Method and device for detecting multi-component gas in tail gas in alcohol-based fuel combustion process

Abstract

The invention discloses a method and a device for detecting multi-component gas in tail gas in an alcohol-based fuel combustion process. The method comprises the following steps: sequentially performing alkali liquor soaking, acid liquor coarsening and ultrasonic cleaning on a ceramic tube, preparing double-component slurry, and then performing dispensing coating and sintering in an oxygen atmosphere to obtain a double-coating gas sensitive sensor; a gas sensor is connected with a single chip microcomputer and a signal processing circuit, a display module and a reset circuit are configured, and a temperature control heating system is constructed to achieve temperature adjustment of the sensor. Acquiring initial parameters of the gas sensor, establishing a kinetic equation, introducing a compensation function and compensation parameters, and implementing signal sampling processing to obtain a gas concentration value; a platinum resistor temperature sensor is adopted to collect temperature in real time, a baseline drift algorithm and a correction model are established, and zero point and range calibration is carried out regularly through standard gas. Through the scheme of the invention, cross sensitivity and baseline drift can be suppressed, and the detection accuracy is improved.

Description

Technical Field

[0001] The present application relates to the field of measurement, and in particular to a method and device for detecting multi-component gases in tail gas during the combustion of alcohol-based fuel. Background Art

[0002] With the increasing demand for environmental protection and the continuous optimization of energy structure, alcohol-based fuel is widely used in industry and transportation field because of its clean and efficient characteristics. However, alcohol-based fuel still produces harmful gases including carbon monoxide and nitrogen dioxide during combustion, and the emission of these gases not only affects the quality of atmospheric environment, but also may endanger human health. Therefore, it is of great significance to monitor the tail gas of alcohol-based fuel in real time and accurately. In the prior art, the tail gas monitoring of alcohol-based fuel mainly adopts semiconductor metal oxide gas sensor to detect. This type of sensor realizes the detection of target gas by loading metal oxide materials with gas-sensitive properties on ceramic substrate (such as aluminum oxide, zirconium oxide, etc.). Among them, the most common sensitive materials include tin dioxide, tungsten trioxide, zinc oxide, etc. These materials have the advantages of simple preparation process, low cost and high response sensitivity.

[0003] However, in the actual application of the existing alcohol-based fuel exhaust monitoring sensor, carbon monoxide and nitrogen dioxide often exist simultaneously in the alcohol-based fuel exhaust. Since there are opposite electron transfer directions between the two gases and the sensor material, that is, carbon monoxide provides electrons to the material through oxidation reaction, and nitrogen dioxide obtains electrons from the material through reduction reaction, this competitive electron gain and loss process will cause the signal to interfere with each other. Specifically, when carbon monoxide and nitrogen dioxide exist at the same time, the electrical signal output by the sensor cannot accurately reflect the actual concentration of each component, reducing the accuracy and reliability of the detection. In addition, during continuous operation, the sensor needs to maintain a high operating temperature (usually in the range of 200-400°C) to ensure the progress of the gas-sensitive reaction. However, under high temperature conditions, the oxygen adsorption-desorption process on the surface of the sensor material is in a dynamic equilibrium state. Slight fluctuations in ambient temperature can cause this balance to change, causing changes in the intrinsic conductivity of the material. This phenomenon is manifested as the zero-point resistance value of the sensor (i.e., the reference resistance when there is no target gas) drifting over time, seriously affecting the repeatability and stability of the measurement.

[0004] Therefore, there is an urgent need for a technical solution that can suppress cross-sensitivity and baseline drift and improve detection accuracy. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the embodiment of the present application provides a method and device for detecting multi-component gases in tail gas during the combustion of alcohol-based fuels. The present application solves the technical problems of cross sensitivity and baseline drift in the prior art.

[0006] The embodiment of the present application provides a method for detecting multi-component gases in exhaust during the combustion of alcohol-based fuels, comprising: sequentially soaking a ceramic tube in alkaline solution, roughening it with acid solution, and ultrasonically cleaning it, preparing a two-component slurry and then coating it by dispensing, and sintering it in an oxygen atmosphere to obtain a double-coated gas sensor; connecting the gas sensor to a single-chip microcomputer and a signal processing circuit, configuring a display module and a reset circuit, and constructing a temperature control and heating system to achieve sensor temperature regulation; obtaining initial parameters of the gas sensor to establish a kinetic equation, introducing a compensation function and compensation parameters, and performing signal sampling processing to obtain a gas concentration value; using a platinum resistance temperature sensor to collect temperature in real time, establishing a baseline drift algorithm and a correction model, and regularly performing zero point and range calibration using standard gas.

