A thermal auxiliary system and control method suitable for rapid start-stop of a pulverized coal drum boiler

Abstract

The present application belongs to the technical field of boiler, and particularly relates to a heat auxiliary system and control method suitable for quick start and stop of a pulverized coal drum boiler. The system of the present application comprises a first pipeline, a second pipeline, a third pipeline and a fourth pipeline. The first pipeline is connected from a high-temperature superheater of a neighboring boiler to a turbine pipe section of the present unit, the second pipeline is connected from an outlet header of a low-temperature superheater of the neighboring boiler to an inlet header of a low-temperature superheater of the present unit, the third pipeline is branched from an outlet header of an economizer of the neighboring boiler and a descending pipe of a drum outlet, and is then divided into two branches and connected to a feedwater pipe bypass of the present unit and a fixed discharge header of a boiler bottom of the present unit, and the fourth pipeline is connected from an inlet header of a low-temperature reheater of the neighboring boiler to an inlet header of a low-temperature reheater of the present unit. The present application provides a heat auxiliary system and control method suitable for a pulverized coal drum boiler, which can maintain parameters of each heating surface of the boiler in a hot standby state to meet the requirements of quick start and stop and deep peak regulation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of boilers, and particularly relates to a thermal auxiliary system and a control method suitable for rapid start-stop of a pulverized coal drum boiler. BACKGROUND

[0002] At present, the flexibility reform of deep load regulation and rapid start-stop of a coal-fired unit is a rigid requirement. During the start-stop process of the boiler, the thermal inertia of the boiler is large, and the rapid start-stop has a great influence on the service life of thick-walled components of the boiler. Therefore, the rapid start-stop of the boiler is limited.

[0003] The mainstream flexible load regulation technology of the coal-fired boiler in the market cannot realize full-load regulation, and the boiler has a minimum stable combustion load without oil injection, and the coal-fired boiler has a load lower limit. The cold start of the boiler is limited by many thick-walled components, and the load increasing speed of the boiler is limited. The load increasing speed of the boiler is too fast at the initial start, and the superheater, reheater and other components are prone to over-temperature, which limits the rapid start of the boiler. The long start time of the boiler causes the oil injection combustion time to be too long during the start, the ignition cost is high, and the load response is slow. The flexible load regulation required by the power grid requires large regulation amplitude and fast response speed, and the current load regulation technology in the industry is limited by the regulation amplitude and response speed. SUMMARY

[0004] In order to solve the above problems existing in the prior art, the purpose of the present application is to provide a thermal auxiliary system and a control method suitable for a pulverized coal drum boiler, which can maintain the parameters of each heating surface of the boiler in a thermal standby state to meet the requirements of rapid start-stop and deep load regulation.

[0005] The technical scheme adopted by the present application is as follows:

[0006] A thermal auxiliary system suitable for rapid start-stop of a pulverized coal drum boiler, comprising a first pipeline, a second pipeline, a third pipeline and a fourth pipeline.

[0007] The first pipeline: a section of pipeline is drawn from the outlet of the high-temperature superheater of the adjacent unit to the inlet pipe section of the steam turbine, and is connected to the outlet of the high-temperature superheater of the unit to the inlet pipe section of the steam turbine.

[0008] The second pipeline: a section of pipeline is drawn from the outlet header of the low-temperature superheater of the adjacent unit, and is connected to the inlet header of the low-temperature superheater of the unit.

[0009] The third pipeline: a section of pipeline is drawn from the outlet header of the economizer of the adjacent unit and the descending pipe of the drum, is collected, and is divided into two paths and connected to the feedwater pipe bypass of the unit and the fixed discharge header of the bottom of the unit, respectively.

[0010] The fourth pipeline: a section of pipeline is drawn from the inlet header of the low-temperature reheater of the adjacent unit, and is connected to the inlet header of the low-temperature reheater of the unit.

