Coal-fired power generation steam and heat pump integrated energy storage system and operation method thereof

Abstract

The invention discloses a coal-fired power generation steam and heat pump integrated energy storage system and an operation method thereof. The system comprises a coal-fired unit coupling fused salt energy release system and a reheat steam coupling heat pump energy storage system. In the low ebb of electricity utilization, the coal-fired unit outputs electric energy to drive the heat pump charging compressor to compress a heat pump working medium, then the heat pump working medium heats the fused salt, meanwhile, part of reheat steam of the coal-fired unit sequentially heats the fused salt and a working medium at an outlet of the heat pump charging expansion machine, and the load is further reduced; and finally, redundant electric energy and part of heat energy of the reheated steam are converted into fused salt heat energy to be stored. In the peak period of electricity utilization, a part of exhaust steam of the high-pressure cylinder is heated through heat stored in the fused salt storage tank to generate reheated steam, the heat absorption capacity of main steam entering the boiler is increased under the condition that the coal consumption of the boiler is not changed, the flow of the main steam is also increased, and then the output load of the coal-fired unit is increased. According to the method, the peak regulation potential of the coal-fired unit can be exerted, the output load interval of the unit is expanded, and the method is effective for improving the peak regulation capacity of the coal-fired unit and stabilizing power grid fluctuation.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation and thermal energy storage, and in particular to a coal-fired power generation steam and heat pump integrated energy storage system and an operation method thereof. Background Art

[0002] As the main body of my country's current energy structure, coal-fired power generation units occupy a considerable proportion in my country's energy system and play the role of the main power source of my country's power industry. At present, with the rapid development of new clean energy such as wind energy and solar energy, coal-fired units are gradually turning into supporting and regulating power sources, and are more responsible for clean energy consumption and grid peak and frequency regulation. This requires coal-fired units to expand the peak regulation range under the premise of ensuring safety and further reduce the output load of the units. In view of the current difficulty in peak and frequency regulation of coal-fired units, many studies have focused on the storage and utilization of main reheat steam heat energy in coal-fired units, but this method will be limited by the minimum steam inlet of the steam turbine. The heat pump energy storage system is a large-scale power storage system based on heat storage. It can directly consume large-scale electricity while storing heat, and realize electric energy value-added heating and thermoelectric conversion through heat pump cycle and power cycle. It has the characteristics of high energy storage density and easy realization of multi-energy cogeneration. It is a highly efficient large-scale thermal energy storage technology with great potential. Applying heat pump energy storage technology to coal-fired power generation units is expected to further reduce the output load of coal-fired units and achieve safe and efficient peak load regulation of the units. However, there is currently a lack of configuration design and operation control methods for coupling steam heat storage in coal-fired power generation units with heat pump energy storage systems. Summary of the invention

[0003] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a coal-fired power generation steam and heat pump integrated energy storage system and its operation method, which reduces the minimum output load of the coal-fired unit, expands the operating range of the coal-fired unit, and improves the peak-shaving depth of the coal-fired unit.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A coal-fired power generation steam and heat pump integrated energy storage system, comprising a coal-fired unit coupled molten salt energy release system and a reheat steam coupled heat pump energy storage system; wherein,

[0006] The coal-fired unit coupled molten salt energy release system includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a low-pressure heater 7, a deaerator 8, a high-pressure heater 9, a reheat steam generator 10, a molten salt cold tank 11, a molten salt hot tank 12, a 1# molten salt pump 21, a condensate pump 22 and a feed water pump 23; the main steam outlet of the boiler 1 is connected to the steam inlet of the high-pressure cylinder 2; the feed water inlet of the boiler 1 is connected to the feed water outlet of the high-pressure heater 9; the extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the high-pressure heater 9 through a pipeline, and the steam outlet of the high-pressure cylinder 2 is respectively connected to the reheat steam inlet of the boiler 1 and the steam inlet of the reheat steam generator 10, and the second valve 25 is connected to the pipeline between the reheat steam generator 10 and the high-pressure cylinder 2; the steam inlet of the intermediate-pressure cylinder 3 is connected to the reheat steam outlet of the boiler 1 and the steam outlet of the reheat steam generator 10; the first-stage extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the high-pressure reheater 9, and the second The steam extraction outlet of the first stage is connected to the steam inlet of the deaerator 8, and the steam outlet is connected to the steam inlets of the low-pressure cylinder 4 and the low-pressure heater 7 respectively; the drain outlet of the high-pressure heater 9 is connected to the drain inlet of the deaerator 8; the intermediate steam extraction outlet of the low-pressure cylinder 4 is connected to the steam inlet of the low-pressure heater 7, and the steam outlet is connected to the steam inlet of the condenser 6; the drain outlet of the low-pressure heater 7 is connected to the drain inlet of the condenser 6; the condensate outlet of the condenser 6 is connected to the low-pressure heater 7 through the condensate pump 22. The condensate inlet of the low-pressure heater 7 is connected; the condensate outlet of the low-pressure heater 7 is connected to the condensate inlet of the deaerator 8; the feed water outlet of the deaerator 8 is connected to the feed water inlet of the high-pressure reheater 9 through the feed water pump 23; the molten salt outlet of the molten salt hot tank 12 is connected to the molten salt inlet of the reheat steam generator 10 through the 1# molten salt pump 21; the molten salt outlet of the reheat steam generator 10 is connected to the molten salt inlet of the molten salt cold tank 11; the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 are connected to the generator 5 through the transmission shaft;

