Heat supply system and heat supply method for coupling coal-fired boiler with fused salt heat storage

Abstract

The invention provides a heat supply system and method for coupling a coal-fired boiler with fused salt heat storage, and relates to the technical field of coal chemical industry heat supply. The heat supply system comprises a hot molten salt tank used for storing hot molten salt; the cold molten salt tank is used for storing cold molten salt; the fused salt heater is used for converting the electric energy into heat energy, heating the cold fused salt into hot fused salt by using the heat energy, and storing the hot fused salt into the hot fused salt tank; the cold fused salt exchanges heat with steam sent out by the coal-fired boiler in the fused salt heat exchanger, and the cold fused salt becomes hot fused salt after absorbing heat of the steam and enters the hot fused salt tank; and the auxiliary generating device comprises a steam generator, demineralized water is heated through heat energy of the hot molten salt to generate auxiliary steam to be supplied to a steam main pipe of the coal-fired boiler, and the hot molten salt becomes cold molten salt through heat loss and enters the cold molten salt tank. According to the heat supply system and the heat supply method, the problem that reliable steam heat supply cannot be provided in time when sudden accidents such as sudden fire extinguishing of a boiler or sudden tripping of chemical equipment occur in a coal chemical system in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal chemical heating, and in particular to a heating system of a coal-fired boiler coupled with molten salt heat storage and a heating method of a coal-fired boiler coupled with molten salt heat storage. Background Art

[0002] At present, the heating systems of coal chemical enterprises mostly use multiple large-capacity coal-fired units, equipped with back-pressure steam turbines or extraction back-pressure steam turbines and generators to provide high-pressure and low-pressure steam required for coal chemical production; under the start-up operation condition, the steam demand is large, and all coal-fired units are in operation; under normal operation conditions, the coal chemical system equipment achieves steam self-balancing, the steam demand drops significantly, and some coal-fired boilers are stopped; in order to reduce the idle rate of boilers, coal chemical enterprises change some large equipment from electric drive to steam drive, increase steam consumption, and add small back pressure machines to achieve steam rebalancing. However, due to the special process of chemical enterprises, a certain amount of steam is required for reliable standby under accident conditions, otherwise there is a risk of expanding the accident.

[0003] In order to meet the pipeline purging requirements of the start-up operation conditions, multiple large-capacity boilers need to be configured to meet the steam volume. When the pipeline purging is completed and the coal chemical system enters the normal operation condition, the coal chemical production chain steam achieves self-balance, the steam demand decreases, and the boiler is stopped for a long time, resulting in a high equipment idle rate and reduced investment benefits. At the same time, in order to prevent the sudden extinguishing of the running boiler or the tripping of the chemical equipment, which will cause the steam gap to further expand, a certain amount of steam source needs to be provided at any time, but the boiler starts up. It takes a certain amount of time and cannot respond to emergency conditions, which will inevitably cause the boiler to maintain low-load operation for a long time, resulting in a decrease in boiler thermal efficiency, an increase in coal consumption, and a decrease in heating safety and reliability.

[0004] Therefore, there is an urgent need for a device that can solve at least one of the above problems. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a heating system and a heating method of a coal-fired boiler coupled with molten salt heat storage, which is used to solve the problem in the prior art that reliable steam heating cannot be provided in time when sudden accidents such as sudden boiler fire extinguishing or sudden tripping of chemical equipment occur in the coal chemical system.

[0006] In order to achieve the above object, the present invention provides a heating system of a coal-fired boiler coupled with molten salt heat storage, which is used to supply heat to a coal chemical system. The heating system comprises: Hot molten salt tank, used to store hot molten salt; A cold molten salt tank, used for storing cold molten salt; The molten salt heater is connected between the cold molten salt outlet of the cold molten salt tank and the hot molten salt inlet of the hot molten salt tank, and is connected to the power grid, and is used to convert electrical energy into thermal energy, and use the thermal energy to heat the cold molten salt output from the cold molten salt tank. After the cold molten salt is heated, it becomes hot molten salt and is stored in the hot molten salt tank; The molten salt heat exchanger is arranged between the cold molten salt outlet of the cold molten salt tank and the hot molten salt inlet of the hot molten salt tank, and the steam inlet of the molten salt heat exchanger is connected to the steam outlet of the coal-fired boiler. The cold molten salt output from the cold molten salt tank and the steam sent from the coal-fired boiler exchange heat in the molten salt heat exchanger. The cold molten salt absorbs the heat of the steam and becomes hot molten salt and enters the hot molten salt tank. The steam loses heat and is discharged from the molten salt heat exchanger. The auxiliary generating device is used to provide desalted water. The auxiliary generating device includes a steam generator. The steam salt inlet of the steam generator is connected to the hot molten salt outlet of the hot molten salt tank, and the steam salt outlet of the steam generator is connected to the cold molten salt inlet of the cold molten salt tank. The steam generator is used to utilize the thermal energy of the hot molten salt output from the hot molten salt tank to heat the desalted water to generate auxiliary steam and supply it to the steam main of the coal-fired boiler. After the hot molten salt loses heat, it becomes cold molten salt and enters the cold molten salt tank.

