Steam and fused salt coupled heat storage and release peak shaving system and peak shaving method

Abstract

The invention discloses a steam and fused salt coupled heat storage and release peak shaving system and method. The existing steam sensible heat molten salt heating or pure electric molten salt heating technology has the problems of complex technical process, high construction cost, high implementation difficulty, low system electricity-electricity conversion efficiency and the like. The system comprises a fused salt storage system, a heat storage and exchange system, a heat release and exchange system, boiler equipment and steam turbine equipment, an outlet of the boiler equipment is connected with the steam turbine equipment and the heat storage and exchange system, the fused salt storage system is connected with the heat storage and exchange system and the heat release and exchange system, and the heat release and exchange system is connected with the steam turbine equipment. According to the invention, machine-boiler decoupling and electric heat storage peak regulation of a traditional thermal power plant can be realized. In the heat storage process, latent heat and sensible heat energy of main steam are stored in a fused salt storage system through a heat storage and exchange system, and deep peak regulation and energy storage are achieved; and in the heat release process, heat in the fused salt storage system is released through the heat release heat exchange system, and steam is prepared and supplemented into steam turbine equipment so as to improve the power generation power.

Description

Technical Field

[0001] The present invention relates to the technical fields of deep peak regulation, auxiliary services, energy storage and the like in coal-fired power plants, and in particular to a steam and molten salt coupled heat storage and release peak regulation system and a peak regulation method. Background Art

[0002] With the large-scale access of renewable energy power generation to the grid, the power system faces severe challenges in efficiently absorbing new energy and ensuring safe and stable operation due to the volatility and randomness of new energy resources such as wind and light, and the weak anti-interference and low support of power generation equipment. A high proportion of flexible power sources and energy storage capacity are urgently needed to improve the power structure and ensure the safety of the power grid.

[0003] The deep peak-shaving transformation technology for the main equipment of coal-fired power plants has become mature, and has basically achieved 30%Pe peak-shaving operation. However, due to the differences in the peak-shaving capacity limits of main equipment such as boilers and steam turbines, the actual peak-shaving capacity of coal-fired power plants has not been fully released.

[0004] Molten salt thermal storage and peak-shaving technology is a feasible technical direction for improving the deep peak-shaving capacity of coal-fired power plants and having energy storage properties. However, the existing steam sensible heat heating of molten salt or pure electric heating of molten salt technology has problems such as complex process, high engineering cost, great implementation difficulty, and low system electricity-to-electricity conversion efficiency. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of complex process, high engineering cost, great implementation difficulty and low system electricity-to-electricity conversion efficiency of the existing coal-fired power plant molten salt heat storage and peak-shaving technology system solution, and to provide a steam and molten salt coupled heat storage and release peak-shaving system and a peak-shaving method, which can realize the deep coupling of the steam system of the coal-fired power plant and the steam and molten salt coupled heat storage and release peak-shaving system, and improve the deep peak-shaving capacity and peak-shaving rate of the coal-fired power plant based on high-power and high-temperature heat storage.

[0006] The above purpose is achieved through the following technical solutions: A steam and molten salt coupled heat storage and release peak regulation system, which comprises: a molten salt storage system, a heat storage and heat exchange system, a heat release and heat exchange system, a boiler device and a steam turbine device, wherein the main steam at the outlet of the boiler device is divided into two paths, one of which is connected to the steam turbine device and enters the steam turbine device for expansion and work; The other path is connected to the heat storage and heat exchange system, the water side of the heat storage and heat exchange system is connected to the turbine condensate pipeline, and the heat storage and heat exchange system releases heat to heat the molten salt and part of the feed water and then passes into the condensate pipeline; The heat storage and heat exchange system is connected to the molten salt storage system and is used to heat and store the low-temperature molten salt of the molten salt storage system; The condensate pipeline is connected to the heat release heat exchange system, and the heat release heat exchange system is connected to an extraction pipeline between the high-pressure cylinder of the steam turbine and the check valve of the No. 1 high-pressure steam extraction pipeline, which is used to heat the condensate to prepare steam to enter the steam turbine equipment for expansion and work.

[0007] The heat release and heat exchange system is connected to the molten salt storage system and is used to release heat and store the high-temperature molten salt in the molten salt storage system.

[0008] The described steam and molten salt coupled heat storage and release peak-shaving system, the described heat storage and heat exchange system includes a main steam-molten salt heater, a condenser and a water-molten salt heater, the outlet main steam pipeline of the described boiler equipment enters the main steam-molten salt heater after passing through the main steam extraction pipeline stop valve and the main steam extraction pipeline check valve, the described main steam-molten salt heater is connected to the condenser, the described condenser is connected to the water-molten salt heater, the described water-molten salt heater is connected to the water-water heat exchanger, and the outlet of the described water-water heat exchanger is connected to the condensate pipeline.

