阅读说明：本技术 一种主动进气式tvoc检测仪 (Formula TVOC detector admits air voluntarily ) 是由 张英磊 徐娇 洪小伟 张邓毅 于 2020-12-28 设计创作，主要内容包括：本发明涉及一种主动进气式TVOC检测仪,包括外壳和设置在外壳内部的控制电路板,所述控制电路板上设有天线和数据通讯模块,所述外壳上设有至少一组空气流通孔,所述外壳内部设有与所述空气流通孔相连的气室、与所述气室相连通的主动进气单元以及与所述主动进气单元相连的排气通道,所述控制电路板上还包括至少部分位于所述气室内的传感器阵列模块,所述传感器阵列模块包括至少两种电化学气体传感器。本发明采用主动进气单元相比于扩散进气会更稳定,通过主动进气到气室,气流和温湿度都会更加稳定,能够有效地降低对于传感器的修正难度,具有低功耗、长寿命、较好的精度和稳定性等优点,应用范围得到极大地提升。(The invention relates to an active air intake type TVOC detector which comprises a shell and a control circuit board arranged inside the shell, wherein the control circuit board is provided with an antenna and a data communication module, the shell is provided with at least one group of air circulation holes, the shell is internally provided with an air chamber connected with the air circulation holes, an active air intake unit communicated with the air chamber and an exhaust passage connected with the active air intake unit, the control circuit board also comprises a sensor array module at least partially positioned in the air chamber, and the sensor array module comprises at least two electrochemical gas sensors. Compared with diffusion air inlet, the active air inlet unit is more stable, air flow and temperature and humidity are more stable through active air inlet to the air chamber, the correction difficulty of the sensor can be effectively reduced, the active air inlet unit has the advantages of low power consumption, long service life, better precision and stability and the like, and the application range is greatly improved.)

1. The utility model provides an initiative formula TVOC detector of admitting air, includes shell (3) and sets up control circuit board (1) inside the shell, be equipped with antenna (2) and data communication module (4) on control circuit board (1), its characterized in that: the gas sensor is characterized in that at least one group of air circulation holes (10) are formed in the shell (3), an air chamber (13) is arranged in the shell (3), the air chamber (13) is communicated with the outer side of the shell (3) through an air inlet channel (11) and an air outlet channel (14) respectively, an active air inlet unit (12) is arranged on the air inlet channel (11) or the air outlet channel (14), the air inlet channel (11) is communicated with the air circulation holes (10), the control circuit board (1) further comprises a sensor array module (6) which is at least partially located in the air chamber (13), and the sensor array module (6) comprises at least two electrochemical gas sensors.

2. The active air intake TVOC detector of claim 1, wherein: the active air inlet type TVOC detector further comprises a temperature and humidity control module (7), wherein at least part of the temperature and humidity control module (7) is positioned in the air chamber (13).

3. The active air intake TVOC detector of claim 1 or 2, wherein: the active air intake type TVOC detector further comprises a data storage module (5).

4. The active air intake TVOC detector of claim 1, wherein: external air flow enters an air chamber (13) inside the shell (3) through the at least one group of air through holes (10) in an active suction or blowing mode, and the air flow entering the air chamber (13) is in parallel contact with an effective action surface of the sensor in the sensor array module (6).

5. The active air intake TVOC detector of claim 1, wherein: the active air inlet unit is a fan or an air pump.

6. The active air intake TVOC detector of claim 1, wherein: the shell (3) comprises a top shell (8) and a bottom shell (9), the air circulation hole (10) is located in the top shell (8), and the control circuit board (1) is installed on a clamping groove in the top shell (8).

7. The active air intake TVOC detector of claim 1, wherein: the data communication module (4) comprises one of an NB-IOT communication module, a LoRa communication module, a Bluetooth communication module, a WIFI communication module and an IPV6 communication module.

8. The active air intake TVOC detector of claim 1, wherein: the active air intake type TVOC detector further comprises a battery or solar power supply device connected with the control circuit board (1), and the power supply input voltage of the control circuit board (1) is 5-24V.

9. The active air intake TVOC detector of claim 1, wherein: the electrochemical gas sensor comprises at least two solid electrolyte sensors in alkane, alkene, benzene and alcohol.

10. The active air intake TVOC detector of claim 9, wherein: the sensor array module (6) further comprises an oxygen sensor, an ethanol sensor and a temperature and humidity sensor for correction.