[0007] Specifically, the heating system also includes: a molten salt preheater, having a salt inlet and a salt outlet, the salt inlet of the molten salt preheater is connected to the cold molten salt outlet of the cold molten salt tank, the salt outlet of the molten salt preheater is respectively connected to the heat exchange salt inlet of the molten salt heat exchanger and the heating salt inlet of the molten salt heater, and the molten salt preheater is used to preheat the cold molten salt sent from the cold molten salt tank.

[0008] Specifically, a first three-way valve is provided at the salt outlet of the molten salt preheater, and the salt outlet of the molten salt preheater is connected to the heat exchange salt inlet of the molten salt heat exchanger and the heating salt inlet of the molten salt heater through the first three-way valve.

[0009] Specifically, the heating system further includes: a low-temperature molten salt pump, which is arranged between the cold molten salt tank and the molten salt preheater and is used to pump the cold molten salt in the cold molten salt tank into the molten salt preheater.

[0010] Specifically, a high-temperature molten salt pump is provided at the molten salt outlet of the molten salt tank, for pumping the molten salt in the molten salt tank to the steam generator.

[0011] Specifically, the hot molten salt outlet of the hot molten salt tank is connected with the cold molten salt inlet of the cold molten salt tank and the steam salt inlet of the steam generator through a second three-way valve.

[0012] Specifically, the auxiliary generating device further comprises: a water storage tank for storing desalted water and supplying desalted water to the steam generator.

[0013] Specifically, a first regulating valve is provided on the connecting pipe between the steam inlet of the molten salt heat exchanger and the steam outlet of the coal-fired boiler, for adjusting the flow state of steam in the connecting pipe between the steam inlet of the molten salt heat exchanger and the steam outlet of the coal-fired boiler.

[0014] Another aspect of the present invention provides a heating method for a coal-fired boiler coupled with molten salt heat storage, which is implemented based on the heating system for a coal-fired boiler coupled with molten salt heat storage according to any one of the above claims, and the heating method comprises: Obtain the operating conditions of the coal chemical system, and select the corresponding heating method according to the operating conditions of the coal chemical system; If the coal chemical system is in the start-up operation condition or the accident operation condition, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main pipe of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the coal chemical system is in normal operating conditions, the corresponding heating mode is determined according to the grid load.

[0015] Specifically, if the coal chemical system is in normal operating conditions: If the load demand of the power grid is low, the steam generated by the coal-fired boiler is used for heating. At the same time, the excess steam generated by the coal-fired boiler is sent to the molten salt heat exchanger to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which is then stored in the hot molten salt tank. If the grid is in a period of high load demand or a period of low load, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the grid load demand is low and the grid has green electricity supply, the steam generated by the coal-fired boiler will be used for heating. At the same time, the heat energy converted from green electricity will be used to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which will then be stored in the hot molten salt tank.

[0016] The present invention provides a heating system for a coal-fired boiler coupled with molten salt heat storage, wherein the hot molten salt is stored in a hot molten salt tank, and the cold molten salt is stored in a cold molten salt tank. The steam generated by the combustion of the coal-fired boiler can be used to supply heat to the coal chemical system, and the excess steam generated by the combustion of the coal-fired boiler can be sent to the molten salt heat exchanger. The molten salt heat exchanger uses the heat of the steam to heat the cold molten salt sent from the cold molten salt tank, and the cold molten salt absorbs the heat of the steam to become hot molten salt and is stored in the hot molten salt tank; the electric energy provided by the power grid can also be converted into thermal energy through a molten salt heater, and the cold molten salt from the cold molten salt tank can be heated by the thermal energy to become hot molten salt and stored in the hot molten salt tank; when the hot molten salt needs to release heat, the hot molten salt in the hot molten salt tank enters the steam generator, and the heat released by the hot molten salt heats the desalted water entering the steam generator to generate auxiliary steam, and the auxiliary steam is sent to the steam main pipe of the coal-fired boiler, and the steam transported in the steam main pipe and the auxiliary steam are used to supply heat to the coal chemical system.