[0007] In a possible implementation, the ceramic tube is sequentially soaked in alkali solution, roughened in acid solution and ultrasonically cleaned, a two-component slurry is prepared, and then coated by dispensing, and sintered in an oxygen atmosphere to obtain a double-coated gas sensor, including: soaking the ceramic tube in a sodium hydroxide solution with a preset concentration to remove surface oil, and then rinsing it with deionized water to neutrality; soaking the ceramic tube in a hydrochloric acid solution with a preset concentration to roughen the surface and increase the coating bonding strength; using anhydrous ethanol to ultrasonically clean the ceramic tube in an ultrasonic cleaner, and then placing it in a drying oven for drying; mixing barium titanate, nano tin oxide, indium oxide and silver oxide according to a mass ratio, adding anhydrous ethanol and a dispersant, and then ball milling; mixing nano tin oxide, nano tungsten oxide, platinum and ruthenium according to a mass ratio, adding anhydrous ethanol and a dispersant, and then ball milling; using a precision dispensing machine to coat the two slurries on both ends of the ceramic tube, respectively, and pre-drying after three intervals of coating; placing the coating sample in a tubular furnace to heat up, passing an oxygen atmosphere to sinter, and then cooling to obtain a double-coated gas sensor.

[0008] In a possible implementation, the gas sensor is connected to a single-chip microcomputer and a signal processing circuit, a display module and a reset circuit are configured, and a temperature control heating system is constructed to achieve sensor temperature adjustment, including: connecting the gas sensor to the single-chip microcomputer, using a built-in analog-to-digital converter to collect the sensor resistance signal; using a Wheatstone bridge structure to construct a signal conditioning circuit, and using an operational amplifier to construct a signal amplification circuit; using a display module to connect to the single-chip microcomputer through a communication interface, and configuring a reset circuit; using pulse width modulation to construct a sensor heating circuit, and achieving temperature control through a closed-loop control algorithm; using a platinum resistor in combination with a temperature conversion module for temperature acquisition, and using a platinum wire as a heating wire for winding.

[0009] In one possible implementation, the initial parameters of the gas sensor are obtained to establish a kinetic equation, a compensation function and compensation parameters are introduced, and signal sampling processing is performed to obtain a gas concentration value, including: obtaining the initial resistance value, sensitivity coefficient, response rate constant and cross-sensitivity coefficient of the sensor; establishing a kinetic equation for the adsorption-desorption process of gas molecules on the sensor surface; introducing a nonlinear compensation function and obtaining compensation parameters through a least squares method; and performing signal acquisition and processing to obtain a gas concentration value based on the kinetic equation and compensation parameters.

[0010] In one possible implementation, a platinum resistance temperature sensor is used to collect temperature in real time, a baseline drift algorithm and a correction model are established, and zero point and range calibration are performed regularly using standard gas, including: using a four-wire platinum resistance temperature sensor in conjunction with a temperature conversion module to collect temperature data; establishing a baseline drift detection algorithm to obtain the temperature coefficient and the standard operating temperature; establishing a periodic baseline correction model to determine the dynamic attenuation coefficient; performing zero point calibration by cutting off the sampling gas path and introducing clean air; and performing range calibration using standard gas to update the sensitivity coefficient.

[0011] In a possible implementation, a nonlinear compensation function is introduced and compensation parameters are obtained by a least square method, including: ,in, represents the compensation parameter, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, Represents the hyperbolic sine function.

[0012] In a possible implementation, signal acquisition and processing are performed to obtain a gas concentration value based on a kinetic equation and a compensation parameter, including: ,in, Represents the output signal, Indicates the resistance change value, Indicates compensation parameters.

[0013] In a possible implementation, establishing a periodic baseline correction model includes: ,in, Indicates the corrected resistance value, represents the original resistance value, Indicates the baseline drift value, represents the dynamic attenuation coefficient, Indicates the current time. Indicates the time point of the last calibration.

