CN113587075B

CN113587075B - Control method for slowing down generation and falling of oxide skin in heating pipe of power station unit

Info

Publication number: CN113587075B
Application number: CN202110703449.4A
Authority: CN
Inventors: 张建华; 李小健; 韩宝庚
Original assignee: Huaneng Chaohu Power Generation Co Ltd
Current assignee: Huaneng Chaohu Power Generation Co Ltd
Priority date: 2021-06-24
Filing date: 2021-06-24
Publication date: 2022-04-01
Anticipated expiration: 2041-06-24
Also published as: CN113587075A

Abstract

The invention discloses a control method for slowing down the generation and falling of oxide skin in a heating pipe of a power station unit, and S1, a boiler is started to heat the boiler, the process from a cold state to a warm state of the boiler to a hot state is carried out, the unit is started at the same time, and the inside of the unit is converted into a dry state from a warm state to a wet state in the running process of the unit. According to the invention, in the process of monitoring the temperature of each pipe wall of the partition screen superheater, the high-temperature superheater and the high-temperature reheater, the detection of the wall temperature of the boiler is realized through the arrangement of the alarm component, the monitoring effect of the alarm component can be effectively realized by utilizing the structural design mode of the alarm component, meanwhile, when the wall temperature exceeds a threshold value, the regulation component is pushed to rotate, in the rotation process of the regulation component, the expansion of a flow port of the water regulating valve is realized, the synchronization of water flow is promoted, the temperature reduction work of the water regulating valve is promoted, and the conditions of pipe wall overtemperature and pipe explosion are effectively avoided.

Description

Control method for slowing down generation and falling of oxide skin in heating pipe of power station unit

Technical Field

The invention relates to the technical field of power station units, in particular to a control method for slowing down the generation and falling of oxide skin in a heating pipe of a power station unit.

Background

The tube materials of the inner heating surfaces of the boiler divided screen superheater, the high-temperature superheater and the high-temperature reheater are T91, TP347H, SUP304H, HR3C and T122, the thickening of the high-temperature oxide scale on the inner wall of the furnace tube after the long-period operation of the unit is inevitable, and if the tube wall is over-temperature, the generation of the oxide scale is accelerated. Because the high-temperature oxide skin and the matrix have different thermal expansion coefficients, when the unit is started or stopped and the temperature of the furnace tube is greatly changed, the oxide skin is likely to fall off to block the tube explosion. The conditions of high pipe wall temperature and pipe explosion caused by blockage of foreign matters left after capital construction of an end pipe of a superheater header are repeated in the starting process of a unit;

based on the situation, a control method for slowing down the generation and the falling of oxide skin in the heating pipe of the power station unit is designed to solve the problems.

Disclosure of Invention

The invention aims to solve the problem that oxide skin falls off to block and explode the tube when the temperature of the furnace tube changes greatly in the prior art. The conditions of high pipe wall temperature and pipe explosion caused by the blockage of foreign matters left by capital construction of an end pipe of a superheater header in the starting process of a unit occur for many times, and the control method for slowing down the generation and the falling of oxide skin in a heated pipe of a power station unit is provided.

In order to achieve the purpose, the invention adopts the following technical scheme:

a control method for slowing down the generation and the falling of oxide skin in a heating pipe of a power station unit comprises the following steps;

s1, starting a boiler to heat the boiler, starting a unit simultaneously in the process that the boiler is changed from a cold state to a warm state to a hot state, and changing the temperature state of the inside of the unit into a wet state and then into a dry state in the running process of the unit;

s2, in the operation process, the temperature of each pipe wall of the partition screen superheater, the high-temperature superheater and the high-temperature reheater needs to be monitored, and in the monitoring process, an alarm mechanism carries out monitoring execution;

and S3, stopping the unit, after the boiler is tightly closed for 36 hours and the water is discharged, if the maintenance is needed, establishing a channel of the air and smoke system, opening the movable blades of the air feeder and the static blades of the induced draft fan at the opening of 10-20-30-40-60-80-100% every 30 minutes, and naturally ventilating and cooling the boiler.

