Low-calorific-value associated gas ultralow-nitrogen flameless combustion system

Abstract

The invention discloses a low-calorific-value associated gas ultralow-nitrogen flameless combustion system, which relates to the technical field of combustion control and comprises a gas acquisition module, a premixing control module, a low-calorific-value gas pre-mixing module, a low-calorific-value gas pre-mixing module and a low-calorific-value gas pre-mixing module, multivariable cooperative control is adopted to adjust the mixing proportion of the low-heating-value gas with the stable pressure and the air, and premixed gas with the stable flow is obtained; according to the ultralow-nitrogen flameless combustion system for the low-heating-value associated gas, the combustion process is adjusted through a recirculation channel and dynamic power distribution, combustion state data are collected through a flame probe and a temperature sensor, airflow distribution of the porous ceramic combustor is adjusted according to the data, and finally stable combustion output is achieved. The method can effectively improve the combustion efficiency and stability of the low-heating-value gas and reduce emission, and is suitable for efficient and clean utilization of the low-heating-value gas such as industrial waste gas.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion control, and particularly to an ultra-low nitrogen flameless combustion system for low calorific value associated gas. Background Art

[0002] In current low calorific value gas combustion systems, how to efficiently utilize gases with different methane contents while ensuring combustion stability is a key technical problem. Traditional systems generally rely on fixed premixing control strategies and are difficult to cope with the combustion calorific value fluctuations caused by dynamic changes in methane concentration.

[0003] Especially when it is necessary to adjust the premixing ratio and flow rate in real time according to the pressure and composition of the inlet gas, it is extremely easy to cause instability in the combustion process, such as flashback and flameout. In addition, to reduce nitrogen oxide (NOx) emissions, flameless combustion technology is currently widely used. Although this technology has advantages in environmental protection, it has higher requirements for controlling the temperature field and mixing uniformity in the combustion chamber, thus increasing the design and operation difficulties of the combustion control system. To further optimize emission control, existing systems also introduce a flue gas recirculation channel to adjust the thermal field distribution in the combustion chamber, reduce local temperature peaks, and inhibit NOx generation. However, while reducing the temperature, this method may affect the combustion efficiency and increase the complexity of the coordinated regulation of the flow field and thermal field by the control system. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultra-low nitrogen flameless combustion system for calorific value associated gas to solve the problems existing in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: An ultra-low nitrogen flameless combustion system for low calorific value associated gas, comprising:

[0006] A gas acquisition module that acquires low calorific value gas through an inlet pipeline valve group to obtain dry low calorific value gas;

[0007] A premixing control module that uses multivariable coordinated control to adjust the mixing ratio of low calorific value gas with stable pressure and air to obtain premixed gas with stable flow rate;

[0008] A flashback prevention module that performs flashback prevention treatment on the premixed gas with stable flow rate through a flame arrester, acquires the flow rate data of the treated premixed gas using a flow sensor, and combines load adaptive adjustment to optimize the gas delivery efficiency to obtain flashback prevention treated premixed gas;

[0009] A flameless combustion module that performs flameless combustion on the flashback prevention treated premixed gas through a porous ceramic burner, and uses a recirculation channel to adjust the recirculation air flow ratio according to the feedback of the combustion chamber temperature and flue gas exhaust temperature, and combines dynamic power distribution to obtain combustion gas with a balanced thermal field;

[0010] The flame detection module collects the spectral characteristics of the flame state in the combustion gas with a balanced thermal field through a flame probe, obtains the gas temperature in the combustion chamber and the exhaust gas temperature using a temperature sensor, combines with a flow sensor to obtain the flow data of the premixed gas for flashback prevention treatment, and generates a combustion state data set by smoothing the control signal.

[0011] The stable output module generates a first control signal, adjusts the air flow distribution in the ceramic pores of the porous ceramic burner using the first control signal, optimizes the operating parameters by combining motor temperature rise monitoring and fault diagnosis signals. If the flow data and the combustion chamber temperature meet the preset deviation threshold setting, it generates a second control signal, locks the burner parameters through the second control signal, and obtains a stable combustion output.

[0012] Preferably, a vapor-liquid separation device is used in the gas acquisition module to separate the liquid impurities in the gas, and dry low-calorific value gas is obtained.

[0013] Preferably, to obtain a premixed gas with stable flow in the premix control module, it also includes continuously collecting the inlet pressure data of the dry low-calorific value gas through a high-precision pressure sensor, and processing the pressure signal using a low-pass filter algorithm to obtain a filtered inlet pressure signal.

[0014] Preferably, to obtain a premixed gas with stable flow in the premix control module, it also includes performing pressure stabilization treatment on the dry low-calorific value gas through a voltage stabilizing device. For the pressure deviation in the filtered inlet pressure signal, a proportional gain adjustment is used to generate the control output amplitude, and the integral time constant is combined to eliminate the steady-state error, obtaining low-calorific value gas with stable pressure.

[0015] Preferably, to obtain a premixed gas with stable flow in the premix control module, it also includes using an infrared gas analyzer to detect the methane concentration in the low-calorific value gas with stable pressure in real time, querying the pre-established dynamic ratio database, obtaining the flow ratio coefficient corresponding to the methane content, and determining the methane content ratio parameter.

[0016] Preferably, to obtain a premixed gas with stable flow in the premix control module, it also includes using a premixing device to adjust the mixing ratio of the low-calorific value gas with stable pressure and air according to the filtered inlet pressure signal and the methane content ratio parameter, using multivariable coordinated control to obtain the premixed gas.

[0017] Preferably, obtaining the premixed gas with stable flow rate in the premixed control module further includes driving a gas delivery pump through a variable-frequency motor, precisely adjusting the pump speed by using variable-frequency speed control, monitoring the operating state by combining real-time speed feedback, and adjusting the flow rate of the premixed gas by using differential predictive control for the filtered inlet pressure signal and methane content ratio parameter. If the methane concentration is lower than the preset methane concentration threshold, the low-methane protection logic is triggered to reduce the pump output power, and the premixed gas with stable flow rate is obtained.

[0018] Preferably, the premixed control module includes a methane content detection device and a proportional regulating valve, and the proportional regulating valve dynamically adjusts the mixing ratio of air and low-calorific-value gas according to the output signal of the methane content detection device.

