(1) Chemical pump can meet the needs of chemical process
In the chemical production, the pump not only needs to transport the liquid material and provide the necessary pressure required by the process, but also must ensure the amount of material to be transported. In a certain chemical unit operation, the flow and head of the pump should be stable, and the pump should be operated with high efficiency and reliability.
(2) Corrosion resistance
The medium transported by chemical pumps, including raw materials and reaction intermediates, is often corrosive. This requires proper and reasonable material selection of the pump to ensure safe, stable and long-life operation of the pump.
(3) High temperature resistance and low temperature
The high-temperature medium transported by the chemical pump has a process liquid material, and also has a heat-carrying liquid required and generated by the reaction process. For example: condensate pump, boiler feed pump, heat transfer oil pump. There are many types of cryogenic media delivered by chemical pumps, such as liquid oxygen, liquid nitrogen, methane, etc. The low temperature operating temperature of the pump is mostly at 20~10 °C. Regardless of the chemical pump that delivers high or low temperature, the material and structure must be appropriate, and must have sufficient strength. The parts of the pump designed and manufactured can be affected by thermal shock resistance, thermal expansion, cold deformation, cold brittleness and the like.
(4) Wear and wash resistance
Since the chemical pump transports the suspended solid particles, and the impeller and the cavity of the pump also work under high pressure and high flow rate, the surface protective layer of the pump parts is destroyed and its life is short, so it is necessary to improve the resistance of the chemical pump. Grinding and scouring resistance, this requires the pump material to be made of wear-resistant manganese steel, ceramics, cast iron, etc., and the use of scouring titanium and manganese steel.
(5) Reliable operation
The reliable operation of the chemical pump includes two meanings: one is that the long-cycle operation does not fail; the other is that the various parameters are stable during operation. The reliability of operation is critical to chemical production. If the pump fails frequently, it will not only cause frequent production stoppages, but also affect production and economic benefits, and sometimes it may cause accidents in the chemical system. The fluctuation of the speed of the chemical pump will cause the fluctuation of the flow rate and the pressure of the pump outlet, so that the chemical production can not be carried out normally or the reaction in the system is affected, the material can not be balanced, which not only causes waste, but also causes the product quality to drop or the product to be scrapped.
(6) No leakage or less leakage
Most of the media transported by chemical pumps are flammable, explosive, toxic and harmful liquids. Once leaked, it will seriously pollute the environment, endangering personal safety and the physical and mental health of employees, and is even less in line with the requirements of non-leakage factories and clean and civilized factories. It is necessary to ensure that the chemical pump does not leak during operation, adopt new technology and new materials on the seal of the pump, operate according to the regulations, and maintain high quality.
(7) A liquid capable of transporting a critical state
A critical state of liquid tends to vaporize when the temperature rises or the pressure drops. Chemical pumps sometimes transport critical liquids. Once the liquid is vaporized in the pump, it is prone to cavitation damage, which requires the pump to have high cavitation resistance. At the same time, the vaporization of the liquid may cause frictional bonding of the static and dynamic parts of the pump, which requires the gap to be larger. In order to avoid mechanical seals, packing seals, labyrinth seals, and the like from being destroyed by dry friction due to vaporization of the liquid, such chemical pumps must have a structure that sufficiently removes gas generated in the pump. For the pump for conveying critical state liquid, the shaft sealing material may be made of a material having good self-lubricating properties, such as polytetrafluoroethylene or graphite. For the shaft seal structure, in addition to the packing seal, a double mechanical seal or a labyrinth seal can be used. When the double-face mechanical seal is used, the cavity between the end faces is filled with the sealed liquid; when the labyrinth seal is used, the seal gas having a certain pressure can be introduced from the outside. When the sealing liquid or sealing gas leaks into the pump, it should be possible to pump the medium, and it is harmless if it leaks into the atmosphere. For example, when liquid helium is transported in a critical state, methanol can be used as a sealing liquid in the cavity of the double-face mechanical seal; when liquid hydrocarbons that are easily vaporized are transported, nitrogen gas can be introduced into the labyrinth seal.
