Chemical centrifugal pumps and other centrifugal pump characteristics require distinction

The pump is a mechanical, chemical centrifugal pump that is one of them. It pumps the liquid through the impeller by centrifugal force and increases the mechanical energy of the liquid to transport the liquid. It is a machine that increases the liquid energy. Due to the special requirements of chemical production pump, chemical centrifugal pump compared with other centrifugal pump has the following characteristics:

1. To adapt to the needs of chemical processes Pumps in chemical production, not only to transport liquid materials and provide the necessary pressure on the process requirements, but also must ensure that the amount of materials transported in a certain chemical unit operation, requiring pump flow and lift to be stable , Keep the pump efficient and reliable operation. 2. Corrosion-resistant chemical pump delivery of media, including raw materials, reaction intermediates often more corrosive media. This requires the pump material selection is appropriate and reasonable, to ensure the safety of the pump, stable, long-life operation. 3. High temperature, low temperature chemical pump delivery of high temperature medium, the process liquid materials, but also the reaction process required and generated heat transfer liquid. For example: condensate pump, boiler feed pump, heat transfer oil pump. Chemical pump delivery of low temperature medium types are also many, such as: liquid oxygen, liquid nitrogen, methane, etc., the low temperature pump temperature mostly in a 20 ~ a 10 ℃. No matter the chemical pump conveying high temperature or low temperature, the selection and structure must be proper, and the sufficient intensity, the thermal shock resistance, the thermal expansion, the cold deformation and the cold brittleness of the designed and manufactured pump parts must be ensured. 4. Wear resistance, erosion resistance As the chemical pump delivery of logistics containing suspended solids, while the pump impeller, cavity and some high pressure and high flow rate under the pump parts of the surface protection is damaged, its life is shorter , So we must improve the chemical pump wear resistance, erosion resistance, which requires the use of pump material selection of wear-resistant manganese steel, ceramics, cast iron, the selection of erosion-resistant titanium, manganese steel. 5. Reliable operation Reliable operation of chemical pumps include two meanings: First, long-term operation without failure; Second, the operation of a variety of parameters stable. The reliability of the operation is crucial for chemical production. Frequent failure of the pump will not only result in frequent downtime but will also affect throughput and economic efficiency and may in some cases result in chemical system accidents. Chemical pump speed fluctuations, will cause flow and pump outlet pressure fluctuations, so that chemical production can not be normal or the reaction in the system affected, the material can not be balanced, not only resulting in waste, or even result in product quality degradation or product scrap. 6. No leakage or less leakage Chemical pump delivery of the majority of the medium for the flammable, explosive, toxic, harmful liquid, once the leak will seriously pollute the environment, endangering personal safety and the physical and mental health of workers, but also does not meet the leak-free factory and cleaning Civilized factory requirements, which must ensure that chemical pump operation does not leak, the pump seal on the use of new technologies and new materials, according to the rules of operation, high-quality maintenance. Liquid that can deliver critical-state liquid criticality tends to vaporize when the temperature rises or the pressure decreases. Chemical pumps sometimes transport critical liquid, once the liquid in the pump vaporized, prone to cavitation damage, which requires the pump has a high cavitation resistance. At the same time, the vaporization of the liquid may cause the frictional bonding of the static and dynamic parts of the pump, which requires that the clearance be made larger. In order to avoid the mechanical seal, packing seal, labyrinth seal and other damage caused by dry friction due to vaporization of the liquid, such chemical pumps must have a structure that adequately eliminates the gas that occurs in the pump. Pumps that deliver critical-state fluids can be made from materials that are self-lubricating, such as polytetrafluoroethylene, graphite, etc., for their shaft seal materials. For the shaft seal structure, in addition to packing seal, but also the use of double-sided mechanical seal or labyrinth seal. When the double-end mechanical seal is used, the cavity between the two end faces is filled with the external sealing liquid; when the labyrinth seal is adopted, a sealing gas with a certain pressure can be introduced from the outside. Sealing liquid or seal gas leak into the pump should be no harm to the pumping medium, if not leak into the atmosphere is also harmless. For example, when liquid helium in the critical state is delivered, methanol can be used as the sealing liquid in the cavity of the double-ended mechanical seal. Nitrogen gas can be introduced into the labyrinth seal when conveying vaporized liquid hydrocarbons.