[0019] Preferably, the flame arrester in the anti-backfire module is of a metal corrugated structure or a ceramic honeycomb structure, which is used to improve the backfire suppression effect.

[0020] Preferably, it further includes an inlet pipeline valve group, a vapor-liquid separation device, a flow device, a pressure stabilizing device, and a gas main pipeline valve group connected in sequence. The gas main pipeline valve group is respectively connected with a gas cut-off device and a gas ignition pipeline valve group. The gas ignition pipeline valve group is connected to a flame arrester, the flame arrester is connected to a flameless combustion device, the flameless combustion device is connected to a boiler, the gas cut-off device is connected in series with an electric valve, the electric valve is connected to an auxiliary combustion pipeline valve group, and the auxiliary combustion pipeline valve group is also connected to the flameless combustion device. The inlet pipeline valve group is also connected to an inlet auxiliary combustion valve group, the inlet auxiliary combustion valve group is connected to a blower, and the blower is also connected to the auxiliary combustion pipeline valve group.

[0021] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0022] This low-calorific-value associated gas ultra-low nitrogen flameless combustion system obtains low-calorific-value gas through the inlet pipeline valve group, and after vapor-liquid separation and pressure stabilization treatment, it detects the methane concentration in real time and conducts dynamic ratio matching, uses multivariable collaborative control to adjust the mixing ratio with air, precisely controls the flow rate of the premixed gas by driving a gas delivery pump through a variable-frequency motor, and conducts flameless combustion after anti-backfire treatment with a flame arrester. The present invention also adopts a recirculation channel and dynamic power distribution to regulate the combustion process, collects combustion state data through a flame probe and a temperature sensor, and adjusts the air flow distribution of the porous ceramic burner according to the data, finally realizing stable combustion output. This method can effectively improve the combustion efficiency and stability of low-calorific-value gas, reduce emissions, and is suitable for the efficient and clean utilization of low-calorific-value gases such as industrial waste gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the system module connection diagram of the present invention;

[0024] Figure 2 It is the process flow diagram of the present invention.

[0025] In the figure: 1. Inlet pipeline valve group; 2. Gas-liquid separation device; 3. Flow device; 4. Pressure stabilization device; 5. Main gas pipeline valve group; 6. Inlet combustion-supporting valve group; 7. Fan; 8. Gas cut-off device; 9. Gas ignition pipeline valve group; 10. Electric valve; 11. Combustion-supporting pipeline valve group; 12. Flame arrester; 13. Flameless combustion device; 14. Boiler. Specific embodiments

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] As Figure 1 shown, the present invention provides a technical solution: a low-calorific-value associated gas ultra-low nitrogen flameless combustion system, including:

[0028] A gas acquisition module that obtains low-calorific-value gas through the inlet pipeline valve group to obtain dry low-calorific-value gas;

[0029] A premixing control module that uses multi-variable collaborative control to adjust the mixing ratio of low-calorific-value gas with stable pressure and air to obtain premixed gas with stable flow;

[0030] An anti-backfire module that performs anti-backfire treatment on the premixed gas with stable flow through a flame arrester, obtains the flow data of the treated premixed gas using a flow sensor, and combines load adaptive adjustment to optimize the gas delivery efficiency to obtain the premixed gas with anti-backfire treatment;

[0031] A flameless combustion module that performs flameless combustion on the premixed gas with anti-backfire treatment through a porous ceramic burner, and uses a recirculation channel to feedback according to the combustion chamber temperature and flue gas exhaust temperature, and combines dynamic power distribution to adjust the recirculation air flow ratio to obtain combustion gas with a balanced heat field;

[0032] A flame detection module that collects the flame state spectral characteristics in the combustion gas with a balanced heat field through a flame probe, obtains the combustion chamber gas temperature and flue gas exhaust temperature using a temperature sensor, combines the flow data of the premixed gas with anti-backfire treatment obtained by the flow sensor, and uses control signal smoothing processing to generate a combustion state data set;

[0033] A stable output module generates a first control signal, uses the first control signal to adjust the air flow distribution in the pores of the porous ceramic burner, optimizes the operating parameters by combining motor temperature rise monitoring and fault diagnosis signals, and generates a second control signal if the flow data and the combustion chamber temperature meet the preset deviation threshold setting. The burner parameters are locked through the second control signal to obtain a stable combustion output.

