1, the basic concept of cryogenic pump The general reference to the use of cryogenic pump medium temperature slightly higher at minus 30 ° C, low to minus 220 ° C, the designer should take into account the material's low temperature performance, impact resistance (mainly Ak), medium Of the physical and chemical properties, especially like liquid oxygen, liquid nitrogen, liquefied natural gas liquefaction of these media. Consider the sealing structure based on these properties. Such pumps are generally used packing seal. Seal cost is relatively low. Cryogenic pump is a special pump used to transport liquefied gas, such as liquid oxygen, liquefied natural gas and freezing liquid, liquid nitrogen in petroleum and chemical plants, so it is also called cryogenic system. 2 cryogenic pump type A. Piston, plunger Such pumps are generally used in gas filling, chemical processes (such as chemical reactors added high-pressure nitrogen, nitrogen dioxide, carbon dioxide, etc.), metallurgical works (steel mills in the steel gas, as a pump , The flow is generally not large centrifugal, but can effectively provide gas pressure) B. Centrifugal Centrifugal cryogenic liquid pumps are typically used to transport liquid from a cryogenic liquid vessel to another vessel or to use as a process pump in a space division (high flow rate). This pump is normally sealed using a mechanical seal or Labyrinth and other forms of sealing, sealing cost is relatively high. 3, the overall structural characteristics Vertical structure: suitable for buried in the ground, will not be affected by motor hot air, air temperature and sunshine, easy to keep cold; can reduce the pump suction height, increase perfusion head, improve the effective NPSH; vertical structure Is conducive to exhaust, the suspension shaft has enough height to facilitate the arrangement of shaft seal device, so the pump is also known as vertical cylinder pump. Symmetrical structure: The overall structure of the pump strives to be symmetrically arranged to allow uniform deformation in cold conditions. Double shell: In order to facilitate the cold and facilitate the transport of hazardous medium, usually made of double shells, the inner shell to withstand pumping pressure, the pressure between the inner shell is suction, which may be appropriate to reduce the strength requirements of the inner shell. 2, shaft seal Packing shaft seal: different from the ordinary type, using double packing seal, with a sealed chamber between the two layers, the introduction of a gas (such as nitrogen) from the outside world, from the sealing effect. Mechanical seal: mechanical seal is also different from the ordinary type, the use of double-ended mechanical seal, the seal chamber and the pump body with a buffer chamber, can play the role of cooling, while sealing the hydraulic pressure to adapt to discharge pressure changes for This, are generally equipped with a pressure device, chiller and other ancillary equipment. 3, the bearing: the bearing close to the atmospheric temperature, the general use of thrust ball bearings; the lower bearing for the sliding bearings, submerged in the working medium and run with the working medium for lubrication; in order to prevent the friction caused by heat and liquid vaporization, resulting in damage to lubrication, Good lubricity materials, such as tetrafluoroethylene, graphite, corrosion-resistant nickel alloy, etc .; with the journal bearings on the sliding bearing surface nitriding or surfacing cemented carbide. More keyword search: Cryogenic pump