[0009] The described steam and molten salt coupled heat storage and release peak-shaving system, the described condensate water pipeline extracts part of the feed water from the outlet of the feed water pump, enters the water-water heat exchanger through the feed water heating bypass pipeline to absorb the heat of the main steam condensate, and then returns to the feed water pipeline between the No. 1 high-pressure heater and the boiler.

[0010] The steam and molten salt coupled heat storage and release peak-shaving system, the molten salt storage system comprises a low-temperature molten salt storage tank and a molten salt electric heater; The low-temperature molten salt storage tank is pumped out with a low-temperature molten salt pump and is divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve. One path is connected to the water-molten salt heater, enters the water-molten salt heater to absorb the heat of the main steam condensation water and becomes medium-temperature molten salt, then enters the condenser to absorb the latent heat released by the main steam and becomes medium-high temperature molten salt, then enters the main steam-molten salt heater to absorb the sensible heat released by the main steam and becomes high-temperature molten salt, and then enters the high-temperature molten salt storage tank through the high-temperature molten salt storage tank inlet stop valve for storage.

[0011] The described steam and molten salt coupled heat storage and release peak-shaving system, the described low-temperature molten salt storage tank is pumped out with a low-temperature molten salt pump and is divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve, the other path is connected to the molten salt electric heater, the low-temperature molten salt enters the molten salt electric heater through the molten salt electric heating bypass flow regulating valve, and after being converted into high-temperature molten salt, it enters the high-temperature molten salt storage tank through the high-temperature molten salt storage tank inlet stop valve for storage.

[0012] The described steam and molten salt coupled heat storage and release peak-shaving system, the described heat release heat exchange system includes a superheater, an evaporator, a preheater and a molten salt-feedwater heater, the described high-temperature molten salt storage tank is connected with the superheater, and the high-temperature molten salt is extracted from the high-temperature molten salt storage tank by a high-temperature molten salt pump and enters the superheater through the high-temperature molten salt storage tank outlet stop valve, the described superheater is connected with the evaporator, after releasing heat through the superheater, it enters the evaporator to heat the saturated water to generate steam to become medium-temperature molten salt, and then enters the preheater to heat the supercooled water to become sub-medium-temperature molten salt, and then enters the molten salt-feedwater heater to heat the constant temperature feedwater to become low-temperature molten salt, and enters the low-temperature molten salt storage tank through the low-temperature molten salt storage tank inlet stop valve for storage.

[0013] The described steam and molten salt coupled heat storage and release peak-shaving system, the described feed water pump outlet pipeline is connected with the feed water pump outlet mixed water pipeline, part of the feed water extracted by the feed water pump passes through the feed water pump outlet mixed water bypass stop valve and is mixed with part of the feed water extracted from the No. 2 high-pressure heater outlet after passing through the No. 2 high-pressure heater outlet mixed water bypass stop valve and the No. 2 high-pressure heater outlet mixed water bypass regulating valve, the mixed constant temperature feed water enters the molten salt-feed water heater all the way and is heated by the sub-medium temperature molten salt, and then returns to the feed water pipeline between the No. 1 high-pressure heater and the boiler through the molten salt-feed water heater outlet stop valve.

[0014] The described steam and molten salt coupled heat storage and release peak regulation system, the described mixed constant temperature feed water another route passes through the steam generation system inlet regulating valve and then enters the preheater to absorb the heat of medium-temperature molten salt to become saturated water, then enters the evaporator to absorb the heat of medium-high temperature molten salt to become saturated steam, then enters the superheater to absorb the heat of high-temperature molten salt to become superheated steam, then passes through the steam supply pipeline stop valve, the steam supply pipeline check valve, the steam supply pipeline regulating valve in sequence, and then enters an extraction pipeline between the high-pressure cylinder of the steam turbine and the check valve of the No. 1 high-pressure steam extraction pipeline.

[0015] The steam and molten salt coupled heat storage and release peak-shaving system, the boiler equipment is a boiler.

[0016] The steam and molten salt coupled heat storage and release peak-shaving system, the steam turbine equipment includes a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine high-pressure regulating valve, a deaerator, a feed water pump, No. 3 high-pressure heater, No. 2 high-pressure heater, No. 1 high-pressure heater, and a check valve for the steam extraction pipeline of No. 1 high-pressure heater.