[0034] First, in the gas acquisition stage, an external low-calorific value gas source, such as associated oilfield gas, is connected through the inlet pipeline valve group. The main components of this type of gas are usually methane, ethane, a small amount of nitrogen and sulfides. Its calorific value is preliminarily estimated to be not less than 3 MJ / m 3 Between. To ensure subsequent combustion stability, the system filters and dries the raw gas to remove water vapor, oil mist and particulate impurities. Entering the premixing control stage, the core lies in controlling the mixing ratio of low-calorific value gas and air so that the generated premixed gas has a stable flow rate and pressure while maintaining an appropriate air-fuel ratio. The volume ratio of air to gas is commonly measured by the "λ value" (i.e., the ratio of the actual air supply to the theoretical air required for combustion), and this value is usually controlled between 1.1 and 1.2 to ensure lean-burn flameless combustion. For example, if the low-calorific value gas flow rate per unit time is Qf (unit: m 3 / h), its calorific value is LHV (unit: MJ / m 3 ), the theoretical air demand can be expressed as: Qa = Qf × LHV / (η × Hu), where Qa is the theoretical air flow rate, η is the combustion efficiency (assumed to be 0.95), and Hu is the heat provided per cubic meter of air (about 3.7 MJ / m 3)。The system detects Qf in real time through gas flow sensors and pressure sensors, and then the central control module calculates and adjusts the opening of the air proportion valve to keep the mixed gas within the above λ value range all the time. The anti-backfire module uses the physical structure of the flame arrester to cut off the flame that may propagate reversely, and at the same time introduces a flow feedback mechanism to detect the gas flow velocity v in real time. If the detected value is lower than the safety threshold v_min (such as 0.5 m / s), the system adaptively increases the fan speed or reduces the cross-section of the gas passage to ensure that the flow velocity returns above the critical zone and avoid flame re-roll. The key of the flameless combustion module is to use a porous ceramic burner. The gas mixes and diffuses evenly in the porous medium, and then burns in a planar form to avoid the formation of local high-temperature flames. The thermal conductivity and heat capacity of the ceramic help to maintain the temperature balance in the combustion zone and reduce the generation of NOx at the same time. To stabilize the thermal field, the system sets up a recirculating gas passage to return a proportion β of the high-temperature gas after combustion to the front end to mix with the premixed gas again. This proportion is dynamically adjusted by the following empirical model: β = k × (Tt - Ts); where: Tt is the temperature of the combustion chamber, Ts is the temperature of the flue gas discharge, and k is the proportionality coefficient, which is set according to the furnace type experience. This adjustment realizes the balance of the thermal field distribution and improves the combustion efficiency. The flame detection module uses a spectral flame probe to identify the radiation signals in specific wavelength bands in the flame (such as the luminescence characteristics of CH* and OH* free radicals), combines the readings of the temperature sensor and the flow data in the previous section, and removes high-frequency disturbances through a signal smoothing algorithm to generate a three-variable dataset including flow rate, temperature, and spectral intensity, which is used to judge whether the combustion state is stable. Finally, in the stable output module, the system adjusts the air flow pore distribution in different regions of the porous ceramic burner through the first control signal. For example, the aperture is increased in the area with low heat load to enhance the local gas supply; at the same time, the motor temperature rise parameters and abnormal diagnosis information are monitored to adjust the operating parameters in real time. If it is determined that both the combustion flow rate and the chamber temperature are within the set thresholds (such as ±5%), the system issues a second control signal to lock the current combustion parameters and maintain stable output. Through the coordination and control of the above whole process, not only the efficient and clean utilization of low-calorie gas is realized, but also the continuity, safety and environmental protection performance of the whole combustion process are ensured, and it has good industrial applicability.

[0035] Through the modular structure design, the system effectively integrates multiple functions such as gas purification, mixing control, anti-backfire, safe combustion and intelligent detection, improving the combustion safety and system stability. The multi-variable coordinated control and recirculating air flow regulation mechanism ensure high combustion efficiency and balanced thermal field distribution, effectively suppressing the generation of NOx; at the same time, signal fusion and adaptive regulation enhance the system robustness, with excellent self-correction and fault protection capabilities. In addition, the flameless combustion design greatly reduces the visible flame and thermal shock, achieving the environmental protection goal of ultra-low emissions. The system has low operating noise and strong adaptability to load changes, and is suitable for complex industrial scenarios.

[0036] In the gas acquisition module, a vapor-liquid separation device is used to separate liquid impurities in the gas, obtaining dry low-calorific value gas. In this embodiment, the structure of the gas acquisition module is further optimized. By introducing a vapor-liquid separation device, the purity of the low-calorific value gas before entering the combustion system is effectively improved. Due to the complex sources of low-calorific value gas, it often contains water vapor, oil mist or other liquid impurities. If these liquid components directly enter the combustion system, it will lead to incomplete combustion, reduced energy efficiency and even safety risks such as deflagration. Therefore, a set of vapor-liquid separation devices is set at the inlet of this system as the core link of gas purification. Specifically, this separation device adopts a combination of inertial separation and condensation separation. First, the low-calorific value gas enters the separation cavity. The gas flow velocity suddenly decreases and changes direction in the pipeline. Due to the significant density difference between the gas and the liquid, the liquid droplets cannot turn flexibly with the airflow due to their large inertia, so they are thrown towards the inner wall of the separator and then collected in the bottom liquid collection tank through the wall liquid film and discharged. The efficiency of this process depends on the gas flow velocity, the droplet diameter and the channel geometry. In the system design, it is ensured that the average flow velocity at the gas inlet is controlled at about 10 meters per second, so that the droplets with a diameter of more than 50 microns have enough momentum to achieve inertial separation. Then, the gas enters the condensation separation area. In this area, by setting a metal cooling tube group, the gas temperature is reduced below the dew point. Under this temperature condition, the originally gaseous water vapor and light hydrocarbon components start to liquefy, attach to the cooling surface and then slide down along the wall for collection. To ensure the condensation effect, the system calculates that the target cooling temperature needs to be about 5 degrees Celsius lower than the original gas dew point temperature. For example, when the gas pressure is normal pressure and the dew point is 30 degrees Celsius, the temperature in the cooling area needs to be stably controlled within 25 degrees Celsius. The required cooling power can be estimated through a table lookup and an empirical formula: the heat required for condensation is equal to the water vapor content in the unit volume of gas multiplied by its condensation latent heat, and then multiplied by the hourly flow rate, that is, the total cooling energy consumption required per hour. This calculation process is implemented in words in the system design as: "First, evaluate the moisture content (grams per cubic meter) in the unit gas, multiply it by the vaporization latent heat of water (about 2257 joules per gram), and then combine it with the hourly gas treatment volume (cubic meters per hour) to finally obtain the required refrigeration power for the cooling section (in kilowatts). After the vapor-liquid separation is completed, the obtained gas enters the subsequent premixing control module after drying treatment. Its moisture content has decreased significantly, and the typical value is lower than 0.5%. This treatment significantly improves the stability, thermal efficiency and safety of the subsequent combustion process.

[0037] In this embodiment, by introducing a vapor-liquid separation device, the dryness of the gas before entering the combustion system is significantly improved, avoiding risks such as corrosion, flameout, and detonation of the burner caused by liquid impurities from the source, and at the same time reducing incomplete combustion by-products that may be generated during combustion, such as carbon monoxide and unburned hydrocarbons. Especially when dealing with biogas or associated gas from oilfields with large fluctuations in water content, this module can automatically adjust the condensation temperature according to the incoming gas dew point to achieve dynamic and efficient separation. In addition, the precisely controlled flow rate and cooling temperature zone design ensure high dehumidification efficiency without introducing an additional energy consumption burden, effectively guaranteeing the operation stability and emission control of the entire system during the combustion stage.