[0007] The reheat steam coupled heat pump energy storage system comprises a molten salt cold tank 11, a molten salt hot tank 12, an electric motor 13, a heat pump charging compressor 14, a molten salt-working fluid heat exchanger 15, a heat pump regenerator 16, a heat pump charging expander 17, a working fluid-steam heat exchanger 18, a molten salt preheater 19 and a 2# molten salt pump 20; the working fluid outlet of the heat pump charging compressor 14 is connected to the working fluid inlet of the molten salt-working fluid heat exchanger 15; the working fluid outlet of the molten salt-working fluid heat exchanger 15 is connected to the high-temperature working fluid inlet of the heat pump regenerator 16; the high-temperature working fluid outlet of the heat pump regenerator 16 is connected to the working fluid inlet of the heat pump charging expander 17; the working fluid outlet of the heat pump charging expander 17 is connected to the working fluid inlet of the working fluid-steam heat exchanger 18; the working fluid outlet of the working fluid-steam heat exchanger 18 is connected to the low-temperature working fluid inlet of the heat pump regenerator 16; the heat pump regenerator The low-temperature working fluid outlet of 16 is connected to the working fluid inlet of the heat pump charging compressor 14; the steam inlet of the molten salt preheater 19 is connected to the reheat steam outlet of the boiler 1, and the first valve 24 is connected to the pipeline between the reheat steam pipeline and the molten salt preheater 19; the steam outlet of the molten salt preheater 19 is connected to the steam inlet of the working fluid-steam heat exchanger 18; the steam outlet of the working fluid-steam heat exchanger 18 is connected to the steam inlet of the condenser 6; the molten salt outlet of the molten salt cold tank 11 is connected to the molten salt inlet of the molten salt preheater 19 through the 2# molten salt pump 20; the molten salt outlet of the molten salt preheater 19 is connected to the molten salt inlet of the molten salt-working fluid heat exchanger 15; the molten salt outlet of the molten salt-working fluid heat exchanger 15 is connected to the molten salt inlet of the molten salt hot tank 12; the heat pump charging compressor 14 and the heat pump charging expander 17 are connected to the motor 13 through the transmission shaft.

[0008] Furthermore, the molten salt cold tank 11 and the molten salt hot tank 12 use solar salt (60% NaNO3+40% KNO3) as heat storage medium, and the operating temperature range of the solar salt is 320-576°C; the temperature range of the reheated steam at the outlet of the molten salt preheater 19 is 340-345°C, and the temperature range of the molten salt at the outlet of the molten salt preheater 19 is 330-350°C.

[0009] Furthermore, the circulating working fluid used in the reheat steam coupled heat pump energy storage system is air, the circulation form adopts the Brayton cycle, the maximum outlet temperature of the heat pump charging compressor 14 is 586°C, and the minimum outlet temperature of the heat pump charging expander 17 is 30°C.

[0010] Furthermore, the heat pump charging compressor 14 is composed of at least a four-stage compressor, and adopts a centrifugal compressor, and the comprehensive inlet and outlet pressure ratio can reach 5.6.

[0011] Furthermore, the electric motor 13, the heat pump charging compressor 14 and the heat pump charging expander 17 are coaxially connected.

