RU2364794C1 - Centralised heat supply system and method - Google Patents

Abstract

FIELD: heating system. ^ SUBSTANCE: invention refers to centralised heat supply systems and methods involving thermal pump plants. Centralised heat supply system consists of steam boiler with furnace chamber and gas ducts wherein there located are steam heating surfaces connected via steam turbine or in a direct manner to system water heaters, direct and return system water circuit, heating system circuit with thermal pump plant arranged at thermal point. The condenser outlet of thermal pump plant is connected to final heat transfer stage of the heating system circuit, and the evaporator outlet of which is connected to the return cooled system water returned to the system heaters to be heated. Return cooled system water circuit is equipped with at least one well for accumulating excess cooled system water under the ground, and for pre-heating cooled system water with exit gas heat by using evaporation heat there additionally installed in the boiler gas duct is the system economiser, as well as for accumulating the system water heated in the system economiser during inter-heating period and/or heated in system heaters, the direct system water circuit is equipped with at least one heat-insulated pond. Centralised heat supply method is described as well. ^ EFFECT: increasing utilisation degree of fuel energy for heating heat carrier based on the complex technology involving intensive heat utilisation of exit gases by using evaporation heat, additional removal of emissions from them, increasing degree of heat transfer to consumer. ^ 15 cl, 1 ex, 1 dwg

Description

The invention relates to a power system, in particular to systems and methods for district heating, using heat pump units.

A well-known district heating system, consisting of a cogeneration power plant, including a main steam power circuit, a cooling water circuit, a primary network water circuit with hot water and heating water heaters, and a heating system circuit with an elevator and a heat pump installation located at heating stations and connected via a return network water path the primary circuit to the input / output of the evaporator, and along the return path of the heating system to the input / output of the condenser [patent RU 2095581, publ. 11/10/1997]. A disadvantage of the known heating system is the low degree of use of fuel energy for heating the coolant and the lack of deep heat recovery of the flue gases, therefore, the temperature of the cooled return network water entering the turbine condenser and leaving it does not exceed an average of 20 ° C and for heating it to standard temperature, the average value of which when leaving the heating devices in the return water pipeline should be 70 ° C, additional installation of a network heater and additional additional steam extraction from the turbine, which reduces the amount of generated electricity and the absolute efficiency of the system.

A method of district heating is also known, according to which the network water is heated in the network heaters of the heating power plants, hot water is supplied through the supply main pipe to the heating systems, the return network water is cooled and the heating system water is re-heated using the cascade heat pump installation located at the heating station, it is returned chilled water through the return main pipeline to the network heaters and heated due to the heat of condensation worked in the steam turbine [patent RU 2266479, publ. December 20, 2005]. The disadvantage of this method is the low degree of use of fuel energy for heating the coolant, the lack of a comprehensive technology for the utilization of heat of the exhaust gases, purification of combustion products, accumulation and storage of heat.

As a prototype adopted a system and method of district heating, which used the technical principle of a heat pump and related equipment [patent CN 1587825A, publ. 09/23/2004]. The district heating system contains a steam boiler with a combustion chamber and flues, in which there are steam heating surfaces that are closed to the network water heaters, the network water circuit, the heating system circuit with a heat pump installation located at a heating station, the condenser output of which is connected to the final heat transfer stage of the circuit heating system, and the evaporator outlet is connected to the circuit of the chilled network water returned to the system. According to the centralized heat supply method, fuel is burned in the boiler’s combustion chamber, steam is generated in the heating surfaces located in the boiler’s combustion chamber and gas ducts, which is used to generate thermal energy, for which heating water is heated in the network water heaters and supplied to the system circuit heating; the main heat transfer stage that has passed in the heating system circuit is cooled in the heat pump evaporator, and the heat taken from the return mains water is used to heat the water that is supplied to the heating circuit to pass the final heat transfer stage, and the cooled return main water is returned into the network water circuit. A disadvantage of the known system and method is the low degree of use of fuel energy and the lack of deep heat recovery of flue gases, environmental pollution by harmful emissions, as well as the low level of heat transfer to the consumer and the lack of means of accumulation and storage of coolant, the seasonality of its consumption.

