Abstract
Content
- Introduction
- 1. Actuality of theme
- 2. The purpose and objectives of the research, the expected results
- 3. Overview of Research and Development
- References
Introduction
Each year, rising production volumes of the coal industry, which in turn causes an increase in gas and dust emissions in the mine air shafts, important for the safety of underground work is to control the concentration of fine dust, system performance and reliability of the results, because heavy dust emissions lead to increased likelihood of an explosive situation [7,8], and contrary to NPAOT "Safety in Coal Mines" [1,9].
1. Theme urgency
Today, there are many devices that can perform similar tasks, but most of them do not reflect the dynamics characteristics of the object of the study. The presence of various factors that affect the results of measurements (temperature, humidity, etc.) makes it difficult to create dust meters with the required accuracy and performance indicators. Thus, we see that this topic is very relevant and requires further development.
2. The purpose and objectives of the research, the expected results
One of the main goals of this paper is to select and justify the method of measuring the concentration of dust in coal mines, which will create a mathematical model for measuring the concentration of dust, which will take into account the effect of destabilizing factors (temperature, humidity, etc.).
The ultimate goal of this work is to validate the structure of the electronic control system parameters dusty mixture mine air shafts.
To achieve the objectives set and solved the following problems:
- analyze the existing methods of monitoring the concentration of dust in coal mines in terms of system performance and the accuracy of the measurement results.
- Justify the choice of method.
- Consider the effect of destabilizing factors
3. Overview of Research and Development
The following are the most common methods to control airborne dust (dust concentration) in the mine atmosphere:
- Gravimetric (weight) method based on a set of samples of dust, determining its mass and recording measurements on site or remotely, characterized by relatively large dimensions of the apparatus and low operational reliability. Use this method when creating dust concentration meter for mining conditions, without human intervention, it is not possible.
- Electrical methods (electroinduction, electrical contact, etc) based on the measurement of the charge flow or dust particles on the measurement of the number of charged particles. Primary electrical signal is generally proportional to the total surface of the dust particles and is a measure of their mass. Therefore a change in the composition of particulate dust can cause measurement errors. To a large extent the result of the measurement affects the material composition and electrical properties of the dust, loses efficiency at a relative humidity of 80%. The devices constructed by this method are bulky and consume a lot of electricity.
Ratiometric method is based on determining the fraction of beta radiation absorbed drug dust separated in the substrate. The measurement result this method practically does not depend on the composition of the dust and is determined only by its mass. Sensors pyleizmeritelnyh devices based on radiometric methods are relatively complex. They have moving parts, complex electrical circuits of amplifiers and converters primary signal. Such devices are expensive. The use of sensors in the considered particulate air pollution monitoring equipment can be justified only good metrological characteristics.
Optical methods based on the determination of the proportion of light absorbed or scattered by the dust cloud or mixture of dust separated in the substrate. The measurement result of these methods is expressed in units of concentration of gravity depends on the fineness of the dust because of its optical properties are determined primarily a surface area of. Furthermore, the measurement result affects the dust density and its reflectivity. When measuring the concentration of dust near sources of release in underground coal mines fluctuations disperse composition of dust can produce measurement error of the total mass of dust ± 34%, and the fine dust ± 11%, in the same conditions, a possible change of the material composition of dust causes the error of ± 9, 5%.
By optical methods also include turbidimetric method [10] which is used for the analysis of suspensions, emulsions, suspensions, and various other turbid media.
The intensity of the beam of light passing through such a medium is reduced due to scattering and absorption of light by suspended particles.
Turbidimetric methods are based on the observation of the weakening of the past through the medium under investigation probing radiation, the characteristics of which is estimated dispersion and concentration of aerosol. Unlike optical methods, turbidimetric method uses a radiation source 2 (one in the visible spectrum, or other items in the infrared or other wavelength).
The main advantage of turbidimetric methods is their high sensitivity.
References
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