A total VOCs detection and evaluation system based on the cruise method

Abstract

The present invention relates to the field of air sampling for physical and chemical analysis, and in particular to a total VOCs detection and evaluation system based on a cruising method, in which a VOCs sampling device adjusts the temperature and humidity of the air sucked from each position, and obtains the VOCs content in the adjusted air; a sampling frequency is obtained according to the VOCs content prediction B1 of the next position, and the adjustment process of temperature and humidity adjustment is changed according to the sampling frequency, and the VOCs content of the next position is obtained according to the difference between the humidity and temperature in the adjusted air and the preset humidity value and the preset temperature value and B1. The present invention adaptively and dynamically changes the sampling frequency during air sampling, and at the same time improves the accuracy of obtaining the VOCs content.

Description

Technical Field

[0001] The present invention relates to the field of air sampling for physical and chemical analysis, and in particular to a VOCs total amount detection and evaluation system based on a cruise method. Background Art

[0002] VOCs (volatile organic compounds) produced by industrial sources (such as chemical plants, refineries, paint factories, etc.) generally include benzene, toluene, formaldehyde and other substances. In order to detect the total amount of VOCs emissions from industrial sources, it is necessary to sample the air and detect the VOCs content at different locations around the industrial sources; existing sampling equipment generally uses sensors mounted on drones or smart cars. The sensors come into contact with the air and directly sample and detect at each location.

[0003] Among them, the sensor used for VOCs content detection can determine the concentration of VOCs substances according to the physical and chemical properties of VOCs. For example, the photoionization detector uses ultraviolet light to irradiate VOCs, excites its electrons to generate ions, and measures the number of ions to determine the VOCs concentration; for example, the electrochemical sensor uses VOCs to undergo redox reactions on the electrode surface to generate current or potential changes to detect the concentration. When measuring VOCs, the sensors in the above-mentioned sampling equipment are easily affected by the environment (for example, by temperature and humidity), resulting in a large error in the VOCs content obtained at each location around the industrial source. In addition, if the sampling frequency of the sampling equipment is not selected appropriately, the VOCs content detection results at different locations will have no reference value. Therefore, when the existing sampling equipment samples the air at different locations around the industrial source and detects the VOCs content, there may be a situation where the detection results have no reference value and there are large errors, resulting in the inability to accurately estimate the total VOCs emissions from the industrial source. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a VOCs total amount detection and evaluation system based on a cruising method.

[0005] The present invention adopts the following technical scheme for VOCs total amount detection and evaluation system based on the cruise method:

[0006] An embodiment of the present invention provides a total VOCs detection system based on a cruising method, the system comprising: a detection device and a sampling controller; the detection device comprises a detection vehicle and a VOCs sampling device, the VOCs sampling device is installed on the detection vehicle, and is used to absorb air samples from different positions; the working process of the VOCs sampling device comprises: when the detection vehicle moves to each position, the sampling controller controls the air pump to suck air from the gas sampling port into the gas pretreatment chamber, the gas pretreatment chamber adjusts the air humidity and temperature of each position, so that the humidity and temperature reach the preset humidity value and the preset temperature value respectively, the adjusted air enters the VOCs measurement chamber, and the VOCs sensor in the VOCs measurement chamber measures the VOCs content A1 at each position;

[0007] The gas pump is installed at the connection between the gas sampling port and the gas pretreatment chamber, and at the connection between the gas pretreatment chamber and the VOCs measurement chamber;

[0008] The predicted VOCs content B1 of the next position is obtained according to the VOCs content of all positions, and the sampling frequency of the VOCs sampling device is obtained according to the difference between B1 and A1, and the sampling frequency is positively correlated with the difference between B1 and A1; the sampling controller adjusts the air humidity and temperature at the next position according to the sampling frequency change, and the differences between the humidity and temperature in the adjusted air and the preset humidity value and the preset temperature value are recorded as measurement interference errors, and the VOCs content at the next position is obtained according to B1 and the measurement interference error.

[0009] Preferably, the step of obtaining the predicted VOCs content B1 at the next location includes the following specific steps:

[0010] The sequence of VOCs contents obtained at all positions is input into the Kalman filter algorithm to obtain the predicted VOCs content B1 at the next position.

[0011] Preferably, the method of obtaining the sampling frequency of the VOCs sampling device according to the difference between B1 and A1 includes the following specific steps:

[0012] The sampling frequency F=(1+w)×F0, where F0 represents the preset initial sampling frequency, and w is positively correlated with the difference between B1 and A1.

[0013] Preferably, the calculation formula of w is as follows:

[0014]

[0015] in, It is a preset value in the interval (0, 1).

[0016] Preferably, the method for acquiring the initial sampling frequency includes:

[0017] The ratio of L meters to the speed of the detection vehicle is recorded as T0, and the initial sampling frequency F0=1 / T0, where L is the preset distance.

