Double-unit heat regeneration unit peak shaving system coupled with fused salt electric heater and operation method of double-unit heat regeneration unit peak shaving system coupled with fused salt electric heater

Abstract

The invention discloses a double-unit heat regeneration unit peak regulation system coupled with a fused salt electric heater and an operation method. The double-unit heat regeneration unit peak regulation system coupled with the fused salt electric heater comprises a coal-fired power generator unit thermodynamic system and a fused salt heat storage system which is coupled with the coal-fired power generator unit thermodynamic system and comprises the fused salt electric heater, a fused salt heat storage tank, a fused salt pump, a fused salt heat exchanger and the like. The fused salt heat storage system is provided with two fused salt pumps and two fused salt adjusting valves to control the flow of fused salt entering a fused salt electric heater and a fused salt heat exchanger, and it can be guaranteed that the coal-fired power generation unit stably operates in the rapid load changing period. By adjusting the power of the fused salt electric heater and the working medium flow of the fused salt heat exchanger, the peak regulation performance of the coal-fired power generation unit can be improved so as to meet the rapid peak regulation requirement of the coal-fired power generation unit; the peak regulation flexibility of the double-unit regenerative coal-fired power generation unit can be improved, and the operation stability of the unit can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a peak-shaving system of a dual-machine heat recovery unit coupled with a molten salt electric heater and an operation method thereof. Background Art

[0002] New energy sources, especially solar and wind energy, have brought new challenges to the safe and stable operation of the power grid due to their inherent volatility and uncertainty. Coal-fired power generation, as a key component to ensure national energy security, plays a core role in accepting renewable energy electricity and maintaining the balance of supply and demand in the power grid. In order to more effectively integrate more renewable resources and accelerate the achievement of the dual goals of "carbon emission peak" and "carbon neutrality", traditional coal-fired power generation facilities are changing from being mainly responsible for basic loads to a more flexible operating mode, which means that they need to frequently and deeply adjust the load and be in a state of variable load for a long time. Therefore, it will become a common operation for coal-fired power generation facilities to achieve deep peak regulation and flexible load adjustment. However, existing coal-fired power generation facilities are slow in peak regulation response speed and it is difficult to efficiently respond to rapidly changing load demands. Summary of the invention

[0003] The object of the present invention is to provide a peak-shaving system and operation method of a dual-machine heat recovery unit coupled with a molten salt electric heater, so as to overcome the defects of the coal-fired power generation unit in the prior art that the peak-shaving response is relatively slow and it is difficult to adapt to frequently changing load conditions.

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

[0005] A dual-machine heat recovery unit peak-shaving system coupled with a molten salt electric heater, comprising a thermal system of a coal-fired generator set and a molten salt heat storage system, specifically: the thermal system of the coal-fired generator set comprises a boiler and a main steam turbine system connected thereto, the steam turbine system is coaxially arranged with a first generator, the steam outlet of the steam turbine system is sequentially connected to a condenser, a condensate pump, a low-pressure heater system, a deaerator, a feedwater pump and a high-pressure heater system, the feedwater inlet of the boiler is connected to the feedwater outlet of the high-pressure heater system, the steam inlet of the heat recovery steam turbine system is connected to the steam outlet of the main steam turbine system, the steam inlet of the heat recovery steam turbine system is connected to the steam outlet of the main steam turbine system, the steam inlet of the heat recovery steam turbine system is connected to the steam outlet of the main steam turbine system through a steam regulating valve, the heat recovery steam turbine system is coaxially arranged with a second generator, multiple steam inlets of the low-pressure heater system are connected to multiple steam outlets of the heat recovery steam turbine system, and the final drain outlet of the low-pressure heater system is connected to the drain inlet of the condenser, the steam inlet of the deaerator is connected to the The outlet of a certain stage of the heat recovery steam turbine system is connected, the multiple steam inlets of the high-pressure heater system are connected to the multiple steam outlets of the heat recovery steam turbine system, and the final drain outlet of the high-pressure heater system is connected to the drain inlet of the deaerator; the molten salt heat storage system comprises a molten salt electric heater for heating molten salt, a high-temperature molten salt heat storage tank and a low-temperature molten salt heat storage tank for storing molten salt, and also comprises a low-temperature molten salt pump (15), a high-temperature molten salt pump (16), a high-temperature molten salt heat exchanger (17) and a low-temperature molten salt heat exchanger (18); one end of the low-temperature molten salt pump is connected to the low-temperature molten salt heat storage tank, and the other end is connected to the molten salt electric heater, and is used to transport the low-temperature molten salt to the molten salt electric heater; the high-temperature molten salt pump, one end of which is connected to the high-temperature molten salt heat storage tank, and the other end is connected to the high-temperature molten salt heat exchanger; the high-temperature molten salt heat exchanger is connected in parallel at both ends of the high-pressure heater system, and is used to heat the boiler feed water using the high-temperature molten salt; the low-temperature molten salt heat exchanger is connected in parallel at both ends of the low-pressure heater system, and is used to heat the condensate feed water using the low-temperature molten salt;