[0012] Furthermore, the molten salt cold tank 11 and the molten salt hot tank 12 each include an inlet and an outlet.

[0013] Furthermore, the reheat steam generator 10, the molten salt-working fluid heat exchanger 15, the working fluid-steam heat exchanger 18 and the molten salt preheater 19 all adopt shell and tube heat exchangers.

[0014] The operation method of the coal-fired power generation steam and heat pump integrated energy storage system,

[0015] 1) When the power consumption is low, the coal-fired unit coupled with the molten salt energy release system temporarily stops working, and most of the electric energy output by the coal-fired unit through the generator 5 is used as the input source of the motor 13 in the reheat steam coupled heat pump energy storage system. At the same time, part of the reheat steam of the coal-fired unit is used to heat the molten salt and the working fluid. The reheat steam coupled heat pump energy storage system is used to convert the electric energy of the coal-fired unit and part of the thermal energy of the reheat steam into the thermal energy of the molten salt for storage; specifically, close the second valve 25 on the branch of the high-pressure cylinder 2 exhaust pipe bypassing the reheat steam generator 10, stop the 1# molten salt pump 21, start the 2# molten salt pump 20, and open the first valve 24 on the branch of the reheat steam entering the molten salt preheater 19; in the reheat steam coupled heat pump energy storage system, the motor 13 drives the heat pump charging compressor 14 to work, and compresses the medium-temperature and low-pressure working fluid entering the heat pump charging compressor 14, and the high-temperature and high-pressure working fluid generated is converted into the molten salt-working fluid exchanger The heat exchanger 15 releases heat to the molten salt. The medium-temperature and high-pressure working fluid at the outlet of the molten salt-working fluid heat exchanger 15 releases heat in the heat pump regenerator 16 to produce a normal-temperature and high-pressure working fluid, and then enters the heat pump charging expander 17 to expand and do work. The low-temperature and low-pressure working fluid at the outlet of the heat pump charging expander 17 enters the working fluid-steam heat exchanger 18 to absorb heat to produce a normal-temperature and low-pressure working fluid, and then enters the heat pump regenerator 16 to absorb heat, and finally returns to the medium-temperature and low-pressure working fluid to enter the heat pump charging compressor 14; a part of the reheated steam at the outlet of the boiler 1 enters the molten salt preheater 19 and the working fluid-steam heat exchanger 18 in turn through the first valve 24 to release heat, and then returns to the condenser (6); the low-temperature molten salt in the molten salt cold tank 11 passes through the 2# molten salt pump 20, enters the molten salt preheater 19 and the molten salt-working fluid heat exchanger 15 in turn to absorb heat, and converts the excess electric energy of the coal-fired power generation unit and a part of the heat energy of the reheated steam into the heat energy of the molten salt, and finally stores it in the molten salt hot tank 12;

[0016] 2) When the power consumption is at its peak, the coal-fired unit is coupled with the molten salt energy release system to work normally, the second valve 25 on the branch of the high-pressure cylinder 2 exhaust pipe entering the reheat steam generator 10 is opened, the 1# molten salt pump 21 is started, the 2# molten salt pump 20 is stopped, and the first valve 24 on the branch of the reheat steam entering the molten salt preheater 19 is closed. At this time, the reheat steam of the coal-fired unit no longer enters the molten salt preheater 19; the high-temperature molten salt in the molten salt hot tank 12 enters the reheat steam generator 10 through the 1# molten salt pump 21 to release heat, and then returns to the molten salt cold tank 11. At the same time, the steam at the outlet of the high-pressure cylinder 2 enters the boiler 1 and the reheat steam generator 10 to absorb heat respectively. When the coal consumption of the boiler remains unchanged, the heat absorption of the main steam entering the boiler increases, and the main steam flow rate also increases, thereby increasing the output of the steam turbine and improving the output load of the coal-fired unit, and finally converting the thermal energy of the molten salt into the electrical energy output by the coal-fired generator set.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention integrates a high-temperature heat pump system into a coal-fired unit. While absorbing the output load of the coal-fired unit, it can also store and utilize the heat energy of the reheated steam to further reduce the output load of the coal-fired unit, thereby expanding the peak load regulation range of the coal-fired unit.

