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

Abstract

The present application discloses a method and device for detecting multi-component gases in the tail gas during the combustion process of alcohol-based fuels. The method includes: successively soaking a ceramic tube in an alkali solution, coarsening it with an acid solution, and ultrasonically cleaning it. After preparing a two-component slurry, it is coated by dispensing, and a double-coated gas sensor is obtained by sintering in an oxygen atmosphere; 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 heating system to realize the temperature adjustment of the sensor; obtaining the initial parameters of the gas sensor to establish a kinetic equation, introducing a compensation function and compensation parameters, and implementing signal sampling processing to obtain the gas concentration value; using a platinum resistance temperature sensor to collect the temperature in real time, establishing a baseline drift algorithm and a calibration model, and performing zero-point and range calibration regularly with calibration gases. Through the solution of the present application, cross-sensitivity and baseline drift can be suppressed, and the detection accuracy can be improved.

Description

Technical Field

[0001] This application relates to the field of measurement, and particularly to a method and device for detecting multi-component gases in the tail gas during the combustion process of alcohol-based fuels. Background Art

[0002] With the increasing requirements for environmental protection and the continuous optimization of the energy structure, alcohol-based fuels have been widely used in the industrial and transportation fields due to their clean and efficient characteristics. However, alcohol-based fuels still produce harmful gases such as carbon monoxide and nitrogen dioxide during the combustion process. The emissions of these gases not only affect the quality of the atmospheric environment but also may endanger human health. Therefore, it is of great significance to monitor the tail gas of alcohol-based fuels in real time and accurately. In the prior art, the monitoring of alcohol-based fuel tail gas mainly uses semiconductor metal oxide gas sensors for detection. Such sensors detect the target gas by loading metal oxide materials with gas-sensitive characteristics on a ceramic substrate (such as alumina, zirconia, 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, high response sensitivity, etc.

[0003] However, in the actual application of existing alcohol-based fuel tail gas monitoring sensors, carbon monoxide and nitrogen dioxide often coexist in the alcohol-based fuel tail gas. Since these two gases have opposite electron transfer directions with the sensor material, that is, carbon monoxide provides electrons to the material through an oxidation reaction, while nitrogen dioxide obtains electrons from the material through a reduction reaction, this competitive electron gain and loss process will cause signal interference with each other. Specifically, when carbon monoxide and nitrogen dioxide coexist, the electrical signal output by the sensor cannot accurately reflect the actual concentration of each component, reducing the accuracy and reliability of the detection. Moreover, during the continuous working process, the sensor needs to maintain a relatively high working temperature (usually in the range of 200 - 400 °C) to ensure 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. A slight fluctuation in the ambient temperature will cause this equilibrium to change, resulting in a change 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 the accuracy of detection. Summary of the Invention

[0005] To solve the deficiencies of the prior art, the embodiments of this application provide a method and device for detecting multi-component gases in the tail gas during the combustion process of alcohol-based fuels. This application solves the technical problems such as cross-sensitivity and baseline drift in the prior art.

[0006] An embodiment of the present application provides a method for detecting multi-component gases in the tail gas during the combustion process of alcohol-based fuels, including: successively soaking a ceramic tube in an alkali solution, roughening it with an acid solution, and ultrasonically cleaning it, preparing a two-component slurry, 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-controlled heating system to adjust the sensor temperature; obtaining the initial parameters of the gas sensor to establish a kinetic equation, introducing a compensation function and compensation parameters, and implementing signal sampling and processing to obtain the gas concentration value; using a platinum resistance temperature sensor to collect the temperature in real time, establishing a baseline drift algorithm and a calibration model, and regularly calibrating the zero point and range through calibration gas.