[0018] Preferably, the gas pretreatment chamber adjusts the air humidity and temperature at each position so that the humidity and temperature reach a preset humidity value and a preset temperature value respectively, including the following specific steps:

[0019] The preset humidity value and the preset temperature value are recorded as h0 and t0 respectively;

[0020] The sampling controller uses the PID algorithm to adjust the temperature of the air to t0, and uses the PID algorithm to adjust the humidity of the air to h0.

[0021] Preferably, the adjustment process of the sampling controller when adjusting the air humidity and temperature at the next position according to the sampling frequency change includes the following specific steps:

[0022] When F is greater than F0, let w1=F / F0, and when F is less than or equal to F0, let w1=0; after the detection vehicle starts moving from the current position for T time, it reaches the next position of the current position, and the next position is recorded as NP;

[0023] The PID algorithm includes a KP parameter, and the KP parameter in the PID algorithm is increased by w1-1 times. For the air sucked into the gas pretreatment chamber at the NP, the humidity and temperature of the air are adjusted to t0 and h0 using the PID algorithm;

[0024] Wherein F0 represents the preset initial sampling frequency, and F represents the sampling frequency of the VOCs sampling device.

[0025] Preferably, the specific steps of obtaining the measurement interference error are as follows:

[0026] The humidity and temperature of the conditioned air are recorded as h and t; the preset humidity value and the preset temperature value are recorded as h0 and t0 respectively;

[0027] make , ;Measurement interference error b=(at+ah) / 2.

[0028] Preferably, the VOCs content at the next position is obtained according to B1 and the measurement interference error, and the specific formula included is as follows:

[0029] The VOCs content of the next location is A2=b×B1+(1-b)×C1;

[0030] Where b represents the measurement interference error;

[0031] C1 means: when the detection vehicle moves to the next position, the air sucked into the gas pretreatment chamber is conditioned and then enters the VOCs measurement chamber, and the VOCs sensor in the VOCs measurement chamber reads the VOCs observed value.

[0032] An embodiment of the present invention further provides a VOCs total amount assessment system based on a cruising method, comprising the above-mentioned VOCs total amount detection system based on a cruising method, wherein the VOCs total amount assessment system further comprises an assessment module, wherein the assessment module inputs the VOCs content of all locations and the meteorological data of all locations into a neural network, and the neural network outputs the pollution level of each VOCs emission source; the pollution level of the VOCs emission source is used as the assessment result;

[0033] The meteorological data includes air temperature, air humidity, wind speed and wind direction at each location.

[0034] The beneficial effects of the technical solution of the present invention are:

[0035] The VOCs sampling device of the present invention adjusts the humidity and temperature of the air sucked at each position, and adjusts the temperature and humidity to preset temperature and humidity values, thereby avoiding the problem of different errors in the VOCs content at different positions due to different temperatures and humidities at different positions (at different times);

[0036] Furthermore, the present invention obtains the sampling frequency of the VOCs sampling device through the difference between B1 and A1, so that when air sampling is performed at the next position and subsequent positions, the sampling time interval can be adaptively changed according to the VOCs content, thereby obtaining VOCs content information with more reference value.

[0037] Furthermore, in the present invention, the sampling controller adjusts the air humidity and temperature at the next position according to the sampling frequency change. The difference between the humidity and temperature in the adjusted air and the preset humidity value and the preset temperature value is recorded as the measurement interference error. The VOCs content at the next position is obtained according to B1 and the measurement interference error. When the air is sampled according to the sampling frequency (that is, while obtaining VOCs content information with more reference value), the temperature and humidity adjustment process of the air is adjusted and changed, thereby increasing the accuracy of the VOCs content information. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention 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 only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of a detection device in a VOCs total amount detection system based on a cruise method provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of a VOCs sampling device in a VOCs total amount detection system based on a cruising method provided by an embodiment of the present invention.

[0041] In the figure: 1. Detection vehicle; 2. VOCs sampling device; 3. Gas sampling port; 4. Gas pretreatment chamber; 5. VOCs measurement chamber; 6. Exhaust port; 7. Air pump; 8. Meteorological sensor group. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of a VOCs total amount detection and evaluation system based on a cruising method proposed by the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0043] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0044] The following is a detailed description of a specific scheme of a VOCs total amount detection and evaluation system based on a cruise method provided by the present invention in conjunction with the accompanying drawings.

[0045] Embodiment 1:

[0046] Embodiment 1 provides a VOCs total amount detection system based on a cruising method, the system comprising: a detection device and a sampling controller.

[0047] like Figure 1As shown, the detection equipment includes a detection vehicle 1 and a VOCs sampling device 2. The VOCs sampling device 2 is installed on the detection vehicle 1. The detection vehicle 1 is a remote-controlled intelligent vehicle. In other embodiments, an unmanned intelligent vehicle can be used as the detection vehicle 1, or a manually driven vehicle can be used as the detection vehicle 1. This embodiment does not make specific limitations.

[0048] It should also be noted that VOCs include a variety of components. This embodiment is described using the detection of formaldehyde and benzene as an example. Other embodiments may detect VOCs of other components.

