RU2315185C1 - Method of operation of thermal power station - Google Patents

Abstract

FIELD: heat power engineering.

SUBSTANCE: in periods of reduced load on thermal power station, increased extraction of steam from turbine extractions is done. Said steam is used to heat reserve high-temperature heat carrier to 250-300°C, and at peak hours, flow of return heating water is divided into two parallel flows, first of which including 10-30% of return heating water is heated to temperature of 250-300°C at pressure of 4.0-8.6 and then is mixed with second flow and delivered by injector-mixer into turbine system heaters. Used as active liquids in injector is return heating water of first flow, and as passive liquid, water of second flow. Invention provides reduction of consumption characteristics of transfer pumps, reduction of overall dimensions of heat exchange equipment and capital outlays for construction of power stations.

EFFECT: increased efficiency and maneuverability of stations.

3 cl, 1 dwg

Description

The invention relates to a power system and can be used in thermal and nuclear power plants.

A known scheme of a coal thermal power plant (TPP) with indirect accumulation of feed water, consisting of a steam-power circuit of a turbine unit, an oil storage circuit and a peak turbine circuit in the form of an add-on to the main steam turbine installation (see G. Beckman, P. Gilly "Thermal energy storage", MIR Publishing House, 1987, p. 233, Fig. 7.16.). The scheme of the said TPP and the method implemented by it allow eliminating the rigid dependence of the simultaneous production of heat and electric load, and mitigating the tension in the coating of peak loads. However, the main disadvantage of the known scheme and the method it implements is the complicated operation technology due to the presence of additional circuits of the peak turbine and oil accumulator, which in cases of prolonged shutdown leads to the difficulty of putting them into operation, as well as to a significant increase in the station's costs for their construction.

A known method of operation of a thermal power plant, comprising a cogeneration turbine with heating steam extraction, to which are connected network heaters, a boiler, included in the pipelines of the heating system, network pumps. In this method, the water coming from the consumer is divided into two parallel flows, one of which is heated in the basic mode in the network heaters, and the other in the peak mode in the boiler, and the network water flows are mixed before being supplied to the consumer (see ed. Certificate of the USSR 2148174, IPC 7 F01K 17/02 of 12/15/1998). The known method can improve the reliability and efficiency of the thermal power plant, however, it does not allow to increase the maneuverability and efficiency of the power plant in the modes of regulation of the schedule of electric and thermal loads. In addition, the implementation of the method involves the use of a number of transfer pumps, which consume a significant amount of electricity.

The specified method, as the closest in its technical essence to the proposed one, is selected as a prototype.

The proposed invention solves the problems:

- reduction of capital costs for the construction of a thermal energy storage system (SATE);

- reducing the flow characteristics of the transfer pumps, reducing the dimensions of heat exchangers and pipelines of the SATE circuit.

To achieve these tasks, a method of operating a thermal power plant is proposed, in which the return network water from consumers is divided into two parallel flows, at least one of which is heated, after which the flows are mixed; moreover, during periods of decreasing electric load, the reserve stock of high-temperature coolant (VTT) is heated with steam from a turbine take-off to a temperature of 250-300 ° С, and when the electric load is increased, 10-30% of return network water is allocated as the first stream, it is heated at a pressure of 4, 0-8.6 MPa to a temperature of 250-300 ° C with hot HTT, after which, using an injector-mixer, in which the first stream of reverse network water heated under pressure is used as the active liquid and the second stream is used as the passive liquid, they are mixed both streams and supply the resulting mixture to the turbine network heaters.

It is also advisable to use silicone oil or synthetic heat transfer agent, mainly Thermolan or Dauterm brands, as VTT.

Distinctive features of the proposed method in comparison with the prototype is that during periods of decreasing electric load, the reserve stock of high-temperature coolant is heated with steam from turbine offsets to a temperature of 250-300 ° C, and during periods of increasing electric load, 10-30% of the return net water, it is heated at a pressure of 4.0-8.6 MPa to a temperature of 250-300 ° C with hot HTT, and then using an injector-mixer, in which the first heated under pressure is used as the active liquid th stream of reverse network water and, as a passive liquid, a second stream, mix both streams and supply the resulting mixture to the turbine network heaters.

