Real-time monitoring and cleaning system and method for coking condition of water-cooled wall area of boiler

Abstract

The invention relates to a coal-fired boiler water-cooled wall area coking condition real-time monitoring and cleaning device which is characterized by comprising a monitoring system, a controller and a cleaning system, and the monitoring system is used for collecting the wall temperature of a boiler water-cooled wall and the smoke temperature in a hearth in real time; the controller is in communication connection with the monitoring system and is used for calculating a heat transfer coefficient based on the wall temperature and the smoke temperature and judging the coking condition of the water-cooled wall area according to the heat transfer coefficient; the cleaning system is in communication connection with the controller and is used for responding to an instruction of the controller to execute cleaning operation; the cleaning operation comprises the steps of adjusting the opening degree of a secondary air adjusting baffle to slow down coking and starting a steam soot blowing system to remove the coking, and real-time monitoring and intelligent cleaning of the coking of the water cooling wall of the coal-fired boiler are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of boiler water cooling wall area coking real-time monitoring cleaning system and method, belong to boiler technical field. BACKGROUND

[0002] With the fluctuation of coal price in recent years, the installed capacity of new energy continues to rise, and the annual utilization hours of thermal power plants are squeezed, showing a year-on-year decline. Thermal power plants are on the brink of loss for a long time. To reduce power generation costs and improve the competitiveness of the unit, most coal-fired units have deviated from the design of the coal used, mainly using lean coal and lignite. However, the economic coal mixed with off-design coal will cause a series of problems, such as boiler heating surface contamination, large-area coking, which reduces the efficiency of the boiler, and causes boiler fire-out abnormal events due to serious coking collapse. At the same time, the combustion system cannot adapt to the change of complex coal, the combustion condition deviates from the original design, and the uneven combustion in the furnace, the flame center skew, the flame wall combustion and other conditions occur, which further causes the local over-temperature of the water cooling wall and the pipe explosion. SUMMARY

[0003] In order to solve the above problems existing in the prior art, the present application provides a kind of boiler water cooling wall area coking real-time monitoring cleaning system and method, realizes the real-time monitoring and intelligent cleaning of coal-fired boiler water cooling wall coking.

[0004] The technical scheme of the present application is as follows:

[0005] A coal-fired boiler water cooling wall area coking real-time monitoring and cleaning device, characterized by: comprising a monitoring system, a controller and a cleaning system, the monitoring system is used for real-time acquisition of the wall temperature of the boiler water cooling wall and the flue gas temperature in the furnace; the controller is in communication connection with the monitoring system, is used for calculating the heat transfer coefficient based on the wall temperature and the flue gas temperature, and judging the coking condition of the water cooling wall area according to the heat transfer coefficient; the cleaning system is in communication connection with the controller, and is used for executing cleaning operation in response to the instruction of the controller; the cleaning operation includes adjusting the opening degree of the secondary air damper to slow down coking and starting the steam soot blowing system to remove coking.

[0006] Among them, the controller calculates the logarithmic mean temperature difference based on the water cooling wall inlet wall temperature T ω1 , the water cooling wall outlet wall temperature T ω2 , the flue gas inlet temperature T g1 and the flue gas outlet temperature T g2 . According to the boiler thermal power P and the water cooling wall heat load ratio η, the heat transfer amount Q = ηP is determined; based on the water cooling wall pipe outer diameter d, length L and the number of pipes n, the heat transfer area A = πdLn is determined; the method for calculating the heat transfer coefficient of the controller is based on the heat transfer formula:

[0007] wherein, when k is lower than a preset threshold, it is determined that there is coking in the water cooling wall; the cleaning system responds to the instruction of the controller to perform at least one of the following operations: adjusting the opening degree of the secondary air damper corresponding to the water cooling wall area; starting the steam soot-blowing gun group to perform directional soot blowing.

[0008] wherein, the preset threshold is 1500W / m 2 · K, when k < 1000W / m 2 · K, the opening degree of the secondary air damper and the steam soot-blowing system are synchronously executed.

[0009] wherein, further comprising a temperature data collector and a data processor for processing the signals of the monitoring system and transmitting to the controller.

[0010] wherein, the monitoring system comprises wall temperature measuring points arranged in the water cooling wall area and infrared flue gas temperature measuring guns arranged in the boiler furnace.

[0011] wherein, the cleaning system comprises a full-stroke adjustable secondary air damper arranged in layers corresponding to the burners and a plurality of steam soot-blowing gun groups evenly distributed in the left and right walls of the boiler and the peripheral area of the burners.

[0012] A real-time monitoring and cleaning method for coking in the water cooling wall area of a coal-fired boiler, characterized in that it comprises the following steps: real-time monitoring of the wall temperature of the boiler water cooling wall and the flue gas temperature in the furnace;

[0013] calculating the heat transfer coefficient k based on the wall temperature and the flue gas temperature;

[0014] judging the coking condition of the water cooling wall area according to the heat transfer coefficient;

[0015] in response to the coking condition exceeding the threshold, performing a cleaning operation;

[0016] wherein, the cleaning operation comprises adjusting the opening degree of the secondary air damper and starting the steam soot-blowing system.

