A control system and method for neutralizing and treating non-condensable gases from waste tire pyrolysis

Abstract

This invention relates to a control system for neutralizing non-condensable gases from waste tire pyrolysis, comprising a neutralization reaction unit, a storage and execution unit, a detection unit, and a control unit. The neutralization reaction unit is a packed-bed scrubbing tower, with an inlet pipe and an outlet pipe at the bottom and a delivery pipe and an outlet pipe at the top. The storage and execution unit includes a neutralizing agent storage tank and a precision metering pump. The neutralizing agent storage tank stores neutralizing agent and is connected to the precision metering pump, which is connected to the delivery pipe. The outlet pipe is connected to the neutralizing agent storage tank. The detection unit includes an online pH meter installed on the delivery pipe between the outlet pipe and the neutralizing agent storage tank. The control unit is a PLC controller used to control and adjust the neutralizing agent dosage. This system can achieve efficient removal of acidic pollutants and ensure compliant emissions, avoiding waste and secondary pollution caused by excessive use of neutralizing agents.

Description

Technical Field

[0001] This invention relates to industrial waste gas purification and control technology, and in particular to a system and method for automatic and precise neutralization treatment of non-condensable gas from waste tire pyrolysis with large compositional fluctuations. Background Technology

[0002] During the pyrolysis of waste tires, a portion of non-condensable gases, known as "non-condensable gases," is produced. The main components of non-condensable gases are small-molecule hydrocarbons such as H2, CH4, and CO, as well as permanent gases. These are typically recycled as fuel for the pyrolysis process, achieving energy self-sufficiency. However, because tires contain sulfur (vulcanizing agents) and chlorine-containing additives (such as chloroprene rubber), the non-condensable gases are rich in sulfides such as H2S, COS, and CS2, as well as HCl gas.

[0003] These gases are acidic, and directly recovering them as fuel would present two major problems: (1) Environmental pollution: When non-condensable gases are burned in boilers or burners, sulfides are converted into SO2, which is released into the atmosphere along with HCl, causing acid rain and environmental pollution. (2) Equipment corrosion: Before combustion, acidic gases will corrode the delivery pipeline, gas storage tank and burner; after combustion, acidic gases in low-temperature flue gas will still corrode the chimney and equipment.

[0004] The common approach to this problem is to pass the non-condensable gas into an alkaline scrubbing tower for neutralization and absorption, but this approach generally suffers from the following drawbacks: (1) Control lag: The concentration of acidic substances in non-condensable gases fluctuates drastically with the pyrolysis conditions (such as tire type and pyrolysis temperature stage). The traditional method of adding alkali solution at a fixed flow rate either results in incomplete neutralization leading to excessive emissions, or excessive alkali solution causing waste and excessively high salinity in wastewater; (2) Reliance on manual labor: Operators need to frequently check the pH value and manually adjust the valves or pumps, resulting in slow response and unstable effects; (3) Lack of predictability: The changes in the composition of non-condensable gases cannot be predicted, and the system is always in a "passive response" state, resulting in poor quality control.

[0005] Therefore, there is an urgent need for a neutralization control system that can sense, predict, and automatically and accurately adjust in real time. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing non-condensable gas neutralization processes by providing a control system and method for neutralizing non-condensable gases from waste tire pyrolysis. Through a feedforward-feedback composite control strategy, the method achieves precise and automatic control of the neutralizing agent dosage, maximizing the conservation of neutralizing agent consumption while ensuring that acidic pollutants are discharged in compliance with standards.

