Hazardous waste incineration rotary kiln induced draft system and control method

Abstract

The application discloses a kind of dangerous waste incineration rotary kiln air induction system and control method, including first air induction fan, second air induction fan, air induction fan drive motor, first valve plate, second valve plate, pressure measurement transmission device, controller A, controller B and controller C, the air inlet of first air induction fan and second air induction fan respectively with rotary kiln and two combustion chamber's flue gas discharge pipeline end communication, air induction fan drive motor output shaft and the impeller input shaft of first air induction fan and second air induction fan are fixedly connected, pressure measurement transmission device is set at kiln head of rotary kiln, pressure measurement transmission device is connected with controller C data, first valve plate and second valve plate are respectively set at the air inlet and air outlet of first air induction fan and second air induction fan.This application technical scheme is cooperated by multiple systems, can realize the accurate automatic regulation and control of dangerous waste incineration device air induction negative pressure, and has working condition emergency self-switching capacity, effectively guarantees that incineration system is stable, safe operation.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for induced draft fans, and in particular to an induced draft system and control method for a rotary kiln for hazardous waste incineration. Background Technology

[0002] With increasingly stringent environmental protection requirements, the harmless disposal of hazardous waste has become a crucial issue in the field of environmental protection. Among these technologies, rotary kiln incineration has become one of the mainstream processes for hazardous waste disposal due to its wide adaptability and significant volume and weight reduction effects. The core working logic of the hazardous waste incineration rotary kiln treatment system is to decompose hazardous waste materials at high temperatures in a rotary kiln, followed by complete combustion of the flue gas in a secondary combustion chamber. This ensures the thorough decomposition of harmful pollutants such as dioxins, ultimately achieving the harmless treatment of hazardous waste. The secondary combustion chamber requires strict control of the furnace temperature above 1100℃ and a flue gas residence time of no less than 2 seconds. This process places extremely high demands on the pressure and airflow stability of the flue gas system.

[0003] As a core auxiliary equipment in the rotary kiln system for hazardous waste incineration, the induced draft system plays a crucial role in flue gas extraction and emission. Its operational stability directly determines the incineration conditions of the rotary kiln and secondary combustion chamber, the compliance of pollutant emissions, and the overall safety of the system. However, most existing induced draft systems for hazardous waste incineration rotary kilns currently employ a single induced draft fan configuration, and the control methods are primarily manual or simple semi-automatic adjustments, resulting in the following drawbacks:

[0004] Firstly, the control precision is low, making it difficult to adapt to complex operating conditions. Hazardous waste materials have complex compositions and large fluctuations in calorific value, resulting in frequent changes in flue gas volume, temperature, and pressure during incineration. Existing induced draft systems cannot respond to changes in operating conditions in real time, easily leading to problems such as negative pressure imbalance at the rotary kiln head and insufficient flue gas residence time in the secondary combustion chamber. This not only affects the sufficiency and harmlessness of hazardous waste incineration but also fails to meet the requirements of relevant environmental protection standards such as GB 18484-2020. Secondly, the system suffers from poor reliability and insufficient fault tolerance. Most existing induced draft systems are designed with a single induced draft fan. If the fan malfunctions, the system must be shut down for maintenance, causing the entire hazardous waste incineration system to stop operating and severely impacting disposal efficiency. Furthermore, the inlet and outlet valves of the induced draft fan are mostly adjusted using traditional mechanical drives, resulting in slow response times, low opening accuracy, and an inability to coordinate with flue gas parameters, further reducing the system's operational stability. Third, the control coordination is poor, lacking an integrated control mechanism. The power drive, parameter detection, and command control of the existing induced draft system are mostly independent modules, failing to form an integrated automatic control system. The detection signals of flue gas pressure and flow rate cannot be linked with the adjustment commands of induced draft fan speed and valve opening in real time, resulting in control lag and easy occurrence of air volume and pressure mismatch. This not only increases energy consumption but may also cause equipment damage or safety hazards due to flue gas leakage or excessive pressure. Although some automated control schemes in the existing technology are applied to waste incineration flue gas treatment, they are mostly aimed at bag filter dust collector systems and do not take into account the core structural characteristics of the hazardous waste incineration rotary kiln "rotary kiln + secondary combustion chamber". They cannot adapt to the special working conditions of high-temperature dusty flue gas and are difficult to achieve dynamic interlocking control between the kiln head negative pressure and the induced draft system.