[0038] Obtaining pre-mixed gas with stable flow rate in the pre-mixing control module also includes continuously collecting the inlet pressure data of the dry low-calorific value gas through a high-precision pressure sensor, and processing the pressure signal using a low-pass filter algorithm to obtain the filtered inlet pressure signal. In this embodiment, to further improve the stability and control accuracy of the pre-mixed gas flow rate, a high-precision pressure sensor and a signal filtering algorithm are integrated in the pre-mixing control module to continuously obtain and optimize the pressure state of the dry gas before entering the mixing cavity. Due to the instability of the source of low-calorific value gas, its transportation process is often affected by factors such as source pressure fluctuations, pipeline vibrations, or equipment switching. If not handled, it will directly lead to disorder of the pre-mixing ratio and even cause unstable combustion. First, the high-precision pressure sensor is arranged at the position before the gas enters the pre-mixing mixer to continuously collect the original inlet gas pressure data per unit time. This type of sensor usually has a resolution accuracy at the millibar level and a sampling frequency of dozens of Hertz or more, and can effectively capture the pressure change trend and instantaneous impact. However, directly using the original pressure data is easily interfered by instantaneous noise. Therefore, after the data is collected, the system smooths it through a low-pass filter algorithm embedded in the control system. Low-pass filtering is an algorithm that only retains the low-frequency change trend in the data and suppresses high-frequency disturbances. Its essence is to introduce weighted averaging between the current data and historical data. For example, the system weights and averages the pressure value at each current moment and the filtered output at the previous moment. The choice of the proportional weight depends on the sampling interval and the expected response speed. If a fast response is desired, the weight of the current value is large; if strong anti-interference is required, the weight of the historical value is higher. In specific implementation, the control system processes the original pressure values collected within each second, and weights and averages them with the previous processing result to generate the current "filtered pressure value". This processing method can effectively eliminate the pressure mutations caused by air flow jitter, electromagnetic interference, or mechanical vibration, making the data for subsequent adjustment of the air proportion valve more stable and reliable. The filtered pressure signal is then sent to the pre-mixing ratio control logic to be matched and corrected with the current set ratio of fuel gas to air, ensuring that when the source gas pressure fluctuates, the system can still maintain the target air-fuel ratio unchanged by dynamically adjusting the air flux, thereby maintaining the flow stability of the pre-mixed gas.

[0039] By introducing a high-precision pressure sensor and a low-pass filtering processing algorithm, the system realizes real-time suppression of the gas source fluctuations in the premixing stage, significantly improving the component consistency and flow velocity stability of the premixed gas. Especially under the conditions of rapid load changes or unstable source gas pressure, it can effectively avoid the combustion fluctuation problems caused by instantaneous disturbances. In addition, this strategy reduces the pressure on the response speed of the air conditioning system, helps to extend the service life of the control valve and actuator, and improves the overall robustness and regulation accuracy of the system.

[0040] Obtaining the premixed gas with stable flow rate in the premix control module also includes performing pressure stabilization processing on the dry low calorific value gas through a voltage stabilizing device. For the pressure deviation in the filtered inlet pressure signal, a proportional gain adjustment is used to generate the control output amplitude, and the integral time constant is combined to eliminate the steady-state error, obtaining the low calorific value gas with stable pressure.

[0041] In this embodiment, to further enhance the ability of the premixing control module to ensure the stability of gas flow, a voltage stabilizing device and a proportional-integral regulation strategy are introduced based on the filtered signal to achieve precise control of the inlet pressure. The gas source enters the voltage stabilizing processing unit after gas-liquid separation and drying. The front section of this unit receives the inlet pressure signal that has been processed by the low-pass filtering algorithm. This signal represents the current actual pressure state of the gas and is compared in real time with the preset target inlet pressure value. The difference between the two is the "pressure deviation", which reflects the difference between the current system operating state and the ideal state. The system activates the regulation strategy for this pressure deviation: First, the deviation is linearly amplified through the proportional gain regulation module. That is, when the pressure deviation is large, the control system outputs a large regulation command; when the pressure deviation approaches zero, the regulation amplitude also decreases accordingly, so as to ensure that the system has a sensitive response ability. The magnitude of the proportional gain determines the sensitivity of the regulation. If it is set too high, it may cause oscillations, and if it is too low, the regulation will be sluggish. To solve the problem of "steady-state error" that may exist due to proportional regulation - that is, the system cannot keep the actual pressure at the set target for a long time under the condition of no external disturbance - the present invention further introduces an integral regulation link. The system accumulates the pressure deviation over a continuous period of time and acts on the regulation signal weighted by the integral time constant. Simply put, if the pressure deviates from the set value for a long time, even if the deviation is small, the integrator will gradually accumulate this error and generate an additional correction amount, thereby driving the control valve to continue fine-tuning until the error is completely eliminated. The setting of the integral time constant determines the persistence and slowness of the correction effect, which is generally adjusted according to the system response speed. The combined action of the above proportional gain regulation and integral correction forms a common proportional-integral control strategy, and its output is used to drive the gas regulating valve (such as an electric regulating valve or a servo regulating valve) in the voltage stabilizing device. The regulating valve finely controls the opening of the gas passage so that the pressure of the passing gas is always maintained near the set target, achieving continuous stability of the inlet gas pressure. The low-calorific value gas after the pressure is stabilized will be sent to the subsequent mixing chamber for proportional premixing with air, and then enter the combustion module to complete the front-end gas source regulation part of the entire combustion control process.

[0042] By introducing a proportional-integral regulation mechanism on the basis of filtering, this embodiment greatly improves the response speed and regulation accuracy of the system to gas source pressure fluctuations. Especially when there are long-term small deviations in the inlet pressure, it can achieve active fine-tuning and finally eliminate the residual error, ensuring the stability of the system's long-term operation. This control method not only optimizes the stability of the premixed gas, but also delays the mechanical fatigue of the valve and actuator, which helps to extend the equipment maintenance cycle and improve the operation reliability. In addition, this voltage stabilizing scheme has good flexibility in adapting to different gas source fluctuation conditions and can be widely applied to various low-calorific value gas scenarios such as coke oven gas, biogas, and associated gas.

[0043] Obtaining premixed gas with stable flow rate in the premixing control module further includes using an infrared gas analyzer to detect the methane concentration in the low calorific value gas with stable pressure in real time, querying the pre-established dynamic ratio database, obtaining the flow ratio coefficient corresponding to the methane content, and determining the methane content ratio parameter.

