At present, most mines use this type of equipment to pump gas, because the mine gas is a flammable and explosive gas. The selection of a suitable water ring vacuum compressor is critical to the safety of mine gas drainage. In recent years, coal mine safety accidents have emerged in an endless stream, and safety issues have become increasingly important. Some of the safety accidents in various mines are caused by the fact that the pumping equipment does not match the actual environment of the mine, resulting in insufficient gas pumping capacity of the gas pump, resulting in the accumulation of residual gas in the mine.
At present, the selection of vacuum compressors for gas drainage is generally determined directly by the coal mine design institute, and the equipment is provided by the manufacturer. The selection of design institutes is generally selected according to the gas pump selection formula in Mine Gas Drainage Theory and Technology. If the pipeline layout is long, the resistance is large, and the system negative pressure requirement is high, according to this formula The accuracy of selection is not very high.
As a result, the selected equipment does not coincide with the actual environment of the coal mine, and the gas volume of the gas required by the mine is not reached, which poses a safety hazard. Based on the years of application experience of vacuum compressor products in the coal mining industry and the cooperation process with the design institute for many years, we proposed a new method for the selection and application of water ring vacuum compressors in coal mine gas drainage, so that it can run accurately and effectively. To ensure the safety of gas in the process of pumping.
The following is a description of specific selection examples. 9 cases: a mine requires a gas mixing flow of 130Nm3/min, a gas concentration of 30%, and a negative pressure requirement of the drilling port to reach 150Pa. The gas drainage system piping arrangement and the gas demand of each pipeline are shown in the mine gas drainage diagram. The gas is pumped to the gas tank and sent to the residential area for utilization. The user's positive pressure at the gas outlet is required to be 500OPa, and the corresponding water ring vacuum compressor is required.
Determination of parameters In coal mine gas drainage, as long as the main parameters affecting the water ring vacuum compressor are determined: vacuum degree (absorption absolute pressure), discharge pressure, pumping capacity, etc., Model and specifications of the compressor. System negative pressure, discharge pressure and total system resistance The system negative pressure (ie vacuum) includes the borehole negative pressure and the resistance loss of the population pipeline to be overcome by the pumping equipment. The pipeline loss includes frictional resistance and local resistance; the discharge pressure includes gas. The pressure required by the tank and the resistance loss of the discharge pipeline; the total resistance of the system is the sum of the above two, and the mutual relationship formula is: H = (H hole + H person + H out) K (l) H minus two (H drill Hole + H person) K (2) H. = H out x K (3) H person = H Mo + H Bureau (4) In the above formula: H a system total resistance; H negative system negative pressure, that is, water ring vacuum Compressor vacuum; H positive system positive pressure, ie vacuum compressor discharge pressure; H drill, a bore negative pressure; H into a suction pipe maximum resistance loss including discharge line resistance loss and gas tank requirements The pressure reached; H. The maximum frictional resistance loss of the suction line; the local resistance loss of the H-inhalation pipeline is calculated according to 20% of the maximum frictional resistance loss of the suction pipeline; K is an alternate factor.
The gas drainage flow system requires a gas drainage flow rate of 130Nm3/min. Considering the reserve factor K=1.2, the required water circulation vacuum compressor pumping capacity is 6Nm3/min, because the above is also calculated. For the 56216Pa, the pumping amount under the corresponding vacuum state is converted, and then the exhaust pressure is corrected by the exhaust pressure to determine the pumping capacity of the water ring vacuum compressor.
The calculation process is as follows: flow conversion formula: human gas flow, NmVmin; P atmospheric pressure, taking a standard atmospheric pressure l0130Pa calculation. Since the outlet pressure of the water ring vacuum pump is 7136Pa, the discharge pressure does not have much influence on the negative pressure of the system, but has an influence on the pumping capacity of the water ring vacuum compressor and the operating shaft power. Therefore, the empirical formula of the gas volume correction is obtained: S repair = 354m3 /min type: Pl is the absolute pressure of the water ring vacuum compressor discharge port, Pa.
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