Double-medium heat storage type gas-steam combined cycle combined heat and power generation unit

Abstract

The invention discloses a double-medium heat storage type gas-steam combined cycle combined heat and power generation unit which comprises a gas turbine power generation system, a waste heat boiler system, a steam turbine power generation system, a flue gas bypass baffle, a fused salt heat storage system, a water heat storage system, a heat storage water feeding pump and the like. In the off-peak period of power utilization of a power grid, the double-medium energy storage system firstly stores exhaust heat of a gas turbine, the effect that a steam turbine is reduced to the minimum load and even stops running is achieved, then residual on-grid electric quantity heat of a unit is stored, and the double-medium energy storage system releases heat and generates steam to supply industrial steam extraction of the unit while storing heat; in the peak period of power utilization of the power grid, the double-medium energy storage system releases heat and generates steam to supply industrial steam extraction of the unit and extrudes steam extraction of the original unit, and the original steam turbine generates power at the peak. A flexible and efficient combined heat and power generation mode is provided, the problems that a gas-steam combined cycle combined heat and power generation unit is low in heat supply energy efficiency and serious in loss in the power utilization trough period of a power grid are solved, and the operation flexibility of the unit is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of cogeneration, and in particular relates to a dual-medium heat storage type gas-steam combined cycle cogeneration unit. Background Art

[0002] At present, the gas-steam combined cycle cogeneration units operate in a "heat-based electricity" mode, and the operation mode is not flexible. In order to maintain the external heat load demand, the unit's power generation load has to be maintained at a high level. However, based on the current status of the electricity spot market, during the low-power period of the power grid, the on-grid electricity price is inverted or even negative. The on-grid electricity volume that has to be maintained at a high level will cause serious losses. In order to reduce losses, the unit generally chooses to shut down, and then uses a standby gas boiler for heating or electric heating to meet the unit's heat load demand, but these heating methods also have the problem of low energy efficiency. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a dual-medium heat storage type gas-steam combined cycle cogeneration unit, which is composed of an original gas-steam combined cycle cogeneration unit coupled with a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system, including a gas turbine power generation system, a waste heat boiler system, a steam turbine power generation system, a flue gas bypass baffle, a molten salt heat storage system, a water heat storage system, a heat storage feed water pump and other equipment; the molten salt heat storage system in the dual-medium energy storage system can be divided into two levels according to the nature of the heat storage heat source, the first level is a flue gas heating molten salt heat storage system, and the second level is an electric heating molten salt heat storage system, and the two-stage molten salt heat storage systems are arranged in parallel. During the off-peak period of power grid, the first-level flue gas heating molten salt heat storage system and the water heat storage system first store the heat of the gas turbine exhaust to reduce the steam turbine to the minimum load or even shut down, and then the second-level electric heating molten salt heat storage system stores the heat of the remaining online power of the unit, and the dual-medium energy storage system releases heat and produces steam to supply the industrial steam extraction of the unit while storing heat; during the peak period of power grid, the dual-medium energy storage system releases heat and produces steam to supply the industrial steam extraction of the unit while displacing the original unit's steam extraction, and the original steam turbine generates electricity at its peak. The present invention provides a flexible and efficient cogeneration mode, which solves the problem of low heating efficiency and serious losses of gas-steam combined cycle cogeneration units during the off-peak period of power grid, and improves the flexibility of unit operation.

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

[0005] A dual-medium heat storage type gas-steam combined cycle cogeneration unit, which is composed of an original gas-steam combined cycle cogeneration unit coupled with a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system; the molten salt heat storage system is divided into two levels according to the nature of the heat storage heat source, the first level is a flue gas heating molten salt heat storage system, and the second level is an electric heating molten salt heat storage system, and the flue gas heating molten salt heat storage system and the electric heating molten salt heat storage system are arranged in parallel; the flue gas heating molten salt heat storage system and the water heat storage system of the first level are arranged in series and then in parallel with the waste heat boiler system of the original gas-steam combined cycle cogeneration unit; by adjusting the opening of the flue gas bypass damper of the original gas-steam combined cycle cogeneration unit, the exhaust gas of the gas turbine of the original gas-steam combined cycle cogeneration unit is controlled to enter the waste heat boiler The gas volume of the boiler bypass flue, the first-level flue gas heating molten salt heat storage system is responsible for storing the high-grade heat of the gas turbine exhaust through the gas-salt heat exchanger of the molten salt heat storage system, and the water heat storage system is responsible for storing the low-grade heat of the gas turbine exhaust through the second medium-pressure economizer of the water heat storage system, so that after the steam turbine is reduced to the minimum load or the steam turbine stops running, the second-level electric heating molten salt heat storage system is responsible for storing the heat of the remaining online power of the unit through the molten salt electric heater of the molten salt heat storage system. The high-grade heat is stored in the molten salt heat storage tank, and the low-grade heat is stored in the water storage tank. The stored heat is used to heat the feed water from the heat storage feed water pump, and then the feed water flows through the phase change heat exchanger of the molten salt heat storage system to evaporate into steam, and the steam then flows through the steam-salt heat exchanger of the molten salt heat storage system to generate superheated steam to supply the unit's thermal load.

[0006] Furthermore, the original gas-steam combined cycle cogeneration unit includes a compressor, a combustion chamber, a gas turbine, a gas turbine generator, a steam turbine high-pressure cylinder, a steam turbine medium-pressure cylinder, a steam turbine low-pressure cylinder, a steam turbine generator, a condenser, a condensate pump, a low-pressure economizer, a low-pressure evaporator, a low-pressure superheater, a medium-pressure feed water pump, a medium-pressure economizer, a medium-pressure evaporator, a medium-pressure superheater, a reheater, a high-pressure feed water pump, a high-pressure economizer, a high-pressure evaporator, a high-pressure superheater, a flue gas bypass baffle, and a chimney.

