A steam supply system for a coal-fired power plant and an operation method thereof

Abstract

The present invention relates to the technical field of steam supply for coal-fired power plants, and in particular to a steam supply system for coal-fired power plants and an operation method thereof. The steam supply system for coal-fired power plants comprises a coal-fired boiler, a first heat exchange device, a second heat exchange device, a third heat exchange device, a first pump body and a second pump body; the second heat exchange device is provided with a phase-change heat storage material and a heat exchange tube with a heat transfer fluid inside, the first heat exchange device is provided with a second heat exchange cavity and the first heat exchange cavity connected to the flue of the coal-fired boiler; the first pump body, the second heat exchange cavity and the heat exchange tube are connected in series in sequence to form a heat transfer fluid heating subsystem; the third heat exchange device is provided with a third heat exchange cavity and a fourth heat exchange cavity connected to a high-pressure water supply pipe, the heat exchange tube, the second pump body and the third heat exchange cavity are connected in series in sequence to form a steam heating subsystem; the fourth heat exchange cavity is connected to an industrial steam supply terminal; when the coal-fired unit is in a low-load state, the steam heating subsystem can supply steam to the industrial steam supply terminal without increasing the load of the coal-fired unit.

Description

Technical Field

[0001] The present invention relates to the technical field of steam supply for coal-fired power plants, and in particular to a steam supply system for coal-fired power plants and an operating method thereof. Background Art

[0002] The country encourages existing coal-fired power generation units to replace heating, actively shuts down small boilers for heating and industrial steam supply, and carries out heating transformation of pure condensing units that meet the heating conditions.

[0003] With the development and improvement of my country's industrial economy, the demand for industrial steam supply is increasing. Industrial steam supply parameters mainly include temperature, pressure, and flow. Industrial users generally sign steam purchase agreements with power plants and have strict requirements on steam supply parameters. Steam supply parameters are generally not allowed to fluctuate and require long-term stable supply.

[0004] At present, coal-fired power plants generally provide steam to industrial users through "cold reheating" or "hot reheating". However, the maximum steam supply of "cold reheating" and "hot reheating" will be limited by the overtemperature of the boiler reheater and the axial thrust of the turbine; therefore, the extraction volume of cold reheating and hot reheating must be kept within a safe range. When the coal-fired unit is peak-shifted to low load operation, the pressure of cold reheating and hot reheating will decrease and cannot meet the industrial steam supply requirements. In order to ensure that the industrial steam supply parameters meet the requirements, the load of the coal-fired unit needs to be increased, resulting in the unit's deep peak-shifting amplitude being limited. Summary of the invention

[0005] The technical problem to be solved by the present invention is: when a coal-fired unit supplies industrial steam through "cold reheating" or "hot reheating", in order to ensure that the industrial steam supply parameters meet the requirements, it is necessary to increase the load of the coal-fired unit, resulting in the unit's deep peak regulation amplitude being limited.

[0006] Based on this, the present invention provides a steam supply system for a coal-fired power plant, comprising a coal-fired boiler, a first heat exchange device, a second heat exchange device, a third heat exchange device, a first pump body and a second pump body; the second heat exchange device is provided with a heat preservation cavity, the heat preservation cavity is provided with a phase change heat storage material and a heat exchange tube, and the heat exchange tube is provided with a heat transfer fluid;

[0007] The first heat exchange device is provided with a first heat exchange cavity and a second heat exchange cavity capable of conducting heat exchange, the first heat exchange cavity is connected to the flue of the coal-fired boiler, and the first pump body, the second heat exchange cavity and the heat exchange tube are connected in series in sequence to form a heat transfer liquid heating subsystem; the third heat exchange device is provided with a third heat exchange cavity and a fourth heat exchange cavity capable of conducting heat exchange, one end of the fourth heat exchange cavity is connected to the high-pressure water supply pipe, and the heat exchange tube, the second pump body and the third heat exchange cavity are connected in series in sequence to form a steam heating subsystem;

[0008] The other end of the fourth heat exchange chamber is connected to an industrial steam supply terminal, and the industrial steam supply terminal is also connected to a cold steam resupply system and / or a hot steam resupply system.