[0049] like Figure 2 As shown, the VOCs sampling device 2 includes a gas sampling port 3, a gas pretreatment chamber 4, a VOCs measuring chamber 5, and an exhaust port 6; the gas sampling port 3 is connected to the gas pretreatment chamber 4, the gas pretreatment chamber 4 is connected to the VOCs measuring chamber 5, and the VOCs measuring chamber 5 is connected to the exhaust port 6; wherein an air pump 7 is installed at the connection between the gas sampling port 3 and the gas pretreatment chamber 4, the connection between the gas pretreatment chamber 4 and the VOCs measuring chamber 5, and the connection between the VOCs measuring chamber 5 and the exhaust port 6.

[0050] The gas pretreatment chamber 4 is provided with a temperature regulating device and a humidity regulating device, as well as a temperature sensor and a humidity sensor, which can adjust the temperature and humidity of the air respectively. A VOCs sensor is installed in the VOCs measuring chamber 5. The VOCs sensor used in this embodiment is a photoionization detector. Other types of sensors can be used in other embodiments, which will not be described in detail in this embodiment.

[0051] The working principle of the detection device and the sampling controller in this embodiment is:

[0052] The detection vehicle 1 moves at a constant speed along a predetermined trajectory around the industrial source. In this embodiment, it moves at a speed of 2 meters per second. In this embodiment, the position of the detection vehicle 1 is recorded once after every L meters of movement. This embodiment is described using L=10 as an example. In other embodiments, L can be set to other values, which are not specifically limited in this embodiment.

[0053] This embodiment uses the GPS device installed on the detection vehicle 1 to obtain the position of the detection vehicle 1. After the detection vehicle 1 moves to a position each time (that is, after each movement of L meters), the meteorological sensor group 8 on the detection vehicle 1 is used to obtain the air temperature, air humidity, wind speed and wind direction at each position, wherein the meteorological sensor group 8 includes: a temperature sensor, a humidity sensor, a wind speed and wind direction sensor.

[0054] At the same time, at each position, the air pump 7 in the VOCs sampling device 2 draws a portion of air from the gas sampling port 3 under the control of the sampling controller (i.e., performs an air sampling), and this portion of air enters the gas pretreatment chamber 4. The sampling controller controls the temperature adjustment device and the humidity adjustment device to adjust the temperature and humidity of the air in the gas pretreatment chamber 4. In this embodiment, the temperature and humidity of the air are adjusted to t0 and h0, respectively. This embodiment is described by taking t0=30 degrees Celsius and h0=50% as an example. Other embodiments may set t0 and h0 to other values, which are not specifically limited in this embodiment.

[0055] As an example, the method of adjusting the temperature and humidity of air to t0 and h0 respectively includes:

[0056] The sampling controller uses the PID algorithm to adjust the temperature of the air to t0, and the sampling controller uses the PID algorithm to adjust the humidity of the air to h0. The PID algorithm controls the temperature control device and the humidity control device through three parameters: proportional control (KP), integral control (KI), and differential control (KD), so that the temperature and humidity gradually approach and are equal to t0 and h0. The PID algorithm is well known, and the three parameters of the PID algorithm can be obtained by manual setting. The specific process is also well known, and this embodiment will not be described in detail.

[0057] As another example, the method of adjusting the temperature and humidity of air to t0 and h0 includes:

[0058] The temperature and humidity of the air are recorded as t1 and h1, and f(t1)=(t1-t0) / t0, f(h1)=(h1-h0) / h0 are set. Then the temperature and humidity of the air are increased or decreased by f(t1)×100% and f(h1)×100% through the temperature control device and the humidity control device. When f(t1) and f(h1) are greater than or equal to 0, the temperature and humidity are increased; when f(t1) and f(h1) are less than 0, the temperature and humidity are decreased. Then (for example, after an interval of 1 second), the temperature and humidity of the air are read again and recorded as t1 and h1, and f(t1)=(t1-t0) / t0, f(h1)=(h1-h0) / h0 are set again, and the above process is repeated until f(t1) and f(h1) are equal to 0, or approach 0 (for example, when f(t1) and f(h1) are less than 0.1, they are considered to be approaching 0 respectively). It should be noted that the detection vehicle 1 also stops repeating the above process when it moves to the next position.

[0059] Furthermore, when the temperature and humidity of the air are adjusted to t0 and h0, or when the detection vehicle 1 moves to the next position, the sampling controller controls the air pump 7 so that the air with adjusted temperature and humidity enters the VOCs measurement chamber 5. The VOCs sensor in the VOCs measurement chamber 5 measures the VOCs content in the air, which is recorded as the VOCs content at each position.

[0060] Then the sampling controller controls the air pump 7 to exhaust the air in the VOCs measurement chamber 5 from the exhaust port 6.

[0061] It should be noted that the purpose of adjusting the temperature and humidity of the air to t0 and h0 is: considering that the measurement results of the VOCs sensor will be affected by temperature and humidity, adjusting the temperature and humidity to t0 and h0 can ensure that the VOCs content at each location is measured at the same temperature and humidity, thereby avoiding the problem of errors in the VOCs content at different locations due to different temperatures and humidities at different locations (at different times).

