A coal-fired unit rapid start-up system and method based on working fluid heat storage

Abstract

The present invention discloses a rapid start-up system and method for a coal-fired unit based on working fluid heat storage, and relates to the technical field of rapid start-up of coal-fired units. The system mainly includes a boiler, a feed water pump, a deaerator, a condenser, a condensate pump and a heat storage system. Before the coal-fired unit is started, the high-temperature hot water from the outlet of the adjacent machine pre-pump is stored in the heat storage system; when the coal-fired unit is started, the high-temperature water stored in the heat storage system is pressurized by the hot water discharge pump and sent to the condensate pipe at the inlet of the deaerator, and finally enters the boiler through the feed water pump, thereby playing the role of heating the furnace. During the entire startup process, the auxiliary steam consumption, oil consumption, coal consumption and startup power consumption are all reduced, and the startup time is also reduced, which solves the problem of the long conventional startup time of the boiler of the coal-fired unit.

Description

Technical Field

[0001] The present invention relates to the technical field of rapid start-up of coal-fired units, and in particular to a rapid start-up system and method of coal-fired units based on working fluid heat storage. Background Art

[0002] At present, the conventional startup process of the boiler of a coal-fired unit is as follows: before the boiler is started, the deaerator is heated by auxiliary steam to start warming up the boiler. At this time, the temperature of the boiler water-cooled wall is generally the ambient temperature. Since the heating rate of the auxiliary steam is slow, the temperature rise rate of the boiler water-cooled wall is low (0.1 ℃ / min); when the temperature of the boiler water-cooled wall rises to 40 ℃, the boiler starts to start, the boiler is ignited and oil is added, and the temperature rise rate of the boiler water-cooled wall is generally 0.4 ℃ / min; when the temperature of the boiler water-cooled wall is 70 ℃, the coal feeder feeds coal, and the temperature rise rate of the boiler water-cooled wall is 1.5 ℃ / min; when the boiler water-cooled wall is heated to 170 ℃, the feed water temperature is about 100 ℃, and the startup time is about 5 hours, after which the temperature rise rate of the boiler water-cooled wall is 0.75 ℃ / min; when the boiler water-cooled wall is heated to 260 ℃, the feed water temperature is 145~150 ℃, and the startup time is about 7 hours. The entire startup process is relatively long, resulting in the consumption of a lot of auxiliary steam, fuel oil, coal and electricity. Summary of the invention

[0003] The present invention provides a coal-fired unit rapid start-up system and method based on working fluid heat storage, which solves the technical problem that the conventional start-up process of the boiler of the coal-fired unit is long, resulting in the consumption of a lot of auxiliary steam, fuel oil, coal and electricity.

[0004] A first aspect of the present invention provides a coal-fired unit rapid start-up system based on working fluid heat storage, comprising a boiler, a feed water pump, a deaerator, a condenser, a condensate pump and a heat storage system;

[0005] The boiler is connected to the deaerator through the feed water pump, and the boiler drain pipe is connected to the deaerator and the condenser through a third valve and a fourth valve respectively;

[0006] The condenser outlet is connected to the condensate pump, and the heat storage system is respectively connected to the deaerator inlet pipe and the condensate pump outlet pipe.

[0007] Optionally, the heat storage system comprises a thermocline heat storage tank and a heat discharge pump;

[0008] The upper part of the thermocline heat storage tank is connected to the outlet of the pre-pump of the adjacent machine through the first valve, and the upper part of the thermocline heat storage tank is also connected to the inlet pipeline of the deaerator through the hot water pump and the first regulating valve;

[0009] The lower part of the thermocline layer heat storage tank is connected to the condenser of the adjacent machine through a second valve, and the lower part of the thermocline layer heat storage tank is also connected to the condensate pump outlet pipeline through a second regulating valve.

