A high-pressure feed water bypass frequency modulation system and operating method for a thermal power plant equipped with a heat pump

Abstract

The present invention discloses a high-pressure feedwater bypass frequency modulation system and a working method for a thermal power plant equipped with a heat pump. In the present invention, the high-pressure cylinder is connected to a high-pressure heat recovery heater and a small steam turbine, the medium and low-pressure cylinders are connected to a steam storage tank, the small steam turbine drives a feedwater pump to perform work, the feedwater pump is connected to the high-pressure heat recovery heater, the steam storage tank is connected to a bypass, the bypass is connected to a deaerator, and the deaerator is connected to the feedwater pump. The present invention combines a heat pump with a high-pressure feedwater bypass thermal power unit. When the unit participates in a primary frequency modulation, the steam intake of the small steam turbine is adjusted to reduce or increase the amount of steam entering the unit to perform work, thereby achieving the purpose of reducing or increasing the unit power. At the same time, combined with the characteristics of the absorption heat pump, the feedwater temperature of the boiler is adjusted to ensure stable operation of the boiler.

Description

Technical Field

[0001] The present invention belongs to the field of thermal power generation units, and in particular relates to a high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump and a working method thereof. Background Art

[0002] With the large-scale integration of renewable energy sources such as wind and solar power, the grid is placing increasing demands on thermal power units to absorb these renewable energy sources. However, due to the instability of solar and wind power supply, effective daily forecasting of renewable energy production is currently unavailable. This leads to fluctuations in the grid frequency, impacting power supply quality. Thermal power units offer a certain degree of flexibility in participating in peak and frequency regulation, so improving their frequency regulation capabilities is a key research area. Currently, key frequency regulation methods include ultra-high pressure (UHP) throttling, condensate throttling, and high-pressure heater (HPHT) feedwater bypass. However, UHP throttling involves throttling main steam, resulting in significant energy losses. Condensate throttling has a weaker frequency regulation capability than high-pressure heater (HPHT) feedwater bypass. Furthermore, the HPHT feedwater bypass frequency regulation method can easily cause fluctuations in boiler feedwater temperature, impacting stable boiler operation. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a high-pressure feed water bypass frequency regulation system and working method for a thermal power plant equipped with a heat pump, apply the heat pump to the thermal power unit, and configure a steam pressure tank to participate in the frequency regulation, thereby improving the unit's ability to participate in frequency regulation.

[0004] In order to achieve the above-mentioned purpose, a high-pressure feedwater bypass frequency regulation system for a thermal power plant equipped with a heat pump includes a boiler, the boiler is connected to a high-pressure cylinder, the high-pressure cylinder is connected to a medium- and low-pressure cylinder, the steam outlet of the high-pressure cylinder is connected to a small steam turbine, the rotation of the small steam turbine drives the feedwater pump to do work, the feedwater pump is connected to the tube-side water inlet end of the high-pressure regenerator, the high-pressure cylinder and the shell side of the high-pressure regenerator are connected by a steam extraction pipeline, the tube-side water outlet end of the high-pressure regenerator is finally connected to the boiler, the extraction steam of the medium- and low-pressure cylinders is connected to the steam storage tank through a pipeline, the steam storage tank is connected to the bypass, the bypass is connected to the deaerator, and the deaerator is connected to the feedwater pump.

[0005] The bypass includes a condenser, the heat exchanger inlet of the condenser is connected to the deaerator, the heat exchanger outlet of the condenser is connected to the heat exchanger inlet of the absorber, the heat exchanger outlet of the absorber is connected to the feed water inlet of the boiler, the steam storage tank is connected to the heat exchanger inlet of the generator and the heat exchange working medium inlet of the absorber, the heat exchanger outlet of the generator is connected to the deaerator, the heat exchange working medium outlet of the absorber is connected to the solution heat exchanger, the solution heat exchanger is connected to the heat exchange working medium inlet of the generator, the heat exchange working medium outlet of the generator is connected to the heat exchange working medium inlet of the condenser and the solution pump, the solution pump is connected to the solution heat exchanger, the solution heat exchanger is connected to the absorber, the condensate outlet of the condenser is connected to the condenser circulation pump, and the condenser circulation pump is finally connected to the deaerator.

[0006] An electric water supply pump is provided on the connecting pipeline between the deaerator and the condenser, and a generator circulation pump is provided on the connecting pipeline between the generator and the deaerator.

