Graded heat exchange and oxygen-controlled oxidation process method based on thermal oxidation furnace system

Abstract

The invention discloses a grading heat exchange and oxygen control oxidation process method based on a thermal oxidation furnace system, and belongs to the field of waste gas purification treatment. The system comprises a furnace body, a heat accumulator and a combustion chamber, and high-temperature purified gas at an outlet of the combustion chamber can be dynamically distributed through a switching air valve. The heat exchange branch is connected with the built-in heat exchanger, and an outlet of the heat exchange branch can eject and flow back part of flue gas subjected to heat exchange to the oxidizing chamber through the ejector for accurate oxygen supplementation. The system is further provided with a sensor group and a controller. The technological method is executed by a controller, the current working condition is judged according to predefined conditions by receiving oxygen content, temperature, flow and concentration signals in real time, a corresponding control mode is automatically switched, and the heat exchange amount and the backflow oxygen supplementation amount of the built-in heat exchanger are cooperatively controlled by adjusting the opening degree of a switching air valve. The problems that traditional RTO waste heat recovery efficiency is low, operation control is extensive, and oxygen content control is inaccurate are solved, and efficient heat exchange, safe low-nitrogen combustion and working condition self-adaptive operation are achieved.

Description

Technical Field

[0001] This invention belongs to the field of waste gas purification and treatment, and particularly relates to a process method based on staged heat exchange and oxygen-controlled oxidation of a thermal oxidizer system. Background Technology

[0002] Regenerative thermal oxidizers are important equipment for treating volatile organic compounds, but existing technologies have the following shortcomings: Conventional RTOs use external heat exchangers for waste heat recovery, drawing high-temperature purified gas out of the furnace for heat exchange via external pipelines. This design suffers from problems such as low heat exchange efficiency (typically <90%), complex piping, and the risk of pipe deformation and weld cracking due to thermal expansion and contraction at high temperatures of 700-950℃.

[0003] Existing heat exchange processes generally employ a fixed airflow design, which cannot be dynamically adjusted according to fluctuations in exhaust gas conditions. High flow rates result in excess heat waste, while low flow rates lead to insufficient heat exchange and incomplete oxidation, resulting in inefficient energy consumption control.

[0004] Conventional RTOs introduce ambient temperature combustion air (containing 21% oxygen) through a burner for oxygen supplementation, while simultaneously burning natural gas to supplement heat. This method presents three problems: 1) Ambient temperature air carries away a significant amount of furnace heat, requiring additional fuel for reheating; 2) The accuracy of combustion air volume adjustment is low (oxygen content fluctuates within ±1.5%), easily resulting in excessively high or low oxygen content; 3) High-oxygen environments easily generate thermal NO. x Furthermore, there is a risk of localized overheating.

[0005] Therefore, there is an urgent need for an RTO system and method that can integrate efficient waste heat recovery, dynamically adapt to fluctuations in operating conditions, and achieve safe, efficient, stable, and adaptive operation. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention provides a process method based on staged heat exchange and oxygen-controlled oxidation using a thermal oxidizer system, which integrates efficient waste heat recovery, dynamic adaptation to operating condition fluctuations, and precise and controllable oxygen-deficient combustion.

[0007] To achieve the above objectives, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a thermal oxidation furnace system, comprising: The furnace body has an oxidation chamber inside, which contains a heat storage body and a combustion chamber. The flue gas outlet of the combustion chamber is connected to a heat exchange branch and a bypass branch connected in parallel with the heat exchange branch. A switching damper is installed on the heat exchange branch to control the flow rate of flue gas flowing through the heat exchange branch by adjusting its opening. An internal heat exchanger is installed inside the furnace to exchange heat with the flowing flue gas. An injector, whose injection inlet is connected to the outlet side of the built-in heat exchanger and whose outlet is connected to the oxidation chamber via a pipeline, is used to inject a portion of the flue gas flowing through the built-in heat exchanger back to the oxidation chamber. The sensor group includes at least an oxygen content sensor for monitoring the oxygen content in the oxidation chamber, a temperature sensor for monitoring the temperature, and a flow sensor for monitoring the flow rate of the exhaust gas. The controller is signal-connected to the drive mechanism of the sensor group and the switching air valve; the controller is configured to: based on the feedback signal from the sensor group, adjust the opening of the switching air valve to coordinately control the heat exchange of the built-in heat exchanger and the amount of supplementary oxygen flue gas returning to the oxidation chamber through the ejector.

