Combined heat and power generation system coupled with electric heater and molten salt heat storage system and scheduling strategy

Abstract

The invention discloses a combined heat and power generation system coupled with an electric heater and a molten salt heat storage system and a scheduling strategy. The combined heat and power generation system comprises a combined heat and power generation unit, an electric heating system and the molten salt heat storage system. When the combined heat and power generation unit receives a power grid frequency modulation instruction, a part of generated energy generated by the generator is sent to the electric heater to heat cold fused salt which comes from the cold salt tank and passes through the cold salt valve, the heated fused salt is stored in the hot salt tank, and in the whole process, the generated energy input into the power grid by the combined heat and power generation unit is rapidly reduced; when the combined heat and power generation unit receives a power grid peak regulation instruction and network access electric quantity needs to be rapidly increased, hot molten salt stored in a hot salt tank releases heat in a molten salt radiator, saturated water which is extracted from a deaerator and pressurized by a heat supply water feed pump is heated into steam in the molten salt radiator, and the steam is heated into steam through a steam generator. In the whole process, more exhaust steam of the medium-pressure cylinder is fed into the low-pressure cylinder for power generation, and the power generation amount, input into the power grid, of the cogeneration unit is rapidly increased.

Description

Technical Field

[0001] The present invention relates to the technical field of improving the flexibility of operation of a cogeneration unit, and in particular to a cogeneration system and a scheduling strategy for coupling an electric heater and a molten salt heat storage system. Background Art

[0002] Building a clean, low-carbon, safe and efficient new energy system is an important way to cope with the increasingly severe global warming problem and achieve global net zero carbon emissions. Distributed green electricity, represented mainly by wind power and photovoltaic power, has the advantages of sustainable development and relatively net zero carbon emissions, but green electricity supply is intermittent, unstable and unpredictable. With the continuous increase in the proportion of distributed green electricity in the energy system, power quality problems such as grid voltage sag, fluctuation and flicker, and voltage over-limit occur frequently, bringing more uncertainty and randomness to the power system. Therefore, the grid side has put forward relevant requirements for thermal power units to participate in peak load regulation and frequency regulation. However, due to the characteristics of "electrical and thermal coupling", the operating range of the electric load of the cogeneration unit is affected by the thermal load, and its own ability to participate in the peak load regulation and frequency regulation of the grid is limited. In order to promote the safe and stable access of new energy power generation to the grid, it is urgent to improve the flexibility of the operation of the cogeneration unit.

[0003] The cogeneration unit is responsible for supplying power to the grid and heat to heat users at the same time. On the premise of ensuring the stable heat supply to heat users, the flexibility of the cogeneration unit in supplying power to the grid can be effectively improved to meet the needs of peak load and frequency regulation of the grid, which is an important guarantee for promoting the access of renewable power to the grid and maintaining the safety and stability of the power system. Summary of the invention

[0004] To solve the above problems, the purpose of the present invention is to propose a cogeneration system and scheduling strategy that couples an electric heater and a molten salt heat storage system. The system couples an electric heating system and a molten salt heat storage system on the basis of a cogeneration unit, utilizes an electric heater to improve the downward regulation capability of the cogeneration unit, and utilizes a molten salt heat storage system to improve the upward regulation capability of the cogeneration unit, thereby effectively achieving the purpose of improving the flexible operation capability of the cogeneration unit.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is:

[0006] A heat and power cogeneration system coupled with an electric heater and a molten salt heat storage system, characterized in that it comprises a heat and power cogeneration unit, an electric heating system and a molten salt heat storage system;

[0007] In the electric heating system, the inlet of the transformer 11 is connected to the outlet of the generator 6 of the cogeneration unit, the outlet of the transformer 11 is connected to the inlet of the relay 12, and the outlet of the relay 12 is connected to the electrical port of the electric heater 13;

[0008] In the molten salt heat storage system, the outlet of the cold salt tank 14 is connected to the inlet of the cold salt valve 15, the outlet of the cold salt valve 15 is connected to the cold side inlet of the molten salt of the electric heater 13, the cold side outlet of the molten salt of the electric heater 13 is connected to the inlet of the hot salt tank 16, the outlet of the hot salt tank 16 is connected to the inlet of the hot salt valve 17, the outlet of the hot salt valve 17 is connected to the hot side inlet of the molten salt radiator 18, and the hot side outlet of the molten salt radiator 18 is connected to the inlet of the cold salt tank 14; the inlet of the heating water supply valve 19 is connected to the outlet of the deaerator 8, the outlet of the heating water supply valve 19 is connected to the inlet of the heating water supply pump 20, and the outlet of the heating water supply pump 20 is connected to the cold side inlet of the molten salt radiator 18, and the steam is transported from the cold side outlet of the molten salt radiator 18 to the heat user through the turbine steam supply valve 10;