[0009] As a preferred solution, the steam supply system for the coal-fired power plant includes a fourth heat exchange device, the fourth heat exchange device is provided with a fifth heat exchange chamber and a sixth heat exchange chamber, the fifth heat exchange chamber is communicated with the rear end of the flue, the first heat exchange chamber is communicated with the front end of the flue, the first pump body, the sixth heat exchange chamber, the second heat exchange chamber and the heat exchange tube are sequentially connected in series to form the heat transfer liquid heating subsystem;

[0010] A first control valve is provided between the first heat exchange chamber and the flue, and a second control valve is provided between the fifth heat exchange chamber and the flue.

[0011] As a preferred solution, the insulation cavity is provided with a plurality of sub-insulation cavities arranged sequentially from top to bottom, each of the sub-insulation cavities is provided with a phase change heat storage material, and the phase change point of the phase change heat storage material in the upper sub-insulation cavity of two upper and lower adjacent sub-insulation cavities is higher than the phase change point of the phase change heat storage material in the lower sub-insulation cavity;

[0012] The heat exchange tube passes through each of the sub-insulation chambers in sequence from top to bottom, and the upper end of the heat exchange tube is connected to the liquid outlet end of the second heat exchange chamber.

[0013] As a preferred solution, the lower end of the heat exchange tube is connected to a first tube body and a second tube body, the other end of the first tube body is connected to the liquid inlet of the first pump body, and a third control valve is provided on the first tube body; the other end of the second tube body is connected to the liquid outlet of the third heat exchange cavity, and a fourth control valve is provided on the second tube body;

[0014] The upper end of the heat exchange tube is connected to the third tube body and the fourth tube body, the other end of the third tube body is connected to the liquid outlet end of the second heat exchange chamber, and the third tube body is provided with a fifth control valve; the other end of the fourth tube body is connected to the liquid inlet of the second pump body, and the fourth tube body is provided with a sixth control valve.

[0015] As a preferred solution, the steam supply system for a coal-fired power plant comprises a seventh pipe body and an eighth pipe body, the first end of the seventh pipe body is communicated with the third pipe body, and the first end of the seventh pipe body is located between the second heat exchange cavity and the fifth control valve; the second end of the seventh pipe body is communicated with the fourth pipe body, and the second end of the seventh pipe body is located between the sixth control valve and the second pump body, and the seventh pipe body is provided with a seventh control valve;

[0016] The first end of the eighth tube body is connected to the first tube body, and the first end of the eighth tube body is located between the first pump body and the third control valve; the second end of the eighth tube body is connected to the second tube body, and the second end of the eighth tube body is located between the fourth control valve and the third heat exchange device, and the eighth tube body is provided with an eighth control valve.

[0017] As a preferred solution, a first temperature sensor is provided on the first tube body, and a second temperature sensor is provided on the third tube body.

[0018] As a preferred embodiment, the third heat exchange device includes a preheater, an evaporator and a superheater, the superheater is provided with a first heating chamber and a first heating chamber, the evaporator is provided with a second heating chamber and a second heating chamber, the preheater is provided with a third heating chamber and a third heating chamber, the first heating chamber, the second heating chamber and the third heating chamber are connected in sequence to form the third heat exchange chamber, the first heating chamber, the second heating chamber and the third heating chamber are connected in sequence to form the fourth heat exchange chamber, the liquid outlet end of the second pump body is connected to the first heating chamber, and the third heating chamber is connected to the heat exchange tube; the third heating chamber is connected to the high-pressure water supply pipe, and the first heating chamber is connected to the industrial steam supply terminal.

