What are the differences between the chemical pump and the ordinary centrifugal pump?
(1) to meet the needs of chemical process pumps in chemical industry, not only to the necessary pressure conveying liquid material and process requirements to provide, it must ensure that the amount of material delivery, in certain chemical unit operation, the requirements of the pump flow and head to maintain a stable, high efficiency and reliable operation of the pump.
(2) the medium which is conveyed by the corrosion resistant chemical pump, including the raw material and the reaction intermediate, is often more corrosive medium. This requires the appropriate and reasonable selection of the material of the pump to ensure the safety and stability of the pump, and the fate of the long life.
(3) high temperature and low temperature chemical pump transport high temperature medium, the process liquid material, also have the reaction process required and produced hot liquid. For example: condensate pump, boiler feed water pump, heat transfer oil pump. There are many kinds of low temperature medium for the chemical pump, such as liquid oxygen, liquid nitrogen, methane, and so on. The low temperature working temperature of the pump is mostly at one 20~ and 10 degrees C. No matter how high temperature or low temperature chemical pumps are transported, the material and structure must be appropriate and must have enough strength. The parts of the pump designed and manufactured can be impacted by heat shock, thermal expansion, low temperature cold deformation, cold brittleness and so on.
(4) abrasion and erosion resistance due to the presence of suspended solid particles chemical pump delivery of logistics, while the pump impeller chamber and some work under high pressure high flow rate, pump parts surface protection layer is damaged, the service life is short, so we must improve the chemical pump wear resistance, resistance to erosion, which the requirements of the pump material selection of wear-resistant steel, ceramics, cast iron, use erosion resistant titanium, manganese, etc..
(5) the operation of the reliable operation of the reliable chemical pump includes two meanings: one is the long period running without failure, and the two is the smooth operation of various parameters. The reliability of the operation is very important to the chemical production. If a pump often fails, it will not only cause frequent shutdown, but also affect production and economic benefits, and sometimes it may cause accidents in chemical systems. The fluctuation of chemical pump speed will cause the fluctuation of discharge and pump outlet pressure, so that chemical production can not be carried out normally or the reaction in the system is affected, and the material can not be balanced, which will not only cause waste, but also cause the quality of products to decline, or the products will be scrapped.
(6) no leakage or less leakage of most chemical pump delivery of flammable, explosive and poisonous liquid, once the leak will seriously pollute the environment, endanger the safety and health of the staff, but do not meet the factory and no leakage clean and civilized factory requirements, which must ensure that no leakage of chemical pump operation when using the new technology and new materials in the pump seals, according to operating procedures, quality maintenance.
(7) a liquid that can transport critical state of a critical state is often vaporized when the temperature is raised or the pressure is reduced. Chemical pumps sometimes deliver critical state liquids. Once liquids are vaporized in pumps, it is easy to cause cavitation damage, which requires pumps to have high cavitation resistance. At the same time, the vaporization of the liquid may cause friction in the static part of the pump, which requires a larger gap. To avoid damage due to dry friction due to the vaporization of liquids, mechanical seals, packing seals and labyrinth seals must be removed.
The pump of the critical state liquid can be used as the material with good self lubrication, such as polytetrafluoroethylene and graphite. For the shaft seal structure, besides the packing seal, the double end mechanical seal or the labyrinth seal can be used. When a double face mechanical seal is applied, the external sealing fluid is filled in the cavity between the two ends. When the labyrinth seal is applied, a sealed gas with certain pressure can be introduced from the outside. When sealing liquid or sealed gas leak into the pump, the pump medium should be no harm, if the leakage into the atmosphere is also harmless. Such as the transportation of critical state of liquid helium, the double mechanical seal the cavity can be used for sealing liquid methanol; delivery easy to vaporization of liquid hydrocarbon, the labyrinth seal can be the introduction of nitrogen.
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