What is the difference between chemical pumps and ordinary centrifugal pumps?
(1) In chemical production, to meet the needs of chemical processes, it is not only necessary to transport liquid materials, but also to provide the necessary pressure required by the process and ensure the amount of materials transported. In the operation of a certain chemical unit, the flow rate and head of the pump should be stable, and the efficient and reliable operation of the pump should be maintained.
(2) The medium transported by corrosion-resistant chemical pumps, including raw materials, reaction intermediates, etc., is often corrosive. This requires the material selection of the pump to be appropriate and reasonable, ensuring the safe, stable, and long-lasting operation of the pump.
(3) High temperature and low-temperature chemical pumps transport high-temperature media, including process liquid materials and heat transfer liquids required for reaction processes. For example: condensate pump, boiler feedwater pump, heat transfer oil pump. There are various types of low-temperature media transported by chemical pumps, such as liquid oxygen, liquid nitrogen, methane, etc. The low-temperature working temperature of pumps is mostly 120-110 ℃. Whether transporting high-temperature or low-temperature chemical pumps, the material selection and structure must be appropriate and have sufficient strength. The pump components designed and manufactured can resist thermal shock, thermal expansion, low-temperature cold deformation, and cold brittleness.
(4) Wear resistant and erosion resistant: Due to the presence of suspended solid particles in the logistics of chemical pumps, as well as the operation of pump impellers and chambers under high pressure and high flow rate, the surface protective layer of pump components is damaged and the service life is short. Therefore, it is necessary to improve the wear resistance and erosion resistance of chemical pumps. Pump materials such as wear-resistant manganese steel, ceramics, cast iron, erosion resistant titanium, manganese steel, etc. are required to be selected.
(5) The reliable operation of chemical pumps includes two meanings: one is long-term operation without faults; Secondly, various parameters remain stable during operation. Reliability is crucial for chemical production. If the pump frequently malfunctions, it will not only lead to frequent shutdowns, affecting production and economic benefits, but sometimes also cause accidents in the chemical system. The fluctuation of chemical pump speed can cause fluctuations in pump outlet flow rate and pressure, affecting the normal progress of chemical production or reactions in the system, causing material imbalance, not only causing waste, but also reducing product quality or scrapping products.
(6) The media transported by chemical pumps are mostly flammable, explosive, toxic, and harmful liquids. Once leaked, it will seriously pollute the environment, endanger personal safety and the physical and mental health of employees, and does not meet the requirements of a leak free factory and a clean and civilized factory. Therefore, it is necessary to ensure that the chemical pump does not leak during operation. The pump seal adopts new technology and materials, operates according to regulations, and maintains high quality.
(7) When the temperature increases or the pressure decreases, critical liquids that can transport critical liquids often vaporize. Chemical pumps sometimes transport critical liquids, and once the liquid evaporates inside the pump, it is prone to cavitation damage, which requires the pump to have high resistance to cavitation. Meanwhile, the evaporation of liquid may cause friction and adhesion between the moving and stationary parts inside the pump, which requires a larger gap. To avoid damage to mechanical seals, packing seals, labyrinth seals, etc. due to dry friction caused by liquid evaporation, this chemical pump must have a structure for the gas inside the pump.
The shaft seal material for pumps transporting critical liquids can use materials with good self-lubricating properties such as polytetrafluoroethylene and graphite. In addition to packing sealing, the shaft seal structure can also use double end mechanical seals or labyrinth seals. When using a double end mechanical seal, the space between the two end faces is filled with external sealing liquid; When sealing a maze, a sealing gas of a certain pressure can be introduced from the outside. When sealing liquid or sealing gas leaks into the pump, the pumping medium should be harmless, and if leaked into the atmosphere, it should also be harmless. When transporting critical liquid helium, methanol can be used as the sealing liquid in the double end mechanical seal chamber; When transporting easily vaporized liquid hydrocarbons, nitrogen can be introduced into the labyrinth seal.