[0017] A peak regulation method for a steam and molten salt coupled heat storage and release peak regulation system, the method comprising the following steps: a high-pressure regulating valve of a steam turbine and a check valve of a No. 1 high-pressure heater extraction steam pipeline are always kept in an open state; (1) During the heat storage process, the stop valve of the main steam extraction pipeline is opened, the check valve of the main steam extraction pipeline is opened, the stop valve of the main steam drain pipeline is opened, the main steam drain pipeline regulating valve is opened, the feed water heating bypass stop valve is opened, the feed water heating bypass regulating valve is opened, the feed water heating bypass heater outlet stop valve is opened, the low temperature molten salt storage tank outlet stop valve is opened, the high temperature molten salt storage tank inlet stop valve is opened, the molten salt electric heating bypass flow regulating valve is opened, and the other valves are in the closed state; (2) During the heat storage process, the main steam-molten salt heater, condenser, and water-molten salt heater are in the lowest steady-state load to full-load operation state, and the low-temperature molten salt pump is used to control the molten salt flow rate and the main steam extraction flow rate in the main steam-molten salt heater, condenser, and water-molten salt heater. The water-water heat exchanger is in the lowest steady-state load to full-load operation state, and the feed water heating bypass regulating valve is used to adjust the water-water heat exchanger feed water outlet temperature and the main steam condensate outlet temperature; (3) During the heat storage process, the molten salt electric heater is in a state of operation from the lowest steady-state load to full load, and the molten salt electric heating bypass flow regulating valve is used to control the power of the molten salt electric heater; (4) During the heat storage process, the low-temperature molten salt in the low-temperature molten salt storage tank is heated up to become high-temperature molten salt and then enters the high-temperature molten salt storage tank for storage; (5) During the heat release process, the stop valve of the steam supply pipe is opened, the check valve of the steam supply pipe is opened, the regulating valve of the steam supply pipe is opened, the stop valve of the mixed water bypass at the outlet of the feedwater pump is opened, the stop valve of the mixed water bypass at the outlet of the No. 2 high-pressure heater is opened, the regulating valve of the mixed water bypass at the outlet of the No. 2 high-pressure heater is opened, the regulating valve of the steam generation system inlet is opened, the stop valve of the molten salt-feedwater heater outlet is opened, the stop valve of the low-temperature molten salt storage tank inlet is opened, the stop valve of the high-temperature molten salt storage tank outlet is opened, and the other valves are closed; (6) During the heat release process, the superheater, evaporator, and preheater are in the lowest steady-state load to full-load operation state. The high-temperature molten salt pump is used to control the molten salt flow rate, steam production, and evaporator molten salt side pressure in the superheater, evaporator, and preheater. The steam generation system inlet regulating valve is used to control the evaporator liquid level and the evaporator steam-water side pressure. The molten salt-feedwater heater is in the lowest steady-state load to full-load operation state. The No. 2 high-pressure outlet mixed water bypass regulating valve is used to control the feedwater flow rate and the molten salt temperature at the outlet of the molten salt-feedwater heater. The steam supply pipeline regulating valve is used to control the amount of steam supplied to the first extraction pipeline; (7) During the heat release process, the high-temperature molten salt in the high-temperature molten salt storage tank cools down and becomes low-temperature molten salt, which then enters the low-temperature molten salt storage tank for storage. Beneficial Effects

[0018] 1. The present invention adopts a dual-path heating design, and performs flexible steam "sensible heat + latent heat" heat storage and electric heating heat storage through the configuration of different main steam extraction volumes and electric heating powers, which can achieve a 5% to 15%Pe deep peak-shaving capacity improvement in coal-fired power plants, among which the peak-shaving capacity that can be improved by single main steam extraction is 6.28%Pe.

[0019] 2. The heat exchanger of the heat storage and heat exchange system of the present invention can maintain a minimum load operating state of 15% under rated parameters and can reach a full load operating state within 2 minutes. The peak load rate (load reduction) of a single-unit equipment can be increased by 2.67% Pe / min through main steam extraction and heat storage.

[0020] 3. The heat release heat exchange system of the present invention adopts a steam supplement design for the steam turbine thermal system. By supplementing a fixed amount of steam, it can provide a fixed capacity support of 3.85% to 5.96% Pe in different operating load ranges of the steam turbine.

[0021] 4. The heat exchanger of the heat release heat exchange system of the present invention can maintain a minimum load operation state of 15% under rated parameters, and can reach a full load operation state within 2 minutes. The peak load rate (load increase) of a single unit can be increased by 1.64% Pe / min through steam supplementation in the turbine thermal system.

[0022] 5. The present invention achieves a relatively high electricity-to-electricity conversion efficiency, that is, the ratio of the additional power generation generated by the steam added to the system during the heat release process to the power generation lost due to main steam extraction and electric heating during the heat storage process. In the peak load regulation capacity range of 5% to 15% Pe, the electricity-to-electricity conversion efficiency can reach 50.55% to 69.66%.