The technical problem for which this device is proposed is to increase the degree of use of fuel energy for heating the coolant based on a comprehensive technology that includes deep, using the heat of vaporization, utilization of the heat of the exhaust gases, their additional purification from harmful emissions, increasing the level of heat transfer to the consumer , accumulation and preservation of low-temperature coolant, as well as accumulation and preservation of high-temperature coolant in the interheating period, elimination of the seasonal cyclicality of its consumption.

This technical problem is solved by the proposed district heating system, comprising a steam boiler with a combustion chamber and flues, in which there are steam heating surfaces that are closed through a steam turbine or directly to network heaters, a direct and reverse network water circuit, a heating system circuit with a heat pump installation located at a heat point, the condenser output of which is connected to the final heat transfer stage of the heating system circuit, and the evaporator output of which is connected to the circuit return chilled network water returned for heating to network heaters. What is new is that the return chilled network water circuit is equipped with at least one well for accumulating excess chilled network water in the soil stratum, and for pre-heating the chilled network water with the heat of the exhaust gases, using the heat of vaporization, a network economizer is additionally installed in the boiler flue, and also, for accumulation during the inter-heating period, heated in the network economizer and / or heated in network heaters of network water, the direct network water circuit is equipped with at least one insulated reservoir. An additional network economizer can be installed in the gas duct of the boiler outside the combustion chamber. Consumer heat supply will be more efficient if the heating system circuit is equipped with at least three heat transfer stages. The first stage of heat transfer can be performed according to the traditional scheme. The consumer will be fully provided with heat if the second heat transfer stage is performed with a changed high-speed regime of water movement in the pipeline, and / or an increased heat transfer surface and / or a changed type of heating devices. The third heat transfer stage can be performed using water heated in the condenser of the heat pump installation with return network water, which has passed the first and second heat transfer stages, as well as with a changed high-speed mode of water movement in the pipeline and / or an increased heat transfer surface and / or a changed type of heating devices. The operating mode will be observed optimally if the heat and power equipment, well, reservoir and pipelines are equipped with appropriate pumps, shut-off and control valves. A method of district heating is proposed, according to which fuel is burned in the boiler’s combustion chamber, steam is obtained in the heating surfaces located in the boiler’s combustion chamber and gas ducts, which is used to generate electric and / or thermal energy, and to produce the latter in network heaters, direct steam is heated network water and feed it into the circuit of the heating system, where the net water that has passed the initial stages of heat transfer in the circuit of the heating system is cooled in the heat pump evaporator, and with heat, taken from the return network water, the water is heated in the condenser of the heat pump, which is supplied to the heating system circuit to pass the final stage of heat transfer, while the return cooled network water is returned for heating to the network heaters. What is new is that excess reverse chilled network water is accumulated in at least one well in the soil stratum, and when consumed, the cooled network water is preheated with the heat of the exhaust gases, using the heat of vaporization, in a network economizer additionally installed in the boiler duct, after which heated in the network economizer and / or heated in the network heaters, the network water is supplied to the circuit of the heating system, and during the inter-heating period accumulated in at least one heat lirovannoy reservoir of direct water contour. The consumer will be fully supplied with heat if the network water heated in the network economizer and / or heated in the network heaters is supplied to the heating circuit, where it will pass three stages of heat transfer. At the first stage, heat transfer can be carried out according to the traditional scheme. The consumer will be provided with sufficient heat if at the second stage the heat transfer will be carried out by changing the speed regime of water movement in the pipeline and / or increasing the heat transfer surface and / or changing the type of heating devices. At the third stage, heat transfer can be carried out with water, heated in the condenser of the heat pump installation with network water that has passed the first and second stages of heat transfer in the heating system circuit, as well as by changing the speed of water in the pipeline and / or increasing the heat transfer surface and / or changing the type of heating appliances. To equalize the parameters, it is better if, before accumulating in a thermally insulated reservoir, the temperature of the network water heated in the network heaters will be reduced to the temperature of the network water heated in the network economizer. The temperature of the network water heated in the network heaters can be lowered by mixing with reverse chilled network water. The system will function optimally if the operating mode of the power equipment, the well and the heat-insulated reservoir, as well as the direction and speed of the water in the pipelines will be regulated by appropriate pumps, shut-off and control valves.

