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Acoustical portable anemometer

 

 

Measurement of gas flow rates in mine workings and industry gas media ducts demands the introduction of modern devices. Underground mining of gassy deposits introduces ventilation problems.

Since all the gases emitted into the mine workings finally find their way into the earth's atmosphere, the environmental aspects of mine ventilation can be considered from two points of view: the necessity of maintaining acceptable atmospheric conditions in mine workings and the need to control gaseous emission into the general atmosphere.

Coal mines are often major sources of methane emission and up to 70% of methane gets into the Earth's atmosphere. The majority of coal deposits of Russia, Ukraine and Kazakhstan are coal seams with methane content varying from several cubic meters per ton in low gassy seams, to 26- 28 cubic meters in seams and rocks of high gas content. The process of methane concentration control in the mine workings requires constant measuring of two parameters: methane concentration and gas flow rate. The present report is devoted to elaboration of velocity and flow rate integrating sensors.

 

  

(wind-gage) APA - 1

Acoustical portable anemometer

Acoustical portable anemometer (wind-gage) APA - 1

Acoustics is the most perspective way for mine ventilation control devices progress. As had been proved in the Moscow State Mining University on the acoustic basis it’s possible to develop different types of acoustic control hardware: portable anemometers for episodically control, stationary devices for permanent monitoring and also means for metrology support of the ventilation measurements. The Plant of Measurement apparatus – partner of MSMU is ready to provide any request.

The main feature - special air-metric channel, supplied with ceramics electro-acoustic transducers. The principle of its operation is based on the dependence of the velocity of the acoustic vibrations arriving at the receiver upon the air-gas velocity. The device does not disturb the aerodynamic structure of the flow, has no moving elements and is very sensitive and precise.

The scheme of the digital signal processing system is intended for integration of momentary rates of flow and for compensation of measurement error. The special advantage of this instrument is the flowmeter channel with its special design within which the air-acoustic interaction takes place. The method of introduction of the acoustic vibrations into the channel and the isolation from any kind of disturbances are embodied in the unique system design.

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