[0011] The present application can respond to the peak-shaving demand of the power grid at full load. After the boiler of the unit is shut down or before the cold start, hot water and steam from the adjacent unit boiler are input to maintain or heat the relevant heating surfaces, so that they are in an extremely hot standby state, ensuring that the combustion equipment of the boiler can be started at any time and the load can be quickly increased to meet the requirements of the power grid. The structure ensures that the temperature of the thick-walled components does not change dramatically during the rapid start-up and load increase of the boiler, and the stress is limited. The adjacent boiler steam also avoids overheating of the superheater and reheater caused by rapid start-up and load increase. The use of adjacent boiler steam allows the load of a single unit to be adjusted by two boilers, doubling the response speed. The present application can maintain the parameters of the heating surfaces of the boiler at a hot standby state to meet the market demand for rapid start-up and stoppage and deep peak shaving, so that the rapid start-up and stoppage and deep peak shaving have little effect on the service life of the boiler. When the present application is used, the time for conventional cold start and hot start of the boiler will be greatly shortened. The present application has high safety and considerable economic benefits.

[0012] As a preferred scheme of the present application, the first pipeline is provided with a gate valve, a regulating valve, a temperature and pressure measuring point, and a drain pipeline.

[0013] As a preferred scheme of the present application, the second pipeline is provided with a gate valve, a regulating valve, a temperature and pressure measuring point, and a drain pipeline.

[0014] As a preferred scheme of the present application, the third pipeline includes a main pipe section, one end of the main pipe section is connected to the first pipe section and the second pipe section respectively, the first pipe section is connected to the outlet header of the economizer of the adjacent unit, the second pipe section is connected to the outlet downcomer of the drum of the adjacent unit, the other end of the main pipe section is connected to the third pipe section and the fourth pipe section respectively, the third pipe section is connected to the feedwater pipe bypass of the unit, and the fourth pipe section is connected to the fixed distribution header of the furnace bottom of the unit; the first pipe section, the second pipe section, and the third pipe section are all provided with a gate valve and a regulating valve, the main pipeline is provided with a temperature and pressure measuring point, and the feedwater pipe bypass of the unit and the third pipe section are both provided with a temperature and pressure measuring point.

[0015] As a preferred scheme of the present application, the fourth pipeline is provided with a gate valve, a regulating valve, a temperature and pressure measuring point, and a drain pipeline.

[0016] As a preferred scheme of the present application, the flow capacity of the first pipeline is 30% to 50% of the BMCR of the steam of the boiler of the unit.

[0017] A thermal auxiliary control method for adapting to the rapid start-stop of a pulverized coal drum boiler, comprising the following steps:

[0018] The control method of the first pipeline: when the load of the unit needs to be reduced to below the minimum stable combustion load of the boiler, the boiler of the unit is shut down, and the insufficient steam required by the steam turbine is input from the adjacent boiler through the first pipeline; when the steam of the boiler of the unit cannot meet the requirement of the steam turbine, the regulating valve on the first pipeline is cut off, and the steam generated by the boiler is discharged through the high-low bypass; when the load required by the power grid is higher than the regulating capacity of the first pipeline, the boiler of the unit is started quickly to meet the high load demand of the power grid, and after the boiler of the unit is started and the steam parameter reaches the requirement of the steam turbine, the steam turbine is connected, and the regulating valve of the first pipeline is adjusted to gradually reduce the steam supply of the adjacent unit until the first pipeline is closed;

[0019] The control method of the second pipeline: in the process that the boiler of the unit is cut off and the temperature of the furnace continuously decreases, the steam at the outlet of the low-temperature superheater of the adjacent unit is introduced through the second pipeline to maintain the steam temperature and pressure of the subsequent superheaters from greatly decreasing;

[0020] The control method of the third pipeline: after the fuel of the boiler of the unit is cut off, the temperature of the furnace decreases, the regulating valve of the third pipeline is opened, and the inlet water temperature of the water wall and the economizer of the furnace of the unit is moderately increased; when the temperature of the furnace continues to decrease, the effective flow of the feedwater pump of the unit is gradually reduced until the pump is closed, and the feedwater is completely supplied by the adjacent unit;

[0021] The control method of the fourth pipeline: when the temperature of the low-temperature reheater of the unit decreases, a steam is introduced from the inlet header of the low-temperature reheater of the adjacent unit into the inlet header of the low-temperature reheater of the unit through the fourth pipeline.