[0019] (2) The present invention introduces the design of a molten salt preheater in the heat storage process, and heats the molten salt before the reheated steam enters the heat pump system. Compared with the method of directly using the reheated steam in the heat pump system, the efficiency of the integrated energy storage system can be further improved;

[0020] (3) The present invention uses a solar salt as a heat storage medium. The working range of the molten salt has good consistency with the temperature range of the heat exchange process of steam and air, which can reduce the heat loss of the heat exchange process and thus improve the energy utilization efficiency of the integrated energy storage system;

[0021] (4) The present invention adopts a heat pump cycle heat storage method in the heat storage process. This heat storage method can utilize the heat of a low-temperature heat source and store it in a high-temperature heat source. Compared with the electric heating heat storage method, this heat storage method has higher energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a coal-fired power generation steam and heat pump integrated energy storage system of the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the preferred implementation examples described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0024] like Figure 1As shown, the present invention provides a coal-fired power generation steam and heat pump integrated energy storage system, including a coal-fired unit coupled with a molten salt energy release system and a reheat steam coupled with a heat pump energy storage system; wherein,

[0025] The coal-fired unit coupled molten salt energy release system includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a low-pressure heater 7, a deaerator 8, a high-pressure heater 9, a reheat steam generator 10, a molten salt cold tank 11, a molten salt hot tank 12, a 1# molten salt pump 21, a condensate pump 22 and a feed water pump 23; the main steam outlet of the boiler 1 is connected to the steam inlet of the high-pressure cylinder 2; the feed water inlet of the boiler 1 is connected to the feed water outlet of the high-pressure heater 9; the extraction steam outlet of the high-pressure cylinder 2 is connected to the steam inlet of the high-pressure heater 9 through a pipeline, and the steam outlet of the high-pressure cylinder 2 is respectively connected to the reheat steam inlet of the boiler 1 and the steam inlet of the reheat steam generator 10, and the second valve 25 is connected to the pipeline between the reheat steam generator 10 and the high-pressure cylinder 2; the steam inlet of the intermediate-pressure cylinder 3 is connected to the reheat steam outlet of the boiler 1 and the steam outlet of the reheat steam generator 10; the first-stage extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the steam inlet of the high-pressure reheater 9, and the second The steam extraction outlet of the first stage is connected to the steam inlet of the deaerator 8, and the steam outlet is connected to the steam inlets of the low-pressure cylinder 4 and the low-pressure heater 7 respectively; the drain outlet of the high-pressure heater 9 is connected to the drain inlet of the deaerator 8; the intermediate steam extraction outlet of the low-pressure cylinder 4 is connected to the steam inlet of the low-pressure heater 7, and the steam outlet is connected to the steam inlet of the condenser 6; the drain outlet of the low-pressure heater 7 is connected to the drain inlet of the condenser 6; the condensate outlet of the condenser 6 is connected to the low-pressure heater 7 through the condensate pump 22. The condensate inlet of the low-pressure heater 7 is connected; the condensate outlet of the low-pressure heater 7 is connected to the condensate inlet of the deaerator 8; the feed water outlet of the deaerator 8 is connected to the feed water inlet of the high-pressure reheater 9 through the feed water pump 23; the molten salt outlet of the molten salt hot tank 12 is connected to the molten salt inlet of the reheat steam generator 10 through the 1# molten salt pump 21; the molten salt outlet of the reheat steam generator 10 is connected to the molten salt inlet of the molten salt cold tank 11; the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 are connected to the generator 5 through the transmission shaft;