[0006] The high-temperature molten salt heat storage tank is connected to the high-temperature molten salt heat exchanger through a high-temperature molten salt regulating valve, and the low-temperature molten salt heat storage tank is connected to the molten salt electric heater through a low-temperature molten salt regulating valve;

[0007] A high-temperature feed water regulating valve is provided between the high-pressure heater system and the high-temperature molten salt heat exchanger, and a low-temperature feed water regulating valve is provided between the low-pressure heater system and the low-temperature molten salt heat exchanger.

[0008] Optionally, the electric energy of the molten salt electric heater comes from the first generator and the second generator, and the electric energy of the second generator is used preferentially.

[0009] The operating method of the dual-machine heat recovery unit peak-shaving system coupled with a molten salt electric heater is as follows: when the thermal system of the coal-fired power generation unit is operating at a low load, the molten salt electric heater is used to heat the low-temperature molten salt when the load of the thermal system of the coal-fired power generation unit is reduced, and store it in a high-temperature molten salt heat storage tank, so that when the load of the thermal system of the coal-fired power generation unit increases, the boiler feed water is heated through the high-temperature molten salt heat exchanger to improve the power generation efficiency and increase the peak-shaving capacity; when the thermal system of the coal-fired power generation unit is operating at a high load, the steam regulating valve is closed, the molten salt electric heater stops using the first generator, the low-temperature feed water regulating valve and the high-temperature feed water regulating valve are opened to bypass the low-temperature condensate and the high-temperature boiler feed water, and the high-temperature molten salt regulating valve and the high-temperature molten salt pump are adjusted to flow into the high-temperature molten salt heat exchanger and the low-temperature molten salt heat exchanger in turn.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] (1) The present invention optimizes the steam flow entering the steam turbine by integrating an external energy storage device, thereby improving the load adjustment speed of the coal-fired power generation unit and enhancing the peak load regulation capability of the coal-fired power generation unit;

[0012] (2) The present invention utilizes a molten salt heat storage system to achieve the decoupling of heat and electricity, further narrowing the power output range of the coal-fired generator set on the basis of the minimum operating load of the boiler, which not only improves the ability of the coal-fired generator set to participate in peak load regulation, but also increases the flexibility of the operation of the coal-fired generator set;

[0013] (3) The present invention uses the electric energy of the main steam turbine system and the heat recovery steam turbine system through the molten salt electric heater, which can assist the peak-shaving operation of the coal-fired power generation unit, reduce the fluctuation of the output power of the heat recovery steam turbine system during the peak-shaving operation of the main engine, and improve the operating stability of the coal-fired power generation unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of a peak-shaving system of a dual-machine heat recovery unit coupled with a molten salt electric heater according to the present invention:

[0015] Description of reference numerals:

[0016] Among them: 1. Boiler; 2. Main steam turbine system; 3. First generator; 4. Condenser; 5. Condensate pump; 6. Low-pressure heater system; 7. Deaerator; 8. Feed water pump; 9. High-pressure heater system; 10. Regenerative steam turbine system; 11. Second generator; 12. Molten salt electric heater; 13. High-temperature molten salt heat storage tank; 14. Low-temperature molten salt heat storage tank; 15. Low-temperature molten salt pump; 16. High-temperature molten salt pump; 17. High-temperature molten salt heat exchanger; 18. Low-temperature molten salt heat exchanger; V1. Steam regulating valve; V2. Low-temperature feed water regulating valve; V3. High-temperature feed water regulating valve; V4. High-temperature molten salt regulating valve; V5. Low-temperature molten salt regulating valve. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the present invention is a dual-machine heat recovery unit peak-shaving system coupled with a molten salt electric heater, including a thermal system of a coal-fired generator set and a molten salt heat storage system, wherein the thermal system of the coal-fired generator set includes: a boiler 1, a main steam turbine system 2 connected thereto, wherein the steam turbine system 2 is coaxially arranged with a first generator 3; the steam outlet of the steam turbine system 2 is sequentially connected to a condenser 4, a condensate pump 5, a low-pressure heater system 6, a deaerator 7, a feed water pump 8 and a high-pressure heater system 9; the feed water inlet of the boiler 1 is connected to the feed water outlet of the high-pressure heater system 9; the steam inlet of the heat recovery turbine system 10 is connected to the steam outlet of the main steam turbine system 2, and the heat recovery turbine system The steam inlet of the main steam turbine system 2 is connected to the steam outlet of the main steam turbine system 2 through a steam regulating valve V1, and the heat recovery steam turbine system 10 is coaxially arranged with the second generator 11; the multiple steam inlets of the low-pressure heater system 6 are connected to the multiple steam outlets of the heat recovery steam turbine system 10, and the last-stage drain outlet of the low-pressure heater system 6 is connected to the drain inlet of the condenser 4; the steam inlet of the deaerator 7 is connected to a certain-stage outlet of the heat recovery steam turbine system 10; the multiple steam inlets of the high-pressure heater system 9 are connected to the multiple steam outlets of the heat recovery steam turbine system 10, and the last-stage drain outlet of the high-pressure heater system 9 is connected to the drain inlet of the deaerator 7;