[0062] So far, according to the above method, the detection vehicle 1 can obtain the VOCs content of each position every time it passes a position. After obtaining the VOCs content of several positions (for example, 10 positions), all VOCs contents obtained on each predetermined trajectory constitute a time series sequence; in other words, for the current position after several positions, after the VOCs content of the current position is obtained, the VOCs content of all positions constitutes a time series sequence, which is recorded as the VOCs sequence of the current position;

[0063] The VOCs sequence at the current position is used to predict the VOCs content at the next position, which is recorded as the predicted VOCs content B1 at the next position.

[0064] As an example, the VOCs sequence at the current position is used to predict the VOCs content at the next position (i.e., B1), including the following methods:

[0065] The position coordinates, VOCs content and time of obtaining the VOCs content of the first position on the predetermined trajectory are used as the state vector V0, and the VOCs sequence of the current position is input into the Kalman filter algorithm to obtain the VOCs content of the next position, and the initial state vector of the Kalman filter algorithm is set to V0. The specific principle of the Kalman filter algorithm is well known, and the specific principle and use method thereof are not described in detail in this embodiment. In other embodiments, the Kalman filter algorithm can be replaced by an extended Kalman filter algorithm or an unscented Kalman filter algorithm.

[0066] In other embodiments, an LSTM neural network may be used to predict the VOCs content at the next location based on the VOCs sequence at the current location. The LSTM neural network is also a well-known technology, and this embodiment will not go into details about its principles, network structure, and training methods.

[0067] Furthermore, the VOCs content at the current position is recorded as A1, and the sampling frequency of the VOCs sampling device 2 is obtained according to the difference between B1 and A1.

[0068] The sampling frequency is used to indicate the number of times the VOCs sampling device 2 absorbs air samples per second after the next position, or the sampling frequency can also be expressed as: the sampling time interval of each air sampling by the VOCs sampling device 2 thereafter.

[0069] If the difference between B1 and A1 is large, it means that the actual VOCs content of the next location and its surrounding area is difficult to predict, or that the actual VOCs content of the next location and its surrounding area will change significantly. Therefore, when the difference between B1 and A1 is large, the sampling frequency needs to be increased to ensure that the VOCs sampling device 2 can quickly sample the air at the next location and the subsequent locations (that is, shorten the time interval for air sampling), thereby obtaining more valuable VOCs content information;

[0070] If the difference between B1 and A1 is small, it either means that the actual VOCs content of the next position and its surrounding area is predictable, or that the actual VOCs content of the next position and its surrounding area does not change much. Therefore, when the difference between B1 and A1 is small, it is necessary to reduce the sampling frequency to ensure that the VOCs sampling device 2 increases the time interval of air sampling when sampling air at the next position and the subsequent positions, thereby avoiding obtaining too much VOCs content information that has no reference value.

[0071] As an example, the method for obtaining the sampling frequency of the VOCs sampling device 2 according to the difference between B1 and A1 includes:

[0072] The sampling frequency F=(1+w)×F0, where F0 represents the preset initial sampling frequency. The initial sampling frequency represents the time interval when the VOCs sampling device 2 performs air sampling without considering the different VOCs contents at different positions. In this embodiment, the ratio of L to the movement speed of the detection vehicle 1 is used as the time interval, recorded as T0, that is, F0=1 / T0. At this time, F0 means that air sampling is performed once every interval T0.

[0073] w represents the adjustment factor of the initial sampling frequency, and w is positively correlated with the difference between B1 and A1.

[0074] As an example, ,in season This formula can increase the sampling frequency when the difference between B1 and A1 is large, and keep the sampling frequency unchanged when the difference between B1 and A1 is small.

[0075] As another example, This formula can increase the sampling frequency when the difference between B1 and A1 is large, and reduce the sampling frequency when the difference between B1 and A1 is small.

[0076] This embodiment uses For example, in other embodiments, It is set to other values ​​in the interval (0, 1), which is not specifically limited in this embodiment.

[0077] At this point, the sampling frequency F is obtained. It should be noted that since VOCs contain multiple components, such as formaldehyde and benzene, the above method can be used to obtain a sampling frequency F for each component. In this embodiment, the sampling frequencies F of all components are averaged as the final sampling frequency F, and the final sampling frequency F is used for subsequent calculation and analysis.

[0078] Let T = 1 / F, then T represents the time interval for air sampling at the next location and thereafter.

[0079] Specifically, after obtaining the VOCs content A1 at the current position, the detection vehicle 1 moves for T time and then performs an air sampling (that is, it reaches the next position after T time, and the next position is recorded as NP). The air at NP is sucked into the gas pretreatment chamber 4 by the VOCs sampling device 2, and the gas pretreatment chamber 4 adjusts the temperature and humidity of the air therein. While adjusting the temperature and humidity, the detection vehicle 1 continues to move to the next position of NP, where the next position of NP refers to the position after T time from NP.