[0026] The reheat steam coupled heat pump energy storage system comprises a molten salt cold tank 11, a molten salt hot tank 12, an electric motor 13, a heat pump charging compressor 14, a molten salt-working fluid heat exchanger 15, a heat pump regenerator 16, a heat pump charging expander 17, a working fluid-steam heat exchanger 18, a molten salt preheater 19 and a 2# molten salt pump 20; the working fluid outlet of the heat pump charging compressor 14 is connected to the working fluid inlet of the molten salt-working fluid heat exchanger 15; the working fluid outlet of the molten salt-working fluid heat exchanger 15 is connected to the high-temperature working fluid inlet of the heat pump regenerator 16; the high-temperature working fluid outlet of the heat pump regenerator 16 is connected to the working fluid inlet of the heat pump charging expander 17; the working fluid outlet of the heat pump charging expander 17 is connected to the working fluid inlet of the working fluid-steam heat exchanger 18; the working fluid outlet of the working fluid-steam heat exchanger 18 is connected to the low-temperature working fluid inlet of the heat pump regenerator 16; the heat pump regenerator The low-temperature working fluid outlet of 16 is connected to the working fluid inlet of the heat pump charging compressor 14; the steam inlet of the molten salt preheater 19 is connected to the reheat steam outlet of the boiler 1, and the first valve 24 is connected to the pipeline between the reheat steam pipeline and the molten salt preheater 19; the steam outlet of the molten salt preheater 19 is connected to the steam inlet of the working fluid-steam heat exchanger 18; the steam outlet of the working fluid-steam heat exchanger 18 is connected to the steam inlet of the condenser 6; the molten salt outlet of the molten salt cold tank 11 is connected to the molten salt inlet of the molten salt preheater 19 through the 2# molten salt pump 20; the molten salt outlet of the molten salt preheater 19 is connected to the molten salt inlet of the molten salt-working fluid heat exchanger 15; the molten salt outlet of the molten salt-working fluid heat exchanger 15 is connected to the molten salt inlet of the molten salt hot tank 12; the heat pump charging compressor 14 and the heat pump charging expander 17 are connected to the motor 13 through the transmission shaft.

[0027] Furthermore, the molten salt cold tank 11 and the molten salt hot tank 12 use solar salt (60% NaNO3+40% KNO3) as the heat storage medium, and the operating temperature range of the solar salt is 320-576°C; the temperature range of the reheated steam at the outlet of the molten salt preheater 19 is 340-345°C, and the temperature range of the molten salt at the outlet of the molten salt preheater 19 is 330-350°C. This expands the working medium operating range, can utilize higher-grade energy, and ensure the high efficiency of the energy storage system.

[0028] Furthermore, the circulating working fluid used in the reheat steam coupled heat pump energy storage system is air, the circulation form adopts the Brayton cycle, the maximum outlet temperature of the heat pump charging compressor 14 is 586°C, and the minimum outlet temperature of the heat pump charging expander 17 is 30°C. In this way, the temperature range of heat exchange between air and other working fluids can be fully matched, the irreversible loss of the system can be reduced, and the safety and efficiency of the system can be ensured.

[0029] Furthermore, the heat pump charging compressor 14 is composed of at least four-stage compressors, and adopts a centrifugal compressor, and the inlet and outlet comprehensive pressure ratio can reach 5.6. This can reduce the investment in steam turbine equipment, reduce investment costs, and ensure the economy of the system.

[0030] Further, the motor 13, the heat pump charging compressor 14 and the heat pump charging expander 17 are coaxially connected. This can ensure that the equipment runs at the same frequency and reduce unnecessary losses.

[0031] Furthermore, the molten salt cold tank 11 and the molten salt hot tank 12 include an inlet and an outlet.

[0032] Furthermore, the reheat steam generator 10, the molten salt-working medium heat exchanger 15, the working medium-steam heat exchanger 18 and the molten salt preheater 19 all adopt shell and tube heat exchangers, which can ensure the high efficiency of the heat exchange process and facilitate the maintenance of the equipment.

[0033] The operation method of the coal-fired power generation steam and heat pump integrated energy storage system,

[0034] 1) When the power consumption is low, the coal-fired unit coupled with the molten salt energy release system temporarily stops working, and most of the electric energy output by the coal-fired unit through the generator 5 is used as the input source of the motor 13 in the reheat steam coupled heat pump energy storage system. At the same time, part of the reheat steam of the coal-fired unit is used to heat the molten salt and the working fluid. The reheat steam coupled heat pump energy storage system is used to convert the electric energy of the coal-fired unit and part of the thermal energy of the reheat steam into the thermal energy of the molten salt for storage; specifically, close the second valve 25 on the branch of the high-pressure cylinder 2 exhaust pipe bypassing the reheat steam generator 10, stop the 1# molten salt pump 21, start the 2# molten salt pump 20, and open the first valve 24 on the branch of the reheat steam entering the molten salt preheater 19; in the reheat steam coupled heat pump energy storage system, the motor 13 drives the heat pump charging compressor 14 to work, and compresses the medium-temperature and low-pressure working fluid entering the heat pump charging compressor 14, and the high-temperature and high-pressure working fluid generated passes through the molten salt-working fluid The heat exchanger 15 releases heat to the molten salt. The medium-temperature and high-pressure working fluid at the outlet of the molten salt-working fluid heat exchanger 15 releases heat in the heat pump regenerator 16 to produce a normal-temperature and high-pressure working fluid, and then enters the heat pump charging expander 17 to expand and do work. The low-temperature and low-pressure working fluid at the outlet of the heat pump charging expander 17 enters the working fluid-steam heat exchanger 18 to absorb heat to produce a normal-temperature and low-pressure working fluid, and then enters the heat pump regenerator 16 to absorb heat, and finally returns to the medium-temperature and low-pressure working fluid to enter the heat pump charging compressor 14; a part of the reheated steam at the outlet of the boiler 1 passes through the first valve 24 to enter the molten salt preheater 19 and the working fluid-steam heat exchanger 18 in turn to release heat, and then returns to the condenser 6; the low-temperature molten salt in the molten salt cold tank 11 passes through the 2# molten salt pump 20, and enters the molten salt preheater 19 and the molten salt-working fluid heat exchanger 15 in turn to absorb heat, and converts the excess electric energy of the coal-fired power generation unit and a part of the thermal energy of the reheated steam into the thermal energy of the molten salt, and finally stores it in the molten salt hot tank 12;

