A kind of antifreeze blocking co-production lng liquid nitrogen washing device and method combined with mixed refrigerant system

Abstract

The invention discloses a liquid nitrogen washing device for anti-freeze blockage and co-production of LNG combined with a mixed refrigerant system and a method thereof. The invention is mainly composed of a molecular sieve adsorption system, a cold box separation and liquefaction system and a mixed refrigerant refrigeration cycle system. The molecular sieve system is mainly composed of an adsorber and a regeneration system. The mature liquid nitrogen washing molecular sieve adsorption technology is used to remove carbon dioxide and methanol; the mixed refrigerant system is mainly composed of a compressor unit and a refrigerant storage and distribution unit. The compressor uses a single MRC Centrifugal compressor, low energy consumption, simple equipment, stable and reliable; cold box system is mainly composed of plate-fin heat exchanger group, nitrogen washing tower and methane distillation tower. The present invention accepts the purified gas from the upstream low-temperature methanol washing process, and removes CO and CH in it. 4 , Ar and other impurities are prepared into pure synthesis gas with H2 / N2=3:1 to synthesize ammonia, and the separated methane-rich liquid is separated by a rectification tower to obtain LNG, which is sent to the LNG tank area outside the boundary.

Description

technical field [0001] The invention relates to a chemical cryogenic purification and separation device, in particular to an anti-freeze blockage co-production LNG liquid nitrogen washing device combined with a mixed refrigerant system and a method thereof. Background technique [0002] Natural gas processing devices mostly use low-temperature condensation method to condense and separate natural gas. Many parts of the device are in a low temperature state of -20°C-89°C under normal operation. Slight freezing makes the pipeline blockage and affects the start-up and normal production of the device. , Seriously freeze and crack equipment, pipelines and valves, which may cause a large amount of natural gas leakage, causing a series of accidents such as personal poisoning, equipment explosion, and fire. [0003] The formation of natural gas hydrate is not only related to the composition of natural gas and free water content, but also requires certain thermodynamic conditions, nam...

AI Technical Summary

Problems solved by technology

[0006] Conventional liquid nitrogen washing is to provide cooling capacity by throttling high-pressure nitrogen gas and adding liquid nitrogen externally, which requires a large amount of liquid nitrogen consumption

Moreover, the conventional nitrogen washing tower does not have a bottom rectification part, and the raw material gas directly enters the bottom of the tower, which is prone to freezing and blocking problems of condensed gases such as methane and carbon dioxide.

At present, many companies usually divide liquid nitrogen washing and purification of syngas and LNG into two systems, which not only take up a lot of space, but also have low efficiency and high energy consumption.

Images