Equipment and process for extracting helium from BOG gas with high hydrogen content

Abstract

The invention discloses equipment for extracting helium from BOG gas with high hydrogen content and a process thereof, and relates to the field of equipment and process for extracting helium from BOGgas. The equipment comprises a catalytic dehydrogenation reactor, a cooler, a molecular sieve dryer, a feed gas compressor, a heat exchanger, a membrane separator, a vacuum pump, a buffer tank, a crude helium compressor, a helium purifier, a helium supercharger, a digital display type gas supply busbar device and a helium bottle; according to the invention, the permeability coefficient of gas molecules is increased in a manner of before- membrane pressurization and after- membrane vacuumizing; relatively high yield and purity of helium are achieved by using a relatively small membrane area; ina membrane separation process for extracting concentrated crude helium from BOG feed gas, Non-phase change is realized, and the equipment investment and the operation cost are reduced; the recovery rate of helium is increased before desorbed gas of the helium purifier returns to the feed gas compressor, and the helium yield of the whole device is as high as 99%; an interface is additionally arranged on an original BOG fuel gas pipeline to concentrate helium in BOG feed gas, and the loss of impermeable gas passing through a membrane separator is lower than 5%.

Description

technical field [0001] The invention relates to the field of equipment and technology for extracting helium from BOG gas, in particular to equipment and technology for extracting helium from BOG gas with high hydrogen content. Background technique [0002] BOG gas refers to the non-condensable gas that cannot be liquefied or evaporated from the liquefied natural gas storage tank during the liquefaction of natural gas to produce LNG. The flow rate of BOG gas is considerable, accounting for about 8% of the raw gas flow at most. Therefore, LNG The production process will have a special recovery process to recover BOG gas. The common BOG recovery scheme for LNG is that the BOG gas in the LNG storage tank is compressed to medium pressure through the BOG compressor, part of the gas is burned as fuel gas, and the rest is passed through the BOG compressor. It is further compressed to the same pressure as the raw gas, and according to the conditions of the LNG device, it is merged ba...

AI Technical Summary

Problems solved by technology

First, impurities such as hydrogen sulfide, carbon dioxide, moisture, and even mercury in the helium-containing gas source must be purified before entering the cryogenic device, and then the natural gas is condensed twice to produce crude helium with a helium content of about 60%. Hydrogen, which is difficult to liquefy, is concentrated in crude helium with the concentration of helium, and needs to be removed before refining. In the process of removing hydrogen from crude helium, since the content of hydrogen reaches more than 10%, the crude helium The temperature rise in the hydrogen catalytic combustion process is high, which is not conducive to the control of the reaction. The commonly used method is to add excess air to dilute the concentration of hydrogen, or multi-stage catalytic combustion. The first process causes the concentration of helium to be diluted, requiring helium The gas is concentrated again, and the multi-stage hydrogen catalytic reactor of the second process has more equipment, large equipment investment and large floor area

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