[0014] An embodiment of the present application also provides a multi-component gas detection device for exhaust during the combustion of alcohol-based fuel, comprising: a processor, a memory, and a system bus; wherein the processor and the memory are connected via the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, enable the processor to execute the method described in any one of the above embodiments.

[0015] In a method and device for detecting multi-component gases in exhaust gas during the combustion of alcohol-based fuels as provided above, the embodiment of the present application can suppress the cross-sensitivity effect through a nonlinear compensation method, thereby more accurately detecting the concentrations of carbon monoxide and nitrogen dioxide in the exhaust gas, and avoiding the signal distortion problem caused by the competition of electron gain and loss reactions. Further, in some embodiments, a baseline drift detection algorithm and a periodic correction model are established, and the correction parameters are dynamically adjusted by real-time monitoring of temperature changes, and baseline correction is performed periodically during the detection process, which can suppress baseline drift, improve the repeatability and stability of the measurement, and thus improve the measurement accuracy. By using precision dispensing coating and high-temperature sintering process to prepare a double-coated gas sensor, the bonding strength between the coating and the ceramic tube is enhanced, and the stability and service life of the sensor are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic flow chart of a method for detecting multi-component gases in exhaust during the combustion of alcohol-based fuels provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure unless otherwise specifically stated.

[0019] Those skilled in the art can understand that the terms "first", "second" and the like in the embodiments of the present disclosure are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor represent the necessary logical order between them. It should also be understood that in the embodiments of the present disclosure, "multiple" can refer to two or more, and "at least one" can refer to one, two or more. It should also be understood that for any component, data or structure mentioned in the embodiments of the present disclosure, in the absence of explicit limitation or contrary revelation given in the context, it can generally be understood as one or more. In addition, the term "and / or" in the present disclosure is only a description of the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present disclosure generally indicates that the associated objects before and after are an "or" relationship. It should also be understood that the description of each embodiment in the present disclosure emphasizes the differences between the embodiments, and the same or similar parts can refer to each other. For the sake of brevity, they will not be repeated one by one.

[0020] At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use. The techniques, methods and devices known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and devices should be considered part of the specification. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] Figure 1 A schematic flow chart of a multi-component gas detection method for real-time monitoring of exhaust gas during the combustion of alcohol-based fuels provided in an embodiment of the present application.

[0023] It should be noted that the current alcohol-based fuel exhaust monitoring mainly uses a bimetallic oxide composite sensor method, which achieves detection by loading different sensitive materials on a ceramic substrate. , The common practice is to , Metal oxides such as ferrite are used as basic materials, and the sensitivity and selectivity are improved by doping with precious metals or other metal oxides.

[0024] Since alcohol-based fuel exhaust and There is a competition mechanism for electron gain and loss reactions, and when two gases exist at the same time, cross-sensitivity problems will occur. Specifically, Oxidation reaction with the sensor surface releases electrons, The sensor surface undergoes a reduction reaction to obtain electrons, and the mutual interference of this electron transfer causes distortion of the sensor signal. At the same time, existing sensors have baseline drift problems under high temperature working conditions, which is mainly manifested as the zero-point resistance of the sensor changing over time. This drift is caused by the dynamic changes of oxygen species adsorbed on the material surface due to temperature fluctuations, which makes the sensor output signal unstable and affects the measurement accuracy.

[0025] In order to solve the problems of cross sensitivity and baseline drift, the present invention discloses a multi-component gas detection method for real-time monitoring of tail gas during the combustion of alcohol-based fuel. and Real-time monitoring of the exhaust gas is achieved by loading carbon monoxide sensor coating and nitrogen dioxide sensor coating on both ends of the ceramic tube, combining the dual-channel signal processing method of nonlinear compensation and the baseline correction method of adaptive temperature compensation. (1.0~300ppm) and (2.0~100ppm) accurate detection.