[0022] As a preferred scheme of the present application, in the control method of the first pipeline, the gate valves at both ends of the regulating valve of the first pipeline maintain a normal open state, when the power grid needs to rapidly increase or decrease the load, the two boilers simultaneously respond, and then the opening degree of the regulating valve on the first pipeline is controlled to double the load response speed of a single unit.

[0023] As a preferred scheme of the present application, in the control method of the second pipeline, when the steam at the outlet of the low-temperature superheater of the adjacent unit is introduced through the second pipeline to maintain the steam temperature and pressure of the subsequent superheaters from greatly decreasing, the roof superheater drain of the unit is opened, with the decrease of the temperature of the roof superheater, the steam in the inlet header of the low-temperature superheater is reversely filled into the roof superheater to maintain the pressure of the entire superheated steam pipeline.

[0024] The present application has the following beneficial effects:

[0025] The application can respond to the peak-shaving demand of the power grid at full load by stopping the combustion equipment of the boiler of the unit and maintaining the operation of the turbine and the generator below the minimum stable combustion load of the turbine through the first pipeline, the second pipeline, the third pipeline and the fourth pipeline. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of the application.

[0027] In the figure: 1-turbine; 2-high temperature superheater; 3-low temperature superheater; 4-steam drum; 5-furnace water wall; 6-economizer; 7-reheater; s1-first pipeline; s2-second pipeline; s3-third pipeline; s4-fourth pipeline; s31-first pipe section; s32-second pipe section; s33-third pipe section; s34-fourth pipe section. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme of the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. The components of the embodiments of the application described and shown in the drawings can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the application without creative labor are within the scope of protection of the application. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0030] As shown in Figure 1 , the unit and the adjacent unit each include an economizer 6, a furnace water wall 5, a steam drum 4, a low temperature superheater 3, a high temperature superheater 2, a turbine 1 and a reheater 7 arranged in sequence.

[0031] The thermal auxiliary system of the embodiment is suitable for the quick start and stop of the coal-fired drum boiler, and comprises a first pipeline s1, a second pipeline s2, a third pipeline s3 and a fourth pipeline s4; the first pipeline s1 is a pipeline drawn from the outlet of the high-temperature superheater 2 of the adjacent unit to the inlet pipe section of the steam turbine 1, and is connected to the outlet of the high-temperature superheater 2 of the unit to the inlet pipe section of the steam turbine 1; the second pipeline s2 is a pipeline drawn from the outlet header of the low-temperature superheater 3 of the adjacent unit, and is connected to the inlet header of the low-temperature superheater 3 of the unit; the third pipeline s3 is a pipeline drawn from the outlet header of the economizer 6 of the adjacent unit and the descending pipe of the drum 4, and is divided into two branches after being collected and connected to the feedwater pipe bypass of the unit and the bottom fixed discharge header of the unit respectively; and the fourth pipeline s4 is a pipeline drawn from the inlet header of the low-temperature reheater 7 of the adjacent unit, and is connected to the inlet header of the low-temperature reheater 7 of the unit.

[0032] Two gate valves, one regulating valve, temperature and pressure measuring points and a drain pipeline are arranged on the first pipeline s1, and the flow capacity of the first pipeline s1 is 30% to 50% BMCR of the steam quantity of the boiler of the unit. Two gate valves, one regulating valve, temperature and pressure measuring points and a drain pipeline are arranged on the second pipeline s2. The third pipeline s3 comprises a main pipe section, one end of the main pipe section is connected to the first pipe section s31 and the second pipe section s32 respectively, the first pipe section s31 is connected to the outlet header of the economizer 6 of the adjacent unit, and the second pipe section s32 is connected to the descending pipe of the drum 4 of the adjacent unit, the other end of the main pipe section is connected to the third pipe section s33 and the fourth pipe section s34 respectively, the third pipe section s33 is connected to the feedwater pipe bypass of the unit, and the fourth pipe section s34 is connected to the bottom fixed discharge header of the unit; two gate valves and one regulating valve are arranged on the first pipe section s31, the second pipe section s32 and the third pipe section s33 respectively, temperature and pressure measuring points are arranged on the main pipeline, and temperature and pressure measuring points are arranged on the feedwater pipe bypass of the unit and the third pipe section s33. Two gate valves, one regulating valve, temperature and pressure measuring points and a drain pipeline are arranged on the fourth pipeline s4.