[0007] Furthermore, the exhaust duct of the gas turbine is divided into two paths, one path enters the waste heat boiler flue, and the other path enters the waste heat boiler bypass flue. The flue gas bypass damper is installed at the entrance of the waste heat boiler flue and the waste heat boiler bypass flue, and plays the role of a three-way to control the exhaust gas of the gas turbine to flow to the waste heat boiler flue or the waste heat boiler bypass flue. When the flue gas bypass damper is fully opened, the exhaust gas of the gas turbine all enters the waste heat boiler flue. When the flue gas bypass damper is fully closed, the exhaust gas of the gas turbine all enters the waste heat boiler bypass flue. By adjusting the opening of the flue gas bypass damper, the exhaust volume ratio of the gas turbine exhaust entering the waste heat boiler flue and the waste heat boiler bypass flue is controlled.

[0008] Furthermore, the molten salt heat storage system includes a gas-salt heat exchanger, a molten salt electric heater, a low-temperature molten salt tank, a low-temperature molten salt pump, a high-temperature molten salt tank, a high-temperature molten salt pump, a phase change heat exchanger level control valve, a water-salt heat exchanger, a phase change heat exchanger, a steam-salt heat exchanger, a gas-salt heat storage control valve, and an electric heat storage control valve, wherein the gas-salt heat exchanger and the molten salt electric heater are arranged in parallel; the water heat storage system includes a second medium-pressure economizer, a cold water tank level control valve, a cold water tank, a cold water pump, a hot water tank, and a hot water pump.

[0009] Furthermore, during the period of low power consumption in the power grid, the dual-medium energy storage system will release the heat stored in the molten salt and water while storing heat, heat the feed water to generate steam to supply the thermal load of the unit, and operate in a "storage and release" mode; during the period of peak power consumption in the power grid, the dual-medium energy storage system will release the heat stored in the high-temperature molten salt tank and the hot water in the hot water tank, heat the feed water to generate steam, supply the industrial extraction steam of the unit, and at the same time squeeze out the original unit extraction steam, and the original steam turbine will generate peak power.

[0010] Furthermore, a gas-salt heat exchanger and a second medium-pressure economizer are sequentially arranged inside the bypass flue of the waste heat boiler along the exhaust direction of the gas turbine; the outlet of the low-temperature molten salt tank is connected to the inlet of the low-temperature molten salt pump through a pipeline, and the outlet of the low-temperature molten salt pump is divided into two paths, one of which is connected to the inlet of the gas-salt heat storage control valve through a pipeline, and the outlet of the gas-salt heat storage control valve is connected to the inlet of the gas-salt heat exchanger, and the outlet of the gas-salt heat exchanger is connected to the inlet of the high-temperature molten salt tank, and the other outlet of the low-temperature molten salt pump is connected to the inlet of the electric heat storage control valve through a pipeline, and the outlet of the electric heat storage control valve is connected to the inlet of the molten salt electric heater, and the outlet of the molten salt electric heater is also connected to the inlet of the high-temperature molten salt tank, and the gas-salt heat exchanger and the molten salt electric heater are arranged in parallel; the outlet of the high-temperature molten salt tank is connected to the inlet of the high-temperature molten salt pump by a pipeline, and the outlet of the high-temperature molten salt pump is sequentially connected to the steam-salt heat exchanger, the phase change heat exchanger, and the phase change heat exchanger. and water-salt heat exchanger, and finally connected to the inlet of the low-temperature molten salt tank; another way of the condensed water at the outlet of the condenser is connected to the inlet of the heat storage feed water pump through a pipeline, the outlet of the heat storage feed water pump is divided into two ways, one way is connected to the inlet of the cold water tank level control valve, the outlet of the cold water tank level control valve is connected to the inlet of the cold water tank, the outlet of the cold water tank is connected to the inlet of the cold water pump, the outlet of the cold water pump is connected to the inlet of the second medium-pressure economizer, the outlet of the second medium-pressure economizer is connected to the inlet of the hot water tank, the outlet of the hot water tank is connected to the inlet of the hot water pump, the other way of the outlet of the heat storage feed water pump is connected to the inlet of the phase change heat exchanger level control valve, after the outlet of the phase change heat exchanger level control valve and the outlet pipeline of the hot water pump are merged, they are sequentially connected to the water-salt heat exchanger and the phase change heat exchanger, and finally connected to the inlet of the steam-salt heat exchanger, and the outlet of the steam-salt heat exchanger is connected to the heating pipeline of the intermediate-pressure cylinder of the steam turbine.

[0011] Furthermore, according to the heat storage requirements of the molten salt heat storage system, the gas-salt heat exchanger is single-stage or multi-stage.

[0012] Furthermore, the unit's heating extraction steam is extracted from the turbine intermediate pressure cylinder. According to the pressure and temperature of the actual heating heat load, the extraction position and the number of extraction ports in the turbine high pressure cylinder, turbine intermediate pressure cylinder and turbine low pressure cylinder can be adjusted.