[0026] Specific implementation as Figure 1 As shown, in step S101, the ceramic tube is soaked in alkali solution, roughened in acid solution and ultrasonically cleaned in sequence, and a two-component slurry is prepared and then coated by dispensing, and sintered in an oxygen atmosphere to obtain a double-coated gas sensor. The process includes: soaking the ceramic tube in a sodium hydroxide solution with a preset concentration to remove surface oil, and then rinsing it with deionized water until it is neutral; soaking the ceramic tube in a hydrochloric acid solution with a preset concentration to roughen the surface and increase the bonding strength of the coating; ultrasonically cleaning the ceramic tube in an ultrasonic cleaning instrument with anhydrous ethanol, and then placing it in a drying oven for drying; mixing barium titanate oxide, nano-tin oxide, indium oxide and silver oxide according to a mass ratio, adding anhydrous ethanol and a dispersant, and then ball milling; mixing nano-tin oxide, nano-tungsten oxide, platinum and ruthenium according to a mass ratio, adding anhydrous ethanol and a dispersant, and then ball milling; using a precision dispensing machine to coat the two slurries on both ends of the ceramic tube, and pre-drying after three intervals of coating; placing the coating sample in a tubular furnace to heat up, passing an oxygen atmosphere to sinter, and then cooling to obtain a double-coated gas sensor.

[0027] In one embodiment, a ceramic tube substrate is first prepared, using a high-purity (99.9%) alumina ceramic tube with a tube diameter of 3.5 mm, a wall thickness of 0.4 mm, and a length of 12 mm. The surface pretreatment of the ceramic tube adopts a three-step method: first, soak it in a 10% sodium hydroxide solution for 15 minutes to remove surface oil stains, then rinse it with deionized water until it is neutral; then soak it in a 5% hydrochloric acid solution for 10 minutes to roughen the surface and increase the bonding strength of the coating; finally, use anhydrous ethanol to ultrasonically clean it in a 40kHz ultrasonic cleaner for 15 minutes, and dry it in an 80°C drying oven for 2 hours.

[0028] The carbon monoxide sensor coating was prepared by weighing the following ratio: ,nanometer , and Among them, nano The particle size should be controlled within the range of 30-50nm, and the specific surface area should be greater than 35m² / g. The above raw materials are mixed with an appropriate amount of anhydrous ethanol (alcohol-to-material ratio is 3:1) and a dispersant (accounting for 0.8% of the total mass of the powder), and ball milled in a planetary ball mill at 300rpm for 4h, with a ball-to-material ratio of 4:1, and zirconia ball milling balls are used. The milled slurry is filtered through a 100-mesh screen, left to stand for 2h to exhaust, and then used.

[0029] The nitrogen dioxide sensor coating is weighed with nanoparticles in a mass ratio of 8:2:1.3:1. ,nanometer , and Among them, nano The particle size is controlled at 40-60nm, and the specific surface area is greater than 30m² / g. The slurry is prepared by the same ball milling process as the carbon monoxide sensor coating. The viscosity of the two coating slurries should be controlled at 2800±200mPa·s (measured at 25℃).

[0030] Use a dispensing machine to coat the two slurries on both ends of the ceramic tube. The dispensing pressure is controlled at 0.24MPa, the dispensing rate is 0.8mm / s, the single coating thickness is 7-8μm, and three coatings are performed at intervals of 5min. The final coating thickness is controlled at 22±2μm. After the coating is completed, pre-dry it at 60℃ for 30min. Place the coated sample in a tubular furnace, heat it to 450℃ at a heating rate of 5℃ / min, introduce oxygen atmosphere (flow rate 0.5L / min), sinter at a constant temperature for 2h, and then cool it to room temperature at 3℃ / min to obtain a double-coated gas sensor.

[0031] The above step S101 adopts a double coating structure, which improves the response speed and sensitivity of the sensor to the target gas, and can quickly and accurately detect harmful gases in the exhaust gas; by optimizing the sensor material and coating ratio, the gas-sensitive characteristics of the sensor are enhanced, so that the sensor can still maintain good detection performance within a lower concentration range.

[0032] At step S102, the gas sensor is connected to the single-chip microcomputer and the signal processing circuit, a display module and a reset circuit are configured, and a temperature control heating system is constructed to achieve sensor temperature adjustment. This includes: connecting the gas sensor to the single-chip microcomputer, using a built-in analog-to-digital converter to collect sensor resistance signals; using a Wheatstone bridge structure to construct a signal conditioning circuit, and using an operational amplifier to construct a signal amplification circuit; using a display module to connect to the single-chip microcomputer through a communication interface, and configuring a reset circuit; using pulse width modulation to construct a sensor heating circuit, and achieving temperature control through a closed-loop control algorithm; using a platinum resistor in conjunction with a temperature conversion module for temperature acquisition, and using a platinum wire as a heating wire for winding.