[0033] The present application can respond to the peak demand of the power grid at full load. After the boiler of the present unit is shut down or before the cold start, the hot water and steam from the adjacent unit are input to maintain or heat the relevant heating surface, so that the boiler combustion equipment can be started at any time, the load can be quickly increased, and the requirement of the power grid can be responded. The structure ensures that the temperature of the thick-walled component does not change dramatically when the boiler is started and the load is increased, and the stress is limited. The adjacent boiler steam can avoid the overheating of the superheater and reheater 7 caused by rapid start and load increase. The use of adjacent boiler steam can double the response speed of single unit load adjustment through two boilers. The present application can maintain the parameters of the heating surface of the boiler at a hot standby state to meet the market demand for rapid start and stop and deep peak regulation, so that the rapid start and stop and deep peak regulation have little effect on the service life of the boiler. When the present application is used, the time of conventional cold start and hot start of the boiler will be greatly shortened. The present application has high safety and considerable economic benefits.

[0034] The thermal auxiliary control method for the pulverized coal drum boiler rapid start and stop of the present embodiment comprises the following steps:

[0035] The control method of the first pipeline s1: when the load of the present unit needs to be reduced below the minimum stable combustion load of the boiler, the boiler of the present unit is shut down, the steam production is gradually reduced, and the insufficient part of the steam required by the steam turbine 1 is input from the adjacent boiler through the pipeline to maintain the steam temperature, pressure and flow required by the steam turbine 1. The load peak of the power grid is completely controlled by the regulating valve of the first pipeline s1. When the steam of the boiler of the present unit cannot meet the requirement of the steam turbine 1, the steam produced by the boiler is discharged from the high-low bypass. When the load required by the power grid of the present unit is higher than the adjustment capacity of the connecting pipe, the boiler of the present unit needs to be started quickly to meet the high load demand of the power grid. After the boiler of the present unit is started and the steam parameters meet the requirements of the steam turbine 1, the steam turbine 1 is connected, and the regulating valve of the first pipeline s1 is adjusted to gradually reduce the steam supply of the adjacent boiler until it is closed. The gate valves at both ends of the regulating valve of the first pipeline s1 are in a normal open state, and when the power grid needs to quickly increase or decrease the load, the two boilers can respond at the same time, and then the load response speed of single unit is doubled through the control of the opening degree of the valve. If a large pipeline is used and the system is completely changed to a mother pipe system, the control strategy is referred to the mother pipe control system.

[0036] The control method of the second pipeline s2: in the process of cutting off the fuel of the furnace and continuously reducing the furnace temperature, the steam from the low-temperature superheater 3 of the adjacent furnace is introduced through the second pipeline s2 to maintain the steam temperature and pressure of the subsequent superheaters from greatly reducing, and the minimum temperature is controlled to be 20℃ lower than the extraction steam temperature (determined according to the specific project), and the pressure is determined according to the specific project parameters. The drain of the ceiling superheater is opened, and with the decrease of the temperature of the ceiling superheater, the steam in the inlet header of the low-temperature superheater 3 will be reversely filled into the ceiling superheater, thereby maintaining the pressure of the entire superheated steam pipeline.

