Air leakage treatment system and method for dry slag removal boiler bottom of pulverized coal fired boiler of power station

Abstract

The invention discloses a power station pulverized coal boiler dry deslagging furnace bottom air leakage treatment system and method, relates to the technical field of power station boiler dry deslagging, and mainly aims to reduce inorganized cold air entering a hearth, reduce adverse effects on the hearth temperature, enable the combustion process to be more stable and improve the combustion efficiency. According to the main technical scheme, the dry slag removal furnace bottom air leakage treatment system for the pulverized coal fired boiler of the power station comprises a dry bottom hopper, a slag removal box body and an air suction and exhaust device, a dry slag conveying belt is arranged in the slag removal box body, and a slag falling opening is formed in the position, opposite to the dry bottom hopper, of the slag removal box body; exhaust ports are formed in the two sides, in the length direction of the dry slag conveying belt, of the slag falling port respectively, the exhaust ports are communicated with the air suction and exhaust device through a communication air duct, a switching valve is arranged on the communication air duct, and the opening degree of the switching valve is adjustable.

Description

Technical Field

[0001] The invention belongs to the technical field of dry slagging of power station boilers, and in particular relates to a system and method for controlling air leakage from the bottom of a dry slagging furnace of a pulverized coal boiler in a power station. Background Art

[0002] In recent years, the boiler dry slag discharge system has been widely used. In this system, in order to ensure that the large slag will not coke and overheat after entering the slag bin after cooling, the large slag falling into the cold ash hopper must be fully cooled. However, the cooled wind will be converted into hot air and enter the furnace directly from the bottom of the furnace. For the furnace, this part of the wind is unorganized cold wind. Once entering the furnace, it will lower the furnace temperature, move the flame center upward, and then cause the flue gas temperature at the furnace outlet to increase. Under high load conditions, if there is a large amount of air leakage in the furnace, the superheater will face the risk of overheating; under low load conditions, a large amount of air leakage in the furnace may cause unstable combustion, increase in incomplete combustion losses, and even fire extinguishing. In addition, a large increase in the amount of air leakage at the bottom of the furnace will increase the oxygen content in the main combustion zone, thereby increasing the NOx concentration at the furnace outlet. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a system and method for controlling bottom air leakage in a dry slag removal furnace of a pulverized coal boiler in a power station, the main purpose of which is to reduce the entry of unorganized cold air into the furnace, reduce the adverse effects on the furnace temperature, make the combustion process more stable, and improve combustion efficiency.

[0004] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0005] A first aspect of an embodiment of the present invention provides a system for controlling air leakage from the bottom of a dry slag removal furnace of a pulverized coal boiler in a power station, comprising a cold ash hopper, a slag discharge box and an exhaust and suction device, wherein a dry slag conveyor belt is arranged in the slag discharge box, and a slag drop port is arranged on the slag discharge box at a position relative to the cold ash hopper, exhaust ports are respectively arranged on both sides of the slag drop port along the length direction of the dry slag conveyor belt, the exhaust ports are connected to the exhaust and suction device through a connecting air duct, a switch valve is arranged on the connecting air duct, and the opening of the switch valve is adjustable.

[0006] Optionally, the power station pulverized coal boiler dry slagging furnace bottom air leakage control system further includes a nitrogen oxide sensor, and the nitrogen oxide sensor is arranged at the furnace outlet.

[0007] Optionally, the power station pulverized coal boiler dry slag removal furnace bottom air leakage control system further includes at least two temperature sensors, and the at least two temperature sensors are respectively arranged on the dry slag conveyor belt and the slag discharge box.

[0008] Optionally, the power station pulverized coal boiler dry slag removal furnace bottom air leakage control system also includes a control device, which is electrically connected to the switch valve, the nitrogen oxide sensor and at least two of the temperature sensors, respectively, and the control device is used to receive information transmitted by the nitrogen oxide sensor and at least two of the temperature sensors, and control the switch valve according to the received information.

[0009] Optionally, the outlet of the air intake and exhaust device is connected to the secondary air supply pipe of the boiler.

[0010] Optionally, a dust collector is also provided on the communication air duct, and the dust collector is located on the downstream side of the switch valve along the flow direction.

[0011] Optionally, the power station pulverized coal boiler dry slagging furnace bottom air leakage control system also includes a slag dropping pipe, one end of the slag dropping pipe is connected to the dust discharge port of the dust collector, and the other end is connected to the slag discharge box, and an air lock is provided on the slag dropping pipe.

[0012] Optionally, at least two air locks are provided, and at least two of the air locks are connected in series.