[0008] Optionally, the built-in heat exchanger includes a main frame and a heat exchange unit consisting of multiple sets of U-shaped heat exchange tubes fixed to the main frame, and the built-in heat exchanger is provided with a hollow area for reducing the flow resistance of flue gas.

[0009] Optionally, the diameter of the U-shaped heat exchange tube is φ25-φ50mm, and the tube spacing is 50-80mm.

[0010] Optionally, the switching air valve includes a rotating shaft, a valve plate connected to the rotating shaft, and a drive mechanism for driving the rotating shaft, wherein the valve plate is rotatably connected to the heat exchange branch.

[0011] Optionally, a high-temperature resistant seal is provided at the connection interface between the built-in heat exchanger and the furnace body.

[0012] In a second aspect, the present invention provides a process method for staged heat exchange and oxygen-controlled oxidation in a thermal oxidizer system as described in the first aspect, executed by a controller, comprising the following steps: The system receives feedback signals from the sensor array in real time, including oxygen content in the oxidation chamber, combustion chamber temperature, and exhaust gas inlet flow rate and concentration. Based on the predefined conditions satisfied by the feedback signal, the current operating condition of the system is determined, and the corresponding control mode is executed, wherein: If the first predefined condition is met, it is determined to be a start-up condition, and the first control mode is executed: the switching air valve is closed and the burner is started; If the second predefined condition is met, it is determined to be a normal operating condition, and the second control mode is executed: the switching air valve is controlled to open to the first opening range, and part of the heat exchanged flue gas is returned through the ejector; If the third predefined condition is met, it is determined to be a high-load condition, and the third control mode is executed: the switching air valve is controlled to open to a second opening range greater than the first opening range; If the fourth predefined condition is met, it is determined to be a state of fluctuating operating conditions, and the fourth control mode is executed: dynamically adjust the opening of the switching air valve to stabilize the oxygen content in the oxidation chamber; If the fifth predefined condition is met, it is determined to be a low-load stability condition, and the fifth control mode is executed: the burner is started for auxiliary heating, and the switching air valve is controlled to maintain the third opening range.

[0013] Optionally, the first predefined condition is: the oxidation chamber temperature is lower than a first temperature threshold. The second predefined condition is: the oxidation chamber temperature is higher than the third temperature threshold, and the exhaust gas inlet flow rate and concentration are within the preset design reference range; The third predefined condition is: the exhaust gas inlet flow rate is greater than the first flow rate threshold, or the exhaust gas concentration is greater than the first concentration threshold, or the oxidation chamber temperature is greater than the second temperature threshold. The fourth predefined condition is: the real-time change rate of the exhaust gas inlet flow rate or concentration exceeds the preset change rate threshold. The fifth predefined condition is: the exhaust gas concentration is continuously lower than the second concentration threshold for more than a preset delay time, or the oxidation chamber temperature is continuously lower than the third temperature threshold for more than a preset delay time; Among them, the first temperature threshold < the third temperature threshold < the second temperature threshold; the second concentration threshold < the first concentration threshold.

[0014] Optionally, in the second control mode, the first opening range is 10° to 40°; in the third control mode, the second opening range is 60° to 90°; and in the fifth control mode, the third opening range is 20° to 30°.

[0015] Optionally, in the second and third control modes, the flue gas returned to the oxidation chamber through the injector is purified flue gas that has been cooled by heat exchanger by the built-in heat exchanger and has an oxygen content of 3%-5%.

[0016] Optionally, when executing the fourth control mode, the controller adjusts the opening of the switching air valve to control the oxygen content fluctuation in the oxidation chamber to within ±0.5%.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention features an internal heat exchanger directly installed within the furnace body, eliminating the need for external piping and resolving the deformation and cracking issues caused by thermal expansion and contraction, thus reducing the operational failure rate. Furthermore, the U-shaped / spiral tube design and central hollow structure of the internal heat exchanger, combined with the switching air valve for flue gas distribution, significantly improve heat exchange efficiency.