[0010] Optionally, the heat storage system includes a high-temperature heat storage tank, a low-temperature heat storage tank and a heat discharge pump;

[0011] The high-temperature heat storage tank is connected to the outlet of the pre-pump of the adjacent machine through the first valve, and the high-temperature heat storage tank is also connected to the inlet pipeline of the deaerator through the hot water pump and the first regulating valve;

[0012] The low-temperature heat storage tank is connected to the condenser of the adjacent machine through a second valve, and the low-temperature heat storage tank is also connected to the condensate pump outlet pipeline through a second regulating valve.

[0013] Optionally, when the heat storage system adopts a thermocline heat storage tank, the heat storage process includes:

[0014] Before the coal-fired unit is started, the high-temperature hot water at the outlet of the adjacent unit's front pump enters from the upper part of the thermocline layer heat storage tank and is stored in the thermocline layer heat storage tank; the cold water is discharged from the lower part of the thermocline layer heat storage tank and returned to the condenser of the adjacent unit; finally, the thermocline layer heat storage tank is filled with hot water;

[0015] The thermocline heat storage tank is a low-pressure pressure vessel with a working pressure of 0.8 MPa to 1.5 MPa; low-temperature water and high-temperature water are respectively located at the lower and upper parts of the thermocline heat storage tank, forming a thermocline layer in the middle.

[0016] Optionally, when the heat storage system adopts a thermocline heat storage tank, the heat release process includes:

[0017] When the coal-fired unit is started, the high-temperature water stored in the upper part of the thermocline heat storage tank is pressurized by the heat discharge pump and sent to the condensate pipe at the inlet of the deaerator, mixed with the main condensate and then enters the deaerator, and the hot water at the outlet of the deaerator enters the boiler through the feed water pump to warm the boiler; part of the drain water after heating returns to the deaerator, and part of the drain water returns to the condenser, and part of the condensate is sent from the condenser to the lower part of the thermocline heat storage tank through the condensate pump to maintain the working medium balance; the outlet water pressure of the condensate pump is higher than the working pressure of the thermocline heat storage tank.

[0018] Optionally, when the heat storage system uses a high-temperature heat storage tank and a low-temperature heat storage tank, the heat storage process includes:

[0019] The high-temperature hot water from the outlet of the adjacent machine's front pump is stored in the high-temperature heat storage tank, and cold water is discharged from the low-temperature heat storage tank to the condenser of the adjacent machine; before the coal-fired unit is started, the high-temperature heat storage tank is filled with auxiliary steam from the adjacent machine, and the steam is slowly discharged during the heat storage process, and the low-temperature heat storage tank is filled with cold water;

[0020] The high-temperature heat storage tank is a low-pressure pressure vessel, and its working pressure is 0.8MPa~1.5MPa. The low-temperature heat storage tank is a normal pressure container, and the volume of the low-temperature heat storage tank is the same as that of the high-temperature heat storage tank; high-temperature water and low-temperature water are stored in the high-temperature heat storage tank and the low-temperature heat storage tank respectively.

[0021] Optionally, when the heat storage system uses a high-temperature heat storage tank and a low-temperature heat storage tank, the heat release process includes:

[0022] When the coal-fired unit is started, the high-temperature water stored in the high-temperature heat storage tank is pressurized by the heat discharge pump and sent to the condensate pipe at the deaerator inlet, and enters the deaerator after being mixed with the main condensate; the hot water at the deaerator outlet enters the boiler through the feed water pump to warm the boiler; part of the drain water after heating returns to the deaerator, and part of the drain water returns to the condenser; part of the condensate is sent from the condenser to the low-temperature heat storage tank by the condensate pump to maintain the working medium balance.

[0023] The second aspect of the present invention provides a control method for a coal-fired unit rapid start-up system based on working fluid heat storage, and the control method before the boiler is ignited includes:

[0024] When the unit is started, the first valve and the second valve are closed, and the third valve, the fourth valve, the first regulating valve and the second regulating valve are opened, and the high-temperature water stored in the heat storage system is pressurized and sent to the condensate water pipeline at the inlet of the deaerator through the hot water discharge pump, and then mixed with the main condensate and enters the deaerator; the hot water at the outlet of the deaerator is sent to the boiler heater through the feed water pump;

[0025] By controlling the opening of the first regulating valve, the temperature of the hot water at the outlet of the deaerator is controlled, and then the temperature rise rate of the boiler water-cooled wall is controlled, so that the temperature rise rate of the boiler water-cooled wall is within a preset temperature rise range.