[0019] The molten salt heat storage system includes: a molten salt electric heater 12 for heating molten salt, a high-temperature molten salt heat storage tank 13 and a low-temperature molten salt heat storage tank 14 for storing molten salt, and also includes a low-temperature molten salt pump 15, a high-temperature molten salt pump 16, a high-temperature molten salt heat exchanger 17 and a low-temperature molten salt heat exchanger 18; the low-temperature molten salt pump 15 is connected at one end to the low-temperature molten salt heat storage tank 14 and at the other end to the molten salt electric heater 12, and is used to transport the low-temperature molten salt to the molten salt electric heater 12; the high-temperature molten salt pump 16 is connected at one end to the high-temperature molten salt heat storage tank 13 and at the other end to the high-temperature molten salt heat exchanger 17; the high-temperature molten salt heat exchanger 17 is connected in parallel at both ends of the high-pressure heater system 9, and is used to heat the boiler 1 feed water using high-temperature molten salt; the low-temperature molten salt heat exchanger 18 is connected in parallel at both ends of the low-pressure heater system 6, and is used to heat the condensate feed water using low-temperature molten salt;

[0020] The high-temperature molten salt heat storage tank 13 is connected to the high-temperature molten salt heat exchanger 17 through a high-temperature molten salt regulating valve V4, and the low-temperature molten salt heat storage tank 14 is connected to the molten salt electric heater 12 through a low-temperature molten salt regulating valve V5;

[0021] A high-temperature feed water regulating valve V3 is provided between the high-pressure heater system 9 and the high-temperature molten salt heat exchanger 17 , and a low-temperature feed water regulating valve V2 is provided between the low-pressure heater system 6 and the low-temperature molten salt heat exchanger 18 .

[0022] Preferably, the electric energy of the molten salt electric heater 12 comes from the first generator 3 and the second generator 11, and the electric energy of the second generator 11 is used preferentially to fully utilize the output of the heat recovery steam turbine system 10, which can reduce the power consumption rate of the power plant and increase the power sales revenue of the power plant.

[0023] like Figure 1 As shown, the operating method of the peak-shaving system of a dual-machine heat recovery unit coupled with a molten salt electric heater described in the present invention is as follows:

[0024] i) When the thermal system of the coal-fired power generation unit is running at a low load, the molten salt electric heater 12 is used to heat the low-temperature molten salt when the load of the thermal system of the coal-fired power generation unit is reduced, and store it in the high-temperature molten salt heat storage tank 13, so as to heat the boiler 1 feed water through the high-temperature molten salt heat exchanger 17 when the load of the thermal system of the coal-fired power generation unit increases, so as to improve the power generation efficiency and increase the peak load regulation capacity;

[0025] ii) When the thermal system of the coal-fired power generation unit is running at high load, the steam regulating valve V1 is closed, the molten salt electric heater 12 stops using the first generator 3, the low-temperature feed water regulating valve V2 and the high-temperature feed water regulating valve V3 are opened to bypass the low-temperature condensate and the high-temperature boiler feed water, and the high-temperature molten salt regulating valve V4 and the high-temperature molten salt pump 16 are adjusted to flow into the high-temperature molten salt heat exchanger 17 and the low-temperature molten salt heat exchanger 18 in turn.

[0026] The molten salt heat storage system of the present invention is provided with two molten salt pumps and two molten salt regulating valves to control the flow of molten salt entering the molten salt electric heater and the molten salt heat exchanger, which can ensure the stable operation of the coal-fired power generation unit during rapid load changes; by adjusting the power of the molten salt electric heater and the working medium flow of the molten salt heat exchanger, the peak-shaving performance of the coal-fired power generation unit can be improved to meet the demand for rapid peak-shaving of the coal-fired power generation unit; the present invention can improve the peak-shaving flexibility of the dual-machine heat recovery coal-fired power generation unit and improve the operating stability of the unit.