[0005] Furthermore, the hydraulic drive and instrumentation control system of the existing rotary kiln for hazardous waste incineration are not closely integrated, and the displacement detection accuracy of the hydraulic actuators is insufficient, making it impossible to accurately reflect the valve opening status, resulting in a deviation between the adjustment command and the actual execution effect. Moreover, the linkage between the induced draft system and the DCS system is poor, making it difficult to achieve remote monitoring and centralized control, which is not in line with the development trend of intelligent and automated modern hazardous waste disposal equipment.

[0006] In view of the shortcomings of the existing technologies, there is an urgent need to develop an integrated and highly automated induced draft control system that can respond to changes in operating conditions in real time, achieve precise control of flue gas pressure and air volume, and is highly reliable and easy to operate and maintain. This system can solve the problems of low control accuracy, poor coordination and insufficient fault tolerance of the existing induced draft system, ensure the stability and efficiency of the hazardous waste incineration rotary kiln treatment system, and meet the increasingly stringent environmental protection and production requirements. Summary of the Invention

[0007] The main objective of this invention is to propose an induced draft system and control method for a rotary kiln for hazardous waste incineration, aiming to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention proposes a hazardous waste incineration rotary kiln induced draft system, comprising a first induced draft fan, a second induced draft fan, an induced draft fan drive motor, a first valve plate, a second valve plate, a pressure measurement and transmission device, controller A, controller B, and controller C. The first and second induced draft fans are symmetrically arranged. Each of the first and second induced draft fans has an air inlet at its lower end and an air outlet at its upper end. The air inlets of the first and second induced draft fans are respectively connected to the ends of the flue gas emission pipes of the rotary kiln and the secondary combustion chamber. The air outlets of the first and second induced draft fans are respectively connected to the exhaust flue. The output shaft of the induced draft fan drive motor is fixedly connected to the impeller input shafts of the first and second induced draft fans. The pressure measurement and transmission device is located at the kiln head of the rotary kiln and is data-connected to controller C. The first and second valve plates are respectively located at the air inlets and outlets of the first and second induced draft fans. The first and second valve plates control the opening and closing of the air inlets and outlets of the first and second induced draft fans. Both valve plates are driven by hydraulic cylinders. The hydraulic cylinders of the first and second valve plates of the first induced draft fan are connected to controller A, and the hydraulic cylinders of the first and second valve plates of the second induced draft fan are connected to controller B. Controllers A and B are connected to controller C. Controllers A or B control the hydraulic cylinder drive devices of the first and second valve plates to open and close them. The induced draft fan drive motor is equipped with a high-voltage frequency converter, which is connected to controller C. The pressure measurement and transmission device monitors the pressure value at the kiln head of the rotary kiln in real time. Controller C adjusts the frequency of the induced draft fan drive motor to achieve stepless speed regulation, thus maintaining the pressure value at the kiln head of the rotary kiln within a set range.

[0009] Optionally, it also includes a local control cabinet, which is data connected to the controller C. The local control cabinet is equipped with manual control knobs for the first valve plate and the second valve plate, as well as a manual / automatic switching button.

[0010] Optionally, the pressure measurement and transmission device includes three pressure sensors, and the pressure measurement and transmission device transmits two of the values ​​measured by the three pressure sensors to the controller C.

[0011] Optionally, the system also includes pressure flow meters, which are respectively installed at the air inlet and air outlet of the first and second induced draft fans. The pressure flow meters of the first induced draft fan are respectively connected to the controller A, and the pressure flow meters of the second induced draft fan are respectively connected to the controller B.

[0012] Optionally, the pressure range at the kiln head of the rotary kiln is set to -100 MPa to -50 MPa.

[0013] Optionally, each of the hydraulic cylinders is connected to a hydraulic pump station.

[0014] Optionally, the first valve plate is an equidistant distributed flap valve.

