How to choose the liquid ring vacuum pump is a problem that puzzles many enterprises. After purchasing the liquid ring vacuum pump, many enterprises will encounter various problems, such as the vacuum can not meet the demand, the pumping speed is too slow, the use of noise in relatively closed rooms is too big, or the oil mist can not be used normally when the pump is used. These problems are often related to type selection.
General enterprises may not understand the relationship between the parameters of the liquid ring vacuum pump and the actual use effect. Generally speaking, enterprises mainly consider the following factors when purchasing the liquid ring vacuum pump:
1. The specifications with lower rotational speed should be selected as far as possible.
At present, the application of liquid ring vacuum pump in our country is 2BE series at most, which belongs to the single action pump of axial suction and exhaust. There are many rotational speeds for the same specifications. When the inlet pressure is 200 hPa-600 hPa and the exhaust pressure is 800 hPa-1013 hPa, the linear speed of impeller blade outer circle should be 14-17 m/s. For larger specifications, the rotational speed of pump is lower because of the large diameter of impeller, so it achieves the same specifications. On the premise of sample pumping volume, the pump with lower rotational speed should be selected as far as possible, and the specific power consumed by the large pump is smaller, that is, the efficiency is higher.
In addition, the larger size liquid ring vacuum pump has a long blade, i.e. a long runner, a small curvature of the fluid, a straight streamline, a slowly variable flow, and a small energy loss caused by secondary eddy current and boundary layer.
2. The influence of water temperature should be considered.
Because the performance curves and technical data of domestic and foreign technical documents of liquid ring vacuum pumps are obtained on the premise that the inlet water temperature is 15 C, the formulas for calculating the influence coefficient of water temperature on gas volume when the water temperature is lower or higher than 15 C have been introduced.
Therefore, the effect of actual water temperature on gas flow should be fully considered when selecting liquid ring vacuum pump. Because the temperature of most users’supplementary water in our country is between 25 ~35 C. Therefore, when choosing a pump, the volume of gas on the technical documents should be increased appropriately.
3. The influence of inspiratory resistance
Because the gas suction location is often in the coal mine, far from the liquid ring vacuum pump (some coal mines reach several kilometers), and the suction pipeline is too long, the suction resistance loss should be fully considered. It can be calculated by the formula for calculating the suction resistance used in the coal mine system. When arranging the pipeline, the thicker suction pipeline should be used to reduce the resistance loss and the right angle elbow should be minimized. To achieve the purpose of improving the efficiency of inspiration.
4. Selection of Exhaust Gas with Micro-positive Pressure
At present, the exhaust gas of some coal mines is discharged far away or compressed into the gas storage tank, and the exhaust pressure is generally between 0.02 and 0.05 MPa.G. Because the performance curves and technical data in the technical documents of the liquid ring vacuum pump are obtained under the condition that the exhaust pressure is one standard atmospheric pressure, the influence of the increase of the exhaust pressure and the internal reflux of the pump chamber on the pumping volume should be taken into account in the selection of the pump.
In addition, as the exhaust pressure rises, the shaft power of the pump increases, and the power of the drive should also increase. In this case, the manufacturer should provide the test performance curve and the corresponding technical data in order to fully meet the user’s requirements.
Following is a detailed introduction of several EVP liquid ring vacuum pumps:
2BV Series Liquid Ring Vacuum Pump:operate steadily and the noise low to 62 dB.
2BE1 Series Liquid Ring Vacuum Pump：liquid ring vacuum pump with simple structure.
2BE3 Series Liquid Ring Vacuum Pump：liquid ring vacuum pumps, such as distribution plate, impeller and pump shaft are simplified in structure with performance improved, thus it’s very energy-saving.
DLV Series Double Stages Water Ring Vacuum Pumps：All kinds of models to fulfill various process requirements.
2SK Liquid Ring Vacuum Pump：Wide application range, which applicable for gas with vapor or flammable, explosive, containing a little dust and a little liquid gas.
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