[0035] 2) When the power consumption is at its peak, the coal-fired unit is coupled with the molten salt energy release system to work normally, the second valve 25 on the branch of the high-pressure cylinder 2 exhaust pipe entering the reheat steam generator 10 is opened, the 1# molten salt pump 21 is started, the 2# molten salt pump 20 is stopped, and the first valve 24 on the branch of the reheat steam entering the molten salt preheater 19 is closed. At this time, the reheat steam of the coal-fired unit no longer enters the molten salt preheater 19; the high-temperature molten salt in the molten salt hot tank 12 enters the reheat steam generator 10 through the 1# molten salt pump 21 to release heat, and then returns to the molten salt cold tank 11. At the same time, the steam at the outlet of the high-pressure cylinder 2 enters the boiler 1 and the reheat steam generator 10 to absorb heat respectively. When the coal consumption of the boiler remains unchanged, the heat absorption of the main steam entering the boiler increases, and the main steam flow rate also increases, thereby increasing the output of the steam turbine and improving the output load of the coal-fired unit, and finally converting the thermal energy of the molten salt into the electrical energy output by the coal-fired generator set.

[0036] When the power consumption is low, the system of the present invention outputs electric energy to drive the heat pump charging compressor to compress the heat pump working fluid, and then the heat pump working fluid heats the molten salt. At the same time, a part of the reheated steam of the coal-fired unit heats the molten salt and the heat pump charging expander outlet working fluid in turn, further reducing the load, and finally converting the excess electric energy and a part of the heat energy of the reheated steam into molten salt heat energy for storage; when the power consumption is peak, a part of the high-pressure cylinder exhaust steam is heated with the heat stored in the molten salt storage tank to generate reheated steam, and the main steam entering the boiler absorbs more heat when the boiler coal consumption remains unchanged, and the main steam flow rate also increases, thereby increasing the output load of the coal-fired unit. The system of the present invention can give full play to the peak-shaving potential of coal-fired generator sets, expand the output load range of the unit, and is an effective method to improve the peak-shaving capacity of coal-fired units and smooth out power grid fluctuations.