The steam sampling of a turbine with a temperature of 250-300 ° C, carried out during periods of lowering the electrical load, provides intensive heating of the silicone or synthetic coolant, which within its specified limits remains stable and is not subjected to coking or decomposition.

The heating of the extracted reverse water flow by hot HTT to a temperature of 250-300 ° C is carried out without boiling water, since it occurs at a pressure of 4.0-8.6 MPa.

As a result, part of the return network water (first stream) with a temperature of 250-300 ° C and a pressure of 4.0-8.6 MPa is used as an active liquid in the mixer injector, while the rest of the network water (second stream) is used as passive liquids.

The ratio of flow rates into which reverse network water is divided is determined by the conditions for obtaining the required temperature of the network water at the outlet of the injector-mixer, which is maintained depending on the outdoor temperature according to the temperature schedule of the heating system.

The proposed method is considered as an example of the operation of a thermal power plant, the circuit diagram of which is shown in the drawing.

Thermal power station contains: steam generator 1; steam turbine unit 2 with steam withdrawals 3 and 4, connected respectively to a standard network water heater 5 (to its inlet through a heating medium) and a high-temperature coolant heater 6 (to its inlet to a heating medium); a condenser 7 of the steam turbine installation 2 with a condensate supply path 8 by the condensate pump 9 through the low pressure heaters (PND) 10 to the deaerator 11 and then by the feed pump 12 through the high pressure heaters 13 (LDPE) to the steam generator 1; network water pipe 14, in the cuts of which a standard network water heater 5 and a boiler 15 are installed. The thermal power station is also equipped with a heat accumulator containing containers for storing cold 16 and hot 17 high-temperature coolant (VTT), interconnected by a heat-exchange-accumulating circuit 18 including the flow part (in the heated medium) of the VTT 6 heater, the flow part (in the heating medium) of the high-temperature return network water heater 19, circulation pumps 20 cold and hot 21 VTT. The cold VTT circulation pump 20 is connected by its suction collector to a capacity of 16 for storage of cold VTT, and its pressure collector is connected to the input (via the heated medium) of the VTT 6 heater, the output of which (via the heated medium) is connected to the capacity of 17 for the storage of hot VTT. The hot VTT circulation pump 21 is connected by its suction collector to a tank 17 for storing hot VTT, and its pressure collector is connected to the inlet (via heating medium) of a high-temperature return network water heater 19, the outlet of which (via heating medium) is connected to a cold storage tank 16 VTT. The thermal power station also contains a return network water pipe 22 with two parallel branches of reverse network water (WWS) 23 and 24, the first of which 23 is equipped with a high-pressure pump 25, connected by its pressure collector to the input (via a heated medium) of the high-temperature heater 25, the output of which (via a heated medium) is connected to the pump line (active liquid supply line) 26 of the injector-mixer 27 included in the second parallel branch of the WWS 24 so that its ejected line (supply line is passive th fluid) 28 and pressure line 29 provide the connection of the second parallel branch of the WWS 24 to the input (via the heated medium) of the standard network water heater 5. In turn, the output (via the heating medium) of the standard network water heater 5 is connected to the condensate supply path 8 (via PND 6) to the deaerator 11 and further (through the LDPE 13) to the steam generator 1.

To connect and disconnect the boiler 15, it is equipped with a bypass pipe 30 and shut-off and control valves 31 and 32, the first of which is located on the bypass section of the pipeline 30, and the rest on the bypassed section of the pipeline.

To change the flow values along the two branches of the OSV 23, 24, shut-off and control valves 33, 34 are used, respectively.

The OSV 35 main pump is connected by its pressure collector to the inlet (according to the heated medium) of the standard network water heater 5, and its suction collector is connected to the pressure line 29 of the injector-mixer 27. The OSV 35 main pump is used in modes of heat supply to consumers from turbine withdrawals, and during peak hours - in the mode of discharge of the heat accumulator, it can be turned off. To control the operation of the main pump OSV 35, turn it on and off, it is equipped with a bypass pipe 36 and shut-off and control valves 37, 38, the first of which is located on the bypass section of the pipeline 36, and the rest on the bypassed section of the pipeline.