[0013] A second aspect of the embodiments of the present invention provides a method for treating air leakage from the bottom of a pulverized coal boiler in a power station using a system for treating air leakage from the bottom of a pulverized coal boiler in a power station using dry slagging. The method comprises:

[0014] Obtaining nitrogen oxide concentration data at the furnace outlet;

[0015] Acquiring temperature data of the dry slag conveyor belt;

[0016] Acquiring temperature data of the slag discharge box;

[0017] The nitrogen oxide concentration data is compared with a first pre-stored threshold, the temperature data of the dry slag conveyor belt is compared with a second pre-stored threshold, and the temperature data of the slag discharge box is compared with a third pre-stored threshold in real time, and the opening of the switch valve is adjusted based on the comparison result.

[0018] Optionally, during the operation of the power plant pulverized coal boiler dry deslagging furnace bottom air leakage control system, when the nitrogen oxide concentration data exceeds the first pre-stored threshold value by 5 mg / Nm 3 when the temperature data of the dry slag conveyor belt exceeds the second pre-stored threshold value by 5°C, the opening of the switch valve is reduced by 10%; when the temperature data of the slag discharge box exceeds the third pre-stored threshold value by 1°C, the opening of the switch valve is reduced by 3%.

[0019] By means of the above technical solution, the present invention has at least the following beneficial effects:

[0020] The embodiment of the present invention provides a system and method for treating air leakage at the bottom of a dry slag removal furnace of a pulverized coal boiler in a power station. By arranging exhaust ports on both sides of the slag drop port and connecting the exhaust ports to the air intake and exhaust device through a connecting air duct, the air pressure inside the slag removal box can be adjusted to ensure that the inside of the slag removal box is always kept within a suitable air pressure range, thereby effectively preventing air leakage at the bottom of the furnace caused by unstable pressure. A large amount of "unorganized" air leakage is prevented from entering the furnace, absorbing the radiant heat of the furnace to cause the furnace temperature to drop, and directly disrupting the "orderly" air distribution of combustion, thereby avoiding problems such as deviation of the furnace flame center, overheating of the superheater and reheater, increase in cooling water volume, increase in exhaust gas temperature, and reduction in unit operation economy. At the same time, it can reduce the situation where the oxygen content in the main combustion zone increases due to a large increase in the amount of air leakage at the bottom of the furnace, thereby effectively solving the problem of increased NOx concentration at the furnace outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a system for treating air leakage from the bottom of a pulverized coal boiler in a power station using dry slagging according to an optional embodiment of the present invention.

[0022] The reference numerals are:

[0023] 1. Cold ash hopper; 2. Slag discharge box; 3. Suction and exhaust device; 4. Dry slag conveyor belt; 5. Slag drop port; 6. Exhaust port; 7. Communication air duct; 8. Switch valve; 9. Secondary air supply pipe; 10. Dust collector; 11. Slag drop pipe; 12. Air lock. DETAILED DESCRIPTION

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] In recent years, the dry slag discharge system of pulverized coal boilers in power plants has been widely used. The dry slag discharge system of pulverized coal boilers in power plants includes a cold ash hopper 1 and a slag discharge box 2. The cold ash hopper 1 is located at the lower part of the boiler furnace and is used to collect waste residues such as ash and incompletely burned solid particles generated after boiler combustion. These waste residues will fall into the cold ash hopper 1 for temporary storage under the action of gravity. The shape of the cold ash hopper 1 is generally inverted cone or funnel shape, which is conducive to the concentration and discharge of waste residues.

[0029] The slag discharge box 2 is located at the lower part of the cold ash hopper 1, and is connected to the cold ash hopper 1, and is used to receive the waste slag dropped from the cold ash hopper 1, and transport the waste slag to a designated location for subsequent processing. Specifically, a slag drop port 5 is provided on the slag discharge box 2 at a position relative to the cold ash hopper 1, so that the waste slag in the cold ash hopper 1 can smoothly fall into the slag discharge box 2. A dry slag conveyor belt 4 is provided inside the slag discharge box 2, which is used to transport the waste slag dropped from the cold ash hopper 1.

[0030] It should be noted that, in order to ensure that the waste slag no longer cokes and overheats, one end of the slag discharge box 2 is connected to a strong cooling fan (not shown in the attached drawings) through a pipeline. The strong cooling fan delivers cooling air to the inside of the slag discharge box 2 through the pipeline, quickly reduces the temperature of the waste slag, and effectively prevents the waste slag from coking and overheating. Then, when the strong cooling fan delivers cooling air to the inside of the slag discharge box 2 through the pipeline, the air pressure inside the slag discharge box 2 increases, and the cooling air that exchanges heat with the waste slag will enter the cold ash hopper 1 through the slag drop port 5, and enter the furnace through the cold ash hopper 1 to participate in the combustion, which greatly disturbs the combustion in the furnace, seriously affecting the safe and economical operation of the boiler under high or low loads.

