Hazardous Gas Detecting Method Applied in Coal Mine Detection Robot---IEEE2011

7/31/2019 Hazardous Gas Detecting Method Applied in Coal Mine Detection Robot---IEEE2011

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Hazardous Gas Detecting Method Applied in Coal Mine Detection Robot

Niu Zhigang, Wang Lu

College of Mechanical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, [email protected]

Abstract As one of the largest coal production and

consumption countries in the world, China is also one of the

related accidents occurred frequently countries such as gas

explosion, flood, breaking out of fire during the exploitation of

coal mine. Coal Mine Detection Robot can be substituted or

partial substituted for emergency workers to enter the mine

shaft disaster site and detect hazardous gas and do some

environmental exploration and surveying task. Coal Mine

Detection Robot uses infra-red spectrum absorption way to

detect methane, carbon monoxide and such gas

simultaneously. The principle of gas surveymeter of infra-red

spectrum is according to the selectively absorption of infraredradiation by the mash gas, CO to achieve the detection of their

concentration. The advantages of this kind of hazardous gas

detecting are: simultaneously and rapidly detecting methane,

CO and high sensitivity, good selectivity and fast response.

Otherwise, it is easy to be taken by robot due to its simple and

light structure, have a lager detection range and probe is not

easy failure to be poisoning and aging.

Keywords- Coal Mine Detection Robot; Methane; CO; Infra-

red Spectrum Absorption

I. INTRODUCTION

China is one of the largest coal production and

consumption countries in the world, among its energyindustry, coal accounting for about 70% in production andconsumption structure of primary energy sources, and by2050 its expect to accounting for more than 50%. For thepoor geological conditions of the coal bed of China , thereare so many highly gassy mine that accident occurredfrequently such as fire damp explosion, water burst, breakingout of fire during the exploitation of coal mine. Therefore,how to accurately detect and prospect the incipient accidentbefore it happens and how to rescue in maximum possibilityafter it happens is the most important thing. At recent times,there is little research about Coal Mine Detection Robot,only a little research on rescue robots for surface buildings'collapse and fire-fighting robot, and these robots are not

suitable for detecting coal mine accident

[1]

. The research ofCoal Mine Detection Robot (figure 1) can make the coalmine rescue works improving a lot, and reduce the casualtiescaused by mine accident. It will be substituted or partialsubstituted for emergency workers to enter the worksite andto carry out environmental prospecting and surveying task.As the requirement of limited size and load for the robot inspecial circumstances, and many items to detect, the researchof detecting by coal mine underground explorative robothave great practical significance and advanced natures.

Figure 1. Coal Mine Detection Robot

II. CHARACTERISTICS OF THE DETECTED GAS

Coal Mine Detection Robot mainly detects mash gas andcarbon monoxide. The mash gas is the generic terms of themixed gas which mainly make up of methane (CH4) in theunderground of the coal mine shaft, and sometimes it

abbreviate to methane. It is a kind of gas that formed duringthe process of coal-forming and stored in a large numberamong the coal bed, and the most damaging gas in theunderground of the coal mine shaft. The mash gas is a kindof colorless, odorless, tasteless, non-toxicity gas, and itsdensity is 0.7167kg/m, when the content of methane in air isaccounting for 5%~16%. It possesses the risk of explosion;when the content account for 9.5%, the explosive power islargest; when the concentration of methane in air isexorbitance, the harm to human body is it can killed peoplecaused by suffocation when it is over the limitation, thoughthe methane itself is nontoxic. CO is a kind of colourless,odourlessness, tasteless, nonirritant gas, and its proportion is0.967kg/m, almost insoluble in water. It could explode

When it mixed with air and its accounting for 12.5~80%

[2]

.In the underground of coal mine haft, when theenvironmental temperature reaches certain condition, thecoal will be spontaneous combustion, as the Oxygen supplyof those places is insufficient, it will cause combustioninadequate and forms a large amount of CO. CO have astrong attractive to hemoglobin. When CO enteredrespiratory system it will cause anoxemia, and lead tohistanoxia, and the inhibition of tissue respiration can killedpeople caused by suffocation. According to their features ofthe mash gas and CO they are both possess explosive, and

2011 Third International Conference on Measuring Technology and Mechatronics Automation

978-0-7695-4296-6/11 $26.00 2011 IEEE

DOI 10.1109/ICMTMA.2011.364

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is considered as the detecting signal, and ray radiation of3

is considered as the reference signal.

Figure 3. Block diagram of three-wavelength single light path

As shows in figure 3, the light emitted from light sourceentered detection chamber, and reach beam splitter throughthe air chamber, the beam splitter divided the luminous beaminto three beams. Each of them get through interferenceabsorbent which with the center frequency of1, 2 and 3 toirradiate on the photoelectric detector, in where converted toelectrical signal. According to formula (1), consideringinterference factor of light path, since the incident ray of thethree kind wavelength passed the gas that to be detected, theoutput electrical signal that get through the detector are:

1 1[ ( ) ( )]

1 0 1 1( ) ( ) ( )

C Li I K D e

+=(3)

2 2[ ( ) ( )]

2 0 2 2( ) ( ) ( )CL

i I K D e +=

(4)

3 3[ ( ) ( )]

3 0 3 3( ) ( ) ( )CL

i I K D e +=

(5)

Among the formula, K(1), K(2), K(3) is couplingparameter of optical system; D(1), D(2), D(3) is the

percent response of electrooptical device; (1)(2)(3)

is the interference factor of the wave path. [5].From the formula (3), formula (4) and formula (5) the

concentration of the being detected gas can be expressed as

0 1 1 14

1 3 0 3 3 3

( ) ( ) ( )1l n

[ ( ) ( ) ] ( ) ( ) ( )C H

I K DC

L I K D

= +

31 3

1

( )ln [ ( ) ( ) ]

( )

i

i

+

(6)

0 2 2 2

2 3 0 3 3 3

( ) ( ) ( )1l n

[ ( ) ( ) ] ( ) ( ) ( )C O

I K DC

L I K D

= +

32 3

2

( )ln [ ( ) ( ) ]

( )

i

i

+

(7)

Because the differences between (1), (2), (3) isquite small, and the ray radiation almost enter and pass thebeing detected gas at the same time, therefore, there isapproximate to:

1 2( ) ( ) (8)

2 3( ) ( ) (9)Appropriate adjustment of optical system makes

0 1 1 1 0 2 2 2( ) ( ) ( ) ( ) ( ) ( )I K D I K D =

(10)

0 2 2 2 0 3 3 3( ) ( ) ( ) ( ) ( ) ( )I K D I K D = (11)

Then formula (3-6) can simplified as3

4

1 3 1

( )1ln

[ ( ) ( )] ( )C H

iC

L i

=

(12)

3

2 3 2

( )1ln

[ ( ) ( )] ( )C O

iC

L i

=

(13)During practical application, the light with wavelength 1,

2 correspond to the absorption line of gas that beingdetected , light of wavelength 3 can not be absorbed bydetected gas( reference wavelength), during the process of

testing it is null value, have 1

3

( )1

( )

i

i

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Hazardous Gas Detecting Method Applied in Coal Mine Detection Robot---IEEE2011