The invention is illustrated in graphic materials. The drawing shows a schematic diagram of district heating from a solid fuel fired power plant with a heat pump installation at a heating point in the heating circuit, as well as a well for accumulating reverse chilled network water in the soil stratum, and a thermally insulated reservoir for accumulating heated network water in the territories adjacent to the CHP.

The proposed district heating system includes a steam boiler 1 with a combustion chamber and flues. In the upper part of the combustion chamber and at the inlet of the gas duct of the boiler 1, there are heating surfaces in the form of a superheater 2, which is closed to the steam turbine 3. In the downstream part of the gas duct of the boiler 1, between the electrostatic precipitator 4 and the smoke exhauster 5, there is an additional network economizer 6 designed for preheating the reverse cooled network water with the heat of the exhaust gases, using the heat of vaporization. The turbine 3 contains a high-pressure cylinder 7, a medium-pressure cylinder 8, a low-pressure cylinder 9 and is mechanically connected to an electric current generator 10. The low-pressure cylinder 9 is closed to the condenser 11 and to the main network water heater 12, which is part of the direct network water circuit. The high-pressure cylinder 7 is closed to a peak network water heater 13, also included in the direct network water circuit. The heating system circuit contains three stages of heat transfer, where the first stage 14 contains a traditional heating circuit, the second stage of heat transfer 15 contains a modernized heating circuit with an increased (up to 30%) high-speed mode of water movement in the pipeline and / or increased (30%) heat transfer surface of the heating appliances and / or a modified type of heaters, and the third heat transfer stage 16 also contains an upgraded heating circuit with a coolant heated in the condenser of the heat pump installation 17 reverse network water that has passed the first 14 and second 15 stages of heat transfer in the circuit of the heating system, as well as with an increased (up to 30%) high-speed mode of movement of water in the pipeline and / or increased heat transfer surface of the heating devices (up to 30%) and / or a changed type of heating appliances. The evaporator outlet of the heat pump installation 17 is connected to a return chilled network water circuit, which is equipped with a well 18 for accumulating excess reverse cooled network water in the soil stratum. To accumulate during the inter-heating period heated in the network economizer 6 and / or heated in the network water heaters 12 and 13, the direct network water circuit is equipped with a heat-insulated water reservoir 19. All heat power equipment, including well 18, water reservoir 19 and pipelines, are equipped with appropriate pumps, shut-off and control valves.