Preferably, in the S1, a water source is firstly added into the boiler, and the water source has the quality standard of PH value of 9.2-9.6, Fe being less than or equal to 50 mu g/L, SiO2 being less than or equal to 30 mu g/L, and electric conductivity being less than or equal to 0.65 mu S/cm.

Preferably, in S2, the alarm mechanism includes a wall body and a temperature reduction pipe spirally disposed on an outer side wall of the wall body, the temperature reduction work on the wall body is achieved through the temperature reduction pipe, a communication pipe is mounted on the outer side wall of the temperature reduction pipe, a water regulation valve is mounted on a side wall of the communication pipe, and a regulation assembly for regulating the flow of water flow is fixedly disposed at a lower end of the water regulation valve;

the utility model discloses a water flow regulating device, including wall body, warning subassembly, regulating component, temperature measurement and regulation of rivers, nested being provided with the warning subassembly on the lateral wall of wall body, warning subassembly and regulating component fixed connection set up, and the cooperation of warning subassembly and regulating component is used, has realized the temperature measurement to the wall body is inside and has realized the regulation work to the rivers size, the inside of warning subassembly is provided with the warning contact the start-up early warning of warning contact can be controlled in the time of the operation of warning subassembly internal mechanism.

Preferably, the outside of the water regulating valve is connected with a water pump, so that a circulating temperature-reducing water source is conveyed to the communicating pipeline and the temperature-reducing pipeline.

Preferably, the adjusting assembly comprises a driven meshing gear fixedly arranged inside the alarm assembly and an adjusting rod rotatably arranged at the upper end of the alarm assembly, the upper end of the adjusting rod is fixedly arranged with a rotating valve rod for adjusting the control flow of the water valve, the lower end of the adjusting rod is fixedly provided with an adjusting bar gear, and the lower end of the adjusting bar gear is meshed with the driven meshing gear.

Preferably, the warning subassembly sets up the temperature measurement chamber on the wall body including the nestification and fixes the thermal-insulated outer wall of establishing on the temperature measurement chamber, the internally mounted of thermal-insulated outer wall has the temperature tube, the sealed slip of thermal-insulated outer wall internal seal is provided with the promotion sliding plug, the side wall mounting that promotes the sliding plug is provided with and is used for measuring component, be provided with the scale on measuring component's the lateral wall, the thermal-insulated outer wall internal fixation is provided with the slip piston that is used for promoting driven meshing gear removal, it directly sets up through first spring coupling with the slip piston to promote the sliding plug.

Preferably, the alarm contact element is electrically connected with an external buzzer alarm, and the alarm contact element is triggered by pushing the sliding plug to move, so that the buzzer alarm starts to alarm.

Preferably, the temperature measurement cavity is spherically arranged, and the temperature measurement cavity is filled with easily expandable gas, so that accurate induction on the internal temperature of the wall body is realized, and effective measurement on the internal temperature of the wall body is realized.

Compared with the prior art, the invention has the beneficial effects that:

in the process of monitoring the temperature of each pipe wall of the partition screen superheater, the high-temperature superheater and the high-temperature reheater, the detection of the wall temperature of the boiler is realized through the arrangement of the alarm assembly, the monitoring effect of the alarm assembly can be effectively realized by utilizing the structural design mode of the alarm assembly, and meanwhile, when the wall temperature exceeds a threshold value, the adjustment assembly is pushed to rotate;

the temperature measuring cavity can receive the conduction of the temperature inside the wall body by being nested on the side wall of the wall body, the accuracy of the temperature conduction is further improved by the nested design, and in the process of increasing the temperature inside the temperature measuring cavity, the gas inside the wall body is promoted to begin to expand, the sliding plug is pushed to move, the driven meshing gear is driven to move, and meanwhile, the first spring realizes the damping work of the sliding plug;

when the detected temperature is in a threshold value, the driven meshing gear moves to a critical point where the driven meshing gear is in contact with or not in contact with the adjusting bar gear, when the temperature continues to rise, the expanded gas in the temperature measuring cavity pushes the driven meshing gear to continue moving, and because the driven meshing gear is meshed with the adjusting bar gear, the driven meshing gear drives the adjusting bar gear to rotate in the moving process of the driven meshing gear, so that the adjusting rod is promoted to start to rotate, the size of a valve port is adjusted, and the water flow in the water adjusting valve is adjusted;