[0019] An operating method of the steam supply system for a coal-fired power plant as described above comprises the following steps:

[0020] When the coal-fired unit is at medium or high load, shut down the steam heating subsystem, operate the thermal fluid heating subsystem, operate the cold re-steam supply system and / or the hot re-steam supply system;

[0021] When the coal-fired unit is under low load, the heat transfer fluid heating subsystem is turned off and the steam heating subsystem is turned on; the cold steam resupply system and the hot steam resupply system are turned off or on according to steam supply parameter requirements.

[0022] As a preferred solution, when the coal-fired unit is at low load: close the fifth control valve and the third control valve; run the first pump body and the second pump body; open the first control valve, the second control valve, the seventh control valve, the sixth control valve, the fourth control valve and the eighth control valve.

[0023] As a preferred solution, when the second heat exchange device fails: close the third control valve, the fourth control valve, the fifth control valve and the sixth control valve; open the first control valve, the second control valve, the seventh control valve and the eighth control valve; and close or open the cold resteam supply system and the hot resteam supply system according to the steam supply parameter requirements.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The steam supply system for a coal-fired power plant of the present invention comprises a second heat exchange device provided with a heat preservation chamber, in which a phase change heat storage material and a heat exchange tube are provided, and in which a heat transfer liquid is provided; the first heat exchange device comprises a first heat exchange chamber and a second heat exchange chamber capable of conducting heat exchange, the first heat exchange chamber is connected to the flue of the coal-fired boiler, the first pump body, the second heat exchange chamber and the heat exchange tube are connected in series in sequence to form a heat transfer liquid heating subsystem; the third heat exchange device comprises a third heat exchange chamber and a fourth heat exchange chamber capable of conducting heat exchange, one end of the fourth heat exchange chamber is connected to the high-pressure water supply pipe, the heat exchange tube, the second pump body and the third heat exchange chamber are connected in series in sequence to form a steam heating subsystem; the other end of the fourth heat exchange chamber is connected to the steam inlet side of the industrial steam supply terminal, and the steam inlet side of the industrial steam supply terminal is also connected to the It is connected to a cold steam resupply system and / or a hot steam resupply system; when the coal-fired unit is in a high-load state, the cold steam resupply system and / or the hot steam resupply system are used to supply steam to the industrial steam supply terminal, and at the same time, the heat transfer fluid heating subsystem is used to absorb the flue gas heat to heat the phase change heat storage material, and the phase change heat storage material stores heat; when the coal-fired unit is in a low-load state, the steam heating subsystem is operated to heat the high-pressure water using the heat stored in the phase change heat storage material, so that the steam heating subsystem supplies steam to the industrial steam supply terminal; therefore, when the coal-fired unit is in a low-load state, the steam heating subsystem can supply steam to the industrial steam supply terminal without increasing the load of the coal-fired unit, thereby avoiding the limitation of the deep peak regulation amplitude of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the operation of the steam supply system for a coal-fired power plant of the present invention when the coal-fired unit is in a high-load state;

[0027] Figure 2 It is a schematic diagram of the operation of the steam supply system for a coal-fired power plant of the present invention when the coal-fired unit is in a low-load state;

[0028] Figure 3 It is a schematic diagram of the operation of the steam supply system for a coal-fired power plant of the present invention when the coal-fired unit is in an extremely low load state;

[0029] Figure 4 This is a schematic diagram of the operation of the steam supply system for a coal-fired power plant of the present invention when a failure occurs in the second heat exchange device;

[0030] In the figure, 1, coal-fired boiler; 2, first heat exchange device; 3, second heat exchange device; 4, third heat exchange device; 41, superheater; 42, evaporator; 43, preheater; 5, first pump body; 6, second pump body; 7, high-pressure water supply pipe; 8, industrial steam supply terminal; 9, cold re-steam supply system; 10. Hot re-steam supply system; 11. Fourth heat exchange device; 13. First control valve; 14. Second control valve; 15. First pipe body; 16. Second pipe body; 17. Third control valve; 18. Fourth control valve; 19. Third pipe body; 20. Fourth pipe body; 21. Fifth control valve; 22. Sixth control valve; 23. Seventh pipe body; 24. Eighth pipe body; 25. Seventh control valve; 26. Eighth control valve; 27. Ninth control valve; 28. Tenth control valve; 29. ​​Denitration device; 30. Air preheater; 31. Ninth pipe body; 32. Tenth pipe body; 33. Eleventh pipe body; 34. Twelfth pipe body. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the "first" information may also be referred to as the "second" information, and similarly, the "second" information may also be referred to as the "first" information.

