Method for liquefaction of industrial gas by integration of methanol plant and air separation unit

A method for the liquefaction of an industrial gas, the method comprising the steps of:

• (a) providing a pressurized natural gas stream, a pressurized purge gas stream originating from a methanol plant, and a pressurized air gas stream comprising an air gas from an air separation unit (ASU), wherein the pressurized purge gas stream is comprised predominately of hydrogen, wherein the pressurized air gas stream has an oxygen concentration at or below that of atmospheric air;
• (b) expanding a first portion of the pressurized natural gas stream to produce an expanded natural gas stream, expanding the pressurized purge gas stream to produce an expanded purge gas stream, and expanding the pressurized air gas stream to produce an expanded air gas stream;
• and
• (c) liquefying the industrial gas in a liquefaction unit against the expanded natural gas stream, the expanded purge gas stream, and the expanded air gas stream to produce a liquefied industrial gas stream,
• wherein the industrial gas to be liquefied is selected from the group consisting of a second portion of the pressurized natural gas stream, a nitrogen gas stream from a nitrogen pipeline, a nitrogen gas stream from the ASU, hydrogen and combinations thereof.

A method for the liquefaction of an industrial gas selected from the group consisting of nitrogen, natural gas, hydrogen and combinations thereof, the method comprising the steps of:

• a) withdrawing a natural gas stream from a natural gas pipeline;
• b) sending a first portion of the natural gas stream to a methanol production facility under conditions effective for producing a methanol stream, a purified hydrogen stream, and a purge gas rich in hydrogen;
• c) expanding a second portion of the natural gas stream to form an expanded natural gas stream;
• d) expanding the purge gas rich in hydrogen from step b) to form an expanded hydrogen stream;
• e) expanding a pressurized air gas stream from or derived from an air separation unit (ASU) to form an expanded air gas stream, wherein the air gas from or derived from an ASU is a gas stream selected from the group consisting of compressed and purified air from a main air compressor (MAC), a nitrogen stream from a medium pressure column, and combinations thereof;
• f) cooling the industrial gas in a heat exchanger against the expanded natural gas stream and the expanded hydrogen stream;
• and
• g) further cooling and liquefying the industrial gas in the heat exchanger against the expanded air gas stream to produce a liquefied industrial gas.