[0023] 6. The exothermic heat exchange system of the present invention is used for steam preparation, and the steam pressure is adjustable, which can adapt to the pressure variation range of 1.5~8.0MPa and the steam supply flow rate variation of ≤50t / h. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the present invention; In the figure: 1-1, low temperature molten salt storage tank; 1-2, high temperature molten salt storage tank; 1-3, low temperature molten salt pump; 1-4, low temperature molten salt storage tank outlet stop valve; 1-5, low temperature molten salt storage tank inlet stop valve; 1-6, high temperature molten salt storage tank inlet stop valve; 1-7, high temperature molten salt pump; 1-8, high temperature molten salt storage tank outlet stop valve; 1-9, molten salt electric heating bypass flow regulating valve; 1-10, molten salt electric heater; 2-1, main steam-molten salt heater; 2-2, condenser ; 2-3, water-molten salt heater; 2-4, water-water heat exchanger; 2-5, main steam extraction pipeline stop valve; 2-6, main steam extraction pipeline check valve; 2-7, main steam drain pipeline stop valve; 2-8, main steam drain pipeline regulating valve; 2-9, feed water heating bypass stop valve; 2-10, feed water heating bypass regulating valve; 2-11, feed water heating bypass heater outlet stop valve; 2-12, main steam drain pipeline; 2-13, feed water heating bypass pipeline ;3-1, superheater;3-2, evaporator;3-3, preheater;3-4, molten salt-feedwater heater;3-5, steam supply pipe stop valve;3-6, steam supply pipe check valve;3-7, steam supply pipe regulating valve;3-8, feedwater pump outlet mixed water bypass stop valve;3-9, No. 2 high pressure heater outlet mixed water bypass stop valve;3-10, No. 2 high pressure heater outlet mixed water bypass regulating valve;3-11, steam generation system inlet regulating valve;3-12, molten salt-feedwater heater outlet 1. Stop valve; 3-13. Feedwater pump outlet mixed water pipe; 3-14. No. 2 high pressure heater outlet mixed water bypass pipe; 4. Boiler; 5-1. Turbine high pressure cylinder; 5-2. Turbine medium pressure cylinder; 5-3. Turbine high pressure control valve; 5-4. Deaerator; 5-5. Feedwater pump; 5-6. No. 3 high pressure heater; 5-7. No. 2 high pressure heater; 5-8. No. 1 high pressure heater; 5-9. No. 1 high pressure heater extraction pipe check valve; 5-10. Extraction pipe; 6. Feedwater pipe; 7. Condensate pipe. DETAILED DESCRIPTION

[0025] Reference Figure 1 A steam and molten salt coupled heat storage and release peak regulation system, which comprises: a molten salt storage system, a heat storage and heat exchange system, a heat release and heat exchange system, a boiler device 4 and a steam turbine device, wherein the main steam at the outlet of the boiler device is divided into two paths, one of which is connected to the steam turbine device and enters the steam turbine device for expansion and work; The main steam at the outlet of boiler 4 is divided into two paths. One path of steam enters the high-pressure cylinder 5-1 of the steam turbine through the high-pressure regulating valve 5-3 of the steam turbine to expand and do work. Part of the steam is extracted and enters the first extraction pipe 5-10. After passing through the check valve 5-9 of the No. 1 high-pressure heater extraction pipe, it enters the No. 1 high-pressure heater 5-8. After the remaining steam is discharged from the high-pressure cylinder 5-1 of the steam turbine, part of the steam is extracted and enters the No. 2 high-pressure heater 5-7 through the second extraction pipe. The remaining steam enters the boiler 4 for reheating and then enters the turbine intermediate-pressure cylinder 5-2. After expanding and doing work, part of the steam is extracted and enters the No. 3 high-pressure heater 5-6 through the third extraction pipe. The remaining steam continues to expand and do work, and part of the steam is extracted and enters the deaerator 5-4 through the fourth extraction pipe.

[0026] Another steam path is connected to the heat storage and heat exchange system, and the heat storage and heat exchange system is connected to the condensate water pipeline 7. The heat is released by the heat storage and heat exchange system to heat the molten salt and part of the feed water and then enter the condensate water pipeline 7.

[0027] The heat storage and heat exchange system is connected to the molten salt storage system and is used to heat and store the low-temperature molten salt of the heat storage and heat exchange system; The condensate pipe 7 is connected to the heat release heat exchange system, and the heat release heat exchange system is connected to the first extraction pipe 5-10 between the high-pressure cylinder 5-1 of the steam turbine and the check valve 5-9 of the No. 1 high-pressure steam extraction pipe, and is used to heat the condensate to prepare steam to enter the steam turbine equipment for expansion and work; The heat storage and heat exchange system comprises a main steam-molten salt heater 2-1, a condenser 2-2 and a water-molten salt heater 2-3. The outlet main steam pipeline of the boiler equipment enters the main steam-molten salt heater 2-1 after passing through the main steam extraction pipeline stop valve 2-5 and the main steam extraction pipeline check valve 2-6 to release sensible heat to heat the high-temperature molten salt, and then enters the condenser 2-2 to release latent heat to heat the medium-temperature molten salt, and then condenses into water and enters the water-molten salt heater 2-3 to release heat to heat the low-temperature molten salt, and then enters the water-water heat exchanger 2-4 to release heat to heat part of the feed water, and then passes through the main steam drain pipeline stop valve 2-7 and the main steam drain pipeline regulating valve 2-8 to replenish the condensate pipeline 7 before the deaerator 5-4; The condensate pipe 7 extracts part of the feed water from the outlet of the feed water pump 5-5, enters the water-water heat exchanger 2-4 through the feed water heating bypass pipe 2-13 to absorb the main steam drainage heat, and then returns to the feed water pipe 6 between the No. 1 high pressure heater 5-8 and the boiler 4.