[0026] Optionally, after the boiler is ignited, the control method further includes:

[0027] When the outlet water temperature of the feed water pump rises to 100°C to heat the boiler water-cooled wall at 95°C, the coal feeder starts to feed coal, the deaerator starts auxiliary steam heating, and the opening of the first regulating valve is controlled so that the average temperature rise rate of the boiler water-cooled wall is 1.0°C / min; during this process, the condensate pump is turned on, and the opening of the second regulating valve is controlled to ensure that the water inlet and outlet of the heat storage system are consistent;

[0028] When the outlet water temperature of the feed water pump rises to 145-150° C., the first regulating valve and the second regulating valve are closed, and the boiler is completely heated by fuel combustion.

[0029] It can be seen from the above technical solutions that the present invention has the following advantages:

[0030] In the present invention, the boiler is connected to the deaerator through a feedwater pump, the boiler drain pipe is connected to the deaerator and the condenser through a third valve and a fourth valve respectively; the condenser outlet is connected to a condensate pump, and the heat storage system is connected to the deaerator inlet pipe and the condensate pump outlet pipe respectively. The conventional startup process of the boiler of the coal-fired unit is overcome, resulting in the technical problem of consuming a lot of auxiliary steam, fuel oil, coal and electricity, thereby reducing the boiler startup cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 A schematic diagram of a rapid start-up system for a coal-fired unit based on working fluid heat storage provided in Example 1 of the present invention Figure 1 ;

[0033] Figure 2 A schematic diagram of a rapid start-up system for a coal-fired unit based on working fluid heat storage provided in the second embodiment of the present invention Figure 2 ;

[0034] The reference numerals are as follows:

[0035] 1. Boiler; 2. Feed water pump; 3. Deaerator; 4. Condenser; 5. Condensate pump; 6. Inclined temperature layer heat storage tank; 7. Heat discharge pump; 8. Low-temperature heat storage tank; 9. High-temperature heat storage tank. DETAILED DESCRIPTION

[0036] The embodiment of the present invention provides a system and method for rapid startup of a coal-fired unit based on working fluid heat storage, which is used to solve the technical problem that the conventional startup process of the boiler of the coal-fired unit is long, resulting in the consumption of a lot of auxiliary steam, fuel oil, coal and electricity.

[0037] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Embodiment 1:

[0039] See also Figure 1-2 As shown, the present invention provides a coal-fired unit rapid start-up system based on working fluid heat storage, comprising a boiler 1, a feed water pump 2, a deaerator 3, a condenser 4, a condensate pump 5 and a heat storage system; the boiler 1 is connected to the deaerator 3 through the feed water pump 2, and the boiler 1 drain pipe is respectively connected to the deaerator 3 and the condenser 4 through the third valve V3 and the fourth valve V4; the outlet of the condenser 4 is connected to the condensate pump 5, and the heat storage system is respectively connected to the inlet pipe of the deaerator 3 and the outlet pipe of the condensate pump 5.

[0040] See also Figure 1 As shown, the heat storage system includes a thermocline heat storage tank 6 and a heat discharge water pump 7; the upper portion of the thermocline heat storage tank 6 is connected to the outlet of the pre-pump of the adjacent machine through the first valve V1, and the upper portion of the thermocline heat storage tank 6 is also connected to the inlet pipeline of the deaerator 3 through the heat discharge water pump 7 and the first regulating valve FV1; the lower portion of the thermocline heat storage tank 6 is connected to the condenser of the adjacent machine through the second valve V2, and the lower portion of the thermocline heat storage tank 6 is also connected to the outlet pipeline of the condensate pump 5 through the second regulating valve FV2.