[0015] Optionally, the second valve plate is a slide gate valve.

[0016] On the other hand, the present invention also proposes a control method for the induced draft system of the rotary kiln for hazardous waste incineration as described above, comprising the following steps: Step 1: Normal commissioning. Confirm that the power signal is in place. Switch the local control cabinet to automatic mode. Remotely and synchronously open the first valve plate and the second valve plate of the first induced draft fan through the DCS system operation panel of controller C. When both valves are fully open, remotely start the induced draft fan drive motor at low frequency through the DCS system operation panel of controller C. Remotely put the PID interlock program into the DCS system operation panel of controller C. Adjust the frequency of the induced draft fan drive motor through controller C to achieve stepless adjustment of the speed of the induced draft fan drive motor, so that the pressure value at the kiln head of the rotary kiln is maintained within the set range. Step Two: Emergency Fault Handling. During normal operation, when the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease sharply, the DCS will issue an alarm signal, the kiln head negative pressure interlock signal will be released, and the standby second induced draft fan will start automatically at low frequency according to the normal commissioning procedure. The frequency will be gradually increased remotely and manually to ensure the negative pressure of the system. When the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease to 0, the first and second valve plates at the inlet and outlet of the first induced draft fan will begin to close until the opening degree is 0. The standby second induced draft fan will then engage the kiln head negative pressure interlock function with the rotary kiln, and the induced draft control system will complete the automatic switching function under fault conditions. Step 3: Shut down for inspection and maintenance. Switch the hydraulic system local control cabinet to manual mode. The opening degree of the induced draft fan inlet and outlet valves can be controlled locally, or the opening degree of the induced draft fan inlet and outlet valves and the frequency of the induced draft fan drive motor can be controlled remotely.

[0017] The technical solution of this invention has the following beneficial effects: It effectively solves many defects of existing hazardous waste incineration induced draft systems. The symmetrical arrangement of dual induced draft fans enhances the system's fault tolerance, preventing system shutdown due to single-unit failure and ensuring continuous processing. The integrated hydraulic and instrumentation control systems enable real-time linkage control of flue gas pressure and air volume, accurately matching the kiln head negative pressure setpoint and meeting the requirements of GB 18484-2020 standards. Hydraulic drive combined with displacement sensors ensures precise valve opening adjustment and stable and reliable actuators. The instrumentation control system's linkage alarm and interlocking control can promptly handle abnormal operating conditions, preventing excessive pollutant levels and safety hazards. The addition of manual / automatic switching functions facilitates operation and maintenance, while also enabling remote centralized management, improving the system's intelligence level, reducing energy consumption and maintenance costs, and ensuring efficient operation of the hazardous waste incineration system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the rotary kiln and secondary combustion chamber of a hazardous waste incineration rotary kiln induced draft system according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the overall structure of an induced draft system for a hazardous waste incineration rotary kiln according to an embodiment of the present invention; Figure 3 This is a partial structural schematic diagram of an induced draft system for a hazardous waste incineration rotary kiln according to an embodiment of the present invention.

[0020] Figure label: First induced draft fan 101, second induced draft fan 102, induced draft fan drive motor 103, first valve plate 104, second valve plate 105, pressure measurement and transmission device 106, controller A 107, controller B 108, controller C 109, local control cabinet 110, pressure flow meter 111.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0024] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] This invention proposes an induced draft system and control method for a rotary kiln used for hazardous waste incineration.