[0033] like Figures 1 to 4As shown, a preferred embodiment of a steam supply system for a coal-fired power plant of the present invention comprises a coal-fired boiler 1, a first heat exchange device 2, a second heat exchange device 3, a third heat exchange device 4, a first pump body 5 and a second pump body 6; the second heat exchange device 3 is provided with a heat preservation cavity, in which a phase change heat storage material and a heat exchange tube are provided, and a heat transfer fluid is provided in the heat exchange tube; the first heat exchange device 2 is provided with a first heat exchange cavity and a second heat exchange cavity capable of heat conduction, the first heat exchange cavity is connected to the flue of the coal-fired boiler 1, and the first pump body 5, the second heat exchange cavity and the heat exchange tube are connected in series in sequence to form a heat transfer fluid heating subsystem; the third heat exchange device 4 is provided with a third heat exchange cavity and a fourth heat exchange cavity capable of heat conduction, one end of the fourth heat exchange cavity is connected to the high-pressure water supply pipe 7, the heat exchange tube, the second pump body 6 The third heat exchange chamber is connected in series to form a steam heating subsystem; the other end of the fourth heat exchange chamber is connected to the steam inlet side of the industrial steam supply terminal 8, and the steam inlet side of the industrial steam supply terminal 8 is also connected to the cold steam resupply system 9 and / or the hot steam resupply system 10. When the coal-fired unit is in a high-load state, the cold steam resupply system and / or the hot steam resupply system are used to supply steam to the industrial steam supply terminal. At the same time, the heat transfer liquid heating subsystem is used to absorb the heat of the flue gas to heat the phase change heat storage material, and the phase change heat storage material stores heat; when the coal-fired unit is in a low-load state, the steam heating subsystem is operated, and the heat stored in the phase change heat storage material is used to heat the high-pressure water, so that the steam heating subsystem supplies steam to the industrial steam supply terminal 8; therefore, when the coal-fired unit is in a low-load state, the steam heating subsystem can supply steam to the industrial steam supply terminal without increasing the load of the coal-fired unit, thereby avoiding the limitation of the deep peak regulation amplitude of the unit. Moreover, by coupling the coal-fired boiler with the second heat exchanger, the steam heat source is increased, the industrial heating capacity is improved, and the efficient and stable supply of industrial heating is realized, avoiding the unsafe problems of the unit such as overheating of the coal-fired boiler reheater and unbalanced axial thrust of the steam turbine. The second heat exchanger is used to store a part of the heat of the boiler high-temperature flue gas at medium and high loads of the coal-fired unit, and it is used as the heat source for generating industrial steam supply when the coal-fired unit is low-loaded, which solves the problems of limited flow and insufficient pressure during cold re-steam supply and hot re-steam supply, improves the heat utilization efficiency, and reduces the system coal consumption rate.

[0034] In this embodiment, the steam supply system for coal-fired power plants includes a fourth heat exchange device 11, which is provided with a fifth heat exchange chamber and a sixth heat exchange chamber. The fifth heat exchange chamber is connected to the rear end of the flue, and the first heat exchange chamber is connected to the front end of the flue. The first pump body 5, the sixth heat exchange chamber, the second heat exchange chamber and the heat exchange tube are connected in series in sequence to form a heat transfer fluid heating subsystem. The temperature at the front end of the flue is higher than the temperature at the rear end of the flue. When the heat transfer fluid heating subsystem is in operation, the first pump body 5 first passes the heat transfer fluid with a lower heat exchange temperature into the sixth heat exchange chamber and then into the second heat exchange chamber, which can realize the cascade utilization of flue gas energy and improve the heating efficiency of flue gas to the heat transfer fluid.