[0044] In this embodiment, in view of the strong volatility of the components of the low calorific value gas, the system introduces an infrared gas analyzer to perform real-time component detection on the gas with stable pressure before entering the premixing module, especially paying attention to the change of methane content. Thus, by querying the preset database, the ratio coefficient of air to gas is dynamically adjusted to achieve intelligent adjustment of the air-fuel ratio and precise matching of the premixed flow rate. The infrared gas analyzer irradiates the gas to be measured with an infrared light source of a specific wavelength. Since methane molecules have the ability to selectively absorb infrared light of a specific wavelength, the system calculates the volume fraction of methane by measuring the degree of light intensity attenuation. The measurement results are output to the central control system in the form of real-time data streams, and the refresh period is generally a few seconds, which can reflect the fluctuations of the gas source components in real time. The system has pre-established a set of dynamic ratio databases, which record the optimal air-gas flow ratio coefficients corresponding to different methane volume fractions through experimental calibration and engineering experience data. For example, if the methane concentration is 30%, the volume ratio of air to gas is 6.5:1; if the methane concentration drops to 20%, it needs to be increased to 7.8:1 to maintain the same calorific value output of combustion. This database can cover the full range of methane concentrations from 10% to 60% and supports obtaining intermediate values by interpolation method. When the infrared analyzer detects the methane content in the current gas, the control system automatically reads the corresponding database entry to obtain the air-gas flow ratio coefficient required at the current concentration. This coefficient is called the "methane content ratio parameter", and then it is passed to the air control valve control module. According to the current gas flow feedback, the volume of air to be sent is dynamically calculated, so as to adjust the composition of the premixed gas and ensure that the mixing ratio in the premixing chamber is always within the control range of efficient combustion. This adjustment process is automatically repeated every time the methane concentration is refreshed, enabling the system to quickly respond and timely correct the mixing ratio even under the input of a gas source with rapid fluctuations in methane content, ensuring the stability and efficiency of the combustion process.

[0045] This embodiment significantly improves the adaptability of the system to the fluctuations of the components of the low calorific value gas. Especially when dealing with multi-component and frequently changing gases such as coke oven gas, biogas or associated oilfield gas, through the cooperation of the infrared analyzer and the dynamic database for control, the methane content can be tracked in real time and the air supply can be precisely adjusted to prevent incomplete combustion or detonation risks caused by air-fuel ratio imbalance. This strategy further enhances the combustion efficiency of the system, reduces the emission level, and extends the service life of the ceramic burner, having good industrial application value and promotion potential.

[0046] Obtaining premixed gas with stable flow rate in the premix control module further includes using a premixing device to adjust the mixing ratio of low calorific value gas with stable pressure and air through multivariable coordinated control according to the filtered inlet pressure signal and methane content ratio parameter, so as to obtain the premixed gas.

[0047] Based on the aforementioned filtering and composition detection, this embodiment further introduces a multivariable coordinated control mechanism through a premixing device to achieve precise adjustment of the mixing ratio of gas and air. This control mechanism comprehensively considers two core variables: the real-time pressure of the inlet gas and the methane content ratio parameter. The two work together to ensure that the premixed gas generated under varying operating conditions always maintains stable flow rate and balanced composition, meeting the flameless combustion conditions. First, after the inlet pressure signal is filtered, the actual pressure value of the current gas source is output, representing the dynamic change trend of the available gas flow rate. If the pressure increases, it indicates an increase in gas supply, and the air supply needs to be appropriately increased to maintain a constant air-fuel ratio; conversely, if the pressure decreases, the air flow rate should be synchronously reduced to prevent incomplete combustion due to excessive air in the mixed gas. Second, the methane content ratio parameter is obtained from the real-time detection of methane concentration by an infrared gas analyzer and combined with a dynamic ratio database. This parameter determines the theoretical air volume ratio required for the current mixture and is the core basis for the control system to maintain calorific value balance. In multivariable coordinated control, the control unit of the premixing device receives the above two types of input information and makes real-time judgments through an embedded logic module. The control unit first evaluates the gas supply capacity corresponding to the current gas pressure, then queries the target air flow ratio corresponding to the methane ratio parameter, and then calculates the opening degree of the air valve and the gas throttling ratio to be adjusted. This calculation not only considers the individual change trends of the two parameters but also includes the interaction between them. For example, when the gas pressure slightly increases while the methane concentration decreases, the system needs to process comprehensively to avoid misjudgment causing excessive or insufficient air. The control logic adopts a hierarchical structure: the basic layer executes ratio calculation and response, giving priority to maintaining the set ratio target; the optimization layer makes smooth adjustments to sudden changes through means such as historical data tracking, disturbance estimation, and response lag compensation. The overall control process can be regarded as real-time trajectory optimization in a two-dimensional parameter space, making the mixed gas always in the region with the optimal calorific value output efficiency. After completing the adjustment of the mixing ratio, the premixing device introduces gas and air into the mixing cavity according to the set ratio, and uses an internal spoiler or static mixing element to improve the gas mixing uniformity, and finally forms a stable premixed gas suitable for flameless combustion and sends it to the subsequent backfire prevention and combustion modules.

[0048] Through the multi-variable collaborative control strategy, the present invention realizes the linkage response to the input pressure fluctuation and the change of methane concentration, and can still stably output high-consistency premixed gas under the conditions of complex load and dynamic composition change, thereby improving the thermal efficiency and safety of the entire combustion system. Compared with the single-variable or sequential control method, this control strategy can significantly reduce the response lag, ratio error and system oscillation problems, and is especially suitable for scenarios with uneven fuel quality such as oil fields, coking plants, and biogas, with higher adaptability and robustness.

[0049] Obtaining a premixed gas with stable flow rate in the premixed control module further includes driving a gas delivery pump through a variable-frequency motor, precisely adjusting the pump speed by using variable-frequency speed regulation control, combining real-time speed feedback to monitor the operating state, and adopting differential predictive control to adjust the flow rate of the premixed gas for the filtered inlet pressure signal and methane content ratio parameter. If the methane concentration is lower than the preset methane concentration threshold, the low-methane protection logic is triggered to reduce the pump output power, and a premixed gas with stable flow rate is obtained.