[0028] The molten salt storage system includes a low-temperature molten salt storage tank 1-1, a high-temperature molten salt storage tank 1-2 and a molten salt electric heater 1-10.

[0029] The low-temperature molten salt storage tank 1-1 extracts low-temperature molten salt through the low-temperature molten salt pump 1-3 and is divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve 1-4. One path is connected to the water-molten salt heater 2-3, enters the water-molten salt heater 2-3 to absorb the heat of the main steam condensation water and becomes medium-temperature molten salt, then enters the condenser 2-2 to absorb the latent heat released by the main steam and becomes medium-high temperature molten salt, then enters the main steam-molten salt heater 2-1 to absorb the sensible heat released by the main steam and becomes high-temperature molten salt, and then enters the high-temperature molten salt storage tank 1-2 for storage through the high-temperature molten salt storage tank inlet stop valve 1-6.

[0030] The low-temperature molten salt storage tank 1-1 extracts low-temperature molten salt through the low-temperature molten salt pump 1-3 and is divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve 1-4. The other path is connected to the molten salt electric heater 1-10. The low-temperature molten salt enters the molten salt electric heater 1-10 through the molten salt electric heating bypass flow regulating valve 1-9, and after becoming high-temperature molten salt, it enters the high-temperature molten salt storage tank 1-2 for storage through the high-temperature molten salt storage tank inlet stop valve 1-6.

[0031] The exothermic heat exchange system includes a superheater 3-1, an evaporator 3-2, a preheater 3-3 and a molten salt-feedwater heater 3-4. The high-temperature molten salt storage tank 1-2 is connected to the superheater 3-1. The high-temperature molten salt drawn from the high-temperature molten salt storage tank 1-2 by the high-temperature molten salt pump 1-7 enters the superheater 3-1 through the high-temperature molten salt storage tank outlet stop valve 1-8 to heat the steam to become medium-high temperature molten salt. After releasing heat in the superheater 3-1, it enters the evaporator 3-2 to heat the saturated water to generate steam to become medium-temperature molten salt, and then enters the preheater 3-3 to heat the supercooled water to become sub-medium temperature molten salt, and then enters the molten salt-feedwater heater 3-4 to heat the constant temperature feedwater to become low-temperature molten salt, and enters the low-temperature molten salt storage tank 1-1 through the low-temperature molten salt storage tank inlet stop valve 1-5 for storage.

[0032] The outlet pipeline of the feed water pump 5-5 is connected with the feed water pump outlet mixed water pipeline 3-13. Part of the feed water drawn out by the feed water pump 5-5 passes through the feed water pump outlet mixed water bypass stop valve 3-8 and is mixed with part of the feed water drawn out from the outlet of No. 2 high pressure heater 5-7 after passing through the No. 2 high pressure heater outlet mixed water bypass stop valve 3-9 and the No. 2 high pressure heater outlet mixed water bypass regulating valve 3-10. The mixed constant temperature feed water enters the molten salt-feed water heater 3-4 and is heated by the sub-medium temperature molten salt, and then returns to the feed water pipeline 6 between No. 1 high pressure heater 5-8 and the boiler 4 through the molten salt-feed water heater outlet stop valve 3-12.

[0033] The mixed constant temperature feed water passes through the steam generation system inlet regulating valve 3-11 and then enters the preheater 3-3 to absorb the heat of medium-temperature molten salt and becomes saturated water, then enters the evaporator 3-2 to absorb the heat of medium-high temperature molten salt and becomes saturated steam, then enters the superheater 3-1 to absorb the heat of high-temperature molten salt and becomes superheated steam, then passes through the steam supply pipeline stop valve 3-5, the steam supply pipeline check valve 3-6, the steam supply pipeline regulating valve 3-7 in turn, and then enters the first extraction pipeline 5-10 between the turbine high-pressure cylinder 5-1 and the No. 1 high-pressure steam extraction pipeline check valve 5-9.

[0034] The steam and molten salt coupled heat storage and release peak-shaving system proposed in the invention can transform the original traditional coal-fired power plant into an ultra-flexible peak-shaving power plant with energy storage properties by adding a molten salt storage system, a heat storage and heat exchange system, and a heat release and heat exchange system.

[0035] The boiler equipment is a boiler 4 .