[0009] After the combined heat and power unit generates electricity by the generator 6, part of it is supplied to the power grid, and part of it is used to heat the molten salt through the electric heater 13; when the combined heat and power unit receives frequency regulation and peak regulation instructions, the needs of frequency regulation and peak regulation are met by adjusting the heat storage and release of the electric heater and the molten salt heat storage system.

[0010] During the heat storage process of the molten salt heat storage system, the power generated from the generator 6 through the transformer 11 and the relay 12 is sent to the electric heater 13 as a source of electric energy for heating the molten salt; the cold molten salt is in the cold salt tank 14, and is heated in the electric heater 13 through the cold salt valve 15 to become hot molten salt and stored in the hot salt tank 16.

[0011] During the heat release process of the molten salt heat storage system, the hot molten salt in the hot salt tank 16 releases heat in the molten salt heat releaser 18 through the hot salt valve 17; saturated water is obtained from the deaerator 8 of the cogeneration unit through the heating water supply valve 19, and the saturated water is pressurized by the heating water supply pump 20. It is heated into steam in the molten salt heat releaser 18 and then transported to the heat user through the turbine heating valve 10.

[0012] The scheduling strategy of a cogeneration system coupling an electric heater and a molten salt heat storage system is as follows: when the cogeneration unit receives a frequency modulation instruction from the power grid and needs to quickly reduce the amount of electricity entering the grid, a portion of the power generated by the generator 6 is sent to the electric heater 13 through the transformer 11 and the relay 12 to heat the cold molten salt from the cold salt tank 14 through the cold salt valve 15, and the heated molten salt is stored in the hot salt tank 16. The whole process causes the power generation input to the power grid by the cogeneration unit to drop rapidly;

[0013] When the cogeneration unit receives a peak load regulation instruction from the power grid and needs to quickly increase the amount of electricity entering the grid, the hot molten salt stored in the hot salt tank 16 releases heat in the molten salt heat releaser 18 through the hot salt valve 17, and the saturated water extracted from the deaerator 8 through the heating water supply valve 19 and pressurized by the heating water supply pump 20 is heated into steam in the molten salt heat releaser 18 to replace part of the exhaust steam of the intermediate pressure cylinder 3 and transported to the heat user through the turbine heating valve 10. The whole process enables more exhaust steam of the intermediate pressure cylinder 3 to be sent to the low pressure cylinder 4 to generate electricity, and the power generation of the cogeneration unit input to the power grid increases rapidly.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) The present invention provides a cogeneration system and a scheduling strategy for coupling an electric heater and a molten salt heat storage system, which adjusts the amount of power generated by the cogeneration unit entering the power grid through the electric heating system and the molten salt heat storage system, thereby increasing the load change rate of the cogeneration unit and improving the ability of the cogeneration unit to participate in frequency regulation;

[0016] (2) The present invention realizes thermal-electric decoupling through an electric heating system and a molten salt energy storage system, expands the electric-thermal load operation range of the cogeneration unit, improves the ability of the cogeneration unit to participate in peak load regulation, and increases the flexibility of the operation of the cogeneration unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A diagram of a cogeneration system of the present invention coupling an electric heater and a molten salt heat storage system.