[0018] The purified gas, which has cooled down after passing through the built-in heat exchanger but whose oxygen content is stabilized at 3-5%, is returned to the oxidation chamber as a precise and controllable oxygen source through an ejector. This completely replaces the crude method of supplementing oxygen with room temperature air, forming an internal cycle of matter and energy.

[0019] In this invention, the controller comprehensively analyzes oxygen content, temperature, flow rate, and exhaust gas concentration signals in real time, and can automatically and accurately determine the current system operating condition and switch to the corresponding optimal control mode; by adjusting the opening of the switching air valve, real-time and precise coordinated control of waste heat recovery and recirculation oxygen replenishment is achieved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a thermal oxidation furnace system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a built-in heat exchanger according to an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Furnace body; 2. Regenerator; 3. Oxidation chamber; 4. Switching air valve; 5. Built-in heat exchanger; 51. Main frame; 52. Heat exchange unit; 53. Fluid inlet; 54. Fluid outlet; 6. Injector; 7. Combustion chamber. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] Example 1

[0026] like Figure 1 and Figure 2 As shown, a thermal oxidation furnace system of the present invention includes: The furnace body 1 has an oxidation chamber 3 inside, and a heat storage body 2 and a combustion chamber 7 are provided inside the oxidation chamber 3. The flue gas outlet of the combustion chamber 7 is connected to a heat exchange branch and a bypass branch connected in parallel with the heat exchange branch. Switching air valve 4 is installed on the heat exchange branch and is used to control the flow rate of flue gas flowing through the heat exchange branch by adjusting its opening. An internal heat exchanger 5 is arranged inside the furnace body 1, and its inlet is connected to the outlet of the heat exchange branch for heat exchange of the flowing flue gas. The injector 6 has its injection inlet connected to the outlet side of the built-in heat exchanger 5, and its outlet connected to the oxidation chamber 3 through a pipeline, for injecting a portion of the flue gas flowing through the built-in heat exchanger 5 back to the oxidation chamber 3. The sensor group includes at least an oxygen content sensor (such as an online oxygen analyzer) for monitoring the oxygen content in the oxidation chamber 3, a temperature sensor for monitoring the temperature, and a flow sensor (such as a flow meter) for monitoring the flow rate of the waste gas. The controller is signal-connected to the sensor group and the drive mechanism of the switching air valve 4; the controller is configured to: based on the feedback signal from the sensor group, adjust the opening of the switching air valve 4 to coordinately control the heat exchange of the built-in heat exchanger 5 and the amount of supplementary oxygen flue gas returning to the oxidation chamber 3 through the ejector 6.

[0027] In this embodiment, the built-in heat exchanger 5 includes a main frame 51 and a heat exchange unit 52 consisting of multiple sets of U-shaped heat exchange tubes fixed to the main frame 51. The built-in heat exchanger 5 has a perforated area to reduce the resistance to flue gas flow. The diameter of the U-shaped heat exchange tubes is φ25-φ50mm, and the tube spacing is 50-80mm. The entire heat exchanger is made of Hastelloy C-276 high-temperature alloy. The fluid inlet 53 and fluid outlet 54 of the built-in heat exchanger 5 are located outside the fluid.

[0028] The switching damper 4 includes a rotating shaft, a valve plate connected to the rotating shaft, and a drive mechanism that drives the rotating shaft. The valve plate is rotatably connected to the heat exchange branch. In this embodiment, the drive mechanism uses an electric actuator, which can achieve continuous opening adjustment from 0-90°.