[0033] The above step S102 constructs a temperature control heating system, and uses a closed-loop control algorithm to achieve precise temperature control, ensuring that the sensor operates at an optimal operating temperature, thereby reducing the impact of temperature fluctuations on the measurement results.

[0034] In one embodiment, the prepared gas sensor is connected to the STM32F103C8T6 single-chip microcomputer, and the sensor resistance signal is collected by a built-in 12-bit AD converter, and the sampling rate is set to 10Hz. The signal conditioning circuit adopts a Wheatstone bridge structure, the excitation voltage is 3.3V, and the high-precision operational amplifier AD8628 is used to construct the signal amplification circuit, and the gain is set to 82 times. The display module uses a 0.96-inch OLED screen (model SSD1306) with a resolution of 128×64, and communicates with the single-chip microcomputer through an IIC interface. The reset circuit adopts RC delay reset, using a 10kΩ resistor and a 4.7μF capacitor, and the reset time is about 47ms.

[0035] The sensor heating circuit adopts PWM modulation, with an operating voltage of 5V and a PWM frequency of 20kHz. The temperature is stabilized at 225±2℃ through the PI closed-loop control algorithm. The control parameters Kp=0.68, Ki=0.023, and the sampling period is 100ms. The temperature acquisition uses a PT100 platinum resistor (grade A), combined with a MAX31865 temperature conversion module, with a temperature measurement accuracy of ±0.1℃. The heating wire uses platinum wire with a resistance value of 5.2Ω (25℃), 12 turns, and a turn spacing of 0.4mm.

[0036] In step S103, the initial parameters of the gas sensor are obtained to establish a kinetic equation, a compensation function and compensation parameters are introduced, and signal sampling processing is performed to obtain a gas concentration value.

[0037] Furthermore, it includes: obtaining the initial resistance value, sensitivity coefficient, response rate constant and cross-sensitivity coefficient of the sensor; establishing a kinetic equation for the adsorption-desorption process of gas molecules on the sensor surface; introducing a nonlinear compensation function and obtaining compensation parameters through the least squares method; performing signal acquisition and processing to obtain the gas concentration value based on the kinetic equation and compensation parameters.

[0038] Among them, a nonlinear compensation function is introduced, and the compensation parameters are obtained by the least square method, including: ,in, represents the compensation parameter, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, Represents the hyperbolic sine function.

[0039] Among them, signal acquisition and processing are performed to obtain gas concentration values ​​based on kinetic equations and compensation parameters, including: ,in, Represents the output signal, Indicates the resistance change value, Indicates compensation parameters.

[0040] Specifically, in one implementation scenario, when the exhaust gas enters the detection chamber, CO and NO2 molecules undergo electron transfer reactions with the sensor surface. At an operating temperature of 225°C, the adsorption-desorption process of gas molecules on the sensor surface follows pseudo-first-order reaction kinetics. The resistance change of the sensor satisfies the following kinetic equation: , where the initial parameters are obtained by standard gas calibration: : The initial resistance of the sensor is 23.6kΩ. The initial resistance of the sensor is 31.8kΩ (measured at 25℃ and 50%RH); = 0.0427, = 0.0683 (sensitivity coefficient calibrated using 50ppm standard gas); = 0.0234s -1 , = 0.0198s -1(response rate constant, determined using the step response method); = 0.00876 (cross-sensitivity coefficient, at 25ppm +10ppm Calibration in mixed atmosphere); is the response time (s); , is the gas concentration (ppm).

[0041] In order to eliminate the cross-sensitivity effect, a nonlinear compensation function is introduced: , the compensation parameters are obtained by least squares optimization: =0.0156, = 0.0234 (compensation weight coefficient), = 0.00432, = 0.00567 (non-linear modulation factor).

[0042] The final sensor output signal is expressed as: The system completes a complete signal acquisition and processing process every 0.5s: first, 16 AD samples are taken to get the average value to reduce random noise; then the sampled value is converted into a resistance value through a calibration curve; then it is substituted into the kinetic equation to calculate the initial value of the gas concentration; finally, the nonlinear compensation function is used to correct it to obtain the final concentration value.

[0043] In step S104, a platinum resistance temperature sensor is used to collect temperature in real time, a baseline drift algorithm and a correction model are established, and zero point and range calibration are performed regularly using standard gas.