[0018] In the figure: 1 is a boiler, 2 is a high-pressure cylinder, 3 is a medium-pressure cylinder, 4 is a low-pressure cylinder, 5 is a condenser, 6 is a generator, 7 is a condensate pump, 8 is a deaerator, 9 is a feed water pump, 10 is a turbine heating valve, 11 is a transformer, 12 is a relay, 13 is an electric heater, 14 is a cold salt tank, 15 is a cold salt valve, 16 is a hot salt tank, 17 is a hot salt valve, 18 is a molten salt exotherm, 19 is a heating feed water valve, and 20 is a heating feed water pump. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figure 1As shown, a heat and power cogeneration system coupled with an electric heater and a molten salt heat storage system of the present invention comprises a heat and power cogeneration unit, an electric heating system and a molten salt heat storage system; the heat and power cogeneration unit comprises a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a condenser 5, a generator 6, a condensate pump 7, a deaerator 8, a feed water pump 9, and a turbine heating valve 10; the boiler 1 generates main steam, enters the high-pressure cylinder 2 to do work, and then returns to the boiler 1 to be heated again to become reheated steam, and the reheated steam enters the medium-pressure cylinder 3 to do work and then enters the low-pressure cylinder 4, and finally the exhaust steam of the low-pressure cylinder 4 is condensed by the condenser 5, passes through the condensate pump 7, passes through the heat recovery system including the deaerator 8 and is pressurized by the feed water pump 9 and then returns to the boiler 1 for circulation; at the same time, the exhaust steam of the medium-pressure cylinder 3 supplies heat to heat users through the turbine steam supply valve 10.

[0021] In the electric heating system, the inlet of the transformer 11 is connected to the outlet of the generator 6 , the outlet of the transformer 11 is connected to the inlet of the relay 12 , and the outlet of the relay 12 is connected to the electrical port of the electric heater 13 .

[0022] In the molten salt energy storage system, the outlet of the cold salt tank 14 is connected to the inlet of the cold salt valve 15, the outlet of the cold salt valve 15 is connected to the cold side inlet of the molten salt of the electric heater 13, the cold side outlet of the molten salt of the electric heater 13 is connected to the inlet of the hot salt tank 16, the outlet of the hot salt tank 16 is connected to the inlet of the hot salt valve 17, the outlet of the hot salt valve 17 is connected to the hot side inlet of the molten salt radiator 18, and the hot side outlet of the molten salt radiator 18 is connected to the inlet of the cold salt tank 14; the inlet of the heating water supply valve 19 is connected to the outlet of the deaerator 8, the outlet of the heating water supply valve 19 is connected to the inlet of the heating water supply pump 20, and the outlet of the heating water supply pump 20 is connected to the cold side inlet of the molten salt radiator 18, and the steam is transported from the cold side outlet of the molten salt radiator 18 to the heat user through the turbine steam supply valve 10.

[0023] After the combined heat and power unit generates electricity from the generator 6, part of it is supplied to the grid, and part of it is heated by the electric heater 13 to heat the molten salt. When the combined heat and power unit receives frequency regulation and peak regulation instructions, the needs of frequency regulation and peak regulation are met by adjusting the heat storage and release of the electric heater and the molten salt heat storage system.

[0024] During the heat storage process of the molten salt heat storage system, the power generated from the generator 6 through the transformer 11 and the relay 12 is sent to the electric heater 13 as a source of electric energy for heating the molten salt. The cold molten salt is in the cold salt tank 14, and is heated in the electric heater 13 through the cold salt valve 15 to become hot molten salt and stored in the hot salt tank 16.

[0025] During the heat release process of the molten salt heat storage system, the hot molten salt in the hot salt tank 16 releases heat in the molten salt heat releaser 18 through the hot salt valve 17. Saturated water is obtained from the deaerator 8 through the heating water supply valve 19, and the saturated water is pressurized by the heating water supply pump 20, and then heated into steam in the molten salt heat releaser 18, and then transported to the heat user through the turbine heating valve 10.

[0026] According to the scheduling strategy of the cogeneration system coupled with the electric heater and the molten salt heat storage system described in the present invention, when the cogeneration unit receives the frequency modulation instruction of the power grid and needs to quickly reduce the amount of power entering the grid, a part of the power generated by the generator 6 is sent to the electric heater 13 through the transformer 11 and the relay 12 to heat the cold molten salt from the cold salt tank 14 through the cold salt valve 15, and the heated molten salt is stored in the hot salt tank 16. The whole process causes the power generation input to the power grid by the cogeneration unit to drop rapidly.

[0027] When the cogeneration unit receives a peak load regulation instruction from the power grid and needs to quickly increase the amount of electricity entering the grid, the hot molten salt stored in the hot salt tank 16 releases heat in the molten salt heat releaser 18 through the hot salt valve 17, and the saturated water extracted from the deaerator 8 through the heating water supply valve 19 and pressurized by the heating water supply pump 20 is heated into steam in the molten salt heat releaser 18 to replace part of the exhaust steam of the intermediate pressure cylinder 3 and transported to the heat user through the turbine heating valve 10. The whole process enables more exhaust steam of the intermediate pressure cylinder 3 to be sent to the low pressure cylinder 4 to generate electricity, and the power generation of the cogeneration unit input to the power grid increases rapidly.