Claims

1. A coal-fired power generation steam and heat pump integrated energy storage system, characterized in that: It includes a coal-fired unit coupled molten salt energy release system and a reheat steam coupled heat pump energy storage system; among which, The coal-fired unit coupled molten salt energy release system comprises a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a generator (5), a condenser (6), a low-pressure heater (7), a deaerator (8), a high-pressure heater (9), a reheat steam generator (10), a molten salt cold tank (11), a molten salt hot tank (12), a 1# molten salt pump (21), a condensate pump (22) and a feed water pump (23); the main steam outlet of the boiler (1) is connected to the steam inlet of the high-pressure cylinder (2); the feed water inlet of the boiler (1) is connected to the feed water outlet of the high-pressure heater (9) The steam extraction outlet of the high-pressure cylinder (2) is connected to the steam inlet of the high-pressure heater (9) through a pipeline, the steam outlet of the high-pressure cylinder (2) is respectively connected to the reheat steam inlet of the boiler (1) and the steam inlet of the reheat steam generator (10), and the second valve (25) is connected to the pipeline between the reheat steam generator (10) and the high-pressure cylinder (2); the steam inlet of the intermediate-pressure cylinder (3) is connected to the reheat steam outlet of the boiler (1) and the steam outlet of the reheat steam generator (10); the first-stage steam extraction outlet of the intermediate-pressure cylinder (3) is connected to the steam inlet of the high-pressure reheater (9) The second-stage steam extraction outlet is connected to the steam inlet of the deaerator (8), and the steam outlet is respectively connected to the steam inlets of the low-pressure cylinder (4) and the low-pressure heater (7); the drain outlet of the high-pressure heater (9) is connected to the drain inlet of the deaerator (8); the intermediate steam extraction outlet of the low-pressure cylinder (4) is connected to the steam inlet of the low-pressure heater (7), and the steam outlet is connected to the steam inlet of the condenser (6); the drain outlet of the low-pressure heater (7) is connected to the drain inlet of the condenser (6); the condensate outlet of the condenser (6) is connected to the low-pressure heater ( 7); the condensate outlet of the low-pressure heater (7) is connected to the condensate inlet of the deaerator (8); the feed water outlet of the deaerator (8) is connected to the feed water inlet of the high-pressure reheater (9) through the feed water pump (23); the molten salt outlet of the molten salt hot tank (12) is connected to the molten salt inlet of the reheat steam generator (10) through the 1# molten salt pump (21); the molten salt outlet of the reheat steam generator (10) is connected to the molten salt inlet of the molten salt cold tank (11); the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) are connected to the generator (5) through the transmission shaft; The reheat steam coupled heat pump energy storage system comprises a molten salt cold tank (11), a molten salt hot tank (12), an electric motor (13), a heat pump charging compressor (14), a molten salt-working fluid heat exchanger (15), a heat pump regenerator (16), a heat pump charging expander (17), a working fluid-steam heat exchanger (18), a molten salt preheater (19) and a second molten salt pump (20); the working fluid outlet of the heat pump charging compressor (14) and the working fluid inlet of the molten salt-working fluid heat exchanger (15) are connected to each other. The working fluid outlet of the molten salt-working fluid heat exchanger (15) is connected to the high-temperature working fluid inlet of the heat pump regenerator (16); the high-temperature working fluid outlet of the heat pump regenerator (16) is connected to the working fluid inlet of the heat pump charging expander (17); the working fluid outlet of the heat pump charging expander (17) is connected to the working fluid inlet of the working fluid-steam heat exchanger (18); the working fluid outlet of the working fluid-steam heat exchanger (18) is connected to the low-temperature working fluid inlet of the heat pump regenerator (16); the heat pump regenerator The low-temperature working medium outlet of the heat pump (16) is connected to the working medium inlet of the heat pump charging compressor (14); the steam inlet of the molten salt preheater (19) is connected to the reheat steam outlet of the boiler (1), and the first valve (24) is connected to the pipeline between the reheat steam pipeline and the molten salt preheater (19); the steam outlet of the molten salt preheater (19) is connected to the steam inlet of the working medium-steam heat exchanger (18); the steam outlet of the working medium-steam heat exchanger (18) is connected to the steam outlet of the condenser (6); The molten salt outlet of the molten salt cold tank (11) is connected to the molten salt inlet of the molten salt preheater (19) through the 2# molten salt pump (20); the molten salt outlet of the molten salt preheater (19) is connected to the molten salt inlet of the molten salt-working fluid heat exchanger (15); the molten salt outlet of the molten salt-working fluid heat exchanger (15) is connected to the molten salt inlet of the molten salt hot tank (12); the heat pump charging compressor (14) and the heat pump charging expander (17) are connected to the motor (13) through a transmission shaft.

2. A coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The molten salt cold tank (11) and the molten salt hot tank (12) use solar salt, i.e. 60% NaNO3+40% KNO3, as the heat storage medium, and the operating temperature range of the solar salt is 320-576°C; the temperature range of the reheated steam at the outlet of the molten salt preheater (19) is 340-345°C, and the temperature range of the molten salt at the outlet of the molten salt preheater (19) is 330-350°C.

3. A coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The circulating working fluid used in the reheat steam coupled heat pump energy storage system is air, the circulation form adopts the Brayton cycle, the maximum outlet temperature of the heat pump charging compressor (14) is 586°C, and the minimum outlet temperature of the heat pump charging expander (17) is 30°C.