[0017] The heating system and heating method of the coal-fired boiler coupled with molten salt heat storage provided by the present invention enrich the heat source of the coal chemical system, and the hot molten salt releases heat to heat the desalted water, so that when the heating supply of the coal chemical system is insufficient, the heating supply of the coal chemical system can be quickly supplemented by auxiliary steam; the electric energy of the power grid is converted into thermal energy and then stored by hot molten salt, and the thermal energy of the excess steam is stored by hot molten salt, which improves the ability of the unit to participate in the peak load and peak load of the power grid, improves the safety and stability of the heating system, and solves the problem in the prior art that reliable steam heating cannot be provided in time when sudden accidents such as sudden fire extinguishing of the boiler or sudden tripping of chemical equipment occur in the coal chemical system.

[0018] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the layout of the heating system of the coal-fired boiler coupled with molten salt heat storage provided by the present invention.

[0020] Description of Reference Numerals 1-coal-fired boiler; 4-feedwater pump; 5-deaerator; 6-first regulating valve; 7-second regulating valve; 8-third regulating valve; 9-molten salt heater; 10-hot molten salt tank; 11-high-temperature molten salt pump; 12-second three-way valve; 13-steam generator; 14-cold molten salt tank; 15-low-temperature molten salt pump; 16-molten salt preheater; 17-first three-way valve; 18-molten salt heat exchanger; 19-water storage tank; 20-check valve. DETAILED DESCRIPTION

[0021] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0022] Figure 1 This is a schematic diagram of the layout of a heating system that combines a coal-fired boiler with molten salt heat storage. Figure 1 As shown, the present invention provides a heating system of a coal-fired boiler coupled with molten salt heat storage, which is used to supply heat to a coal chemical system. The heating system comprises: A hot molten salt tank 10, used for storing hot molten salt; A cold molten salt tank 14, used for storing cold molten salt; The molten salt heater 9 is connected between the cold molten salt outlet of the cold molten salt tank 14 and the hot molten salt inlet of the hot molten salt tank 10, and is connected to the power grid, and is used to convert electrical energy into thermal energy, and use the thermal energy to heat the cold molten salt output from the cold molten salt tank 14. After the cold molten salt is heated, it becomes hot molten salt and is stored in the hot molten salt tank 10; The molten salt heat exchanger 18 is arranged between the cold molten salt outlet of the cold molten salt tank 14 and the hot molten salt inlet of the hot molten salt tank 10, and the steam inlet of the molten salt heat exchanger 18 is connected to the steam outlet of the coal-fired boiler 1. The cold molten salt output from the cold molten salt tank 14 and the steam sent from the coal-fired boiler 1 exchange heat in the molten salt heat exchanger 18. After the cold molten salt absorbs the heat of the steam, it becomes hot molten salt and enters the hot molten salt tank 10. After the steam loses heat, it is discharged from the molten salt heat exchanger 18. The auxiliary generating device is used to provide desalted water. The auxiliary generating device includes a steam generator 13. The steam salt inlet of the steam generator 13 is connected to the hot molten salt outlet of the hot molten salt tank 10, and the steam salt outlet of the steam generator 13 is connected to the cold molten salt inlet of the cold molten salt tank 14. The steam generator 13 is used to utilize the thermal energy of the hot molten salt output by the hot molten salt tank 10 to heat the desalted water to generate auxiliary steam and supply it to the steam main pipe of the coal-fired boiler 1. After the hot molten salt loses heat, it becomes cold molten salt and enters the cold molten salt tank 14.

[0023] The present invention provides a heating system for a coal-fired boiler coupled with molten salt heat storage, such as Figure 1As shown, the hot molten salt tank 10 stores hot molten salt, and the cold molten salt tank 14 stores cold molten salt. The steam generated by the combustion of the coal-fired boiler 1 is sent to the steam main pipe to supply heat to the coal chemical system, and the excess steam generated by the combustion of the coal-fired boiler 1 is sent to the molten salt heat exchanger 18. The cold molten salt in the cold molten salt tank 14 enters the molten salt heat exchanger 18 to exchange heat with the steam. The cold molten salt absorbs the heat of the steam and becomes hot molten salt stored in the hot molten salt tank 10; the molten salt heater 9 converts the electric energy provided by the power grid into thermal energy, and uses the thermal energy to heat the cold molten salt sent from the cold molten salt tank 14 to the molten salt heater 9. The cold molten salt is heated to become hot molten salt and is stored in the hot molten salt tank 10. When the hot molten salt is needed, When hot, the molten salt stored in the molten salt tank 10 enters the steam generator 13, and the molten salt is used to release heat in the steam generator 13 to heat the desalted water entering the steam generator 13 to generate auxiliary steam, and the auxiliary steam is sent to the steam main pipe. The auxiliary steam and / or steam in the steam main pipe can be used to supply heat to the coal chemical system. The molten salt releases heat to heat the desalted water to generate auxiliary steam for heating, which improves the unit's ability to participate in the peak load and peak load of the power grid, and also improves the safety and stability of the heating system, and solves the problem in the prior art that reliable steam heating cannot be provided in time when sudden accidents such as sudden fire extinguishing of the boiler or sudden tripping of the chemical equipment occur in the coal chemical system.

