Carnot cell system for heating heat supply network water in cascade mode and operation method of Carnot cell system

Abstract

The invention discloses a Carnot battery system for cascade heating of heat supply network water and an operation method of the Carnot battery system, and belongs to the technical field of Carnot battery systems, the system comprises a steam turbine power generation system, a heat supply network water heating system, an electricity-to-heat system and a storage tank heat storage and release system. Based on a traditional Carnot battery system, the heat supply network heat exchanger is additionally arranged on the heat storage part of the storage tank system, so that the thermoelectric load characteristic interval of the system is expanded, and the operation flexibility of the system is improved. And meanwhile, abandoned electricity of a new energy station can be reduced, and the network access rate of new energy is increased. In addition, the temperature of the heat storage medium entering the heat source heat exchanger is reduced by heating heat supply network water, so that the COP and the round-trip efficiency of the system are improved; the heat exchange loss of heat supply network water is reduced due to the cascade heating system, and the energy utilization rate is increased. Compared with a traditional Carnot cell system, the system has higher efficiency and lower coal consumption, and theoretical reference and technical transformation can be provided for coal-electricity low-carbon flexible transformation.

Description

Technical Field

[0001] The invention relates to the technical field of Carnot battery systems, in particular to a Carnot battery system for stepwise heating of hot water network and an operation method thereof. Background Art

[0002] Renewable energy power generation has become an important development direction of future energy strategy. However, due to the intermittent and volatile nature of new energy, it is difficult to connect it to the grid on a large scale, which in turn brings about an urgent need for the power grid to regulate power. At present, thermal power units in my country still account for the majority of power sources, but due to the limitations of their own structural characteristics, their regulation capabilities are very limited. Therefore, achieving thermal-electric decoupling and improving the low-carbon operation flexibility of cogeneration units are the key to building a new power system with clean energy as the main body.

[0003] Carnot battery, also known as heat pump energy storage technology, consists of three parts: electricity to heat, heat storage and heat to electricity. The molten salt Carnot battery energy storage system for thermal power plant transformation retains the original power generation cycle as the heat to electricity part, adds electric heating or reverse power cycle as the electricity to heat part, and introduces low-cost molten salt heat storage as the large-scale electricity storage part. Because the transformed molten salt Carnot battery energy storage system utilizes the existing coal-fired power plant, the initial investment cost of the project is reduced. This highly potential energy storage system is expected to become a new energy storage system for large-scale electricity storage, promoting the large-scale consumption of renewable energy generation by the power system.

[0004] According to existing relevant literature, although the Carnot battery system can convert waste electricity into heat energy for utilization, it does not substantially increase the rate of new energy power generation access to the grid. At the same time, due to the limitations of the equipment itself, its electricity-to-electricity conversion efficiency is low and is far less cost-effective than direct use. In addition, when the heat-to-electricity system of the Carnot battery is a typical Rankine cycle cogeneration unit, its energy release stage is mostly a boiler replacement solution. Although this solution can reduce coal consumption, it cannot solve the problem of strong thermoelectric coupling. Summary of the invention

[0005] In view of this, the present invention aims at the deficiencies of the prior art and provides a Carnot battery system for stepwise heating of hot water network and an operation method thereof.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a Carnot battery system for step-by-step heating of hot water network, characterized in that it includes a steam turbine power generation system, a hot water network heating system, an electric heat conversion system and a tank heat storage and release system;

[0007] The steam turbine power generation system includes a boiler, wherein the boiler superheater outlet is connected to the inlet of a first mixing valve, the other inlet of the first mixing valve is connected to the cold source outlet of the auxiliary superheater, the outlet of the first mixing valve is connected to the inlet of the high-pressure cylinder, the outlet of the high-pressure cylinder is connected to the inlet of the second diverter valve, the outlet of the second diverter valve is respectively connected to the cold source inlet of the auxiliary reheater and the reheater inlet of the boiler, the inlet of the second mixing valve is respectively connected to the cold source outlet of the auxiliary reheater and the reheater outlet of the boiler, the outlet of the second mixing valve is connected to the inlet of the intermediate pressure cylinder, and the outlet of the intermediate pressure cylinder is respectively connected to the steam inlet of the deaerator The inlet of the fourth diverter valve is connected to the inlet of the low-pressure cylinder and the heat source inlet of the heat network heater, the outlet of the fourth diverter valve is respectively connected to the inlet of the low-pressure cylinder and the heat source inlet of the heat network heater, the outlet of the low-pressure cylinder is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the second feedwater pump, the outlet of the second feedwater pump is connected to the feedwater inlet of the deaerator, the outlet of the deaerator is connected to the inlet of the first feedwater pump, the outlet of the first feedwater pump is connected to the inlet of the third diverter valve, and the outlet of the third diverter valve is respectively connected to the feedwater inlet of the boiler and the cold source inlet of the preheater; the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder and the generator are coaxially connected;