[0035] Specifically, the water in the high-pressure water supply pipe is taken from the high-temperature condensate at the outlet of the low-pressure heater of the steam turbine or the high-temperature condensate in the deaerator, and the heat transfer fluid is heat transfer oil. A first control valve 13 is provided between the first heat exchange chamber and the flue, and a second control valve 14 is provided between the fifth heat exchange chamber and the flue. A denitrification device 29 and an air preheater 30 are sequentially arranged in the flue of the coal-fired boiler 1 from front to back; the air inlet end of the fifth heat exchange chamber is connected to a ninth tube body 31, and the end of the ninth tube body 31 away from the fifth heat exchange chamber is arranged between the denitrification device 29 and the air preheater 30, and the air outlet end of the fifth heat exchange chamber is connected to a tenth tube body 32, and the end of the tenth tube body 32 away from the fifth heat exchange chamber is arranged behind the smoke outlet of the air preheater 30; the air inlet end of the first heat exchange chamber is connected to an eleventh tube body 33, and the end of the eleventh tube body 33 away from the first heat exchange chamber is arranged in the flue in front of the denitrification device 29, and the air outlet end of the first heat exchange chamber is connected to a twelfth tube body 34, and the end of the twelfth tube body 34 away from the first heat exchange chamber is arranged between the end of the eleventh tube body 33 away from the first heat exchange chamber and the denitrification device 29.

[0036] In this embodiment, in order to realize the step-by-step heating of the phase change heat storage material by the heat transfer fluid, a plurality of sub-insulation chambers arranged in sequence from top to bottom are provided in the insulation chamber, each sub-insulation chamber is provided with a phase change heat storage material, and the phase change point of the phase change heat storage material in the upper sub-insulation chamber of two upper and lower adjacent sub-insulation chambers is higher than the phase change point of the phase change heat storage material in the lower sub-insulation chamber; the heat exchange tube passes through each sub-insulation chamber in sequence from top to bottom, and the upper end of the heat exchange tube is connected to the liquid outlet end of the second heat exchange chamber.

[0037] Among them, the lower end of the heat exchange tube is connected to the first tube body 15 and the second tube body 16, the other end of the first tube body 15 is connected to the liquid inlet of the first pump body 5, and the first tube body 15 is provided with a third control valve 17; the other end of the second tube body 16 is connected to the liquid outlet of the third heat exchange cavity, and the second tube body 16 is provided with a fourth control valve 18; the upper end of the heat exchange tube is connected to the third tube body 19 and the fourth tube body 20, the other end of the third tube body 19 is connected to the liquid outlet of the second heat exchange cavity, and the third tube body 19 is provided with a fifth control valve 21; the other end of the fourth tube body 20 is connected to the liquid inlet of the second pump body 6, and the fourth tube body 20 is provided with a sixth control valve 22.

[0038] Furthermore, the steam supply system for the coal-fired power plant includes a seventh tube body 23 and an eighth tube body 24, the first end of the seventh tube body 23 is connected to the third tube body 19, and the first end of the seventh tube body 23 is located between the second heat exchange chamber and the fifth control valve 21; the second end of the seventh tube body 23 is connected to the fourth tube body 20, and the second end of the seventh tube body 23 is located between the sixth control valve 22 and the second pump body 6, and the seventh tube body 23 is provided with a seventh control valve 25; the first end of the eighth tube body 24 is connected to the first tube body 15, and the first end of the eighth tube body 24 is located between the first pump body 5 and the third control valve 17; the second end of the eighth tube body 24 is connected to the second tube body 16, and the second end of the eighth tube body 24 is located between the fourth control valve 18 and the third heat exchange device 4, and the eighth tube body 24 is provided with an eighth control valve 26.