[0024] In one embodiment, Figure 1 As shown, the heating system also includes: a molten salt preheater 16, having a salt inlet and a salt outlet, the salt inlet of the molten salt preheater 16 is connected to the cold molten salt outlet of the cold molten salt tank 14, the salt outlet of the molten salt preheater 16 is connected to the heat exchange salt inlet of the molten salt heat exchanger 18 and the heating salt inlet of the molten salt heater 9, respectively, and the molten salt preheater 16 is used to preheat the cold molten salt sent from the cold molten salt tank 14.

[0025] A first three-way valve 17 is provided at the salt outlet of the molten salt preheater 16 , and the salt outlet of the molten salt preheater 16 is connected to the heat exchange salt inlet of the molten salt heat exchanger 18 and the heating salt inlet of the molten salt heater 9 through the first three-way valve 17 .

[0026] The heating system further includes: a low-temperature molten salt pump 15 , which is disposed between the cold molten salt tank 14 and the molten salt preheater 16 and is used to pump the cold molten salt in the cold molten salt tank 14 into the molten salt preheater 16 .

[0027] A high-temperature molten salt pump 11 is provided at the molten salt outlet of the molten salt tank 10 for pumping the molten salt in the molten salt tank 10 to the steam generator 13 .

[0028] The hot molten salt outlet of the hot molten salt tank 10 is connected to the cold molten salt inlet of the cold molten salt tank 14 and the steam salt inlet of the steam generator 13 through a second three-way valve 12 .

[0029] The auxiliary generating device further comprises a water storage tank 19 for storing desalted water and supplying desalted water to the steam generator 13 .

[0030] A first regulating valve 6 is provided on the connecting pipe between the steam inlet of the molten salt heat exchanger 18 and the steam outlet of the coal-fired boiler 1 for adjusting the flow state of steam in the connecting pipe between the steam inlet of the molten salt heat exchanger 18 and the steam outlet of the coal-fired boiler 1 .

[0031] The cold molten salt stored in the cold molten salt tank 14 is pumped to the molten salt preheater 16 by a low-temperature molten salt pump 15 arranged between the cold molten salt tank 14 and the molten salt preheater 16. After the cold molten salt is preliminarily preheated by the molten salt preheater 16, the temperature of the cold molten salt increases, and the preheated cold molten salt can enter the molten salt heat exchanger 18 or the molten salt heater 9 through the first three-way valve 17. By adjusting the position of the valve core of the first three-way valve 17 in the valve cavity, the preheated cold molten salt can be controlled to enter the molten salt heat exchanger 18 or the molten salt heater 9. When the position of the valve core of the first three-way valve 17 in the valve cavity is adjusted so that the molten salt preheater 16 is connected to the molten salt heat exchanger 18 through the first three-way valve 17, the preheated cold molten salt enters the molten salt heat exchanger 18 to exchange heat with the steam entering the molten salt heat exchanger 18 at the same time. The preheated cold molten salt absorbs the waste heat of the steam and heats up again to become hot molten salt. After being discharged from the molten salt heat exchanger 18, it enters the hot molten salt tank 10 for storage. The temperature of the steam decreases after heat exchange with the preheated cold molten salt in the molten salt heat exchanger 18. In order to make full use of the waste heat of the steam, a deaerator 5 is provided. The steam inlet of the deaerator 5 is connected to the heat exchange steam outlet of the molten salt heat exchanger 18 by a pipeline, and the water outlet of the deaerator 5 is connected to the feed water of the coal-fired boiler 1 The water inlet is connected, the water inlet of the deaerator 5 is connected to the water outlet of the water storage tank 19 through a pipeline, a second regulating valve 7 is arranged on the pipeline between the water outlet of the water storage tank 19 and the water inlet of the deaerator 5, the flow state of the desalted water in the pipeline between the water outlet of the water storage tank 19 and the water inlet of the deaerator 5 is controlled by the second regulating valve 7, the cooled steam enters the deaerator 5 through the pipeline, the desalted water in the water storage tank 19 enters the deaerator 5 through the pipeline, the desalted water is heated by the cooled steam, the heated desalted water is sent to the coal-fired boiler 1 as boiler feed water, and a feed water pump 4 is also arranged between the deaerator 5 and the coal-fired boiler 1 to send feed water to the coal-fired boiler 1, so as to improve the thermal efficiency of the coal-fired unit. When the position of the valve core of the first three-way valve 17 in the valve cavity is adjusted so that the molten salt preheater 16 is connected to the molten salt heater 9 through the first three-way valve 17, the preheated cold molten salt enters the molten salt heater 9, the power grid provides electric energy to the molten salt heater 9, the molten salt heater 9 converts the electric energy into thermal energy to heat the preheated cold molten salt again to become hot molten salt, and the hot molten salt is discharged from the molten salt heater 9 and enters the hot molten salt tank 10 for storage.