[0007] The technical solution adopted in this invention is as follows: A control system for neutralizing non-condensable gases from waste tire pyrolysis includes a neutralization reaction unit, a storage and execution unit, a detection unit, and a control unit. Neutralization reaction unit: The neutralization reaction unit is a packed scrubbing tower. The bottom of the packed scrubbing tower is equipped with an air inlet pipe and a liquid outlet pipe, and the top of the packed scrubbing tower is equipped with a liquid delivery pipe and an air outlet pipe. The air inlet pipe is used to send the non-condensable gas generated by waste tire pyrolysis into the packed scrubbing tower, the liquid delivery pipe is used to send the neutralizing agent into the packed scrubbing tower, the air outlet pipe is used to discharge the neutralized non-condensable gas, and the liquid outlet pipe is used to discharge the neutralizing agent. Storage Execution Unit: The storage execution unit includes a neutralizing agent storage tank and a precision metering pump. The neutralizing agent storage tank is connected to the precision metering pump via a delivery pipeline. The precision metering pump is connected to the liquid delivery pipeline of the packed scrubbing tower via a delivery pipeline. The liquid outlet pipeline of the packed scrubbing tower is connected to the neutralizing agent storage tank via a delivery pipeline. Simultaneously, the precision metering pump is electrically connected to the control unit. The neutralizing agent storage tank stores the neutralizing agent, which is an alkaline scrubbing liquid. The precision metering pump receives control signals from the control unit, continuously adjusts the neutralizing agent dosage flow rate, extracts the neutralizing agent from the storage tank, and delivers it to the packed scrubbing tower. Detection Unit: The detection unit includes an online pH meter, which is installed on the delivery pipeline between the liquid outlet pipeline of the packed scrubbing tower and the neutralizing agent storage tank. The online pH meter is electrically connected to the control unit and is used to monitor the acidity and alkalinity of the circulating neutralizing agent in real time, thereby reflecting the degree of neutralization reaction in the packed scrubbing tower. Control Unit: The control unit includes a PLC controller, which receives signals from the detection unit, generates control signals and sends them to the precision metering pump in the storage execution unit to control and adjust the amount of neutralizing agent added.

[0008] Furthermore, the detection unit also includes an online monitoring instrument, which is installed at the outlet pipe of the packed scrubbing tower and is electrically connected to the PLC controller. The online monitoring instrument is a gas detector capable of detecting gas concentration, used to detect the concentration of SO2 and HCl in the exhaust gas, and transmits the concentration signal to the PLC controller.

[0009] Furthermore, the gas circulation pipe is provided at the outlet pipe of the packed scrubbing tower. One end of the gas circulation pipe is connected to the outlet pipe, and a suction pump and a one-way valve are installed on the gas circulation pipe. The other end of the gas circulation pipe is connected to the inlet pipe.

[0010] Furthermore, the packed-type scrubbing tower is surrounded by several spray pipes, each with several spray holes; each spray pipe is connected to a liquid delivery pipe at the top of the packed-type scrubbing tower.

[0011] Furthermore, the spray pipes are arranged in a ring or arc shape on the tower wall of the packed scrubbing tower.

[0012] Furthermore, when the spray pipe is arranged in an arc shape, the angle between the tangent of the arc and the horizontal line is 3°~5°; at the same time, the spray pipe is arranged symmetrically at the top and bottom.

[0013] Furthermore, the neutralizing agent is one or more of sodium hydroxide solution, lime milk, or sodium carbonate solution.

[0014] A control method for the above-mentioned control system for neutralizing and treating non-condensable gases from waste tire pyrolysis includes the following steps: Step S1, Data Acquisition and Prediction: Real-time acquisition of main process parameters of waste tire pyrolysis in the preceding process, and calculation and prediction of the concentration of acidic substances in non-condensable gas through PLC controller; Step S2, Feedforward Coarse Adjustment: Based on the predicted concentration of acidic substances, calculate the initial dosage reference amount of neutralizing agent, and drive the precision metering pump to add neutralizing agent into the packed scrubbing tower according to the initial dosage reference amount; Step S3, Feedback Fine-tuning: The online pH meter monitors the pH value of the neutralizing agent circulating in the pipeline in real time and feeds it back to the PLC controller; the PLC controller compares the measured pH value with the preset pH threshold, outputs a correction amount, and adds the correction amount to the initial dosage reference amount to obtain the real-time dosage, thereby achieving precise fine-tuning of the dosage. Step S4, Adaptive Learning: The concentration of acidic substances in the neutralized gas monitored in real time by the online monitoring instrument is compared with the predicted concentration of acidic substances obtained in step S1, the initial dosage benchmark obtained in step S2, and the real-time dosage obtained in step S3. The PLC controller is optimized periodically to improve the prediction accuracy.