[0031] To solve the above problems, see Figure 1As shown, according to the first aspect of the embodiment of the present invention, a system for treating air leakage from the bottom of a dry slag removal furnace of a power station coal-fired boiler is provided. The system for treating air leakage from the bottom of a dry slag removal furnace of a power station coal-fired boiler is provided with an additional air intake and exhaust device 3, and at the same time, air outlets 6 are respectively provided on both sides of a slag drop port 5 along the length direction of a dry slag conveyor belt 4, so that the air outlets 6 are connected to the air intake and exhaust device 3 through a connecting air duct 7, and an on-off valve 8 with adjustable opening is installed on the connecting air duct 7.

[0032] By arranging exhaust ports 6 on both sides of the slag outlet 5 and connecting the exhaust ports 6 with the suction and exhaust device 3 through the connecting air duct 7, the air pressure inside the slag discharge box 2 can be adjusted to ensure that the inside of the slag discharge box 2 is always kept within a suitable air pressure range, thereby effectively preventing air leakage at the bottom of the furnace caused by unstable pressure. Prevent a large amount of "unorganized" air leakage from entering the furnace, prevent it from absorbing the radiant heat of the furnace to cause the furnace temperature to drop, and directly disrupt the "orderly" air distribution of combustion, thereby avoiding problems such as the deviation of the furnace flame center, overheating of the superheater and reheater, increase in cooling water volume, increase in exhaust gas temperature, and reduction in unit operation economy. At the same time, it can reduce the situation where the oxygen content in the main combustion zone increases due to a large increase in the amount of air leakage at the bottom of the furnace, thereby effectively solving the problem of increased NOx concentration at the furnace outlet.

[0033] The exhaust port 6 is adjacent to the slag outlet 5. In actual application, when the air pressure inside the slag discharge box 2 increases due to the cooling air delivered by the strong cooling fan, the gas can be discharged from the exhaust port 6 near the slag outlet 5 at the fastest speed, which greatly improves the exhaust efficiency and ensures that the air pressure near the slag outlet 5 inside the slag discharge box 2 can be effectively adjusted in a short time, avoiding the problem of air leakage at the bottom of the furnace caused by excessive air pressure.

[0034] Among them, exhaust ports 6 are provided on both sides of the slag outlet 5 along the flow direction, and the flow direction is the flow direction of the cooling air inside the slag discharge box 2. In this embodiment, the flow direction is the length direction of the dry slag conveyor belt 4. In practical applications, after the cooling air exchanges heat with the waste slag, the airflow will flow in a specific direction. The exhaust ports 6 are provided on both sides of the slag outlet 5, so that excess gas can be captured and discharged in time at the key position of the airflow. No matter which direction the airflow flows from, it can be ensured that there is a corresponding exhaust port 6 that can respond quickly to control the air pressure near the slag outlet 5 within a reasonable range.

[0035] Specifically, the exhaust port 6 is connected to the exhaust device 3 through the connecting air duct 7, and the exhaust device 3 can be an exhaust fan or the like. When the strong cooling fan delivers cooling air to the slag discharge box 2, causing the internal air pressure of the slag discharge box 2 to increase, the exhaust fan sucks in excess gas from the exhaust port 6 through the connecting air duct 7 to prevent the bottom of the furnace from leaking due to excessive pressure. It is understandable that by timely discharging the cooling air after heat exchange with the waste slag, it can be prevented from entering the cold ash hopper 1 and then entering the furnace to participate in combustion, thereby preventing the furnace temperature from decreasing, the flame center from shifting, the superheater and reheater from overheating, the cooling water volume from increasing, the exhaust gas temperature from increasing, and other problems, thereby ensuring the safe and economical operation of the boiler under high or low load. At the same time, the exhaust fan can also solve the problem of increased NOx concentration at the furnace outlet. It reduces the situation where the amount of oxygen in the main combustion zone increases due to a large increase in the amount of air leakage at the bottom of the furnace, thereby reducing the generation of NOx and helping to meet environmental protection requirements.