[0007] In a possible implementation manner, successively soaking a ceramic tube in an alkali solution, roughening it with an acid solution, and ultrasonically cleaning it, preparing a two-component slurry, coating it by dispensing, and sintering it in an oxygen atmosphere to obtain a double-coated gas sensor includes: soaking the ceramic tube in a sodium hydroxide solution with a preset concentration to remove surface oil stains, 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 coating adhesion; ultrasonically cleaning the ceramic tube in an ultrasonic cleaner with absolute 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 absolute ethanol and a dispersant, and then ball-milling; mixing nano-tin oxide, nano-tungsten oxide, platinum, and ruthenium according to a mass ratio, adding absolute ethanol and a dispersant, and then ball-milling; using a precision dispenser to coat the two slurries on both ends of the ceramic tube respectively, pre-drying after coating three times at intervals; placing the coated sample in a tube furnace, heating it up, introducing an oxygen atmosphere for sintering, and then cooling it down to obtain a double-coated gas sensor.

[0008] In a possible implementation manner, 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-controlled heating system to adjust the sensor temperature includes: connecting the gas sensor to the single-chip microcomputer, and using an internal analog-to-digital converter to collect the sensor resistance signal; constructing a signal conditioning circuit using a Wheatstone bridge structure, and constructing a signal amplification circuit through an operational amplifier; connecting the display module to the single-chip microcomputer through a communication interface, and configuring a reset circuit; constructing a sensor heating circuit using pulse width modulation, and implementing temperature control through a closed-loop control algorithm; using a platinum resistance in cooperation with a temperature conversion module for temperature collection, 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 and processing are performed to obtain the gas concentration value, including: obtaining the initial resistance value, sensitivity coefficient, response rate constant and cross-sensitivity coefficient of the sensor; establishing the kinetic equation of the adsorption-desorption process of gas molecules on the sensor surface; introducing a non-linear compensation function, and obtaining the compensation parameters by the least square method; performing signal acquisition and processing to obtain the gas concentration value based on the kinetic equation and the compensation parameters.

[0010] In one possible implementation, the platinum resistance temperature sensor is used to collect the temperature in real time, a baseline drift algorithm and a calibration model are established, and zero point and range calibration are performed regularly with standard gas, including: using a four-wire platinum resistance temperature sensor to cooperate with a temperature conversion module to collect temperature data; establishing a baseline drift detection algorithm to obtain the temperature coefficient and the standard working 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; performing range calibration with standard gas and updating the sensitivity coefficient.

[0011] In one possible implementation, the introduction of a non-linear compensation function and the obtaining of compensation parameters by the least square method include: , where represents the compensation parameter, represents the compensation weight coefficient, represents the non-linear modulation factor, represents the gas concentration, represents the compensation weight coefficient, represents the non-linear modulation factor, represents the gas concentration, represents the hyperbolic sine function.

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

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

[0014] The embodiments of the present application also provide a multi-component gas detection device for the tail gas during the combustion of alcohol-based fuel, including: a processor, a memory, and a system bus; wherein, the processor and the memory are connected through the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, and when the instructions are executed by the processor, the processor executes the method described in any one of the above embodiments.

[0015] In a multi-component gas detection method and device for the tail gas during the combustion of alcohol-based fuel provided as above, the embodiments of the present application can suppress the cross-sensitivity effect through a non-linear compensation method, thereby more accurately detecting the concentrations of carbon monoxide and nitrogen dioxide in the tail 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 calibration model are established. By real-time monitoring the temperature change to dynamically adjust the calibration parameters and periodically performing baseline calibration during the detection process, the baseline drift can be suppressed, the repeatability and stability of the measurement are improved, and thus the measurement accuracy is improved. By using the precision dispensing coating and high-temperature sintering processes to prepare the double-layer gas-sensitive sensor, the bonding force 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 technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic flow chart of a multi-component gas detection method for the tail gas during the combustion of alcohol-based fuel provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Now, various exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps described in these embodiments do not limit the scope of the present disclosure.

