Set the compliance of the main types of thermal networks. Consumer attachment schemes for thermal networks

The prepared coolant (pairs of a certain pressure or water, heated to a predetermined temperature) is supplied by heat networks to heat consumers. The heat network consists of heat pipelines, i.e., connected by welding steel pipes, thermal insulation, shut-off and adjustment reinforcement, pump substations, automores, automatic extension, drainage and aircraft devices, mobile and stationary supports, maintenance cameras, and building structures.

Currently heating network They are carried out mostly by two-pipe, consisting of feed and reverse heat pipelines for water networks and steam vehicles with condensate pipes for steam networks.

The thermal network scheme is determined by the placement of heat sources (CHP or district boiler houses) in relation to the heat consumption area, the character of the heat load and the type of heat carrier. The network scheme should ensure reliability and efficiency of operation; The length of the network must be minimal, and the configuration is simple.

Couples as a coolant is mainly used for technological loads of industrial enterprises. The main load of steam networks is usually concentrated in a relatively small number of nodes, which are traces of industrial enterprises. Therefore, the specific length of steam networks per unit of calculated thermal load is usually small. When, by the nature of the technological process, short-term (up to 24 hours) breaks in the supply of steam, the most economical and at the same time sufficiently reliable solution is the laying of a single-tube steam pipeline with a condenser.

A more complex task is to choose the scheme of water thermal networks, since their load is usually less concentrated. Water thermal networks in modern cities serve big number consumers, measured often thousands and even tens of thousands of attached buildings.

Water thermal networks should be clearly divided into trunk and distribution.The trunk usually include heat pipelines connecting heat sources with heat consumption areas, as well as among themselves. The coolant comes from the trunk to the distribution networks and in distribution networks is supplied through group heat substations or local heat substations to the heat-consuming subscribers settings. The direct attachment of thermal consumers to the main networks should not be allowed, except in cases of accession of large industrial enterprises.

Distinguish radial and ring heating network. The most commonly applied radial networks, which are characterized by a gradual decrease in diameter as it removes from the heat supply source and reduce heat load (Fig. 26). Such networks are easy to use and require the smallest capital expenditures.

The disadvantage of radial networks is the lack of redundancy. When accidental at one of the highways, for example at the point but Mainstream I.will cease to supply heat to all consumers located after the point but In the course of the coolant. At the accident at the beginning of the highway, heating the heat supply of all consumers; attached to this highway. To reduce the supply of consumers, jumpers can be provided between highways. The jumpers are laid in the elevated diameter, they connect the middle or ends of the highways.

In the heat supply of large cities from several CHP, it is advisable to provide for mutual blocking of the CHP by connecting their mains by blocking bonds. In this case, a combined ring thermal network with several power sources can be created. The scheme of such a network is shown in Fig. 27. In such cases, thermal networks of CHP and large district or industrial boiler houses can be combined in some cases.

Ringing networks significantly increases the cost of networks, but increases the reliability of heat supply. The ringing of industrial thermal networks is sometimes mandatory in supplying the heat of consumers who do not allow interruptions in the supply of the coolant, as a rule, for technological needs. In this case, the ringing can be replaced by duplication, i.e. the gasket parallel to two steam lines or heat lines. The second steam pipe or heat pipeline in this case is in the hot reserve. With the relevant justifications in industrial enterprises, the backup power of thermal networks is provided for the subsequent expansion of the enterprise or individual workshops.

Combining the main thermal networks of several heat sources along with the redundancy of heat supply allows you to reduce the total boiler reserve for CHP and increase the degree of use of the most economical equipment in the system due to the optimal load distribution between heat sources.

To transport heat from the heat supply source to consumers, external heating network.They are among the most time-consuming and expensive elements of the heat supply system. Network consist of out steel pipesconnected by welding thermal insulation, shut-off reinforcement, compensators(thermal extension cords), drainageand aircraft devices movingand fixed supports.In the complex of building structures included cameras maintenanceand underground channel system.

Thermal networks are distinguished by the number of heat lines transmitting the coolant in one direction (single, two-, three- and four-pipe). One-tubethe highway is used to supply water without returning to boiler room or CHP and pair without condensate refund. Such a solution is possible when using water from the heat network on the target of hot water supply, technological needs or long heat supply from the CHP, as well as when using thermal waters.

In the heat supply of small settlements is used two-pipeopen heat supply system when the heat network consists of heat pipelines of the feed and reverse. Part of water circulating in open network, disassembled by subscribers for hot water supply.

In water and steam-tube closed systems, water circulating in thermal networks, or steam is used only as a coolant. The compound of the two-pipe heat supply system for the needs of heating and ventilation with a single-tube system of hot water supply leads to three-tube.If the hot water supply system has two pipes, the second pipe is auxiliary to create a circulation that eliminates the cooling of water with a small water treatment. Then the whole heat supply system together with a two-pipe heating system is called four-pipe.Three-tube or four-pipe can be applied in cases where it is rational to distinguish hot water to the third pipe. In the systems of hot water supply of residential buildings, hospitals, hotels, etc. It is desirable to provide for the circulation of water.

The thermal network scheme is determined by the placement of the CHP or the village boiler room among heat pipeliers. Networks are performed radialdeadlock.

