Hydrogen purification

Claim 2

The process of claim 1 wherein the adsorption system comprises four separate adsorption beds.

Claim 3

The process of claim 1 wherein the operating pressure is 600 psia.

Claim 4

The process of claim 2 wherein the regenerating stream, after leaving the adsorption system, is recycled through the separation system for removal of contaminants therefrom thereby maximizing the purified hydrogen product yield.

Claim 5

In an integrated cryogenic-adsorption purification of a crude hydrogen stream containing contaminants selected from the group consisting of low boiling hydrocarbons, nitrogen, carbon monoxide, traces of argon and traces of oxygen to produce a purified hydrogen stream having in excess of 97 percent hydrogen which comprises a low temperature self-sustaining system including a series of cooling and condensing separation stages having successively lower temperatures wherein a liquid effluent is removed at each separation stage and expanded for use in indirect heat exchange with other streams coming from the previous steps in the system and wherein the hydrogen-rich vapor stream from the last separation stages enters an adsorption system wherein the improvement comprises: a. feeding the hydrogen-enriched vapor stream from the last separation stage to an adsorption system wherein said vapor stream is passed in parallel indirect heat exchange with the regenerant stream for said adsorption system prior to passing each stream to said adsorption system and wherein said vapor stream prior to entering said adsorption system also passes in indirect heat exchange with the product hydrogen and spent regenerating gas leaving said adsorption system; b. adsorbing, depressurizing, desorbing and pressurizing in the adsorption system under conditions of adiabatic pressure-swing cOnditions; c. operating said adsorption system such that pressure fluctuations throughout said process are minimized whereby the separate steps of adsorbing, depressurizing, desorbing and pressurizing take place with an overlapping of said steps to thereby insure smooth transitions between steps of different pressures; d. expanding the effluent streams from the adsorption system units to supplement the cooling requirements for the operation of the cryogenic process; e. recovering a gaseous hydrogen-rich product stream containing about 97 to 99.9 percent hydrogen.

Claim 6

The process of claim 6 wherein a portion of the hydrogen-rich product stream is used for desorbing after which it is recycled to the separation system for maximizing the yield of hydrogen.

Claim 7

An integrated cryogenic adsorption process for the purification of hydrogen by a low temperature, self-sustaining cooling and condensing separation system operating so as to provide for the stepwise removal of low boiling hydrocarbons, methane, nitrogen, carbon monoxide, traces of argon and traces of oxygen from a hydrogen containing gas feed through a series of cooling and condensing separation stages having successively lower temperatures wherein the lowest temperature reached is about 120* R thence through an adiabatic pressure-swing adsorption system maintained at a temperature of between about 160* R and 200* R and at a pressure between 300 and about 900 psia such that pressure fluctuations are minimized which comprises: a. passing said hydrogen feed through a first heat exchange means thereby cooling said feed; b. passing said cooled feed to a first separation zone; c. removing a first liquid bottoms containing methane and heavier hydrocarbons, expanding said first liquid bottoms and passing said expanded first liquid bottoms reversely through said first heat exchange means; d. removing said first separation zone a first vaporous overhead, passing said first vaporous overhead through a second heat exchange means thereby cooling said first overhead and passing said cooled first overhead to a second separation zone; e. removing a second liquid bottoms containing nitrogen, carbon monoxide and residual hydrocarbons from said second separation zone expanding said second bottoms and passing said expanded second bottoms reversely through said first and said second heat exchange means; f. removing a second vaporous overhead containing about 95 percent hydrogen, from said second separation zone passing said second overhead through a third heat exchange means thereby cooling said second overhead and passing said cooled second overhead to a third separation zone; g. removing a third liquid nitrogen rich bottoms from said third heat exchange zone expanding said third bottoms and passing said expanded third bottoms reversely through said third and said second and said first heat exchange means; h. removing a third overhead containing about 97 percent hydrogen from said third separation zone and passing said third overhead reversely through said third and said second heat exchange means; i. passing said third overhead from said second heat exchange means through a fourth heat exchange means; j. passing said third overhead from said fourth heat exchange means through an adsorption zone; k. removing a purified hydrogen stream containing about 97 to 99.9 percent by volume of hydrogen from said adsorption zone passing said purified stream reversely through said fourth and said second and said first heat exchange means; l. depressurizing said adsorption zone to reduce the pressure therein to about that of the expanded recycled purified hydrogen; m. recycling a portion of said purified hydrogen stream leaving said second heat exchange means, expanding said recycled hydrogen, passing said recycled hydrogen reversely through said third and said second heat exchange means, passing saiD recycled hydrogen reversely through said depressurized adsorption zone to desorb the nitrogen impurities, removing an impure recycled hydrogen stream from said adsorption zone passing said impure stream reversely through said fourth and said second and said first heat exchange means and recycling said impure stream to be combined with said hydrogen feed for removal of the nitrogen impurities therefrom; n. pressurizing said adsorption zone; and n. recovering said purified high pressure hydrogen.

Claim 8

The process of claim 8 wherein said third overhead and said recycled hydrogen are passed indirectly in parallel through a fifth heat exchanger before passing reversely through said third and said second heat exchangers.

Claim 9

The process of claim 8 wherein said depressurization pressure in said adsorption zone is about 35 psia.

Claim 10

The process of claim 8 wherein there are four adsorption zones being operated in cycles of about 30 minutes wherein one adsorbs while one depressurizes and one desorbs and one pressurizes under conditions of adiabatic pressure-swing.

Claim 11

The process of claim 11 wherein the separate stages are operated to overlap operation at the end of each cycle to insure a smooth transition within the system to thereby avoid pressure surges.

Claim 12

The process of claim 8 wherein the ratio of nitrogen to methane to carbon dioxide in the third overhead is such as to prevent solidification of said methane.

Claim 13

The process of claim 15 wherein the temperature of said third overhead after passing through said fifth third, second and fourth heat exchangers is raised within the cryogenic ranges.

Claim 14

The process of claim 8 wherein the adsorption zone is preferably operated between 140* and 175* R.

Claim 15

The process of claim 8 wherein said recycle hydrogen is expanded to a temperature of about 100* R.