[0019] Those skilled in the art can understand that terms such as "first" and "second" 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 indicate an inevitable logical order between them. It should also be understood that in the embodiments of the present disclosure, "a plurality of" may refer to two or more, and "at least one" may 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 a clear limitation or contrary indication in the context, it can generally be understood as one or more. In addition, the term "and / or" in the present disclosure is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present disclosure generally represents an "or" relationship between the associated objects before and after. It should also be understood that the present disclosure emphasizes the differences between various embodiments, and their similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail one by one.

[0020] Meanwhile, it should be understood that for the convenience 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 merely illustrative and in no way constitutes a limitation on the present disclosure and its application or use. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. It should be noted that: similar reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0022] Figure 1 It is a schematic flow diagram of a multi-component gas detection method for real-time monitoring of tail gas during the combustion process of alcohol-based fuel provided for the embodiments of the present application.

[0023] It should be noted that currently, the monitoring of alcohol-based fuel tail gas mainly adopts the method of a bimetallic oxide composite sensor, and different sensitive materials are loaded on a ceramic substrate to achieve the detection of 、 and other gases. The common practice is to , Metal oxides such as are used as the base materials, and the sensitivity and selectivity are improved by doping noble metals or other metal oxides.

[0024] Due to the competitive mechanism of electron gain and loss reactions in the exhaust gas of alcohol-based fuels and When both gases are present, a cross-sensitivity problem will occur. The specific manifestations are as follows: undergoes an oxidation reaction with the sensor surface to release electrons, while undergoes a reduction reaction with the sensor surface to obtain electrons. This mutual interference of electron transfer leads to distorted sensing signals. At the same time, existing sensors have a baseline drift problem under high-temperature working conditions, mainly manifested as the zero-point resistance of the sensor changing over time. This drift stems from the dynamic change of the oxygen species adsorbed on the material surface caused by temperature fluctuations, making the output signal of the sensor unstable and affecting the measurement accuracy.

[0025] To address the cross-sensitivity and baseline drift problems, the embodiments of this application disclose a multi-component gas detection method for real-time monitoring of exhaust gas during the combustion process of alcohol-based fuels. This method is mainly used for real-time monitoring of and gases during the combustion process of alcohol-based fuels. By respectively loading a carbon monoxide sensor coating and a nitrogen dioxide sensor coating at both ends of the ceramic tube, and cooperating with a dual-channel signal processing method with nonlinear compensation and a baseline correction method with adaptive temperature compensation, accurate detection of (1.0 - 300 ppm) and (2.0 - 100 ppm) in the exhaust gas is achieved.

[0026] The specific implementation is as Figure 1 shown. At step S101, the ceramic tube is successively soaked in an alkali solution, coarsened with an acid solution, and ultrasonically cleaned. After preparing a two-component slurry, it is coated by dispensing, and sintered in an oxygen atmosphere to obtain a double-coated gas sensor. It includes: soaking the ceramic tube in a sodium hydroxide solution with a preset concentration to remove surface oil stains, and then rinsing it with deionized water until neutral; soaking the ceramic tube in a hydrochloric acid solution with a preset concentration to roughen the surface and increase the coating adhesion; ultrasonically cleaning the ceramic tube with absolute ethanol in an ultrasonic cleaner, 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 absolute ethanol and a dispersant, and then ball-milling; mixing nano-tin oxide, nano-tungsten oxide, platinum, and ruthenium according to a mass ratio, adding absolute 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, coating three times at intervals and then pre-drying; heating the coated sample in a tube furnace, introducing an oxygen atmosphere for sintering, and then cooling to obtain a double-coated gas sensor.

[0027] In one embodiment, a ceramic tube substrate is first prepared. An alumina ceramic tube with high purity (99.9%) is used, 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 by mass for 15 min to remove surface oil stains, and then rinse it with deionized water until neutral; then soak it in a 5% hydrochloric acid solution by mass for 10 min for surface roughening to increase the coating adhesion; finally, ultrasonically clean it in an anhydrous ethanol solution in a 40 kHz ultrasonic cleaner for 15 min and dry it in an 80 °C drying oven for 2 h.