through the arrangement of the measuring assembly, the observation and monitoring of the temperature inside the wall body are realized in the process of pushing the sliding plug to move, when the sliding plug is pushed to move to be in contact with the alarm contact member, the temperature inside the wall body exceeds the early warning threshold value at the moment, the early warning work of external workers is further realized, the operation of a boiler and a unit needs to be adjusted in time, and the condition of pipe explosion is avoided;

through the setting of above-mentioned structure, can effectually realize the control to the pipe wall temperature, when the pipe wall temperature surpassed the threshold value, can improve the valve port size of adjusting the water valve simultaneously, promote the promotion of desuperheating water flow, promote the high efficiency of desuperheating work to go on, also can realize simultaneously the early warning to the staff, avoided the cinder to drop and blockked up the emergence of bursting pipe.

Drawings

FIG. 1 is a schematic structural diagram of a control method for slowing down the generation and the falling of oxide skin in a heated pipe of a power station unit according to the present invention;

FIG. 2 is an enlarged structural view of a control method for slowing down the generation and the falling of oxide skin in a heating pipe of a power station unit, which is provided by the invention;

FIG. 3 is a schematic structural diagram of a tube wall and a desuperheating pipeline of a control method for slowing down the generation and falling of oxide skin in a heated tube of a power station unit, provided by the invention;

FIG. 4 is a diagram showing an early warning state of a control method for slowing down the generation and the falling of oxide skin in a heated pipe of a power station unit according to the present invention;

fig. 5 is an enlarged view showing an early warning state of the control method for slowing down the generation and the falling of the oxide skin in the heating pipe of the power station unit.

In the figure: the device comprises a pipe wall 1, a temperature-reducing pipeline 2, an alarm component 3, a temperature-measuring cavity 301, a temperature-measuring pipe 302, a heat-insulating outer wall 303, a sliding plug 304, a first spring 305, a sliding piston 306, a measuring component 307, a communicating pipeline 4, a water-regulating valve 5, a water-regulating rod 6, a strip gear 601, a driven meshing gear 602, scales 7 and an alarm contact 8.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1-5, a control method for slowing down the generation and the falling of oxide skin in a heating pipe of a power station unit comprises the following steps;

s1, starting a boiler to heat the boiler, starting a unit simultaneously in the process that the boiler is changed from a cold state to a warm state to a hot state, and changing the temperature state of the inside of the unit into a wet state and then into a dry state in the running process of the unit; in S1, firstly, adding a water source into the boiler, wherein the water source has the quality standard of PH value of 9.2-9.6, Fe content of less than or equal to 50 mug/L, SiO2 of less than or equal to 30 mug/L and electric conductivity of less than or equal to 0.65 mug/cm in S1;

in S2, the alarm mechanism comprises a wall body 1 and a temperature reduction pipeline 2 spirally arranged on the outer side wall of the wall body 1, temperature reduction work on the wall body 1 is realized through the temperature reduction pipeline 2, a communicating pipeline 4 is arranged on the outer side wall of the temperature reduction pipeline 2, a water regulating valve 5 is arranged on the side wall of the communicating pipeline 4, the outside of the water regulating valve 5 is connected with a water pump, a circulating temperature reduction water source is conveyed to the communicating pipeline 4 and the temperature reduction pipeline 2, an external water pump is started, water flow can be driven, and the temperature reduction pipeline 2 is spirally arranged on the outer wall of the wall body 1, so that the temperature reduction work on the wall can be effectively realized in the circulating flow process of the temperature reduction water;

the lower end of the water regulating valve 5 is fixedly provided with a regulating component for regulating the flow of water flow;

the side wall of the wall body 1 is provided with the alarm component 3 in a nested mode, the alarm component 3 is fixedly connected with the adjusting component, the alarm component 3 is matched with the adjusting component for use, temperature measurement of the interior of the wall body 1 is achieved, and adjustment of water flow is achieved, the alarm contact element 8 is arranged in the alarm component 3, and when the internal mechanism of the alarm component 3 runs, starting and early warning of the alarm contact element 8 can be controlled;