[0039] In this embodiment, in order to judge whether the phase change heat storage material has been heated to the optimal heat storage temperature, a first temperature sensor is provided on the first tube 15, and a second temperature sensor is provided on the third tube 19. When the difference between the temperature value measured by the second temperature sensor and the temperature value measured by the first temperature sensor is less than 5°C, the thermal fluid heating subsystem is stopped.

[0040] Furthermore, in order to realize the step-by-step heating of the high-pressure water by the heat transfer liquid, the third heat exchange device 4 includes a preheater 43, an evaporator 42 and a superheater 41. The superheater 41 is provided with a first heating chamber and a first heating chamber, the evaporator 42 is provided with a second heating chamber and a second heating chamber, the preheater 43 is provided with a third heating chamber and a third heating chamber, the first heating chamber, the second heating chamber and the third heating chamber are connected in sequence to form a third heat exchange chamber, the first heating chamber, the second heating chamber and the third heating chamber are connected in sequence to form a fourth heat exchange chamber, the liquid outlet end of the second pump body 6 is connected to the first heating chamber, and the third heating chamber is connected to the heat exchange pipe; the third heating chamber is connected to the high-pressure water supply pipe 7, and the first heating chamber is connected to the industrial steam supply terminal 8.

[0041] In this embodiment, in order to facilitate the control of the heat transfer liquid heating subsystem and the steam heating subsystem, a tenth control valve 28 is provided on the third tube body 19, and the tenth control valve 28 is arranged between the first end of the seventh tube body 23 and the second heat exchange chamber; a ninth control valve 27 is provided on the second tube body 16, and the ninth control valve 27 is arranged between the second end of the eighth tube body 24 and the preheater 43.

[0042] The embodiment of the operation method of the steam supply system for a coal-fired power plant described above comprises the following steps:

[0043] When the coal-fired unit is at medium or high load, Figure 1 As shown, shut down the steam heating subsystem, operate the thermal fluid heating subsystem, operate the cold resteam supply system and / or the hot resteam supply system;

[0044] When the coal-fired unit is at low load, Figure 2 As shown, the thermal fluid heating subsystem is turned off and the steam heating subsystem is turned on; the cold re-steam supply system and the hot re-steam supply system are turned off or on according to the steam supply parameter requirements.

[0045] Among them, when the load of the coal-fired unit is further reduced under low load, that is, when the coal-fired unit is at an extremely low load, such as Figure 3 As shown, the fifth control valve 21 and the third control valve 17 are closed; the first pump body 5 and the second pump body 6 are operated; the first control valve 13, the second control valve 14, the seventh control valve 25, the sixth control valve 22, the fourth control valve 18 and the eighth control valve 26 are opened. At this time, after the heat transfer fluid flows out of the preheater 43, a part of it flows into the heat exchange tube to absorb the heat stored in the phase change material, and the other part flows into the first heat exchange device 2 to absorb the heat carried by the flue gas of the coal-fired boiler 1; the above two parts of the heat transfer fluid enter the superheater 41 after absorbing the heat, and flow into the evaporator 42 and the preheater 43 in sequence, so as to heat the high-pressure water and ensure the stability of the steam supply when the coal-fired unit is at an extremely low load.

[0046] When the second heat exchange device 3 fails, Figure 4 As shown, the third control valve 17, the fourth control valve 18, the fifth control valve 21 and the sixth control valve 22 are closed; the first control valve 13, the second control valve 14, the seventh control valve 25 and the eighth control valve 26 are opened; the cold re-steam supply system and the hot re-steam supply system are closed or opened according to the steam supply parameter requirements. At this time, after the heat transfer fluid flows out of the preheater 43, it all flows into the first heat exchange device 2 to absorb the heat carried by the flue gas of the coal-fired boiler 1. At this time, the cold re-steam supply system or the hot re-steam supply system can be opened according to the steam supply requirements.

