Application of Optical Fiber Pressure Sensor FOP-M in Measuring Air Pressure in Mines

Mine is a general term for shafts, chambers, equipment, ground buildings and structures that form an underground coal mine production system. Sometimes the inclined shafts, vertical shafts, and flat tunnels in the underground development of mines are also called mines. The determination of the size of the mine field, mine production capacity and service life of each mine is one of the key issues that must be resolved in the mine's own design. Mine production capacity generally refers to the designed production capacity of the mine, expressed in ten thousand t/a. The original production capacity of some production mines needs to be changed due to various reasons, so the capacity of each production system of the mine must be re-approved, and the comprehensive production capacity after the approval is called the approved production capacity.

Mines mined underground. Sometimes the inclined shafts, vertical shafts, and flat tunnels in the underground development of mines are also called mines. Mine development has a significant and far-reaching impact on the overall production and construction of metal mines or coal mining pits. It not only affects the amount of infrastructure construction of the mine, the initial investment and the speed of construction, but more importantly, it will determine the production conditions and technology of the mine in the long term. Economic Indicators. Mine development refers to the excavation of a series of shafts and tunnels from the ground surface to the mining area. The main problems that need to be solved in mine development are: correctly divide the minefield, choose a reasonable development method, determine the production capacity of the mine, divide the mining level according to the elevation, select the appropriate ventilation method, carry out the mining area deployment and determine the mining order of the mining area. Mine development is usually divided into flat tunnel development, inclined shaft development and vertical shaft development in the form of shaft. The use of reasonable mining methods is the key to good mine production.
When coal seams are formed, they are generally horizontal or nearly horizontal, and are continuous and complete within a certain range. However, in the subsequent long-term geological history, various movements of the earth's crust occurred, and the spatial morphology of coal seams changed, forming monoclinic structures, fold structures, and fault structures. When we mine coal, we must pay attention to the trend and inclination of the coal seam.
Mine development can be divided into shaft development, inclined shaft development, flat tunnel development and comprehensive development. The main shaft and transport lanes all need permanent support. They can be supported by masonry support, arch support, and roof support. Bolt support, bolt shotcrete support, anchor mesh and shotcrete support, anchor rope support, metal arch support, stone support, reinforced concrete support, and of course the combined support between various supports Protect. Temporary support is needed for the mining face, mainly including dot pillars, hydraulic pillar support, and wooden pillar support. Coal mining generally adopts receding coal mining, and strengthens support while mining. In the goaf area, the filling method or the natural collapse method is generally used to treat the roof.
There is a direct relationship between the atmospheric pressure change of the mine and the depth of the well. This is because the air temperature in the mine is affected by the temperature gradient dt/dz between the temperature of the stratum and the depth of the rock mass (in the absence of an underground heat source), which causes the air density in the direction of the extension of the well. p increases as the depth z increases, that is, dp/dz>0. Due to the influence of the inherent temperature field of the surrounding rock structure, when the depth of the well reaches 200m or more, the test can find that the density of the air in the mine has a large difference in the direction of the depth of the well. , There are several uneven density layers.
In some countries in Europe and America, the fluid with uneven density is called stratified flow, and in Japan it is called density flow. Since the 1950s, my country has adopted the name Density Current. In fact, there are quite a lot of stratification phenomena in fluids; for example: ①Due to the action of gravity, the density of the atmosphere near the ground is greater than that of the high altitude, forming various layers. Deep lakes, reservoirs and oceans have high surface temperature and density due to sunlight. It is small, with low temperature and high density in the deep layer, and obvious stratification often occurs. In this case, the internal density of the fluid changes mainly in the vertical direction, and there is almost no change in the horizontal direction; ②Industrial cooling water is discharged into rivers and lakes When the water temperature is high along the surface and the water temperature in the lower part is low, the temperature difference and heavy flow will occur; ③When the local ventilator for the mine sends the fresh air into the working face through the remote air duct, the fresh air flow and the dirty air flow of the working face are at the outlet of the air duct A two-layer density flow with density difference is formed in the front; ④ The density of gas and air are different. When the flow velocity is lower than a critical value, the gas in the mining area roadway gathers above the roof to form a stratified density flow of gas and air. Based on the phenomenon of fluid density flow, the stratified flow is identified and understood as follows: In the gravity field, the air in the mine with uneven density forms a layered flow, and its density changes mainly in the vertical direction to form a nearly horizontal layer. . The reason for the density difference of air fluid is mainly due to the difference in temperature, which is aimed at the phenomenon of stratified density flow of atmospheric fluid in nature.
Based on the mathematical model of air pressure measurement elevation and the design principle of gas pressure sensor, the application of digital analog circuit, single-chip microcomputer and its related circuit and programming design technology has been developed to measure the air pressure (absolute pressure), relative pressure, and atmospheric density of the mine ventilation system resistance parameters. It is a new digital instrument with common technical parameters of mine ventilation system such as temperature and relative elevation. Compared with the existing barometer, this instrument has increased the measurement of air temperature, density and relative elevation value of the measuring point (absolute height change value of the measuring point).

Finally, I recommend an optical fiber sensor that can be used in mines to measure air pressure. The high-quality optical fiber pressure sensor introduced by Gongminwang from abroad-FOP-M, FOP-M is a kind of optical fiber pressure sensor, mainly used in occasions where high temperatures may occur. , Such as aviation and defense. In addition, this sensor is also a useful tool for general industrial applications in harsh and hazardous environments. FOP-M also has the following advantages: not affected by EI/RFI, small size, reliable measurement in harsh environments, high accuracy, and corrosion resistance. The FOP-M fiber optic pressure sensor is based on the recognized Fabry-Perot (Fabry-Perot) interference principle. The unique design of the sensor is based on the segregation measurement of the silicon film, which is completely different from the traditional pressure measurement technology. The pressure change will cause the length of the Fabry-Perot interference cavity to change. At this time, even if the environment of temperature, EMI, humidity and vibration is extremely harsh, our optical fiber signal conditioner can continuously measure the length of the interference cavity with high precision. This pressure sensor provides better and more reliable pressure measurement for existing applications in the industry. At the same time, the sensor also has the ability to expand for new applications with high operating temperatures. The FOP-M fiber optic pressure sensor has a max temperature resistance of 150°C (302°F), which makes it an ideal product for any scientific research field where high temperature conditions exist.