[0037] The control method of the third pipeline s3: after cutting off the fuel of the furnace, the water level of the steam drum 4 is maintained, and the feed water is continuously supplied. In the case that the steam parameters do not meet the requirements, the throttle valve on the first pipeline s1 entering the steam turbine 1 is cut off, the high-low bypass is connected to the condenser, and the main steam pressure is maintained from greatly reducing. With the decrease of the flue gas temperature of the boiler, the steam production rate of the furnace water wall 5 decreases, and the temperature of each heating surface gradually decreases. In order to ensure that the furnace temperature does not decrease too fast, the throttle valve of the third pipeline s3 is opened, and the inlet water temperature of the furnace water wall 5 and the economizer 6 of the furnace is moderately increased. When the furnace temperature continues to decrease, the effective flow of the feed water pump of the furnace is gradually reduced (the flow of the feed water pump is deducted from the circulation flow), until the feed water pump is closed, and the feed water is completely supplied by the adjacent furnace. When the furnace temperature further decreases, the temperature of the steam drum 4 is maintained at 20℃ lower than the outlet temperature of the economizer 6 of the adjacent furnace (determined according to the project).

[0038] The control method of the fourth pipeline s4: when the temperature of the low-temperature reheater 7 of the unit decreases, a steam is introduced from the inlet header of the low-temperature reheater 7 of the adjacent unit through the fourth pipeline s4 to enter the inlet header of the low-temperature reheater 7 of the unit, so as to adjust the temperature and pressure of the reheater 7 of the furnace, and the extraction steam temperature is not decreased by more than 20℃ (determined according to the specific project).

[0039] Operation strategy:

[0040] Shutdown and hot standby strategy: When the unit load drops to 40% BMCR, start to prepare for shutdown standby. Assume the adjacent unit is running at 40% BMCR, and the relevant parameters are at design values. When the unit load drops below 40% BMCR, the minimum stable combustion load, start to shut down the unit. Gradually reduce the coal feeder coal supply, maintain the furnace air volume, gradually empty the coal mill and powder pipe, cut off the fuel, extinguish the furnace, complete the furnace purging, stop the air blower, close the flue gas damper, and the furnace is muffled. The furnace coal is reduced and extinguished, the steam capacity is reduced, the high-temperature superheater 2 outlet superheated steam pressure is reduced, the valve of the first pipeline s1 is opened, the turbine 1 inlet pressure is maintained, and the unit load is ensured. The superheated steam flow of the unit continues to decrease, and the steam drum 4 pressure 8.56 MPa (allowable -0.5 MPa) remains unchanged (saturated temperature 300°C). When the unit flow drops below 50 t / h (tentative), the valve from the high-temperature superheater 2 outlet to the turbine 1 is cut off, and the high-temperature superheater 2 outlet steam is sent to the condenser through the high-low bypass, and the valve opening is controlled to maintain the pressure from falling too much. The turbine 1 is completely maintained in operation and peak regulation by the first pipeline s1 from the adjacent unit, and the peak regulation load is 0-40% BMCR.

[0041] Boiler feedwater control maintains the steam drum 4 water level, and the third pipeline s3 is used to extract water (258°C) from the adjacent unit economizer 6 outlet to control the temperature of the unit economizer 6 outlet to 258°C (allowable -20°C). After the subsequent feedwater pump is below the minimum flow, all feedwater is supplied from the third pipeline s3 from the adjacent unit. The furnace temperature further decreases, and the furnace steam production decreases accordingly. When the furnace temperature (flue gas temperature probe) drops to 420°C (adjusted according to the situation), the third pipeline s3 extracts saturated water from the adjacent unit steam drum 4 outlet drop pipe (8.56 MPa, 300°C) into the unit economizer 6 and the fixed discharge header at the bottom of the furnace, and the water is supplied from the economizer 6 and the bottom water-cooled wall lower header to the furnace water-cooled wall 5 to maintain the steam drum 4 pressure at 8.56 MPa (allowable -1 MPa). If the water level is too high, it will be discharged from the steam drum 4, and the steam drum 4 water level is maintained. The ceiling superheater drain is appropriately opened. When the vertical low-temperature superheater 3 inlet flue gas temperature is lower than 500°C (determined according to the situation, if the superheated steam pipeline cannot be maintained, it can be opened earlier), the low-temperature superheater 3 outlet header of the adjacent unit is introduced into the low-temperature superheater 3 inlet header of the unit to maintain the superheated steam pressure, and the high-low bypass is slightly opened to allow low steam flow through the low-temperature superheater 3 and the high-temperature superheater 2 to maintain the steam temperature. When the unit reheater 7 wall temperature rises, or the low-reheat inlet flue gas temperature drops to 500°C, open the fourth pipeline s4 to maintain a low flow to maintain the reheater 7 steam temperature.