[0036] The steam turbine equipment includes a steam turbine high-pressure cylinder 5-1, a steam turbine intermediate-pressure cylinder 5-2, a steam turbine high-pressure regulating valve 5-3, a deaerator 5-4, a feed water pump 5-5, a No. 3 high-pressure heater 5-6, a No. 2 high-pressure heater 5-7, a No. 1 high-pressure heater 5-8, a No. 1 high-pressure heater extraction pipe check valve 5-9, and an extraction pipe 5-10.

[0037] A peak regulation method for a steam and molten salt coupled heat storage and release peak regulation system, the method comprising the following steps: The turbine high-pressure regulating valve 5-3 and the No. 1 high-pressure steam extraction pipeline check valve 5-9 are always kept in the open state.

[0038] During the heat storage process, the main steam extraction pipeline stop valve 2-5 is opened, the main steam extraction pipeline check valve 2-6 is opened, the main steam drain pipeline stop valve 2-7 is opened, the main steam drain pipeline regulating valve 2-8 is opened, the feed water heating bypass stop valve 2-9 is opened, the feed water heating bypass regulating valve 2-10 is opened, the feed water heating bypass heater outlet stop valve 2-11 is opened, the low-temperature molten salt storage tank outlet stop valve 1-4 is opened, the high-temperature molten salt storage tank inlet stop valve 1-6 is opened, the molten salt electric heating bypass flow regulating valve 1-9 is opened, and the other valves are in the closed state.

[0039] During the heat storage process, the main steam-molten salt heater 2-1, the condenser 2-2, and the water-molten salt heater 2-3 are in the lowest steady-state load to full-load operation state, and the low-temperature molten salt pump 1-3 is used to control the molten salt flow and the main steam extraction flow in the main steam-molten salt heater 2-1, the condenser 2-2, and the water-molten salt heater 2-3. The water-water heat exchanger 2-4 is in the lowest steady-state load to full-load operation state, and the feed water heating bypass regulating valve 2-10 is used to adjust the feed water outlet temperature of the water-water heat exchanger 2-4 and the main steam condensate outlet temperature. This implementation process stores the sensible heat and latent heat of the main steam.

[0040] During the heat storage process, the molten salt electric heater 1-10 is in a state of operation from the lowest steady-state load to full load, and the molten salt electric heating bypass flow regulating valve 1-9 is used to control the power of the molten salt electric heater 1-10. This implementation process stores electrical energy heat.

[0041] During the heat storage process, the low-temperature molten salt in the low-temperature molten salt storage tank 1-1 is heated up to become high-temperature molten salt and then enters the high-temperature molten salt storage tank 1-2 for storage.

[0042] During the heat release process, the steam supply pipeline stop valve 3-5 is opened, the steam supply pipeline check valve 3-6 is opened, the steam supply pipeline regulating valve 3-7 is opened, the feed water pump outlet mixed water bypass stop valve 3-8 is opened, the No. 2 high-pressure heater outlet mixed water bypass stop valve 3-9 is opened, the No. 2 high-pressure heater outlet mixed water bypass regulating valve 3-10 is opened, the steam generation system inlet regulating valve 3-11 is opened, the molten salt-feed water heater outlet stop valve 3-12 is opened, the low-temperature molten salt storage tank inlet stop valve 1-5 is opened, the high-temperature molten salt storage tank outlet stop valve 1-8 is opened, and the other valves are in the closed state.

[0043] During the heat release process, the superheater 3-1, evaporator 3-2, and preheater 3-3 are in the lowest steady-state load to full-load operation state, and the high-temperature molten salt pump 1-7 is used to control the molten salt flow, steam production, and evaporator 3-3 pressure in the superheater 3-1, evaporator 3-2, and preheater 3-3. The steam generation system inlet regulating valve 3-11 is used to control the evaporator 3-2 liquid level and evaporator 3-3 pressure. The molten salt-feedwater heater 3-4 is in the lowest steady-state load to full-load operation state, and the No. 2 high-pressure outlet mixed water bypass regulating valve 3-10 is used to control the feedwater flow and the molten salt temperature at the outlet of the molten salt-feedwater heater 3-4. The steam supply pipeline regulating valve 3-7 is used to control the amount of steam added to the first extraction pipeline. This implementation process releases the heat of molten salt.

[0044] During the heat release process, the high-temperature molten salt in the high-temperature molten salt storage tank 1-2 is cooled down to become low-temperature molten salt and then enters the low-temperature molten salt storage tank 1-1 for storage.