[0041] In one embodiment, when the heat storage system is composed of a thermocline heat storage tank 6 and a heat discharge pump 7, before the coal-fired unit is started, the thermocline heat storage tank 6 is filled with cold water, and the high-temperature hot water from the outlet of the front pump of the adjacent coal-fired unit is stored in the upper part of the thermocline heat storage tank 6, and the cold water discharged from the lower part of the thermocline heat storage tank 6 is returned to the condenser of the adjacent coal-fired unit to ensure the normal progress of the heat storage process and maintain the working medium balance. When the coal-fired unit is started, the high-temperature water stored in the upper part of the thermocline heat storage tank 6 is pressurized and transported to the condensate pipe at the inlet of the deaerator 3 by the heat discharge pump 7, and enters the deaerator 3 after mixing with the main condensate; the hot water at the outlet of the deaerator 3 is transported to the boiler 1 by the feed water pump 2 to warm the boiler 1, and a part of the drain water after heating returns to the deaerator 3, and most of the drain water returns to the condenser 4. Part of the condensate is transported from the condenser 4 to the lower part of the thermocline layer heat storage tank 6 through the condensate pump 5, thereby preventing the hot well of the condenser 4 from overflowing and maintaining the working medium balance.

[0042] See also Figure 2As shown, the heat storage system includes a high-temperature heat storage tank 9, a low-temperature heat storage tank 8 and a heat discharge water pump 7; the high-temperature heat storage tank 9 is connected to the outlet of the pre-pump of the adjacent machine through the first valve V1, and the high-temperature heat storage tank 9 is also connected to the inlet pipeline of the deaerator 3 through the heat discharge water pump 7 and the first regulating valve FV1; the low-temperature heat storage tank 8 is connected to the condenser of the adjacent machine through the second valve V2, and the low-temperature heat storage tank 8 is also connected to the outlet pipeline of the condensate pump 5 through the second regulating valve FV2.

[0043] It is worth mentioning that when the heat storage system consists of a high-temperature heat storage tank 9, a low-temperature heat storage tank 8 and a heat discharge pump 7, before the coal-fired unit is started, the high-temperature heat storage tank 9 is filled with auxiliary steam from the adjacent coal-fired unit, and the steam is slowly discharged during the heat storage process to stabilize the pressure. The low-temperature heat storage tank 8 is filled with cold water, and the high-temperature hot water at the outlet of the adjacent coal-fired unit front pump is stored in the high-temperature heat storage tank 9. The cold water is discharged from the low-temperature heat storage tank 8 to the condenser of the adjacent coal-fired unit to maintain the working medium balance. When the coal-fired unit is started, the high-temperature water in the high-temperature heat storage tank 9 is pressurized and transported to the condensate pipe at the inlet of the deaerator 3 by the heat discharge pump 7, and enters the deaerator 3 after mixing with the main condensate. The hot water at the outlet of the deaerator 3 is transported to the boiler 1 through the feed water pump 2 to warm the boiler 1. A part of the drain water after heating returns to the deaerator 3, and most of the drain water returns to the condenser 4. Part of the condensate is delivered to the low-temperature heat storage tank 8 by the condensate pump 5, thereby preventing the hot well of the condenser 4 from overflowing and maintaining the working medium balance.

[0044] It should be noted that when the heat storage system adopts the inclined temperature layer heat storage tank 6, the heat storage process is as follows: before the coal-fired unit is started, the inclined temperature layer heat storage tank 6 is filled with cold water, and the high-temperature hot water from the outlet of the adjacent machine front pump enters from the upper part of the inclined temperature layer heat storage tank 6 and is stored in the inclined temperature layer heat storage tank 6. The cold water is discharged from the lower part of the inclined temperature layer heat storage tank 6 and returned to the condenser of the adjacent machine to maintain the working medium balance; the inclined temperature layer heat storage tank 6 is a low-pressure pressure vessel, and its working pressure is 0.8MPa~1.5MPa; the low-temperature water and the high-temperature water are respectively located at the lower and upper parts of the inclined temperature layer heat storage tank 6, forming an inclined temperature layer in the middle; the thinner the inclined temperature layer, the smaller the heat loss, and after the heat storage is completed, the inclined temperature layer will become thicker and thicker with the passage of time, so the heat storage process is generally carried out one day before the start-up.

