PROCESS FOR PRODUCING HYDROGEN GAS FROM THE CATALYTIC CRACKING OF AMMONIA
Process A process for producing hydrogen gas from the catalytic cracking of ammonia. The process comprises the step of supplying a hydrogen containing recycle gas taken from downstream of an ammonia cracking reactor to one or more catalyst containing reaction tubes disposed within the ammonia cracking reactor. The invention may be used to provide hydrogen gas as a non-carbon containing fuel.
1 . A process for the catalytic cracking of ammonia, the process comprising:
supplying an ammonia stream to one or more catalyst containing reaction tubes disposed within an ammonia cracking reactor;
cracking the ammonia in the ammonia stream in the one or more catalyst containing reaction tubes disposed within the ammonia cracking reactor to produce a hydrogen containing stream; and
supplying a hydrogen containing recycle gas taken from downstream of the ammonia cracking reactor to the one or more catalyst containing reaction tubes disposed within the ammonia cracking reactor.
2 . The process according to claim 1 , comprising the step of pre-heating the ammonia stream to a temperature of from 350° C. to 1000° C.
3 . The process according to claim 1 , wherein the pressure inlet to the one or more reaction tubes is in the range of 1 to 100 bar absolute, 10 to 90 bar absolute, or 31 to 51 bar absolute.
4 . The process according to claim 1 , wherein the hydrogen containing stream comprises from 40 mol % to 75 mol % H 2 .
5 . The process according to claim 1 , wherein the hydrogen containing recycle gas is supplied to the one or more reaction tubes disposed within the ammonia cracking reactor such that from 0.5 mol % to 50 mol % H 2 , from 1 mol % to 40 mol % H 2 , from 2 mol % to 30 mol % H 2 , from 4 mol % to 20 mol % H 2 , or 5 mol % to 10 mol % H 2 is supplied to the one or more reaction tubes.
6 . The process according to claim 1 , wherein the process further comprises the step of feeding the hydrogen containing stream to a purification unit and increasing the H 2 content of the hydrogen containing stream to produce an enriched hydrogen stream and a tail gas.
7 . The process according to claim 6 , wherein the enriched hydrogen stream comprises from 50 mol % to 100 mol % H 2 , from 60 mol % to 90 mol % H 2 , or from 70 mol % to 80 mol % H 2 .
8 . The process according to claim 1 , wherein the hydrogen containing recycle gas comprises a portion of the hydrogen containing stream.
9 . The process according to claim 1 , wherein the hydrogen containing recycle gas comprises a portion of the enriched hydrogen containing stream, and/or a portion of the tail gas from the purification unit.
10 . The process according to claim 1 , comprising the step of combusting one or more fuel streams with oxygen in a fuel combustion zone to provide heat energy to support the endothermic ammonia cracking reaction in the ammonia cracking reactor.
11 . The process according to claim 10 , wherein the one or more fuel streams comprise one or more of hydrogen, natural gas, methane, refinery off gas, biogas, the tail gas from the hydrogen purification unit, a portion of the hydrogen containing stream from the ammonia cracking reactor, or a portion of the enriched hydrogen containing stream from the purification unit.
12 . The process according to claim 10 , wherein the one or more fuel streams comprise hydrogen in an amount of from 10 mol % to 45 mol %, from 12 mol % to 35 mol %, or from 15 mol % to 25 mol %.
13 . The process according to claim 10 , wherein the one or more fuel streams comprise ammonia in an amount of from 10 mol % to 45 mol %.
14 . The process according to claim 10 , wherein the one or more fuel streams are pre-heated to a temperature of from 100° C. to the auto ignition temperature of the fuel stream prior to being combusted in the fuel combustion zone.
15 . The process according to claim 6 , wherein the tail gas comprises from 1 mol % to 50 mol % H 2 , from 2 mol % to 40 mol % H 2 , or from 15 mol % to 25 mol % H 2 .
16 . The process according to claim 1 , wherein the one or more catalyst containing tubes are formed of an iron based alloy, a nickel based alloy, or a cobalt based alloy.
17 . A process for the catalytic cracking of ammonia, the process comprising:
supplying an ammonia stream to one or more catalyst containing reaction tubes disposed within an ammonia cracking reactor;
cracking the ammonia in the ammonia stream in the one or more catalyst containing reaction tubes disposed within the ammonia cracking reactor to produce a hydrogen containing stream;
feeding the hydrogen containing stream to a purification unit and increasing the H 2 content of the hydrogen containing stream to produce an enriched hydrogen stream and a tail gas; and
supplying a hydrogen containing recycle gas taken from downstream of the ammonia cracking reactor to the one or more catalyst containing reaction tubes disposed within the ammonia cracking reactor, wherein the hydrogen containing recycle gas comprises a portion of the enriched hydrogen containing stream.