For settlements of agricultural enterprises, improved by two- and three-storey buildings, located groups (Fig. 1), forming parallel buildings or closed contours, can be applied ring one-tubeheating network. Ring systems can be arranged

Fig. 1. Configuration of thermal networks: BUT -radial network; B.- radial network with jumpers; 1 - boiler room; 2 - thermal network; 3 - jumper

both from group boiler rooms and from a two-pipe highway with a heating boiler room.

Single-tube ring systems have the same general principles Actions as single-tube internal heating systems. The coolant in the network consistently passes each attached building and in the latter is approaching the temperature of the reverse water. The heat transfer regulation in heated buildings is achieved by installing devices with different heating surfaces.

Single-tube networks are parallel to the edge of the buildings of the attached. Distance from 3 to 5 m.from the building line. The number of attached buildings to the heat network is determined from the condition of non-test of permissible pressure for heating devices.

Thermal network pipelines are laid in disproving channelsand babeless(underground gasket), as well as on separate supports (ground gasket). The latter is applied in the territory of production sites, CHP or when passing through unresolved territories. Its use is limited by architectural considerations.

The main type of underground heat network laying is a gasket in non-voluntary channels.

In fig. 2 shows the design of the non-passing channel with concrete walls. With such a design, the main costs (50-58%) are on the construction part, thermal insulation of pipes, i.e., on the auxiliary facilities of the gasket. Channels are depicted at a depth of 0.7-1 m.from the surface of the Earth to the top of the slab overlap. In order to avoid drainage devices, the thermal network needs to strive to lay the level of groundwater. If this is not possible to avoid, it is used, the waterproofing of the channel of two layers of the rubberoid on the Klebemasse or the lowland gasket (up to 0.5 m).However, waterproofing channels of heat networks does not provide reliable protection They are from groundwater, as in practical conditions it is difficult to fulfill such insulation benign. Therefore, at present, when laying thermal networks below the level of groundwater is suitable for accompanying plastic drainage.

Drainage pipes with sand-gravel (rubbed) filter are paved along the channel, usually from the greatest inflow of groundwater. A sandy soil is laid under the canal and along the side of its walls, which contributes to the removal of groundwater. In some cases, drainage pipes

placed under the channel (Fig. 2), and the viewing wells are arranged inside compensatory niches. The drainage device under the channel costs significantly cheaper, especially in rock and floating soils, since in this case no additional broadening of trenches is required.

The use of porous concrete pipes should be cheaper and accelerates the drainage structure, as labor-intensive works on the filter device decrease.

When building a heating channel in fine-grained sandy and sandy soils, a sand-gravel or sand filter layer 150 may be arranged. mM.under the canal.

The heating of thermal pipelines is determined, as a rule, the Earth's profile, the marks of the inputs, the length of the network and the laying of other underground communications. The plumbing and gas pipeline are usually paved at the heat lifting level.

In the places of intersections, the device is allowed by the device of local fibers of the water supply system or gas pipeline with gasket them above or under the heat pipelines.

For a significant reduction in the cost of laying networks, a chamber-free gasket of pipes in thermal insulation shells are used. In this case, the thermal insulation of pipes is directly in contact with the soil. The material for the thermal insulation shell device should be hydrophobic, durable, cheap and neutral, relative to the metal of pipes. It is desirable that he possessed dielectric properties. To this end, the designs of the chapeless laying of pipes in piece goods made of cellular ceramics and in the shells of polycramics are mastered.

In places of branches of heating mains to consumers are arranged brick underground camera-wellswith shut-off and other reinforcement. The height of the chambers is taken at least 1.8 m. The entrance to the chamber is performed through a cast-iron hatch depth received 0.4-0.5 m.For cameras placed inside residential buildings, it is allowed to elevate them above the surface of the Earth to height not more than 400 mm.

To compensate for thermal extensions of pipelines from changing the temperature of the coolant on direct sections of the heating mains, flexible P-shaped compensatorsand on broken areas, the angles of rotation of the route (natural compensation) are used. Compensators are placed in special brick niches envisaged by the length of the heating main. The distance between compensators is set by the calculation or is accepted by nomograms depending on the temperature of the coolant.

Pipes in the canals are stacked on support concrete pillows.Moving pipes when changing their length ensures the locking of cameras from the surface of the Earth to the top of the coating.

The distance between the support pillows depends on the diameters of the stacked pipes. For pipes with a diameter of no more than 250 mM.distances are accepted 2-8 m.

Tasks of the hydraulic calculation of heat networks

Hydraulic calculation is one of the most important stages of design and operation of thermal networks.

When designing thermal networks, the direct task of hydraulic calculation includes:

1. Definition of pipeline diameters;

2. Determination of pressure loss in areas;

3. Determination of pressure at different points;

4. Link all the points of the system with static and dynamic modes.

In some cases (during the operation of thermal networks), the inverse problem may be solved, i.e. Definition bandwidth Pipelines with a known diameter or loss of pressure pressure.

As a result, after hydraulic calculation of the heat network, the following tasks can be solved:

1. Determination of capital investments;

2. Selection of circulating and mapping pumps;

3. Selection of subscriber connection schemes;

4. Selection of regulation of subscriber inputs;

5. Development of operation mode.

To carry out the hydraulic calculation, the diagram and profile of the thermal network must be set, the location of the source and consumers and the calculated thermal loads are indicated.