[0007] A generator steam extraction regulating valve is provided on the connecting pipeline between the steam storage tank and the generator, an absorber steam extraction regulating valve is provided on the connecting pipeline between the steam storage tank and the absorber, and a high-pressure heater bypass regulating valve is provided on the connecting pipeline between the deaerator and the condenser.

[0008] A steam storage tank extraction valve is provided on the connecting pipeline between the medium and low pressure cylinders and the steam storage tank.

[0009] An inlet regulating valve is provided on the connecting pipeline between the high-pressure cylinder and the small steam turbine.

[0010] The exhaust outlets of the medium and low pressure cylinders and the small steam turbine are connected to the condenser, the condenser is connected to the condensate pump, and the condensate pump is connected to the deaerator.

[0011] A method for operating a high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump, characterized by comprising the following steps:

[0012] When the unit is running, the medium and low pressure cylinders send the extracted steam into the steam storage tank, and a part of the steam is stored in the steam storage tank;

[0013] During the load reduction process of the unit, the amount of steam entering the small steam turbine from the high-pressure cylinder is increased, the flow rate of the small steam turbine feed water pump is increased, the amount of steam entering the small steam turbine is increased, the inlet water flow rate of the high-pressure heat recovery heater is increased, the heat exchange temperature rise on the tube side of the high-pressure heat recovery heater will be reduced, the outlet temperature of the high-pressure heat recovery heater tube side is reduced, the shell side pressure of the high-pressure heat recovery heater is reduced, the pressure difference between the upper and lower sides of the extraction pipe is increased, the amount of steam extracted from the high-pressure heat recovery heater is increased, the amount of steam entering the steam turbine to do work is reduced, the output power of the steam turbine is reduced, the extraction amount of the high-pressure heat recovery heater is increased, the heat obtained at the feed water outlet of the high-pressure heat recovery heater is increased, the flow rate of the transmission bypass is reduced, and the heat absorbed by the bypass feed water from the heat pump is reduced;

[0014] During the load increase process of the unit, the amount of steam entering the small steam turbine from the high-pressure cylinder is reduced, the flow rate of the small steam turbine feed water pump is reduced, the amount of steam entering the small steam turbine is reduced, the inlet water flow rate of the high-pressure heat recovery heater is reduced, the heat exchange temperature rise on the tube side of the high-pressure heat recovery heater will increase, the outlet temperature on the tube side of the high-pressure heat recovery heater increases, the pressure on the shell side of the high-pressure heat recovery heater increases, the pressure difference between the upper and lower sides of the extraction pipe decreases, the amount of steam extracted from the high-pressure heat recovery heater is reduced, the amount of steam entering the steam turbine to do work increases, the output power of the steam turbine increases, the extraction amount of the high-pressure heat recovery heater is reduced, the heat obtained at the feed water outlet of the high-pressure heat recovery heater is reduced, the flow rate of the transmission bypass is increased, and the heat absorbed by the bypass feed water from the heat pump is increased.

[0015] When reducing the amount of heat absorbed by the bypass feed water from the heat pump, reduce the opening of the absorber steam extraction regulating valve and the generator steam extraction regulating valve.

[0016] When the amount of heat absorbed by the bypass feed water from the heat pump is increased, the opening of the absorber steam extraction regulating valve and the generator steam extraction regulating valve is increased.

[0017] Compared with the prior art, the high-pressure cylinder of the present invention is connected to the high-pressure heat recovery heater and the small steam turbine, the medium and low-pressure cylinders are connected to the steam storage tank, the small steam turbine is connected to the high-pressure heat recovery heater through the feed water pump, the steam storage tank is connected to the bypass, the bypass is connected to the deaerator, and the deaerator is connected to the feed water pump. The present invention combines the heat pump with the high-pressure feed water bypass thermal power unit. When the unit participates in the primary frequency modulation, the steam intake of the small steam turbine is adjusted to reduce or increase the amount of steam entering the unit to do work, so as to achieve the purpose of reducing or increasing the unit power. At the same time, combined with the characteristics of the absorption heat pump, the feed water temperature of the boiler is adjusted to ensure stable operation of the boiler.