[0044] Furthermore, it includes: using a four-wire platinum resistance temperature sensor in conjunction with a temperature conversion module to collect temperature data; establishing a baseline drift detection algorithm to obtain the temperature coefficient and the standard operating temperature; establishing a periodic baseline correction model to determine the dynamic attenuation coefficient; performing zero point calibration by cutting off the sampling gas path and introducing clean air; using standard gas to perform range calibration and update the sensitivity coefficient.

[0045] Among them, a periodic baseline correction model is established, including: ,in, Indicates the corrected resistance value, represents the original resistance value, Indicates the baseline drift value, represents the dynamic attenuation coefficient, Indicates the current time. Indicates the time point of the last calibration.

[0046] Specifically, in one implementation scenario, in order to solve the baseline drift problem, the system collects temperature data every 100ms for real-time compensation. A PT100 platinum resistance temperature sensor can be used, and the four-wire connection method can eliminate the influence of lead resistance. In combination with the MAX31865 temperature conversion module, the temperature measurement accuracy is ±0.1°C. The baseline drift detection algorithm is: , where the parameters are set to: : Sensor 23.6kΩ, Sensor 31.8kΩ (calibrated value at 25℃); = -0.00432 K -1 (Temperature coefficient, calibrated within the range of 180-260℃); =225℃ (standard operating temperature); It is the real-time temperature with a sampling frequency of 10Hz.

[0047] Next, construct the periodic baseline correction model: , where the dynamic attenuation coefficient is: , = 0.0167s -1 (initial attenuation coefficient, determined according to the sensor aging characteristics); = 2.34 (temperature change rate influence factor, calibrated by temperature cycle experiment); The time point of the last calibration; is the temperature change rate, calculated using 5-point smooth differential.

[0048] The system performs an automatic zero calibration at regular intervals. For example, the sampling gas line is cut off every 30 minutes, and the baseline value is collected after the clean air is introduced for 3 minutes. If the baseline deviation exceeds ±2%, the value is updated. Use standard gas (50ppm) every 2 hours +20ppm ) to perform range calibration and update the sensitivity coefficient according to the deviation between the measured value and the standard value.

[0049] Next, the embodiment of the present application is further explained by taking the exhaust gas monitoring of a methanol fuel power generation unit as an example.

[0050] The double-coated gas sensor is installed on the sampling pipeline. The sampling pipeline uses a 316L stainless steel pipe with an inner diameter of 8mm, 1.2m away from the exhaust port. The outside of the pipeline is wrapped with a 50mm thick glass wool insulation layer, and the inner wall is gold-plated to reduce gas adsorption. A micro-diaphragm air pump is used to extract the exhaust gas, and the flow rate is controlled at 0.8L / min. The sampling pipeline is maintained at a 45° inclination to prevent condensed water from flowing back. The gas system is equipped with a particle filter (precision 0.3μm) and a condensed water separator.

[0051] The front end of the sampling system is equipped with a heating pipe section with a temperature of 180°C and a length of 0.3m to prevent condensation of water vapor. Standard gas (50ppm) is used every 2 hours. +20ppm , relative uncertainty ≤ 2%) for calibration. The calibration gas is switched to intake through a three-way valve, and the flow rate is consistent with the sampling gas flow rate. The system has an automatic backflush function, and backflush cleaning is performed at a fixed time every day (2 am).

[0052] In actual testing, the system collects data every 0.5s. The sampled data is filtered through a five-point median filter to eliminate accidental interference. When the concentration suddenly rises (>150ppm) for more than 3 seconds, the system automatically triggers an audible and visual alarm. The measured data is transmitted to the host computer via the RS485 interface (baud rate 9600, using Modbus-RTU protocol), and the concentration change trend and temperature status are displayed in real time.

