The liquid ring vacuum pump is very popular and widely used in various industries. Today, for example, how to choose the appropriate liquid ring vacuum pump in the paper industry production, many customers say that the selection of liquid ring vacuum pump is very complicated. In fact, we only need to adhere to the following principles, we can easily achieve the reasonable configuration of liquid ring vacuum pump, make the right selection, let’s take a look at it together. Right.
First, choose energy-saving liquid ring vacuum pump.
At present, there are several series of liquid ring vacuum pumps suitable for papermaking industry at home and abroad, such as 2be, 2BV, DLV, etc. through the development of new products for liquid ring vacuum pumps in crude and low vacuum industry in recent years, the efficiency of liquid ring vacuum pumps has been greatly improved. The liquid ring vacuum pump, under the condition of experimental station, can reach the highest efficiency of 67%, which will have higher efficiency when it is used in paper mill. The technology is indeed efficient and energy-saving, and the new technology also brings new changes.
Second, choose low speed liquid ring vacuum pump.
The efficiency of liquid ring vacuum pump is directly related to the rotating speed, the relationship between the air volume and the rotating speed is in the first power, while the relationship between the shaft power and the rotating speed is in the second power when the rotating speed is too high. When the rotating speed is increased by 10%, the gas volume is also increased by 10%, while the shaft power is increased by about 20%. Therefore, the liquid ring vacuum pump with low rotating speed should be selected as far as possible. It is better to choose the corresponding speed when the linear speed at the end of the impeller blade is below 18m / s. at this time, the efficiency of the pump is usually higher. Of course, relative to the higher speed of the pump will pay more purchase costs, relative to the cumulative energy consumption, in the context of increasing emphasis on energy saving, it is obviously worthwhile to choose low-speed energy-saving vacuum pump.
Third, the combination of vacuum points is reasonable.
The vacuum degree and the vacuum point close to the space position should be combined together, and a larger vacuum pump should be used for suction. The combination should be considered to be conducive to the pipeline layout, and the combination should be different from each functional area. When the air volume is similar and the vacuum degree is different, the pump with diaphragm can be selected. For example, between the suction boxes of the upper and lower woollen cloth and between the different vacuum suction rollers, pumps with baffles can be selected.
Fourth, the air volume at the combined point of vacuum pump shall be converted.
Because the gas is compressible, the volume of the gas will expand when the high pressure gas is reduced to the low pressure gas. If it is necessary to combine the high vacuum chamber and the low vacuum chamber of the vacuum couch, the vacuum degree and gas volume of the high vacuum chamber are – 65kpa and 80m3 / min respectively, and the vacuum degree and gas volume of the low vacuum chamber are – 40kpa and 50m3 / min respectively, then the gas volume of the low vacuum chamber shall be converted to the gas volume at – 65kpa first, and the calculated gas volume is 84.4m3/min ((101.3-40) / (101.3-65) X50 = 84.4), then the gas volume of the selected pump shall be 164.4m3 /Min, instead of selecting a pump with a gas volume of 130m3 / min.
Fifth, the pipeline loss of vacuum pump should be properly considered.
There will be a certain pipeline loss when the gas pumped from each vacuum element flows in the pipeline, which will cause the pressure of the gas to decrease and the volume to expand. In the case of reasonable pipeline size design, the pipeline loss can be taken as 2-3kpa (low value for high vacuum and high value for low vacuum).
Sixth, the medium temperature correction should be appropriate.
Because the air pumped by the vacuum pump on paper machine is wet air with higher temperature, and the working fluid of the liquid ring vacuum pump has higher water temperature because of various restrictions, which is inconsistent with the working condition calibrated on the performance curve of the liquid ring vacuum pump, so the temperature and water temperature need to be corrected. When the air temperature is higher and the water temperature is lower, the corrected air volume will be smaller and the selected pump will be smaller, otherwise the selected pump will be larger. The specific temperature to be taken for correction shall be determined by the parameters of the paper machine and the specific conditions of the paper mill. Generally, it is feasible to take the temperature of 45 ℃ and the temperature of 35 ℃ for correction, so the correction result is safe and reliable.
The above are the six important considerations for the selection of liquid ring vacuum pump in the papermaking industry. Many customers will compare the imported pump with the domestic pump. As we said in the second point, selecting the pump with higher speed will pay more purchase cost and higher efficiency. However, no matter the domestic pump or the imported pump, it is necessary to operate the vacuum pump correctly according to the use method of the vacuum pump, so as to make the pump more efficient. Longer life.