Technical Field

The invention relates to a gas detection device, in particular to an active air intake type TVOC detector.

Background

The world health organization (WHO,1989) defines Total Volatile Organic Compounds (TVOC) as a general term for volatile organic compounds having a melting point below room temperature and a boiling point between 50-260 ℃. With the continuous development of urbanization, the discharge amount of VOCs is gradually increased, and the discharge amount of VOCs becomes one of the main pollutants of urban air pollution in recent years. The types of VOCs are many (more than 300 are most common), the number of related industries and enterprises is large, the discharge condition is complex, the supervision is very difficult, and the monitoring and the detection become a key service for restricting the treatment of the VOCs at present.

In the petrochemical industry, in particular, the concentration level of VOCs is high, wherein various compounds such as alkane, alkene, alkyne and aromatic hydrocarbon have high concentration, and the method is one of industrial sources which have important contribution to VOCs in the atmosphere. Early studies of the results of resolving specific sources in the petrochemical industry revealed that alkanes are predominantly n-butane, 2-methylbutane, 2-methylpentane and 2, 2-dimethylpentane, and these C4-C7 alkanes are the major components of the volatile emissions of lubricating oils. The aromatic hydrocarbon substances mainly comprise alkylbenzene, mainly comprise n-propylbenzene, o-xylene, m-methylethylbenzene and toluene. The alkane and arene substances are mainly caused by the production of lubricating oil and alkylbenzene in three chemical fields. In the olefins, the concentration of cis-2-butene and isoamylene is high, and the olefins are mainly formed by volatilization of substances such as gasoline and diesel oil. In addition, a certain acetylene component is contained. The concentration of each VOC is about 50-1000ppbC, and the typical VOCs listed above account for more than 50% of the total VOCs.

The traditional chromatographic, mass spectrometric or spectroscopic instrument has high precision and good stability, but has the problems of high price, large volume, troublesome maintenance, need of stable gas source, regular calibration and maintenance of personnel and the like, and is difficult to be applied to dense gridding distribution. In recent years, gas chromatographs developed based on flame ionization detectors have been used as standard analytical methods for detecting VOCs in the atmosphere because they can separate organic components from the atmosphere. For example, patent documents such as "volatile organic compound continuous detector" with publication number CN101609072A, and "optimization and calibration method for ambient air non-methane total hydrocarbon online detection instrument" with publication number CN108982728A, but since the operation of the VOC monitoring device based on FID is complicated, professional operation is required during the operation process, and frequent calibration and maintenance are required, which limits the application. And the test interval time is long (usually 1h of data), so that the method is difficult to be used for gridding distribution to test the atmosphere.

Other sensor-based VOCs detectors have also been developed, such as Photo Ionization Detectors (PID), but the lifetime of VOC monitoring devices based on PID sensors is typically less than 1 year, while the cost of PID sensors is high (see patent document CN103424465A intelligent PID sensor module). Meanwhile, the existing VOC testing equipment (patent document CN105388208A entitled "VOC detector in air based on PID and method for realizing remote monitoring" with publication number) based on the single sensor is difficult to meet the testing requirement of VOC multi-components in the atmosphere, and especially the accuracy of VOC testing in complex atmospheric environment and the consistency with standard instruments are difficult to meet the actual requirement.

In comparison, the sensor has the advantages of small size, simple operation, portability, low price and the like, can be used for on-site monitoring, and is considered as a substitute tool capable of being widely distributed. However, the method still has the problems of low sensitivity and stability, weak interference resistance and the like, so that the reliability is not high. Therefore, the development of the sensor which has good stability and can monitor VOCs in a classified manner has high practical significance and scientific value. The conventional TVOC detector is a sensor based on a gas sensor (PID, MEMS or electrochemical principle), and the sensors are usually calibrated by only one gas (ethanol or isobutylene) when leaving a factory, and have a correction coefficient for different gases, but in the actual measurement process, the sensors are not corrected or cannot be corrected accurately, so that the application in the complex environment in the air cannot be satisfied. In addition, in the case where the temperature and humidity in the intake structure are unstable or the airflow is also unstable, the difficulty of correction is also increased.

Therefore, development of a VOC detector with low cost, fast response and high accuracy is urgently needed.