[0008] The heating network water heating system comprises a heater, a cold source inlet of the heater is connected to the return water of the heating network, a cold source outlet of the heater is connected to the cold source inlet of the heating network heater, and the cold source outlet of the heating network heater is connected to the heating network; the heat source outlet of the heating network heater is connected to the hot well of the condenser;

[0009] The electric heat conversion system includes a compressor, the inlet of the compressor is connected to the cold source outlet of the heat recovery heat exchanger, the outlet of the compressor is connected to the heat source inlet of the heat source heat exchanger, the heat source outlet of the heat source heat exchanger is connected to the heat source inlet of the heat recovery heat exchanger, the heat source outlet of the heat recovery heat exchanger is connected to the inlet of the auxiliary steam turbine, the outlet of the auxiliary steam turbine is connected to the cold source inlet of the cold source heat exchanger, and the cold source outlet of the cold source heat exchanger is connected to the cold source inlet of the heat recovery heat exchanger;

[0010] The storage tank heat storage and release system includes a high-temperature storage tank, the outlet of the high-temperature storage tank is connected to the inlet of the second molten salt circulation pump, the outlet of the second molten salt circulation pump is connected to the inlet of the first diverter valve, the outlet of the first diverter valve is respectively connected to the heat source inlets of the auxiliary superheater and the auxiliary reheater, the inlet of the mixing valve is respectively connected to the heat source outlets of the auxiliary superheater and the auxiliary reheater, the outlet of the mixing valve is connected to the heat source inlet of the evaporator, the heat source outlet of the evaporator is connected to the heat source inlet of the preheater, the heat source outlet of the preheater is connected to the inlet of the first throttle valve, the outlet of the first throttle valve is connected to the inlet of the low-temperature storage tank, the cold source outlet of the preheater is connected to the cold source inlet of the evaporator, and the cold source outlet of the evaporator is connected to the cold source inlet of the auxiliary superheater; the outlet of the low-temperature storage tank is connected to the inlet of the first molten salt circulation pump, the outlet of the first molten salt circulation pump is connected to the heat source inlet of the heater, the heat source outlet of the heater is connected to the cold source inlet of the heat source heat exchanger, the cold source outlet of the heat source heat exchanger is connected to the inlet of the second throttle valve, and the outlet of the second throttle valve is connected to the inlet of the high-temperature storage tank.

[0011] Furthermore, in the electric-to-heat system, the power for the compressor is provided by the auxiliary steam turbine, the excess power of the thermal power plant and the abandoned power of the new energy station.

[0012] Furthermore, in the hot network water heating system, the mass flow rate of the heated hot network water is determined by the mass flow rate of the working fluid flowing from the low-temperature storage tank to the high-temperature storage tank and the exhaust steam of the medium-pressure cylinder diverted by the fourth diverter valve.

[0013] Furthermore, in the electric heat conversion system and the storage tank heat storage and release system, the heat storage medium in the low-temperature storage tank first heats the hot network water to 80°C, and then the heat storage medium enters the heat source heat exchanger for heating, and the hot network water then enters the hot network heater to be heated to the specified temperature of the hot network water supply.

[0014] Furthermore, the operation method of the Carnot battery system for step-by-step heating of hot network water includes: when abandoned power enters the electric heat conversion system and the storage tank heat storage and release system is in a heat storage state, the hot network water first enters the heater for heating, and then is heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder; when no abandoned power enters the electric heat conversion system and the storage tank heat storage and release system is in a heat release state, the hot network water does not enter the heater, but is directly heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder; when abandoned power enters the electric heat conversion system and the storage tank heat storage and release system is in a combined storage and release operation state, the hot network water first enters the heater for heating, and then is heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] Based on the traditional molten salt Carnot battery system for thermal power plants, the present invention adds a heat network heat exchanger to the heat storage part of the tank system to expand the system's thermal load characteristic range and increase the system's operational flexibility. At the same time, it can also reduce the power abandonment of new energy sites and increase the grid-connected rate of new energy. In addition, by heating the heat network water to reduce the temperature of the heat storage medium entering the heat source heat exchanger, the system's COP and round-trip efficiency can be improved; the heat network water also reduces heat exchange losses due to the cascade heating system, thereby improving energy utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of the Carnot battery system for stepwise heating of hot water network of the present invention;