[0018] Furthermore, the present invention utilizes a heat pump to regulate the boiler feed water temperature, thereby achieving cascade utilization of energy and improving energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a system diagram of the present invention;

[0020] Among them, 1 is the boiler, 2 is the high-pressure cylinder of the steam turbine, 3 is the medium and low-pressure cylinders of the steam turbine, 4 is the condenser, 5 is the condensate pump, 6 is the small steam turbine, 7 is the small steam turbine inlet regulating valve, 8 is the deaerator, 9 is the small steam turbine feed water pump, 10 is the high-pressure heat recovery heater, 11 is the electric feed water pump, 12 is the high-pressure heater bypass regulating valve, 13 is the generator circulation pump, 14 is the condenser, 15 is the absorber, 16 is the condenser circulation pump, 17 is the solution heat exchanger, 18 is the solution pump, 19 is the throttle valve, 20 is the generator, 21 is the steam storage tank, 22 is the heat storage tank extraction valve, 23 is the generator extraction regulating valve, and 24 is the absorber extraction regulating valve. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] See also Figure 1 A high-pressure feedwater bypass frequency regulation system for a thermal power plant equipped with a heat pump includes a boiler 1, the boiler 1 is connected to a high-pressure cylinder 2, the high-pressure cylinder 2 is connected to a medium- and low-pressure cylinder 3, the steam outlet of the high-pressure cylinder 2 is connected to a small steam turbine 6, the small steam turbine 6 drives a feedwater pump 9 to do work, the feedwater pump 9 is connected to the tube-side water inlet end of a high-pressure regenerator 10, the high-pressure cylinder 2 and the shell side of the high-pressure regenerator 10 are connected through a steam extraction pipeline, the tube-side water outlet end of the high-pressure regenerator 10 is finally connected to the boiler 1, the extraction steam of the medium- and low-pressure cylinders 3 is connected to a steam storage tank 21 through a pipeline, the steam storage tank 21 is connected to a bypass, the bypass is connected to a deaerator 8, and the deaerator 8 is connected to the feedwater pump 9.

[0023] The bypass includes a condenser 14, the heat exchanger inlet of the condenser 14 is connected to the deaerator 8, the heat exchanger outlet of the condenser 14 is connected to the heat exchanger inlet of the absorber 15, the heat exchanger outlet of the absorber 15 is connected to the feed water inlet of the boiler 1, the steam storage tank 21 is connected to the heat exchanger inlet of the generator 20 and the heat exchange working medium inlet of the absorber 15, the heat exchanger outlet of the generator 20 is connected to the deaerator 8, the heat exchange working medium outlet of the absorber 15 is connected to the solution heat exchanger 17, the solution heat exchanger 17 is connected to the heat exchange working medium inlet of the generator 20, the heat exchange working medium outlet of the generator 20 is connected to the heat exchange working medium inlet of the condenser 14 and the solution pump 18, the solution pump 18 is connected to the solution heat exchanger 17, the solution heat exchanger 17 is connected to the absorber 15, the condensate outlet of the condenser 14 is connected to the condenser circulation pump 16, and the condenser circulation pump 16 is connected to the deaerator 8. The exhaust outlets of the medium and low pressure cylinders 3 and the small steam turbine 6 are both connected to the condenser 4, which is connected to the condensate pump 5, which is ultimately connected to the deaerator 8. An electric feedwater pump 11 is installed on the pipeline connecting the deaerator 8 to the condenser 14, and a generator circulation pump 13 is installed on the pipeline connecting the generator 20 to the deaerator 8.

[0024] The pipeline connecting the steam accumulator 21 to the generator 20 is equipped with a generator extraction regulating valve 23. The pipeline connecting the steam accumulator 21 to the absorber 15 is equipped with an absorber extraction regulating valve 24. The pipeline connecting the deaerator 8 to the condenser 14 is equipped with a high-pressure heater bypass regulating valve 12. The pipeline connecting the intermediate and low-pressure cylinders 3 to the steam accumulator 21 is equipped with a steam accumulator extraction valve 22. The pipeline connecting the high-pressure cylinder 2 to the small steam turbine 6 is equipped with an inlet regulating valve 7.

