CN205449790U

CN205449790U - Spectral absorption type methane detector

Info

Publication number: CN205449790U
Application number: CN201620004377.9U
Authority: CN
Inventors: 丛梦龙
Original assignee: Inner Mongolia University for Nationlities
Current assignee: Inner Mongolia University for Nationlities
Priority date: 2016-01-06
Filing date: 2016-01-06
Publication date: 2016-08-10
Anticipated expiration: 2026-01-06

Abstract

The utility model provides a spectral absorption type methane detector, including circuit system, shell and air chamber, circuit system adopts the modularization, connects tail optical fiber diode laser module, fuzzy PID temp. Control module, FC joint tail optical fiber photoelectric detector module, detector biasing module, signal processing module, output display module, button processing module, WIFI module, power module including microcontroller module, laser instrument drive module, FC, the air chamber is the smooth pipe of one section inner wall, and the evenly distributed aperture is opened to the side, and two terminal surfaces are equipped with the internal thread hole, the shell includes display screen, " ON / OFF " key, " sensitivity dynamic " selecting button, power cord interface, draws the round hole of optic fibre, connects WIFI's antenna, WIFI module cooperation router etc. Is realized the network deployment and is measured, raises the efficiency, circuit system is in the shell, and the air chamber is connected the air chamber through optic fibre outside arranging the shell in with circuit system, and reduction dust and vapor make the detection more accurate to circuit component's influence.

Description

A kind of spectral absorption type methane detector

Technical field

This utility model relates to a kind of methane detector, particularly to a kind of spectral absorption type methane detector.

Background technology

Methane gas is the one of greenhouse gases, closely related with global warming greenhouse effect phenomenon, is also simultaneously one of the important composition of methane gas, and gas explosion accident usually threatens mine safety, and methane gas is the most closely bound up with mining safety.Therefore, detection concentration of methane gas is significant.Methane is compared with carbon dioxide, and aerial concentration is far below carbon dioxide, and detection methane gas is proposed the highest requirement to the detection sensitivity of equipment, capacity of resisting disturbance.In existing detection equipment, the operation principle of spectral absorption type methane detector is Bill's Lambert's law, utilizes gas to be measured to have this feature of selective absorbing to light, light decrement is converted into the signal of telecommunication, it is achieved the measurement to gas concentration.Spectral absorption type methane detector, compared with traditional semiconductor-type, catalytic combustion type and thermal conductivity gas detection technology, has highly sensitive, selectivity strong and without advantages such as catalyst poisonings.But the circuit part of existing spectral absorption type methane detector and air chamber are together placed in tool housing, dust can together enter instrument internal with gas to be measured with steam and contact with component, affects testing result.

Utility model content

For solving above-mentioned technical problem, this utility model provides a kind of spectral absorption type methane detector, Circuits System is used to be enclosed in enclosure, air chamber is placed in outside shell, by optical fiber, air chamber is connected with Circuits System, reduce dust and the steam impact on component in gas to be measured, make detection more accurate.

For reaching above-mentioned purpose, the technical solution of the utility model is as follows: a kind of spectral absorption type methane detector, including Circuits System, shell and air chamber, it is characterised in that:

Described Circuits System includes micro controller module, Laser Drive module, FC joint tail optical fiber diode laser module, fuzzy temperature control module, FC joint tail optical fiber photodetector module, detector biasing module, signal processing module, output display module, WIFI module and power module；

Described air chamber is the pipe of one section of inner wall smooth, opening equally distributed aperture in pipe side to circulate for gas to be measured, the center of two end faces of pipe is provided with the internal thread hole mated with described FC joint tail optical fiber diode laser module and FC joint tail optical fiber photodetector module joint；

Described shell include display screen, " ON/OFF " button, " sensitivity/dynamic range " selection key, three phase mains line interface, for drawing two circular holes of optical fiber, and connect the antenna of WIFI module；

Circuits System is closed in enclosure, and air chamber is placed in outside shell, and air chamber is connected with Circuits System by optical fiber.

In described Circuits System, Laser Drive module includes integrated operational amplifier OP07, resistance R1, R2, R3, R4, Rs, electric capacity C1 and audion S8050.

Described detector biasing module includes integrated operational amplifier LMH6629 and the feedback resistance Rf being connected electrically, compensates resistance Rc, compensation electric capacity Cf, compensation electric capacity Cc.