Disclosure of Invention

The invention aims to solve the problems and provides an active air intake type TVOC detector which mainly senses alkane, alkene and aromatic hydrocarbon according to a source analysis result so as to improve sensing accuracy, effectively reduces the difficulty in correcting the sensor through structural arrangement, and obtains a VOC monitoring device with low cost, quick response and high accuracy.

In order to achieve the purpose, the invention provides an active air intake type TVOC detector which comprises a shell and a control circuit board arranged inside the shell, wherein the control circuit board is provided with an antenna and a data communication module, the shell is provided with at least one group of air circulation holes, the shell is internally provided with an air chamber, the air chamber is respectively communicated with the outer side of the shell through an air intake channel and an air exhaust channel, the air intake channel or the air exhaust channel is provided with an active air intake unit, the air intake channel is communicated with the air circulation holes, the control circuit board further comprises a sensor array module at least partially positioned in the air chamber, and the sensor array module comprises at least two electrochemical gas sensors.

Preferably, the active air intake type TVOC detector further includes a temperature and humidity control module, and the temperature and humidity control module is at least partially located in the air chamber.

Preferably, the active air intake type TVOC detector further includes a data storage module.

Preferably, the external air flow enters the air chamber inside the shell through the at least one group of air through holes in an active suction or blowing mode, and the air flow entering the air chamber is in parallel contact with the effective active surface of the sensor in the sensor array module.

Preferably, the housing comprises a top shell and a bottom shell, the air circulation hole being located on the top shell. The control circuit board is arranged on the clamping groove in the top shell.

Preferably, the active air intake unit is a fan or an air pump.

Preferably, the data communication module comprises one of an NB-IOT communication module, an LoRa communication module, a bluetooth communication module, a WIFI communication module, and an IPV6 communication module.

Preferably, the active air intake type TVOC detector further comprises a battery or solar power supply device connected with the control circuit board, and the power supply input voltage of the control circuit board is 5-24V.

Preferably, the electrochemical gas sensor comprises at least two solid electrolyte sensors of alkanes, alkenes, benzene, alcohols.

Preferably, the sensor array module further comprises an oxygen sensor, an ethanol sensor and a temperature and humidity sensor for correction.

Based on the technical scheme, the invention has the advantages that:

the active air intake type TVOC detector can be used for monitoring and evaluating the air quality of indoor and outdoor environments, consists of a multi-path solid polymer electrochemical sensor, can measure various gases capable of being chemically decomposed, and has the advantages of low power consumption, long service life, good precision and stability and the like. The multi-channel sensor array module can be used for detecting more gases, and the application range is greatly improved. Compared with diffusion air intake, the active air intake unit adopting the form of a fan or an air pump and the like is more stable, and the air flow and the temperature and humidity are more stable through actively feeding air into the air chamber, so that the correction difficulty of the sensor can be effectively reduced.

Furthermore, the invention adopts the benzene, alkane and olefin sensors which are designed independently in a targeted manner, and introduces the oxygen and alcohol sensors for correction, so that the reading of the sensors can be more accurate. Meanwhile, the sensor is designed with low power consumption, so that the personnel maintenance and the energy consumption are greatly reduced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

fig. 1 is a schematic diagram of an internal structure of an active air intake type TVOC detector;

fig. 2 is an explosion diagram of the TVOC detector with active air intake.

Detailed Description

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

The invention provides an active air intake type TVOC detector, as shown in FIGS. 1-2, wherein a preferred embodiment of the invention is shown.

As shown in fig. 1, the active air intake TVOC detector includes a housing 3 and a control circuit board 1 disposed inside the housing, the control circuit board 1 is provided with an antenna 2 and a data communication module 4, the housing 3 is provided with at least one set of air circulation holes 10, the housing 3 is provided with an air chamber 13 inside, the air chamber 13 is communicated with the outside of the housing 3 through an air intake passage 11 and an air exhaust passage 14, the air intake passage 11 or the air exhaust passage 14 is provided with an active air intake unit 12, the air intake passage 11 is communicated with the air circulation holes 10, the control circuit board 1 further includes a sensor array module 6 at least partially disposed in the air chamber 13, and the sensor array module 6 includes at least two types of electrochemical gas sensors.