[0013] Furthermore, during the off-peak period of the power grid, the flue gas bypass damper is fully opened, and the exhaust gas of the gas turbine passes through the flue gas bypass damper and flows along the waste heat boiler flue in sequence through the reheater, high-pressure superheater, high-pressure evaporator, high-pressure economizer, medium-pressure superheater, medium-pressure evaporator, medium-pressure economizer, low-pressure superheater, low-pressure evaporator and low-pressure economizer, and finally enters the chimney. At this time, the dual-medium energy storage system is not put into operation; during the off-peak period of the power grid, the gas turbine is kept running, and the opening of the flue gas bypass damper is adjusted to control the exhaust gas of part or all of the gas turbines to flow along the waste heat boiler bypass flue in sequence through the gas-salt heat exchanger and the second medium-pressure economizer, and finally enter the chimney. At the same time, the condensate from the outlet of the condenser is boosted by the heat storage feed water pump and then controlled by the cold water tank liquid level control system. The valve controls the water level of the cold water tank. The outlet water of the cold water tank is pressurized by the cold water pump and enters the second medium-pressure economizer for reverse heat exchange with the gas turbine exhaust. The hot water after heat exchange flows to the hot water tank. At the same time, the low-temperature molten salt at the outlet of the low-temperature molten salt tank is pressurized by the low-temperature molten salt pump and is divided into two paths. One path first flows through the gas-salt heat storage control valve, then flows through the gas-salt heat exchanger for reverse heat exchange with the gas turbine exhaust, and finally flows to the high-temperature molten salt tank; after the steam turbine is reduced to the minimum load or shut down, the other path of low-temperature molten salt first flows through the electric heat storage control valve, and then flows through the molten salt electric heater. The molten salt heat storage is heated by reducing the total online power of the gas turbine generator and the steam turbine generator to zero. The heated hot molten salt also flows to the high-temperature molten salt tank, realizing the heat storage of the dual-medium energy storage system.

[0014] Furthermore, the hot water stored in the hot water tank is pressurized by the hot water pump and becomes high-pressure hot water. The high-pressure hot water is mixed with the condensed water from the condenser, the heat storage feed water pump and the phase change heat exchanger level control valve and releases heat. This process realizes the heat release of the heat storage hot water; the high-temperature molten salt stored in the high-temperature molten salt tank is pressurized by the high-temperature molten salt pump and flows through the steam-salt heat exchanger, the phase change heat exchanger and the water-salt heat exchanger in sequence. The low-temperature molten salt after releasing heat flows into the low-temperature molten salt tank. This molten salt process realizes the heat release process of the molten salt; the condensed water from the phase change heat exchanger level control valve and the hot water from the hot water pump are mixed and heated, and then flow through the water-salt heat exchanger for preheating. The preheated water flows through the phase change heat exchanger to evaporate into steam, and the steam flows through the steam-salt heat exchanger for superheating, realizing the steam absorption process. The generated superheated steam is combined with the heating extraction steam of the intermediate pressure cylinder of the turbine to realize the heat release of the dual-medium energy storage system.

[0015] The present invention realizes the "thermal and electric decoupling" of the original cogeneration unit by coupling a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system, thereby ensuring the flexible operation of the unit while ensuring the industrial heat load of the unit.

[0016] Beneficial effects:

[0017] The present invention provides a flexible and efficient cogeneration mode for the original cogeneration unit, thereby improving the operation flexibility of the unit. During the period of average power consumption in the power grid, the dual-medium energy storage system is not put into operation, and the unit extracts steam and generates electricity according to the original operation mode; during the period of low power consumption in the power grid, the gas turbine is kept in operation, and the exhaust volume entering the bypass flue of the waste heat boiler is flexibly adjusted by adjusting the opening of the flue gas bypass damper. The first-level flue gas heating molten salt heat storage system and the water heat storage system store part or all of the exhaust heat of the gas turbine, so that after the steam turbine is reduced to the minimum load or shut down, the second-level electric heating molten salt heat storage system reduces the unit's online power to zero through the molten salt electric heater to heat the molten salt heat storage. While storing energy, the system also releases the heat stored in the molten salt and water to ensure the heating demand of the unit, heat the feed water to generate high-temperature steam to supply the unit's thermal load, thereby minimizing losses while ensuring the heating of the unit; during the peak power consumption period of the power grid, the dual-medium energy storage system releases the heat stored in the molten salt and water, heats the feed water to generate high-temperature steam, supplies the unit with industrial extraction steam, and squeezes out the original unit extraction steam, and the original steam turbine generates electricity at the peak, participating in the peak load regulation of the power grid while earning "low storage and high release" benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a dual-medium heat storage type gas-steam combined cycle cogeneration unit of the present invention.

[0019] In the figure, the reference numerals are: 1 compressor, 2 combustion chamber, 3 gas turbine, 4 gas turbine generator, 5 turbine high pressure cylinder, 6 turbine medium pressure cylinder, 7 turbine low pressure cylinder, 8 turbine generator, 9 condenser, 10 condensate pump, 11 low pressure economizer, 12 low pressure evaporator, 13 low pressure superheater, 14 medium pressure feed water pump, 15 medium pressure economizer, 16 medium pressure evaporator, 17 medium pressure superheater, 18 reheater, 19 high pressure feed water pump, 20 high pressure economizer, 21 high pressure evaporator, 22 high pressure superheater, 23 Chimney, 24 flue gas bypass baffle, 26 gas-salt heat exchanger, 27 second medium-pressure economizer, 28 molten salt electric heater, 29 low-temperature molten salt tank, 30 low-temperature molten salt pump, 31 high-temperature molten salt tank, 32 high-temperature molten salt pump, 33 heat storage feed water pump, 34 cold water tank level control valve, 35 cold water tank, 36 cold water pump, 37 hot water tank, 38 hot water pump, 39 phase change heat exchanger level control valve, 40 water-salt heat exchanger, 41 phase change heat exchanger, 42 steam-salt heat exchanger, 43 gas-salt heat storage control valve, 44 electric heat storage control valve. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] Example 1