[0036] The connecting air duct 7 can be a pipe. For example, the connecting air duct 7 can be a pipe made of various metal materials such as a steel pipe and a stainless steel pipe, which have high strength and stability and can adapt to different pressure and temperature conditions. In addition, the connecting air duct 7 can also be a plastic pipe, such as a high-temperature resistant engineering plastic pipe, which has the characteristics of light weight, low cost, and corrosion resistance. It can also be a fiber composite material pipe, which usually has good insulation performance and corrosion resistance, and can also withstand a certain pressure.

[0037] Specifically, a switch valve 8 is provided on the communication air duct 7, and the opening of the switch valve 8 is adjustable. For example, the light opening valve can be a butterfly valve, a ball valve, a gate valve, a stop valve or a solenoid valve, etc., which is not limited in this embodiment. When the internal air pressure of the slag discharge box 2 is low, the opening of the switch valve 8 can be appropriately reduced to reduce the amount of gas sucked out from the exhaust port 6 by the suction and exhaust device 3 to maintain the inside of the slag discharge box 2 in a relatively stable air pressure range. When the strong cooling fan delivers a large amount of cooling air to the slag discharge box 2, causing the internal air pressure to rise sharply, the opening of the switch valve 8 can be quickly increased, so that the suction and exhaust device 3 can efficiently discharge excess gas and prevent the occurrence of air leakage at the bottom of the furnace. By flexibly adjusting the opening of the switch valve 8, the precise control of the air leakage control system of the dry slag removal furnace bottom of the power plant pulverized coal boiler can be achieved, ensuring that the boiler can operate safely and economically under high load or low load, while effectively reducing the emission of nitrogen oxides to meet environmental protection requirements.

[0038] In some possible embodiments disclosed in the present invention, the dry slagging furnace bottom air leakage control system for a power station pulverized coal boiler also includes a nitrogen oxide sensor, and the nitrogen oxide sensor is arranged at the furnace outlet.

[0039] By setting up a nitrogen oxide sensor, the concentration of nitrogen oxides (NOx) at the furnace outlet can be monitored in real time, the generation of nitrogen oxides during the boiler combustion process can be timely grasped, and accurate data reference can be provided to operators so that they can understand the impact of system operation on nitrogen oxide emissions at any time. It can be understood that the nitrogen oxide sensor can provide real-time feedback on the concentration change of nitrogen oxides at the furnace outlet, providing a basis for adjusting the opening of the switch valve 8.

[0040] The nitrogen oxide sensor may be a chemiluminescent nitrogen oxide sensor, an electrochemical nitrogen oxide sensor, an infrared absorption nitrogen oxide sensor, etc., which is not limited in this embodiment.

[0041] Specifically, in practical applications, when the nitrogen oxide sensor detects that the nitrogen oxide concentration at the furnace outlet exceeds the environmental protection requirements or the preset safety range, the operator can adjust the operating parameters of the power plant pulverized coal boiler dry slag removal furnace bottom air leakage control system in a timely manner based on these data. For example, if the nitrogen oxide concentration is high, the opening of the switch valve 8 can be increased so that more cooling air after heat exchange with the waste slag can be discharged by the suction and exhaust device 3 through the connecting air duct 7, reducing the air pressure inside the slag removal box 2, reducing the amount of air leakage entering the furnace, and thus reducing the generation of nitrogen oxides.

[0042] In some possible embodiments disclosed in the present invention, the power station pulverized coal boiler dry slag removal furnace bottom air leakage control system also includes at least two temperature sensors, and the at least two temperature sensors are respectively arranged on the dry slag conveyor belt 4 and the slag discharge box 2.

[0043] The temperature sensor may be a thermocouple temperature sensor or an infrared temperature sensor, etc., which is not limited in this embodiment.

[0044] Specifically, the temperature sensor provided on the dry slag conveyor belt 4 can accurately monitor the temperature change of the dry slag conveyor belt 4, and the temperature sensor provided on the slag discharge box 2 can accurately monitor the temperature change of the slag discharge box 2. In practical applications, when the temperature of the dry slag conveyor belt 4 and / or the slag discharge box 2 is too high, it may mean that the heat exchange between the cooling air and the waste slag is insufficient, and the heat of the waste slag is transferred to the dry slag conveyor belt 4, resulting in an increase in the overall temperature inside the slag discharge box 2. At this time, the operator can reduce the opening of the switch valve 8, thereby reducing the amount of gas sucked out from the exhaust port 6, increasing the time and opportunity for the cooling air to contact the waste slag, promoting better heat exchange between the cooling air and the waste slag, and improving the cooling effect.