[0080] It should be noted that in the above process of this embodiment, while adjusting the temperature and humidity, the detection vehicle 1 continues to move to the next position of the NP in order to ensure that the detection vehicle 1 can complete the predetermined trajectory as quickly as possible, so that the VOCs content at different positions on the predetermined trajectory is measured in a short time, which is convenient for the subsequent estimation of the total VOCs emissions from industrial sources. If the time to complete the predetermined trajectory is too long, the VOCs content at different positions will be measured within a long time range. Over a long period of time, the VOCs are carried away by the air, making it difficult to estimate the total VOCs emissions from industrial sources later. Further, in order to measure the VOCs content at different positions in a shorter time, the speed of the detection vehicle 1 can be set to a larger value in other embodiments.

[0081] The problem in this process is: the temperature and humidity of the air are adjusted so that the temperature and humidity are equal to t0 and h0. This adjustment process takes time. Therefore, when the detection vehicle 1 moves to the next position of NP, the temperature and humidity may not be equal to t0 and h0, which leads to errors.

[0082] This embodiment controls the adjustment process of the humidity and temperature of the air at the NP according to the sampling frequency, thereby solving the above-mentioned problem as much as possible.

[0083] As an example, the adjustment process of adjusting the humidity and temperature of the air at the NP according to the sampling frequency includes the following methods:

[0084] When the humidity and temperature of the air are adjusted as mentioned above, if the PID algorithm is used for adjustment (described above), when F is greater than F0, set w1=F / F0, and when F is less than or equal to F0, set w1=0; increase the KP parameter in the PID algorithm by w1-1 times, and then use the PID algorithm to adjust the humidity and temperature of the air at NP to t0 and h0.

[0085] The purpose of increasing the KP parameter in the PID algorithm by w1-1 times is to make the humidity and temperature of the air approach t0 and h0 quickly when adjusting.

[0086] As another example, the adjustment process of adjusting the humidity and temperature of the air at the NP according to the sampling frequency includes the following method:

[0087] When adjusting the humidity and temperature of the air, if f(t1) and f(h1) are used for adjustment (as described above), after reading the temperature and humidity t1 and h1 of the air, f1(t1)=w1×(t1-t0) / t0 and f1(h1)=w1×(h1-h0) / h0 are set. Then the temperature and humidity of the air are increased or decreased by f1(t1)×100% and f2(h1)×100% through the temperature adjustment device and the humidity adjustment device. Then the temperature and humidity t1 and h1 of the air are read again, and the above process is repeated until f1(t1) and f1(h1) are equal to 0 or close to 0.

[0088] Furthermore, when the detection vehicle 1 moves to the next position of NP, the adjustment of the humidity and temperature of the air is stopped, and the humidity and temperature of the air at this time are recorded, recorded as t and h, and the air in the gas pretreatment chamber 4 is pumped into the VOCs measurement chamber 5. In the VOCs measurement chamber 5, the VOCs content is read by a VOCs sensor, recorded as the VOCs observation value, recorded as C1, which represents the observation result of the VOCs content at NP. Since t and h may not be equal to t0 and h0, the VOCs observation value C1 may have a measurement error.

[0089] Will The difference between the temperature of the conditioned air and the preset temperature value t0 is recorded as It is recorded as the difference between the humidity in the conditioned air and the preset humidity value h0.

[0090] The larger at and ah are, the more the detection vehicle 1 moves to the next position of NP, the more the adjusted temperature and humidity deviate from t0 and h0, and the larger the measurement error of the VOCs observation quantity C1 is at this time; the smaller at and ah are, the smaller the detection vehicle 1 moves to the next position of NP, the closer the adjusted temperature and humidity are to t0 and h0, and the smaller the measurement error of the VOCs observation quantity C1 is at this time.

[0091] In this embodiment, A2=b×B1+(1-b)×C1 is set, and A2 is used as the VOCs content at the NP, where b represents the measurement interference error, and b=(at+ah) / 2.

[0092] The larger at and ah are, the larger the measurement interference error b in the above formula is, that is, the VOCs observation amount C1 has obvious errors. At this time, the VOCs content A2 at the NP pays more attention to the VOCs predicted content B1 at the NP; the smaller at and ah are, the smaller b is in the above formula, that is, the VOCs observation amount C1 does not have obvious errors. At this time, the VOCs content A2 at the NP pays more attention to the VOCs observation amount C1 at the NP.

[0093] In the above-mentioned adjustment process of adjusting the humidity and temperature of the air at NP according to the sampling frequency in this embodiment, the VOCs observed value C1 at NP is adjusted according to at, ah and B1 to obtain the VOCs content A2 in the air at NP, thereby improving the accuracy of A2.