[0032] The water outlet of the water storage tank 19 is connected to the steam inlet of the steam generator 13 through a pipeline, and a third regulating valve 8 is arranged on the pipeline between the water outlet of the water storage tank 19 and the steam inlet of the steam generator 13. When the hot molten salt needs to release heat, the hot molten salt outlet of the hot molten salt tank 10 is connected to the steam salt inlet of the steam generator 13 and the cold salt inlet of the cold molten salt tank 14 through the second three-way valve 12. By adjusting the position of the valve core in the valve cavity of the second three-way valve 12, the hot molten salt output from the hot molten salt tank 10 can be controlled to be sent to the steam generator 13 or the cold molten salt tank 14. The high-temperature molten salt pump 11 arranged at the hot molten salt outlet of the hot molten salt tank 10 pumps the hot molten salt in the hot molten salt tank 10 through the second three-way valve 12 and then enters the steam generator 13. At the same time, the desalted salt in the water storage tank 19 Water enters the steam generator 13, and the desalted water is heated by hot molten salt to generate auxiliary steam. The hot molten salt heats the desalted water and then cools down to become cold molten salt, which is discharged from the steam salt outlet of the steam generator 13 and enters the cold molten salt tank 14. The auxiliary steam is discharged from the steam generator 13 and enters the steam main pipe of the coal-fired boiler 1. In order to prevent the auxiliary steam discharged from the steam generator 13 from backflowing, a one-way valve 20 is provided at the steam outlet of the steam generator 13. The one-way valve 20 prevents the auxiliary steam from backflowing. After the auxiliary steam enters the steam main pipe, it supplies heat to the coal chemical system through the steam main pipe. The steam generated by the combustion of the coal-fired boiler 1 also enters the steam main pipe, and finally supplies heat to the coal chemical system through the steam main pipe. The auxiliary steam and steam jointly supply heat to the coal chemical system, thereby improving the stability of the heat supply to the coal chemical system. Excess steam generated by the combustion of the coal-fired boiler 1 enters the molten salt heat exchanger 18 through the connecting pipe between the steam inlet of the molten salt heat exchanger 18 and the steam outlet of the coal-fired boiler 1. The flow state of the steam in the connecting pipe between the steam inlet of the molten salt heat exchanger 18 and the steam outlet of the coal-fired boiler 1 is controlled by the first regulating valve 6. The first regulating valve 6 is opened, and the excess steam enters the molten salt heat exchanger 18 through the connecting pipe between the steam inlet of the molten salt heat exchanger 18 and the steam outlet of the coal-fired boiler 1. The steam exchanges heat with the preheated cold molten salt in the molten salt heat exchanger 18, and the preheated cold molten salt is heated by the steam heat to become hot molten salt. The cooled steam enters the deaerator 5.

[0033] Another aspect of the present invention provides a heating method for a coal-fired boiler coupled with molten salt heat storage, which is implemented based on the heating system for a coal-fired boiler coupled with molten salt heat storage according to any one of the above claims, and the heating method comprises: Obtain the operating conditions of the coal chemical system, and select the corresponding heating method according to the operating conditions of the coal chemical system; If the coal chemical system is in the start-up operation condition or the accident operation condition, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main pipe of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the coal chemical system is in normal operating conditions, the corresponding heating mode is determined according to the grid load.

[0034] When the coal chemical system is in normal operating conditions: If the load demand of the power grid is low, the steam generated by the coal-fired boiler is used for heating. At the same time, the excess steam generated by the coal-fired boiler is sent to the molten salt heat exchanger to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which is then stored in the hot molten salt tank. If the grid is in a period of high load demand or a period of low load, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the grid load demand is low and the grid has green electricity supply, the steam generated by the coal-fired boiler will be used for heating. At the same time, the heat energy converted from green electricity will be used to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which will then be stored in the hot molten salt tank.

[0035] When the coal chemical system is in operation, the first regulating valve 6 is opened, and the hot molten salt outlet of the hot molten salt tank 10 and the steam salt inlet of the steam generator 13 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17. At this time, the coal chemical system needs a large amount of steam for pipeline purging. Under this condition, the coal-fired boiler 1 is fully operated, and the high-temperature molten salt pump 11 pumps hot molten salt to the steam generator 13. The hot molten salt exchanges heat with the desalted water from the water storage tank 19 in the steam generator 13 to generate high-temperature and high-pressure auxiliary steam, which is sent to After the steam supply main, it enters the coal chemical system to supply pipeline purging. After the heat exchange, the hot molten salt loses heat and becomes cold molten salt. It is discharged from the steam salt outlet of the steam generator 13 and enters the cold molten salt tank 14. The cold molten salt in the cold molten salt tank 14 is pumped into the molten salt preheater 16 by the low-temperature molten salt pump 15, and then enters the molten salt heater 9 for further heating. The molten salt heater 9 converts the electric energy provided by the power grid into thermal energy and heats the preheated cold molten salt to become hot molten salt. This cycle process continuously generates auxiliary steam. At this time, the steam generated by the coal-fired boiler 1 and the auxiliary steam generated by heating the desalted water with the hot molten salt are jointly used for heating.