[0018] Figure 2 It is a schematic diagram of the system structure when abandoned electricity enters the electric-to-heat system and the storage tank heat storage and release system is in a heat storage state;

[0019] Figure 3 It is a schematic diagram of the system structure when there is no abandoned electricity entering the electric-to-heat system and the storage tank heat storage and release system is in a heat release state;

[0020] Figure 4 It is a schematic diagram of the system structure when abandoned electricity enters the electric-to-heat system and the storage tank heat storage and release system is in a combined heat storage and release operation state;

[0021] In the figure: 1-compressor, 2-heat source heat exchanger, 3-regenerative heat exchanger, 4-cold source heat exchanger, 5-heater, 6-auxiliary steam turbine, 7-first molten salt circulation pump, 8-low temperature storage tank, 9-generator, 10-first throttle valve, 11-preheater, 12-evaporator, 13-mixing valve, 14-auxiliary superheater, 15-second throttle valve, 16-high temperature storage tank, 17-second molten salt circulation pump, 18-first diverter valve, 19-auxiliary reheater, 20-first mixing valve, 21-second diverter valve, 22-boiler, 23-third diverter valve, 24-first feed water pump, 25-deaerator, 26-high pressure cylinder, 27-second mixing valve, 28-fourth diverter valve, 29-medium pressure cylinder, 30-low pressure cylinder, 31-heat network heater, 32-condenser, 33-second feed water pump. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0023] Example: Refer to Figure 1 A Carnot battery system for cascade heating of hot water grid includes a steam turbine power generation system, a hot water grid heating system, an electric heat conversion system and a tank heat storage and release system.

[0024] The steam turbine power generation system includes a boiler 22, the outlet of the superheater of the boiler 22 is connected to the inlet of the first mixing valve 20, the other inlet of the first mixing valve 20 is connected to the cold source outlet of the auxiliary superheater 14, the outlet of the first mixing valve 20 is connected to the inlet of the high-pressure cylinder 26, the outlet of the high-pressure cylinder 26 is connected to the inlet of the second diverter valve 21, the outlet of the second diverter valve 21 is respectively connected to the cold source inlet of the auxiliary reheater 19 and the reheater inlet of the boiler 22, the inlet of the second mixing valve 27 is respectively connected to the cold source outlet of the auxiliary reheater 19 and the reheater outlet of the boiler 22, the outlet of the second mixing valve 27 is connected to the inlet of the intermediate pressure cylinder 29, and the outlet of the intermediate pressure cylinder 29 is respectively connected to the steam inlet of the deaerator 25. The outlet of the fourth diverter valve 28 is connected to the inlet of the low-pressure cylinder 30 and the heat source inlet of the heat network heater 31, respectively. The outlet of the low-pressure cylinder 30 is connected to the inlet of the condenser 32, the outlet of the condenser 32 is connected to the inlet of the second feedwater pump 33, the outlet of the second feedwater pump 33 is connected to the feedwater inlet of the deaerator 25, the outlet of the deaerator 25 is connected to the inlet of the first feedwater pump 24, the outlet of the first feedwater pump 24 is connected to the inlet of the third diverter valve 23, and the outlet of the third diverter valve 23 is connected to the feedwater inlet of the boiler 22 and the cold source inlet of the preheater 11, respectively; the high-pressure cylinder 26, the medium-pressure cylinder 29, the low-pressure cylinder 30 and the generator 9 are coaxially connected;

[0025] The hot network water heating system includes a heater 5, a cold source inlet of the heater 5 is connected to the hot network return water, a cold source outlet of the heater 5 is connected to the cold source inlet of the hot network heater 31, and a cold source outlet of the hot network heater 31 is connected to the hot network; a heat source outlet of the hot network heater 31 is connected to the hot well of the condenser 32;

[0026] The electric heat conversion system comprises a compressor 1, the inlet of the compressor 1 is connected to the cold source outlet of the heat recovery heat exchanger 3, the outlet of the compressor 1 is connected to the heat source inlet of the heat source heat exchanger 2, the heat source outlet of the heat source heat exchanger 2 is connected to the heat source inlet of the heat recovery heat exchanger 3, the heat source outlet of the heat recovery heat exchanger 3 is connected to the inlet of the auxiliary steam turbine 6, the outlet of the auxiliary steam turbine 6 is connected to the cold source inlet of the cold source heat exchanger 4, and the cold source outlet of the cold source heat exchanger 4 is connected to the cold source inlet of the heat recovery heat exchanger 3;