[0045] The present invention realizes the "machine-boiler decoupling" and electric heat storage peak-shaving of traditional thermal power plants through a steam-molten salt coupled heat storage and release peak-shaving system, thereby expanding the peak-shaving depth and peak-shaving rate of thermal power units. During the heat storage process, the main steam latent heat and sensible heat electric energy are stored by molten salt heat exchange, which greatly improves the heat storage energy and heat storage quality. During the heat release process, the power generation capacity is increased by the most direct system steam supplement. The present invention improves the upper and lower limits of the power generation capacity and the variable load rate during peak and valley periods of the unit through a steam-molten salt coupled heat storage and release peak-shaving system, and has a high electricity-to-electricity conversion efficiency.

Claims

1. A steam and molten salt coupled heat storage and release peak regulation system, comprising: The molten salt storage system, the heat storage and heat exchange system, the heat release and heat exchange system, the boiler equipment and the steam turbine equipment are characterized in that: the main steam at the outlet of the boiler equipment is divided into two paths, one of which is connected to the steam turbine equipment and enters the steam turbine equipment to expand and do work; The other path is connected to the heat storage and heat exchange system, the water side of the heat storage and heat exchange system is connected to the turbine condensate pipeline, and the heat storage and heat exchange system releases heat to heat the molten salt and part of the feed water and then passes into the condensate pipeline; The heat storage and heat exchange system is connected to the molten salt storage system and is used to heat and store the low-temperature molten salt of the molten salt storage system; The condensate pipeline is connected to the heat release heat exchange system, and the heat release heat exchange system is connected to a steam turbine high-pressure cylinder and a steam extraction pipeline between the check valve of the No. 1 high-pressure heater extraction pipeline, and is used to heat the condensate to prepare steam to enter the steam turbine equipment for expansion and work; The heat release and heat exchange system is connected to the molten salt storage system and is used to release heat and store the high-temperature molten salt in the molten salt storage system.

2. According to claim 1, a steam and molten salt coupled heat storage and release peak shaving system is characterized by: The heat storage and heat exchange system includes a main steam-molten salt heater, a condenser and a water-molten salt heater. The outlet main steam pipeline of the boiler equipment enters the main steam-molten salt heater after passing through the main steam extraction pipeline stop valve and the main steam extraction pipeline check valve. The main steam-molten salt heater is connected to the condenser, the condenser is connected to the water-molten salt heater, the water-molten salt heater is connected to the water-water heat exchanger, and the outlet of the water-water heat exchanger is connected to the condensate pipeline.

3. A steam and molten salt coupled heat storage and release peak shaving system according to claim 2, characterized in that: The condensate pipe extracts part of the feed water from the outlet of the feed water pump, enters the water-water heat exchanger through the feed water heating bypass pipe to absorb the heat of the main steam condensate, and then returns to the feed water pipe between the No. 1 high pressure heater and the boiler.

4. The steam and molten salt coupled heat storage and release peak shaving system according to claim 3 is characterized by: The molten salt storage system comprises a low-temperature molten salt storage tank, a high-temperature molten salt storage tank and a molten salt electric heater; The low-temperature molten salt storage tank is pumped out with a low-temperature molten salt pump and is divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve. One path is connected to the water-molten salt heater, enters the water-molten salt heater to absorb the heat of the main steam condensation water and becomes medium-temperature molten salt, then enters the condenser to absorb the latent heat released by the main steam and becomes medium-high temperature molten salt, then enters the main steam-molten salt heater to absorb the sensible heat released by the main steam and becomes high-temperature molten salt, and then enters the high-temperature molten salt storage tank through the high-temperature molten salt storage tank inlet stop valve for storage.

5. The steam and molten salt coupled heat storage and release peak shaving system according to claim 3 is characterized by: The low-temperature molten salt storage tank is pumped out with a low-temperature molten salt pump and divided into two paths after passing through the low-temperature molten salt storage tank outlet stop valve. The other path is connected to the molten salt electric heater, and the low-temperature molten salt enters the molten salt electric heater through the molten salt electric heating bypass flow regulating valve. After becoming high-temperature molten salt, it enters the high-temperature molten salt storage tank through the high-temperature molten salt storage tank inlet stop valve for storage.

6. The steam and molten salt coupled heat storage and release peak shaving system according to claim 1 is characterized in that: The exothermic heat exchange system includes a superheater, an evaporator, a preheater and a molten salt-feedwater heater. The high-temperature molten salt storage tank is connected to the superheater. The high-temperature molten salt is pumped out from the high-temperature molten salt storage tank by a high-temperature molten salt pump and enters the superheater through the high-temperature molten salt storage tank outlet stop valve. The superheater is connected to the evaporator. After releasing heat in the superheater, it enters the evaporator to heat the saturated water to generate steam to become medium-temperature molten salt, and then enters the preheater to heat the supercooled water to become sub-medium-temperature molten salt, and then enters the molten salt-feedwater heater to heat the constant temperature feedwater to become low-temperature molten salt, and enters the low-temperature molten salt storage tank through the low-temperature molten salt storage tank inlet stop valve for storage.