[0036] When the coal chemical system is in an accident operation state, a boiler is extinguished or an equipment of the coal chemical system has an accident and trips, the first regulating valve 6 is closed, and the hot molten salt outlet of the hot molten salt tank 10 and the steam salt inlet of the steam generator 13 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17. Since the amount of steam required by the coal chemical production chain is insufficient, at this time, while the coal-fired boiler 1 is operated to increase the load to provide steam heating, the hot molten salt releases heat to heat the desalted water to generate auxiliary steam for heating; according to the accident handling time, the power grid can be used to supply power to the molten salt heater 9 to use the heat energy converted from electrical energy to heat the cold molten salt into hot molten salt, and then the hot molten salt is sent to the steam generator 13 to release heat to heat the desalted water to generate auxiliary steam to make up for the steam gap, thereby providing a guarantee for the equipment to resume operation. In this case, after the cold molten salt is heated by the molten salt heater 9, the electrical energy is converted into thermal energy. The cold molten salt is heated by humans to become hot molten salt and is sent to the hot molten salt tank 10 for storage. The hot molten salt then enters the steam generator 13 to exchange heat with the desalted water to produce high-temperature and high-pressure auxiliary steam. The auxiliary steam is sent to the steam main pipe and is sent to the coal chemical system together with the steam delivered by the coal-fired boiler 1 for production. The cold molten salt discharged from the steam generator 13 enters the cold molten salt tank 14, is preheated by the molten salt preheater 16, and is sent to the molten salt heater 9 for continued heating to form a circulation process. At this time, the system is heated by the steam generated by the coal-fired boiler 1 and the auxiliary steam generated by the desalted water released by the hot molten salt.

[0037] When the coal chemical system is in normal operation, if it is in a period of low load demand of the power grid, the first control valve 6 is opened, and the hot molten salt outlet of the hot molten salt tank 10 and the cold molten salt inlet of the cold molten salt tank 14 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17, so as to maintain the load of the coal-fired boiler 1 in the economic load operation range, and the excess steam generated by the coal-fired boiler 1 is sent to the molten salt heat exchanger 18, and the heat of the steam is absorbed by the cold molten salt to become hot molten salt to temporarily store the heat of the steam, so as to meet the deep peak regulation requirements of the power grid, and the steam after heat exchange enters the deaerator 5 to heat the desalted water to be provided to the coal-fired boiler 1 as feed water, so as to improve the thermal efficiency of the unit. In this case, the cold molten salt is heated successively by the molten salt preheater 16 and the molten salt heat exchanger 18 to become hot molten salt and enter the hot molten salt tank 10 for storage, and then enters the cold molten salt tank 14 to form a circulation process, and at this time, the coal-fired boiler 1 is completely used to supply heat to the coal chemical system.

[0038] When the coal chemical system is in normal operation, if it is in a period of high grid load demand, the first control valve 6 is closed, the hot molten salt outlet of the hot molten salt tank 10 and the steam salt inlet of the steam generator 13 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17. The coal-fired boiler 1 is running at full load, and the hot molten salt releases heat to heat the desalted water to produce auxiliary steam. The steam and auxiliary steam are supplied to the coal chemical production system, thereby improving the grid peak capacity of the unit. In this case, the hot molten salt is discharged from the hot molten salt tank 10 and enters the steam generator 13 to heat the desalted water to produce high-temperature and high-pressure auxiliary steam. After the hot molten salt loses heat, it is discharged from the steam generator 13 and enters the cold molten salt tank 14. The cold molten salt enters the molten salt preheater 16 for preheating. The preheated cold molten salt enters the molten salt heater 9 to heat and form hot molten salt and store it in the hot molten salt tank 10. In this cycle, the coal chemical system is heated by the steam generated by the coal-fired boiler 1 and the auxiliary steam generated by the hot molten salt heating the desalted water.