[0028] The preparation of the carbon monoxide sensor coating adopts the following ratio: weigh , nano , and in a mass ratio of 1:10:2:2. Among them, the particle size of nano should be controlled within the range of 30 - 50 nm, and the specific surface area is greater than 35 m² / g. Mix the above raw materials with an appropriate amount of anhydrous ethanol (the alcohol-to-material ratio is 3:1) and a dispersant (accounting for 0.8% of the total mass of the powder), ball-mill in a planetary ball mill at 300 rpm for 4 h, with a ball-to-material ratio of 4:1, and use zirconia grinding balls. The ball-milled slurry is filtered through a 100-mesh sieve, left standing for 2 h to exhaust air, and then reserved for use.

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

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

[0031] The above-mentioned 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 - sensing characteristics of the sensor are enhanced, enabling the sensor to maintain good detection performance even in a relatively low concentration range.

[0032] At step S102, the gas - sensitive 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 - controlled heating system is constructed to adjust the sensor temperature. This includes: connecting the gas - sensitive sensor to the single - chip microcomputer, using an internal analog - to - digital converter to collect the sensor resistance signal; constructing a signal - conditioning circuit using a Wheatstone bridge structure and a signal - amplification circuit using an operational amplifier; connecting the display module to the single - chip microcomputer through a communication interface and configuring a reset circuit; constructing a sensor heating circuit using pulse - width modulation and achieving temperature control through a closed - loop control algorithm; using a platinum resistance in combination with a temperature - conversion module for temperature acquisition and using a platinum wire as the heating wire for winding.

[0033] The above - mentioned step S102 constructs a temperature - controlled heating system, uses a closed - loop control algorithm to achieve precise temperature control, ensures that the sensor operates at the optimal working temperature, and reduces the influence of temperature fluctuations on the measurement results.

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

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

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

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

[0038] Among them, introducing a non-linear compensation function and obtaining the compensation parameters by the least squares method includes: , where represents the compensation parameter, represents the compensation weight coefficient, represents the non-linear modulation factor, represents the gas concentration, represents the compensation weight coefficient, represents the non-linear modulation factor, represents the gas concentration, represents the hyperbolic sine function.

[0039] Among them, performing signal acquisition and processing to obtain the gas concentration value based on the kinetic equation and the compensation parameters includes: , where represents the output signal, represents the resistance change value, represents the compensation parameter.

[0040] Specifically, in an implementation scenario, when the tail gas is introduced into the detection cavity, the CO and NO2 molecules undergo an electron transfer reaction with the sensor surface. At a working temperature of 225°C, the adsorption-desorption process of gas molecules on the sensor surface follows the pseudo-first-order reaction kinetics. The resistance change of the sensor satisfies the following kinetic equation: , where the initial parameters are obtained by calibration with standard gas:

[0041] : The initial resistance of the sensor is 23.6 kΩ, The initial resistance of the sensor is 31.8 kΩ (measured under the conditions of 25°C and 50% RH); = 0.0427, = 0.0683 (sensitivity coefficient calibrated with 50 ppm standard gas); = 0.0234 s -1 , = 0.0198 s -1 (response rate constant, measured using the step response method); = 0.00876 (cross-sensitivity coefficient, calibrated in a mixed gas atmosphere of 25 ppm + 10 ppm ); is the response time (s); and is the gas concentration (ppm).

[0042] To eliminate the influence of cross-sensitivity, a nonlinear compensation function is introduced: , and the compensation parameters are obtained by optimizing using the least squares method: = 0.0156, = 0.0234 (compensation weight coefficient), = 0.00432, = 0.00567 (nonlinear modulation factor).

[0043] The final sensor output signal is expressed as: . The system completes a full signal acquisition and processing process every 0.5 s: First, 16 AD samplings are taken and averaged to reduce random noise; then the sampled values are converted into resistance values through the calibration curve; then the initial gas concentration value is calculated by substituting into the kinetic equation; finally, the final concentration value is obtained through correction by the nonlinear compensation function.

