Liquid nitrogen washing device with function of producing natural gas

Abstract

The invention discloses a liquid nitrogen washing device with a function of producing natural gas, which comprises a first feed gas cooler 1, a second feed gas cooler 2, a nitrogen washing tower 3, a purifying synthesis gas pipe and a demethanizer 3, wherein the purifying synthesis gas pipe runs through the first feed gas cooler 1 and the second feed gas cooler 2 in sequence; the demethanizer 3 is provided with an air inlet end, an air outlet end and a fraction output end; the purifying synthesis gas pipe is communicated with the air inlet end after running through the second feed gas cooler; and the air outlet end is communicated with the nitrogen washing tower 3 through a pipe. The liquid nitrogen washing device with the function of producing natural gas is capable of recycling methane generated during the process of coal gasification and manufacturing the methane into natural gas, which not only realizes the goal of obtaining clean natural gas containing about 99% of methane while producing refined ammonia synthesis gas, but also adds a new product variety and increases the business opportunity of a factory.

Description

technical field [0001] The invention relates to the field of coal chemical industry, and relates to a synthesis gas refining process for producing synthetic ammonia, in particular to a liquid nitrogen washing device for concurrently producing natural gas. Background technique [0002] Coal is passed through the gasification section to obtain crude gas, and the crude gas enters the low-temperature methanol washing device after the transformation section, and the purified synthesis gas is obtained after the acid gas is removed in the low-temperature methanol washing device, and the purified syngas enters the liquid nitrogen washing device to remove trace CO, etc. Synthetic gas, the raw material for synthetic ammonia, is obtained. [0003] At present, the domestic "liquid nitrogen washing device" used in the field of coal chemical industry to produce synthetic ammonia and refine syngas is all used to remove and purify CO in syngas. But while washing off CO, CH 4 and Ar are al...

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Problems solved by technology

[0010] The object of the present invention is exactly to solve when CH in the purified syngas Content ≥ 1% or higher (as Lurgi pressurized gasification, KBR pressurized gasification, or other gasification methods etc. contain about 2 % (dry basis) and above methane), methane solidifies and freezes in the cold box of the liquid nitrogen washing device, causing the problem that the liquid nitrogen washing device cannot operate normally. It is a clean fuel - natural gas, which is called "LNG" (liquefied natural gas) after liquefaction

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