[0022] like Figure 1 As shown, a dual-medium heat storage type gas-steam combined cycle cogeneration unit of the present invention comprises a compressor 1, a combustion chamber 2, a gas turbine 3, a gas turbine generator 4, a steam turbine high-pressure cylinder 5, a steam turbine medium-pressure cylinder 6, a steam turbine low-pressure cylinder 7, a steam turbine generator 8, a condenser 9, a condensate pump 10, a low-pressure economizer 11, a low-pressure evaporator 12, a low-pressure superheater 13, a medium-pressure feed water pump 14, a medium-pressure economizer 15, a medium-pressure evaporator 16, a medium-pressure superheater 17, a reheater 18, a high-pressure feed water pump 19, a high-pressure economizer 20, a high-pressure evaporator 21, a high-pressure superheater 22, and a flue gas bypass baffle 23. , chimney 24, gas-salt heat exchanger 26, second medium-pressure economizer 27, molten salt electric heater 28, low-temperature molten salt tank 29, low-temperature molten salt pump 30, high-temperature molten salt tank 31, high-temperature molten salt pump 32, heat storage water pump 33, cold water tank level control valve 34, cold water tank 35, cold water pump 36, hot water tank 37, hot water pump 38, phase change heat exchanger level control valve 39, water-salt heat exchanger 40, phase change heat exchanger 41, steam-salt heat exchanger 42, gas-salt heat storage control valve 43, electric heat storage control valve 44 as well as pipelines, other valves and accessories; the accessories include sensors, transmitters, controllers and actuators, etc.

[0023] The present invention is composed of an original gas-steam combined cycle heat and power cogeneration unit coupled with a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system.

[0024] The original gas-steam combined cycle cogeneration unit includes a compressor 1, a combustion chamber 2, a gas turbine 3, a gas turbine generator 4, a steam turbine high-pressure cylinder 5, a steam turbine medium-pressure cylinder 6, a steam turbine low-pressure cylinder 7, a steam turbine generator 8, a condenser 9, a condensate pump 10, a low-pressure economizer 11, a low-pressure evaporator 12, a low-pressure superheater 13, a medium-pressure feed water pump 14, a medium-pressure economizer 15, a medium-pressure evaporator 16, a medium-pressure superheater 17, a reheater 18, a high-pressure feed water pump 19, a high-pressure economizer 20, a high-pressure evaporator 21, a high-pressure superheater 22, a flue gas bypass baffle 23, and a chimney 24.

[0025] The molten salt heat storage system can be divided into two levels according to the properties of the heat storage heat source. The first level is a flue gas heating molten salt heat storage system, and the second level is an electric heating molten salt heat storage system. The flue gas heating molten salt heat storage system and the electric heating molten salt heat storage system are arranged in parallel.

[0026] The molten salt heat storage system includes a gas-salt heat exchanger 26, a molten salt electric heater 28, a low-temperature molten salt tank 29, a low-temperature molten salt pump 30, a high-temperature molten salt tank 31, a high-temperature molten salt pump 32, a phase change heat exchanger level control valve 39, a water-salt heat exchanger 40, a phase change heat exchanger 41, a steam-salt heat exchanger 42, a gas-salt heat storage control valve 43, and an electric heat storage control valve 44, wherein the gas-salt heat exchanger 26 and the molten salt electric heater 28 are arranged in parallel.

[0027] The water heat storage system includes a second medium-pressure economizer 27 , a cold water tank level control valve 34 , a cold water tank 35 , a cold water pump 36 , a hot water tank 37 , and a hot water pump 38 .

[0028] In addition to the molten salt heat storage system and the water heat storage system, the dual-medium energy storage system also includes their common equipment - a heat storage water pump 33.

