A cremation workshop online air quality monitoring system and operation processing method thereof

Abstract

An online air quality monitoring system for a cremation workshop includes a timer, a single-chip microcomputer connected to the timer, and a power switch circuit connected to the single-chip microcomputer control, wherein the power switch circuit is connected between an external power supply and a first internal power supply, and the automatic control circuit also includes a power management chip connected between the first internal power supply and a second internal power supply. The present invention also discloses an operation processing method for an online air quality monitoring system for a cremation workshop. The present invention can control the working time of the sensor according to the cremation workshop scene, effectively prolong the service life of the gas sensor; and can reduce or offset the adverse effects of repeated power on and off on the sensor; and by correcting the sensor current, the accuracy of the sensor output result can be improved.

Description

Technical Field

[0001] The invention belongs to the field of electronics and relates to air quality monitoring technology, and in particular to an online air quality monitoring system for a cremation workshop and an operation processing method thereof. Background Art

[0002] The cremation workshop is an environment with many types of pollutants in the air and a relatively poor environment. When the gas sensor works in this environment, the life of the gas sensor will be lower than the design value, so the gas sensor needs to be replaced frequently. In the application scenario of air quality monitoring in the cremation workshop, gas sensors are consumable devices. At the same time, the cost of gas sensors with high measurement accuracy and single-item sensitivity has always been relatively high. Therefore, if it is possible to extend the service life of the gas sensor without reducing the actual working efficiency of the system, it will be of great significance to optimize the actual use cost of the system.

[0003] Most of the gas sensors used in the cremation workshop air quality monitoring system are electrochemical sensors. When the sensor is working, it needs to be heated first, and then the relevant chemical sensitive materials in the sensor will react with the relevant components in the air and generate electrical signals, which are amplified and output to the outside. The factors affecting the life of the sensor are mainly that the chemical sensitive materials in the sensor will slowly degrade over time and eventually fail; in addition, the interference of temperature drift on the electrochemical gas sensor, especially SO 2 Interference from electrochemical sensors causes the collected data to be inaccurate, which can easily lead to deviations in the adjustment of the air-conditioning system. Summary of the invention

[0004] In order to overcome the technical defects of the prior art, the present invention discloses an online air quality monitoring system for a cremation workshop and an operation processing method thereof.

[0005] The online air quality monitoring system for a cremation workshop of the present invention comprises a timer, a single-chip microcomputer connected to the timer, and a power switch circuit connected to the control of the single-chip microcomputer, wherein the power switch circuit is connected between an external power supply and a first internal power supply, and the automatic control circuit further comprises a power management chip connected between the first internal power supply and a second internal power supply, wherein the first internal power supply supplies power to a gas sensor, and a sensor energy storage capacitor is connected between the first internal power supply and the ground, and the automatic control circuit further comprises a comparator, wherein one input end of the comparator samples from the first internal power supply, and the other input end is connected to a reference voltage, and the output end of the comparator is connected to the single-chip microcomputer.

[0006] Preferably, the two output terminals of the comparator are respectively connected to common terminals of two pairs of series resistors, and each pair of series resistors is respectively connected between the first internal power supply and ground, and between the second internal power supply and ground.

[0007] Preferably, the power switch circuit includes a transistor and a PMOS tube, the base of the transistor is connected to the single-chip microcomputer, the emitter is grounded, the collector is connected to the gate of the PMOS tube, the source and drain of the MOS tube are respectively connected to an external power supply and a first internal power supply, and the collector is also connected to the external power supply through a current limiting resistor.

[0008] Preferably, it also includes a cable and multiple coding switches, the cable includes multiple sockets, the control end of the coding switch is connected to the microcontroller control, the input end of the coding switch is connected to the external power supply, the output end of the coding switch is connected to the power end of the sensor through the socket on the cable, the signal output end of the sensor is connected to the input end of the selection circuit through the socket on the cable, and the output end and control end of the selection circuit are respectively connected to the microcontroller signal.

[0009] Furthermore, the control end of the coding switch includes an enabling end and a coding end, and the coding end is a code that can be manually controlled.

[0010] Furthermore, the gating circuit is one or more CD4052 chips connected in parallel.

[0011] The present invention also discloses an operation processing method of an online air quality monitoring system for a cremation workshop, which is characterized by comprising data processing of a sulfur dioxide sensor, specifically:

[0012] Get the best calibration temperature of the sensor;

[0013] The measured current is corrected according to the optimal calibration temperature.