[0025] A method for operating a high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump, characterized by comprising the following steps:

[0026] When the unit is running, the medium and low pressure cylinders 3 send the extracted steam into the steam storage tank 21, and a part of the steam is stored in the steam storage tank;

[0027] During the load reduction process of the unit, the amount of steam entering the small steam turbine 6 from the high-pressure cylinder 2 is increased, the flow rate of the small steam turbine feed water pump 9 is increased, the amount of steam entering the small steam turbine is increased, the inlet water flow rate of the high-pressure heat recovery heater 10 is increased, the heat exchange temperature rise on the tube side of the high-pressure heat recovery heater 10 will be reduced, the outlet temperature of the tube side of the high-pressure heat recovery heater 10 is reduced, the shell side pressure of the high-pressure heat recovery heater 10 is reduced, the pressure difference between the upper and lower sides of the extraction pipe is increased, the amount of steam extracted by the high-pressure heat recovery heater 10 is increased, the amount of steam entering the steam turbine to do work is reduced, the output power of the steam turbine is reduced, the extraction amount of the high-pressure heat recovery heater 10 is increased, the heat obtained at the feed water outlet of the high-pressure heat recovery heater 10 is increased, the flow rate of the transmission bypass is reduced, the opening degree of the absorber extraction steam regulating valve 24 and the generator extraction steam regulating valve 23 is adjusted to reduce the heat absorbed by the bypass feed water from the heat pump;

[0028] During the load increase process of the unit, the amount of steam entering the small steam turbine 6 from the high-pressure cylinder 2 is reduced, the flow rate of the small steam turbine feed water pump 9 is reduced, the amount of steam entering the small steam turbine 6 is reduced, the inlet water flow rate of the high-pressure heat recovery heater 10 is reduced, the heat exchange temperature rise on the tube side of the high-pressure heat recovery heater 10 will increase, the outlet temperature of the tube side of the high-pressure heat recovery heater 10 increases, the shell side pressure of the high-pressure heat recovery heater 10 increases, the pressure difference between the upper and lower sides of the extraction pipe decreases, the amount of steam extracted from the high-pressure heat recovery heater 10 is reduced, the amount of steam entering the steam turbine to do work increases, the output power of the steam turbine increases, the extraction amount of the high-pressure heat recovery heater 10 is reduced, the heat obtained at the feed water outlet of the high-pressure heat recovery heater 10 is reduced, the flow rate of the transmission bypass is increased, the opening of the absorber extraction steam regulating valve 24 and the generator extraction steam regulating valve 23 is adjusted to increase the heat absorbed by the bypass feed water from the heat pump.

[0029] The present invention can apply a heat pump to a thermal power unit, and simultaneously configure a steam pressure tank to participate in frequency regulation, thereby improving the unit's ability to participate in frequency regulation.

Claims

1. A high-pressure feed water bypass frequency modulation system for a thermal power plant equipped with a heat pump, characterized in that: The boiler (1) is connected to the high-pressure cylinder (2) of the steam turbine, the high-pressure cylinder (2) of the steam turbine is connected to the medium- and low-pressure cylinders (3) of the steam turbine, the steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the small steam turbine (6), the small steam turbine (6) drives the small steam turbine feed water pump (9), the small steam turbine feed water pump (9) is connected to the pipe side water inlet end of the high-pressure regenerative heater (10), the shell side of the high-pressure cylinder (2) of the steam turbine and the high-pressure regenerative heater (10) are connected through a steam extraction pipeline, the pipe side water outlet end of the high-pressure regenerative heater (10) is finally connected to the boiler (1), the extraction steam of the medium- and low-pressure cylinders (3) of the steam turbine is connected to the steam storage tank (21) through a pipeline, the steam storage tank (21) is connected to a bypass, the bypass is connected to a deaerator (8), and the deaerator (8) is connected to the small steam turbine feed water pump (9); The bypass includes a condenser (14), the heat exchanger inlet of the condenser (14) is connected to the deaerator (8), the heat exchanger outlet of the condenser (14) is connected to the heat exchanger inlet of the absorber (15), the heat exchanger outlet of the absorber (15) is connected to the feed water inlet of the boiler (1), the steam storage tank (21) is connected to the heat exchanger inlet of the generator (20) and the heat exchange medium inlet of the absorber (15), the heat exchanger outlet of the generator (20) is connected to the deaerator (8), the heat exchange medium inlet of the absorber (15) is connected to the heat exchanger inlet of the generator (20). The heat exchange outlet of the generator (20) is connected to the heat exchange medium inlet of the generator (14), the heat exchange medium outlet of the generator (20) is connected to the heat exchange medium inlet of the condenser (14) and the solution pump (18), the solution pump (18) is connected to the solution heat exchanger (17), the solution heat exchanger (17) is connected to the absorber (15), the condensate outlet of the condenser (14) is connected to the condenser circulation pump (16), and the condenser circulation pump (16) is connected to the deaerator (8); A steam storage tank extraction valve (22) is provided on the connecting pipeline between the steam turbine medium and low pressure cylinders (3) and the steam storage tank (21); A generator steam extraction regulating valve (23) is provided on the connecting pipeline between the steam storage tank (21) and the generator (20), an absorber steam extraction regulating valve (24) is provided on the connecting pipeline between the steam storage tank (21) and the absorber (15), and a high-pressure heater bypass regulating valve (12) is provided on the connecting pipeline between the outlet of the deaerator (8) and the condenser (14); A small steam turbine inlet regulating valve (7) is provided on the connecting pipeline between the steam turbine high-pressure cylinder (2) and the small steam turbine (6).

