In a word – a global replacement of all heating networks. By the way, why not? The problem of wear and tear on networks is known, thermal energy losses exceed all conceivable and unimaginable limits - very usefully, it will be possible to kill not two, but three or four birds with one stone. But the money for such modernization is unlikely to be found in the tariffs heat supply organizations. And even the standard percentage of networks replacement (4% per year) does not solve the problem within the prescribed period - until 2022. It takes at least 25 years, and then only under the most favorable circumstances and assistance from the state budget.
State Unitary Enterprise SO "Oblkommunenergo" is a backbone utility enterprise in the region that carries out a comprehensive modernization of housing and communal services Sverdlovsk region. Covering all areas of the utility business (power grid business, heat supply, sewerage and water supply), Oblkommunenergo systematically resolves issues of development of the energy complex and engineering infrastructure 40 municipalities Sverdlovsk region.
© Editorial office "UralPolit.Ru"
This is a system whose coolant is isolated and works exclusively for its intended purpose. It does not participate in water supply directly, but only indirectly, and is not taken from the network by consumers. Let's just say that the “transfer” of heat for heating systems and for hot supply passes through heat exchangers. For this purpose, heat exchangers (heaters), pumps of various specializations, mixers, control equipment, etc. are installed in heating stations of buildings.
The list may vary depending on the type and power of the item. Central and individual heating points can have varying degrees of automation; systems can be multi-stage and include several points on the way from the thermal power plant to consumers. Standardly, with a closed heat supply, the heat station has two circuits that ensure heat transfer to the heating system and water supply system. Each circuit is equipped with a heat exchanger of the appropriate type, plate, multi-pass, etc. is individually determined by the project.
The liquid or antifreeze that transfers heat from the heat treatment plant to secondary networks has a constant volume and can only be replenished by the feeding system in case of losses. The coolant of the main line must undergo water treatment to give it necessary properties, ensuring harmlessness for network pipelines and heat exchange, both heating points and heat treatment facilities.
Coolant efficiency
The cycle traversed by the heat carrier is slightly more complicated than in an open mechanism. The cooled coolant flows through the return line to district heating heaters or boiler rooms, where it takes on the temperature from the hot, process steam turbines, condensate or heated in a boiler. Losses, if any, are replenished with make-up liquid, thanks to the regulator. The device always maintains the set pressure, maintaining its static value. If heat is obtained from a thermal power plant, the coolant is heated by steam having a temperature of 120° - 140°C.
Temperature depends on pressure and sampling is usually done from medium pressure cylinders. Often there is only one heating extraction unit at the installation. The exhaust steam has a pressure of 0.12 - 0.25 MPa, which is increased (with controlled extraction) with seasonal cooling or steam consumption for aeration. When it gets colder, the liquid can be reheated by a peak boiler. The aerator can be connected to one of the turbine outlets, and chemically purified, prepared water enters the feed tank. The heat removed for consumers, obtained from steam condensates and steam, is regulated qualitatively, that is, with a constant volume of carrier, only the temperature is regulated.
Through the network pipeline, the coolant enters the heating station, where the heating circuits form the required temperature. The water supply circuit does this using a circulation line and a pump, receiving water heated by a heat exchanger and mixing it with the tap water and the water cooling in the pipes. The heating system has its own control valves, which allows it to qualitatively influence the heat selection. A closed system involves independent regulation heat selection.
However, such a scheme does not have sufficient flexibility and must have a productive pipeline. In order to reduce investments in the heating network, coupled regulation is organized, in which the water supply flow regulator determines the balance towards one of the circuits. As a result, the heating demand is compensated from the heating circuit.
The disadvantage of such balancing is that the temperature of the heated rooms varies somewhat. Standards allow temperature fluctuations within 1 – 1.5°C, which usually occurs while maximum flow for water will not exceed 0.6 calculated, for heating. As in an open heating system, it is possible to use a combined quality regulation heat supply. When the coolant flow and the heating networks themselves are calculated for the load of the heating and ventilation system, increasing the temperature of the medium to compensate for the need for hot supply. In such a case, the thermal inertia of buildings acts as heat accumulators, leveling out temperature fluctuations caused by uneven heat extraction from the connected system.
Advantages
Unfortunately, in the post-Soviet space, heat supply to the vast majority of consumers is still organized according to the old, open scheme. A closed scheme promises significant gains in many respects. That is why the transition to closed heating supply, on a national scale can bring serious economic benefits. For example, in Russia, at the state level, the transition to more economical option, became part of the energy saving program for the future.
Refusal old scheme will bring a reduction in heat loss due to the possibility of precise regulation of consumption. Each heating point has the ability to finely regulate heat consumption by subscribers.
Heating equipment operating in the isolated mode of a closed system is much less susceptible to the effects of introduced open network factors. The consequence of this is an extended life of boilers, heat treatment units and intermediate communications.
She doesn't demand increased stability To high blood pressure, along the entire length of heat-conducting lines, this significantly reduces the accident rate of pipelines due to pressure bursts. In turn, this reduces heat loss due to leaks. As a result, savings, stability and quality of heat and hot water, compensate for the shortcomings of the system. And they exist too. The procedures cannot be carried out centrally. Each individual closed loop requires its own maintenance. Be it turbines, subscriber circuits or an intermediate line.
Each heating point is a separate unit for water treatment. Most likely, when upgrading a circuit from open to closed, in most cases it will be necessary to increase the area required for the installation of ITP equipment, as well as reorganize the power supply. In addition, the consumption of cold water to supply the building increases significantly, since it is this that is used for heating in the heat exchangers and then to the consumer, with an independent connection of hot water. This will invariably entail the reconstruction of the water supply system in order to switch to a closed hot water circuit.
Global Introduction independent accession hot equipment to heating networks will entail a significant increase in the load on external cold water supply networks, since it will be necessary to supply consumers with the increased volumes required for hot water supply, which are now provided through heating networks. For many settlements this will become a serious obstacle to modernization. Additional equipment pumping units in hot supply and circulation plants, in building heating mechanisms will cause additional stress on electrical networks and we can’t do without their reconstruction either.