[0026] like Figures 1 to 3As shown, in one embodiment of the present invention, the induced draft system of the hazardous waste incineration rotary kiln includes a first induced draft fan 101, a second induced draft fan 102, an induced draft fan drive motor 103, a first valve plate 104, a second valve plate 105, a pressure measurement and transmission device 106, a controller A107, a controller B108, and a controller C109. The first induced draft fan 101 and the second induced draft fan 102 are arranged symmetrically on the left and right sides. The lower ends of the first induced draft fan 101 and the second induced draft fan 102 are respectively provided with an air inlet 112, and the upper ends of the first induced draft fan 101 and the second induced draft fan 102 are respectively provided with an air outlet 113. The air inlet of the blower 102 is connected to the end of the flue gas emission pipes of the rotary kiln 100 and the secondary combustion chamber 200, respectively. The air outlets of the first induced draft fan 101 and the second induced draft fan 102 are connected to the exhaust flue, respectively. The output shaft of the induced draft fan drive motor 103 is fixedly connected to the impeller input shafts of the first induced draft fan 101 and the second induced draft fan 102, respectively. The pressure measurement and transmission device 106 is located at the kiln head of the rotary kiln and is connected to the controller C109. The first valve plate 104 and the second valve plate 105 are located at the air inlet and outlet of the first induced draft fan 101 and the second induced draft fan 102, respectively. Valve plates 104 and 105 control the opening and closing of the air inlets and outlets of the first induced draft fan 101 and the second induced draft fan 102. Both valve plates 104 and 105 are driven by hydraulic cylinders. The hydraulic cylinders of the first valve plates 104 and 105 of the first induced draft fan 101 are connected to controller A107 via data connection. The hydraulic cylinders of the first valve plates 104 and 105 of the second induced draft fan 102 are connected to controller B108 via data connection. Controllers A107 and B108 are connected to controller C109 via data connection. The hydraulic cylinder drive devices that control the first valve plate 104 and the second valve plate 105 respectively realize the opening and closing of the first valve plate 104 and the second valve plate 105. The induced draft fan drive motor 103 is equipped with a high-voltage frequency converter, which is connected to the controller C109 for data transmission. The pressure value at the kiln head of the rotary kiln is monitored in real time through the pressure measurement and transmission device 106. The frequency of the induced draft fan drive motor 103 is adjusted through the controller C109 to realize stepless adjustment of the speed of the induced draft fan drive motor 103, so that the pressure value at the kiln head of the rotary kiln is maintained within the set range, thereby realizing the automated and stable control of flue gas pressure and air volume of the entire hazardous waste incineration system.

[0027] Specifically, the induced draft control system is used in a hazardous waste incineration rotary kiln treatment system. The core main equipment of the waste incineration rotary kiln system includes a rotary kiln 100 and a secondary combustion chamber 200 connected in sequence. The rotary kiln 100 is used for high-temperature incineration and decomposition of hazardous waste materials, and the secondary combustion chamber 200 is used for the complete combustion and harmless treatment of incineration flue gas. The induced draft control system is integrated and installed at the end of the flue gas emission pipelines of the rotary kiln 100 and the secondary combustion chamber 200.

[0028] Specifically, it also includes a local control cabinet 110, which is connected to the controller C109 via data connection. The local control cabinet 110 is equipped with manual control knobs for the first valve plate 104 and the second valve plate 105, as well as a manual / automatic switching button. The local control cabinet is equipped with manual control knobs for the inlet and outlet valves of the induced draft fan A / B, as well as a manual / automatic switching button, which can be switched to manual control mode when the furnace is shut down or under maintenance.

[0029] Specifically, the pressure measurement and transmission device 106 includes three pressure sensors. The pressure measurement and transmission device 106 transmits two of the values ​​measured by the three pressure sensors to the controller C109. The pressure measurement and transmission device integrates measurement, indication, alarm, automatic action and safety interlock. Two out of the three pressure measurement and transmission data are transmitted to the controller C. The controller C interlocks with the drive motor of the induced draft fan through central control, so that the operating frequency of the induced draft fan always matches the kiln head negative pressure set value, thereby realizing dynamic interlock control of the system negative pressure.

[0030] Specifically, it also includes a pressure flow meter 111, which is respectively installed at the air inlet and air outlet of the first induced draft fan 101 and the second induced draft fan 102. The pressure flow meter 111 of the first induced draft fan 101 is connected to the controller A107 for data connection, and the pressure flow meter 111 of the second induced draft fan 102 is connected to the controller B108 for data connection.

[0031] Specifically, the pressure range at the kiln head of the rotary kiln is set to -100 MPa to -50 MPa.

[0032] Specifically, each hydraulic cylinder is connected to a hydraulic pump station.

