Multi-stage nitrogen recovery system and recovery method

Abstract

The invention discloses a multi-stage nitrogen recovery system and a recovery method. The system sequentially comprises a first-stage recovery system and a second-stage recovery system. The first-stage recovery system utilizes the dissolution-diffusion principle, namely molecules move towards the chemical potential reduction direction through a membrane, and because the speeds of gas with different components in mixed gas passing through the membrane are different, the purposes of gas separation and gas recovery are achieved. Molecules of nitrogen are different from olefin and hydrogen molecules, and the purity of nitrogen subjected to multistage separation can reach 99% or above. An unpowered expansion cryogenic technology is adopted in the second-stage recovery system, wherein gas with certain pressure is subjected to adiabatic expansion in an expansion machine to do work outwards to consume the internal energy of the gas, so that the gas is cooled intensively to achieve the purposeof refrigeration, nitrogen is liquefied and recycled, and the low temperature can be generated without any external energy consumption or power. The multi-stage nitrogen recovery system and the methodhave the advantages of a simple structure, a simple flow, a low cost, economy, environmental protection and the like.

Description

technical field [0001] The invention relates to the field of nitrogen recovery, in particular to a multistage nitrogen recovery system and recovery method. Background technique [0002] At present, in the production process of plastic factories, organic synthesis factories and petrochemical factories, a large amount of nitrogen is used as an inert protective gas for production equipment. The used nitrogen becomes non-recyclable gas due to the presence of heterohydrocarbons, hydrogen, etc., resulting in a huge waste of resources. At the same time, the device must re-produce and provide a large amount of nitrogen during daily operation, and the production of nitrogen requires a lot of power resources. , energy consumption is becoming more and more serious. [0003] In this context, the common method in the prior art is to choose to treat this kind of tail gas by incineration, and remove the hydrocarbons and hydrogen in the tail gas by burning, which will cause (hydrocarbons, ...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the deficiencies in the prior art, the present invention provides a multi-stage nitrogen recovery system, which solves the waste and pollution of nitrogen recovery resources in the prior art

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