[0029] A process method based on staged heat exchange and oxygen-controlled oxidation using a thermal oxidizer system includes: Real-time feedback signals are received from the sensor array, including oxygen content in oxidation chamber 3, temperature of oxidation chamber 3, and inlet flow rate and concentration of exhaust gas. Based on the predefined conditions satisfied by the feedback signal, the current operating condition of the system is determined, and the corresponding control mode is executed, wherein: If the temperature of oxidation chamber 3 is lower than the first temperature threshold T1, it is determined to be a start-up condition, and the first control mode is executed: control the switching air valve 4 to close and start the burner to safely and quickly raise the temperature to the oxidation temperature; If the temperature of oxidation chamber 3 is higher than the third temperature threshold T3, and the inlet flow rate and concentration of exhaust gas are within the preset design reference range, it is determined to be a normal operating condition and the second control mode is executed: control the switching air valve 4 to open to the first opening range of 10°-40°, and make part of the heat exchanged flue gas return through the ejector 6 to maintain the basic hypoxic environment and stable heat exchange. If the exhaust gas inlet flow rate is greater than the first flow rate threshold, or the exhaust gas concentration is greater than the first concentration threshold, or the temperature of oxidation chamber 3 is greater than the second temperature threshold T2, it is determined to be a high load condition and the third control mode is executed: control the switching air valve 4 to open to the second opening range of 60° to 90°, which is greater than the first opening range. If the real-time change rate of the exhaust gas inlet flow or concentration exceeds the preset change rate threshold, it is determined to be a working condition fluctuation state, and the fourth control mode is executed: dynamically adjust the opening of the switching air valve 4 to stabilize the oxygen content in the oxidation chamber 3, and control the oxygen content fluctuation in the oxidation chamber 3 within ±0.5% by adjusting the opening of the switching air valve 4. If the exhaust gas concentration remains below the second concentration threshold for more than a preset delay time, or if the temperature of oxidation chamber 3 remains below the third temperature threshold T3 for more than a preset delay time, it is determined to be a low-load stability condition, and the fifth control mode is executed: start the burner to assist heating, and control the switching air valve 4 to maintain the third opening range of 20 to 30°.

[0030] Among them, the first temperature threshold < the third temperature threshold < the second temperature threshold; the second concentration threshold < the first concentration threshold.

[0031] In the second and third control modes, the flue gas that flows back to the oxidation chamber 3 through the injector 6 is purified flue gas that has been cooled by heat exchanger 5 and has an oxygen content of 3%-5%.

[0032] Example as follows: 1. Cold start stage: Operating conditions: After the equipment is restarted after maintenance, the temperature of oxidation chamber 3, T, is equal to the ambient temperature, such as 50℃, which is much lower than the first temperature threshold T1 (such as 200℃). System Action: The controller determines that the first predefined condition is met and immediately executes the first control mode (start-up condition). It controls the switching air valve 4 to be completely closed (0°C), and simultaneously starts the burner to burn natural gas, rapidly heating the furnace and regenerator 2. In this stage, purging precedes heating to ensure an initial oxygen content ≥15%, until the temperature of regenerator 2 >750°C.

[0033] 2. Steady-state operation phase under design load: Operating conditions: The production unit operates at full load, and the exhaust gas concentration C is stable at approximately 5500-6500 mg / m³. 3 The exhaust gas inlet flow rate Q is stable at approximately 28,000-32,000 m³ / h. 3 Within the range of / h, the temperature T of oxidation chamber 3 rises and stabilizes at approximately 820-850℃.

[0034] System Action: All parameters are within the preset design baseline range, and T>T3 (700℃). The controller determines that the second predefined condition is met, and the system enters the second control mode (normal operating condition): the opening of the air valve 4 is switched and stabilized within approximately 30°-40° (first opening range). The system stably recovers waste heat through the built-in heat exchanger 5, and simultaneously, through the ejector 6, it induces a suitable amount of heat-exchanged flue gas (temperature approximately 500-600℃, oxygen content 3-5%) for recirculation, precisely maintaining the oxygen content in the oxidation chamber 3 at approximately 4.0%, achieving efficient and economical continuous operation.

[0035] 3. Peak production (high load) phase: Operating condition: During the concentrated feeding of high-concentration materials or equipment purging in the production unit, the concentration of exhaust gas C suddenly rises to approximately 8000 mg / m³ in a short period of time. 3 It exceeded the first concentration threshold C1 (5000 mg / m³). 3 Meanwhile, the inlet flow rate Q of the exhaust gas may also exceed 35,000 m³ / h, and the temperature T of oxidation chamber 3 will rise rapidly to above 880°C.