[0094] In summary, the present embodiment includes the following steps: (1) obtaining the VOCs content A1 at the current position and the predicted VOCs content B1 at the next position; (2) obtaining the sampling frequency according to the difference between A1 and B1, sampling air at the next position of the current position (i.e., NP), and the detection vehicle 1 moves from NP to the next position of NP according to the sampling frequency. In this process, the humidity and temperature of the air at NP are adjusted according to the sampling frequency; (3) when the detection vehicle 1 arrives at the next position of NP, the VOCs content A2 of NP is obtained according to the difference between the humidity and temperature in the adjusted air and the preset humidity value and the preset temperature value, as well as B1.

[0095] Then the following working method of the detection equipment is:

[0096] Take NP as the current position and re-mark the position after the current position as NP;

[0097] At this time, the VOCs content at the current position is A2, and the VOCs content at the next position after the current position is predicted, recorded as B2. The specific process is the same as above (1);

[0098] Then, the sampling frequency is obtained again according to the difference between A2 and B2, which represents the time interval of air sampling after the next position of the current position (i.e., NP); the air is sampled at the next position of the current position (i.e., NP), and the detection vehicle 1 moves from NP to the next position of NP according to the sampling frequency. In this process, the adjustment process of adjusting the air humidity and temperature at NP according to the sampling frequency is the same as the above (2);

[0099] When the detection vehicle 1 arrives at the next position of the NP, the VOCs content at the NP is obtained according to the difference between the humidity and temperature in the conditioned air and the preset humidity value and the preset temperature value, and B2, which is recorded as A3; the specific process is the same as the above (3);

[0100] Then, NP is taken as the current position, and the next position of the current position is re-marked as NP; and the above process is repeated until the detection vehicle 1 completes the predetermined trajectory.

[0101] In the above process, the sampling frequency of the VOCs sampling device 2 is continuously adjusted, and the humidity and temperature of the air are adjusted based on the sampling frequency control, and the VOCs content at each position is further obtained.

[0102] In this embodiment, the sum of the VOCs contents at all locations on the predetermined trajectory is taken as the total VOCs amount of the industrial source.

[0103] This process draws samples at different positions, so that the VOCs content collected at different positions has reference value while ensuring the accuracy of the VOCs content. Furthermore, this embodiment allows the detection vehicle 1 to obtain more reference-valued and accurate VOCs content in the shortest possible time.

[0104] Embodiment 2:

[0105] The difference between this embodiment and the first embodiment is that another method for obtaining the VOCs content A2 at the NP is given:

[0106] Still let b = (at + ah) / 2. The larger the b is, the larger the measurement error of the VOCs observation quantity C1 at the NP is, and the smaller the b is, the smaller the measurement error of the VOCs observation quantity C1 at the NP is.

[0107] In this embodiment, the measurement error of C1 is recorded as e1, and e1 is positively correlated with b. As an example, let e1=b×|C1-B1|, wherein |C1-B1| represents the difference between the observed VOCs C1 at the NP and the predicted VOCs content B1 at the NP. In this embodiment, the difference is used to represent the total error of VOCs at the NP. The total error includes both the measurement error and the prediction error. The prediction error refers to the error when obtaining the predicted VOCs content B1. The error is recorded as e2, and e2 is negatively correlated with e1. In this embodiment, let e2=|C1-B1|-e1.

[0108] It should be noted that the method for predicting the VOCs content B1 in this implementation is: input the VOCs sequence at the current position into the Kalman filter algorithm to obtain the VOCs content at the next position (i.e., B1). The Kalman filter algorithm is a well-known technology, which includes a state prediction formula and a state update formula. In this embodiment, e2 is added to the state prediction formula to reduce the prediction error of the Kalman filter algorithm. Then the VOCs sequence at the current position is re-input into the Kalman filter algorithm to obtain the VOCs content at the next position. The result is recorded as B11, and then the VOCs content at NP is set to A2=b×B11+(1-b)×C1.

[0109] Compared with the first embodiment, this embodiment performs error correction on the Kalman filter algorithm, updates and corrects B1 (that is, updates and corrects B1 to B11), thereby further improving the accuracy of A2.

[0110] Embodiment three:

[0111] The temperature regulating device includes a structure as follows: a thermal resistance wire, the resistance wire is connected to a 5-volt power supply, a controllable switch is connected between the resistance wire and the power supply, and the sampling controller controls the heating time of the thermal resistance wire by controlling the closing time of the controllable switch, that is, the sampling controller controls the amount of air temperature rise by controlling the closing time of the controllable switch. In addition, the temperature regulating device also includes a heat pipe, which conducts the heat of the air in the gas pretreatment chamber 4 to the outside of the gas pretreatment chamber 4, and the heat pipe outside the gas pretreatment chamber 4 is connected to a heat dissipation fan, and the sampling controller controls the amount of air temperature drop by controlling the speed of the heat dissipation fan.

[0112] In other embodiments, the temperature adjustment device may be configured as other structures. Since the temperature adjustment device is a commonly used device, this embodiment does not specifically limit its structure.

[0113] The humidity regulating device in this embodiment includes a humidifier and a dehumidifier. The sampling controller adjusts the humidity by controlling the humidifier and the dehumidifier. In other embodiments, a constant humidity chamber can be used directly. The humidity regulating device is also a commonly used device, and this embodiment does not specifically limit its structure.