in the process of monitoring the temperature of each pipe wall of the partition screen superheater, the high-temperature superheater and the high-temperature reheater, the wall temperature of the boiler is detected through the arrangement of the alarm component 3, the monitoring effect of the alarm component 3 can be effectively realized by utilizing the structural design mode of the alarm component 3, meanwhile, when the wall temperature exceeds a threshold value, the adjusting component is pushed to rotate, in the rotating process of the adjusting component, the expansion of a flow port of the water adjusting valve 5 is realized, the synchronization of water flow is promoted, the temperature reduction work of the adjusting valve is promoted, and the conditions of pipe wall overtemperature and pipe explosion are effectively avoided;

further, the adjusting assembly comprises a driven meshing gear 602 fixedly arranged inside the alarm assembly 3 and an adjusting rod 6 rotatably arranged at the upper end of the alarm assembly 3, the upper end of the adjusting rod 601 is fixedly arranged with a rotating valve rod for adjusting the flow control size of the water valve 5, the lower end of the adjusting rod 6 is fixedly provided with an adjusting bar gear 601, and the lower end of the adjusting bar gear 601 is meshed with the driven meshing gear 602;

the alarm component 3 comprises a temperature measuring cavity 301 which is nested on the wall body 1 and a heat insulation outer wall 303 which is fixedly arranged on the temperature measuring cavity 301, a temperature measuring tube 302 is arranged inside the heat insulation outer wall 303, a pushing sliding plug 304 is arranged in the heat insulation outer wall 303 in a sealing and sliding mode, a measuring component 307 for measuring is arranged on the side wall of the pushing sliding plug 304 in a mounting mode, a sliding piston 306 for pushing the driven meshing gear 602 to move is fixedly arranged in the heat insulation outer wall 303 of a scale 7, and the pushing sliding plug 304 and the sliding piston 306 are directly connected through a first spring 305;

the alarm contact element 8 is electrically connected with an external buzzer alarm, and the sliding plug 304 is pushed to move, so that the alarm contact element 8 is touched, and the buzzer alarm starts to alarm;

the temperature measuring cavity 301 is arranged in a spherical shape, and the temperature measuring cavity 301 is filled with the easily expandable gas, so that the accurate sensing of the temperature inside the wall body 1 is realized, and the effective measurement of the temperature inside the wall body 1 is realized;

the temperature measurement cavity 301 can receive the conduction of the temperature inside the wall body 1 by being nested on the side wall of the wall body 1, the accuracy of the temperature conduction is further improved by the nested design, and in the process that the temperature inside the temperature measurement cavity 301 rises, the gas inside the wall body 1 is promoted to begin to expand to push the sliding plug 304 to move so as to drive the driven meshing gear 602 to move, and meanwhile, the first spring 305 realizes the damping work of the sliding plug 304;

when the detected temperature is at a threshold value, the driven meshing gear 602 moves to a critical point where the driven meshing gear is in contact with or not in contact with the adjusting bar gear 601, when the temperature continues to rise, the expanded gas in the temperature measuring cavity 301 pushes the driven meshing gear 602 to continue to move, and because the driven meshing gear 602 is meshed with the adjusting bar gear 601, the driven meshing gear 602 drives the adjusting bar gear 601 to rotate in the moving process, so that the adjusting rod 6 is promoted to start to rotate, the size of a valve port is adjusted, and the flow of water in the adjusting water valve 5 is adjusted;

through the arrangement of the measuring component 7, the observation and monitoring of the internal temperature of the wall body 1 are realized in the process of pushing the sliding plug 304 to move, when the sliding plug 304 is pushed to move to be in contact with the alarm contact member 8, the temperature in the wall body 1 exceeds the early warning threshold value, the early warning work of external workers is further realized, the operation of a boiler and a unit needs to be adjusted in time, and the condition of pipe explosion is avoided;

through the arrangement of the structure, the monitoring on the temperature of the pipe wall can be effectively realized, and meanwhile, when the temperature of the pipe wall exceeds a threshold value, the size of a valve port of 5 can be increased simultaneously, the flow of the desuperheating water is promoted to be increased, the high-efficiency desuperheating work is promoted to be carried out, meanwhile, the early warning on workers can be realized, and the phenomenon that the pipe explosion is blocked due to the falling of oxide skin is avoided;