[0036] System action: The controller monitors in real time that C>C1 (and / or Q>20000m) 3 When the temperature reaches 850℃, the system immediately determines that the third predefined condition is met and seamlessly switches to the third control mode (high load condition): the opening of switching damper 4 rapidly increases to 70°-90° (second opening range), allowing most of the high-temperature flue gas (800-900℃) to flow through the heat exchanger U-tube, maximizing the recovery of excess heat. The controller adjusts the opening of switching damper 4 to ensure that the oxygen content is strictly stabilized within the target range of 3-5%, effectively suppressing the risk of local overheating (>1000℃) and thermal NO2 caused by sudden increases in heat load. x The generation of .

[0037] 4. Production switchover or temporary load reduction (severe fluctuation) phase: Operating condition: Due to batch change or temporary load reduction on the production line, the inlet concentration C of the exhaust gas increases from 6000 mg / m³ within minutes. 3 Sharply dropped to 3000 mg / m 3 Its rate of change (>30%) far exceeds the preset rate of change threshold. The temperature of oxidation chamber 3 faces the risk of a sudden drop.

[0038] System Action: The controller detects an excessive rate of concentration change and immediately determines that the fourth predefined condition is met, causing the system to enter the fourth control mode (fluctuation state). With stable oxygen content as the primary objective, the controller calculates a control command within 1.5 seconds, rapidly adjusting the opening of switching valve 4 from 70° to 30°. This rapid response dynamically matches the changing heat exchange demands, maintaining sufficient return oxygen supply while minimizing heat loss. This successfully controls instantaneous fluctuations in oxygen content within ±0.5% and temperature fluctuations ≤±10℃, preventing system instability.

[0039] 5. Low-load (stability maintenance) phase at night or on weekends: Operating conditions: The production unit is operating at low load or in a heat preservation state, and the exhaust gas concentration C is maintained at approximately 2000 mg / m³ for an extended period. 3 The concentration level is low (below the second concentration threshold C2), and the temperature T of oxidation chamber 3 slowly drops to about 680°C (below T3), and this state continues for more than the preset delay time (e.g., 5 minutes).

[0040] System Action: The controller determines that the fifth predefined condition is met, and the system switches to the fifth control mode (low-load stability maintenance). The burner automatically starts and operates at low power (e.g., 30% of rated power) to supplement the system's heat. Simultaneously, the opening setting of the switching damper 4 is set and locked at 20°-30°. This opening ensures minimal flue gas circulation and oxygen supplementation, while allowing the heat supplemented by the burner to be efficiently used to maintain the core furnace temperature, enabling the system to operate safely with minimal energy consumption.

[0041] 6. Load recovery phase: Operating condition: After several hours of stable operation at low load, the production unit resumes a higher load, and the exhaust gas concentration rises to >5000 mg / m³. 3 The temperature of oxidation chamber 3 also stabilized at >800℃.

[0042] System Action: The controller detects that the concentration and temperature have been consistently above the stability threshold and automatically exits the fifth control mode. Based on real-time parameters, the system reassesses whether the current condition meets the third predefined condition, and then seamlessly switches back to the third control mode (high load condition). The air valve opening is automatically adjusted to the corresponding value, the burner stops, and the system re-enters the high-efficiency self-heating operation state.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A thermal oxidation furnace system, characterized in that, include: The furnace body contains an oxidation chamber, which is equipped with a heat storage medium and a combustion chamber. The flue gas outlet of the combustion chamber is connected to a heat exchange branch and a bypass branch connected in parallel with the heat exchange branch. A switching damper is installed on the heat exchange branch to control the flow rate of flue gas flowing through the heat exchange branch by adjusting its opening. An internal heat exchanger is installed inside the furnace body, and its inlet is connected to the outlet of the heat exchange branch for heat exchange of the flowing flue gas. An injector, whose injection inlet is connected to the outlet side of the built-in heat exchanger and whose outlet is connected to the oxidation chamber via a pipeline, is used to inject a portion of the flue gas flowing through the built-in heat exchanger back to the oxidation chamber. The sensor group includes at least an oxygen content sensor for monitoring the oxygen content in the oxidation chamber, a temperature sensor for monitoring the temperature, and a flow sensor for monitoring the flow rate of the exhaust gas. The controller is signal-connected to the drive mechanism of the sensor group and the switching air valve; the controller is configured to: based on the feedback signal from the sensor group, adjust the opening of the switching air valve to coordinately control the heat exchange of the built-in heat exchanger and the amount of supplementary oxygen flue gas returning to the oxidation through the ejector.