[0017] The present application has the following beneficial effects:

[0018] The present application realizes real-time monitoring and intelligent cleaning of coking in the water cooling wall of the coal-fired boiler through the cooperative relationship of the monitoring system, the controller and the cleaning system, significantly improves the operation efficiency and safety of the boiler, reduces the heat transfer efficiency loss caused by coking, improves the thermal efficiency of the boiler, prevents water cooling wall pipe explosion and unplanned shutdown, and reduces equipment maintenance cost; through the hierarchical response mechanism, the combustion condition is optimized, and the service life of the boiler is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present application.

[0020] The reference signs in the figures represent:

[0021] 1, steam blowing gun group; 2, wall temperature measuring point; 3, secondary air adjusting damper; 4, temperature data collector; 5, data processor. DETAILED DESCRIPTION

[0022] The application will be described in detail below in conjunction with the drawings and specific examples.

[0023] Please refer to Figure 1 , the application provides a technical solution:

[0024] A real-time monitoring and cleaning device for coking in the water wall area of a coal-fired boiler, characterized in that it comprises a monitoring system, a controller and a cleaning system. The monitoring system is used to collect the wall temperature of the boiler water wall and the flue gas temperature in the furnace in real time. The monitoring system comprises wall temperature measuring points 2 arranged in the water wall area and an infrared flue gas temperature measuring gun arranged in the boiler furnace. The wall temperature and flue gas temperature are calculated by the wall temperature measuring points 2 and the infrared flue gas temperature measuring gun, and the heat transfer coefficient is calculated. The controller is in communication connection with the monitoring system, and is used to calculate the heat transfer coefficient based on the wall temperature and flue gas temperature, and to judge the coking condition in the water wall area according to the heat transfer coefficient. The cleaning system is in communication connection with the controller, and is used to execute the cleaning operation in response to the instruction of the controller. The cleaning operation includes adjusting the opening of the secondary air adjusting damper 3 to slow down the coking and starting the steam blowing system to remove the coking.

[0025] The device is suitable for supercritical opposed firing boilers. The monitoring system achieves full furnace coverage through distributed arrangement. The wall temperature measuring points 2 adopt thermocouple sensors, which are uniformly installed at the inlet and outlet positions of the water wall tube panel, and collect wall temperature data in real time at a frequency of 1 Hz. The infrared flue gas temperature measuring gun is a rotatable probe, which is installed at the furnace observation hole and scans the flue gas temperature distribution of the furnace every 5 minutes. The controller is a PLC module, which is connected with the monitoring system through the Mo dbus protocol and executes the coking judgment algorithm after receiving the temperature signal. The cleaning system includes an intelligent actuator. The secondary air adjusting damper 3 is an electric regulating valve, which corresponds to the burner in layers. The steam blowing gun group 1 adopts a telescopic design, and the steam flow is controlled by a solenoid valve. When the system is started, the temperature data collector 4 converts the analog signal into digital quantity, and the data processor 5 performs filtering and calibration to ensure that the data error input into the controller is small.

[0026] Specifically, the controller calculates the logarithmic mean temperature difference based on the water wall inlet wall temperature T ω1 , the water wall outlet wall temperature T ω2 , the flue gas inlet temperature T g1 and the flue gas outlet temperature T g2 . According to the boiler thermal power P and the water wall heat load ratio η, the heat transfer amount Q = ηP is determined; based on the outer diameter d, length L and the number of pipes n of the water wall pipe, the heat transfer area A = πdLn is determined; the method for calculating the heat transfer coefficient of the controller is based on the heat transfer formula:

[0027] When k is lower than the preset threshold value, it is determined that the water wall is coking; the cleaning system responds to the instruction of the controller and performs at least one of the following operations: adjusting the opening degree of the secondary air damper 3 corresponding to the water wall area; starting the steam soot blowing gun group 1 of the steam soot blowing system to perform directional soot blowing; the preset threshold value is 1500W / m 2 ·K, the secondary air damper 3 opening degree and the steam soot blowing system are synchronously executed when k < 1000W / m 2 ·K.

[0028] Further, the preset threshold value is divided into two levels: the early warning threshold value is 1500W / m 2 ·K, and the forced cleaning threshold value is 1000W / m 2 ·K. The controller compares the real-time k value with the threshold value: if 1500≤k<1800W / m 2 ·K, it is determined that there is slight coking; if 1000≤k<1500W / m 2 ·K, it is determined that there is moderate coking; and if k < 1000W / m 2 ·K, it is determined that there is severe coking.

[0029] Specifically, when there is slight coking, the controller instructs the secondary air damper 3 to increase the opening degree by 10-20%, for example, from 50% to 70%, to enhance the air volume in this area to peel off loose ash; when there is moderate coking, the steam soot blowing gun group 1 is started to perform directional soot blowing: the controller locates the coking area and the corresponding steam soot blowing gun group 1 is swept; when there is severe coking, the following is synchronously executed: first, the damper opening degree is adjusted to the maximum, and at the same time, the steam soot blowing gun group 1 is continuously swept.