[0047] In summary, the steam supply system for coal-fired power plants of the present invention can not only realize the coupling between the coal-fired boiler and the second heat exchange device, but also use the high-temperature flue gas heat source as the heat source, and store the flue gas heat in the phase change energy storage material through the heat transfer fluid. Moreover, the coupling of the heat exchange device with the superheater, evaporator, and preheater can be utilized to absorb the heat stored in the phase change material through the heat transfer fluid, and heat to generate superheated steam for use by industrial users. When the second heat exchange device fails, the coal-fired boiler can be coupled with the superheater, evaporator, and preheater, and the heat transfer fluid absorbs the heat of the high-temperature flue gas, and directly heats to generate superheated steam for use by industrial users. When the coal-fired unit is at an extremely low load, the second heat exchange device is coupled with the superheater, evaporator, and preheater, while the coal-fired boiler is coupled with the superheater, evaporator, and preheater to achieve stable steam supply. In the above-mentioned coupling situations, the cold steam resupply system and the hot steam resupply system can be opened or closed according to the steam supply requirements, so that the steam supply system for coal-fired power plants of the present invention can maintain stable steam supply while achieving the goal of low energy consumption.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for operating a steam supply system for a coal-fired power plant, characterized in that: The steam supply system for a coal-fired power plant comprises a coal-fired boiler (1), a first heat exchange device (2), a second heat exchange device (3), a third heat exchange device (4), a first pump body (5) and a second pump body (6); the second heat exchange device (3) is provided with a heat preservation cavity, a phase change heat storage material and a heat exchange tube are provided in the heat preservation cavity, and a heat transfer fluid is provided in the heat exchange tube; The first heat exchange device (2) is provided with a first heat exchange chamber and a second heat exchange chamber capable of conducting heat exchange, the first heat exchange chamber is connected to the flue of the coal-fired boiler (1), and the first pump body (5), the second heat exchange chamber and the heat exchange tube are connected in series in sequence to form a heat transfer liquid heating subsystem; the third heat exchange device (4) is provided with a third heat exchange chamber and a fourth heat exchange chamber capable of conducting heat exchange, one end of the fourth heat exchange chamber is connected to the high-pressure water supply pipe (7), and the heat exchange tube, the second pump body (6) and the third heat exchange chamber are connected in series in sequence to form a steam heating subsystem; The other end of the fourth heat exchange chamber is connected to an industrial steam supply terminal (8), and the industrial steam supply terminal (8) is also connected to a cold re-steam supply system (9) and / or a hot re-steam supply system (10); The insulation cavity is provided with a plurality of sub-insulation cavities arranged sequentially from top to bottom, each of the sub-insulation cavities is provided with a phase change heat storage material, and the phase change point of the phase change heat storage material in the upper sub-insulation cavity of two upper and lower adjacent sub-insulation cavities is higher than the phase change point of the phase change heat storage material in the lower sub-insulation cavity; The heat exchange tube passes through each of the sub-insulation chambers in sequence from top to bottom, and the upper end of the heat exchange tube is connected to the liquid outlet end of the second heat exchange chamber; The lower end of the heat exchange tube is connected to a first tube body (15) and a second tube body (16); the other end of the first tube body (15) is connected to the liquid inlet of the first pump body (5), and a third control valve (17) is provided on the first tube body (15); the other end of the second tube body (16) is connected to the liquid outlet of the third heat exchange chamber, and a fourth control valve (18) is provided on the second tube body (16); The upper end of the heat exchange tube is connected to a third tube body (19) and a fourth tube body (20); the other end of the third tube body (19) is connected to the liquid outlet of the second heat exchange chamber, and the third tube body (19) is provided with a fifth control valve (21); the other end of the fourth tube body (20) is connected to the liquid inlet of the second pump body (6), and the fourth tube body (20) is provided with a sixth control valve (22); The steam supply system for a coal-fired power plant comprises a seventh pipe body (23) and an eighth pipe body (24); the first end of the seventh pipe body (23) is in communication with the third pipe body (19), and the first end of the seventh pipe body (23) is located between the second heat exchange cavity and the fifth control valve (21); the second end of the seventh pipe body (23) is in communication with the fourth pipe body (20), and the second end of the seventh pipe body (23) is located between the sixth control valve (22) and the second pump body (6); and the seventh pipe body (23) is provided with a seventh control valve (25); The first end of the eighth tube (24) is in communication with the first tube (15), and the first end of the eighth tube (24) is located between the first pump (5) and the third control valve (17); the second end of the eighth tube (24) is in communication with the second tube (16), and the second end of the eighth tube (24) is located between the fourth control valve (18) and the third heat exchange device (4); the eighth tube (24) is provided with an eighth control valve (26); The first tube (15) is provided with a first temperature sensor, and the third tube (19) is provided with a second temperature sensor; The operation method of the steam supply system for a coal-fired power plant comprises the following steps: When the coal-fired unit is at medium or high load, shut down the steam heating subsystem, operate the thermal fluid heating subsystem, operate the cold re-steam supply system and / or the hot re-steam supply system; When the coal-fired unit is at low load, the heat transfer fluid heating subsystem is turned off and the steam heating subsystem is turned on; the cold steam resupply system and the hot steam resupply system are turned off or on according to the steam supply parameter requirements.