7. The steam and molten salt coupled heat storage and release peak shaving system according to claim 6 is characterized by: The feed water pump outlet pipeline is connected with the feed water pump outlet mixed water pipeline. Part of the feed water drawn out by the feed water pump passes through the feed water pump outlet mixed water bypass stop valve and is mixed with part of the feed water drawn out from the No. 2 high-pressure heater outlet after passing through the No. 2 high-pressure heater outlet mixed water bypass stop valve and the No. 2 high-pressure heater outlet mixed water bypass regulating valve. The mixed constant temperature feed water enters the molten salt-feed water heater all the way and is heated by the sub-medium temperature molten salt, and then returns to the feed water pipeline between the No. 1 high-pressure heater and the boiler through the molten salt-feed water heater outlet stop valve.

8. The steam and molten salt coupled heat storage and release peak shaving system according to claim 6 is characterized by: The mixed constant temperature feed water passes through the steam generation system inlet regulating valve and then enters the preheater to absorb the heat of medium-temperature molten salt to become saturated water, then enters the evaporator to absorb the heat of medium- and high-temperature molten salt to become saturated steam, then enters the superheater to absorb the heat of high-temperature molten salt to become superheated steam, then passes through the steam supply pipeline stop valve, the steam supply pipeline check valve, and the steam supply pipeline regulating valve in sequence and enters an extraction pipeline between the high-pressure cylinder of the steam turbine and the check valve of the No. 1 high-pressure steam extraction pipeline.

9. The steam and molten salt coupled heat storage and release peak shaving system according to claim 1 is characterized by: The boiler equipment is a boiler.

10. A peak-shaving method for a steam and molten salt coupled heat storage and release peak-shaving system according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: the high-pressure regulating valve of the steam turbine and the check valve of the No. 1 high-pressure steam extraction pipeline are always kept in an open state; (1) During the heat storage process, the stop valve of the main steam extraction pipeline is opened, the check valve of the main steam extraction pipeline is opened, the stop valve of the main steam drain pipeline is opened, the main steam drain pipeline regulating valve is opened, the feed water heating bypass stop valve is opened, the feed water heating bypass regulating valve is opened, the feed water heating bypass heater outlet stop valve is opened, the low temperature molten salt storage tank outlet stop valve is opened, the high temperature molten salt storage tank inlet stop valve is opened, the molten salt electric heating bypass flow regulating valve is opened, and the other valves are in the closed state; (2) During the heat storage process, the main steam-molten salt heater, condenser, and water-molten salt heater are in the lowest steady-state load to full-load operation state, and the low-temperature molten salt pump is used to control the molten salt flow rate and the main steam extraction flow rate in the main steam-molten salt heater, condenser, and water-molten salt heater. The water-water heat exchanger is in the lowest steady-state load to full-load operation state, and the feed water heating bypass regulating valve is used to adjust the water-water heat exchanger feed water outlet temperature and the main steam condensate outlet temperature; (3) During the heat storage process, the molten salt electric heater is in a state of operation from the lowest steady-state load to full load, and the salt electric heating bypass flow regulating valve is used to control the power of the molten salt electric heater; (4) During the heat storage process, the low-temperature molten salt in the low-temperature molten salt storage tank is heated up to become high-temperature molten salt and then enters the high-temperature molten salt storage tank for storage; (5) During the heat release process, the stop valve of the steam supply pipe is opened, the check valve of the steam supply pipe is opened, the regulating valve of the steam supply pipe is opened, the stop valve of the mixed water bypass at the outlet of the feedwater pump is opened, the stop valve of the mixed water bypass at the outlet of the No. 2 high-pressure heater is opened, the regulating valve of the mixed water bypass at the outlet of the No. 2 high-pressure heater is opened, the regulating valve of the steam generation system inlet is opened, the stop valve of the molten salt-feedwater heater outlet is opened, the stop valve of the low-temperature molten salt storage tank inlet is opened, the stop valve of the high-temperature molten salt storage tank outlet is opened, and the other valves are closed; (6) During the heat release process, the superheater, evaporator, and preheater are in the lowest steady-state load to full-load operation state. The high-temperature molten salt pump is used to control the molten salt flow rate, steam production, and evaporator molten salt side pressure in the superheater, evaporator, and preheater. The steam generation system inlet regulating valve is used to control the evaporator liquid level and the evaporator steam-water side pressure. The molten salt-feedwater heater is in the lowest steady-state load to full-load operation state. The No. 2 high-pressure outlet mixed water bypass regulating valve is used to control the feedwater flow rate and the molten salt temperature at the outlet of the molten salt-feedwater heater. The steam supply pipeline regulating valve is used to control the amount of steam supplied to the first extraction pipeline; (7) During the heat release process, the high-temperature molten salt in the high-temperature molten salt storage tank cools down and becomes low-temperature molten salt, which then enters the low-temperature molten salt storage tank for storage.

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