The thermal network scheme is determined by the placement of the heat source (CHP or boiler) relative to the heat consumption area, the characteristics of the heat load and the type of heat carrier ( fig. 5.1).

The basic principles that should be headed when choosing a heat network scheme is reliability and efficiency.

The economy of the thermal network is determined by the average specific pressure drop in length. \u003d. f.(network costs, electricity consumption on the pumping of the coolant, heat lines of pipelines, etc.)

Specific fusion pressure loss in hydraulic calculations of water heat networks should be determined on the basis of technical and economic calculations.

If technical and economic calculations are not conducted, it is recommended to accept:

Main pipelines;

Branch.

The reliability of the thermal network is the ability of the continuous supply of coolant to the consumer in the required quantity during the entire year. Requirements for the reliability of the thermal network increase with a decrease in the calculated temperature of the outer air and an increase in the diameters of pipelines. In lowering for various t. NR I. d. Tr are the need to reduce heat supply and allowable decrease in supply from the calculated value.

The emergency vulnerability of the heat network is particularly noticeable in large heat supply systems with the dependent accession of subscribers, therefore, when choosing a water thermal network scheme, special attention needs to be paid to the issues of reliability and redundancy of heat supply.

Water thermal networks are divided into highways and distribution. The highways include pipelines connecting a source with heat consumption areas. From highways, the coolant enters the distribution networks and on them through the CTP and the ITP to subscribers. The direct connection of consumers to the highways of the heat network should not be allowed, except for large industrial enterprises (with Q. > 4 MW.).

Fig. 5.1.

Principal

scheme thermal

SC - Sectionable Camera

In places of accession of distribution networks to the highways, partitioning chambers (SC) are built, in which: partitioning valves, distribution network valves, etc.

Sectionable valves are installed on highways from 100 mM. per 1000. m., 400 mM. at 1500. m.. Due to the separation of trunk networks on the section, the loss of water from the heat network during the accident is reduced, because The location of the accident is localized by sectional valves.

Fundamentally exist two schemes: dead-end (radial) and annular.

Fig. 5.2. Circuit diagrams of thermal networks: A, B - dead-end;

in - ring; 1 - Highway 1; 2 - Highway 2;

3 - reserving jumper

Tupique scheme (fig. 5.2A, B.) Cheaper at initial costs, requires less metal and easy to operate. However, less reliable, because When accidents, the highways stop the heat supply of subscribers attached beyond the crash site.

Ring scheme (fig. 5.2b) It is more reliable and applied in large heat supply systems from several sources.

To increase the reliability of deadlock, reserving jumpers are used ( fig. 5.2V.).

6.1 The choice of the heat supply system of the object is made on the basis of a heat supply scheme approved in the prescribed manner.

The heat supply scheme adopted in the project should provide:

safety and reliability of consumer heat supply;

energy efficiency of heat supply and thermal energy consumption;

the normative level of reliability, determined by three criteria: the probability of trouble-free operation, the readiness (quality) of heat supply and vitality;

ecology requirements;

safety of operation.

6.2 The functioning of thermal networks and SCR as a whole should not provide:

a) to a concentration exceeding the maximum permissible, during operation of toxic and harmful to the population, repair and operational personnel and the environment of substances in tunnels, channels, chambers, rooms and other structures, in the atmosphere, taking into account the ability of the atmosphere to self-cleaning in a particular residential quarter, microdistrict, settlement, etc.;

b) to a resistant violation of the natural (natural) thermal regime of plant cover (herbs, shrubs, trees), under which heat pipelines are laid.

6.3 Thermal networks, regardless of the method of gasket and heat supply system, should not pass through the territory of cemeteries, landfills, cattle boring, the disposal of radioactive waste, irrigation fields, filtering fields and other areas representing the risk of chemical, biological and radioactive contamination of the coolant.

The technological devices of industrial enterprises, from which harmful substances can flow into thermal networks should be added to thermal networks through a water heater with an additional intermediate circulation circulation between such a device and water heater when providing pressure in an intermediate circuit less than in a thermal network. At the same time, it should be provided for the installation of sampling points to control harmful impurities.

Consumer Hot Water Supply Systems should be connected via steam heaters.

6.4 Safe operation of thermal networks should be provided by developing measures in projects excluding:

the occurrence of stresses in the equipment and pipelines is higher than the maximum permissible;

the occurrence of displacements leading to the loss of stability of pipelines and equipment;

changes in the parameters of the coolant, leading to the failure (failure, accident) of pipelines of thermal networks and equipment of the heat supply source, thermal point or consumer;

unauthorized contact of people directly with hot water or with hot surfaces of pipelines (and equipment) at coolant temperatures of more than 55 ° C;

the flow of heat carrier in the heat supply systems with temperatures above the security standards;

reduced by refusal to refuse the air temperature in residential and industrial premises of consumers of the second and third categories below admissible values \u200b\u200b(4.2);

drain of network water in unforeseen places;

excess noise and vibration relative to CH 2.2.4 / 2.1.8.562 requirements;

the inconsistency of the parameters and criteria indicated in the section "Safety and Reliability of Heating" approved in the prescribed manner of the heat supply scheme.