[0027] The storage tank heat storage and release system includes a high-temperature storage tank 16, the outlet of the high-temperature storage tank 16 is connected to the inlet of the second molten salt circulation pump 17, the outlet of the second molten salt circulation pump 17 is connected to the inlet of the first diverter valve 18, the outlet of the first diverter valve 18 is respectively connected to the heat source inlets of the auxiliary superheater 14 and the auxiliary reheater 19, the inlet of the mixing valve 13 is respectively connected to the heat source outlets of the auxiliary superheater 14 and the auxiliary reheater 19, the outlet of the mixing valve 13 is connected to the heat source inlet of the evaporator 12, the heat source outlet of the evaporator 12 is connected to the heat source inlet of the preheater 11, and the heat source outlet of the preheater 11 is connected to the first throttle valve 1 0, the outlet of the first throttle valve 10 is connected to the inlet of the low-temperature storage tank 8, the cold source outlet of the preheater 11 is connected to the cold source inlet of the evaporator 12, and the cold source outlet of the evaporator 12 is connected to the cold source inlet of the auxiliary superheater 14; the outlet of the low-temperature storage tank 8 is connected to the inlet of the first molten salt circulation pump 7, the outlet of the first molten salt circulation pump 7 is connected to the heat source inlet of the heater 5, the heat source outlet of the heater 5 is connected to the cold source inlet of the heat source heat exchanger 2, the cold source outlet of the heat source heat exchanger 2 is connected to the inlet of the second throttle valve 15, and the outlet of the second throttle valve 15 is connected to the inlet of the high-temperature storage tank 16.

[0028] In the electric-to-heat system, the power of the compressor 1 is provided by the auxiliary steam turbine 6, the excess power of the thermal power plant and the abandoned power of the new energy station.

[0029] In the hot network water heating system, the mass flow rate of the heated hot network water is determined by the mass flow rate of the working fluid flowing from the low-temperature storage tank 8 to the high-temperature storage tank 16 and the exhaust volume of the medium-pressure cylinder 29 diverted by the fourth diverter valve 28.

[0030] In the electric heat conversion system and the storage tank heat storage and release system, the heat storage medium in the low-temperature storage tank 8 first heats the hot network water to 80°C, and then the heat storage medium enters the heat source heat exchanger 2 for heating, and the hot network water then enters the hot network heater 31 to be heated to the specified temperature of the hot network water supply.