[0039] When the coal chemical system is in normal operating conditions, if it is in the off-peak period of the power grid load, the hot molten salt outlet of the hot molten salt tank 10 and the steam salt inlet of the steam generator 13 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17, and the molten salt heater 9 is powered by the abandoned electricity of new energy or the off-peak electricity. The molten salt heater 9 heats the preheated cold molten salt into hot molten salt, and the hot molten salt releases heat to heat the desalted water to generate auxiliary steam for heating. The auxiliary steam replaces part of the heat load of the coal-fired boiler 1, thereby reducing the coal consumption of the coal-fired boiler 1 and improving the overall economy of the system. In this case, the preheated molten salt is heated by the molten salt heater 9 to become hot molten salt, and enters the hot molten salt tank 10. The hot molten salt is sent to the steam generator 13 through the high-temperature molten salt pump 11 to heat the desalted water to produce auxiliary steam. The hot molten salt after heat exchange loses heat and becomes cold molten salt and enters the cold molten salt tank 14. The cold molten salt is sent to the molten salt preheater 16 for preheating through the low-temperature molten salt pump 15. The preheated cold molten salt enters the molten salt heater 9, and the cycle continues. At this time, the coal chemical system is heated by the steam generated by the coal-fired boiler 1 and the auxiliary steam generated by heating the desalted water with the hot molten salt.

[0040] When the coal chemical system is in normal operating conditions, if the grid load demand is low and the grid has green electricity supply period, the first control valve 6 is opened, and the hot molten salt outlet of the hot molten salt tank 10 and the cold molten salt inlet of the cold molten salt tank 14 are connected through the second three-way valve 12, and the molten salt preheater 16 and the molten salt heater 9 are connected through the first three-way valve 17. The green electricity is used to supply power to the molten salt heater 9 to convert electrical energy into thermal energy and then heat the preheated cold molten salt to become hot molten salt, and the hot molten salt is stored in the hot molten salt tank 10 until the hot molten salt releases heat in the next period. In this case, the preheated cold molten salt is heated by the molten salt heater 9 and enters the hot molten salt tank 10. The hot molten salt is pumped into the cold molten salt tank 14 by the high-temperature molten salt pump 11, and then pumped into the molten salt preheater 16 for preheating by the low-temperature molten salt pump 15. The preheated cold molten salt enters the molten salt heater 9, and the cycle continues. At this time, the coal chemical system is heated solely by the coal-fired boiler 1, and the cold molten salt is used to absorb the thermal energy converted from green electricity, thereby storing heat.

[0041] The present invention provides a heating system for a coal-fired boiler coupled with molten salt heat storage, wherein the hot molten salt is stored in a hot molten salt tank, and the cold molten salt is stored in a cold molten salt tank. The steam generated by the combustion of the coal-fired boiler can be used to supply heat to the coal chemical system, and the excess steam generated by the combustion of the coal-fired boiler can be sent to the molten salt heat exchanger. The molten salt heat exchanger uses the heat of the steam to heat the cold molten salt sent from the cold molten salt tank, and the cold molten salt absorbs the heat of the steam to become hot molten salt and is stored in the hot molten salt tank. The electric energy provided by the power grid can also be converted into thermal energy through a molten salt heater, and the thermal energy is used to heat the cold molten salt from the cold molten salt tank to become hot molten salt and be stored in the hot molten salt tank. When the hot molten salt needs to release heat, the hot molten salt in the hot molten salt tank enters the steam generator, and the heat released by the hot molten salt heats the desalted water to generate auxiliary steam, which is then sent to the steam main pipe of the coal-fired boiler. The steam and auxiliary steam transported in the steam main pipe are used to supply heat to the coal chemical system.

[0042] The heating system and heating method of the coal-fired boiler coupled with molten salt heat storage provided by the present invention enrich the heat source of the coal chemical system, and the hot molten salt releases heat to heat the desalted water, so that when the heating supply of the coal chemical system is insufficient, the heating supply of the coal chemical system can be quickly supplemented by auxiliary steam; the electric energy of the power grid is converted into thermal energy and then stored by hot molten salt, and the thermal energy of the excess steam is stored by hot molten salt, which improves the ability of the unit to participate in the peak load and peak load of the power grid, improves the safety and stability of the heating system, and solves the problem in the prior art that reliable steam heating cannot be provided in time when sudden accidents such as sudden fire extinguishing of the boiler or sudden tripping of chemical equipment occur in the coal chemical system.