s3, stopping the unit, after the boiler is tightly closed for 36 hours and the water is discharged, if the maintenance is needed, establishing a channel of a wind and smoke system, opening a movable blade of a blower and a static blade of an induced draft fan at the opening of 10-20-30-40-60-80-100% every 30 minutes, and naturally ventilating and cooling the boiler;

in order to facilitate understanding of the application scene and the working principle of the scheme, detailed description is carried out through the specific working conditions of the boiler and the unit below;

starting of the unit

1. The quality of boiler ignition feed water is qualified (the PH value is 9.2-9.6, the Fe is less than or equal to 50 mu g/L, SiO2 and less than or equal to 30 mu g/L, and the conductivity is less than or equal to 0.65 mu s/cm);

2. in the cold starting process of the boiler, after the boiler is ignited and pressurized, the steam turbine bypass automatic mode is adopted, the temperature rising rate of main steam is controlled to be not more than 1.25 ℃/min, the pressure rising rate of the main steam pressure is not more than 0.028MPa/min, and the gas releasing valves of the superheater and the reheater are closed after the main steam pressure rises to 0.5 MPa;

3. in the warm-state and hot-state starting processes of the boiler, in order to prevent the metal temperature of a heating surface from being reduced, the starting of an air-smoke system of the boiler and the establishment of water supply flow rate of the boiler are kept synchronous, the water supply amount of a feed pump is reduced after a separator meets water in the water supply process of the boiler, the water supply flow rate is established by utilizing BCP circulation, and the emission of a WDC valve is reduced. The running time of the air-smoke system before ignition is shortened as much as possible, the low air volume is adopted for purging after the air-smoke system is started, the total air volume is not lower than 30%, and the ignition is immediately carried out after the purging of the hearth is finished. The time from the furnace purging to the boiler ignition can not exceed 20min in principle, the bypass and the drain valve of the main reheating steam pipeline are kept closed before the boiler is ignited, the main steam pressure is increased after the boiler is ignited, and the high bypass and the low bypass are manually opened by 10%. According to the pressure increasing speed of the main steam pressure, the high side and the low side are slowly opened, the constant pressure mode can be put into when the high side is opened to 23 percent, the automatic injection is carried out when the low side is opened to 30 percent, the fuel quantity is increased as soon as possible after ignition, the temperature rising rate of the shield-over, high-over and high-reentry/exit is controlled to be 2 ℃/min, the metal temperature of a heating surface is prevented from being reduced, the temperature rising rate of the main steam is controlled to be not more than 0.875 ℃/min in a temperature state, the pressure rising rate of the main steam is not more than 0.067MPa/min (the initial temperature and pressure are 340 ℃ and 3MPa), the temperature rising rate of the main steam is controlled to be not more than 0.667 ℃/min in a thermal state, and the pressure rising rate of the main steam is not more than 0.042MPa/min (the initial temperature and pressure are 510 ℃ and 9.5 MPa).

4. Before the unit is connected to the grid, desuperheating water is not used as far as possible, when the main steam temperature is too high to exceed the impulse parameters and the like, and the superheater desuperheating water must be started, the desuperheating water gate is operated to be gradually opened in a pulse mode, the temperature drop rate after desuperheating is controlled not to exceed 2 ℃/min in principle, and the temperature after desuperheating is higher than the corresponding saturation temperature by more than 20 ℃, for example, the first-stage desuperheating water or the second-stage desuperheating water after the steam turbine impulse is started, the above mode is also adopted, and the temperature after desuperheating is prevented from suddenly dropping;

5. when the unit is started in a warm and hot state, the temperatures of the pipe walls of the partition screen superheater, the high-temperature superheater and the high-temperature reheater are comprehensively checked after the bypass is opened. (focus is on investigating the wall temperature on the same screen of the end of the header on the low point);

6. in the starting process of the unit, when the temperature of each pipe wall of the separating screen superheater, the high-temperature superheater and the high-temperature reheater is raised to 350-plus-400 ℃, the wall temperature needs to be stabilized for 1 hour, and then the heat load of the boiler is continuously increased.