2. The method for operating a steam supply system for a coal-fired power plant according to claim 1, characterized in that: The steam supply system for a coal-fired power plant comprises a fourth heat exchange device (11), wherein the fourth heat exchange device (11) is provided with a fifth heat exchange chamber and a sixth heat exchange chamber, wherein the fifth heat exchange chamber is connected to the rear end of the flue; the first heat exchange chamber is connected to the front end of the flue, and the first pump body (5), the sixth heat exchange chamber, the second heat exchange chamber and the heat exchange tube are connected in series in sequence to form the heat transfer fluid heating subsystem; A first control valve (13) is provided between the first heat exchange chamber and the flue, and a second control valve (14) is provided between the fifth heat exchange chamber and the flue.

3. The method for operating a steam supply system for a coal-fired power plant according to claim 1, characterized in that: The third heat exchange device (4) comprises a preheater (43), an evaporator (42) and a superheater (41); the superheater (41) is provided with a first heating chamber and a first heat receiving chamber; the evaporator (42) is provided with a second heating chamber and a second heat receiving chamber; the preheater (43) is provided with a third heating chamber and a third heat receiving chamber; the first heating chamber, the second heating chamber and the third heating chamber are connected in sequence to form the third heat exchange chamber; the first heat receiving chamber, the second heat receiving chamber and the third heat receiving chamber are connected in sequence to form the fourth heat exchange chamber; the liquid outlet end of the second pump body (6) is connected to the first heating chamber, and the third heating chamber is connected to the heat exchange pipe; the third heat receiving chamber is connected to the high-pressure water supply pipe (7), and the first heat receiving chamber is connected to the industrial steam supply terminal (8).

4. The method for operating a steam supply system for a coal-fired power plant according to claim 1, characterized in that: When the coal-fired unit is at low load: the fifth control valve (21) and the third control valve (17) are closed; the first pump body (5) and the second pump body (6) are operated; and the first control valve (13), the second control valve (14), the seventh control valve (25), the sixth control valve (22), the fourth control valve (18) and the eighth control valve (26) are opened.

5. The method for operating a steam supply system for a coal-fired power plant according to claim 1, characterized in that: When a failure occurs in the second heat exchange device (3): the third control valve (17), the fourth control valve (18), the fifth control valve (21) and the sixth control valve (22) are closed; the first control valve (13), the second control valve (14), the seventh control valve (25) and the eighth control valve (26) are opened; and the cold re-steam supply system and the hot re-steam supply system are closed or opened according to steam supply parameter requirements.

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