[0050] In this embodiment, in order to achieve fine control of the supply flow of low calorific value gas, a gas delivery pump driven by a variable frequency motor is introduced into the premixing control module, and the differential predictive control algorithm and real-time feedback mechanism are combined to improve the system's response speed and accuracy to the gas flow regulation, ensuring that the generated premixed gas is always stable and controllable. First, as the driving core, the variable frequency motor can dynamically adjust its output frequency according to the external control signal, thereby changing the speed of the gas delivery pump. The change in pump speed directly affects the gas delivery flow per unit time, and is a key factor in regulating the supply of premixed gas. The system determines the stability of the gas source based on the filtered inlet pressure signal, and determines the target gas supply based on the flow ratio parameters corresponding to the current methane concentration. In order to achieve a higher precision control response, the "differential predictive control" mechanism is introduced into the control logic. This mechanism predicts the future impact on gas demand by analyzing the changing trend of methane content and pressure signals in a short period of time. For example, if the methane concentration is detected to be slowly decreasing and the pressure value is stable, the system can predict that it may be necessary to reduce the amount of air mixture and slightly reduce the pump speed to maintain the air-fuel ratio balance in the future; conversely, if an upward trend in concentration or a rebound in pressure is detected, the pump speed will be increased in advance to improve the gas supply capacity. This type of prediction is not based on a single signal at a single moment, but a trend analysis is performed through the differential relationship between continuous data in a short period of time, and the control target is corrected in real time accordingly. In addition, the system monitors the actual operating speed of the motor in real time, compares the actual speed measured per second with the control target value, and determines whether the actuator responds normally. If there is an error exceeding the preset tolerance, the system will automatically correct the control signal or alarm prompt to prevent the accuracy of the gas flow from being affected by response lag or execution deviation. In view of the problem that low calorific value gases may have a critical lower limit of methane concentration, the system is equipped with "low methane protection logic". When the infrared analyzer detects that the methane concentration is lower than the preset minimum safety concentration threshold, such as 15% volume fraction, the system immediately triggers the protection mode, reduces the output power of the variable frequency motor to the lowest working gear, significantly reduces the gas supply rate, and prevents the occurrence of dangerous conditions such as unstable combustion, flameout or flashback of the mixed gas below the flammability boundary. At the same time, the system will start the alarm prompt to prompt the operator to check the gas source composition to ensure safe operation. The above control mechanism combines the actuator adjustment capability with the real-time feedback of multivariable signals to achieve dynamic adaptive adjustment under complex working conditions of low calorific value gas, and continuously outputs premixed gas with stable flow and controllable components to support the stable progress of the subsequent flameless combustion process.

[0051] By introducing variable frequency motors, differential predictive control and methane concentration protection mechanisms, the present invention achieves high-precision real-time control of low calorific value gas transmission flow, especially in response to methane content fluctuations or pressure disturbances, with advanced regulation capabilities, which is significantly better than traditional fixed frequency drive or single variable feedback mode. At the same time, the system has fault protection and abnormal state alarm capabilities, further improving the operational safety and intelligence level, and is suitable for deployment in industrial sites where associated gas fluctuates frequently or components change dramatically.

[0052] The premixing control module comprises a methane content detection device and a ratio regulating valve, wherein the ratio regulating valve dynamically adjusts the mixing ratio of air and low calorific value gas according to an output signal of the methane content detection device.

[0053] In this embodiment, in order to further improve the response accuracy and control flexibility of the mixing ratio of low calorific value associated gas and air, the premixing control module is equipped with a methane content detection device and a ratio control valve, and the dynamic matching of the air supply and the gas composition is realized through the linkage of the two, so as to ensure that the calorific value output of the premixed gas is always stable. The methane content detection device usually adopts the principle of non-spectral infrared sensing to perform real-time analysis on the infrared absorption characteristics of methane molecules in the low calorific value gas flow. When the mixed gas flows through the detection cavity, the methane molecules absorb infrared rays of a specific band, and the degree of absorption is proportional to its concentration. The device converts the acquired absorption signal into methane concentration data and outputs it to the main controller of the premixing control module in the form of analog voltage or digital signal. After the controller receives the methane content detection value, the first step is to compare it with the set target combustion conditions. Since methane is the main combustible component in low calorific value gas, its concentration directly affects the combustion calorific value of unit volume of gas, so the system sets the corresponding air demand according to different concentrations. If the methane content is high, the required amount of air is relatively small to prevent the formation of an overly lean mixture that leads to incomplete combustion; conversely, if the methane content is low, the air supply needs to be appropriately increased to improve combustion efficiency and fully oxidize residual hydrocarbons. The proportional control valve is driven by an electric actuator as the control core of the air supply, and its opening can be continuously adjusted according to the control signal. When the methane concentration changes, the control system calculates the required air volume change in real time and issues a control command to adjust the valve opening, thereby achieving instant adjustment of the air flow. The regulation logic generally adopts a proportional algorithm, that is, the valve opening is linearly adjusted according to the change amplitude of the methane detection signal, and hysteresis compensation and disturbance suppression mechanisms are introduced to avoid frequent fluctuations. The entire regulation process maintains a closed-loop operation mode, that is, detection, judgment, control and feedback are continuously circulated. This ensures that even under conditions where the low calorific value gas components frequently change, the composition of the premixed gas can still be kept within the acceptable range of the combustion conditions, effectively supporting the thermal field stability of the flameless combustion stage.

[0054] Through the linkage control of real-time methane concentration detection and proportional regulating valve, this embodiment realizes the intelligent dynamic adjustment of the gas mixing process, avoiding the mixing deviation or combustion instability problems caused by fixed ratio settings. This structure does not require complex modeling or database support, has a rapid response and a simple structure, and is especially suitable for small or space-constrained industrial systems. At the same time, this configuration can also be compatible with other gas concentration detection devices, with good expandability and on-site adaptability.