Claims

1. A cogeneration system of coupling an electric heater and a molten salt heat storage system, characterized in that: It includes a combined heat and power unit, an electric heating system and a molten salt heat storage system; In the electric heating system, the inlet of the transformer (11) is connected to the outlet of the generator (6) of the cogeneration unit, the outlet of the transformer (11) is connected to the inlet of the relay (12), and the outlet of the relay (12) is connected to the power port of the electric heater (13); In the molten salt heat storage system, the outlet of the cold salt tank (14) is connected to the inlet of the cold salt valve (15), the outlet of the cold salt valve (15) is connected to the cold side inlet of the molten salt of the electric heater (13), the cold side outlet of the molten salt of the electric heater (13) is connected to the inlet of the hot salt tank (16), the outlet of the hot salt tank (16) is connected to the inlet of the hot salt valve (17), the outlet of the hot salt valve (17) is connected to the hot side inlet of the molten salt radiator (18), and the hot side outlet of the molten salt radiator (18) is connected to the inlet of the cold salt tank (14); the inlet of the heating water supply valve (19) is connected to the outlet of the deaerator (8), the outlet of the heating water supply valve (19) is connected to the inlet of the heating water supply pump (20), and the outlet of the heating water supply pump (20) is connected to the cold side inlet of the molten salt radiator (18), and the steam is transported from the cold side outlet of the molten salt radiator (18) to the heat user through the steam turbine steam supply valve (10); After the combined heat and power unit generates electricity from the generator (6), part of it is supplied to the power grid, and part of it is used to heat the molten salt through the electric heater (13); when the combined heat and power unit receives frequency regulation and peak regulation instructions, the needs of frequency regulation and peak regulation are met by adjusting the heat storage and release of the electric heater and the molten salt heat storage system.

2. A cogeneration system of coupling an electric heater and a molten salt heat storage system as claimed in claim 1, characterized in that: During the heat storage process of the molten salt heat storage system, the power generated by the generator (6) through the transformer (11) and the relay (12) is sent to the electric heater (13) as a source of electric energy for heating the molten salt; the cold molten salt in the cold salt tank (14) is heated in the electric heater (13) through the cold salt valve (15) to become hot molten salt and stored in the hot salt tank (16).

3. A cogeneration system of coupling an electric heater and a molten salt heat storage system as claimed in claim 1, characterized in that: During the heat release process of the molten salt heat storage system, the hot molten salt in the hot salt tank (16) releases heat in the molten salt heat releaser (18) through the hot salt valve (17); saturated water is obtained from the deaerator (8) of the cogeneration unit through the heating water supply valve (19), and the saturated water is pressurized by the heating water supply pump (20), and then heated into steam in the molten salt heat releaser (18), and then transported to the heat user through the turbine heating valve (10).

4. A scheduling strategy for a cogeneration system of a coupled electric heater and a molten salt heat storage system according to any one of claims 1 to 3, characterized in that: When the cogeneration unit receives a frequency modulation instruction from the power grid and needs to quickly reduce the amount of electricity fed into the grid, a portion of the electricity generated by the generator (6) is sent to the electric heater (13) through the transformer (11) and the relay (12) to heat the cold molten salt from the cold salt tank (14) through the cold salt valve (15), and the heated molten salt is stored in the hot salt tank (16). The whole process causes the amount of electricity fed into the power grid by the cogeneration unit to drop rapidly; When the cogeneration unit receives a peak load regulation instruction from the power grid and needs to quickly increase the amount of electricity entering the grid, the hot molten salt stored in the hot salt tank (16) is released through the hot salt valve (17) in the molten salt heat releaser (18), and the saturated water extracted from the deaerator (8) through the heating water supply valve (19) and pressurized by the heating water supply pump (20) is heated into steam in the molten salt heat releaser (18) to replace part of the exhaust steam of the intermediate pressure cylinder (3) and to be transported to the heat user through the turbine heating valve (10). The whole process allows more exhaust steam of the intermediate pressure cylinder (3) to be sent to the low pressure cylinder (4) to generate electricity, and the power generation input to the power grid by the cogeneration unit increases rapidly.

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