According to the proposed method of district heating from the CHP in the furnace chamber of boiler 1, solid fuel is burned, in the heating surfaces made in the form of a superheater 2 installed in the upper part of the furnace chamber and at the inlet of the boiler duct 1 and washed by hot gases, steam is produced which is fed to the heating a turbine 3 having a cylinder of high 7, medium 8, low 9 pressure, mechanically connected to an electric current generator 10. The exhaust steam from the low pressure cylinder 9 is dumped into the condenser 11, about laden with circulating water, from where the condensate together with the feed water is returned to the boiler 1. The controlled extraction of steam from the turbine 3 into the network water heaters 12 and 13 is carried out in two stages: at the first stage, steam from the low pressure cylinders 9 is fed to the main network water heater 12, where the network water is heated to a temperature of 110 ° C, and in the second stage, steam from the high-pressure cylinder 7 is fed to a peak network water heater 13, where the network water is heated to a temperature of 150 ° C. Heated direct network water is supplied to the heating circuit, where after passing through the first heat transfer stage 14, the water temperature is lowered from 150 ° C to 70 ° C, after passing the second heat transfer stage 15, the temperature of the network water is lowered from 70 ° C to 45 ° C. After the 14th and 15th stages of heat transfer in the heating system circuit, the return network water at a temperature of 45 ° C is cooled in the evaporator of the heat pump 17 to a temperature of 5 ° C, and the heat taken from the return network water in the condenser of the heat pump 17 is heated to a temperature of 70 ° C, which is supplied to the heating system circuit to pass the final third heat transfer stage 16, after which the water temperature is lowered from 70 ° C to 45 ° C, and the return network water cooled to 5 ° C in the evaporator of the heat pump installation is returned to I reheat in the network heaters 12 and 13. The excess reverse chilled network water is accumulated in the well 18 in the thickness of the soil, and if necessary, it is preheated to a temperature of 95 ° C with the heat of the exhaust gases using the heat of vaporization in the network economizer 6 installed in the boiler flue 1, after which it is preheated in the network economizer 6, and then heated to a temperature of 150 ° C in the network heaters 12 and 13, the network water is supplied to the circuit of the heating system. Heated network water is also accumulated in a heat-insulated reservoir 19 of the direct network water circuit for use in the inter-heating period. Before accumulating in a heat-insulated reservoir 19, the temperature of the network water heated in the network heaters is lowered to the temperature of the network water heated in the network economizer by mixing with reverse cooled network water. The operating mode of the heat power equipment, the well 18 and the heat-insulated reservoir 19, as well as the direction and speed of the water in the pipelines are regulated by pumps, shut-off and control valves.

Deep comprehensive heat recovery will allow, depending on the type of fuel, to increase the degree of fuel energy use by 8-22%, and heat storage, depending on the region and type of electric power station, can further increase it by 37-61%.

Example. The heat of the flue gases is utilized using the network economizer 6 installed in the downward gas duct of the boiler 1 between the electrostatic precipitator 4 and the smoke exhauster 5. The initial temperature of the network water is t ' _sv = 5 ° C, which is achieved by using a heat pump installation in the heating system circuit in the third stage 16 heat transfer. The heat of the mains water is triggered by the heat consumer at the maximum heat load and the temperature graph at the first heat transfer stage 14 t ^start _sv / t '' ^1s _sv = 150 ° C / 70 ° C according to the traditional scheme. The thermal share of the consumer in the first stage 14 is α ^1s = 0.55. The heat consumer in the second stage 15 of heat transfer heat is triggered when the temperature schedule t ' ^2s _sv / t'' ^2s _sv = 70 ° C / 45 ° C due to changes in speed and build-up heating surface of the heating devices. The thermal share of the consumer in the second stage 15 is α ^2c = 0.17. The heat consumer produces heat at the third heat transfer stage 16 at the temperature graph t ' ^HPP _sv / t'' ^HPP _sv = 70 ° C / 45 ° C due to the water heated by the heat taken in the heat pump unit 17 from the return network water that passed the first 14 and the second 15 stages of heat transfer in the circuit of the heating system, as well as due to a change in its speed mode of movement in the pipeline and an increase in the heating surface of heating devices, with a final decrease in the temperature graph t ' ^3с _sv / t'' ^3s _s = 45 ° C / 5 ° C. The thermal share of the consumer is third to us Upenu ^3c is α = 0.28.

The above allows us to conclude about the technical feasibility and economic feasibility of applying a comprehensive technology that includes deep, using the heat of formation, utilization of the heat of the exhaust gases, their additional purification from ash, sulfur and nitrogen oxides and the accumulation of heat received.