[0055] The flame arrester in the anti-backfire module is of metal corrugated structure or ceramic honeycomb structure, which is used to improve the backfire suppression effect. In this embodiment, in order to further enhance the safety of the system during gas transportation, especially to prevent the phenomenon of flame backflow caused by factors such as unstable combustion and instantaneous reverse pressure, a flame arrester with optimized structure is selected in the anti-backfire module. It can adopt the form of metal corrugated structure or ceramic honeycomb structure, and utilize the influence mechanism of the structure on the flame propagation path and heat conduction behavior to effectively improve the backfire suppression ability. First of all, the working principle of the metal corrugated structure flame arrester is that through the complex folded metal sheet channels inside, it forms a multi-stage flow deflection path, so that the gas is forced to continuously change the flow direction during passing through, and strong turbulence and shear effects are generated between multiple layers. When the flame enters this structure, the kinetic energy of its flame front and the gas is quickly dispersed. At the same time, due to the good heat conductivity of the metal corrugated sheet, it can quickly absorb the heat transmitted by the flame, thereby reducing the flame temperature and blocking the continuous propagation of the flame. This structure has excellent blocking performance for high-speed short-range flames and is suitable for operating environments with a high backfire frequency or dynamic loads. On the other hand, the ceramic honeycomb structure flame arrester relies on the high heat capacity and high temperature resistance of the ceramic material. The inside is arranged with porous and uniform channels, and the gas maintains a high flow rate during flowing through, but the flame is not easy to penetrate. Its working mechanism is mainly through heat dissipation. That is, when the flame front enters the honeycomb channel, due to the rapid heat absorption of the ceramic pore wall, the core temperature of the flame drops significantly, and the combustion reaction rate drops sharply, resulting in the extinction of the flame. In addition, the honeycomb structure naturally has a large specific surface area, which further enhances the heat exchange efficiency and improves the backfire blocking ability. In specific applications, the system selects the appropriate flame arrester structure form according to the gas type, pressure range and operating conditions: the metal corrugation is suitable for scenarios with high gas flow rate and rapid heat dissipation, while the ceramic honeycomb is more suitable for complex gas environments with high temperature, high humidity or corrosive impurities. Both structures can be integrated into the standard module and have the characteristics of easy replacement and maintainability, ensuring the long-term safe and reliable operation of the system.

[0056] In this embodiment, by adopting a flame arrester with optimized structure, the safety performance of the system in preventing flashback is effectively improved. The metal corrugated structure has a fast response and strong inhibition, and can adapt to complex gas flow dynamics; the ceramic honeycomb structure has high temperature resistance and long-lasting flame retardancy, and is suitable for use in harsh environments. Both of them significantly reduce the risk of equipment damage or system flameout caused by flashback, provide reliable guarantee for the stable and continuous operation of the system, and at the same time improve the overall safety level and engineering applicability of the gas system.

[0057] This low calorific value associated gas ultra-low nitrogen flameless combustion system further includes an inlet pipeline valve group 1, a gas-liquid separation device 2, a flow device 3, a pressure stabilizing device 4 and a gas main pipeline valve group 5 connected in sequence. The gas main pipeline valve group 5 is respectively connected with a gas cut-off device 8 and a gas ignition pipeline valve group 9. The gas ignition pipeline valve group 9 is connected to a flame arrester 12, the flame arrester 12 is connected to a flameless combustion device 13, the flameless combustion device 13 is connected to a boiler 14. The gas cut-off device 8 is connected in series with an electric valve 10, the electric valve 10 is connected to an auxiliary combustion pipeline valve group 11, and the auxiliary combustion pipeline valve group 11 is also connected to the flameless combustion device 13. The inlet pipeline valve group 1 is further connected to an inlet auxiliary combustion valve group 6, the inlet auxiliary combustion valve group 6 is connected to a blower 7, and the blower 7 is also connected to the auxiliary combustion pipeline valve group 11.

[0058] This embodiment conducts modular partitioning and process integration design on the system structure, enabling each component to have clear functions and cooperate efficiently, and achieving safe combustion, stable heat supply, and rapid response control for abnormal states. During the system startup phase, low-calorie gas first enters the system through the inlet pipeline valve group 1. This valve group has functions of switch control, pressure detection, and leakage protection, and is the first control checkpoint for gas to enter the system. The gas then enters the vapor-liquid separation device 2, which preliminarily purifies the raw gas, removing liquid impurities such as entrained moisture and oil mist, ensuring a pure and dry gas source, and being beneficial to improving subsequent combustion efficiency and safety. The gas after separation treatment flows into the flow device 3, which is equipped with a high-precision gas mass flowmeter to monitor the gas throughput in real time and feed the data back to the main control system for calculating the gas-air ratio and adjusting the combustion control parameters. Subsequently, the gas enters the pressure stabilizing device 4, which mainly regulates and buffers the fluctuations in the supply gas pressure, enabling the backend combustion device to receive gas with a stable pressure and ensuring the continuity and consistency of the combustion reaction. The gas after pressure stabilizing treatment enters the gas main pipeline valve group 5. This valve group is a system shunt node, one path leading to the gas cut-off device 8 and the other path leading to the gas ignition pipeline valve group 9. During the system startup phase, the ignition valve group is preferentially opened, and the low-calorie gas enters the flame arrester 12 through this path and is sent to the flameless combustion device 13 for pre-combustion. The heat generated by the combustion is conducted to the boiler 14 for heating water or steam output. When the combustion is stable, the system automatically opens the main gas path. The gas cut-off device and the subsequent electric valve 10 are connected in series to form a safety logic loop for controlling the main on-off. The electric valve automatically adjusts whether to open the main gas path according to the control system instruction, playing a role of rapid response protection. The electric valve is connected to the combustion-supporting pipeline valve group 11 at the back. This valve group converges the main gas flow and the auxiliary air source. To ensure the stability of the combustion-supporting air volume supply, the inlet pipeline valve group 1 also connects to an inlet combustion-supporting valve group 6, which further connects to a fan 7. The fan, as the source of combustion-supporting air, also enters the combustion-supporting pipeline valve group 11 through the pipeline, mixes with the gas, and then enters the flameless combustion device 13 together to improve the combustion efficiency and ensure flameless stability. The entire system feeds back multiple detection signals (including gas flow, pressure, temperature, combustion state, etc.) to the central control module to achieve multi-path collaborative regulation, dynamic flow distribution, and emergency control for abnormal states, ensuring that the low-calorie gas can burn efficiently, stably, and with low emissions under various operating conditions.