[0114] Embodiment 4:

[0115] The method in which the sampling controller controls the air pump 7 to allow air to pass through the gas pretreatment chamber 4 and the VOCs determination chamber 5 is as follows:

[0116] The air pump 7 installed at the connection between the gas pretreatment chamber 4 and the gas sampling port 3 is recorded as the first air pump, the air pump 7 installed at the connection between the gas pretreatment chamber 4 and the VOCs measurement chamber 5 is recorded as the second air pump, and the air pump installed at the connection between the VOCs measurement chamber 5 and the exhaust port 6 is recorded as the third air pump.

[0117] In this embodiment, when any of the air pumps 7 is not started, no gas is circulated. At the same time, air pressure sensors are installed in the gas pretreatment chamber 4 and the VOCs measurement chamber 5 to obtain air pressure. At the same time, the volume of the gas pretreatment chamber 4 and the VOCs measurement chamber 5 is the same.

[0118] The working process of all air pumps 7 is: start the first air pump, the second air pump and the third air pump. Allow air to flow into the gas pretreatment chamber 4, then turn off the first air pump and the second air pump, so that the gas pretreatment chamber 4 is a closed space, and the temperature and humidity of the air in the gas pretreatment chamber 4 are adjusted. While adjusting, start the third air pump to discharge the air in the VOCs measurement chamber 5. In this embodiment, when the air pressure is less than 0.1 standard atmospheric pressure, the air is considered to be emptied. After the adjustment is completed, turn off the first air pump and the third air pump, turn on the second air pump, and empty the air in the gas pretreatment chamber 4, all of which are discharged into the VOCs measurement chamber 5, and perform VOCs measurement.

[0119] Embodiment five:

[0120] All of the above-mentioned embodiments obtain the VOCs content at each position on the predetermined trajectory, which has the following problems: on the one hand, the predetermined trajectory cannot cover all positions of the industrial source, so the VOCs content at all positions on the predetermined trajectory cannot obtain the VOCs emission source of the industrial source and evaluate the pollution level of each emission source; on the other hand, the VOCs content at all positions is not obtained at the same time, and the VOCs at some positions may be lost and not detected; in short, the VOCs at all positions on the predetermined trajectory cannot be used to accurately obtain the VOCs emission source of the industrial source and evaluate the pollution level of each emission source.

[0121] In this embodiment, a VOCs total amount assessment system based on a cruising method is provided, and the system integrates the above-mentioned VOCs total amount detection system based on a cruising method.

[0122] In a VOCs total amount detection system based on the navigation method in Example 1, the VOCs content of each position on the predetermined trajectory is obtained, and the meteorological input data of each position is also recorded. The meteorological input data includes air temperature, air humidity, wind speed and wind direction. The VOCs content (that is, VOCs concentration), the time of air sampling and the meteorological input data of all positions on the predetermined trajectory are taken as a sample. Each VOCs emission source is manually marked according to all samples on the set trajectory, and a pollution level is manually assigned to each VOCs emission source. The pollution level includes 0, 1, 2, ... 9 ten levels. The pollution level indicates the degree of air pollution caused by VOCs emission. The larger the pollution level, the more serious the air pollution. The marked VOCs emission source and pollution level are used as labels for the sample.

[0123] For the predetermined trajectories around multiple industrial sources, multiple samples are obtained correspondingly after air sampling on these predetermined trajectories, and all samples and their labels constitute the data set.

[0124] The evaluation system includes an evaluation module, which uses a data set to train a neural network. The first three layers of the neural network are fully connected neural networks, and from the fourth layer to the last layer, a convolutional neural network with an Encoder-Decoder structure (such as a DeepLabV3 network) is used. The input of the neural network is the sample corresponding to each predetermined trajectory, and the output is each VOCs emission source and the pollution level of each VOCs emission source. The neural network is trained using the above-mentioned data set, and the loss function used during training is the cross entropy loss function, and the neuron update method is the stochastic gradient descent method.

[0125] For a new industrial source, a VOCs total amount detection system based on a cruising method in Example 1 is used to obtain the VOCs content of all positions on a predetermined trajectory around the industrial source, and obtain samples corresponding to the predetermined trajectory. The samples are input into the trained neural network to obtain the VOCs emission source of the new industrial source and the pollution level of the VOCs emission source. The pollution level of the VOCs emission source is used as the VOCs emission assessment result of the industrial source. When there is an emission source with a pollution level greater than TH, all production and manufacturing activities in the emission source are stopped. This embodiment is described using TH=5 as an example. In other embodiments, TH can be set to other values, which are not specifically limited in this embodiment.