[0015] The beneficial effects of this invention are: 1. Precise control and emission reduction to meet standards: Through dual-core regulation of feedforward coarse adjustment and feedback fine adjustment, the alkaline washing liquid is always kept in the optimal reaction pH range, thereby ensuring efficient removal of acidic gases and stable emission compliance.

[0016] 2. Energy saving and consumption reduction: It avoids excessive addition of neutralizing agent, significantly reduces the consumption of reagents and operating costs, and also reduces the amount of high-salt wastewater generated.

[0017] 3. Rapid response and strong adaptability: The feedforward coarse adjustment control can act in advance according to the changes in the cracking conditions, overcoming the large lag of traditional systems and having a strong adaptability to fluctuations in non-condensable gas composition.

[0018] 4. Fully automated and intelligent: No manual intervention is required, reducing labor intensity and eliminating the uncertainty of human operation.

[0019] 5. Possesses self-learning capability: By comparing the final emission data with the real-time monitoring data of the online monitoring instrument, the PLC controller can continuously optimize itself, becoming "smarter" with use and achieving higher and higher control accuracy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to the present invention.

[0021] Figure 2 This is a schematic diagram of the cross-sectional distribution of the spray pipes in a packed scrubbing tower arranged in a ring.

[0022] Figure 3 This is a schematic diagram of the cross-sectional distribution of the spray pipes in a packed scrubbing tower, which are arranged in an arc shape.

[0023] In the diagram: 1. Packed scrubbing tower; 2. Online monitoring instrument; 3. Online pH meter; 4. Neutralizing agent storage tank; 5. Precision metering pump. Air inlet pipe 101, liquid outlet pipe 102, liquid delivery pipe 103, air outlet pipe 104, conveying pipe 105, gas circulation pipe 106, one-way valve 107, air pump 108, spray pipe 109. Detailed Implementation

[0024] To better understand the above-described objects, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may be practiced in other ways different from those described herein, and therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Example 1:

[0026] like Figure 1 The control system shown includes a neutralization reaction unit, a storage and execution unit, a detection unit, and a control unit for neutralizing non-condensable gases from waste tire pyrolysis. Neutralization Reaction Unit: The neutralization reaction unit is a packed scrubbing tower 1. The bottom of the packed scrubbing tower 1 is provided with an air inlet pipe 101 and a liquid outlet pipe 102, and the top of the packed scrubbing tower 1 is provided with a liquid delivery pipe 103 and an air outlet pipe 104. The air inlet pipe 101 is used to send the non-condensable gas generated by waste tire pyrolysis into the packed scrubbing tower 1, the liquid delivery pipe 103 is used to send the neutralizing agent into the packed scrubbing tower 1, the air outlet pipe 104 is used to discharge the neutralized non-condensable gas, and the liquid outlet pipe 102 is used to discharge the neutralizing agent. The non-condensable gas enters from the air inlet pipe 101 at the bottom of the packed scrubbing tower 1 and comes into countercurrent contact with the neutralizing agent sprayed down from the liquid delivery pipe 103, resulting in a neutralization reaction. Storage Execution Unit: The storage execution unit includes a neutralizing agent storage tank 4 and a precision metering pump 5. The neutralizing agent storage tank 4 is connected to the precision metering pump 5 via a delivery pipe 105. The precision metering pump 5 is connected to the liquid delivery pipe 103 of the packed scrubbing tower 1 via a delivery pipe 105. The liquid outlet pipe 102 of the packed scrubbing tower 1 is connected to the neutralizing agent storage tank 4 via a delivery pipe 105. Simultaneously, the precision metering pump 5 is electrically connected to the control unit. The neutralizing agent storage tank 4 is used to store the neutralizing agent, which is an alkaline washing liquid, specifically one or more of sodium hydroxide solution (NaOH solution), lime milk (Ca(OH)2 solution), or sodium carbonate solution. The precision metering pump 5 is used to receive a 4-20mA control signal from the control unit, steplessly adjust the neutralizing agent dosing flow rate, extract the neutralizing agent from the neutralizing agent storage tank 4, and deliver it to the packed scrubbing tower 1. Detection Unit: The detection unit includes an online pH meter 3, which is installed on the conveying pipe 105 between the liquid outlet pipe 102 of the packed scrubbing tower 1 and the neutralizing agent storage tank 4. The online pH meter 3 is electrically connected to the control unit and is used to monitor the acidity and alkalinity of the circulating neutralizing agent in real time, thereby reflecting the degree of neutralization reaction in the packed scrubbing tower 1. Control Unit: The control unit includes a PLC controller, which receives signals from the detection unit, generates control signals and sends them to the precision metering pump 5 in the storage execution unit to control and adjust the amount of neutralizing agent added, thereby controlling the neutralization reaction.