[0044] At step S104, a platinum resistance temperature sensor is used to collect the temperature in real time, a baseline drift algorithm and a calibration model are established, and zero and range calibrations are performed regularly with calibration gases.

[0045] Further, it includes: using a four-wire platinum resistance temperature sensor in cooperation 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 calibration by cutting off the sampling gas path and introducing clean air; performing range calibration with standard gases and updating the sensitivity coefficient.

[0046] Among them, establishing a periodic baseline correction model includes: , where represents the corrected resistance value, represents the original resistance value, represents the baseline drift value, represents the dynamic attenuation coefficient, represents the current time, represents the last calibration time point.

[0047] Specifically, in one implementation scenario, to solve the problem of baseline drift, the system collects temperature data every 100 ms for real-time compensation. A PT100 platinum resistance temperature sensor can be used, and the four-wire connection method is adopted to eliminate the influence of lead resistance. In cooperation with the MAX31865 temperature conversion module, the temperature measurement accuracy is ±0.1 °C. The baseline drift detection algorithm is as follows: , where the parameter settings are: : The sensor is 23.6 kΩ, The sensor is 31.8 kΩ (calibration value at 25 °C); = -0.00432 K -1 (temperature coefficient, calibrated in the range of 180 - 260 °C); = 225 °C (standard operating temperature); is the real-time temperature, and the sampling frequency is 10 Hz.

[0048] Next, a periodic baseline correction model is constructed: , where the dynamic attenuation coefficient: , = 0.0167 s -1 (initial attenuation coefficient, determined according to the aging characteristics of the sensor); = 2.34 (temperature change rate influence factor, calibrated through temperature cycle experiments); is the previous correction time point; is the temperature change rate, calculated using 5-point smoothed differentiation.

[0049] The system performs an automatic zero calibration at regular intervals. For example, every 30 minutes, the sampling gas path is cut off, and after introducing clean air for 3 minutes, the baseline value is collected; if the baseline deviation exceeds ±2%, then the value is updated. Every 2 hours, a standard gas (50 ppm + 20 ppm ) is used for range calibration, and the sensitivity coefficient is updated according to the deviation between the measured value and the standard value.

[0050] Next, taking the exhaust gas monitoring of a methanol fuel generator set as an example, the embodiments of the present application are further described.

[0051] 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 8 mm and is 1.2 m away from the exhaust port. The outside of the pipeline is wrapped with a 50 mm 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 0.8 L / min. The sampling pipeline is kept at a 45° inclination to avoid condensate backflow. The gas path system is equipped with a particle filter (accuracy 0.3 μm) and a condensate separator.

[0052] The front end of the sampling system is equipped with a heating pipe section set at 180 °C, with a length of 0.3 m to prevent water vapor condensation. Standard gas (50 ppm + 20 ppm , with a relative uncertainty ≤ 2%) is used for calibration every 2 h. The calibration gas is switched to enter through a three-way valve, and the flow rate is kept consistent with the sampling gas flow rate. The system has an automatic backflush function and performs backflush cleaning regularly at 2 am every day.

[0053] In actual tests, the system collects data every 0.5 s. The sampled data is filtered by five-point median filtering to eliminate accidental interference. When it is detected that the concentration suddenly rises (>150 ppm) and lasts for more than 3 s, the system automatically triggers an audible and visual alarm. The measurement data is transmitted to the upper computer through an RS485 interface (baud rate 9600, using the Modbus-RTU protocol), and the concentration change trend and temperature status are displayed in real time.