Described signal processing module includes integrated operational amplifier AD797, resistance R5, resistance R6, three terminal potential device R7, electric capacity C2 and electric capacity C3.

Described air chamber uses the stainless pipe of one section of inner wall smooth.

Shell is rectangular structure, uses aluminum alloy material, and corner is fillet, and display screen uses LCD12864 LCDs.

nullDescribed Circuits System uses modular construction，Micro controller module is for regulating and controlling each submodule collaborative work、Laser Drive module is for providing operating current for laser instrument、FC joint tail optical fiber diode laser module is used for launching infrared light、Fuzzy temperature control module is used for monitoring and controlling laser. operating temperature、FC joint tail optical fiber photodetector module is used for receiving optical signal、Detector biasing module is used for converting optical signal into analog voltage signal、Signal processing module is for being filtered the voltage signal of detector biasing module output and amplify、Output display module is used for showing gas concentration information and detector work state information、Keystroke handling module is for being identified operational order、WIFI module for being transferred to coordinator and receiving coordinator instruction by detection data，And power module is used for 220 volts of input ACs electricity through over commutation、The links such as filtering and DC-DC conversion transfer each module work required voltage in system to.

Operation principle: according to lambert's Bill GAS ABSORPTION theorem, when infrared light transmits in gaseous medium, its energy can optionally be absorbed, the intensity of absorption depends on that optical path length, absorbing light spectral line be strong and the product of gas sample concentration.When optical path length and absorbing light spectral line give by force timing, utilize the magnitude of voltage detecting the representative attenuated optical signal amount obtained, it is possible to the anti-concentration value releasing gas to be measured.

In Circuits System, micro controller module exports and changes to the magnitude of voltage of Laser Drive module, laser module output wavelength can be made to finely tune within the specific limits, thus it is corresponding with the GAS ABSORPTION peak of varying strength, during testing requirement high sensitivity, laser module output wavelength is adjusted on stronger GAS ABSORPTION peak, improve sensitivity, when testing requirement dynamic range is wide, laser module output wavelength is adjusted on more weak GAS ABSORPTION peak, reduction sensitivity, to exchange the expansion of detection dynamic range for, is arranged such and can achieve two kinds of detection ranges switchings.WIFI module in Circuits System is responsible for serial data to transfer wireless network signal to, is sent in portable set or the server of control centre by router, so can form sensor network, it is achieved multi-point remote mobile monitoring.

The beneficial effect of the technical program includes:

A kind of spectral absorption type methane detector that 1 the technical program provides, whole Circuits System is closed in the enclosure, and the steam in outside gas to be detected will not contact with electronic devices and components, will not be affected by wet environment during detected gas, can be moistureproof；Air chamber is placed in housing exterior, is connected with optical fiber by FC joint, it is simple to dismantles and cleans, it may have dust-proof effect；

2The technical program has two amounts journey when detected gas concentration, can carry out selecting switching according to the requirement of gas concentration situation and sensitivity；

WIFI module in 3 the technical program Circuits System coordinates router, coordinator to achieve networking measurement, is effectively improved operator's work efficiency；

4 the technical program testing results are more accurate, and service life of equipment is the most longer.

Accompanying drawing explanation

In order to be illustrated more clearly that technical solutions of the utility model, below the accompanying drawing used required described in embodiment and this technology is briefly described.

Accompanying drawing explanation

Fig. 1 is structural representation of the present utility model；

Fig. 2 is Circuits System block diagram；

Fig. 3 is the circuit theory diagrams of Laser Drive module；

Fig. 4 is the circuit theory diagrams of detector biasing module；

Fig. 5 is the circuit theory diagrams of signal processing module；

Fig. 6 is the structured flowchart of fuzzy temperature control module；

Fig. 7 is main program flow chart；

Fig. 8 is the fundamental diagram of WIFI module；

Fig. 9 is that embodiment is measured in multiple spot detection networking of the present utility model.

In Fig. 1: 1 Circuits System, 2. air chamber, 3. laser instrument tail optical fiber, 4. detector tail optical fiber, 5. shell, 6.LCD12864 display screen, 7. " ON/OFF " button, 8. " sensitivity/dynamic range " selection key, 9. antenna, 10. three phase mains line interface.