[0045] In some possible embodiments disclosed in the present invention, the power plant pulverized coal boiler dry slag removal furnace bottom air leakage control system also includes a control device, which is electrically connected to the switch valve 8, the nitrogen oxide sensor and at least two temperature sensors, respectively, and the control device is used to receive information transmitted by the nitrogen oxide sensor and at least two temperature sensors, and control the switch valve 8 based on the received information.

[0046] By setting up a control device, the switch valve 8 can be automatically and accurately controlled according to the information transmitted by the nitrogen oxide sensor and the temperature sensor. For example, when the nitrogen oxide sensor detects that the nitrogen oxide concentration at the furnace outlet exceeds the environmental protection requirements or the preset safety range, the control device can quickly increase the opening of the switch valve 8, so that the suction and exhaust device 3 can efficiently discharge excess gas, reduce the internal air pressure of the slag discharge box 2, and reduce the amount of air leakage into the furnace and the emission of nitrogen oxides. When the temperature sensor detects that the temperature of the dry slag conveyor belt 4 or the slag discharge box 2 is too high, the opening of the switch valve 8 can be appropriately reduced to reduce the amount of gas sucked out of the exhaust port 6 by the suction and exhaust device 3, ensuring that the cooling air and the waste slag have sufficient contact time for heat exchange.

[0047] Among them, the control device can be a programmable logic controller (PLC), etc., which can receive information transmitted by the nitrogen oxide sensor and the temperature sensor, and perform logical judgment and calculation processing based on this information to adjust the opening of the switch valve 8. This embodiment does not limit this.

[0048] Specifically, when the power plant pulverized coal boiler dry slag removal furnace bottom air leakage control system includes a control device, the switch valve 8 is a solenoid valve. When the nitrogen oxide sensor detects that the nitrogen oxide concentration at the furnace outlet is abnormally increased, the control device can immediately send a signal to the solenoid valve to quickly increase its opening, so that the suction and exhaust device 3 can more efficiently discharge excess gas, reduce the internal air pressure of the slag discharge box 2, thereby reducing the amount of air leakage into the furnace, and effectively inhibiting the generation of nitrogen oxides. At the same time, the temperature sensor monitors the temperature changes of the dry slag conveyor belt 4 and the slag discharge box 2 in real time. Once the temperature exceeds the normal range, the control device can also immediately send a signal to the solenoid valve to quickly reduce the opening, reduce the amount of gas sucked out from the exhaust port 6, ensure that the waste slag can be fully cooled, avoid heat transfer to the dry slag conveyor belt 4 and the slag discharge box 2, and ensure the stable operation of the system.

[0049] In some possible embodiments disclosed in the present invention, the outlet of the air intake and exhaust device 3 is connected to the secondary air supply pipe 9 of the boiler. Thus, the cooling air after heat exchange with the waste slag can be introduced into the secondary air supply pipe 9 of the boiler and then sent back into the boiler to participate in the combustion process, thereby realizing the recovery and utilization of waste heat and improving the utilization efficiency of energy.

[0050] Specifically, the gas discharged from the suction and exhaust device 3 after heat exchange with the waste slag usually has a certain temperature, which can assist in preheating the secondary air and increase the temperature of the secondary air, thereby reducing the energy consumed by the boiler for heating the secondary air and improving energy utilization efficiency.

[0051] In some possible implementations of the present invention, see Figure 1 As shown, a dust collector 10 is also provided on the communication air duct 7, and the dust collector 10 is located on the downstream side of the switch valve 8 along the flow direction.

[0052] By setting up the dust collector 10, impurities such as dust and waste particles carried in the gas discharged from the slag discharge box 2 can be effectively removed, preventing the gas carrying impurities such as dust and waste particles from entering the exhaust device 3, the secondary air supply pipe 9 or other equipment, causing adverse effects such as wear and blockage on the equipment.

[0053] The dust collector 10 may specifically be a cyclone dust collector 10 , and the cyclone dust collector 10 is located on the downstream side of the switch valve 8 .

[0054] Specifically, in actual application, the gas flowing out from the inside of the slag discharge box 2 will first pass through the switching valve 8 when flowing through the connecting air duct 7, and then reach the dust collector 10, so that the switching valve 8 can more accurately control the air pressure in the connecting air duct 7, while ensuring that the dust collector 10 can effectively remove impurities, thereby improving the operating efficiency and stability of the system.

[0055] In some possible implementations of the present invention, see Figure 1 As shown, the dry slag removal furnace bottom air leakage control system for the power station pulverized coal boiler also includes a slag dropping pipe 11, one end of the slag dropping pipe 11 is connected to the dust discharge port of the dust collector 10, and the other end is connected to the slag discharge box 2, and an air lock 12 is arranged on the slag dropping pipe 11.