[0029] The compressor 1 is connected to the air inlet of the combustion chamber 2 through an air duct, and the outlet of the combustion chamber 2 is connected to the inlet of the gas turbine 3. The gas turbine 3 is coaxially arranged with the gas generator 4 through a rigid coupling and connected by a rigid coupling. The exhaust duct of the gas turbine 3 is divided into two paths, one of which is connected to the inlet of the waste heat boiler flue, and the other is connected to the inlet of the waste heat boiler bypass flue. The inlets of the waste heat boiler flue and the waste heat boiler bypass flue are equipped with flue gas bypass baffles 23. The outlets of the waste heat boiler flue and the waste heat boiler bypass flue are both connected to the chimney 24. The interior of the waste heat boiler flue is arranged in sequence along the exhaust direction of the gas turbine 3, including a reheater 18, a high-pressure superheater 22, a high-pressure evaporator 21, a high-pressure economizer 20, a medium-pressure superheater 17, a medium-pressure evaporator 16, A medium-pressure economizer 15, a low-pressure superheater 13, a low-pressure evaporator 12 and a low-pressure economizer 11, a gas-salt heat exchanger 26 and a second medium-pressure economizer 27 are arranged in sequence inside the waste heat boiler bypass flue along the exhaust direction of the gas turbine 3; the outlet of the high-pressure superheater 22 is connected to the inlet of the high-pressure cylinder 5 of the steam turbine, the outlet of the high-pressure cylinder 5 of the steam turbine is connected to the inlet of the reheater 18 to achieve steam reheating, the outlet of the reheater 18 is connected to the inlet of the medium-pressure cylinder 6 of the steam turbine, and the outlet of the medium-pressure cylinder 6 of the steam turbine is connected to the inlet of the low-pressure cylinder 7 of the steam turbine. The high-pressure cylinder 5, the medium-pressure cylinder 6 and the low-pressure cylinder 7 of the steam turbine are coaxially arranged with the steam turbine generator 8 through a rigid coupling and connected by a rigid coupling. The exhaust steam of the low-pressure cylinder 7 of the steam turbine is connected to the condenser 9. The condensate at the outlet of the condenser 9 is divided into two routes. One route is connected to the condensate pump 10 through a pipeline. The outlet of the condensate pump 10 is connected to the inlet of the low-pressure economizer 11. The outlet of the low-pressure economizer 11 is connected to the inlet of the low-pressure evaporator 12. The outlet of the low-pressure evaporator 12 is divided into three routes, including one steam side outlet and two water side outlets. The outlet of the steam side is connected to the inlet of the low-pressure superheater 13 through a pipeline. The outlet of the low-pressure superheater 13 is connected to the inlet pipeline of the low-pressure cylinder 7 of the steam turbine. One route is connected to the outlet of the water side of the low-pressure evaporator 12. The outlet of the medium-pressure feed water pump 14 is connected to the inlet of the medium-pressure economizer 15 through a pipeline, the outlet of the medium-pressure feed water pump 14 is connected to the inlet of the medium-pressure economizer 15, the outlet of the medium-pressure economizer 15 is connected to the inlet of the medium-pressure evaporator 16, the outlet of the medium-pressure evaporator 16 is connected to the inlet of the medium-pressure superheater 17, the outlet of the medium-pressure superheater 17 and the exhaust pipe of the high-pressure cylinder 5 of the steam turbine are combined into one pipeline and then connected to the inlet of the reheater 18, the outlet of the water side of the low-pressure evaporator 12 is connected to the inlet of the high-pressure feed water pump 19 through a pipeline, the outlet of the high-pressure feed water pump 19 is connected to the inlet of the high-pressure economizer 20, the outlet of the high-pressure economizer 20 is connected to the inlet of the high-pressure steam drum 21, and the outlet of the high-pressure steam drum 21 is connected to the inlet of the high-pressure superheater 22, forming a whole gas-steam power cycle.

[0030] The outlet of the low-temperature molten salt tank 29 is connected to the inlet of the low-temperature molten salt pump 30 through a pipeline. The outlet of the low-temperature molten salt pump 30 is divided into two routes. One route is connected to the inlet of the gas-salt heat storage control valve 43 through a pipeline. The outlet of the gas-salt heat storage control valve 43 is connected to the inlet of the gas-salt heat exchanger 26. The outlet of the gas-salt heat exchanger 26 is connected to the inlet of the high-temperature molten salt tank 31. The other route of the outlet of the low-temperature molten salt pump 30 is connected to the inlet of the electric heat storage control valve 44 through a pipeline. The outlet of the electric heat storage control valve 44 is connected to the inlet of the molten salt electric heater 28. The outlet of the molten salt electric heater 28 is also connected to the inlet of the high-temperature molten salt tank 31.

[0031] The gas-salt heat exchanger 26 and the molten salt electric heater 28 are arranged in parallel; the outlet of the high-temperature molten salt tank 31 is connected to the inlet of the high-temperature molten salt pump 32 by a pipeline, and the outlet of the high-temperature molten salt pump 32 is connected to the steam-salt heat exchanger 42, the phase change heat exchanger 41 and the water-salt heat exchanger 40 in sequence, and finally connected to the inlet of the low-temperature molten salt tank 29; another path of the condensed water at the outlet of the condenser 9 is connected to the inlet of the heat storage water pump 33 through a pipeline. The outlet of the heat storage feed water pump 33 is divided into two routes, one of which is connected to the inlet of the cold water tank level control valve 34, the outlet of the cold water tank level control valve 34 is connected to the inlet of the cold water tank 35, the outlet of the cold water tank 35 is connected to the inlet of the cold water pump 36, the outlet of the cold water pump 36 is connected to the inlet of the second medium-pressure economizer 27, the outlet of the second medium-pressure economizer 27 is connected to the inlet of the hot water tank 37, the outlet of the hot water tank 37 is connected to the inlet of the hot water pump 38, and the other outlet of the heat storage feed water pump 33 is connected to the inlet of the phase change heat exchanger level control valve 39. After the outlet of the phase change heat exchanger level control valve 39 and the outlet pipeline of the hot water pump 38 are merged, they are sequentially connected to the water-salt heat exchanger 40 and the phase change heat exchanger 41, and finally connected to the inlet of the steam-salt heat exchanger 42, and the outlet of the steam-salt heat exchanger 42 is connected to the heating pipeline of the turbine intermediate pressure cylinder 6.

[0032] The process of the heat storage medium in this embodiment is as follows:

[0033] The exhaust pipe at the outlet of the gas turbine 3 is divided into two paths. During the off-peak period of the power grid, the flue gas bypass damper 23 is fully opened. After the exhaust gas of the gas turbine 3 passes through the flue gas bypass damper 23, it all flows along the flue of the waste heat boiler of the original gas-steam combined cycle cogeneration unit, through the reheater 18, the high-pressure superheater 22, the high-pressure evaporator 21, the high-pressure economizer 20, the medium-pressure superheater 17, the medium-pressure evaporator 16, the medium-pressure economizer 15, the low-pressure superheater 13, the low-pressure evaporator 12 and the low-pressure economizer 11, and finally enters the chimney 24. At this time, the dual-medium energy storage system does not store heat.

