At present, there are two types of vacuum pumps used in the water reverse osmosis treatment system in Shanghai: piston vacuum pump and centrifugal pump. These two types of vacuum pump technology are relatively mature, have been in the RO desalination system mature application.
China is a country with a serious shortage of water resources. Every year, about 25 billion m3 of water in China cannot be used due to pollution, and 24 billion m3 of groundwater is overdrawn, causing groundwater depletion; the economic loss caused by water crisis has accounted for about 23% of China’s GDP. However, seawater accounts for 96.5% of the total water volume of the earth, which is almost inexhaustible and inexhaustible. Therefore, it is an urgent and important task to develop cheap and large-scale desalination technology in China. Piston vacuum pump is one of the vacuum pumps. The practical application of vacuum pump in desalination can solve the problem of desalination.
Piston vacuum pump is the key equipment of desalination system, which provides the pressure needed for desalination of membrane system.
There are many factors to be considered in the selection of piston vacuum pump for desalination, such as operation efficiency, reliability, quality, noise, vibration and price, but the most important factor is the reliability and efficiency of the product. The energy consumption index of desalination system mainly depends on piston vacuum pump, lifting pump and energy recovery device. Piston vacuum pump is the main energy consumption equipment, and its power consumption accounts for about 335% of the system operation cost. Therefore, the operation efficiency of piston vacuum pump is one of the main factors affecting the water production cost of the product.
Piston vacuum pump is generally used in the situation of low rated flow. With the development of water pump technology, the maximum rated flow of piston vacuum pump can reach 140m / H3, the pressure can reach 85bar, and the efficiency can reach 90% – 94%. Therefore, the biggest advantage of piston vacuum pump is the low operating cost brought by high efficiency. Moreover, the flow rate of the piston vacuum pump can be kept stable when the pressure of the membrane is increased.
Desalination is the production of fresh water by desalination. The desalination treatment can ensure the stable water supply of coastal residents’ drinking water and industrial boiler make-up water. The reverse osmosis method is one of the main treatment technologies of seawater desalination at present. The reverse osmosis method is to separate the seawater from the fresh water by using the semi permeable membrane which only allows the solvent to pass through and does not allow the solute to pass through. In general, the fresh water diffuses to one side of the seawater through the semi permeable membrane. Because of the resistance of the semi permeable membrane, the liquid level on one side of the seawater gradually rises until it reaches a certain height, and this process stops For penetration. At this time, the static pressure of the water column on one side of the sea water is called osmotic pressure. If an external pressure greater than the osmotic pressure of seawater is applied to one side of seawater, the pure water in seawater will permeate into fresh water. The biggest advantage of RO method is to save the site and energy consumption.
Desalination is the production of fresh water by desalination of seawater. It is an open-source incremental technology to realize the utilization of water resources. It can increase the total amount of fresh water, and is not affected by time and space and climate. It has good water quality and reasonable price, and can guarantee the stable water supply for coastal residents and industrial boilers. The process of obtaining fresh water from seawater is called desalination. The practical application of vacuum pump in desalination is mainly to provide drinking water and agricultural water. Desalination is popular in the Middle East and is also used on some islands and ships.