4. A coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The heat pump charging compressor (14) is composed of at least four-stage compressors and adopts a centrifugal compressor, and the inlet and outlet comprehensive pressure ratio reaches 5.

6.

5. The coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The electric motor (13), the heat pump charging compressor (14) and the heat pump charging expander (17) are coaxially connected.

6. The coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The molten salt cold tank (11) and the molten salt hot tank (12) each include an inlet and an outlet.

7. The coal-fired power generation steam and heat pump integrated energy storage system according to claim 1, characterized in that: The reheat steam generator (10), the molten salt-working fluid heat exchanger (15), the working fluid-steam heat exchanger (18) and the molten salt preheater (19) all adopt shell and tube heat exchangers.

8. The method for operating a coal-fired power generation steam and heat pump integrated energy storage system according to any one of claims 1 to 7, characterized in that: 1) When the power consumption is low, the coal-fired unit coupled with the molten salt energy release system temporarily stops working, and most of the electric energy output by the coal-fired unit through the generator (5) is used as the input source of the motor (13) in the reheat steam coupled heat pump energy storage system. At the same time, part of the reheat steam of the coal-fired unit is used to heat the molten salt and the working medium. The reheat steam coupled heat pump energy storage system is used to convert the electric energy of the coal-fired unit and part of the thermal energy of the reheat steam into the thermal energy of the molten salt for storage; specifically, the high-pressure cylinder (2) is closed by the exhaust pipe The second valve (25) on the branch line of the reheat steam generator (10) is opened, the 1# molten salt pump (21) is stopped, the 2# molten salt pump (20) is started, and the first valve (24) on the branch line of the reheat steam entering the molten salt preheater (19) is opened; the motor (13) in the reheat steam coupled heat pump energy storage system drives the heat pump charging compressor (14) to work, compresses the medium-temperature and low-pressure working fluid entering the heat pump charging compressor (14), and the high-temperature and high-pressure working fluid generated passes through the molten salt-working fluid heat exchanger (15 ) releases heat to the molten salt, the medium-temperature and high-pressure working fluid at the outlet of the molten salt-working fluid heat exchanger (15) releases heat in the heat pump regenerator (16) to produce a normal-temperature and high-pressure working fluid, and then enters the heat pump charging expander (17) to expand and do work, the low-temperature and low-pressure working fluid at the outlet of the heat pump charging expander (17) enters the working fluid-steam heat exchanger (18) to absorb heat to produce a normal-temperature and low-pressure working fluid, and then enters the heat pump regenerator (16) to absorb heat, and finally returns to the medium-temperature and low-pressure working fluid to enter the heat pump charging compressor (14); boiler (1) A portion of the reheated steam at the outlet enters the molten salt preheater (19) and the working medium-steam heat exchanger (18) in sequence through the first valve (24) to release heat, and then returns to the condenser (6); the low-temperature molten salt in the molten salt cold tank (11) passes through the No. 2 molten salt pump (20), and enters the molten salt preheater (19) and the molten salt-working medium heat exchanger (15) in sequence to absorb heat, converting the excess electric energy of the coal-fired power generation unit and a portion of the heat energy of the reheated steam into the heat energy of the molten salt, which is finally stored in the molten salt hot tank (12); 2) When the power consumption is at a peak, the coal-fired unit is coupled with the molten salt energy release system to work normally, the second valve (25) on the branch of the high-pressure cylinder (2) exhaust pipe entering the reheat steam generator (10) is opened, the No. 1 molten salt pump (21) is started, the No. 2 molten salt pump (20) is stopped, and the first valve (24) on the branch of the reheat steam entering the molten salt preheater (19) is closed. At this time, the reheat steam of the coal-fired unit no longer enters the molten salt preheater (19); the high-temperature molten salt in the molten salt hot tank (12) enters the reheat steam generator (10) through the No. 1 molten salt pump (21) to release heat, and then returns to the molten salt cold tank (11). At the same time, the steam at the outlet of the high-pressure cylinder (2) enters the boiler (1) and the reheat steam generator (10) respectively to absorb heat. When the coal consumption of the boiler remains unchanged, the heat absorption of the main steam entering the boiler increases, and the main steam flow rate also increases, thereby increasing the output of the steam turbine and improving the output load of the coal-fired unit, and finally converting the thermal energy of the molten salt into the electrical energy output by the coal-fired generator set.

Images