[0034] During the off-peak period of power grid, the gas turbine 3 is kept running. By adjusting the opening of the flue gas bypass damper 23, the exhaust gas of part or all of the gas turbine 3 is controlled to flow along the waste heat boiler bypass flue in sequence through the gas-salt heat exchanger 26 and the second medium-pressure economizer 27, and finally enter the chimney 24. At the same time, the condensed water from the outlet of the condenser 9 is pressurized by the heat storage water supply pump 33, and the water level of the cold water tank 35 is controlled by the cold water tank level control valve 34. The outlet water of the cold water tank 35 is pressurized by the cold water pump 36 and enters the second medium-pressure economizer 27 for reverse heat exchange with the gas turbine exhaust. The hot water after heat exchange flows to the hot water tank 37. At the same time, the low-temperature molten salt The low-temperature molten salt at the outlet of the tank 29 is pressurized by the low-temperature molten salt pump 30 and divided into two paths. One path first flows through the gas-salt heat storage control valve 43, then flows through the gas-salt heat exchanger 26 for reverse heat exchange with the gas turbine exhaust, and finally flows to the high-temperature molten salt tank 31; after the steam turbine is reduced to the minimum load or shut down, the other path of low-temperature molten salt first flows through the electric heat storage control valve 44, and then flows through the molten salt electric heater 28, and heats the molten salt heat storage by reducing the total online power of the gas turbine generator 4 and the steam turbine generator 8 to zero. The heated hot molten salt also flows to the high-temperature molten salt tank 31, realizing the heat storage process of the dual-medium energy storage system.

[0035] The process of the heat-releasing working medium in this embodiment is as follows:

[0036] The hot water stored in the hot water tank 37 is pressurized by the hot water pump 38 to become high-pressure hot water. The high-pressure hot water is mixed with the condensed water from the condenser 9, the heat storage feed water pump 33 and the phase change heat exchanger level control valve 39 and releases heat. This process realizes the heat release of the heat storage hot water; the high-temperature molten salt stored in the high-temperature molten salt tank 31 is pressurized by the high-temperature molten salt pump 32 and flows through the steam-salt heat exchanger 42, the phase change heat exchanger 41 and the water-salt heat exchanger 40 in sequence. The low-temperature molten salt after releasing heat flows into the low-temperature molten salt tank 29. This molten salt process realizes the heat release process of the molten salt; the condensed water from the phase change heat exchanger level control valve 39 and the hot water from the hot water pump 38 are mixed and heated, and then flow through the water-salt heat exchanger 40 for preheating. The preheated water flows through the phase change heat exchanger 41 to evaporate into steam, and the steam flows through the steam-salt heat exchanger 42 for superheating, realizing the heat absorption process of the steam, and the generated superheated steam merges with the heat supply extraction steam of the turbine intermediate pressure cylinder 6. The above realizes the heat release process of the dual-medium energy storage system.

[0037] The heat storage and release method of this embodiment is: coupling a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system to achieve "thermal and electric decoupling" of the original cogeneration unit, while ensuring the industrial heat load of the unit and realizing flexible operation of the unit.

[0038] The exhaust duct of the gas turbine 3 is divided into two paths, one path enters the waste heat boiler flue, and the other path enters the waste heat boiler bypass flue. The flue gas bypass baffle 23 is installed at the entrance of the waste heat boiler flue and the waste heat boiler bypass flue, and plays the role of a three-way to control the exhaust gas of the gas turbine 3 to flow to the waste heat boiler flue or the waste heat boiler bypass flue. When the flue gas bypass baffle 23 is fully opened, the exhaust gas of the gas turbine 3 all enters the waste heat boiler flue. When the flue gas bypass baffle 23 is fully closed, the exhaust gas of the gas turbine 3 all enters the waste heat boiler bypass flue. By adjusting the opening of the flue gas bypass baffle 23, the exhaust volume ratio of the exhaust gas of the gas turbine 3 entering the waste heat boiler flue and the waste heat boiler bypass flue can be controlled.

[0039] During the period of average power consumption of the power grid, the exhaust gas of the gas turbine 3 all enters the waste heat boiler, heats the condensate from the condensate pump 10 to generate superheated steam, and then enters the steam turbine for power generation and heat supply. The system operates in the "heat-to-electricity" mode of the original cogeneration unit, and the dual-medium energy storage system is not put into operation. During the period of low power consumption of the power grid, the gas turbine 3 is kept running, and the opening of the flue gas bypass damper 23 is adjusted to control part or all of the exhaust gas of the gas turbine 3 to enter the bypass flue of the waste heat boiler. At the same time, the first-level flue gas heating molten salt heat storage system and the water heat storage system are put into operation, and the low-temperature molten salt from the low-temperature molten salt tank 29 and the cold water from the cold water tank 35 are used to heat the molten salt. Water absorbs the exhaust heat of the gas turbine 3 and stores heat in the gas-salt heat exchanger 26 and the second medium-pressure economizer 27 arranged in the bypass flue of the waste heat boiler, respectively. The high-grade heat is stored in the molten salt heat storage tank, and the low-grade heat is stored in the water storage tank. This can reduce the steam turbine to the minimum load or stop the operation of the steam turbine, and then put the secondary electric heating molten salt heat storage system into operation to store heat. The low-temperature molten salt from the low-temperature molten salt tank 29 flows through the molten salt electric heater 28, and the molten salt heat storage is heated by reducing the total online power of the gas turbine generator 4 and the steam turbine generator 8 to zero. The heat is also stored in the molten salt heat storage tank to realize the heat storage process.

[0040] During the off-peak period of power consumption in the power grid, the dual-medium energy storage system not only stores heat to ensure the heating demand of the unit, but also releases the heat stored in the molten salt and water to heat the feed water to generate steam to supply the thermal load of the unit, and operates in a "storage and release" mode; during the peak period of power consumption in the power grid, the dual-medium energy storage system releases the heat stored in the high-temperature molten salt in the high-temperature molten salt tank 31 and the hot water in the hot water tank 37 to heat the feed water to generate steam, supply the industrial extraction steam of the unit, and at the same time squeeze out the original unit extraction steam, so that the original steam turbine generates peak power.