[0042] Stable balance after standby state: hearth temperature 300 ℃ (-20 ℃), drum 4 temperature 300 ℃ (-20 ℃) pressure 8.56 MPa (allow -1 MPa), slightly lower temperature ceiling superheater, low temperature superheater 3, high temperature superheater 2 temperature 405 ℃ (-20 ℃).

[0043] Ignition start operation strategy: before the preparation of the boiler ignition start, each system standby (oil system, wind system, pulverizing system, etc.), open the flue gas baffle, send the induced draft fan start, oil gun ignition (if there is a micro oil or plasma ignition system, according to its operation requirements control operation), put into the coal burner. The flue gas temperature of the furnace rises rapidly, the furnace water wall 5 starts to produce steam, the third pipeline s3 continues to supply water from the adjacent boiler economizer 6 outlet, closes the bottom of the fixed valve, stops the water supply from the bottom of the distribution header, only from the economizer 6. The second pipeline s2 superheated steam flow is controlled according to the wall temperature of each stage superheater, until closed. The fourth pipeline s4 is controlled according to the wall temperature of the reheater 7 of the boiler, until closed. According to the outlet steam temperature of the economizer 6 to ensure that it is lower than the boiling point 20 ℃, open the feed water pump of the boiler, gradually close the third pipeline s3 water, until closed. The steam parameters gradually rise, and the parameters are qualified after the steam is combined. After the steam supply of the boiler is sufficient, the first pipeline s1 is closed.

[0044] The present application is not limited to the above-mentioned optional embodiments, anyone can derive other various forms of products under the inspiration of the present application, but regardless of any changes in its shape or structure, any technical solutions falling within the scope of the claims of the present application fall within the scope of the present application.

Claims

1. A heat assisted system for quick start and stop of a pulverized coal drum boiler, characterized in that: The first pipeline (s1), the second pipeline (s2), the third pipeline (s3) and the fourth pipeline (s4) are included. The first pipeline (s1) is a pipeline from the high-temperature superheater (2) outlet of the adjacent unit to the turbine (1) inlet pipe section, and is connected to the high-temperature superheater (2) outlet to the turbine (1) inlet pipe section of the unit. The second pipeline (s2) is a pipeline from the low-temperature superheater (3) outlet header of the adjacent unit, and is connected to the inlet header of the low-temperature superheater (3) of the unit. The third pipeline (s3) is a pipeline from the economizer (6) outlet header and the drum (4) outlet descending pipe of the adjacent unit, and is connected to the feedwater pipe bypass of the unit and the bottom fixed discharge header of the unit. The fourth pipeline (s4) is a pipeline from the low-temperature reheater (7) inlet header of the adjacent unit, and is connected to the inlet header of the low-temperature reheater (7) of the unit.

2. The thermal auxiliary system for quick start and stop of a coal-fired drum boiler according to claim 1, characterized in that: The first pipeline (s1) is provided with a gate valve, a regulating valve, a temperature and pressure measuring point and a drainage pipeline.

3. The thermal auxiliary system for quick start and stop of a coal-fired drum boiler according to claim 1, characterized in that: The second pipeline (s2) is provided with a gate valve, a regulating valve, a temperature and pressure measuring point and a drainage pipeline.