[0056] The air lock 12 can effectively prevent cooling air from entering the dust collector 10 from the slag discharge box 2 through the slag dropping pipe 11, thereby preventing dust discharged from the dust collector 10 from flowing back to the dust collector 10 or the communication air duct 7.

[0057] The slag pipe 11 is a channel for transferring the waste slag and dust collected by the dust collector 10 back to the slag discharge box 2. In actual application, the gas coming out of the slag discharge box 2 enters the dust collector 10 through the connecting air duct 7, and the waste slag and dust separated by the dust collector 10 are returned to the slag discharge box 2 through the slag pipe 11, forming a relatively closed circulation system.

[0058] Among them, the air lock 12 is used to control the on-off state of the slag pipe 11. When the dust collector 10 collects a certain amount of waste slag and dust that needs to be discharged, the air lock 12 is opened, so that the waste slag and dust can smoothly pass through the slag pipe 11 and return to the slag discharge box 2 for further processing. At other times, the air lock 12 remains closed to prevent the gas inside the slag discharge box 2 from exchanging with the outside through the slag pipe 11, thereby maintaining the internal air pressure of the system stable and ensuring the normal operation of the dry slag removal furnace bottom air leakage control system of the power plant pulverized coal boiler.

[0059] In the above embodiments, see Figure 1 As shown, at least two air locks 12 are provided, and at least two air locks 12 are connected in series.

[0060] Multiple air locks 12 are connected in series to form multiple sealing defense lines.

[0061] It is understandable that during the operation of the system, factors such as external air pressure changes or equipment vibrations may affect the sealing performance of a single air lock 12, but multiple air locks 12 connected in series can jointly resist these influences and ensure the sealing of the system.

[0062] A second aspect of the embodiments of the present invention provides a method for treating air leakage from the bottom of a pulverized coal boiler in a power station using a dry slagging furnace bottom air leakage treatment system of a pulverized coal boiler in a power station as described above; the method comprises:

[0063] Obtaining nitrogen oxide concentration data at the furnace outlet;

[0064] Acquire temperature data of the dry slag conveyor belt 4;

[0065] Acquire the temperature data of the slag discharge box 2;

[0066] The nitrogen oxide concentration data is compared with the first pre-stored threshold, the temperature data of the dry slag conveyor belt 4 is compared with the second pre-stored threshold, and the temperature data of the slag discharge box 2 is compared with the third pre-stored threshold in real time, and the opening of the switch valve 8 is adjusted based on the comparison result.

[0067] By obtaining the nitrogen oxide concentration data at the furnace outlet, the temperature data of the dry slag conveyor belt 4, and the temperature data of the slag discharge box 2, the operating status of the system can be fully understood from multiple angles. No longer relying solely on a single parameter for judgment, but taking into account multiple key indicators, the regulation of the system is more accurate. At the same time, adjusting the opening of the switch valve 8 according to the real-time comparison results can respond to changes in the system in a timely manner. Whether it is the fluctuation of nitrogen oxide concentration, the increase of the temperature of the dry slag conveyor belt 4, or the abnormal temperature of the slag discharge box 2, the system can be accurately controlled by quickly adjusting the opening of the switch valve 8.

[0068] Among them, in order to obtain the nitrogen oxide concentration data at the furnace outlet, a nitrogen oxide sensor can be installed on the flue at the furnace outlet to ensure that the nitrogen oxide sensor can be exposed to representative flue gas samples.

[0069] Specifically, the nitrogen oxide sensor can be a chemiluminescent nitrogen oxide sensor, an electrochemical nitrogen oxide sensor, or an infrared absorption nitrogen oxide sensor. In practical applications, the nitrogen oxide sensor transmits the measured nitrogen oxide concentration data to the control device via wired or wireless means. The control device can monitor, record and analyze the data in real time to timely grasp the concentration changes of nitrogen oxides.

[0070] To obtain the temperature data of the dry slag conveyor belt 4 , a temperature sensor may be installed on the surface, edge, etc. of the dry slag conveyor belt 4 to accurately measure the temperature of the dry slag conveyor belt 4 .

[0071] Specifically, the temperature sensor for the dry slag conveyor belt 4 can be a thermocouple temperature sensor or an infrared temperature sensor. In practical applications, the temperature sensor transmits the measured temperature data of the dry slag conveyor belt 4 to the control device via wired or wireless means. The control device can monitor, record and analyze the temperature data of the dry slag conveyor belt 4 in real time, so as to timely grasp the temperature change of the dry slag conveyor belt 4.