7. During the process of impulse transfer and grid connection and after grid connection, the boiler should keep the parameters relatively stable. When increasing the fuel amount, attention should be paid to the stable change of the steam temperature and the smoke temperature.

8. After the unit normally washes and turns, the temperatures of the pipe walls of the partition screen superheater, the high-temperature superheater and the high-temperature reheater are comprehensively checked, and the comprehensive check is realized through an alarm mechanism (the point that the temperature of the pipe wall at the end part of the header is higher than that of the same screen wall is mainly checked);

9. when the unit operates in a wet state, a specially-assigned person is required to monitor and adjust the water level of the steam-water separator, so that the phenomenon that the temperature of the reheater and the steam-water separator is suddenly reduced due to the fact that the steam-water separator is full of water is prevented;

10. during the dry state of the boiler, feed water and fuel are added properly, the superheat degree of an outlet of a steam-water separator of the boiler is controlled to be below 10 ℃, the phenomenon of overtemperature of a water wall is prevented, and simultaneously, the load is increased as early as possible and does not stay in the load range;

11. after the CCS mode is put into, the load change rate of the unit is set to be 3MW/min, the load is increased in stages, the stable operation is carried out for 30 minutes when the load is increased by 50MW, the load change rate is controlled according to normal values after the load is increased to be more than 800MW and the operation parameters of the unit and the metal wall temperature are checked to be abnormal.

12. Strictly monitoring the metal wall temperature and deviation condition of each heating surface in the starting process of the unit, controlling the temperature of each metal pipe wall not to exceed the limit, suspending temperature rise and pressure rise when the wall temperature of any point exceeds the limit or abnormally rises, and continuing to rise and pressure after the temperature is regulated stably and normally;

13. and after grid connection and unit load increase to 500MW, respectively carrying out condensed water sampling, testing the Fe concentration, and if the Fe concentration is kept unchanged, executing the load-adding requirement. If the concentration of Fe is increased, the load is strictly prohibited to be increased, and the condensed water sampling test comparison is carried out every two hours, and when the concentration of Fe is reduced, the load can be increased according to the requirement.

Normal operation of machine set

1. The monitoring and adjustment of the thermal deviation of each heating surface are enhanced during the operation, the deviation of the left side and the right side of the steam temperature of the superheater outlet in the operation of the boiler is enabled to be not more than 5 ℃, the deviation of the left side and the right side of the steam temperature of the screen superheater outlet is not more than 10 ℃, and the deviation of the left side and the right side of the steam temperature of the reheater outlet is not more than 10 ℃;

2. during the operation of the boiler, disturbance is generated on a steam system when load adjustment, starting and stopping of a coal pulverizing system, furnace or flue soot blowing and other operations are carried out and coal quality changes, and under the conditions, special attention needs to be paid to monitoring of steam temperature and wall temperature and adjustment of coal-water ratio;

3. in normal operation, the primary, secondary and tertiary desuperheating water of the superheater and a flue gas baffle of a reheater are automatically controlled by INFIT, and the accident desuperheating water of the reheater is in a good standby state. When the desuperheater of the superheater and the reheater is manually adjusted, attention is paid to monitoring the temperature change of the medium before and after the desuperheater, attention is paid not to sudden increase and sudden decrease, and the steam temperature is stably adjusted according to the deviation of the steam temperature and the temperature change situation after the desuperheater. The falling of oxide skin caused by large sudden temperature rise and sudden temperature drop after the temperature reducer is prevented. When the temperature of the reheated steam is adjusted, the smoke baffle is not required to be opened or closed suddenly. In the process of using the desuperheating water, the sufficient superheat degree of steam after the desuperheating water is ensured;

4. and controlling the load change rate to be not more than 15MW/min when the load is normally increased and decreased in the operation of the unit. Note that the temperature of the main steam is monitored to be not more than 595 ℃, the temperature of the reheated steam is not more than 608 ℃, and the temperature of the steam at the outlet of the platen superheater is not more than 550 ℃;