6.5 The temperature on the surface of the heat-insulating structure of heat lines, fittings and equipment must correspond to the joint venture 61.13330 and should not exceed:

when laying heat lines in basements of buildings, technical undergrounds, tunnels and passing channels, 45 ° C;

with an overhead laying, in places available for service, 55 ° C.

6.6 The heat supply system (open, closed, including with separate hot water networks, mixed) is selected based on the heat supply scheme approved in the prescribed manner.

6.7 The direct water treatment of the network water in consumers in closed heat supply systems is not allowed.

6.8 In open heat supply systems, the connection of a part of the consumers of hot water supply through water heat exchangers on the thermal items of subscribers (according to the closed system) is allowed as temporary subject to ensuring (preserving) network water quality according to the requirements of existing regulatory documents.

6.9 When using atomic heat sources, heat supply systems should be designed to exclude the likelihood of radionuclides from the source itself into network water, pipelines, SCT equipment and consumer heat receiver.

6.10 As part of the SCC should include:

emergency Recovery Services (ABC), the number of personnel and the technical equipment of which should ensure complete reduction in heat supply when refusal on heat networks within the time specified in Table 2;

table 2

own repair and maintenance bases (RES) - for the areas of thermal networks with a volume of operation of 1000 conventional units and more. The number of personnel and technical equipment of the REC are determined taking into account the composition of the equipment used by the structures of heat lines, thermal insulation, etc.;

mechanical workshops - for sections (shops) of heat networks with less than 1000 conditional units;

unified repair and operational bases - for thermal networks, which are part of the divisions of thermal power plants, district boiler rooms or industrial enterprises.

Schemesheat networks

6.11 Water thermal networks should be designed, as a rule, two-pipe, filming at the same time heat for heating, ventilation, hot water supply and technological needs.

Multi-tube and single-tube main thermal networks are allowed to be used in a feasibility study.

Multi-tube distribution thermal networks should be laid after central thermal points if consumers have a centralized hot water supply system, as well as at various temperature graphs in heating, ventilation and technological consumers with independent accession.

Thermal networks transporting in open heat supply systems with network water in one direction, with an overhead gasket, it is allowed to be designed in a single-pipe version with a transit length of up to 5 km. With a larger length and absence of backstage sacking from other heat sources, thermal networks must be performed in two (or more) parallel heat pipelines.

Independent thermal networks to join technological consumers of heat should be provided if the quality and parameters of the coolant differ from the accepted in thermal networks.

6.12 The diagram and configuration of thermal networks should provide heat supply at the level of specified reliability indicators by:

applying the most progressive designs and technical solutions;

collaboration of several heat sources;

gaskets of backup thermal pipelines;

devices of jumpers between thermal networks of adjacent heat areas.

6.13 Thermal networks can be ring and dead-end, reserved and non-conductive.

The number and places of placement of backup pipelines between adjacent heat pipelines should be determined by the criterion of the probability of trouble-free operation.

6.14 Consumer heating systems can be connected to two-pipe water thermal networks on an independent and dependent scheme in accordance with the design task.

As a rule, according to an independent scheme, which provides for the installation in the thermal points of water heaters, it is allowed to attach, when justifying, the system of heating and ventilation of buildings in the 12th floors, and above, as well as other consumers, if such an attachment is due to the hydraulic mode of operation of the system.

6.15 Hot water coming to the consumer must meet the requirements of technical regulations, sanitary rules and regulations that determine its safety.

The quality of the feed and network water for open heat supply systems and the quality of hot water water in closed systems should meet the requirements for drinking water in accordance with SanPine 2.1.4.1074.

The use in closed heat supply systems of technical water is allowed in the presence of thermal deaeration with a temperature of at least 100 ° C (atmospheric pressure deaerators). For open heat supply systems, deaeration should also be made at a temperature of at least 100 ° C in accordance with SanPine 2.1.4.2496.

Other requirements for the quality of network and mapping water are shown in Appendix B.

6.16 Installation for feeding the heat supply system on heat source should ensure that the water of the appropriate quality and emergency feeding from the system of economic and drinking or production water supply systems should be supplied to the thermal network.

Consumption of feeding water in operating mode should compensate for the calculated (normalized) loss of network water in the heat supply system.

The estimated (normalized) loss of network water in the heat supply system includes the calculated technological losses (costs) of the power water and the loss of network water with a regulatory leakage from the heat network and heat consumption systems.

The average annual leakage of the coolant (m / h) from water heat networks should be no more than 0.25% of the average annual volume of water in the heat network and the attached heat supply systems, regardless of the attachment scheme (with the exception of hot water systems attached through water heaters). The seasonal leakage rate of the coolant is set within the average annual value.

Technological losses of the coolant include the amount of water to fill pipelines and heat consumption systems when they are planned and connecting new areas of the network and consumers, flushing, disinfection, carrying out regulatory tests of pipelines and equipment of thermal networks.

To compensate for these calculated technological losses (costs) of network water, additional productivity of water preparation installation and the corresponding equipment is needed (over 0.25% of the volume of the heating system), which depends on the intensity of the filling of pipelines. To avoid hydraulic shocks and better air removal from pipelines, the maximum wateral water flow () when filling the thermal network pipelines with a conditional diameter () should not exceed the values \u200b\u200bshown in Table 3. At the same time, the speed of filling the heat network should be linked to the performance of the feed source and It may be lower than the specified costs.