4. The thermal auxiliary system for quick start and stop of a coal-fired drum boiler according to claim 1, characterized in that: The third pipeline (s3) includes a main pipe section, one end of the main pipe section is connected with a first pipe section (s31) and a second pipe section (s32) respectively, the first pipe section (s31) is connected to the economizer (6) outlet header of the adjacent unit, the second pipe section (s32) is connected to the drum (4) outlet descending pipe of the adjacent unit, the other end of the main pipe section is connected with a third pipe section (s33) and a fourth pipe section (s34) respectively, the third pipe section (s33) is connected to the feedwater pipe bypass of the unit, and the fourth pipe section (s34) is connected to the bottom fixed discharge header of the unit; the first pipe section (s31), the second pipe section (s32) and the third pipe section (s33) are all provided with a gate valve and a regulating valve, the main pipeline is provided with a temperature and pressure measuring point, and the feedwater pipe bypass of the unit and the third pipe section (s33) are both provided with a temperature and pressure measuring point.

5. The thermal auxiliary system for quick start and stop of a coal-fired drum boiler according to claim 1, characterized in that: The fourth pipeline (s4) is provided with a gate valve, a regulating valve, a temperature and pressure measuring point and a drainage pipeline.

6. The thermal auxiliary system for quick start and stop of a coal-fired drum boiler according to claim 1, characterized in that: The flow capacity of the first pipeline (s1) is 30% to 50% BMCR of the steam quantity of the unit boiler.

7. A thermal auxiliary control method for fast start and stop of a pulverized coal drum boiler using the system of claim 1, characterized in that: The following steps are included: The control method of the first pipeline (s1) is that when the unit load needs to be reduced to below the minimum stable combustion load of the boiler, the unit boiler is shut down, and the insufficient steam required by the turbine (1) is input from the adjacent boiler through the first pipeline (s1); when the unit boiler steam cannot meet the required steam of the unit turbine (1), the regulating valve on the first pipeline (s1) is cut off, and the steam of the boiler is discharged from the high-low bypass; when the required load of the unit power grid is higher than the regulating capacity of the first pipeline (s1), the unit boiler is started quickly to meet the high load demand of the power grid, and after the unit boiler is started, the steam parameters reach the requirements of the main steam, and the unit turbine (1) is connected, and the regulating valve of the first pipeline (s1) is adjusted to gradually reduce the steam supply of the adjacent unit until the first pipeline (s1) is closed. The control method of the second pipeline (s2) is that in the process of cutting off the fuel of the boiler of the unit and continuously reducing the temperature of the furnace, the steam at the outlet of the low-temperature superheater (3) of the adjacent unit is introduced through the second pipeline (s2) to maintain the steam temperature and pressure of the subsequent superheaters from greatly reducing; The control method of the third pipeline (s3) is that after cutting off the fuel of the boiler of the unit, the temperature of the furnace is reduced, the regulating valve of the third pipeline (s3) is opened, and the water inlet temperature of the water wall (5) and the economizer (6) of the furnace of the unit is moderately increased; when the temperature of the furnace continues to reduce, the effective flow of the feed water pump of the unit is gradually reduced until it is closed, and the feed water is completely supplied by the adjacent unit; The control method of the fourth pipeline (s4) is that when the temperature of the low-temperature reheater (7) of the unit is reduced, a steam is introduced from the inlet header of the low-temperature reheater (7) of the adjacent unit through the fourth pipeline (s4) to enter the inlet header of the low-temperature reheater (7) of the unit.

8. The thermal auxiliary control method for quick start and stop of a coal-fired drum boiler according to claim 7, characterized in that: In the control method of the first pipeline (s1), the gate valves at both ends of the regulating valve of the first pipeline (s1) maintain the open state, when the power grid needs to rapidly increase or decrease the load, the two boilers simultaneously respond, and then the opening degree of the regulating valve on the first pipeline (s1) is controlled to make the load response speed of a single unit doubled.

9. The thermal auxiliary control method for quick start and stop of a coal-fired drum boiler according to claim 7, characterized in that: In the control method of the second pipeline (s2), when the steam at the outlet of the low-temperature superheater (3) of the adjacent unit is introduced through the second pipeline (s2) to maintain the steam temperature and pressure of the subsequent superheaters from greatly reducing, the roof superheater drain of the unit is opened, and with the reduction of the temperature of the roof superheater, the steam in the inlet header of the low-temperature superheater (3) is reversely filled into the roof superheater to maintain the pressure of the entire superheated steam pipeline.

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