[0072] To obtain the temperature data of the slag discharge box 2 , temperature sensors may be installed on the outer wall, inner wall, etc. of the slag discharge box 2 to accurately reflect the temperature of the slag discharge box 2 .

[0073] Specifically, the temperature sensor for the slag discharge box 2 can be a thermocouple temperature sensor or an infrared temperature sensor. In practical applications, the temperature sensor transmits the measured temperature data of the slag discharge box 2 to the control device via a wired or wireless method. The control device can monitor, record and analyze the temperature data of the slag discharge box 2 in real time, so as to grasp the temperature change of the slag discharge box 2 in time.

[0074] Among them, the control device can pre-store a first pre-stored threshold value of nitrogen oxide concentration determined according to the operating requirements and safety standards of the power plant pulverized coal boiler, a second pre-stored threshold value of the temperature of the dry slag conveyor belt 4, and a third pre-stored threshold value of the temperature of the slag discharge box 2, so that the control device can obtain real-time concentration data of nitrogen oxides, real-time temperature data of the dry slag conveyor belt 4, and real-time temperature data of the slag discharge box 2 and compare them with the pre-stored threshold values, thereby generating a control signal to be transmitted to the switch valve 8.

[0075] Specifically, the first pre-stored threshold value, the second pre-stored threshold value, and the third pre-stored threshold value can be stored in a register, a memory, or a non-volatile memory. After the control device obtains the real-time concentration data of nitrogen oxides, the real-time temperature data of the dry slag conveyor belt 4, and the real-time temperature data of the slag discharge box 2, it can use a numerical comparator, a logic judgment circuit, or a software algorithm to compare with the pre-stored threshold value. Then, according to the judgment result, a corresponding control signal is generated to adjust the opening of the switch valve 8. The control signal can be an analog signal or a digital signal, depending on the type and control method of the switch valve 8.

[0076] It is understandable that in order to ensure the accuracy and stability of the opening of the switch valve 8, a feedback control method can be adopted. A feedback device such as a position sensor or a flow sensor is installed on the switch valve 8 to monitor the valve opening or flow in real time, and transmit the feedback signal to the control device. The control device adjusts the control signal according to the difference between the feedback signal and the set value to achieve closed-loop control of the opening of the switch valve 8.

[0077] In the above embodiment, during the operation of the dry slagging furnace bottom air leakage control system for the pulverized coal boiler in the power station, when the nitrogen oxide concentration data exceeds the first pre-stored threshold value of 5 mg / Nm 3 When the temperature data of the dry slag conveyor belt 4 exceeds the second pre-stored threshold value by 5°C, the opening of the switch valve 8 is reduced by 10%; when the temperature data of the slag discharge box 2 exceeds the third pre-stored threshold value by 1°C, the opening of the switch valve 8 is reduced by 3%.

[0078] By clarifying the specific relationship between the threshold value exceeded and the adjustment ratio of the opening of the switch valve 8, it is possible to achieve accurate control of the opening of the switch valve 8. Different parameter exceeding the threshold value corresponds to different opening adjustment ranges, so that the system can make detailed adjustments according to actual conditions, avoiding the problem of over-adjustment or under-adjustment that may be caused by extensive adjustment.

[0079] Specifically, the first pre-stored threshold, the second pre-stored threshold and the third pre-stored threshold are set to correspond to the nitrogen oxide concentration, the temperature of the dry slag conveyor belt 4 and the temperature of the slag discharge box 2, respectively. These pre-stored thresholds are determined according to the design requirements and safe operation standards of the dry slag removal furnace bottom air leakage control system of the power plant pulverized coal boiler. When the actual monitored nitrogen oxide concentration data exceeds the first pre-stored threshold by 5mg / Nm 3, the corresponding adjustment mechanism will be triggered; similarly, when the temperature data of the dry slag conveyor belt 4 exceeds the second pre-stored threshold by 5°C, and when the temperature data of the slag discharge box 2 exceeds the third pre-stored threshold by 1°C, the corresponding adjustment operation will be triggered respectively. For the concentration of nitrogen oxides, when it exceeds the first pre-stored threshold, the opening of the switch valve 8 is increased by 15%. This is because the increase in the concentration of nitrogen oxides may mean that there are problems such as insufficient combustion or air leakage in the furnace. Increasing the opening of the switch valve 8 can increase the exhaust volume of the suction and exhaust device 3, reduce the internal air pressure of the slag discharge box 2, and reduce the amount of air leakage into the furnace, thereby reducing the generation of nitrogen oxides. When the temperature data of the dry slag conveyor belt 4 exceeds the second pre-stored threshold, the opening of the switch valve 8 is reduced by 10%. This is because the excessively high temperature of the dry slag conveyor belt 4 may mean that the heat exchange between the cooling air and the waste slag is insufficient, or the cooling air flow is too large, causing the waste slag to cool too quickly, and the heat is transferred to the dry slag conveyor belt 4. Reducing the opening of the switch valve 8 can reduce the flow of cooling air, prolong the contact time between cooling air and waste slag, improve the cooling effect, and thus reduce the temperature of the dry slag conveyor belt 4. When the temperature data of the slag discharge box 2 exceeds the third pre-stored threshold, the opening of the switch valve 8 is reduced by 3%. The high temperature of the slag discharge box 2 may be caused by waste slag accumulation, insufficient cooling air, or internal structural problems. Reducing the opening of the switch valve 8 can reduce the outflow of cooling air, increase the residence time of cooling air in the slag discharge box 2, improve the cooling effect, and reduce the temperature of the slag discharge box 2.