[0041] The present invention does not elaborate on some of the common technologies of those skilled in the art. The above-described embodiments are only descriptions of preferred implementations of the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementations described. Without departing from the design spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A dual-medium heat storage gas-steam combined cycle cogeneration unit, characterized in that: The invention is composed of an original gas-steam combined cycle heat and power cogeneration unit coupled with a dual-medium energy storage system consisting of a molten salt heat storage system and a water heat storage system; the molten salt heat storage system is divided into two levels according to the nature of the heat storage heat source, the first level is a flue gas heating molten salt heat storage system, and the second level is an electric heating molten salt heat storage system, and the flue gas heating molten salt heat storage system and the electric heating molten salt heat storage system are arranged in parallel; the flue gas heating molten salt heat storage system and the water heat storage system of the first level are arranged in series and then in parallel with the waste heat boiler system of the original gas-steam combined cycle heat and power cogeneration unit; by adjusting the opening of the flue gas bypass damper of the original gas-steam combined cycle heat and power cogeneration unit, the amount of exhaust gas from the gas turbine of the original gas-steam combined cycle heat and power cogeneration unit entering the bypass flue of the waste heat boiler is controlled, and the first level The flue gas heating molten salt heat storage system is responsible for storing the high-grade heat of the exhaust gas of the gas turbine through the gas-salt heat exchanger of the molten salt heat storage system. At the same time, the water heat storage system is responsible for storing the low-grade heat of the exhaust gas of the gas turbine through the second medium-pressure economizer of the water heat storage system. After the steam turbine is reduced to the minimum load or the steam turbine stops running, the secondary electric heating molten salt heat storage system is responsible for storing the heat of the remaining online power of the unit through the molten salt electric heater of the molten salt heat storage system. The high-grade heat is stored in the molten salt heat storage tank, and the low-grade heat is stored in the water storage tank. The stored heat is used to heat the feed water from the heat storage feed water pump, and then the feed water flows through the phase change heat exchanger of the molten salt heat storage system to evaporate into steam, and the steam then flows through the steam-salt heat exchanger of the molten salt heat storage system to generate superheated steam to supply the heat load of the unit.

2. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 1, characterized in that: The original gas-steam combined cycle cogeneration unit includes a compressor, a combustion chamber, a gas turbine, a gas turbine generator, a steam turbine high-pressure cylinder, a steam turbine medium-pressure cylinder, a steam turbine low-pressure cylinder, a steam turbine generator, a condenser, a condensate pump, a low-pressure economizer, a low-pressure evaporator, a low-pressure superheater, a medium-pressure feed water pump, a medium-pressure economizer, a medium-pressure evaporator, a medium-pressure superheater, a reheater, a high-pressure feed water pump, a high-pressure economizer, a high-pressure evaporator, a high-pressure superheater, a flue gas bypass baffle, and a chimney.

3. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 1, characterized in that: The exhaust duct of the gas turbine is divided into two paths, one path enters the waste heat boiler flue, and the other path enters the waste heat boiler bypass flue. The flue gas bypass damper is installed at the entrance of the waste heat boiler flue and the waste heat boiler bypass flue, and plays the role of a three-way to control the exhaust gas of the gas turbine to flow to the waste heat boiler flue or the waste heat boiler bypass flue. When the flue gas bypass damper is fully opened, the exhaust gas of the gas turbine all enters the waste heat boiler flue. When the flue gas bypass damper is fully closed, the exhaust gas of the gas turbine all enters the waste heat boiler bypass flue. By adjusting the opening of the flue gas bypass damper, the exhaust volume ratio of the gas turbine exhaust entering the waste heat boiler flue and the waste heat boiler bypass flue is controlled.

4. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 2, characterized in that: The molten salt heat storage system includes a gas-salt heat exchanger, a molten salt electric heater, a low-temperature molten salt tank, a low-temperature molten salt pump, a high-temperature molten salt tank, a high-temperature molten salt pump, a phase change heat exchanger level control valve, a water-salt heat exchanger, a phase change heat exchanger, a steam-salt heat exchanger, a gas-salt heat storage control valve, and an electric heat storage control valve, wherein the gas-salt heat exchanger and the molten salt electric heater are arranged in parallel; the water heat storage system includes a second medium-pressure economizer, a cold water tank level control valve, a cold water tank, a cold water pump, a hot water tank, and a hot water pump.

5. The dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 1, characterized in that: During the off-peak period of power consumption in the power grid, the dual-medium energy storage system will release the heat stored in the molten salt and water while storing heat, heating the feed water to generate steam to supply the thermal load of the unit, and operate in a "storage and release" mode; during the peak period of power consumption in the power grid, the dual-medium energy storage system will release the heat stored in the high-temperature molten salt tank and the hot water in the hot water tank, heating the feed water to generate steam, supplying the industrial extraction steam of the unit while displacing the original unit extraction steam, and the original steam turbine will generate peak power.

6. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 4, characterized in that: A gas-salt heat exchanger and a second medium-pressure economizer are arranged in sequence inside the bypass flue of the waste heat boiler along the exhaust direction of the gas turbine; the outlet of the low-temperature molten salt tank is connected to the inlet of the low-temperature molten salt pump through a pipeline, and the outlet of the low-temperature molten salt pump is divided into two paths, one of which is connected to the inlet of the gas-salt heat storage control valve through a pipeline, and the outlet of the gas-salt heat storage control valve is connected to the inlet of the gas-salt heat exchanger, and the outlet of the gas-salt heat exchanger is connected to the inlet of the high-temperature molten salt tank, and the other outlet of the low-temperature molten salt pump is connected to the inlet of the electric heat storage control valve through a pipeline, and the outlet of the electric heat storage control valve is connected to the inlet of the molten salt electric heater, and the outlet of the molten salt electric heater is also connected to the inlet of the high-temperature molten salt tank, and the gas-salt heat exchanger and the molten salt electric heater are arranged in parallel; the outlet of the high-temperature molten salt tank is connected to the inlet of the high-temperature molten salt pump by a pipeline, and the outlet of the high-temperature molten salt pump is connected to the steam-salt heat exchanger, the phase change heat exchanger and the water Salt heat exchanger, and finally connected to the inlet of the low-temperature molten salt tank; another way of the condensate at the outlet of the condenser is connected to the inlet of the heat storage feed water pump through a pipeline, the outlet of the heat storage feed water pump is divided into two ways, one way is connected to the inlet of the cold water tank level control valve, the outlet of the cold water tank level control valve is connected to the inlet of the cold water tank, the outlet of the cold water tank is connected to the inlet of the cold water pump, the outlet of the cold water pump is connected to the inlet of the second medium-pressure economizer, the outlet of the second medium-pressure economizer is connected to the inlet of the hot water tank, the outlet of the hot water tank is connected to the inlet of the hot water pump, the other way of the outlet of the heat storage feed water pump is connected to the inlet of the phase change heat exchanger level control valve, after the outlet of the phase change heat exchanger level control valve and the outlet pipeline of the hot water pump are merged, they are connected to the water-salt heat exchanger and the phase change heat exchanger in sequence, and finally connected to the inlet of the steam-salt heat exchanger, and the outlet of the steam-salt heat exchanger is connected to the heating pipeline of the intermediate pressure cylinder of the turbine.

7. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 1, characterized in that: According to the heat storage requirements of the molten salt heat storage system, the gas-salt heat exchanger is single-stage or multi-stage.

8. The dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 1, characterized in that: The unit's heating extraction steam is extracted from the turbine's intermediate pressure cylinder. The extraction position and number of extraction ports in the turbine's high pressure cylinder, turbine's intermediate pressure cylinder, and turbine's low pressure cylinder can be adjusted according to the pressure and temperature of the actual heating load.

9. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 4, characterized in that: During the off-peak period of the power grid, the flue gas bypass damper is fully opened. After passing through the flue gas bypass damper, the exhaust gas of the gas turbine flows along the flue of the waste heat boiler in sequence through the reheater, high-pressure superheater, high-pressure evaporator, high-pressure economizer, medium-pressure superheater, medium-pressure evaporator, medium-pressure economizer, low-pressure superheater, low-pressure evaporator and low-pressure economizer, and finally enters the chimney. At this time, the dual-medium energy storage system is not put into operation; during the off-peak period of the power grid, the gas turbine is kept running, and by adjusting the opening of the flue gas bypass damper, the exhaust gas of part or all of the gas turbine is controlled to flow along the bypass flue of the waste heat boiler in sequence through the gas-salt heat exchanger and the second medium-pressure economizer, and finally enters the chimney. At the same time, the condensate from the outlet of the condenser is boosted by the heat storage feed water pump and passes through the cold water tank level control valve The water level of the cold water tank is controlled. The outlet water of the cold water tank enters the second medium-pressure economizer after being pressurized by the cold water pump and is reversely exchanged with the exhaust gas of the gas turbine. The hot water after heat exchange flows to the hot water tank. At the same time, the low-temperature molten salt at the outlet of the low-temperature molten salt tank is pressurized by the low-temperature molten salt pump and is divided into two paths. One path first flows through the gas-salt heat storage control valve, then flows through the gas-salt heat exchanger and is reversely exchanged with the exhaust gas of the gas turbine, and finally flows to the high-temperature molten salt tank; after the steam turbine is reduced to the minimum load or shut down, the other path of low-temperature molten salt first flows through the electric heat storage control valve, and then flows through the molten salt electric heater. The molten salt heat storage is heated by reducing the total online power of the gas turbine generator and the steam turbine generator to zero. The heated hot molten salt also flows to the high-temperature molten salt tank, realizing the heat storage of the dual-medium energy storage system.

10. A dual-medium heat storage type gas-steam combined cycle cogeneration unit according to claim 4, characterized in that: The hot water stored in the hot water tank is pressurized by the hot water pump and becomes high-pressure hot water. The high-pressure hot water is mixed with the condensed water from the condenser, the heat storage feed water pump and the phase change heat exchanger level control valve and releases heat. This process realizes the heat release of the heat storage hot water; the high-temperature molten salt stored in the high-temperature molten salt tank is pressurized by the high-temperature molten salt pump and flows through the steam-salt heat exchanger, the phase change heat exchanger and the water-salt heat exchanger in sequence. The low-temperature molten salt after releasing heat flows into the low-temperature molten salt tank. This molten salt process realizes the heat release process of the molten salt; the condensed water from the phase change heat exchanger level control valve and the hot water from the hot water pump are mixed and heated, and then flow through the water-salt heat exchanger for preheating. The preheated water flows through the phase change heat exchanger to evaporate into steam, and the steam flows through the steam-salt heat exchanger for superheating, realizing the steam absorption process. The generated superheated steam is combined with the heating extraction steam of the intermediate pressure cylinder of the turbine to realize the heat release of the dual-medium energy storage system.

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