[0045] It should be noted that when the heat storage system adopts the thermocline heat storage tank 6, the heat release process is as follows: when the coal-fired unit is started, the high-temperature water stored in the upper part of the thermocline heat storage tank 6 is pressurized by the heat release water pump 7 and sent to the condensate pipe at the inlet of the deaerator 3, and enters the deaerator 3 after mixing with the main condensate; the hot water at the outlet of the deaerator enters the boiler 1 through the feed water pump 2 to warm the boiler 1; part of the drain water after heating returns to the deaerator 3, and the other part of the drain water returns to the condenser 4. In order to prevent the hot well of the condenser 4 from overflowing, part of the condensate is sent to the lower part of the thermocline heat storage tank 6 through the condensate pump 5 to maintain the working medium balance; the outlet water pressure of the condensate pump 5 should be higher than the working pressure of the thermocline heat storage tank 6 to ensure the normal start-up process.

[0046] It should be noted that when the heat storage system adopts a high-temperature heat storage tank 9 and a low-temperature heat storage tank 8, the heat storage process is as follows: before the coal-fired unit is started, the high-temperature heat storage tank 9 is filled with auxiliary steam from the adjacent unit, and the pressure is maintained at the working pressure, and the low-temperature heat storage tank 8 is filled with cold water. The high-temperature hot water from the outlet of the adjacent unit's pre-pump is stored in the high-temperature heat storage tank 9, and the cold water is discharged from the low-temperature heat storage tank 8 to the condenser of the adjacent unit to maintain the working medium balance; the high-temperature heat storage tank 9 is a low-pressure pressure vessel with a working pressure of 0.8MPa~1.5MPa, and the low-temperature heat storage tank 8 is a normal pressure vessel. The volume of the high-temperature heat storage tank 9 is the same as that of the low-temperature heat storage tank 8, and its advantage is that the pressure vessel has a small volume and a low cost; high-temperature water and low-temperature water are stored in the high-temperature heat storage tank 9 and the low-temperature heat storage tank 8 respectively, without contacting each other, and the insulation effect is better; therefore, the heat storage process is more flexible and can be carried out in the early stage of startup without special time requirements.

[0047] It should be noted that during the startup of boiler 1, there is no need to add oil to boiler 1, and the use of auxiliary steam, coal consumption and electricity consumption are all reduced, thereby reducing the startup cost of boiler 1, and the startup time is shorter than the conventional startup, solving the problem of long conventional startup time of boiler 1 of the coal-fired unit.

[0048] It should be noted that, in the whole process, in order to prevent the hot well of the condenser 4 from overflowing, the condensate pump 5 is turned on, and the opening of the second regulating valve FV2 is controlled to ensure that the water inlet and outlet of the inclined temperature layer heat storage tank 6 (or the water outlet of the high temperature heat storage tank 9 and the water inlet of the low temperature heat storage tank 8) are consistent, so as to maintain the working medium balance.

[0049] In the embodiment of the present invention, the boiler drain pipe of the present invention is connected to the deaerator and the condenser through the third valve and the fourth valve respectively; the condenser outlet is connected to the condensate pump, and the heat storage system is connected to the deaerator inlet pipe and the condensate pump outlet pipe respectively. The conventional startup process of the boiler of the coal-fired unit is overcome, resulting in the technical problem of consuming a lot of auxiliary steam, fuel oil, coal and electricity, thereby reducing the boiler startup cost.