[0027] In this embodiment, the detection unit further includes an online monitoring instrument 2, which is installed at the outlet pipe 104 of the packed scrubbing tower 1 and is electrically connected to the PLC controller. The online monitoring instrument 2 is a gas detector capable of detecting the concentration of SO2 and HCl gases, such as an HK-7200A / 7201 air detector, used to detect the concentration of SO2 and HCl in the exhaust gas and transmit the concentration signal to the PLC controller.

[0028] In this embodiment, a gas circulation pipe 106 is provided at the outlet pipe 104 of the packed scrubbing tower 1. One end of the gas circulation pipe 106 is connected to the outlet pipe 104, and a vacuum pump 108 and a one-way valve 107 are provided on the gas circulation pipe 106. The other end of the gas circulation pipe 106 is connected to the inlet pipe 101.

[0029] In this embodiment, the packed-type scrubbing tower 1 is internally arranged with several spray pipes 109. Each spray pipe 109 has a number of spray holes evenly distributed at intervals. The spray direction of the spray holes is horizontal or slightly downward at 3°~5°, thereby ensuring that the neutralizing agent is evenly sprayed from the inner wall of the packed-type scrubbing tower 1 towards the axis. Each spray pipe 109 is connected to a liquid delivery pipe 103 at the top of the packed-type scrubbing tower 1. The spray pipes 109 are arranged in multiple horizontally and parallel rings (e.g., Figure 2 ) or multiple arcs spaced symmetrically (such as Figure 3 The spray pipe 109 is installed on the tower wall of the packed scrubbing tower 1. When the spray pipe 109 is arranged in an arc shape, the angle between the tangent of the arc and the horizontal line is 5°; at the same time, the spray pipe 109 is arranged symmetrically vertically (e.g., ...). Figure 3 (As shown).

[0030] Example 2:

[0031] The PLC controller in this embodiment is a programmable logic controller. The PLC controller has a built-in preset sulfur and chlorine concentration soft measurement module and a PID control algorithm. The sulfur and chlorine concentration soft measurement module is a mathematical model. Based on the pyrolysis reactor temperature, pyrolysis time, and feed rate in the main process parameters of waste tire pyrolysis, it uses the built-in preset calculation model to predict the concentration of acidic substances (i.e., the concentration of total sulfur and total chlorine) in non-condensable gas in real time. Based on the prediction result, it outputs a feedforward control signal to the precision metering pump 5 to realize feedforward control. Then, through the PID control algorithm, combined with the feedback signal of the online pH meter 3, the dosage is precisely fine-tuned to form a composite control. A control method for the above-mentioned control system for neutralizing and treating non-condensable gases from waste tire pyrolysis includes the following steps: Step S1, Data Acquisition and Prediction: Real-time acquisition of main process parameters of waste tire pyrolysis in the preceding process, and prediction of the concentration of acidic substances in non-condensable gas through the sulfur and chlorine concentration soft measurement module built into the PLC controller. Step S2, Feedforward coarse adjustment: Based on the predicted concentration of acidic substances, calculate the initial dosage reference amount of neutralizing agent, and drive the precision metering pump 5 to add neutralizing agent into the packed scrubbing tower 1 according to the initial dosage reference amount; Step S3, Feedback Fine-tuning: The online pH meter 3 monitors the pH value of the neutralizing agent circulating in the pipeline in real time and feeds it back to the PLC controller; the PLC controller compares the measured pH value with the preset pH threshold (such as pH=7-8), outputs a correction amount through the PID control algorithm built into the PLC controller, and adds the correction amount to the initial dosage reference amount to obtain the real-time dosage, thereby realizing precise fine-tuning of the dosage; Step S4, Adaptive Learning: The concentration of acidic substances (SO2 and HCl concentrations) in the neutralized gas monitored in real time by the online monitoring instrument 2 is compared with the predicted concentration of acidic substances obtained in step S1, the initial dosage reference amount obtained in step S2, and the real-time dosage amount obtained in step S3. The sulfur and chlorine concentration soft measurement module built into the PLC controller is optimized periodically to improve the prediction accuracy.

