Exhaust gas recovery and utilization method for producing liquefied natural gas from coke oven gas

Abstract

The invention discloses a tail gas recovery and utilization method for producing liquefied natural gas from coke oven gas, which comprises the following steps of: dividing nitrogen gas and hydrogen tail gas separated and discharged from the top of a dehydrogenation tower and a rectification tower into two paths; one of them is connected with a flare venting pipeline, the other is connected to a gas supply source pipeline of coke oven gas, and installing sampling pipelines on the two pipelines; sampling the gas on the sampling pipeline; performing composition analysis of the sampled gas; according to the gas analysis results on the two pipelines, adjusting the control valves on the process transformation pipelines until the gas composition fluctuation of coke oven gas in the gas supply pipeline remains within a normal and reasonable range. The invention not only realizes the effective adjustment of the gas components in the production system, ensures the stability of the production of the system, but also realizes the reasonable recovery and utilization of the tail gas from the production of liquefied natural gas by the coke oven gas, increases the output and saves the production cost.

Description

technical field [0001] The invention relates to the technical field of liquefied natural gas preparation, in particular to a tail gas recycling method for producing liquefied natural gas from coke oven gas. Background technique [0002] Coke oven gas, also known as coke oven gas, belongs to high calorific value gas, crude gas or raw gas due to its many combustible components. It refers to a kind of flammable gas produced by coke and tar products after high-temperature dry distillation in the coke oven by making coking coal with several kinds of bituminous coal. Coke oven gas is the main raw material gas for the production of liquefied natural gas. , in the process of producing liquefied natural gas, hydrogen and carbon dioxide are reacted to produce methane through catalytic chemical reaction, and then condensed by a cooling device to prepare liquefied natural gas. The cryogenic liquefaction separation system of the LNG device adopts mixed refrigerant refrigeration, double ...

AI Technical Summary

Problems solved by technology

After the methanation gas is dehydrated and dried, it is first pre-cooled by Freon, and then enters the heat exchangers in each section of the cold box, and is cooled by the low-temperature medium that flows back. After the gas is cooled to a certain temperature, it becomes a mixture of gas and liquid. In the middle of the rectification tower, the gas is rectified in the rectification tower, and hydrogen and nitrogen are separated and discharged from the top of the tower, and liquid methane is obtained at the bottom of the tower, which is supercooled by a cooler and depressurized, and then sent to an atmospheric pressure LNG storage tank for storage , the H2-N2 mixed tail gas discharged from the top of the tower is discharged to the torch for combustion and evacuation. This evacuation will undoubtedly cause a waste of energy. , nor can the stable production of the production process

Images