[0126] The above-mentioned neural network technology and neural network training method are well known and will not be described in detail in this embodiment.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A VOCs total amount detection system based on a cruise method, the system comprising: A detection device and a sampling controller; the detection device comprises a detection vehicle (1) and a VOCs sampling device (2); the VOCs sampling device (2) is installed on the detection vehicle (1) and is used to absorb air samples from different positions; the characteristic is that the working process of the VOCs sampling device (2) comprises: when the detection vehicle (1) moves to each position, the sampling controller controls the air pump (7) to suck air from the gas sampling port (3) into the gas pretreatment chamber (4); the gas pretreatment chamber (4) adjusts the air humidity and temperature at each position so that the humidity and temperature reach a preset humidity value and a preset temperature value respectively; the adjusted air enters the VOCs measurement chamber (5); the VOCs sensor in the VOCs measurement chamber (5) measures the VOCs content A1 at each position; The air pump (7) is installed at the connection between the gas sampling port (3) and the gas pretreatment chamber (4), and at the connection between the gas pretreatment chamber (4) and the VOCs measurement chamber (5); The predicted VOCs content B1 of the next position is obtained based on the VOCs content of all positions, and the sampling frequency of the VOCs sampling device (2) is obtained based on the difference between B1 and A1, and the sampling frequency is positively correlated with the difference between B1 and A1; the sampling controller adjusts the air humidity and temperature at the next position according to the sampling frequency change, and the difference between the humidity and temperature in the adjusted air and the preset humidity value and the preset temperature value is recorded as the measurement interference error, and the VOCs content of the next position is obtained based on B1 and the measurement interference error.

2. According to claim 1, a VOCs total amount detection system based on the cruise method is characterized in that: The specific steps of obtaining the predicted VOCs content B1 at the next location are as follows: The sequence of VOCs contents obtained at all positions is input into the Kalman filter algorithm to obtain the predicted VOCs content B1 at the next position.

3. According to claim 1, a VOCs total amount detection system based on the cruise method is characterized in that: The method of obtaining the sampling frequency of the VOCs sampling device (2) according to the difference between B1 and A1 includes the following specific steps: The sampling frequency F=(1+w)×F0, where F0 represents the preset initial sampling frequency, and w is positively correlated with the difference between B1 and A1.

4. According to claim 3, a VOCs total amount detection system based on the cruise method is characterized in that: The calculation formula of w is as follows: in, It is a preset value in the interval (0, 1).

5. According to claim 3, a VOCs total amount detection system based on the cruise method is characterized in that: The method for obtaining the initial sampling frequency includes: The ratio of L meters to the speed of the detection vehicle (1) is recorded as T0, and the initial sampling frequency F0=1 / T0, where L is the preset distance.

6. According to claim 1, a VOCs total amount detection system based on the cruise method is characterized in that: The gas pretreatment chamber (4) adjusts the air humidity and temperature at each position so that the humidity and temperature reach a preset humidity value and a preset temperature value respectively, and the specific steps include the following: The preset humidity value and the preset temperature value are recorded as h0 and t0 respectively; The sampling controller uses the PID algorithm to adjust the temperature of the air to t0, and uses the PID algorithm to adjust the humidity of the air to h0.

7. A VOCs total amount detection system based on the cruise method according to claim 6, characterized in that: The specific steps of the adjustment process when the sampling controller adjusts the air humidity and temperature at the next position according to the sampling frequency change are as follows: When F is greater than F0, w1=F / F0 is set, and when F is less than or equal to F0, w1=0 is set; the detection vehicle (1) starts to move from the current position and arrives at the next position of the current position after T time, and the next position is recorded as NP; The PID algorithm includes a KP parameter, and the KP parameter in the PID algorithm is increased by w1-1 times. For the air sucked into the gas pretreatment chamber (4) at the NP, the humidity and temperature of the air are adjusted to t0 and h0 using the PID algorithm; Wherein F0 represents the preset initial sampling frequency, and F represents the sampling frequency of the VOCs sampling device (2).

8. According to claim 1, a VOCs total amount detection system based on the cruise method is characterized in that: The specific steps for obtaining the measurement interference error are as follows: The humidity and temperature of the conditioned air are recorded as h and t; the preset humidity value and the preset temperature value are recorded as h0 and t0 respectively; make , ;Measurement interference error b=(at+ah) / 2.

9. According to claim 1, a VOCs total amount detection system based on the cruise method is characterized in that: The VOCs content at the next position is obtained according to B1 and the measurement interference error, and the specific formula included is as follows: The VOCs content of the next location is A2=b×B1+(1-b)×C1; Where b represents the measurement interference error; C1 represents: when the detection vehicle (1) moves to the next position, the air sucked into the gas pretreatment chamber (4) is conditioned and then enters the VOCs measurement chamber (5), and the VOCs observed value read by the VOCs sensor in the VOCs measurement chamber (5).

10. A VOCs total amount assessment system based on a cruise method, comprising a VOCs total amount detection system based on a cruise method as claimed in any one of claims 1 to 9, characterized in that: The VOCs total amount assessment system also includes an assessment module, which inputs the VOCs content of all locations and the meteorological data of all locations into a neural network, and the neural network outputs the pollution level of each VOCs emission source; the pollution level of the VOCs emission source is used as the assessment result; The meteorological data includes air temperature, air humidity, wind speed and wind direction at each location.

Images