5. ensuring 100% operation of condensate fine treatment equipment, ensuring that the conductivity of water and hydrogen supplied to a unit is less than 0.1 mu S/cm, and controlling the concentration of dissolved oxygen in water to be 30-150 mu g/L by supplying water and adding oxygen;

6. the method comprises the steps of performing metal temperature inspection on a heating surface of a boiler in the operation process, performing contact processing in time when a fault of a metal temperature measuring point on the heating surface is found, inspecting the wall temperature condition of the metal heating surface every time, and realizing the purpose through an alarm mechanism, wherein the condition that the temperature of individual tube panels of a wall temperature superheater and a reheater is abnormally increased or is higher than that of peripheral tube panels for a long time is found, analyzing and reporting specialties in time, controlling the temperature of the tube walls not to exceed the limit, reducing the load and the main reheating steam temperature operation if necessary, and avoiding overheating and tube explosion of the superheater and the reheater caused by the falling of oxide skin.

Unit shutdown

1. The normal shutdown of the unit does not adopt a sliding shutdown mode, under special conditions, a sliding parameter shutdown mode can be adopted only by the consent of a department, the target value of the main steam temperature of the sliding parameter shutdown is controlled at 500 ℃ at the lowest, the reheated steam temperature is 480 ℃, and the water inlet of a superheater in a low-load area and the peeling of oxide skin caused by sudden change of the steam temperature of an inlet and an outlet of each heating surface are prevented;

2. when the empty coal bunker needs to be moved in the boiler blowing-out process, the steam temperature is easy to greatly fluctuate due to fuel quantity fluctuation at the low-load stage in the later period of the stopping, the coal bunker coal level is particularly noticed when the boiler is stopped, and the time from stopping to moving the empty coal feeder and the coal pulverizer is controlled not to exceed 10 min;

3. the temperature drop rate of the steam temperature of the control screen passing an inlet and an outlet, passing the inlet and the outlet and the high reentry and the outlet is not more than 1 ℃/min and the main steam pressure drop rate is not more than 0.08MPa/min in the normal shutdown and slip shutdown processes of the unit;

4. when the load of the unit is lower than 500MW in the shutdown process, the load change rate is controlled according to 3MW/min, and the unit stably operates for at least 30min near three load sections of 500MW, 400MW and 350 MW;

5. in the shutdown process, the total coal amount is controlled to be below 100t/h before the steam turbine is opened, the BID is below 250MW, the high bypass opening degree is reduced, and the steam impact caused by the quick opening and closing of the bypass when the steam turbine is opened is reduced;

6. when the boiler is normally shut down or is suddenly shut down in case of failure, the boiler is shut down and is ventilated and purged for 10 minutes by keeping 1300t/h air volume, the conveying and induced draft fan is stopped, the primary air outlet door of the air preheater, the inlet and outlet doors of the denitration reactor, the bypass door of the denitration reactor, the high and low pressure bypass valves, the water feeding main door of the boiler and the water discharging main doors of the steam-water system are closed. In order to prevent sudden temperature drop, the oil gun is prohibited from being reserved for leakage detection. Before the boiler discharges water, the natural ventilation work of the boiler is not carried out;

7. the pressure of the steam-water separator is reduced to 1.0MPa, and the water on the water-cooled wall of the boiler and the pressure of the economizer are discharged while the boiler is kept in a furnace-closed state. When the pressure of the steam-water separator is reduced to 0.5MPa, the exhaust air doors of the economizer, the water-cooled wall, the superheater and the reheater are opened to remove water vapor in the system. After the water cooling wall of the boiler and the water discharging of the economizer are checked and water is discharged for 2 hours, the air discharging doors and the water discharging doors of the steam-water system are closed;

8. after the furnace is sealed for 36 hours and the water is discharged from the boiler, if a wind and smoke system channel is established as required for maintenance, a movable blade of a blower and a static blade of an induced draft fan are opened at the opening degree of 10-20-30-40-60-80-100% every 30 minutes, and the boiler is naturally ventilated and cooled;