[0014]

[0015] Where I is the current measured by the sensor, C(T) is the correction coefficient, I 0 (T) is the zero-point current corresponding to temperature T;

[0016] The correction factor

[0017] I 0 (T), I A (T) represent the sensor zero point current and output current at the corresponding temperature respectively.

[0018] Preferably, the optimal calibration temperature is determined as follows:

[0019] Select different temperature points respectively, test the measured current when zero-level air without sulfur dioxide is passed through, and fit the temperature characteristic curve of zero-point current;

[0020] The sulfur dioxide gas with different concentrations was introduced respectively, and different temperature points were selected again to measure the reaction current, and the reaction current temperature characteristic curves under different concentrations were fitted;

[0021] The difference between the reaction current temperature curve of different concentrations and the zero-point current curve is taken to obtain the net reaction current temperature characteristic curve; the current at each typical measurement temperature point on the net reaction current temperature characteristic curve is converted into the corresponding sulfur dioxide concentration measurement value;

[0022] For each temperature, calculate the error between the measured value and the actual value at different concentrations, and find the sum of their absolute values. The temperature with the smallest sum of absolute values ​​is taken as the optimal calibration temperature.

[0023] Preferably, it runs according to a specified time period and running time length.

[0024] Preferably, the method further includes time correction for the measured current, and the specific method is as follows:

[0025] A series of known correction factors related to the use time are obtained through experiments;

[0026] The correction factor for the current time t can be calculated as follows:

[0027] Where t0 and t1 are the starting point and end point of the time span, respectively. Pt represents the correction factor of the current time. The subscripts represent different times. t0 , P t1 Indicates different known correction factors;

[0028] Then the SO2 sensor concentration output at the current time t is:

[0029] .

[0030] The present invention can control the working time of the sensor for the cremation workshop scene, effectively prolonging the service life of the gas sensor; and can reduce or offset the adverse effects of repeated power on and off on the sensor; and by correcting the sensor current, the accuracy of the sensor output result can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a specific implementation of the online air quality monitoring system for a cremation workshop according to the present invention;

[0032] Figure 2 A schematic diagram of a specific implementation of the power switch circuit of the present invention;

[0033] Figure 3 A schematic diagram of a specific application mode of the quality monitoring system of the present invention;

[0034] Figure 4 It is a schematic diagram of a specific embodiment of the zero-point current-temperature characteristic curve and the reaction current-temperature characteristic curve of the present invention;

[0035] The reference numerals in the figure are VIN-external power supply, V51-first internal power supply, V33-second internal power supply, VC-power supply control signal, VREF-reference voltage, COMP-comparator, C1-sensor energy storage capacitor, LDO-linear regulator, T-transistor, M-PMOS tube, S1-gas sensor, TC-timer, R1-first voltage dividing resistor, R2-second voltage dividing resistor, R5-base resistor, R6-reset resistor, R7-current limiting resistor. DETAILED DESCRIPTION

[0036] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0037] like Figure 1 As shown, the online air quality monitoring system for a cremation workshop of the present invention includes a timer TC, a single-chip microcomputer connected to the timer, and a power switch circuit connected to the single-chip microcomputer control, the power switch circuit is connected between an external power supply V50 and a first internal power supply V51, the automatic control circuit also includes a power management chip connected between the first internal power supply and the second internal power supply V33, the first internal power supply supplies power to the gas sensor S1, a sensor energy storage capacitor C1 is connected between the first internal power supply V51 and the ground, a voltage stabilizing capacitor C2 is connected between the second internal power supply and the ground, the automatic control circuit also includes a comparator COMP, one input end of the comparator samples from the first internal power supply, the other input end is connected to a reference voltage, and the output end of the comparator is connected to the single-chip microcomputer.

[0038] The present invention can solve the problem of drastically shortened life of the gas sensor due to long-term operation. Through the periodic operation of the sensor, the gas detection requirements in the cremation workshop can be met and the service life of the sensor can be extended.