Detailed description of the invention

Below in conjunction with the accompanying drawings and embodiment the utility model is described in further detail:

A kind of spectral absorption type methane detector, including Circuits System, shell and air chamber: described Circuits System includes micro controller module, Laser Drive module, FC joint tail optical fiber diode laser module, fuzzy temperature control module, FC joint tail optical fiber photodetector module, detector biasing module, signal processing module, output display module, WIFI module and power module；

Described air chamber is the stainless pipe of one section of inner wall smooth, opening equally distributed 6 apertures to circulate for gas to be measured in pipe side, the center of two end faces of pipe is provided with the internal thread hole mated with described FC joint tail optical fiber diode laser module and FC joint tail optical fiber photodetector module joint；

Described shell shell is rectangular structure, use aluminum alloy material, corner is fillet, including LCD12864 LCDs, " ON/OFF " button, " sensitivity/dynamic range " selection key, three phase mains line interface, it is used for drawing two circular holes of optical fiber, and connects the antenna of WIFI module；

In Fig. 1, LCD12864 display screen (6), " ON/OFF " button (7) and " sensitivity/dynamic range " selection key (8) embed in detector shell (5), three phase mains line interface (10) is positioned at the lower left (front view) of detector shell (5), the laser that FC joint tail optical fiber diode laser module in detector shell (5) inner circuit system (1) sends is coupled to the arrival end of air chamber (2) by optical fiber (3), after air chamber (2) is propagated, it is coupled in Circuits System (1) on the photosurface of FC joint tail optical fiber photodetector module by the optical fiber (4) of air chamber (2) port of export, antenna (9) electrically connects with the WIFI module in Circuits System (1).

Circuits System shown in Fig. 2 includes FC joint tail optical fiber diode laser module, Laser Drive module, fuzzy temperature control modules, signal processing module, detector biasing module, FC joint tail optical fiber photodetector module, WIFI module, output display module, keystroke handling module, micro controller module and power module.

Described micro controller module is with STM32F103VET6 chip as core.STM32F103VET6 is the CortexTM-M3 kernel microcontroller based on ARM of ST company research and development, and running voltage is 2.0～3.6V, and operating frequency is up to 72MHz, has abundant enhancement mode I/O port and is connected to the peripheral hardware of two APB buses.Chip comprises the ADC of two 12, the DAC of two 12,3 general 16 bit timing devices and 1 PWM intervalometer, also comprises standard and advanced communication interface；2 I2C interfaces, 3 USART interfaces, a USB interface and a CAN interface etc., peripheral circuit is simple.In micro controller module, the PA4 pin (programmed configurations is DAC output) of STM32F103VET6 chip electrically connects with the VIN input of Laser Drive module.

Fig. 3 is the circuit theory diagrams of Laser Drive module.Described Laser Drive module includes integrated operational amplifier OP07, resistance R1, R2, R3, R4, Rs, electric capacity C1 and audion S8050；The VIN port of described Laser Drive module is electrically connected by R3 with OP07 inverting input, + 5V the outfan of power module electrically connects with the colelctor electrode of S8050, the emitter stage of S8050 and one end of Rs, one end of R2 electrically connects simultaneously, the other end of Rs electrically connects with one end of positive pole LD+ and R4 of FC joint tail optical fiber diode laser module simultaneously, the other end of R2, one end of C1, one end of R1 electrically connects with the in-phase input end of OP07 simultaneously, the other end ground connection of R1, the other end of C1 and the outfan of OP07, the base stage of S8050 is electrically connected simultaneously, the other end of R4 electrically connects with OP07 inverting input, the negative pole LD-ground connection of FC joint tail optical fiber diode laser module.According to the empty short concept disconnected with void of operational amplifier, the electric current flowing through laser instrument is linear with input voltage VIN, and the wavelength of launching of diode laser changes, it is achieved that utilize the function of STM32F103VET6 chip controls laser emission wavelength with the change driving electric current.

Fig. 4 is the schematic diagram of detector biasing module.Described detector biasing module includes integrated operational amplifier LMH6629 and the feedback resistance Rf being connected electrically, compensates resistance Rc, compensation electric capacity Cf, compensation electric capacity Cc；The inverting input of described integrated operational amplifier LMH6629 electrically connects with one end of negative pole PD-, Rf, one end of Cf of FC joint tail optical fiber photodetector module simultaneously, the positive pole PD+ ground connection of FC joint tail optical fiber photodetector module, the other end of Rf and Cf electrically connects with the outfan of LMH6629, the in-phase input end of LMH6629 electrically connects with one end of one end of Rc, Cc simultaneously, the other end ground connection of Rc and Cc.When there being light to irradiate photodetector, generation being proportional to the electric current of light intensity, direction is that the negative pole from photodetector flows to positive pole, and feedback resistance Rf, to this current sampling, completes the transformation process of light intensity photogenerated current output voltage eo.Resistance Rc can offset operational amplifier inverting input and photogenerated current is shunted the impact caused, and electric capacity Cf is for eliminating the self-oscillation phenomenon of circuit, and electric capacity Cc is for weakening the noise that resistance Rc introduces.

