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Pleskachev VyacheslavDepartment
of Computer Information Technology and Automation Department of electronic technics Speciality: Electronic systems Theme
of master's work: "Development
and research of the model sample the
electronic system of concentration control of
methane in collieries |
AbstractTheme urgency
With
growth of
depth of development of coal increases foulness framings,
the temperature of layers and
humidity of breeds, increases frequency and intensity gasdynamic
displays that
is interfaced to danger increase at guiding of mountain operations. In
these conditions special value is acquired by questions
of support of the carbon enterprises high-speed and well-tried remedies
of
automatic control of concentration of methane in miner atmosphere.
Existing gages do not provide obtaining of the
information on processes of change of concentration of methane with
small
enough static and dynamic errors. Thus, it is necessary to develop a
model
sample of electronic system for the further learning and development of
ways of
increase of high-speed performance at required accuracy of control of
concentration of methane with compensating of influence of the main
destabilizing factors of miner atmosphere of collieries, as defines a urgency
of the theme master's work. Purpose of the work On the basis of application optical absorption method of concentration control of methane and a mathematical model to develop and research the model sample of the electronic monitoring system of concentration of methane who allows to estimate expediency of development of the given system. Tasks
of the work
–
The analysis of existing
methods and monitoring aids of concentration of methane in miner
atmosphere, from the point of view of
increase of high-speed performance of a measuring instrument at
required
accuracy of
control; – Development
of a
mathematical model of a measuring instrument, on a basis optical
absorption
method
of concentration control of methane
in collieries taking into account
influence of destabilizing factors of miner atmosphere; – Development
of a method of
compensating of influence of a carbon dust and destabilizing factors of
miner
atmosphere on result of measurement of concentration of methane; – Development
of the model
sample of system of measurement of concentration of methane for the
purpose of
carrying out of full-scale tests for determination of metrological
characteristics and an
efficiency estimation; –
Development of programs and
techniques of tests for the model sample, and also the recommendation for use. Prospective
scientific novelty
1. To
have the further development
optical
absorption method of
concentration control of methane
in collieries, on the basis of use of the
open optical measuring channel with
compensating of
influence of
a carbon dust that allows to raise high-speed
performance of a measuring instrument of
concentration of
methane at required accuracy of control. 2.
Development of a mathematical
model of system of measurement on a basis optical
absorption method of concentration control which
considers influence
of destabilizing factors of miner
atmosphere (temperature and pressure change, concentration of a carbon
dust and
accompanying gases) on parameters of an
optoelectronic measuring
instrument. 3.
Development of the model sample
of electronic system control of concentration of methane for an
estimation of
metrological characteristics of
measuring system for real service
conditions. The main material of the workIn the first section the analysis of methods and monitoring aids of concentration of methane in miner atmosphere [1] is made. Being based on results of the fulfilled analysis and requirements to stationary measuring instruments of concentration of methane in collieries, in operation it is offered to use optical absorption method of concentration control of methane with the quasiopen optical measuring channel that provides necessary compensating from influence of destabilizing factors of miner atmosphere. The analysis of influence of destabilizing factors of miner atmosphere (change of temperature, pressure, presence of accompanying gases and water steams, concentration of a carbon dust) on metrological characteristics of the model sample is made. It is installed that by operation of a measuring instrument of concentration of methane in the conditions of a dust content of miner atmosphere of collieries, the error of measurement of concentration of methane increases that in turn does not provide with necessary high-speed performance measurement system agrees state standart requirements. As the decision of the given problem, in operation it is offered to use «a method of compensating of a dynamic error of an infrared measuring instrument of concentration of methane for collieries» [2]. In the second section the mathematical model of measuring system on a basis optical absorption method of control concentration of methane which considers influence of destabilizing factors of miner atmosphere (temperature and pressure change, concentration of a carbon dust and accompanying gases) on parameters of an optoelectronic measuring instrument that allows to estimate metrological characteristics of measuring system for real service conditions is developed. Absorption of optical radiation is described by the law of Bugera-lambert-bera which I intensity of absorption connects to length of a way l and concentration of a researched gas component of Sob of % expression (1), [3].