[0039] By presetting, the timer periodically sends a power on / off signal to the single-chip microcomputer. After receiving the power on signal, the single-chip microcomputer sends a power control signal VC to turn on the power switch circuit, so that the external power supply is connected to the first internal power supply. The first internal power supply is powered and starts to power the gas sensor. At the same time, the second internal power supply is also powered by the power management chip. The external power supply and the first internal power supply are generally high in voltage, for example, 5V. The second internal power supply can power devices such as single-chip microcomputers and comparators, generally 2.7-3.3V. The second internal power supply is usually connected to a voltage stabilizing capacitor C2. The static power consumption of devices such as single-chip microcomputers and comparators is low. During the time when the power switch circuit is closed, the voltage drop on the voltage stabilizing capacitor is limited, which can still meet the requirements of devices such as single-chip microcomputers and comparators to maintain operation. Devices such as single-chip microcomputers and comparators can be powered by an external power supply or by a second internal power supply.

[0040] As the voltage of the sensor energy storage capacitor connected to the first internal power source continues to rise, the comparator detects the change in the voltage value of the first internal power source through the sampling circuit. After the comparison with the reference voltage is detected and the set threshold voltage is reached, a signal is sent to the single-chip microcomputer, and the single-chip microcomputer starts to read the gas detection value of the gas sensor at this time and store or send it. The measurement operation is started only when the voltage of the first internal power source reaches the preset value to prevent the measurement result deviation of the sensor caused by insufficient voltage.

[0041] After the microcontroller detects the detection data of the gas sensor, the timer sends a shutdown signal, the first internal power supply is disconnected from the external power supply, and the sensor is no longer heated to maintain the working state after power is cut off. The capacitance value of the sensor energy storage capacitor is relatively large, generally around the farad level. The gas sensor itself is a resistive device with a large static working current. After using a farad-level large capacitor, the power-off time can be extended to several minutes, and the power supply to the sensor is slowly reduced, so that the sensor will not cool down quickly, which greatly reduces the impact of sensor temperature changes caused by repeated power cuts, which causes the sensor accuracy to deteriorate or the life to shorten. After the sensor loses power, the internal temperature of the gas sensor decreases, and the chemical sensitive material no longer maintains an active state, extending the service life.

[0042] For the sampling method of the comparator, such as Figure 1 As shown, the two output terminals of the comparator COMP are respectively connected to the common terminals of two pairs of series resistors, and each pair of series resistors is respectively connected between the first internal power supply and the ground, and between the second internal power supply and the ground. Figure 1 In the specific implementation shown, a first voltage-dividing resistor R1 and a second voltage-dividing resistor R2 are connected in series between the first internal power supply and the ground, and the reference voltage VREF can be formed by dividing the voltage of the voltage-dividing resistors connected in series between the second internal power supply and the ground.

[0043] Figure 1In the specific implementation shown, a specific implementation of the power switch circuit is given, the power switch circuit includes a transistor T and a PMOS tube M, the base of the transistor is connected to the single chip computer, the emitter is grounded, the collector is connected to the gate of the PMOS tube, the source and drain of the MOS tube are respectively connected to the external power supply and the first internal power supply, and the collector is also connected to the external power supply through a current limiting resistor R7. The gate capacitor of the PMOS tube M is charged by the rapid opening of the transistor T, so that it quickly reaches the opening voltage, thereby improving the opening speed. The collector is connected to the external power supply through a current limiting resistor, which can limit the collector current, and after the transistor is turned off, the gate of the PMOS tube is pulled up by the external power supply to achieve synchronous automatic closing. A reset resistor R6 can be connected between the base and emitter of the transistor, and when the single chip computer does not output a signal, the base voltage of the transistor is automatically lowered to turn off the transistor.

[0044] The single chip microcomputer is STM32F1030C8T6, and the gas sensor can be ZE03-CO, ZE03-SO2, ZE03-NO, ZE03-O3, etc.

[0045] Figure 1 In the specific implementation shown, in order to facilitate the rapid replacement of the sensor, it may also include a flat cable and multiple coding switches, the flat cable includes multiple sockets, the control end of the coding switch is connected to the microcontroller control, the input end of the coding switch is connected to the external power supply, the output end of the coding switch is connected to the power end of the sensor through the socket on the flat cable, the signal output end of the sensor is connected to the input end of the selection circuit through the socket on the flat cable, and the output end and control end of the selection circuit are respectively connected to the microcontroller signal.

[0046] The power supply of each sensor is controlled by a coding switch, which is controlled by a single-chip microcomputer. The control end of the coding switch may include an enable end and a coding end. The enable end is used to control the opening and closing of the coding switch, and the number of the coding switch is read through the coding end. The coding end is a code that can be manually controlled. Different sensors are identified by setting codes, so that the single-chip microcomputer can identify the sensor connected to the code by reading the code of the coding end. The coding switch can select a four-bit coding switch, of which 1 bit is the enable end and 3 bits are the coding end.