Fig. 5 is the circuit theory diagrams of signal processing module.Described signal processing module includes integrated operational amplifier AD797, resistance R5, resistance R6, three terminal potential device R7, electric capacity C2 and electric capacity C3；Input e0 with R5 of described signal processing module, the in-phase input end order of R6 and AD797 electrically connect, one end of C2 electrically connects with R5, R6 simultaneously, the other end of C2 electrically connects with R7 fixing end, an outfan e01 of AD797, another fixing end of R7 and one end ground connection simultaneously of C3, the other end of C3 electrically connects with the in-phase input end of AD797, and the sliding end of R7 electrically connects with the inverting input of AD797.The essence of this circuit is the step low-pass active filter of a Sallen-Key structure, its input e0 receives the voltage signal from the output of previous stage detector biasing module, outfan e01 electrically connects with the PF6 pin of micro controller module STM32F103VET6 chip, and PF6 is set as ADC function by programming.Resistance R5, R6, the value of electric capacity C2, C3 determines the cut-off frequency of low pass filter, and the sliding end regulating three terminal potential device R7 can change the quality factor of this low pass filter.

Fig. 6 is the structured flowchart of fuzzy temperature control module.FC joint tail optical fiber diode laser module enclosed inside critesistor, laser diode and thermoelectric refrigerator, owing to three is close to, therefore the temperature of critesistor is approximately equal to the temperature of laser diode.nullAfter this temperature is converted to voltage by current sample，Send into the PF7 pin (programming is set as ADC function) of STM32F103VET6 chip，Complete the conversion representing between the magnitude of voltage of temperature and digital quantity，Next this digital quantity is compared with the preset temperature digital quantity being stored in STM32F103VET6 chip，The rate of change of calculated error e and e is sent in fuzzy inferior (programming realization)，The proportional KP in PID controller is updated with this、Integral term KI and differential term KD，The digital quantity of PID controller output is converted into analog voltage，Export from the PA5 pin (programming is set as DAC function) of micro controller module STM32F103VET6 chip，PA5 pin electrically connects with the CTL1 pin of thermoelectric refrigerator driving chip MAX1968，MAX1968 produces corresponding Bipolar current according to this voltage，To thermoelectric refrigerator heating or refrigeration，And then achieve the temperature control of laser diode.

Fig. 7 is main program flow chart.nullAfter detector start，Micro controller module is firstly the need of gathering thermistor temp，Judge whether diode laser works under room temperature condition (296K)，"Yes" then enters LCD display subroutine 1，"No" then enters fuzzy temperature control subprogram to adjust temperature，In LCD display subroutine 1，Liquid crystal display screen shows that " sensitivity/dynamic range " points out operator to select，When " sensitivity/dynamic range " selection key (8) in Fig. 1 are not pressed，Acquiescence enters LCD display subroutine 2，Screen shows " sensitivity is preferential "，Micro controller module calls D/A varitron program 1,The absworption peak making the magnitude of voltage of output stronger with gas absorption spectra is corresponding，When " sensitivity/dynamic range " selection key (8) are pressed，Enter LCD display subroutine 3，Screen shows " dynamic range is preferential "，Micro controller module calls D/A varitron program 2，The absworption peak making the magnitude of voltage of output more weak with gas absorption spectra is corresponding，Hereafter microcontroller enters collection and the processing links of concentration signal，First analog voltage sampling subprogram is started，Judge whether after sampling to outrange，If outranging, illustrate that gas concentration is too high，D/A varitron program 2 before returning to，Low light level spectrum absworption peak is utilized to detect，If not outranging, enter digital quantity concentration conversion subprogram，It is scaled gas concentration value after the digital quantity collected is carried out digital filtering and regression analysis，Call serial communication subprogram and this concentration value is sent to coordinator，Finally call LCD display subroutine 4 concentration information is shown.