2. The thermal oxidizer system according to claim 1, characterized in that, The built-in heat exchanger includes a main frame and a heat exchange unit consisting of multiple sets of U-shaped heat exchange tubes fixed to the main frame, and the built-in heat exchanger is provided with a hollow area for reducing the flow resistance of flue gas.

3. The thermal oxidation furnace system according to claim 2, characterized in that, The diameter of the U-shaped heat exchange tube is φ25-φ50mm, and the tube spacing is 50-80mm.

4. The thermal oxidizer system according to claim 1, characterized in that, The switching air valve includes a rotating shaft, a valve plate connected to the rotating shaft, and a drive mechanism for driving the rotating shaft. The valve plate is rotatably connected to the heat exchange branch.

5. The thermal oxidizer system according to claim 1, characterized in that, The connection interface between the built-in heat exchanger and the furnace body is equipped with a high-temperature resistant seal.

6. A process method based on staged heat exchange and oxygen-controlled oxidation of a thermal oxidizer system as described in any one of claims 1-5, characterized in that, Performed by the controller, the process includes the following steps: The system receives feedback signals from the sensor array in real time, including oxygen content in the oxidation chamber, combustion chamber temperature, and exhaust gas inlet flow rate and concentration. Based on the predefined conditions satisfied by the feedback signal, the current operating condition of the system is determined, and the corresponding control mode is executed, wherein: If the first predefined condition is met, it is determined to be a start-up condition, and the first control mode is executed: the switching air valve is closed and the burner is started; If the second predefined condition is met, it is determined to be a normal operating condition, and the second control mode is executed: the switching air valve is controlled to open to the first opening range, and part of the heat exchanged flue gas is returned through the ejector; If the third predefined condition is met, it is determined to be a high-load condition, and the third control mode is executed: the switching air valve is controlled to open to a second opening range greater than the first opening range; If the fourth predefined condition is met, it is determined to be a state of fluctuating operating conditions, and the fourth control mode is executed: dynamically adjust the opening of the switching air valve to stabilize the oxygen content in the oxidation chamber; If the fifth predefined condition is met, it is determined to be a low-load stability condition, and the fifth control mode is executed: the burner is started for auxiliary heating, and the switching air valve is controlled to maintain the third opening range.

7. The process method according to claim 6, characterized in that: The first predefined condition is: the oxidation chamber temperature is lower than the first temperature threshold. The second predefined condition is: the oxidation chamber temperature is higher than the third temperature threshold, and the exhaust gas inlet flow rate and concentration are within the preset design reference range; The third predefined condition is: the exhaust gas inlet flow rate is greater than the first flow rate threshold, or the exhaust gas concentration is greater than the first concentration threshold, or the oxidation chamber temperature is greater than the second temperature threshold. The fourth predefined condition is: the real-time change rate of the exhaust gas inlet flow rate or concentration exceeds the preset change rate threshold. The fifth predefined condition is: the exhaust gas concentration is continuously lower than the second concentration threshold for more than a preset delay time, or the oxidation chamber temperature is continuously lower than the third temperature threshold for more than a preset delay time; Among them, the first temperature threshold < the third temperature threshold < the second temperature threshold; the second concentration threshold < the first concentration threshold.

8. The process method according to claim 6 or 7, characterized in that, In the second control mode, the first opening range is 10° to 40°; in the third control mode, the second opening range is 60° to 90°; and in the fifth control mode, the third opening range is 20° to 30°.

9. The process method according to claim 6, characterized in that, In the second and third control modes, the flue gas that flows back to the oxidation chamber through the injector is purified flue gas that has been cooled by the built-in heat exchanger and has an oxygen content of 3%-5%.

10. The process method according to claim 6, characterized in that, When the fourth control mode is executed, the controller adjusts the opening of the switching air valve to keep the oxygen content fluctuation in the oxidation chamber within ±0.5%.

Images