Table 3 - Maximum wateral water consumption when filling in thermal network pipelines

As a result, for closed heat supply systems, the maximum wateral water consumption (, m / h) is:

where - water consumption for filling the largest in the diameter of the partitioned section of the heat network, received according to Table 3, or below under the condition of such coordination;

Water volume in heat supply systems, m.

In the absence of data on the actual volumes of water, it is allowed to take it equal to 65 mW of the estimated heat load with a closed heat supply system, 70 mW 1 MW - open system and 30 mV 1 MW of the average load - for individual hot water networks.

In closed heat supply systems on heat sources with a capacity of 100 MW and more should be provided for the installation of reserve tanks of a chemically treated and deaerated substrate water with a capacity of 3% of the water volume in the heat supply system.

The inner surface of the tanks should be protected from corrosion, and water in them - from aeration, and the water update should be provided in the tanks.

The number of tanks regardless of the heat supply system is made at least two 50% of the working volume each.

6.17 For open heat supply systems, as well as in separate heat networks for hot water supply in order to align the daily chart of water consumption (PPU performance) on heat sources, tanks of chemically treated and deaerated substrate water via SanPiN 2.1.4.2496 should be provided.

The calculation capacity of batteries should be equal to a ten-hour average water consumption for hot water supply. The inner surface of the tanks should be protected from corrosion, and the water in them - from aeration, and the continuous renewal of water in the tanks should be provided.

When all tank batteries are located at the heat source, the maximum hourly consumption of feeding water (, m / h) supplied from the source is

where - the maximum water consumption for hot water supply, m / h.

6.18 At the location of the battery packs in the heat supply area, the consumption of feed water supplied from the heat source can be reduced to averaged value (, m / h) equal to the average

where is the coefficient determined by the project organization, depending on the volume of batteries, installed on the heat source and outside it;

Average estimated water consumption for hot water supply.

At the same time, the heat source should provide for tank-batteries with a capacity of at least 25% of the total compatibility of tanks.

6.19 Installing hot water batteries in residential neighborhoods is not allowed. The distance from hot water batteries to the border of residential neighborhoods should be at least 30 m. At the same time, on the soils of the 1st type of sedelion, the distance, in addition, there must be at least 1.5 thickness of the sedentary layer.

6.20 Batteries Batteries should be fenced with a common shaft with a height of at least 0.5 m. The cropping area must accommodate the working volume of water in the largest tank and have a removal of water to the drainage network or rain sewage system.

To improve the operational reliability of battery tanks, it is also necessary to provide a device for protection against avalanche-like destruction.

When placing battery tanks outside the territory of heat sources, their fencing should be provided with a height of at least 2.5 m to eliminate access of unauthorized persons to the tanks.

6.21 Hot water batteries in consumers should be provided for in hot water supply systems of industrial enterprises to align the removable water consumption schedule with objects that have concentrated short-term water supply costs for hot water supply.

For objects of industrial enterprises with the ratio of the average heat load for hot water supply to the maximum heat load on heating less than 0.2, the batteries are not installed.

6.22 For open and closed heat supply systems, an additional emergency feeding should be provided with chemically not treated and non-deaerated water, the consumption of which is taken in the amount of 2% of the average annual volume of water in the thermal network and the attached heat supply systems, regardless of the connection scheme (with the exception of hot water systems attached through Water heaters), unless otherwise provided by project (operational) decisions. If there are several separate thermal networks that leave the heat source manifold, the emergency feedback is allowed only for one largest thermal network. For open heat supply systems, an emergency feedback must be provided only from drinking water supply systems.

6.23 V From the heat transfer of any length from heat source to areas of heat consumption is allowed to use heat lines as heat-accumulating containers.

6.24 To reduce the loss of network water and, accordingly, heat for planned or forced emptying of thermal conductors is allowed to install in thermal networks of special tank drives, the capacity of which is determined by the volume of heat lines between the two partitioning valves.

Reliability

6.25 The ability of the projected and existing heat sources, heat networks and in general SCC to ensure the required modes, parameters and quality of heat supply (heating, ventilation, hot water, as well as the technological needs of enterprises in a pair and hot water) should be determined in three indicators (criteria): probabilities of trouble-free work, prepaid ratio, survivability [F].

The calculation of the system indicators, taking into account reliability, should be made for each consumer.

6.26 The minimum allowable indicators of the probability of trouble-free operation should be taken to:

heat source 0.97;

thermal networks 0.9;

consumer heat 0.99;

SCR as a whole 0.9x0.97x0.99 \u003d 0.86.

The customer has the right to establish higher indicators in the design of the design.

6.27 To ensure the reliability of thermal networks, determine:

the maximum permissible length of the non-conducted areas of heat lines (dead-end, radial, transit) to each consumer or thermal point;

places of placement of backup pipelines between radial heat pipelines;

the adequacy of the diameters of the new or reconstructed existing heat lines in the design of new or reconstructed existing heat pipes to ensure the backup feed supply to consumers with failures;

the need to replace on specific areas of heat networks and heat pipelines to more reliable, as well as the reasonableness of the transition to an overhead or tunnel gasket;

the order of repairs and replacement of thermal pipelines, partially or fully lost their resource;

the need for work on additional warming of buildings.