[0080] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0081] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A system for treating air leakage from the bottom of a pulverized coal boiler in a power station, characterized in that: The invention comprises a cold ash hopper (1), a slag discharge box (2) and an air suction and exhaust device (3); a dry slag conveyor belt (4) is arranged in the slag discharge box (2); a slag drop port (5) is arranged on the slag discharge box (2) at a position relative to the cold ash hopper (1); exhaust ports (6) are respectively arranged on both sides of the slag drop port (5) along the length direction of the dry slag conveyor belt (4); the exhaust ports (6) are connected to the air suction and exhaust device (3) through a connecting air duct (7); a switch valve (8) is arranged on the connecting air duct (7); and the opening degree of the switch valve (8) is adjustable.

2. The power station pulverized coal boiler dry deslagging bottom air leakage control system according to claim 1 is characterized in that: It also includes a nitrogen oxide sensor, which is arranged at the furnace outlet.

3. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 2 is characterized in that: It also comprises at least two temperature sensors, wherein the at least two temperature sensors are respectively arranged on the dry slag conveyor belt (4) and the slag discharge box (2).

4. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 3, characterized in that: The invention also comprises a control device, which is electrically connected to the switch valve (8), the nitrogen oxide sensor and at least two of the temperature sensors respectively, and is used to receive information transmitted by the nitrogen oxide sensor and at least two of the temperature sensors, and control the switch valve (8) according to the received information.

5. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 1, characterized in that: The outlet of the air intake and exhaust device (3) is connected to the secondary air supply pipe (9) of the boiler.

6. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 1, characterized in that: The communication air duct (7) is also provided with a dust collector (10), and the dust collector (10) is located on the downstream side of the switch valve (8) along the flow direction.

7. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 6, characterized in that: It also comprises a slag dropping pipe (11), one end of which is connected to the dust discharge port of the dust collector (10), and the other end of which is connected to the slag discharge box (2), and an air lock (12) is provided on the slag dropping pipe (11).

8. The power station pulverized coal boiler dry deslagging furnace bottom air leakage control system according to claim 7, characterized in that: At least two of the air locks (12) are provided, and at least two of the air locks (12) are connected in series.

9. A method for treating air leakage from the bottom of a dry slagging pulverized coal boiler in a power station, characterized in that: A system for treating air leakage from the bottom of a pulverized coal boiler in a power station by dry slagging is used as described in any one of claims 1 to 8; the method comprises: Obtaining nitrogen oxide concentration data at the furnace outlet; Acquiring temperature data of the dry slag conveyor belt (4); Acquiring temperature data of the slag discharge box (2); The nitrogen oxide concentration data is compared with a first pre-stored threshold value, the temperature data of the dry slag conveyor belt (4) is compared with a second pre-stored threshold value, and the temperature data of the slag discharge box (2) is compared with a third pre-stored threshold value in real time, and the opening of the switch valve (8) is adjusted based on the comparison result.

10. The method for treating air leakage from the bottom of a pulverized coal boiler in a power station according to claim 9, characterized in that: During the operation of the power station pulverized coal boiler dry deslagging furnace bottom air leakage control system, when the nitrogen oxide concentration data exceeds the first pre-stored threshold value by 5 mg / Nm 3 When the temperature data of the dry slag conveyor belt (4) exceeds the second pre-stored threshold value by 5°C, the opening of the switch valve (8) is reduced by 10%; When the temperature data of the slag discharge box (2) exceeds the third pre-stored threshold value by 1°C, the opening of the switch valve (8) is reduced by 3%.

Images