[0030] After cleaning, the controller monitors the rising trend of the k value; if it does not recover to 1500W / m 2 ·K or above within a certain time, the cleaning is repeated or a shutdown suggestion is issued.

[0031] It also includes a temperature data collector 4 and a data processor 5 for processing the signals of the monitoring system and transmitting them to the controller.

[0032] The cleaning system includes fully adjustable secondary air dampers 3 arranged in layers corresponding to the burners and a plurality of steam soot blowing gun groups 1 evenly distributed in the left and right walls of the boiler and the peripheral area of the burners; four secondary air dampers 3 are arranged corresponding to each layer of burners. The controller adjusts the opening degree through the PID algorithm: according to the coking position, for example, when the right side is coking, the opening degree of the right side secondary air damper 3 is increased and the opening degree of the left side is reduced to balance the combustion.

[0033] A real-time monitoring and cleaning method for coking in a water-cooled wall area of a coal-fired boiler, characterized by the following steps: real-time monitoring of the wall temperature of the boiler water-cooled wall and the flue gas temperature in the furnace;

[0034] Calculating the heat transfer coefficient k based on the wall temperature and the flue gas temperature;

[0035] Determining the coking condition of the water-cooled wall area according to the heat transfer coefficient;

[0036] In response to determining that the coking condition exceeds a threshold value, performing a cleaning operation;

[0037] The cleaning operation includes adjusting the opening of the secondary air damper 3 and starting the steam blowing system.

[0038] The above is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, as described in the specification and drawings of the present application, are also included in the patent protection scope of the present application.

Claims

1. A real-time monitoring and cleaning system for coking in the boiler water wall area, characterized by: It includes a monitoring system, a controller and a cleaning system. The monitoring system is used to collect the wall temperature of the boiler water-cooled wall and the flue gas temperature in the furnace in real time; the controller is communicated with the monitoring system and is used to calculate the heat transfer coefficient based on the wall temperature and the flue gas temperature, and judge the coking condition of the water-cooled wall area according to the heat transfer coefficient; the cleaning system is communicated with the controller and is used to respond to the instructions of the controller to perform cleaning operations; the cleaning operations include adjusting the opening of the secondary air damper to slow down coking and starting the steam soot blowing system to remove coking.

2. A real-time monitoring and cleaning system for coking in a boiler water wall area according to claim 1, characterized in that: The controller is based on the water wall inlet temperature T ω1 , water wall outlet temperature T ω2 , Flue gas inlet temperature T g1 and flue gas outlet temperature T g2 , calculate the logarithmic mean temperature difference: The heat transfer amount Q = ηP is determined based on the boiler thermal power P and the water wall heat load ratio η. The heat transfer area A = πdLn is determined based on the water wall tube outer diameter d, length L, and number of tubes n. The controller calculates the heat transfer coefficient based on the heat transfer formula:

3. A real-time monitoring and cleaning system for coking in a boiler water wall area according to claim 2, characterized in that: When k is lower than a preset threshold, it is determined that coking exists on the water-cooled wall; the cleaning system responds to the instruction of the controller and performs at least one of the following operations: adjusting the opening of the secondary air damper corresponding to the water-cooled wall area; starting the steam soot blowing gun group for directional soot blowing.

4. A real-time monitoring and cleaning system for coking in a boiler water wall area according to claim 3, characterized in that: The preset threshold is 1500W / m 2 K, when k<1000W / m 2 At K, the secondary air damper opening and steam soot blowing system are synchronously executed.

5. The real-time monitoring and cleaning system for coking in the boiler water wall area according to claim 1, characterized in that: It also includes a temperature data collector and a data processor, which are used to process the signals of the monitoring system and transmit them to the controller.

6. The real-time monitoring and cleaning system for coking in the boiler water wall area according to claim 1, characterized in that: The monitoring system includes wall temperature measuring points arranged in the water-cooled wall area and an infrared smoke temperature measuring gun set in the boiler furnace.

7. The real-time monitoring and cleaning system for coking in the boiler water wall area according to claim 1, characterized in that: The cleaning system includes fully adjustable secondary air dampers arranged in layers corresponding to the burners and multi-layer steam soot blowing gun groups evenly distributed on the left and right walls of the boiler and the surrounding areas of the burners.

8. A method for real-time monitoring and cleaning of coking in the water wall area of ​​a boiler, characterized in that: The following steps are involved: Real-time monitoring of the boiler water wall temperature and the flue gas temperature in the furnace; Calculating the heat transfer coefficient k based on the wall temperature and smoke temperature; Determining the coking condition of the water wall area based on the heat transfer coefficient; In response to determining that the coking condition exceeds a threshold, performing a cleaning operation; The cleaning operation includes adjusting the opening of the secondary air damper and starting the steam soot blowing system.

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