Synthesis gas for ammonia production

Claim 2

A process for producing a feed gas stream for the synthesis of ammonia which comprises: (a) partially oxidising a substance selected from the group consisting of oil, coal, natural gas or any combination thereof in the presence of air at a pressure of 15 to 150 bar and at a temperature of 300° to 2000° C. to produce a raw gas stream containing hydrogen and nitrogen with a stoichiometric excess of nitrogen of at least 200 mole percent based upon that needed for ammonia synthesis, together with carbon oxides, methane and hydrogen sulphide if sulphur was present in the oil, coal or gas, (b) treating the raw gas stream from step (a) to remove substantially all component gases other than hydrogen and nitrogen, (c) drying the raw gas stream from step (b) if water is present, (d) subjecting the raw gas stream from step (c) at a pressure of 15 to 100 bar to a separation stage to separate (1) a hydrogen-nitrogen feed gas stream at a pressure of 15 to 100 bar, said feed gas stream having a predetermined nitrogen:hydrogen ratio suitable for ammonia synthesis, and (2) a nitrogen-rich gas stream at a pressure of 5 to 50 bar, (e) injecting said hydrogen-nitrogen feed gas stream from step (d) into a reactor for ammonia synthesis, (f) heating said nitrogen-rich gas stream from step (d), still at a pressure of 5 to 50 bar, to a temperature of 500° to 2000° C., and (g) expanding said high pressure nitrogen-rich gas stream from step (f) in a turbine to generate power.

Claim 3

A process according to claim 1 wherein the separation stage in step (d) is performed in a cryogenic separator.

Claim 4

A process according to claim 2 wherein said raw gas stream resulting from the partial oxidation is passed over a shift catalyst and reacted with steam at elevated temperature to convert the carbon monoxide present in said raw gas stream to carbon dioxide and hydrogen.

Claim 5

A process according to claim 3 wherein said raw gas stream, after passing over the shift catalyst, is subjected to scrubbing with hot potassium carbonate at a temperature of 70 to 110 degrees C. to remove the acid gas content prior to the separation stage.

Claim 6

A process according to claim 4 wherein said raw gas stream, after scrubbing with hot potassium carbonate, is subjected to liquid nitrogen washing to remove carbon monoxide in said raw gas stream prior to the separation stage.

Claim 7

A process according to claim 5 wherein the separation stage is conducted in a cryogenic separator and the liquid nitrogen in the washing step is obtained from the nitrogen condensed in the cryogenic separator.

Claim 8

A process according to claim 4 wherein said raw gas stream after scrubbing with hot potassium carbonate is subjected to methanation to remove any carbon oxides prior to the separation stage.

Claim 9

A process according to claim 1 wherein said nitrogen-rich stream is mixed with supplementary fuel and fed to the combustion chamber of a gas turbine as fuel.

Claim 10

A process according to claim 8 wherein said process air requirement for the partial oxidation is bled from the gas turbine compressor discharge.

Claim 11

A process according to claim 1 wherein said stoichiometric excess of nitrogen is from 230 to 270 mole percent based upon that needed for ammonia synthesis.

Claim 12

A process for producing a feed gas stream for the synthesis of ammonia which comprises: (a) partially oxidising a substance selected from the group consisting of oil, coal, natural gas, or any combination thereof in the presence of air at a pressure of 15 to 150 bar and at a temperature of 300° to 2000° C. to produce a raw gas stream containing hydrogen and nitrogen with a stoichiometric excess of nitrogen of at least 200 mole percent based upon that needed for ammonia synthesis, together with carbon oxides, methane and hydrogen sulphide if sulphur was present in the oil, coal, or gas; (b) passing said raw gas stream from step (a) over a shift catalyst and reacting said raw gas stream with steam at elevated temperature to convert the carbonl monoxide present to carbon dioxide and hydrogen; (c) treating said raw gas stream from step (b) to remove carbon dioxide in a wash solution; (d) treating the raw gas stream from step (c) to remove substantially all component gases other than hydrogen and nitrogen; (e) drying the raw gas stream from step (d) if water is present; (f) subjecting the raw gas stream from step (e) at a pressure of 15 to 100 bar to a cryogenic separation stage to separate (1) a hydrogen-nitrogen feed gas stream at a pressure of 15 to 100 bar, said feed gas stream having a predetermined nitrogen:hydrogen ratio suitable for ammonia synthesis, and (2) a nitrogen-rich gas stream at a pressure of 5 to 50 bar; (g) injecting said hydrogen-nitrogen feed gas stream from step (f) into a reactor for ammonia synthesis; (h) using said nitrogen-rich gas stream produced by the cryogenic separator in step (f), still at a pressure of 5 to 50 bar, to strip a substantial part of the carbon dioxide from the wash solution produced in step (c); (i) heating the combined nitrogen and carbon dioxide stream from step (h), still at a pressure of 5 to 50 bar, to a temperature of 500° to 2000° C.; and, (j) expanding said combined nitrogen and carbon dioxide stream from step (i) in a turbine to generate power.

Claim 13

A process for producing a feed gas stream for the synthesis of ammonia which comprises: (a) partially oxidising a substance selected from the group consisting of oil, coal, natural gas, or any combination thereof in the presence of air at a pressure of 15 to 150 bar and at a temperature of 300° to 2000° C. to produce a raw gas stream containing hydrogen and nitrogen with a stoichiometric excess of nitrogen of at least 200 mole percent based upon that needed for ammonia synthesis, together with carbon oxides, methane and hydrogen sulphide if sulphur was present in the oil, coal, or gas; (b) passing said raw gas stream from step (a) over a shift catalyst and reacting said raw gas stream with steam at elevated temperature to convert the carbonl monoxide present to carbon dioxide and hydrogen; (c) treating said raw gas stream from step (b) to remove carbon dioxide in a wash solution; (d) treating the raw gas stream from step (c) to remove substantially all component gases other than hydrogen and nitrogen; (e) drying the raw gas stream from step (d) if water is present; (f) subjecting the raw gas stream from step (e) at a pressure of 15 to 100 bar to a cryogenic separation stage to separate (1) a hydrogen-nitrogen feed gas stream at a pressure of 15 to 100 bar, said feed gas stream having a predetermined nitrogen:hydrogen ratio suitable for ammonia synthesis, and (2) a nitrogen-rich gas stream at a pressure of 5 to 50 bar; (g) injecting said hydrogen-nitrogen feed gas stream from step (f) into a reactor for ammonia synthesis; (h) using said nitrogen-rich gas stream produced by the cryogenic separator in step (f), still at a pressure of 5 to 50 bar, to strip a substantial part of the carbon dioxide from the wash solution produced in step (c); (i) heating the combined nitrogen and carbon dioxide stream from step (h), still at a pressure of 5 to 50 bar, to a temperature of 500° to 2000° C.; and, (j) expanding said combined nitrogen and carbon dioxide stream from step (i) in a turbine to generate power.