[0059] This embodiment clearly partitions each key unit module, has a smooth series connection of the structure, and a tight functional connection, forming a complete closed-loop flameless combustion treatment path for low-calorie gas. This system architecture has advantages such as strong operation stability, sensitive response control, and comprehensive safety protection, and is particularly suitable for industrial sites with high water content, large component fluctuations, and unstable gas supply sources. It has strong configuration flexibility and high maintenance convenience, which helps industrial users to quickly deploy and integrate the system.

[0060] Under complex working conditions, the gas ignition pipeline can be set as an independent subsystem and an auxiliary ignition source (such as electric heating or fuel ignition) can be connected; a flow limiter or check valve can be installed between the gas main pipeline valve group 5 and the electric valve 10 to further improve safety; the fan system can adopt a variable frequency speed regulation fan to realize intelligent combustion-aiding air supply control linked with the combustion load; the entire valve group pipeline system can also adopt a modular combination design, which is convenient for maintenance, replacement and site adaptation.

[0061] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low calorific value associated gas ultra-low nitrogen flameless combustion system, characterized in that: include: The gas acquisition module acquires low calorific value gas through an inlet pipeline valve group to obtain dry low calorific value gas; The premixing control module uses multivariable coordinated control to adjust the mixing ratio of low calorific value gas and air with stable pressure to obtain premixed gas with stable flow rate; The anti-flashback module uses a flame arrester to perform anti-flashback treatment on the premixed gas with stable flow rate, uses a flow sensor to obtain the flow data of the processed premixed gas, and optimizes the gas transmission efficiency in combination with load adaptive regulation to obtain the premixed gas with anti-flashback treatment; The flameless combustion module uses a porous ceramic burner to flamelessly burn the premixed gas that has been treated with anti-flashback. The recirculation channel is used to adjust the recirculation airflow ratio based on the feedback of the combustion chamber temperature and the exhaust temperature of the flue gas, combined with dynamic power distribution, to obtain a combustion gas with a balanced thermal field. The flame detection module collects the flame state spectral characteristics in the combustion gas with thermal field equilibrium through the flame probe, obtains the combustion chamber gas temperature and flue gas exhaust temperature through the temperature sensor, obtains the premixed gas flow data of the anti-flashback treatment in combination with the flow sensor, and generates the combustion state data set through control signal smoothing processing; The stable output module generates a first control signal, uses the first control signal to adjust the ceramic pore airflow distribution of the porous ceramic burner, and optimizes the operating parameters in combination with the motor temperature rise monitoring and fault diagnosis signals. If the flow data and the combustion chamber temperature meet the preset deviation threshold setting, a second control signal is generated, and the burner parameters are locked through the second control signal to obtain a stable combustion output.

2. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 1, characterized in that: The gas acquisition module uses a gas-liquid separation device to separate liquid impurities in the gas to obtain dry low calorific value gas.

3. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 1, characterized in that: The method of obtaining the premixed gas with a stable flow rate in the premixing control module also includes continuously collecting the inlet pressure data of the dry low calorific value gas through a high-precision pressure sensor, and processing the pressure signal using a low-pass filtering algorithm to obtain a filtered inlet pressure signal.

4. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 3 is characterized in that: The premixing control module obtains the premixed gas with stable flow rate, and also includes performing pressure stabilization processing on the dry low calorific value gas through a pressure stabilization device, using proportional gain adjustment to generate a control output amplitude for the pressure deviation in the filtered inlet pressure signal, and combining an integral time constant to eliminate steady-state errors to obtain low calorific value gas with stable pressure.

5. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 4, characterized in that: Obtaining the premixed gas with a stable flow rate in the premixing control module also includes detecting the methane concentration in the low calorific value gas with a stable pressure in real time through an infrared gas analyzer, querying a pre-established dynamic proportioning database, obtaining the flow proportioning coefficient corresponding to the methane content, and determining the methane content proportioning parameters.

6. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 5, characterized in that: Obtaining the premixed gas with a stable flow rate in the premixing control module also includes obtaining the premixed gas by adjusting the mixing ratio of the low calorific value gas with stable pressure and air by using multivariable coordinated control according to the filtered inlet pressure signal and the methane content ratio parameter through the premixing device.

7. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 6, characterized in that: The method of obtaining a premixed gas with a stable flow rate in the premixing control module also includes driving a gas delivery pump through a variable frequency motor, using variable frequency speed control to accurately adjust the pump speed, combining real-time speed feedback to monitor the operating status, and using differential predictive control to adjust the premixed gas flow rate based on the filtered inlet pressure signal and methane content ratio parameters. If the methane concentration is lower than a preset methane concentration threshold, the low methane protection logic is triggered to reduce the pump output power to obtain a premixed gas with a stable flow rate.

8. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 1, characterized in that: The premixing control module comprises a methane content detection device and a ratio regulating valve, and the ratio regulating valve dynamically adjusts the mixing ratio of air and low calorific value gas according to the output signal of the methane content detection device.

9. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 1, characterized in that: The flame arrester in the anti-flashback module is a metal corrugated structure or a ceramic honeycomb structure, which is used to improve the flashback suppression effect.

10. The ultra-low nitrogen flameless combustion system for low calorific value associated gas according to claim 1, characterized in that: The invention also comprises an inlet pipeline valve group (1), a vapor-liquid separation device (2), a flow device (3), a pressure stabilizing device (4) and a gas main pipeline valve group (5) which are connected in sequence. The gas main pipeline valve group (5) is respectively connected to a gas cut-off device (8) and a gas ignition pipeline valve group (9). The gas ignition pipeline valve group (9) is connected to a flame arrester (12). The flame arrester (12) is connected to a flameless combustion device (13). The flameless combustion device (13) is connected to a boiler (14). The gas cut-off device (8) is connected in series with an electric valve (10). The electric valve (10) is connected to a combustion-supporting pipeline valve group (11). The combustion-supporting pipeline valve group (11) is also connected to the flameless combustion device (13). The inlet pipeline valve group (1) is also connected to an inlet combustion-supporting valve group (6). The inlet combustion-supporting valve group (6) is connected to a fan (7). The fan (7) is also connected to the combustion-supporting pipeline valve group (11).

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