Claims

1. A dual-unit heat recovery unit peak load regulation system coupled with a molten salt electric heater, characterized in that: It includes the thermal system of coal-fired power generation units and the molten salt heat storage system, specifically: The thermal system of the coal-fired power generation unit comprises: a boiler (1) and a main steam turbine system (2) connected thereto, wherein the steam turbine system (2) is coaxially arranged with a first generator (3); the steam outlet of the steam turbine system (2) is sequentially connected to a condenser (4), a condensate pump (5), a low-pressure heater system (6), a deaerator (7), a feed water pump (8) and a high-pressure heater system (9); the feed water inlet of the boiler (1) is connected to the feed water outlet of the high-pressure heater system (9); the steam inlet of the heat recovery steam turbine system (10) is connected to the steam outlet of the main steam turbine system (2), and the steam inlet of the heat recovery steam turbine system (10) is connected to the steam outlet of the main steam turbine system (2). The outlets are connected via a steam regulating valve (V1), the heat recovery turbine system (10) and the second generator (11) are arranged coaxially; the multiple steam inlets of the low-pressure heater system (6) are connected to the multiple steam outlets of the heat recovery turbine system (10), and the final stage drain outlet of the low-pressure heater system (6) is connected to the drain inlet of the condenser (4); the steam inlet of the deaerator (7) is connected to a certain stage outlet of the heat recovery turbine system (10); the multiple steam inlets of the high-pressure heater system (9) are connected to the multiple steam outlets of the heat recovery turbine system (10), and the final stage drain outlet of the high-pressure heater system (9) is connected to the drain inlet of the deaerator (7); The molten salt heat storage system comprises: a molten salt electric heater (12) for heating molten salt, a high-temperature molten salt heat storage tank (13) and a low-temperature molten salt heat storage tank (14) for storing molten salt, and also comprises a low-temperature molten salt pump (15), a high-temperature molten salt pump (16), a high-temperature molten salt heat exchanger (17) and a low-temperature molten salt heat exchanger (18); the low-temperature molten salt pump (15) is connected at one end to the low-temperature molten salt heat storage tank (14) and at the other end to the molten salt electric heater (12) for transferring the low-temperature molten salt to the molten salt heat storage tank (14). The salt is transported to the molten salt electric heater (12); the high-temperature molten salt pump (16) is connected at one end to the high-temperature molten salt heat storage tank (13) and at the other end to the high-temperature molten salt heat exchanger (17); the high-temperature molten salt heat exchanger (17) is connected in parallel to both ends of the high-pressure heater system (9) and is used to heat the boiler (1) feed water using the high-temperature molten salt; the low-temperature molten salt heat exchanger (18) is connected in parallel to both ends of the low-pressure heater system (6) and is used to heat the condensate feed water using the low-temperature molten salt; The high-temperature molten salt heat storage tank (13) is connected to the high-temperature molten salt heat exchanger (17) via a high-temperature molten salt regulating valve (V4), and the low-temperature molten salt heat storage tank (14) is connected to the molten salt electric heater (12) via a low-temperature molten salt regulating valve (V5); A high-temperature feed water regulating valve (V3) is provided between the high-pressure heater system (9) and the high-temperature molten salt heat exchanger (17), and a low-temperature feed water regulating valve (V2) is provided between the low-pressure heater system (6) and the low-temperature molten salt heat exchanger (18).

2. A dual-unit heat recovery unit peak load regulation system coupled with a molten salt electric heater according to claim 1, characterized in that: The electric energy of the molten salt electric heater (12) comes from the first generator (3) and the second generator (11), and the electric energy of the second generator (11) is used preferentially.

3. The method for operating a peak-shaving system of a dual-machine heat recovery unit coupled with a molten salt electric heater according to claim 1 or 2, characterized in that: The details are as follows: i) when the thermal system of the coal-fired power generation unit is operating at a low load, the molten salt electric heater (12) is used to heat the low-temperature molten salt when the load of the thermal system of the coal-fired power generation unit is reduced, and store the low-temperature molten salt in the high-temperature molten salt heat storage tank (13), so as to heat the boiler (1) feed water through the high-temperature molten salt heat exchanger (17) when the load of the thermal system of the coal-fired power generation unit increases, so as to improve the power generation efficiency and increase the peak load regulation capacity; ii) When the thermal system of the coal-fired power generation unit is running at high load, the steam regulating valve (V1) is closed, the molten salt electric heater (12) stops using the first generator (3), the low-temperature feed water regulating valve (V2) and the high-temperature feed water regulating valve (V3) are opened to bypass the low-temperature condensate and the high-temperature boiler feed water, and the high-temperature molten salt regulating valve (V4) and the high-temperature molten salt pump (16) are adjusted to flow into the high-temperature molten salt heat exchanger (17) and the low-temperature molten salt heat exchanger (18) in turn.

Images