[0054] According to the on-site test results for 30 consecutive days, this method has the following performance characteristics at a working temperature of 225 °C: Detection accuracy: ±3% (in the range of 1.0 - 300 ppm), Detection accuracy: ±4% (in the range of 2.0 - 100 ppm), response time (T90) is less than 12 s, repeatability error ≤ 2.5%, zero drift ≤ ±2% FS / week, span drift: ≤ ±3% FS / month, environmental temperature influence: ≤ ±0.2% FS / °C (in the range of 5 - 40 °C), environmental humidity influence: ≤ ±0.3% FS / 10% RH (in the range of 20% - 85% RH)

[0055] In addition, it should be noted that during the sensor preparation process, the ball milling time of the slurry should not exceed the specified value to avoid excessive agglomeration of the powder, which may affect the gas-sensing performance. The ball-milled slurry should be sieved in time and its viscosity should be checked. The sintering heating rate should be strictly controlled within 5°C / min to avoid coating cracking caused by thermal stress. Sufficient oxygen flow must be introduced during sintering to ensure full oxidation of the metal oxide. The working temperature fluctuation must be controlled within the range of ±2°C. Excessive temperature will accelerate sensor aging, while 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 should be cleaned once a week to check its tightness and remove accumulated dust. The filter element should be replaced every 1 to 3 months according to the usage environment. The condensate separator should be drained daily. When the environmental humidity exceeds 85%RH, a silica gel drying tube should be installed for pretreatment. The silica gel should be replaced in time when its color change exceeds 2 / 3. When the system is not in use for a long time, the sensor should be placed in a dry environment. The standard gas cylinder should not be used for more than 1 month to avoid affecting the calibration accuracy due to concentration changes. When replacing the cylinder, an overlapping usage period of more than 30 minutes should be reserved for cross-checking. When the system is used for the first time or restarted after a long-term shutdown, at least 4 hours of preheating is required. During this period, standard gas calibration should be performed every 30 minutes until the indication is stable. Regularly check the data communication quality. The RS485 bus cable can be a shielded twisted pair with a total length not exceeding 500m, and 120Ω terminal resistors should be added at both ends.

[0056] In summary, on the one hand, the embodiment of the present application is based on the electron transfer kinetics principle between gas molecules and the sensor surface. By introducing the hyperbolic sine function as a non-linear 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 contributions of different gases.

[0057] On the other hand, it is based on the temperature-resistance characteristics of the sensor. By establishing a baseline drift detection algorithm and a periodic correction model, real-time compensation for the baseline drift caused by temperature fluctuations is achieved. The dynamically adjusted attenuation coefficient can adaptively adjust the correction intensity according to the temperature change rate to ensure the accuracy of the correction.

[0058] The non-linear compensation and the adaptive temperature compensation cooperate with each other, which not only solves the accuracy problem of gas cross-interference but also ensures the stability of the sensor signal, realizing reliable real-time monitoring.

[0059] Furthermore, an embodiment of the present application further provides a multi-component gas detection device for real-time monitoring of tail gas during the combustion process of alcohol-based fuel, including: a processor, a memory, and a system bus; the processor and the memory are connected through the system bus; the memory is used to store one or more programs, and the one or more programs include instructions that, when executed by the processor, cause the processor to execute any of the above methods.

[0060] Furthermore, an embodiment of the present application further provides a computer program product that, when running on a terminal device, causes the terminal device to execute any of the above processing methods.

[0061] From the description of the above embodiments, those skilled in the art can clearly understand that all or part of the steps in the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing 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 each embodiment or some parts of the embodiments of the present application.

[0062] It should be noted that the embodiments in this specification are described in a progressive manner, and the key point of each embodiment is to describe the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0063] It should also be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0064] 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 can 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 rather 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 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; Perform signal acquisition and processing to obtain gas concentration values ​​based on kinetic equations and compensation parameters; 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; 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, represents compensation parameters; Use platinum resistance temperature sensor to collect temperature in real time, establish baseline drift algorithm and correction model, and perform zero point and range calibration regularly with standard gas; The baseline drift algorithm is: ,in, :for sensor, whose value is 23.6kΩ, for sensor, its value is 31.8kΩ; λ is the temperature coefficient and = -0.00432 K -1 ; is the standard operating temperature, and = 225℃; It is the real-time temperature with a sampling frequency of 10Hz.

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, 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.

5. The multi-component gas detection method according to claim 4, 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.

6. 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 5.

Images