[0047] By reading the coding status of the gas sensor, the type of installed gas sensor can be manually configured without rewriting the built-in program of the acquisition system; when the gas sensor is in working state, the relevant measurement results can be directly uploaded through the selection circuit. The microcontroller can poll the data communication port of each sensor in turn by controlling the signal selection circuit and output the result data periodically.

[0048] The gating circuit is one or more CD4052 chips connected in parallel. A single CD4052 chip can achieve gating for four inputs. Figure 1 The specific implementation shown has 5 sensors and 5 inputs, and the five-choice gating function can be realized by connecting two CD4052 chips in parallel. The single-chip microcomputer can be selected as STM32F407ZGT6, and the pin for outputting the gating signal of the single-chip microcomputer can be any pin in PC0-PC12 in the manual, the pin for reading the coding switch code is any remaining pin in PC0-PC12, and the pin for receiving the signal after gating is any pin in PB8-PB15.

[0049] By adopting the cremation workshop online air quality monitoring system of the present invention, the working time of the sensor can be controlled according to the cremation workshop scene, effectively extending the service life of the gas sensor; and the adverse effects of repeated power on and off on the sensor can be reduced or offset.

[0050] like Figure 3 As shown, the present invention can adjust the air quality of the fresh air system, desulfurization and deacidification spray system, electrostatic dust removal system and other equipment in the workshop by controlling the relay control module through the output signal of the single-chip microcomputer according to the ambient air data fed back by the sensor, and upload the data to the cloud server through the network communication module and further distribute it to personal computers, mobile phones, tablet computers, large-screen TVs and other terminals for display and broadcast.

[0051] The present invention can be implemented based on Internet of Things technology and cloud server architecture. Compared with the traditional cremation workshop air quality collection system, the cremation workshop online air quality monitoring system of the present invention has the following advantages.

[0052] Improve data measurement accuracy through an algorithm that combines temperature and sensor cumulative operating time;

[0053] Gas sensors can be flexibly configured to adapt to cremation workshops of different construction levels;

[0054] The working logic of the gas sensor can be configured to extend the life of the gas sensor;

[0055] It can be connected to the air purification system of the cremation workshop, or directly drive external purification equipment such as spray valves, desulfurization towers, etc.

[0056] For cremation workshops, the detection of sulfur dioxide SO2 is a basic detection item. At present, the electrochemical SO 2 In the detection technology, when applying the curve fitting method, the reference compensation temperature is generally ignored, and the laboratory temperature of 20℃ is usually directly used as the calibration temperature.

[0057] In order to reduce temperature errors, the optimal output temperature of the sensor, that is, the temperature with the smallest comprehensive error, should be used as the calibration temperature; in addition, when compensating for temperature based on the overall output current of the sensor, the temperature drift of the zero-point current should be considered.

[0058] To this end, the present invention also discloses an operation processing method based on the above-mentioned cremation workshop online air quality monitoring system, wherein the data processing of the sulfur dioxide sensor is specifically as follows:

[0059] Select different temperature points respectively, test the measured current when zero-level air without sulfur dioxide is passed through, and fit the temperature characteristic curve of zero-point current;

[0060] The sulfur dioxide gas with different concentrations was introduced respectively, and different temperature points were selected again to measure the reaction current, and the reaction current temperature characteristic curves under different concentrations were fitted;

[0061] Get the best calibration temperature of the sensor;

[0062] The measured current is corrected according to the optimal calibration temperature.

[0063]

[0064] Where I is the current measured by the sensor, C(T) is the correction coefficient, I 0 (T) is the zero-point current corresponding to temperature T;

[0065] The correction factor

[0066] Among them I 0 (T), I 0 (Tc) represents the zero-point current value at the current temperature and the optimal calibration temperature, respectively.

[0067] I A (T), I A (Tc) represents the output current at the current temperature and the optimal calibration temperature, respectively, and is determined according to the concentration corresponding to the current I before correction.

[0068] For example, you can select multiple temperature points of 5, 10, 20, 30, and 40°C, test the measured current when zero-level air without sulfur dioxide is passed through, and fit the temperature characteristic curve of the zero-point current; Figure 4 The lowermost curve in the coordinate system of .

[0069] Then, 3PPM, 10PPM, and 16PPM sulfur dioxide gas were introduced respectively, and multiple temperature points of 5, 10, 20, 30, and 40°C were selected again to measure the reaction current, and the reaction current temperature characteristic curves at various concentrations were fitted; Figure 4shown.