[0050] Embodiment 2:

[0051] The present invention provides a control method for a coal-fired unit rapid start-up system based on working fluid heat storage, and the boiler pre-ignition control method includes:

[0052] When the unit is started, the first valve V1 and the second valve V2 are closed first, and the third valve V3, the fourth valve V4, the first regulating valve FV1 and the second regulating valve FV2 are opened. The high-temperature water stored in the heat storage system is pressurized and sent to the condensate pipe at the deaerator inlet through the heat discharge pump, and then mixed with the main condensate to enter the deaerator; the hot water at the deaerator outlet is sent to the boiler heater through the feed water pump; the hot water temperature at the deaerator outlet is controlled by controlling the opening of the first regulating valve, and then the temperature rise rate of the boiler water-cooled wall is controlled to ensure that the temperature rise rate of the boiler water-cooled wall is within the preset temperature rise range (generally 1.3~1.5 ℃ / min). During this process, the boiler does not need to be added with oil, and the deaerator does not need auxiliary steam heating; when the outlet water temperature of the feed water pump rises to 100 ℃ to heat the boiler water-cooled wall temperature of 95 ℃, the coal feeder starts to feed coal, the deaerator starts auxiliary steam heating, and the opening of the first regulating valve is controlled to make the average temperature rise rate of the boiler water-cooled wall 1.0 ℃ / min; in this process, in order to prevent the condenser hot well from overflowing, the condensate pump is turned on, and the opening of the second regulating valve is controlled to ensure that the water inlet and outlet of the heat storage system are consistent to maintain the working medium balance; when the outlet water temperature of the feed water pump rises to 145~150 ℃, the first regulating valve and the second regulating valve are closed, and the boiler is completely heated by fuel combustion.

[0053] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0054] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0055] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coal-fired unit rapid start-up system based on working fluid heat storage, characterized in that: Includes boiler, feed water pump, deaerator, condenser, condensate pump and heat storage system; The boiler is connected to the deaerator through the feed water pump, and the boiler drain pipe is connected to the deaerator and the condenser through a third valve and a fourth valve respectively; The condenser outlet is connected to the condensate pump, and the heat storage system is respectively connected to the deaerator inlet pipe and the condensate pump outlet pipe.

2. The coal-fired unit rapid start-up system based on working fluid heat storage according to claim 1 is characterized in that: The heat storage system comprises a thermocline heat storage tank and a heat discharge pump; The upper part of the thermocline heat storage tank is connected to the outlet of the pre-pump of the adjacent machine through the first valve, and the upper part of the thermocline heat storage tank is also connected to the inlet pipeline of the deaerator through the hot water pump and the first regulating valve; The lower part of the thermocline layer heat storage tank is connected to the condenser of the adjacent machine through a second valve, and the lower part of the thermocline layer heat storage tank is also connected to the condensate pump outlet pipeline through a second regulating valve.

3. The coal-fired unit rapid start-up system based on working fluid heat storage according to claim 2 is characterized in that: The heat storage system comprises a high-temperature heat storage tank, a low-temperature heat storage tank and a heat discharge pump; The high-temperature heat storage tank is connected to the outlet of the pre-pump of the adjacent machine through the first valve, and the high-temperature heat storage tank is also connected to the inlet pipeline of the deaerator through the hot water pump and the first regulating valve; The low-temperature heat storage tank is connected to the condenser of the adjacent machine through a second valve, and the low-temperature heat storage tank is also connected to the condensate pump outlet pipeline through a second regulating valve.

4. The coal-fired unit rapid start-up system based on working fluid heat storage according to claim 2 is characterized in that: When the heat storage system adopts a thermocline heat storage tank, the heat storage process includes: Before the coal-fired unit is started, the high-temperature hot water at the outlet of the adjacent unit's front pump enters from the upper part of the thermocline layer heat storage tank and is stored in the thermocline layer heat storage tank; the cold water is discharged from the lower part of the thermocline layer heat storage tank and returned to the condenser of the adjacent unit; finally, the thermocline layer heat storage tank is filled with hot water; The thermocline heat storage tank is a low-pressure pressure vessel with a working pressure of 0.8 MPa to 1.5 MPa; low-temperature water and high-temperature water are respectively located at the lower and upper parts of the thermocline heat storage tank, forming a thermocline layer in the middle.