External air flow enters an air chamber 13 inside the shell 3 through the at least one group of air through holes 10 in an active suction or blowing mode, and the air flow entering the air chamber 13 is in parallel contact with an effective action surface of the sensor in the sensor array module 6. The air chamber 13 is communicated with the outer side of the shell 3 through an air inlet channel 11 and an air outlet channel 14 respectively, and a sampling air inlet passage is formed. An active air inlet unit 12 is arranged on the air inlet channel 11 or the air outlet channel 14, and the active air inlet unit is a fan or an air pump. The active air inlet unit adopting the form of a fan or an air pump and the like is more stable than diffusion air inlet, air flow and temperature and humidity are more stable when the active air inlet unit actively enters the air chamber 13, and the difficulty in correcting the sensor can be effectively reduced.

As shown in fig. 2, the housing 3 includes a top case 8 and a bottom case 9, and the air flow hole 10 is located on the top case 8. The control circuit board 1 is installed on a card slot in the top case 8. The control circuit board 1 is a core main control board of the whole detection instrument and adopts a low-power-consumption design. The main control board can adopt stm32l151 series low-power consumption series single-chip microcomputer, has a plurality of pins and complete peripheral equipment, and meets the functions of processing temperature and humidity influence, correcting multiple sensors, controlling the Internet of things module and the like.

In the present invention, the main hardware usage of the control circuit board 1 is as follows:

(1) 2-way DAC: the voltage difference is designed to make the sensor more sensitive and stable.

(2)6+1 ADC: the output voltage of the 6+1 path of sensor is collected, 12-bit analog-to-digital conversion is carried out, and the data precision is guaranteed.

(3) The hardware IIC controls the OLED to display: the OLED is a 128 × 64 pixel screen, and is used to display data to be displayed on the system board, such as sensor values, temperature and humidity, network communication status, and the like, in real time. To reduce power consumption, the OLED is turned off by a switch.

(4) The GPIO simulates IIC to read the temperature and humidity sensor, and an SHT20 high-precision digital temperature and humidity chip is adopted, so that the temperature and humidity sensor can be used for correcting sensor data.

(5) SPI interface: control loRa thing networking communication module, the loRa module adopts SX1278, and the worker group frequency is at 433MHz, and the maximum transmission distance 10KM of spacious environment sets up solitary toggle switch for opening and closing of control loRa communication module.

(6) A serial port IOT: and the serial port is used for controlling the NB-IOT/GPRS Internet of things module.

(7) Serial port PC: and the upper computer is communicated with the computer and is used for debugging at the computer end.

(8) Serial port Demo: and (5) standby serial ports.

(9) Two LED lamps: indicating whether the data communication is normal.

Preferably, the electrochemical gas sensor comprises at least two solid electrolyte sensors of alkanes, alkenes, benzene, alcohols. On the control circuit board 1, a multi-channel sensor reading circuit is arranged, and the multi-channel sensor reading circuit comprises 1 channel of bias adjustable sensor circuit. The multi-channel sensor can distinguish different gases, correct the gases mutually and finally obtain more accurate VOC concentration. In addition, two paths of serial ports are arranged, so that a commercial and mature circuit board can be read and used as auxiliary correction, and outfield debugging is facilitated.

In the invention, the sensor circuit adopts a low-voltage and low-power consumption design, a 0V bias design of a circuit board is adjusted, the reaction current is unified, and the power consumption is reduced; the load resistance of each sensor is adjusted from 39 ohms to 10 ohms, and the sensing response speed is increased. Since the amplification circuit of the electrochemical sensor cannot be intermittently powered, the electrochemical sensor is more suitable for continuous power supply because the electrochemical sensor has a warm-up time (in the order of minutes or even longer). Preferably, the active air intake type TVOC detector further comprises a battery or solar power supply device connected to the control circuit board 1, and the power supply input voltage of the control circuit board 1 is 5-24V. In order to ensure that the detector can continuously work for one year, a solar cell panel is added to timely supplement consumed electric quantity.

The sensitivity of detection of gases at different bias voltages varies with different sensing materials. In this embodiment, a 10-channel detection instrument is designed to obtain 10 channels of sensing data, and the sensing data is corrected, compared with a standard instrument, and learned. Measuring the influence of each interference quantity on the measured quantity by using a standard instrument to obtain a calibration curve (surface); the sensor readings of each interference quantity are approximately regarded as true values and are brought into the calibration curve (surface) obtained in the last step to compensate the measured quantity.