2. A high-pressure feed water bypass frequency modulation system for a thermal power plant equipped with a heat pump according to claim 1, characterized in that: An electric water supply pump (11) is provided on the connecting pipeline between the outlet of the deaerator (8) and the condenser (14), and a generator circulation pump (13) is provided on the connecting pipeline between the generator (20) and the deaerator (8).

3. The high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump according to claim 1, characterized in that: The exhaust outlets of the medium and low pressure cylinders (3) of the steam turbine and the small steam turbine (6) are connected to the condenser (4), the condenser (4) is connected to the condensate pump (5), and the condensate pump (5) is finally connected to the deaerator (8).

4. A method for operating a high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump according to claim 1, characterized in that: The following steps are involved: When the unit is running, the steam turbine's medium and low pressure cylinders (3) send extracted steam into the steam storage tank (21), and a portion of the steam is stored in the steam storage tank (21); During the load reduction process of the unit, the amount of steam entering the small steam turbine (6) from the high-pressure cylinder (2) of the steam turbine is increased, the flow rate of the small steam turbine feed water pump (9) is increased, the amount of steam entering the small steam turbine is increased, the inlet water flow rate of the high-pressure regenerative heater (10) is increased, the heat exchange temperature rise on the tube side of the high-pressure regenerative heater (10) is reduced, the outlet temperature of the tube side of the high-pressure regenerative heater (10) is reduced, the shell side pressure of the high-pressure regenerative heater (10) is reduced, the pressure difference between the upper and lower sides of the extraction pipe is increased, the amount of steam extracted by the high-pressure regenerative heater (10) is increased, the amount of steam entering the steam turbine to do work is reduced, the output power of the steam turbine is reduced, the extraction amount of the high-pressure regenerative heater (10) is increased, the heat obtained at the feed water outlet of the high-pressure regenerative heater (10) is increased, the flow rate of the transmission bypass is reduced, and the heat absorbed by the bypass feed water from the heat pump is reduced; During the process of increasing the load of the unit, the amount of steam entering the small steam turbine (6) from the high-pressure cylinder (2) of the steam turbine is reduced, the flow rate of the small steam turbine feed water pump (9) is reduced, the amount of steam entering the small steam turbine (6) is reduced, the inlet water flow rate of the high-pressure regenerative heater (10) is reduced, the heat exchange temperature rise on the tube side of the high-pressure regenerative heater (10) will increase, the outlet temperature of the tube side of the high-pressure regenerative heater (10) increases, the shell side pressure of the high-pressure regenerative heater (10) increases, the pressure difference between the upper and lower sides of the extraction pipe is reduced, the amount of steam extracted from the high-pressure regenerative heater (10) is reduced, the amount of steam entering the steam turbine to do work increases, the output power of the steam turbine increases, the extraction amount of the high-pressure regenerative heater (10) is reduced, the heat obtained at the feed water outlet of the high-pressure regenerative heater (10) is reduced, the flow rate of the transmission bypass is increased, and the heat absorbed by the bypass feed water from the heat pump is increased.

5. The operating method of the high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump according to claim 4, characterized in that: When reducing the amount of heat absorbed by the bypass feed water from the heat pump, the openings of the absorber steam extraction regulating valve (24) and the generator steam extraction regulating valve (23) are reduced.

6. The operating method of the high-pressure feed water bypass frequency modulation system of a thermal power plant equipped with a heat pump according to claim 4, characterized in that: When the amount of heat absorbed by the bypass feed water from the heat pump is increased, the openings of the absorber steam extraction regulating valve (24) and the generator steam extraction regulating valve (23) are increased.

Images