[0032] Example 3: System Workflow Step S1, System Start-up: The waste tire pyrolysis process begins, non-condensable gas is generated, the control system is started, data acquisition and prediction are performed, and the main process parameters of waste tire pyrolysis are collected.

[0033] Step S2, Feedforward coarse adjustment: Step S21: The PLC controller reads the current temperature (480℃ in this embodiment) and cumulative feed amount (2 tons processed in this embodiment) of the pyrolysis reactor in real time.

[0034] Step S22: The sulfur and chlorine concentration soft measurement module calculates the predicted total sulfur concentration of the current non-condensable gas as 8000 ppm based on the built-in calculation model (in this embodiment, the sulfur release rate of the treated tire is about 0.8% at 480°C).

[0035] Step S23: Based on the predicted total sulfur concentration, the PLC controller queries the preset dosage curve, calculates the required initial dosage of NaOH solution (initial neutralizing agent flow rate) as 2.0 L / min, and sends a command to control the precision metering pump 5 to add NaOH solution at this flow rate.

[0036] Step S3, Feedback and Fine-tuning: Step S31: After the neutralizing agent (NaOH solution) circulating in the packed scrubbing tower 1 reacts with the non-condensable gas, the pH value of the NaOH solution is detected in real time by the online pH meter 3.

[0037] Step S32: Assume that due to batch changes in waste tires, the actual sulfur concentration is higher than the predicted total sulfur concentration, causing the pH value of the circulating NaOH solution to begin to decrease (when the pH value of the NaOH solution drops from the set threshold of 7.5 to 7.0).

[0038] Step S33: The PID control algorithm immediately takes action and calculates the preset increase in dosage (i.e., feedback correction) of 0.3 L / min based on the deviation (-0.5).

[0039] Step S34: Finally, the actual dosage of the precision metering pump 5 = feedforward amount (initial dosage reference amount 2.0 L / min) + feedback correction amount (0.3 L / min) = 2.3 L / min.

[0040] Step S4, Steady-state operation and adaptive learning optimization: Step S41: Through feedback correction, the pH value of the circulating neutralizing agent is pulled back and stabilized at 7.5.

[0041] Step S42: Online monitoring instrument 2 shows SO2 concentration of 80 mg / m³. 3 It is lower than the national emission standard (100 mg / m³). 3 ).

[0042] Step S43: The system records the deviation between the predicted and actual dosage for subsequent fine-tuning of the sulfur and chlorine concentration soft measurement module.