9. if forced ventilation cooling in the furnace is required due to maintenance requirements, after natural ventilation is carried out for 12 hours, forced ventilation is carried out to open a movable blade of a blower, a draught fan is started to operate, the opening of a flue gas temperature regulation baffle is adjusted to balance the temperature drop of flue gas in a tail flue, the negative pressure of a hearth is adjusted to control the temperature drop rate of the flue gas at the outlet of the hearth to be about 1 ℃/min, the temperature drop rate of walls of a superheater and a reheater is controlled to be not more than 0.5 ℃/min, the water seal of the boiler is not damaged in the initial stage, and the water seal of the boiler can be damaged after the temperature of a water cooling wall is reduced to be below 100 ℃.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A control method for slowing down the generation and the falling of oxide skin in a heating pipe of a power station unit comprises the following steps;

in the step S2, the alarm mechanism comprises a wall body (1) and a temperature reduction pipeline (2) spirally arranged on the outer side wall of the wall body (1), the temperature reduction work on the wall body (1) is realized through the temperature reduction pipeline (2), a communicating pipeline (4) is arranged on the outer side wall of the temperature reduction pipeline (2), a water regulating valve (5) is arranged on the side wall of the communicating pipeline (4), and a regulating component for regulating the flow of water flow is fixedly arranged at the lower end of the water regulating valve (5);

the adjusting assembly comprises a driven meshing gear (602) fixedly arranged in the alarm assembly (3) and an adjusting rod (6) rotatably arranged at the upper end of the alarm assembly (3), the upper end of the adjusting rod (6) is fixedly arranged with a rotating valve rod for adjusting the flow of the water valve (5), the lower end of the adjusting rod (6) is fixedly provided with an adjusting bar gear (601), and the lower end of the adjusting bar gear (601) is meshed with the driven meshing gear (602);

the side wall of the wall body (1) is provided with an alarm component (3) in a nested mode, the alarm component (3) is fixedly connected with a regulating component, the alarm component (3) is matched with the regulating component for use, temperature measurement of the interior of the wall body (1) is achieved, and regulation of the size of water flow is achieved, an alarm contact element (8) is arranged in the alarm component (3), and when an internal mechanism of the alarm component (3) runs, starting and early warning of the alarm contact element (8) can be controlled;

the alarm component (3) comprises a temperature measuring cavity (301) which is arranged on a wall body (1) in a nested mode and a heat insulation outer wall (303) which is fixedly arranged on the temperature measuring cavity (301), a temperature measuring pipe (302) is arranged inside the heat insulation outer wall (303), a pushing sliding plug (304) is arranged in the heat insulation outer wall (303) in a sealing and sliding mode, a measuring component (307) used for measuring is arranged on the side wall of the pushing sliding plug (304), scales (7) are arranged on the side wall of the measuring component (307), a sliding piston (306) used for pushing a driven meshing gear (602) to move is fixedly arranged in the heat insulation outer wall (303), and the pushing sliding plug (304) and the sliding piston (306) are directly connected through a first spring (305);

2. The control method for slowing down the formation and the falling of the oxide skin in the heating pipe of the power station unit as claimed in claim 1, wherein in the step S1, a water source is firstly added into the boiler, and the water source has the quality standard of pH value 9.2-9.6, Fe content less than or equal to 50 μ g/L, SiO2 content less than or equal to 30 μ g/L and electric conductivity less than or equal to 0.65 μ S/cm.

3. The control method for slowing down the generation and the falling of the oxide skin in the heating pipe of the power station unit according to claim 2, characterized in that the outside of the water regulating valve (5) is connected with a water pump, so that a circulating temperature reducing water source is conveyed to the communicating pipeline (4) and the temperature reducing pipeline (2).

4. The control method for slowing down the generation and the falling of the oxide skin in the heating pipe of the power station unit according to claim 3, characterized in that the alarm contact element (8) is electrically connected with an external buzzer alarm, and the alarm contact element (8) is triggered by pushing the sliding plug (304) to move, so that the buzzer alarm starts to alarm.

5. The control method for slowing down the generation and the falling of the oxide skin in the heated pipe of the power station unit as claimed in claim 4, characterized in that the temperature measuring cavity (301) is arranged in a spherical shape, and the temperature measuring cavity (301) is filled with easily expandable gas, so that the accurate sensing of the temperature inside the wall body (1) is realized, and the effective measurement of the temperature inside the wall body (1) is realized.