[0070] Assume that the optimal calibration temperature T is selected C The temperature is 26 degrees Celsius, the temperature when the sensor is detecting is 40 degrees Celsius, and the detection current is I=23 mA;

[0071] Assumptions Figure 4 The obtained curves have zero-point currents of 3 mA and 2.4 mA at 40°C and 26°C, respectively, that is, I 0 (T) = 3 mA, I 0 (Tc) = 2.4 mA;

[0072] The current I detected by the sensor is 22.5 mA, and the corresponding sulfur dioxide concentration is 10 PPm. Figure 4 The 10PPm curve obtained in the experiment shows that the current values ​​corresponding to the detection temperature and the optimal calibration temperature on the curve are 23.5 mA and 22.3 mA respectively, that is, I A (T) = 23.5 mA, I A (Tc) = 22.3 mA, then we can calculate

[0073] C(T) = I A (40)-I O (40) / I A (26)-I O (26) = (23.5-3) / (22.3-2.4) = 1.03;

[0074] Corrected current Ic=I-I 0 (T) / C(T) = 23-3 / 1.03 = 19.4 mA, and the corresponding sulfur dioxide concentration is corrected to 9.85 PPm.

[0075] In the prior art, the optimal calibration temperature is directly selected as a fixed 20 degrees Celsius, but the optimal calibration temperature of each sensor is not consistent. The following steps can be used to select the optimal calibration temperature:

[0076] The net reaction current-temperature characteristic curve is obtained by subtracting the reaction current-temperature curve of different concentrations obtained previously from the zero-point current curve;

[0077] Convert the current at each typical measurement temperature point on the net reaction current temperature characteristic curve into a corresponding sulfur dioxide concentration measurement value;

[0078] For each temperature, calculate the error between the measured value and the actual value at different concentrations, and find the sum of their absolute values. The temperature with the smallest sum of absolute values ​​is taken as the optimal calibration temperature.

[0079] As mentioned above, multiple temperature points of 5, 10, 20, 30, and 40°C were selected to test the measured current when zero-grade air without sulfur dioxide was introduced, and the temperature characteristic curve of the zero-point current was fitted; Figure 4 The lowermost curve in the coordinate system of .

[0080] Then, 3PPM, 10PPM, and 16PPM sulfur dioxide gas were introduced respectively, and multiple temperature points of 5, 10, 20, 30, and 40°C were selected again to measure the reaction current, and the reaction current temperature characteristic curves at various concentrations were fitted; Figure 4 shown.

[0081] Subtract the reaction current temperature characteristic curve from the zero point current temperature characteristic curve to obtain the net reaction current temperature characteristic curve; for example, at 5 degrees Celsius, when gases with sulfur dioxide contents of 3, 10, and 16 ppm are introduced, the obtained sensor currents are calculated in the sensor matching algorithm to display gas concentrations of 3.2, 10.1, and 15.7 ppm, respectively. The absolute values ​​of the differences from the actual gas concentrations are 0.2, 0.1, and 0.3, respectively, and the sum of the absolute values ​​is 0.6; according to the above algorithm, the sum of the errors at each temperature is calculated, and the temperature with the smallest sum of the errors is selected as the optimal calibration temperature.

[0082] The SO2 sensor is an electrochemical sensor, which has the characteristic that the measurement results gradually drift and degrade as the accumulated working time increases. In addition, the deviation of the results of sensors of the same model will have an obvious linear relationship with time. Therefore, the measured values ​​of sensors that have been used and have known accumulated working time under standard conditions can be compared with the standard values. Usually, the service life of SO2 gas sensors is about 2 years. Through experiments, a series of correction factors related to the use time are obtained, such as 30 days, 90 days, 180 days, 360 days, 540 days, and 720 days, and then the current correction factor is calculated using the linear interpolation method.

[0083] For example, for a sensor with a service life of 120 days, the known correction factor P is obtained by measuring at t0 = 90 days and t1 = 180 days. t0 , P t1 ;

[0084] The correction factor for the current time t=120 days can be calculated as follows:

[0085] Then the SO2 sensor concentration output at the current time t is:

[0086] .

[0087] Through the above processing method, the linear offset of the sensor over time can be effectively corrected.

[0088] The above embodiments respectively correct the optimal calibration temperature, zero drift and time drift of the sensor, thereby effectively improving the detection accuracy and data authenticity of the sensor.