[0033] Specifically, the first valve plate 104 is an equidistant distributed flap valve, which controls the opening degree through the action of the hydraulic cylinder on the air outlet side. The hydraulic cylinders on the inlet and outlet sides of the induced draft fan are all equipped with integrated magnetostrictive displacement sensors, which can accurately collect the displacement signal of the hydraulic cylinder stroke to achieve opening degree control.

[0034] Specifically, the second valve plate 105 is a slide gate valve, which is fixed to the air inlet pipe by a shaft connection and the opening degree is controlled by the action of the air inlet side cylinder.

[0035] Specifically, the induced draft system includes controller A, controller B, controller C, a DCS system operation module, and supporting communication lines. Controller A and controller B establish signal connections with the magnetostrictive displacement sensors and inlet / outlet flue gas flow and pressure sensors of the inlet and outlet valve hydraulic cylinders of the two induced draft fans via wired communication. Controller C is the central control module of the system and is connected to controller A, controller B, and the induced draft fan drive control system via wired bidirectional communication. Controller C is used to centrally collect, summarize, and process the detection signals of each module, and at the same time, relying on the DCS system operation module, it completes the remote issuance of operating commands and automatic coordinated control of each controlled device.

[0036] On the other hand, the present invention also proposes a control method for the induced draft system of the rotary kiln for hazardous waste incineration as described above, comprising the following steps: Step 1: Normal commissioning. Confirm that the power signal is in place. Switch the local control cabinet to automatic mode. Remotely and synchronously open the first valve plate and the second valve plate of the first induced draft fan through the DCS system operation panel of controller C. When both valves are fully open, remotely start the induced draft fan drive motor at low frequency through the DCS system operation panel of controller C. Remotely put the PID interlock program into the DCS system operation panel of controller C. Adjust the frequency of the induced draft fan drive motor through controller C to achieve stepless adjustment of the speed of the induced draft fan drive motor, so that the pressure value at the kiln head of the rotary kiln is maintained within the set range. Step Two: Emergency Fault Handling. During normal operation, when the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease sharply, the DCS will issue an alarm signal, the kiln head negative pressure interlock signal will be released, and the standby second induced draft fan will start automatically at low frequency according to the normal commissioning procedure. The frequency will be gradually increased remotely and manually to ensure the negative pressure of the system. When the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease to 0, the first and second valve plates at the inlet and outlet of the first induced draft fan will begin to close until the opening degree is 0. The standby second induced draft fan will then engage the kiln head negative pressure interlock function with the rotary kiln, and the induced draft control system will complete the automatic switching function under fault conditions. Step 3: Shut down for inspection and maintenance. Switch the hydraulic system local control cabinet to manual mode. The opening degree of the induced draft fan inlet and outlet valves can be controlled locally, or the opening degree of the induced draft fan inlet and outlet valves and the frequency of the induced draft fan drive motor can be controlled remotely.

[0037] Specifically, the technical solution of this invention effectively solves many defects of existing hazardous waste incineration induced draft systems. It adopts a symmetrical arrangement of dual induced draft fans to improve system fault tolerance, avoid system shutdown due to single-unit failure, and ensure continuous processing. It integrates hydraulic and instrumentation control systems to achieve real-time linkage control of flue gas pressure and air volume, accurately matching the kiln head negative pressure setpoint, meeting the requirements of GB 18484-2020 standard. Hydraulic drive combined with displacement sensors ensures precise valve opening adjustment and stable and reliable actuators. The instrumentation control system features linkage alarms and interlocking control, enabling timely handling of abnormal operating conditions and preventing excessive pollutant levels and safety hazards. It adds a manual / automatic switching function for convenient operation and maintenance, while also enabling remote centralized management, improving the system's intelligence level, reducing energy consumption and maintenance costs, and ensuring efficient operation of the hazardous waste incineration system.