[0031] Operation method of Carnot battery system for cascade heating of hot water network: Figure 2 When abandoned electricity enters the electric-to-heat system and the storage tank heat storage and release system is in the heat storage state, the hot network water first enters the heater 5 for heating, and then is heated to the specified temperature through the exhaust steam of the medium pressure cylinder 29; Figure 3 When no abandoned electricity enters the electric-to-heat system and the storage tank heat storage system is in the heat release state, the hot network water does not enter the heater 5, but is directly heated to the specified temperature through the exhaust steam of the intermediate pressure cylinder 29; Figure 4 When abandoned electricity enters the electric-to-heat system and the storage tank heat storage and release system is in a combined heat storage and release operation state, the hot network water first enters the heater 5 for heating, and then is heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder 29.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art can still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A Carnot battery system for stepwise heating of hot water network, characterized in that: It includes steam turbine power generation system, heat network water heating system, electric heat conversion system and tank heat storage and release system; The steam turbine power generation system comprises a boiler (22), wherein the outlet of the superheater of the boiler (22) is connected to the inlet of a first mixing valve (20), the other inlet of the first mixing valve (20) is connected to the cold source outlet of the auxiliary superheater (14), the outlet of the first mixing valve (20) is connected to the inlet of a high-pressure cylinder (26), the outlet of the high-pressure cylinder (26) is connected to the inlet of a second diverter valve (21), the outlet of the second diverter valve (21) is respectively connected to the cold source inlet of the auxiliary reheater (19) and the reheater inlet of the boiler (22), the inlet of the second mixing valve (27) is respectively connected to the cold source outlet of the auxiliary reheater (19) and the reheater outlet of the boiler (22), the outlet of the second mixing valve (27) is connected to the inlet of an intermediate pressure cylinder (29), the outlet of the intermediate pressure cylinder (29) is respectively connected to the steam inlet of a deaerator (25), and the inlet of the fourth diverter valve (28), the outlet of the fourth diverter valve (28) is respectively connected to the inlet of the low-pressure cylinder (30) and the heat source inlet of the heat network heater (31), the outlet of the low-pressure cylinder (30) is connected to the inlet of the condenser (32), the outlet of the condenser (32) is connected to the inlet of the second feedwater pump (33), the outlet of the second feedwater pump (33) is connected to the feedwater inlet of the deaerator (25), the outlet of the deaerator (25) is connected to the inlet of the first feedwater pump (24), the outlet of the first feedwater pump (24) is connected to the inlet of the third diverter valve (23), and the outlet of the third diverter valve (23) is respectively connected to the feedwater inlet of the boiler (22) and the cold source inlet of the preheater (11); the high-pressure cylinder (26), the medium-pressure cylinder (29), the low-pressure cylinder (30) and the generator (9) are coaxially connected; The heating network water heating system comprises a heater (5), a cold source inlet of the heater (5) is connected to the return water of the heating network, a cold source outlet of the heater (5) is connected to the cold source inlet of the heating network heater (31), and a cold source outlet of the heating network heater (31) is connected to the heating network; and a heat source outlet of the heating network heater (31) is connected to a hot well of a condenser (32); The electric heat conversion system comprises a compressor (1), wherein the inlet of the compressor (1) is connected to the cold source outlet of the heat recovery heat exchanger (3), the outlet of the compressor (1) is connected to the heat source inlet of the heat source heat exchanger (2), the heat source outlet of the heat source heat exchanger (2) is connected to the heat source inlet of the heat recovery heat exchanger (3), the heat source outlet of the heat recovery heat exchanger (3) is connected to the inlet of the auxiliary steam turbine (6), the outlet of the auxiliary steam turbine (6) is connected to the cold source inlet of the cold source heat exchanger (4), and the cold source outlet of the cold source heat exchanger (4) is connected to the cold source inlet of the heat recovery heat exchanger (3); The storage tank heat storage and release system comprises a high-temperature storage tank (16), the outlet of the high-temperature storage tank (16) is connected to the inlet of a second molten salt circulation pump (17), the outlet of the second molten salt circulation pump (17) is connected to the inlet of a first diverter valve (18), the outlet of the first diverter valve (18) is respectively connected to the heat source inlets of an auxiliary superheater (14) and an auxiliary reheater (19), the inlet of a mixing valve (13) is respectively connected to the heat source outlets of the auxiliary superheater (14) and the auxiliary reheater (19), the outlet of the mixing valve (13) is connected to the heat source inlet of an evaporator (12), the heat source outlet of the evaporator (12) is connected to the heat source inlet of a preheater (11), and the heat source outlet of the preheater (11) is connected to the first throttle valve ( The inlet of the low-temperature storage tank (8) is connected to the inlet of the first molten salt circulation pump (7), the outlet of the first molten salt circulation pump (7) is connected to the heat source inlet of the heater (5), the heat source outlet of the heater (5) is connected to the heat source inlet of the heat source heat exchanger (2), the heat source outlet of the heat source heat exchanger (2) is connected to the inlet of the second throttle valve (15), and the outlet of the second throttle valve (15) is connected to the inlet of the high-temperature storage tank (16).

2. The Carnot battery system for stepwise heating of hot water network according to claim 1 is characterized in that: The power of the compressor (1) is provided by the auxiliary steam turbine (6), the excess power of the thermal power plant and the abandoned power of the new energy station.

3. The Carnot battery system for stepwise heating of hot water network according to claim 1 is characterized in that: The mass flow rate of the heated hot network water is determined by the mass flow rate of the working fluid flowing from the low-temperature storage tank (8) to the high-temperature storage tank (16) and the exhaust volume of the medium-pressure cylinder (29) diverted by the fourth diverter valve (28).

4. The Carnot battery system for stepwise heating of hot water network according to claim 1 is characterized in that: The heat storage medium in the low temperature storage tank (8) first heats the hot network water to 80°C, and then the heat storage medium enters the heat source heat exchanger (2) for heating, and the hot network water then enters the hot network heater (31) for heating to the specified temperature of the hot network water supply.

5. The method for operating the Carnot battery system for stepwise heating of hot water network according to any one of claims 1 to 4, characterized in that: include: When abandoned electricity enters the electric heat conversion system and the storage tank heat storage and release system is in a heat storage state, the hot network water first enters the heater (5) for heating, and then is heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder (29); when no abandoned electricity enters the electric heat conversion system and the storage tank heat storage and release system is in a heat release state, the hot network water does not enter the heater (5) and is directly heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder (29); when abandoned electricity enters the electric heat conversion system and the storage tank heat storage and release system is in a combined operation state of heat storage and heat release, the hot network water first enters the heater (5) for heating, and then is heated to a specified temperature through the exhaust steam of the intermediate pressure cylinder (29).

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