5. The coal-fired unit rapid start-up system based on working fluid heat storage according to any one of claims 1 to 4, characterized in that: When the heat storage system adopts a thermocline heat storage tank, the heat release process includes: When the coal-fired unit is started, the high-temperature water stored in the upper part of the thermocline heat storage tank is pressurized by the heat discharge pump and sent to the condensate pipe at the inlet of the deaerator, mixed with the main condensate and then enters the deaerator, and the hot water at the outlet of the deaerator enters the boiler through the feed water pump to warm the boiler; part of the drain water after heating returns to the deaerator, and part of the drain water returns to the condenser; part of the condensate is sent from the condenser to the lower part of the thermocline heat storage tank by the condensate pump to maintain the working medium balance; the outlet water pressure of the condensate pump should be higher than the working pressure of the thermocline heat storage tank.

6. The coal-fired unit rapid start-up system based on working fluid heat storage according to claim 3 is characterized in that: When the heat storage system uses a high-temperature heat storage tank and a low-temperature heat storage tank, the heat storage process includes: The high-temperature hot water from the outlet of the adjacent machine's front pump is stored in the high-temperature heat storage tank, and cold water is discharged from the low-temperature heat storage tank to the condenser of the adjacent machine; before the coal-fired unit is started, the high-temperature heat storage tank is filled with auxiliary steam from the adjacent machine, and the steam is slowly discharged during the heat storage process, and the low-temperature heat storage tank is filled with cold water; The high-temperature heat storage tank is a low-pressure pressure vessel, and its working pressure is 0.8MPa~1.5MPa. The low-temperature heat storage tank is a normal pressure container, and the volume of the high-temperature heat storage tank is the same as that of the low-temperature heat storage tank; high-temperature water and low-temperature water are stored in the high-temperature heat storage tank and the low-temperature heat storage tank respectively.

7. The coal-fired unit rapid start-up system based on working fluid heat storage according to any one of claims 3 or 6, characterized in that: When the heat storage system uses a high-temperature heat storage tank and a low-temperature heat storage tank, the heat release process includes: When the coal-fired unit is started, the high-temperature water stored in the high-temperature heat storage tank is pressurized by the heat discharge pump and sent to the condensate pipe at the deaerator inlet, and enters the deaerator after being mixed with the main condensate; the hot water at the deaerator outlet enters the boiler through the feed water pump to warm the boiler; part of the drain water after heating returns to the deaerator, and part of the drain water returns to the condenser; part of the condensate is sent from the condenser to the low-temperature heat storage tank by the condensate pump to maintain the working medium balance.

8. A control method for a coal-fired unit rapid start-up system based on working fluid heat storage according to any one of claims 1 to 7, characterized in that: The control method before boiler ignition includes: When the unit is started, the first valve and the second valve are closed, and the third valve, the fourth valve, the first regulating valve and the second regulating valve are opened, and the high-temperature water stored in the heat storage system is pressurized and sent to the condensate water pipeline at the inlet of the deaerator through the hot water discharge pump, and then mixed with the main condensate and enters the deaerator; the hot water at the outlet of the deaerator is sent to the boiler heater through the feed water pump; By controlling the opening of the first regulating valve, the temperature of the hot water at the outlet of the deaerator is controlled, and then the temperature rise rate of the boiler water-cooled wall is controlled, so that the temperature rise rate of the boiler water-cooled wall is within a preset temperature rise range.

9. A control method for a coal-fired unit rapid start-up system based on working fluid heat storage as claimed in claim 8, characterized in that: After the boiler is ignited, the control method includes: When the outlet water temperature of the feed water pump rises to 100°C to heat the boiler water-cooled wall at 95°C, the coal feeder starts to feed coal, the deaerator starts auxiliary steam heating, and the opening of the first regulating valve is controlled so that the average temperature rise rate of the boiler water-cooled wall is 1.0°C / min; during this process, the condensate pump is turned on, and the opening of the second regulating valve is controlled so that the water inlet and outlet of the heat storage system are consistent; When the outlet water temperature of the feed water pump rises to 145-150° C., the first regulating valve and the second regulating valve are closed, and the boiler is completely heated by fuel combustion.

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