[0038] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An induced draft system for a rotary kiln used for hazardous waste incineration, characterized in that, The system includes a first induced draft fan, a second induced draft fan, an induced draft fan drive motor, a first valve plate, a second valve plate, a pressure measurement and transmission device, controller A, controller B, and controller C. The first and second induced draft fans are symmetrically arranged. Each of the first and second induced draft fans has an air inlet at its lower end and an air outlet at its upper end. The air inlets of the first and second induced draft fans are connected to the ends of the flue gas emission pipes of the rotary kiln and the secondary combustion chamber, respectively. The air outlets of the first and second induced draft fans are connected to the exhaust flue. The output shaft of the induced draft fan drive motor is fixedly connected to the impeller input shafts of the first and second induced draft fans, respectively. The pressure measurement and transmission device is located at the kiln head of the rotary kiln and is data-connected to controller C. The first and second valve plates are respectively located at the air inlets and outlets of the first and second induced draft fans. The valve plate controls the opening and closing of the inlet and outlet of the first and second induced draft fans. Both the first and second valve plates are driven by hydraulic cylinders. The hydraulic cylinders of the first and second valve plates of the first induced draft fan are respectively connected to controller A, and the hydraulic cylinders of the first and second valve plates of the second induced draft fan are respectively connected to controller B. Controller A and controller B are respectively connected to controller C. Controller A or controller B controls the hydraulic cylinder drive devices of the first and second valve plates to open and close them. The induced draft fan drive motor is equipped with a high-voltage frequency converter, which is connected to controller C. The pressure measurement and transmission device monitors the pressure value at the kiln head of the rotary kiln in real time. The frequency of the induced draft fan drive motor is adjusted by controller C to achieve stepless speed regulation, thus maintaining the pressure value at the kiln head of the rotary kiln within a set range.

2. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, It also includes a local control cabinet, which is connected to the controller C via data. The local control cabinet is equipped with manual control knobs for the first valve plate and the second valve plate, as well as a manual / automatic switching button.

3. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, The pressure measurement and transmission device includes three pressure sensors, and the pressure measurement and transmission device transmits two of the values ​​measured by the three pressure sensors to the controller C.

4. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, It also includes pressure flow meters, which are respectively installed at the air inlet and air outlet of the first induced draft fan and the second induced draft fan. The pressure flow meters of the first induced draft fan are respectively connected to the controller A, and the pressure flow meters of the second induced draft fan are respectively connected to the controller B.

5. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, The pressure range at the kiln head of the rotary kiln is set to -100 MPa to -50 MPa.

6. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, Each of the hydraulic cylinders is connected to a hydraulic pump station.

7. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, The first valve plate is an equidistant distributed flap valve.

8. The induced draft system for a hazardous waste incineration rotary kiln according to claim 1, characterized in that, The second valve plate is a slide gate valve.

9. The control method for the induced draft system of a hazardous waste incineration rotary kiln according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1: Normal commissioning. Confirm that the power signal is in place. Switch the local control cabinet to automatic mode. Remotely and synchronously open the first valve plate and the second valve plate of the first induced draft fan through the DCS system operation panel of controller C. When both valves are fully open, remotely start the induced draft fan drive motor at low frequency through the DCS system operation panel of controller C. Remotely put the PID interlock program into the DCS system operation panel of controller C. Adjust the frequency of the induced draft fan drive motor through controller C to achieve stepless adjustment of the speed of the induced draft fan drive motor, so that the pressure value at the kiln head of the rotary kiln is maintained within the set range. Step Two: Emergency Fault Handling. During normal operation, when the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease sharply, the DCS will issue an alarm signal, the kiln head negative pressure interlock signal will be released, and the standby second induced draft fan will start automatically at low frequency according to the normal commissioning procedure. The frequency will be gradually increased remotely and manually to ensure the negative pressure of the system. When the pressure and flow count values ​​at the inlet and outlet of the first induced draft fan decrease to 0, the first and second valve plates at the inlet and outlet of the first induced draft fan will begin to close until the opening degree is 0. The standby second induced draft fan will then engage the kiln head negative pressure interlock function with the rotary kiln, and the induced draft control system will complete the automatic switching function under fault conditions. Step 3: Shut down for inspection and maintenance. Switch the hydraulic system local control cabinet to manual mode. The opening degree of the induced draft fan inlet and outlet valves can be controlled locally, or the opening degree of the induced draft fan inlet and outlet valves and the frequency of the induced draft fan drive motor can be controlled remotely.

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