6.28 The readiness of the system to good work should be determined by the number of hours of readiness: the source of heat, thermal networks, consumers of heat, and also - the number of hours of uncountable outdoor air temperatures in this area.

6.29 The minimum allowable SCP readiness rate is received by 0.97.

6.30 To calculate the readiness indicator, determine (take into account):

the readiness of the SCB to the heating season;

the adequacy of the installed thermal power of the heat source to ensure the proper functioning of the SCR with uncourled cooling;

the ability of heat networks to ensure a good operation of the SCR with uncourled cooling;

organizational and technical measures necessary to ensure the proper functioning of the SCT at the level of a given readiness;

the maximum permissible number of hours of readiness for heat source;

the temperature of the outer air at which the specified inner air temperature is ensured.

Reservation

6.31 The following redundancy methods should be provided:

organization of collaboration of multiple heat sources on unified system transportation of heat;

reservation of thermal networks of adjacent areas;

device of backup pumping and pipelines;

installation of battery tanks.

With underground gasket of thermal networks in non-voluntary channels and chapeless gasket, the heat feed value (%) to ensure the internal air temperature in heated rooms is not lower than 12 ° C during the repair period after the failure should be taken according to Table 4.

Table 4.

Diameter of pipes of thermal networks, mm	Calculated outdoor air temperature for heating design, ° C
	Allowable reduction in heat supply,%, to

6.32 Sections of the above-ground gasket with a length of up to 5 km are allowed not to reserve, except for pipelines with a diameter of more than 1200 mm in areas with calculated air temperatures for the design of heating down minus 40 ° C.

Reservation of heat supply for thermal networks laid in tunnels and passage channels is allowed not to provide.

6.33 For consumers of the first category, it is allowed to provide local reserve sources of heat (stationary or mobile) in the absence of a reservation possibility from several independent heat sources or thermal networks.

6.34 To reduce the heat supply of industrial enterprises, it is allowed to provide local sources of heat.

Vitality

6.35 The minimum supply of heat for heat-driven, located in unheated rooms and outside, in the entrances, staircases, in attics, etc., should be sufficient to maintain the water temperature during the entire repair period after the failure of no lower than 3 ° C.

6.36 In projects, measures should be developed to ensure the vitality of elements of heat supply systems, which are in areas of possible effects of negative temperatures, including:

organization of local circulation of network water in thermal networks before and after an accident;

shutting of network water from heat use systems in consumers, distribution thermal networks, transit and main thermal conductors;

warming up and filling in thermal networks and heat use systems of consumers during and after the end of repair and restoration work;

checking the strength of the elements of thermal networks on the adequacy of the stock of equipment and compensating devices;

ensuring the necessary harruses of non-safe heat-conducting under possible floodings;

temporary use, with the possibility, mobile heat sources.

Collectionand refund condensate

6.37 Condensate collection and refund systems The heat source should be provided closed, while overpressure in the condensate prefabricated tanks should be at least 0.005 MPa.

Open systems for collecting and returning condensate is allowed to provide for the amount of returned condensate less than 10 t / h and the distance to the heat source up to 0.5 km.

6.38 Return of condensate from the condensate trap on the total network is allowed to be used when the pair pressure difference is not more than 0.3 MPa under condensate trap.

When returning condensate with pumps, the number of pumps submitting condensate in general Networkis not limited.

The parallel operation of pumps and condensate traps, discharged condensate from steam consumers on a common condensate network, is not allowed.

6.39 Pressure condensate pipelines should be calculated at the maximum time consumption of condensate, based on the operating conditions of the pipelines with a complete cross section with all the condensate return modes and protection of them from emptying during condensate feed. The pressure in the network of condensate pipelines with all modes should be excessive.

Condensate pipes from condensate trades to prefabricated condensate tanks should be calculated based on the formation of a steam mixture.

6.40 The specific loss of friction pressure in condensate pipes after pumps should be taken not more than 100 P / m with an equivalent roughness of the inner surface of the condense pipes 0.001 m.

6.41 The capacity of the condensate tanks installed in thermal networks, at the heat points of consumers should be taken at least a 10-minute maximum condensate consumption. The number of tanks in year-round work should be taken at least two, with a capacity of 50% each. With seasonal work and less than 3 months a year, as well as at the maximum condensate consumption, up to 5 t / h is allowed to install one tank.

When monitoring the quality of condensate, the number of tanks should be taken, as a rule, at least three with a capacity of each providing the time to analyze condensate on all necessary indicators, but not less than a 30-minute maximum condensate intake.

6.42 Feed (performance) pumps for pumping condensate should be determined at the maximum time consumption of condensate.

The pump pressure must be determined by the magnitude of the pressure loss in the condensate pipeline, taking into account the height of the condensate lifting from the pump to the precast tank and the amount of overpressure in the prefabricated tanks.

Pumps submitted condensate into a common network should be determined with the conditions for their parallel work with all condensate refund modes.

The number of pumps in each pump should be taken at least two, one of which is backup.

6.43 Permanent and emergency discharges of condensate in a rain or domestic sewage system are allowed after cooling it to a temperature of 40 ° C. When resetting the production sewage system with constant runoff, condensate is allowed not to cool.