For a choice of parameters of the open optical channel in operation the transmission ratio of the optical channel the K oc equal to the relation of intensity of past Ioutput ОC to falling Iinput ОC of optical flows is defined:  Where K (lT, P) – coefficient of section of a spectrum of absorption of optical radiation by the methane, depending on temperature T, °K, pressure P, kPа miner atmosphere and concentration of accompanying gases (a row of heavy hydrocarbons). Apparently from expression (2) transmission ratio of the optical channel is non-linear function which contains following variables: (Т, Р,) characterize a state of miner atmosphere l, a micron – length of a wave of spectral lines of absorption of methane, l, m – length of measuring basis of the optical channel (design data). In the optoelectronic unit it is necessary to provide the maximum transmission ratio the Koc of the open optical channel. For determination the Koc following researches are fulfilled: –
An estimation of
characteristics of a spectrum of absorption of methane and a choice of
length
of a wave and
width of spectra of radiators and receivers; – Design
data choice l
–
lengths of measuring basis; – An estimation influence of factors of miner atmosphere – change of temperature and pressure upon results of measurement of volume concentration of methane in a range from 0 to 4об the %, defined by requirements of state standart for collieries. In the third section the block diagram of a measuring instrument of concentration of methane is developed for conditions of collieries (fig. 1). Operation of an optical measuring instrument is fulfilled under control of the unit 11 and consists in the following. Flows of radiation from sources of radiation 1 and 2 simultaneously arrive in measuring optical ditches with quasiopen filters 3 and 4 which passes through two measuring basins to 3 - 5 % of a dust from the general concentration of a dust in miner atmosphere of a colliery. And simultaneously turnes on two sources of radiation 1 and 2 which are installed on one side of measuring basins, and on two detectors of optical measurement 5 and 6 which are allocated on one axis with sources 1 and 2 on other side of measuring basins, optical signals arrive.
Picture 1 – the block diagram of a measuring instrument of concentration of methane for conditions of collieries (animation: size - 110 КБ; image size - 653x210; shots quantity - 5; delay between shots - 100 ms; de number of repetition cycles - 5) Analog signals from detectors with amplifiers 5 and 6 arrive on function generators 7 and 8. These units provide equality of output signals of measuring optical basins at the concentration of methane equal to zero, and also scaling of an output signal which consists in the following is carried out: the maximum output signal corresponds to the maximum value of a range of measurement of concentration of methane (4,0), and a zero – minimum to concentration (0,0) Analog electrical signals from two function generators 7 and 8 sequentially are switched with analog-digital converter 10 by means of the switchboard of analog signals 9. The choice of the measuring channel, an interval and duration of inquiry is defined by a control unit 11. Analog-digital converter 10 under control of the unit 11 transforms with sharing in time electrical signals to the numeral code, for implementation of compensating of a dynamic error of the device by means of a program method of numeral handling of results of measurement. Analog-digital converter 10 interfaced to the computing unit 12 in which storage of the discrete values of output pressure either their relation, or a difference of output pressure [4] in one time interval is carried out. Further in the following time interval through a sampling interval analog-digital converter 10 procedure of measurement repeats and then calculation of concentration of analysable gas for the developed algorithm which repeats calculation in all interval of an operating time of the measuring device is carried out. Under
control of
the unit 11 data about
concentration of
methane in miner
atmosphere of a
colliery are
deduced on the unit of
indication and
registration 13 and by means
of
inter-chip
digital
link 14 means are
transferred in system
of aerogas protection of collieries.
Conclusions Existing methods and tools for measuring the concentration of methane does not provide the necessary speed of the device measuring the concentration of methane in the atmosphere of coal mines. Using optical-absorption method, as well as modern optics and microelectronics will create a high-speed instrument for measuring methane concentration with improved metrological and operational characteristics. At the time
of writing the abstract the master's work is in progress.
Completion and defense planned in November 2011. The literature list:
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