Preferably, the data communication module 4 includes one of an NB-IOT communication module, an LoRa communication module, a bluetooth communication module, a WIFI communication module, and an IPV6 communication module. Since the NB-IOT focuses on small data size, low rate applications, the NB-IOT device power consumption can be made very small, and the device endurance can be greatly increased from the past months to years. The NB-IOT wireless communication mode can be optimized to realize real-time data transmission of the detector by comprehensively considering the operation and maintenance cost and the later use condition of the wireless communication scheme.

Preferably, the active air intake type TVOC detector further includes a data storage module 5. The data acquired by several modules are stored in the data storage module 5 and transmitted by the data transmission module 4.

Further, the active air intake type TVOC detector further comprises a temperature and humidity control module 7, wherein at least part of the temperature and humidity control module 7 is located in the air chamber 13. Preferably, the sensor array module 6 further includes a correction unit that corrects the temperature by using an oxygen sensor, an ethanol sensor, and a temperature and humidity sensor.

For temperature compensation, a calibration curve is fitted from the electric signal-temperature data, and temperature compensation is performed according to the calibration curve. For humidity correction, the static error is well eliminated by sampling and fitting a calibration curve, the sensor is packaged from the beginning of hardware, and the change of the humidity in the sensor is restrained as far as possible from the source.

The sensor array module 6 comprises at least two electrochemical gas sensors, the sensor array module 6 is composed of multiple paths of solid polymer electrochemical sensors, and cross compensation is adopted for correction. The "many-to-many" problem is solved into several "many-to-one" problems. For example: the problem of compensating toluene, ethanol and methane simultaneously is resolved as follows: (1) compensating the toluene sensor according to the output of the ethanol, methane, temperature and humidity sensors; (2) compensating the ethanol sensor according to the output of the toluene, ethanol, temperature and humidity sensors; (3) according to the output of the toluene, methane, temperature and humidity sensors, the methane sensor is compensated. Then, measuring the influence of each interference quantity on the measured quantity by using a standard instrument to obtain a calibration curve (surface); and finally, approximately considering the sensor readings of all the interference quantities as a true value, and substituting the true value into the calibration curve (surface) obtained in the last step to compensate the measured quantity. The active air intake type TVOC detector adopts the sensor array to detect TVOC in real time, is more scientific and accurate, and further improves the accuracy of the detector.

The TVOC detector using the active air intake type TVOC detector can carry out TVOC monitoring through the following steps:

1. the power supply module of the detector supplies power to the control module of the TVOC detector, and the control module acquires monitoring data of the sensor array module and/or the temperature and humidity control module;

2. the control module sends the acquired data to the data communication module 4 and the data storage module 5;

3. the data communication module 4 sends data to a relay station connected with a plurality of TVOC detectors;

4. the relay station feeds back and checks the data information received by the relay station to the control module of each TVOC detector respectively;

5. and the relay station sends the checked data information to the TVOC background, and the TVOC background feeds back and/or checks the data information to the control modules of the TVOC detectors again after being corrected.

The power supply module supplies power to the control circuit board 1 of the active air intake type TVOC detector, and the temperature and humidity control module 7 and the sensor array module 6 are arranged on the control circuit board 1. The data obtained by the modules are stored in a data storage module 5 and are transmitted to the relay station through a data transmission module 4, the relay station checks the transmitted data once at intervals to confirm that the data are received, and if the data are not received, an instruction for sending the data again is sent to the control module. And the relay station sends the complete data to the PC terminal. The PC terminal further corrects the data and feeds back an algorithm on the control module to finish detection.

The active air intake type TVOC detector can be used for monitoring and evaluating the air quality of indoor and outdoor environments, consists of a multi-path solid polymer electrochemical sensor, can measure various gases capable of being chemically decomposed, and has the advantages of low power consumption, long service life, good precision and stability and the like. The multi-channel sensor array module can be used for detecting more gases, and the application range is greatly improved. Compared with diffusion air intake, the active air intake unit adopting the form of a fan or an air pump and the like is more stable, and the air flow and the temperature and humidity are more stable through actively feeding air into the air chamber, so that the correction difficulty of the sensor can be effectively reduced.

Furthermore, the invention adopts the benzene, alkane and olefin sensors which are designed independently in a targeted manner, and introduces the oxygen and alcohol sensors for correction, so that the reading of the sensors can be more accurate. Meanwhile, the sensor is designed with low power consumption, so that the personnel maintenance and the energy consumption are greatly reduced.

Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit the same; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.