6.44 Returning from consumers to the source of heat Condensate must meet the requirements of the maintenance rules of electrical stations and networks.

The temperature of the returned condensate for open and closed systems is not normalized.

6.45 In the collection and return of condensate, it should be provided to use its warmth for the own needs of the enterprise.

The adopted scheme of thermal networks largely determines the reliability of heat supply, the maneuverability of the system, the convenience of its operation and economic efficiency. The principles of building large heat supply systems from several heat sources, medium and minor systems differ significantly.

Large and medium systems should have a hierarchical construction. The highest level is the main networks connecting heat sources with large thermal nodes - district thermal points (RTP), which distribute the coolant over low-level networks and provide autonomous hydraulic and temperature modes in them. The need to strictly dismember the thermal networks on the highway and distribution networks are noted in a number of works. The lower hierarchical level is distributed networks that transport heat carrier in group or individual heat points.

The distribution networks are attached to the main in the RTP through waterproof heaters or directly with the installation of mixing circulation pumps. In the case of joining the water heaters, the hydraulic modes of the main and distribution networks are completely divided, which makes a system of reliable, flexible and maneuverable. Strict requirements for pressure levels in trunk heat pipes, put forward by consumers, are removed here. Only the requirements of the insights of the pressure, determined by the strength of the heat network elements, inquiring the coolant in the supply pipeline and ensuring the necessary disposable pressure in front of the water heaters. The network of the highest hierarchical level, the coolant can be supplied from various sources with different temperatures, but provided that they exceed the temperature in distribution networks. Parallel operation of all heat sources on the combined main network It makes it possible to best distribute the load between them in order to save fuel, provides sources redundant and reduce their total power. The flaked network increases the reliability of heat supply and ensures the supply of heat to consumers with the failures of its individual elements. The presence of multiple power supply sources reduces the required reserve of its bandwidth.

In the heat supply system with pumps in the RTP, there is no complete hydraulic insulation of trunk networks from distribution. For large systems with extended slotted trunk heat pipelines "and several power sources, the method of controlling the hydraulic mode. Networks, subject to restrictions in pressures for consumers, can be solved only when equipping RTP with modern automation. These systems also allow maintenance of independent circulation regime of the coolant in distribution networks and The temperature regime other than the temperature regime in the highways. As a result of the installation of pressure regulators on the feed and reverse lines, it is possible to provide a reduced pressure level.

In fig. 6.1 shows a single-cinema scheme of a large heat supply system, which has two hierarchical levels of thermal networks. The highest level of the system is represented by a ring main network with branches to RTP. From the RTP goes the distribution networks to which consumers are connected. These networks constitute the lowest level. The main network of consumers do not join. The coolant in the trunk network comes from two CHP. The system has a reserve source of heat - the district boiler room (RK). The scheme can be performed with one type of connecting network connection to the RTP (Fig. 6.1.6 or B) or combined with two species.

Systems with two hierarchical levels reserve only the highest level. The reliability of heat supply is provided by the choice of such power of the RTP, in which the reliability of a non-conductive (impressive) network turns out to be sufficient. The adopted reliability level determines the length and maximum distribution network diameters from each RTP. Summit reserves and heat sources, and heat pipelines. Reservations are carried out by connecting feed and return highways with appropriate jumpers. There are two types of jumpers (see Fig. 6.1). Some of them reserve the network, "providing its reliable operation when refusing to heat pipelines, valves or other networks. Others reserve the sources of heat, providing a coolant flow from the zone of one source into the zone of the other when it fails or repair. Heat higgling together with jumpers form a single annular network. . The diameters of all heat lines of this network, including the diameters of the jumpers, should be calculated on the skipping of the required amount of coolant in the most unfavorable emergency situations. In normal mode, the coolant moves along all the heating boards of the system and the concept of ringing "jumper" loses its meaning, especially since variables of hydraulic The flow point modes can be moved, and the role of "jumpers" will perform various sections of the network. Since the backup elements of the thermal network are always in operation, such a reservation is called loaded.

Systems with a loaded reserve have the operational disadvantage, which consists in the fact that when an accident occurs to detect the highway on which it occurred, presents great difficulties, because all highways are combined into a common network.

Preserving the principle of hierarchical construction of the heat supply system, you can apply another backup method using it using
Unloaded reserve. In this case, the jumpers that ensure the redundancy of heat sources, in normal mode are disabled and do not work. It should be noted here that since the basis of the principle of constructing the system scheme is based hierarchy and the highest and lower level are divided by large thermal nodes, consumers do not attach consumers, regardless of whether they are loaded or unloaded reserve. Each CHP provides heat supply of its zone. In situations where the need to reserve one source to other, reserve jumpers are turned on.

When using the principle of unloaded redundancy, the ringing of networks to ensure the reliability of heat supply at the failures of the elements of the heating network can be carried out by single-tube jumpers, as suggested in the MISI. V. V. Kuibyshev. In places of connecting jumpers to heat pipelines, nodes are located, allowing to switch jumpers for feed or reverse LNA depending on which an accident occurred from them (the probability of simultaneous failure of two elements is negligible).