[0053] Based on the results of 30 consecutive days of field testing, this method has the following performance characteristics at an operating temperature of 225°C: Detection accuracy: ±3% (1.0~300ppm range), Detection accuracy: ±4% (2.0-100ppm range), response time (T90) less than 12s, repeatability error ≤2.5%, zero drift ≤±2%FS / week, range drift: ≤±3%FS / month, ambient temperature effect: ≤±0.2%FS / ℃ (5-40℃ range), ambient humidity effect: ≤±0.3%FS / 10%RH (20%-85%RH range) In addition, it should be noted that during the sensor preparation process, the slurry ball milling time should not exceed the specified value to avoid excessive agglomeration of the powder and affect the gas sensing performance. The slurry after ball milling should be screened and the viscosity checked in time. The sintering heating rate is strictly controlled within 5℃ / min to avoid cracking of the coating due to thermal stress. A sufficient flow of oxygen must be introduced into the sintering atmosphere to ensure that the metal oxide is fully oxidized. The operating temperature fluctuation must be controlled within the range of ±2℃. Too high temperature will accelerate the aging of the sensor, and too low temperature will reduce the response speed. The heating circuit should be powered by an independent power supply to avoid sharing the ground with the signal acquisition circuit. The sampling pipeline needs to be cleaned once a week, the sealing should be checked and dust should be removed. The filter element should be replaced every 1 to 3 months according to the use environment. The condensate separator should be drained every day. When the ambient humidity exceeds 85%RH, a silica gel drying tube needs to be installed for pretreatment. When the silica gel changes color by more than 2 / 3, it should be replaced in time. The sensor should be placed in a dry environment when the system is out of use for a long time. The standard gas cylinder should not be used for more than 1 month to avoid changes in concentration that affect the calibration accuracy. When replacing a cylinder, an overlapping period of more than 30 minutes should be reserved for cross-checking. When the system is used for the first time or reactivated after a long period of inactivity, it needs to be preheated for at least 4 hours. During this period, standard gas calibration is performed every 30 minutes until the indication is stable. Check the data communication quality regularly. The RS485 bus cable can use a shielded twisted pair cable with a total length of no more than 500m, and a 120Ω terminal resistor is added at both ends.

[0054] In summary, the embodiments of the present application are based on the principle of electron transfer dynamics between gas molecules and sensor surfaces. By introducing a hyperbolic sine function as a nonlinear compensation term, the electron competition effect between different gas molecules can be accurately described. The sinh term in the compensation function can simulate the saturation effect of electron transfer, while the weight coefficient and modulation factor are used to balance the contribution of different gases.

[0055] On the other hand, based on the temperature-resistance characteristics of the sensor, a baseline drift detection algorithm and a periodic correction model are established to achieve real-time compensation for baseline drift caused by temperature fluctuations. The dynamically adjusted attenuation coefficient can adaptively adjust the correction intensity according to the temperature change rate to ensure the accuracy of the correction.

[0056] The cooperation between nonlinear compensation and adaptive temperature compensation not only solves the accuracy problem of gas cross interference, but also ensures the stability of sensor signals and realizes reliable real-time monitoring.

[0057] Furthermore, an embodiment of the present application also provides a multi-component gas detection device for real-time monitoring of exhaust gas during the combustion of alcohol-based fuel, comprising: a processor, a memory, and a system bus; the processor and the memory are connected via the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, enable the processor to execute any of the above methods.

[0058] Furthermore, an embodiment of the present application also provides a computer program product, which, when executed on a terminal device, enables the terminal device to execute any one of the above-mentioned processing methods.

[0059] It can be known from the description of the above implementation mode that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., including several instructions for enabling a computer device (which can be a personal computer, a server, or a network communication device such as a media gateway, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0060] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0061] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0062] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting multi-component gases in tail gas during the combustion of alcohol-based fuels, characterized in that: include: The ceramic tube is sequentially soaked in alkali solution, roughened in acid solution and ultrasonically cleaned, a two-component slurry is prepared, and then coated by dispensing, and sintered in an oxygen atmosphere to obtain a double-coated gas sensor. Connect the gas sensor to the microcontroller and signal processing circuit, configure the display module and reset circuit, and build a temperature control and heating system to achieve sensor temperature regulation; Obtain the initial parameters of the gas sensor to establish a kinetic equation, introduce compensation functions and compensation parameters, and perform signal sampling processing to obtain the gas concentration value; A platinum resistance temperature sensor is used to collect temperature in real time, a baseline drift algorithm and correction model are established, and zero point and range calibration are performed regularly using standard gas.