[0089] The embodiments of the above method of the present invention may be provided as a method, a system, or a computer program product. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0090] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0092] The foregoing describes various preferred embodiments of the present invention. Unless the preferred implementation modes in various preferred embodiments are obviously self-contradictory or based on a certain preferred implementation mode, various preferred implementation modes can be arbitrarily superimposed and used in combination. The embodiments and specific parameters in the embodiments are only for clearly describing the invention verification process of the inventor, and are not used to limit the patent protection scope of the present invention. The patent protection scope of the present invention shall still be based on its claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should be included in the protection scope of the present invention.

Claims

1. An online air quality monitoring system for a cremation workshop, characterized in that: The air quality monitoring system comprises a timer, a single-chip microcomputer connected to the timer, and a power switch circuit connected to the single-chip microcomputer control, wherein the power switch circuit is connected between an external power supply and a first internal power supply, the air quality monitoring system further comprises a power management chip connected between the first internal power supply and a second internal power supply, the first internal power supply is used to power a gas sensor, a sensor energy storage capacitor is connected between the first internal power supply and the ground, the air quality monitoring system further comprises a comparator, one input end of the comparator is sampled from the first internal power supply, the other input end is connected to a reference voltage, and the output end of the comparator is connected to the single-chip microcomputer; The two output terminals of the comparator are respectively connected to the common terminals of two pairs of series resistors, and each pair of series resistors is respectively connected between the first internal power supply and the ground, and between the second internal power supply and the ground; The power switch circuit includes a transistor and a PMOS tube, the base of the transistor is connected to the single chip computer, the emitter is grounded, the collector is connected to the gate of the PMOS tube, the source and drain of the MOS tube are respectively connected to an external power supply and a first internal power supply, and the collector is also connected to the external power supply through a current limiting resistor.

2. The online air quality monitoring system according to claim 1, characterized in that: It also includes a cable and multiple coding switches, the cable includes multiple sockets, the control end of the coding switch is connected to the microcontroller control, the input end of the coding switch is connected to the external power supply, the output end of the coding switch is connected to the power end of the sensor through the socket on the cable, the signal output end of the sensor is connected to the input end of the selection circuit through the socket on the cable, and the output end and control end of the selection circuit are respectively connected to the microcontroller signal.

3. The online air quality monitoring system according to claim 2, characterized in that: The control end of the coding switch includes an enabling end and a coding end, and the coding end is a manually controlled code.

4. The online air quality monitoring system as claimed in claim 2, characterized in that: The gating circuit is one or more CD4052 chips connected in parallel.

5. A method for operating an online air quality monitoring system for a cremation workshop, characterized in that: The air quality monitoring system according to claim 1 is implemented, including data processing of the sulfur dioxide sensor, specifically: Get the best calibration temperature of the sensor; The measured current is corrected according to the optimal calibration temperature. ； Where I is the current measured by the sensor, C(T) is the correction coefficient, and I0(T) is the zero-point current at the corresponding temperature T; The correction factor ; I0(T),I A (T) represents the sensor zero current and output current at the corresponding temperature respectively; The optimal calibration temperature is determined as follows: Select different temperature points respectively, test the measured current when zero-level air without sulfur dioxide is passed through, and fit the temperature characteristic curve of zero-point current; The sulfur dioxide gas with different concentrations was introduced respectively, and different temperature points were selected again to measure the reaction current, and the reaction current temperature characteristic curves under different concentrations were fitted; The difference between the reaction current temperature curve of different concentrations and the zero-point current curve is taken to obtain the net reaction current temperature characteristic curve; the current at each typical measurement temperature point on the net reaction current temperature characteristic curve is converted into the corresponding sulfur dioxide concentration measurement value; For each temperature, calculate the error between the measured value and the actual value at different concentrations, and find the sum of their absolute values. The temperature with the smallest sum of absolute values ​​is taken as the optimal calibration temperature. The operation processing method is executed according to the specified time period and the operation time length; The operation processing method also includes time correction of the measured current, and the specific method is as follows: A series of known correction factors related to the use time are obtained through experiments; The correction factor for the current time t is calculated according to the following formula: ； Where t0 and t1 are the starting point and end point of the time span, respectively. Pt represents the correction factor of the current time. The subscripts represent different times. t0 , P t1 Indicates different known correction factors; Then the SO2 sensor concentration output at the current time t is: 。

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