(Guangdong Foshan Water Pump Factory Co., Ltd., Foshan, Guangdong 528000) Based on the years of application and practical experience of Foshan Shuiying Factory Co., Ltd., this article discusses the application of water ring vacuum pump compressor in coal mine gas drainage.
1 Overview Water ring vacuum compressor is a kind of equipment that uses water as working fluid to suck solid particles and water-insoluble gas. Compared with other vacuum pumps, it has the following characteristics: The pump has no friction and reliable performance. , Long life, easy maintenance.
The water in the pump is used as the seal and the liquid ring. The temperature change during gas compression is very small. It belongs to isothermal compression, and is especially suitable for pumping poisonous, harmful, flammable and explosive gases.
The water ring vacuum compressor is a device that integrates negative pressure suction and positive pressure discharge. It can be used as a vacuum pump and compressor at the same time.
Based on the above advantages, the application of water ring vacuum compressors in gas drainage of coal mines has become more and more widespread. On the one hand, the gas in the mine can be extracted, and on the other hand, the gas can be sent to the designated place with certain pressure. For residents, it is different from the way that a commonly used vacuum pump is pumped to the ground, and then sent to a designated place for use with a compressor. The use of a water ring vacuum compressor serves two purposes and saves equipment costs.
At present, most of the mines use this type of equipment to draw gas. Since the mine gas is flammable and explosive, the use of a proper water ring vacuum compressor is very important for 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. Among the safety accidents in various mines, part of it is due to the mismatch between the drainage equipment and the actual environment of the mine, resulting in inadequate pumping capacity of the gas pump, resulting in the continuous accumulation of gas in the mine.
At present, the selection of vacuum compressors for gas drainage is generally determined directly by the coal mine design institute. Manufacturers provide equipment. The selection of the design institute is generally based on the gas pump selection formula in the mine gas drainage theory and technology. If the pipeline layout is long, the resistance is large, and the system negative pressure requirements are high, the formula selection accuracy is based on this formula. It is not very high. It is easy to cause the selected equipment to be inconsistent with the actual environment of the coal mine, failing to meet the mine's requirements for gas drainage and safety hazards. Based on years of experience in the application of vacuum compressor products in the coal mining industry and the many years of cooperation with the Institute of Design, we have proposed a new method for the selection and application of water ring vacuum compressors for the extraction of gas from coal mines to enable them to operate accurately and effectively. To ensure the safety of gas gas during the drainage process.
The following is a description of specific selection examples.
Example: A mine requires a gas mixing flow rate of 130IVm3/miri, a gas concentration of 30%, a negative pressure requirement of the drilling hole of 15000Pa, and the gas drainage system piping layout and the gas gas requirements for each pipeline are shown in the gas drainage diagram of the mine. The gas is pumped to a gas tank and sent to a residential area. The pressure required by the user at the gas outlet is required to be 5000 Pa, and the corresponding water ring vacuum compressor is selected.
2 Determination of parameters In the coal mine gas drainage, as long as determine the main parameters affecting the water ring vacuum compressor: vacuum degree (inhalation pressure), discharge pressure, pumping capacity, etc., you can determine the selected compressor model And specifications.
(1) System negative pressure, discharge pressure and system total resistance System negative pressure (vacuum) includes negative pressure in drilling and resistance loss of inlet pipeline to be overcome by the drainage equipment. Line loss includes frictional resistance and local resistance; The pressure includes the required pressure of the gas tank and the resistance loss of the discharge pipe; the total resistance of the system is the sum of the above two, and the formula of their mutual relations is: H-system total resistance; H system negative pressure, ie the suction vacuum degree of the water ring vacuum compressor Positive system pressure, ie vacuum compressor discharge pressure; H drilling - drilling negative pressure; H suction pipe maximum resistance loss; H gas pump exhaust pipe outlet positive pressure, including drain line resistance loss and gas tank requirements to achieve Pressure; H-suction pipe maximum frictional resistance loss; H stomach - suction pipe local resistance loss, according to the suction pipe maximum frictional resistance loss of 20%; K-spare coefficient, take 1.2.L-pipeline Length, m; Q-flow, mVmin; A- density ratio of mixed gas to air, gas concentration 30%, A=0.866; d-tube inner diameter, cm; k-coefficient of different tube diameter, d>150mm, k=0.71 Based on the above resistance formula, can be calculated In the figure, the frictional resistance loss of each pipe branch line is taken and the maximum frictional resistance value can be taken. The loss resistance of the discharge pipe line can also be calculated according to this, which can be calculated separately: This can determine the negative pressure of the system for coal mine gas drainage. 56216Pa, the discharge pressure 7136Pa, the total system resistance is 63352Pa, which is to ask the water ring vacuum compressor to overcome the 63352Pa total system resistance, including the suction vacuum is 56216Pa (absorbing absolute pressure is 45084Pa), the discharge pressure is 7136Pa. The system requires a gas drainage flow rate of 130Nm3/min, consider the spare coefficient K = 1.2, that requires the water ring vacuum compressor pumping capacity of 156Nm3/min, because the above calculation of the water ring vacuum compressor suction population vacuum is 56216Pa, Converted to the corresponding vacuum under the suction volume, and then through the exhaust pressure correction of the suction volume, you can determine the suction ring vacuum compressor suction volume. The calculation process is as follows: Flow conversion formula: human gas flow, NmVmin; P-atmospheric pressure, taking a standard atmospheric pressure calculation.
Since the discharge pressure of the water ring vacuum pump outlet is 7136 Pa, and the discharge pressure has little effect on the negative pressure of the system, it has an influence on the pumping capacity of the water ring vacuum compressor and the power of the operating shaft. Therefore, the empirical formula of the gas volume correction is determined by: It can be concluded that the performance parameters of the water ring vacuum compressor are as follows: According to the above three parameters, the model and specification of the water ring vacuum compressor to be selected can be determined; for example, if the company chooses the special water ring vacuum compression for the coal mine drainage gas The model of the machine is CBW1710,236r/min. 3 Summary After many years of practice and application in coal mine gas drainage, the water ring vacuum compressor selection method is simple, accurate and reliable, preventing coal mine gas drainage. Gas security risks caused by insufficient equipment capacity, and improved the operating efficiency of the water ring vacuum compressor.
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