Fig. 8 is WIFI module fundamental diagram.This WIFI module is to use the flush bonding module of USB (universal serial bus), and indices meets network standard, built-in ICP/IP protocol stack, it is possible to realize the conversion between user's serial ports, Ethernet, 3 interfaces of wireless network (WIFT).The Serial output mouth UART_TXD of WIFI module connects the PB11 pin of STM32F103VET6 chip in micro controller module, the serial input mouth UART_RXD of WIFI connects the PB10 pin of STM32F103VET6 chip, PB11 and PB10 pin is respectively set as serial input mouth and the Serial output mouth of STM32F103VET6 chip by programming.

Fig. 9 is that embodiment is measured in multiple spot detection networking of the present utility model.As it can be seen, built a small wireless sensor network based on tree in embodiments, network includes 3 terminals, a router and a coordinator.Terminal unit is i.e. positioned over monitoring point 1, the spectral absorption type methane detector that the air chamber of monitoring point 2 and monitoring point 3 is external, the gas to be measured of each monitoring point is diffused in air chamber by the aperture of air chamber, the laser that the FC joint tail optical fiber diode laser module of detector enclosure sends is coupled to one end of air chamber by optical fiber, after air chamber is propagated, it is coupled on the photosurface of FC joint tail optical fiber photodetector module by the optical fiber of the other end, the current signal of output is sampled as magnitude of voltage after detector biasing module, after this magnitude of voltage is filtered and amplifies by signal processing module, it is digitized processing and the regression analysis of voltage concentration by its input micro controller module, the result obtained is shown by the LCD12864 liquid crystal display screen being embedded on detector shell.Air chamber uses FC joint to be connected, detachably with optical fiber, it is simple to cleaning dedusting, air chamber shell is drawn and uses fluid sealant to close between the circular hole of optical fiber and optical fiber, it is ensured that steam, dust etc. will not enter enclosure and impact Circuits System.Serial data is converted to wireless network signal, coordinator and terminal and realizes including control instruction input and the data interaction of concentration information output by wireless router by the WIFI module of Circuits System.This coordinator can be portable set, it can also be server, operator can be in the case of not entering monitoring field, obtain the gas concentration data of each monitoring point easily, when data volume is little, operator only needs phone network can realize the operation of equipment and obtain total data, conveniently, safely and efficiently.

A kind of spectral absorption type methane detector that the technical program provides, uses Circuits System in the enclosure, and air chamber is placed in outside shell, is connected with optical fiber by FC joint, has good protection against the tide, dust-proof effect, and testing result is more accurate；When detected gas concentration, there is two amounts journey, can carry out selecting switching according to testing requirement；The technical program achieves networking and measures, and is effectively improved operator's work efficiency.

Described above to the disclosed embodiments, makes professional and technical personnel in the field be capable of or uses this utility model.Multiple amendment to these embodiments will be apparent from for those skilled in the art, and generic principles defined herein can realize in the case of without departing from spirit or scope of the present utility model in other embodiments.Therefore, this utility model is not intended to be limited to the embodiments shown herein, and is to fit to the widest scope consistent with principles disclosed herein and features of novelty.

Claims

1. a spectral absorption type methane detector, including Circuits System, shell and air chamber, it is characterised in that:

A kind of spectral absorption type methane detector the most according to claim 1, it is characterised in that: in described Circuits System, Laser Drive module includes integrated operational amplifier OP07, resistance R1, R2, R3, R4, Rs, electric capacity C1 and audion S8050.

A kind of spectral absorption type methane detector the most according to claim 2, it is characterised in that: described detector biasing module includes integrated operational amplifier LMH6629 and the feedback resistance Rf being connected electrically, compensates resistance Rc, compensation electric capacity Cf, compensation electric capacity Cc.

A kind of spectral absorption type methane detector the most according to claim 3, it is characterised in that: described signal processing module includes integrated operational amplifier AD797, resistance R5, resistance R6, three terminal potential device R7, electric capacity C2 and electric capacity C3.

5. according to a kind of spectral absorption type methane detector described in claim 1 or 4, it is characterised in that: described air chamber uses the stainless pipe of one section of inner wall smooth.

A kind of spectral absorption type methane detector the most according to claim 5, it is characterised in that: described shell is rectangular structure, uses aluminum alloy material, and corner is fillet, and display screen uses LCD12864 LCDs.