Method and apparatus for displacement type pressure conveying of low-temperature liquefied gas

Abstract

The invention discloses a method and an apparatus for displacement type pressure conveying of a low-temperature liquefied gas. The method and the apparatus have the advantages that no low-temperature pump is needed for conveying the low-temperature liquefied gas to a high-pressure apparatus from a low-temperature liquefied gas, so that no energy is consumed, and a low-temperature storage tank also does not need to be supercharged and thus is prevented from overpressure and emission so that potential safety hazards and waste are prevented, and therefore, the energy source is saved and the ecological environment is protected. The apparatus comprises a displacement unit (44), a BOG (Boil Off Gas) treatment unit (45) and the low-temperature storage tank (24). The apparatus is low in apparatus investment, small in floor area, free of electric power, low in operation maintenance cost and high in safety.

Description

technical field [0001] The invention relates to the field of delivery of low-temperature liquefied gas, in particular, to a method and equipment with pumpless delivery. Such as liquid oxygen, liquid nitrogen, liquid argon, liquid hydrogen, liquid helium, liquefied natural gas (LNG) filling stations and filling stations, as well as gasification stations, LNG vehicle gas supply systems, etc. Background technique [0002] Cryogenic liquefied gas is a gas that exists in liquid form, and it is to cool down and liquefy the gas for the needs of storage and transportation. It has a low temperature (generally between -162°C and -256°C under normal pressure), a large gas-liquid ratio (that is, the volume ratio of a unit volume of low-temperature liquefied gas to gas that is vaporized into normal temperature and pressure), and high purity. Preservation is difficult (often due to poor thermal insulation performance of storage containers or production process requirements, gasification ...

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Problems solved by technology

[0004] 1. Energy consumption in the way of pumping: the power of cryopumps ranges from a dozen kilowatts to tens of kilowatts, and some sites even have to build dedicated substations for this purpose to meet the needs

Not only is the investment large and the area occupied is large, but the location of the construction site is also limited by the power supply, which increases the operating cost;

[0005] 2. The operation and maintenance cost of the pump delivery method is high, the reliability is relatively low, and the service life is limited

[0006] 3. Large investment in pump transportation: due to various technical reasons, the stability of domestic cryopumps cannot meet the requirements, and they mainly rely on imports

It can be released into the atmosphere, but it is uneconomical and damages the ecological environment; recycling the gas to the storage tank in the station will inevitably pressurize the storage tank

[0014] 6. Pressure delivery mode, low boosting efficiency: In the traditional pressurized delivery process, regardless of the size of the storage tank, the entire low-temperature storage tank is often pressurized, the pressurized space is large, and the amount of gasified low-temperature liquefied gas is large, increasing The pressure time is long and the efficiency is low; moreover, during the pressurization process, the supercooled low-temperature liquid exchanges heat with the gas in the gas phase, which causes the pressure of the low-temperature storage tank to drop, and continues to increase the amount of gasification, thereby increasing the heat input of the pressurization

[0015] In the production of cryogenic liquefied gas, people spend a lot of energy to cool down and liquefy the gas for storage and transportation, and in the production process, we invest expensive equipment and energy, so that the direct input of heat (such as pressurization) makes It heats up, makes it difficult to store and transport, and is a bad deal

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