Claims (15)

1. The district heating system, comprising a steam boiler with a combustion chamber and flues, in which there are steam heating surfaces that are closed through a steam turbine or directly to network heaters, a direct and reverse network water circuit, a heating system circuit with a heat pump installation located at a heating station the condenser output of which is connected to the final heat transfer stage of the heating system circuit, and the evaporator output of which is connected to the return chilled network water return circuit for heating into network heaters, characterized in that the return chilled network water circuit is equipped with at least one well for accumulating excess chilled network water in the soil stratum, and for preheating the cooled network water with the heat of exhaust gases using the heat of vaporization in the boiler flue network economizer, as well as for accumulating during the inter-heating period heated in the network economizer and / or heated in network heaters of network water to direct delivery water tour is equipped with at least one heat-insulated reservoir. 2. The system according to claim 1, characterized in that the additional network economizer is installed in the gas duct of the boiler outside the combustion chamber. 3. The system according to claim 1, characterized in that the heating system circuit is equipped with at least three heat transfer stages. 4. The system according to claim 3, characterized in that the first stage of heat transfer is performed according to the traditional scheme. 5. The system according to claim 3, characterized in that the second stage of heat transfer is made with a modified high-speed mode of movement of water in the pipeline, and / or an increased heat transfer surface, and / or a modified type of heating devices. 6. The system according to claim 3, characterized in that the third stage of heat transfer is performed using water heated in the condenser of the heat pump installation with return network water that has passed the first and second stages of heat transfer, as well as with a modified high-speed mode of movement of water in the pipeline and / or increased heat transfer surface and / or a modified type of heating device. 7. The system according to claim 1, characterized in that the heat power equipment, well, reservoir and pipelines are equipped with pumps, shut-off and control valves. 8. The method of district heating, according to which fuel is burned in the boiler’s combustion chamber, steam is obtained in the heating surfaces located in the boiler’s combustion chamber and gas ducts, which is used to generate electric and / or thermal energy, and to produce the latter, they are heated in network heaters direct network water with steam and feed it into the heating system circuit, where the network water that has passed the initial stages of heat transfer in the heating system circuit is cooled in the heat pump evaporator, and the heat removed near the return network water, water is heated in the condenser of the heat pump, which is supplied to the heating system circuit to pass the final stage of heat transfer, while the return cooled network water is returned for heating to the network heaters, characterized in that the excess return cooled network water is accumulated at least in one well in the thickness of the soil, and when consumed, the cooled network water is preheated with the heat of the exhaust gases, using the heat of vaporization, in network economization e additionally installed in the flue of the boiler, and then heated in the economizer network and / or heated in the water mains network heaters fed into the heating circuit, and in interheating period accumulate in at least one heat-insulated reservoir outline direct network water. 9. The method according to claim 8, characterized in that the network water heated in the network economizer and / or heated in the network heaters is supplied to the circuit of the heating system, where it passes through three stages of heat transfer. 10. The method according to claim 9, characterized in that in the first stage the heat transfer is carried out according to the traditional scheme. 11. The method according to claim 9, characterized in that in the second stage, heat transfer is carried out by changing the high-speed mode of movement of water in the pipeline, and / or increasing the surface of heat transfer, and / or changing the type of heating devices. 12. The method according to claim 9, characterized in that in the third stage the heat transfer is carried out with water heated in the condenser of the heat pump installation by the network water that has passed the first and second heat transfer stages in the heating system circuit, as well as by changing the speed mode of the water movement in the pipeline, and / or increasing the surface of heat transfer, and / or changing the type of heaters. 13. The method according to claim 8, characterized in that before accumulating in a thermally insulated pond, the temperature of the network water heated in the network heaters is lowered to the temperature of the network water heated in the network economizer. 14. The method according to item 13, wherein the temperature of the network water heated in the network heaters is lowered by mixing with reverse chilled network water. 15. The method according to claim 8, characterized in that the mode of operation of the heat power equipment, the well and the insulated reservoir, as well as the direction and speed of the water in the pipelines are controlled by pumps, shut-off and control valves.

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