[0043] This system enables efficient, economical, and environmentally friendly purification of non-condensable gases with complex and variable compositions, providing key technological support for the green and sustainable development of the waste tire pyrolysis industry.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A control system for neutralizing and treating non-condensable gases from waste tire pyrolysis, characterized in that, It includes a neutralization reaction unit, a storage execution unit, a detection unit, and a control unit; Neutralization reaction unit: The neutralization reaction unit is a packed scrubbing tower. The bottom of the packed scrubbing tower is provided with an air inlet pipe and a liquid outlet pipe, and the top of the packed scrubbing tower is provided with a liquid delivery pipe and an air outlet pipe. The air inlet pipe is used to send the non-condensable gas generated by waste tire pyrolysis into the packed scrubbing tower, the liquid delivery pipe is used to send the neutralizing agent into the packed scrubbing tower, the air outlet pipe is used to discharge the neutralized non-condensable gas, and the liquid outlet pipe is used to discharge the neutralizing agent. Storage execution unit: The storage execution unit includes a neutralizing agent storage tank and a precision metering pump. The neutralizing agent storage tank stores neutralizing agent. The neutralizing agent storage tank is connected to the precision metering pump through a delivery pipeline. The precision metering pump is connected to the liquid delivery pipeline of the packed scrubbing tower through a delivery pipeline. The liquid outlet pipeline of the packed scrubbing tower is connected to the neutralizing agent storage tank through a delivery pipeline. At the same time, the precision metering pump is electrically connected to the control unit. Detection Unit: The detection unit includes an online pH meter, which is installed on the delivery pipeline between the outlet pipeline of the packed washing tower and the neutralizing agent storage tank. The online pH meter is electrically connected to the control unit and is used to monitor the pH of the circulating neutralizing agent in real time. Control Unit: The control unit includes a PLC controller, which receives signals from the detection unit, generates control signals and sends them to the precision metering pump in the storage execution unit to control and adjust the amount of neutralizing agent added.

2. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 1, characterized in that, The detection unit also includes an online monitoring instrument, which is installed at the outlet pipe of the packed scrubbing tower and is electrically connected to the PLC controller. The online monitoring instrument is used to detect the concentration of SO2 and HCl in the exhaust gas and transmit the concentration signal to the PLC controller.

3. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 2, characterized in that, The packing scrubbing tower is equipped with a gas circulation pipe at the outlet pipe. One end of the gas circulation pipe is connected to the outlet pipe, and a suction pump and a one-way valve are installed on the gas circulation pipe. The other end of the gas circulation pipe is connected to the inlet pipe.

4. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 3, characterized in that, The packed-type scrubbing tower is surrounded by several spray pipes, each with several spray holes; each spray pipe is connected to a liquid delivery pipe at the top of the packed-type scrubbing tower.

5. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 4, characterized in that, The spray pipes are arranged in a ring or arc shape on the tower wall of the packed scrubbing tower.

6. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 5, characterized in that, When the spray pipe is arranged in an arc shape, the angle between the tangent of the arc and the horizontal line is 3°~5°; at the same time, the spray pipe is arranged symmetrically at the top and bottom.

7. The control system for neutralizing and treating non-condensable gases from waste tire pyrolysis according to claim 6, characterized in that, The neutralizing agent is one or more of sodium hydroxide solution, lime milk, or sodium carbonate solution.

8. A control method for a control system based on any one of claims 1 to 7 for neutralizing and treating non-condensable gases from waste tire pyrolysis, characterized in that, Includes the following steps: Step S1, Data Acquisition and Prediction: Real-time acquisition of main process parameters of waste tire pyrolysis in the preceding process, and calculation and prediction of the concentration of acidic substances in non-condensable gas through PLC controller; Step S2, Feedforward Coarse Adjustment: Based on the predicted concentration of acidic substances, calculate the initial dosage reference amount of neutralizing agent, and drive the precision metering pump to add neutralizing agent into the packed scrubbing tower according to the initial dosage reference amount; Step S3, Feedback Fine-tuning: The online pH meter monitors the pH value of the neutralizing agent circulating in the pipeline in real time and feeds it back to the PLC controller; the PLC controller compares the measured pH value with the preset pH threshold, outputs a correction amount, and adds the correction amount to the initial dosage reference amount to obtain the real-time dosage, thereby achieving precise fine-tuning of the dosage. Step S4, Adaptive Learning: The concentration of acidic substances in the neutralized gas monitored in real time by the online monitoring instrument is compared with the predicted concentration of acidic substances obtained in step S1, the initial dosage benchmark obtained in step S2, and the real-time dosage obtained in step S3. The PLC controller is optimized periodically to improve the prediction accuracy.

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