The use of single-tube jumpers makes it possible to significantly reduce additional capital investments in reservation. Under normal mode, the network works as a dead end, i.e. each highway has a specific circle of consumers and independent hydraulic mode. In case of emergency situations, the necessary backups are included. Beams. With unloaded redundancy, as well as under loaded, the diameters of all heat lines, including jumpers, are calculated on the skipping of the required amount of coolant with the most stressful hydraulic modes in emergency situations. The schematic diagram is preserved and can be illustrated in Fig. 6.1. The difference from the diagram with loaded reservation is that jumpers 3 are performed by one-tube. Operation of the system is carried out with closed valves on all jumpers 3 and 4. Such a mode of operation is more convenient, since with independent hydraulic modes of highways easier to control their condition. In addition, the use of an unloaded reserve - single-tube jumpers-gives a significant economic effect.

To ensure reliable and high-quality heat supply, the hierarchical construction of the scheme and reservation is still not enough. It is necessary to ensure the controllability of the system. You should distinguish between two types of system management. The first form ensures the effectiveness of heat supply during normal operation, the second view allows the limited heat supply of consumers with emergency hydraulic modes.

Under the controllability of the system in the process of operation, the property of the system understands, which allows changing the hydraulic and temperature modes in accordance with the changing conditions. For the possibility of controlling hydraulic and temperature modes, the system must have thermal items equipped with automation and devices. Allowing autonomous circulation modes in distribution networks. In the best degree of manageability, systems with hierarchical construction and RTP are answered. The RTP C, the pumping connection of the distribution networks to equip pressure regulators that support constant pressure in the reverse line and the constant pressure drop between the feed and return lines after the RTP. Circulation pumps allow to maintain the disposable pressure drop after RTP constant with a reduced water flow in the external network, as well as reduce the temperature in networks for RTP by mixing water from the reverse line. The RTP is equipped with automation that allows you to cut off them from the main thermal pipelines during accidents in distribution networks. RTP attach to highways from two sides of the sectional valve. It provides the power of the RTP with an accident at one of the plots. The partitioning valves on the highways set by about 1 km. If RTP attach from two sides of each gate, then for highways with an initial diameter of 1200 mm, the RTP load will be approximately 46,000 kW (40 Gcal / h). In the new planning solutions of cities, the main urban-planning element is the microdistrict with a heat load of 11,000-35,000 kW (10-30 Gcal / h). It is advisable to create large RTP at the calculation of the heat supply of one or several neighborhoods. In this case, the thermal load of the RTP will be 35,000-70,000 kW (30-60 Gcal / h):

Another way to attach distribution networks to the mains - C-CH ^ The heat exchangers located in the RTP does not require the equipment of the RTP large number automatic devicesSince hydraulically trunk and distribution networks are separated. This method is particularly advisable to apply with complex terrain and presence of zones with reduced geodesic marks. The choice of method should be carried out on the basis of a technical and economic calculation.

The task of managing the emergency hydraulic mode occurs when calculating heat lines to skip the limited amount of heat carrier during accidents.

Considering the relatively small duration of emergency situations on thermal networks and a significant heat accumulating ability of buildings, to the MISI. V. V. Kuibyshev developed the principle of substantiation of the reserve of the capacity of thermal networks based on the limited (reduced) heat supply of consumers during emergency repairs on networks. This principle can significantly reduce additional capital investments - to reservation. For the practical implementation of limited heat supply, the system must be controlled when switching to emergency hydraulic mode. In other words, consumers must select the specified (limited) amount of coolant from the network. To do this, it is advisable at each input in the thermal node on the bypass to install the regulator - the flow limiter. When the emergency mode occurs, the supply of coolant consumers switches to the bypass. Blocks of such regulators should be installed on the entry in the RTP. If the RTP is equipped with flow regulators to allow remote control, then they can perform the role of regulators - expense limiters.

If the emergency hydraulic mode is not controlled, then the reserve of network bandwidth must be calculated for 100% coolant consumption during accidents, which will lead to unfounded metal overrun.

The practical implementation of the management of operational and emergency regimes is possible only in the presence of telemechanization. Telemechanization should ensure control of parameters, signaling about the status of equipment, pump control and valves, regulation of network water flow.

Above the optimal schemes of modern large heat supply systems were considered. Small heat supply systems with a load, approximately appropriate loads of RTP, design
unwiered. Networks are performed by dead-end branched. With the increase in the power of the heat source, there is a need to reserve the head part of the thermal network.

Controlled systems with hierarchical construction are modern progressive systems. However, heat networks under construction under construction and most of the exploited are referred to so-called dischanted networks. With this solution to all consumers of heat (and large, and small), in parallel attach to the network, and to the highways, and to the distribution heat carrier. As a result of this method of accession, essentially, the difference between trunk and distribution networks is lost. They represent unified Network With a single hydraulic mode, only the value of the diameter differs. Such a system has no hierarchical construction, is uncontrollable and for its redundancy in order to increase reliability, the heat of supply is needed significant capital investments. From the above, we can conclude that the newly under construction systems of heat supply should be designed manageable with hierarchical construction. During the reconstruction and development of existing systems, it is also necessary to design a RTP and ensure a clear separation of the secrets to the main and distribution.

The existing thermal networks in their construction can be divided into two types: radial and ring (Fig. 6.2). Radial networks are dead-end, non-conductive and therefore they do not provide the necessary reliability. Such networks can be applied to small systems if the heat source is located in the center of heat supplying the area.