2. The multi-component gas detection method according to claim 1, characterized in that: in, The ceramic tube is sequentially soaked in alkali solution, roughened in acid solution and ultrasonically cleaned, a two-component slurry is prepared, and then coated by dispensing, and sintered in an oxygen atmosphere to obtain a double-coated gas sensor, including: Soak the ceramic tube in a sodium hydroxide solution with a preset concentration to remove surface oil stains, and then rinse with deionized water until it becomes neutral; Soak the ceramic tube in a hydrochloric acid solution with a preset concentration to roughen the surface and increase the bonding strength of the coating; The ceramic tube is ultrasonically cleaned in an ultrasonic cleaner using anhydrous ethanol, and then placed in a drying oven for drying; Barium titanate oxide, nano-tin oxide, indium oxide and silver oxide are mixed according to mass ratio, and then anhydrous ethanol and a dispersant are added and ball milled; Nano-tin oxide, nano-tungsten oxide, platinum and ruthenium are mixed according to mass ratio, and then anhydrous ethanol and a dispersant are added and ball milled; Use a precision dispensing machine to apply the two slurries to both ends of the ceramic tube respectively, apply them three times at intervals and then pre-dry them; The coating sample is placed in a tube furnace to increase the temperature, introduced into an oxygen atmosphere for sintering, and then cooled to obtain a double-coating gas sensor.

3. The multi-component gas detection method according to claim 1, characterized in that: in, Connect the gas sensor to the microcontroller and signal processing circuit, configure the display module and reset circuit, and build a temperature control and heating system to adjust the sensor temperature, including: Connect the gas sensor to the microcontroller and use the built-in analog-to-digital converter to collect the sensor resistance signal; The signal conditioning circuit is constructed by using a Wheatstone bridge structure, and the signal amplification circuit is constructed by using an operational amplifier; The display module is connected to the single-chip microcomputer through a communication interface, and a reset circuit is configured; The sensor heating circuit is constructed by pulse width modulation, and temperature control is achieved through a closed-loop control algorithm; A platinum resistor is used in conjunction with a temperature conversion module for temperature acquisition, and a platinum wire is used as the heating wire for winding.

4. The multi-component gas detection method according to claim 1, characterized in that: in, Obtain the initial parameters of the gas sensor to establish the kinetic equation, introduce the compensation function and compensation parameters, and implement signal sampling processing to obtain the gas concentration value, including: Obtain the initial resistance value, sensitivity coefficient, response rate constant and cross-sensitivity coefficient of the sensor; Establish the kinetic equation of the adsorption-desorption process of gas molecules on the sensor surface; A nonlinear compensation function is introduced and the compensation parameters are obtained by the least square method; Signal acquisition and processing are performed to obtain gas concentration values ​​based on kinetic equations and compensation parameters.

5. The multi-component gas detection method according to claim 1, characterized in that: in, Use platinum resistance temperature sensor to collect temperature in real time, establish baseline drift algorithm and correction model, and perform zero point and span calibration regularly with standard gas, including: A four-wire platinum resistance temperature sensor is used in conjunction with a temperature conversion module to collect temperature data; Establish a baseline drift detection algorithm to obtain the temperature coefficient and standard operating temperature; Establish a periodic baseline correction model and determine the dynamic attenuation coefficient; Zero point calibration is performed by cutting off the sampling gas line and introducing clean air; Use standard gas to calibrate the range and update the sensitivity coefficient.

6. The multi-component gas detection method according to claim 4, characterized in that: in, A nonlinear compensation function is introduced and the compensation parameters are obtained by the least squares method, including: ， in, represents the compensation parameter, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, express Compensation weight coefficient, express Nonlinear modulation factor, express Gas concentration, Represents the hyperbolic sine function.

7. The multi-component gas detection method according to claim 4, characterized in that: in, Perform signal acquisition and processing to obtain gas concentration values ​​based on kinetic equations and compensation parameters, including: ， in, Represents the output signal, Indicates the resistance change value, Indicates compensation parameters.

8. The multi-component gas detection method according to claim 5, characterized in that: in, Establish a periodic baseline correction model, including: ， in, Indicates the corrected resistance value, represents the original resistance value, Indicates the baseline drift value, represents the dynamic attenuation coefficient, Indicates the current time. Indicates the time point of the last calibration.

9. A multi-component gas detection device for tail gas during the combustion of alcohol-based fuel, characterized in that: include: A processor, a memory, and a system bus; wherein the processor and the memory are connected via the system bus; The memory is used to store one or more programs, wherein the one or more programs include instructions, and when the instructions are executed by the processor, the processor executes the method according to any one of claims 1 to 8.

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