To simplify the start and control the operation of the injector-mixer 27, a shut-off and control valve 39 is used, which is installed in the pump line 26 of the injector-mixer 27.

Implementation of the proposed method is carried out during operation of the given station as follows.

During periods of a decrease in the electric load of a power plant (usually at night), increased steam is taken from the 3, 4 turbine 2 withdrawals, which are used to heat the high-temperature coolant (VTT) in the VTT 6 heater and mains water in a standard heater 5. The periods of station load reduction are charging time of the heat accumulator when a cold VTT (with a temperature of about 60-80 ° C) from a cold storage VTT storage tank 16 is supplied with a cold VTT circulation pump 20 to the VTT 6 heater. After heating and VTT it is stored in a tank 17 for storing hot VTT. The condensate of the selected steam after the heaters is returned to the main path 8 of the feed water.

During periods of increasing electric load of the power plant (during peak hours), the accumulated hot VTT from the storage tank 17 is fed by a circulation pump 21 to the inlet (through the heating medium) of the high-temperature heater OSV 19, the output of which (through the heating medium) is connected to the tank 16 for cold VTT storage. On the other hand, at the input (over a heated medium) of a high-temperature WWS heater 19, only a part of the return network water flow (10-30%) is supplied using a high-pressure pump 25 (under a pressure of 4.0-8.6 MPa). The specific amount of WWS supplied by the high-pressure pump 25 depends on the outdoor temperature, the operating mode of the high-temperature OSV 19 heater, and the temperature schedule of the heating system.

Heated water under pressure (which eliminates its boiling at temperatures of 250-300 ° C) is fed into the pump line 26 of the injector-mixer 27, where it is used as an active liquid. The remaining flow of return network water is directed to the ejected line 28 of the injector-mixer 29, where it is used as a passive liquid. Mixing in the injector-mixer 27, both flows 23, 24 of the return network water acquire the total temperature provided by the temperature schedule of heat release, and enter the input (via a heated medium) of a standard heater 5 of network water through the bypass pipe 36 (or along the main path of the main pump 35 OSV, which is ensured by the overlapping of the pipeline 36 with a shut-off and control valve 37 with open shut-off-control valves 38).

The network water passing through the standard heater 5 is supplied (through or bypassing the boiler 15) to the external heating network 14. As the network water enters the standard heater 5 already heated, the steam 3 is automatically shut off and the steam flow through the flow part of the turbine 2 increases, which causes an increase in the power of the turbine unit, since the cogeneration turbine in this case works as a condensation turbine.

By heating part of the network water under pressure to the temperature of a high-temperature coolant, the conditions for intensive heat transfer of media are created, which significantly reduces the dimensions of the heat exchangers and pipelines of the circuit of the thermal energy storage system. This leads to a reduction in the cost of their construction. In addition, the use, together with the heat storage system, of such means of supplying network water as injectors makes it possible to "utilize" the excess pressure of the medium (at which it was previously heated at high temperature), which ensures a reduction in the flow characteristics of transfer pumps.

Claims (3)

1. The method of operation of a thermal power plant, in which the return network water coming from consumers is divided into two parallel flows, at least one of which is heated, after which the flows are mixed and maintain the temperature of the network water depending on the outdoor temperature according to the temperature schedule of the heating network, characterized in that in periods of decreasing electrical load, the reserve stock of high-temperature coolant (VTT) is heated with steam from turbine offsets to a temperature of 250-300 ° C, and in periods of higher The electric load is extracted as the first flow of 10-30% reverse network water, it is heated at a pressure of 4.0-8.6 MPa to a temperature of 250-300 ° C with hot HTT, and then using an injector mixer, in which, as active liquid, the first stream of reverse network water heated under pressure is used, and the second stream is used as passive liquid, the two flows of reverse network water are mixed and the resulting mixture is fed into turbine network heaters. 2. The method of operation of a thermal power plant according to claim 1, characterized in that silicone oil is used as the HTT. 3. The method of operation of a thermal power plant according to claim 1, characterized in that a synthetic heat transfer medium, preferably "Thermolan" or "Dauterm", is used as the HTT.