[0043] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0045] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A heating system of a coal-fired boiler coupled with molten salt heat storage, characterized in that: Used to supply heat to the coal chemical system, the heating system comprises: A hot molten salt tank (10), used for storing hot molten salt; A cold molten salt tank (14), used for storing cold molten salt; A molten salt heater (9) is connected between the cold molten salt outlet of the cold molten salt tank (14) and the hot molten salt inlet of the hot molten salt tank (10), and is connected to the power grid, and is used to convert electrical energy into thermal energy, and use the thermal energy to heat the cold molten salt output from the cold molten salt tank (14); after the cold molten salt is heated, it becomes hot molten salt and is stored in the hot molten salt tank (10); The molten salt heat exchanger (18) is arranged between the cold molten salt outlet of the cold molten salt tank (14) and the hot molten salt inlet of the hot molten salt tank (10), and the steam inlet of the molten salt heat exchanger (18) is connected to the steam outlet of the coal-fired boiler (1). The cold molten salt output from the cold molten salt tank (14) and the steam sent from the coal-fired boiler (1) exchange heat in the molten salt heat exchanger (18). After the cold molten salt absorbs the heat of the steam, it becomes hot molten salt and enters the hot molten salt tank (10). After the steam loses heat, it is discharged from the molten salt heat exchanger (18); An auxiliary generating device is used to provide desalted water. The auxiliary generating device comprises a steam generator (13). A steam salt inlet of the steam generator (13) is connected to a hot molten salt outlet of a hot molten salt tank (10). A steam salt outlet of the steam generator (13) is connected to a cold molten salt inlet of a cold molten salt tank (14). The steam generator (13) is used to utilize the heat energy of the hot molten salt output from the hot molten salt tank (10) to heat the desalted water to generate auxiliary steam and supply the auxiliary steam to the steam main of the coal-fired boiler (1). After the hot molten salt loses heat, it becomes cold molten salt and enters the cold molten salt tank (14).

2. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 1 is characterized in that: The heating system further comprises: a molten salt preheater (16) having a salt inlet and a salt outlet, the salt inlet of the molten salt preheater (16) being connected to the cold molten salt outlet of the cold molten salt tank (14), the salt outlet of the molten salt preheater (16) being connected to the heat exchange salt inlet of the molten salt heat exchanger (18) and the heating salt inlet of the molten salt heater (9), respectively, and the molten salt preheater (16) being used to preheat the cold molten salt sent from the cold molten salt tank (14).

3. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 2 is characterized in that: A first three-way valve (17) is provided at the salt outlet of the molten salt preheater (16), and the salt outlet of the molten salt preheater (16) is connected to the heat exchange salt inlet of the molten salt heat exchanger (18) and the heating salt inlet of the molten salt heater (9) via the first three-way valve (17).

4. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 3 is characterized in that: The heating system further comprises: a low-temperature molten salt pump (15), which is arranged between the cold molten salt tank (14) and the molten salt preheater (16) and is used to pump the cold molten salt in the cold molten salt tank (14) into the molten salt preheater (16).

5. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 1, characterized in that: A high-temperature molten salt pump (11) is provided at the molten salt outlet of the molten salt tank (10) for pumping the molten salt in the molten salt tank (10) to the steam generator (13).

6. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 1, characterized in that: The hot molten salt outlet of the hot molten salt tank (10) is connected to the cold molten salt inlet of the cold molten salt tank (14) and the steam salt inlet of the steam generator (13) via a second three-way valve (12).

7. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 6 is characterized in that: The auxiliary generating device further comprises: a water storage tank (19) for storing desalted water and providing desalted water to the steam generator (13).

8. The heating system of coal-fired boiler coupled with molten salt heat storage according to claim 1, characterized in that: A first regulating valve (6) is provided on the connecting pipe between the steam inlet of the molten salt heat exchanger (18) and the steam outlet of the coal-fired boiler (1), for regulating the flow state of steam in the connecting pipe between the steam inlet of the molten salt heat exchanger (18) and the steam outlet of the coal-fired boiler (1).

9. A method for heating a coal-fired boiler coupled with molten salt heat storage, which is implemented based on the heating system for heating a coal-fired boiler coupled with molten salt heat storage according to any one of claims 1 to 8, characterized in that: The heating method comprises: Obtain the operating conditions of the coal chemical system, and select the corresponding heating method according to the operating conditions of the coal chemical system; If the coal chemical system is in the start-up operation condition or the accident operation condition, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main pipe of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the coal chemical system is in normal operating conditions, the corresponding heating mode is determined according to the grid load.

10. The heating method of coal-fired boiler coupled with molten salt heat storage according to claim 9, characterized in that: When the coal chemical system is in normal operating conditions: If the load demand of the power grid is low, the steam generated by the coal-fired boiler is used for heating. At the same time, the excess steam generated by the coal-fired boiler is sent to the molten salt heat exchanger to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which is then stored in the hot molten salt tank. If the grid is in a period of high load demand or a period of low load, the hot molten salt stored in the hot molten salt tank is used to heat the desalted water to generate auxiliary steam, and the auxiliary steam is sent to the steam main of the coal-fired boiler, and the auxiliary steam is combined with the steam generated by the coal-fired boiler to provide heat; If the grid load demand is low and the grid has green electricity supply, the steam generated by the coal-fired boiler will be used for heating. At the same time, the heat energy converted from green electricity will be used to heat the cold molten salt output from the cold molten salt tank into hot molten salt, which will then be stored in the hot molten salt tank.

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