Low energy ammonia synthesis process

Claim 2

In a process for the production of ammonia which comprises a series of process steps including producing a raw synthesis gas and converting the carbon monoxide in said raw synthesis gas to carbon dioxide for producing a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio, the improvement which comprises: reacting said hydrogen and nitrogen in an ammonia synthesis converter at pressures less than 100 atmospheres to produce an effluent containing ammonia; scrubbing said effluent with water to form a water-ammonia mixture; distilling ammonia from said water-ammonia mixture by means of a distillation column heated by removing liquid therefrom at several levels; and passing in indirect heat exchange with said liquid the effluent from one of said process steps.

Claim 3

A process according to claim 1 wherein said synthesis pressure is within the range of 20 to 70 atmospheres.

Claim 4

A process according to claim 1 wherein one of said process steps is a shift conversion process and the effluent from said process provides heat for distilling said water-ammonia mixture.

Claim 5

A process according to claim 3 wherein said synthesis pressure is within the range of 25 to 50 atmospheres.

Claim 6

A process according to claim 1 wherein the unabsorbed gases in the ammonia synthesis converter effluent after scrubbing are recycled to said ammonia synthesis converter.

Claim 7

In a process for the production of ammonia, comprising the steps of: (a) producing a raw synthesis gas which contains hydrogen and carbon monoxide; (b) converting the carbon monoxide in said raw synthesis gas to carbon dioxide and further hydrogen by the addition of steam; (c) scrubbing the gas to remove the carbon dioxide; and (d) purifying said scrubbed gas to produce a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises reacting said hydrogen and nitrogen in an ammonia synthesis converter at pressures less than 100 atmospheres to produce an effluent containing ammonia; scrubbing said effluent with water to form a water-ammonia mixture; distilling ammonia from said water-ammonia mixture by means of a distillation column heated by removing liquid therefrom at several levels; and passing in indirect heat exchange with said liquid the effluent from step (b).

Claim 8

In a process for the production of ammonia, comprising the steps of: (a) producing a raw synthesis gas which contains hydrogen and carbon monoxide; (b) converting the carbon monoxide in said raw synthesis gas to carbon dioxide and further hydrogen by the addition of steam; (c) scrubbing the gas to remove the carbon dioxide; and (d) purifying said scrubbed gas to produce a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises reacting said hydrogen and nitrogen in an ammonia synthesis converter at pressures less than 100 atmospheres to produce an effluent containing ammonia; scrubbing said effluent with water to form a water-ammonia mixture; distilling ammonia from said water-ammonia mixture by means of a distillation column heated by removing liquid therefrom at several levels; and passing in indirect heat exchange with said liquid the effluent from step (b).

Claim 9

A process according to claim 6 wherein said synthesis pressure is within the range of 20 to 70 atmospheres.

Claim 10

A process according to claim 6 wherein the step of producing a raw synthesis gas is accomplished by primary steam reforming and secondary steam reforming.

Claim 11

A process according to claim 8 wherein said synthesis pressure is within the range of 25 to 30 atmospheres.

Claim 12

A process according to claim 8 wherein the pressure in said steam reforming and said synthesis pressures is within the range of 25 to 50 atmospheres.

Claim 13

In a process for the production of ammonia, comprising the steps of: (a) producing a hydrogen-rich gas by the primary steam reforming of a hydrocarbon; (b) producing a raw synthesis gas by the secondary steam reforming of said hydrogen-rich gas; (c) converting the carbon monoxide in said reformed gas to carbon dioxide and further hydrogen by the addition of steam; (d) scrubbing the gas to remove the carbon dioxide and (e) purifying said scrubbed gas to produce a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises reacting said hydrogen and nitrogen in an ammonia synthesis converter at pressures less than 100 atmospheres to produce an effluent containing ammonia; scrubbing said effluent with water to form a water-ammonia mixture; distilling ammonia from said water-ammonia mixture by means of a distillation column heated by removing liquid therefrom at several levels; and passing in indirect heat exchange with said liquid the effluent from step (c).

Claim 14

In a process for the production of ammonia, comprising the steps of: (a) producing a hydrogen-rich gas by the primary steam reforming of a hydrocarbon; (b) producing a raw synthesis gas by the secondary steam reforming of said hydrogen-rich gas; (c) converting the carbon monoxide in said reformed gas to carbon dioxide and further hydrogen by the addition of steam; (d) scrubbing the gas to remove the carbon dioxide and (e) purifying said scrubbed gas to produce a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises reacting said hydrogen and nitrogen in an ammonia synthesis converter at pressures less than 100 atmospheres to produce an effluent containing ammonia; scrubbing said effluent with water to form a water-ammonia mixture; distilling ammonia from said water-ammonia mixture by means of a distillation column heated by removing liquid therefrom at several levels; and passing in indirect heat exchange with said liquid the effluent from step (c).

Claim 15

A process according to claim 11 wherein the pressure of the effluent from step (a) and said synthesis pressure is within the range of about 33 to 41 atmospheres.

Claim 16

A low energy ammonia synthesis loop which comprises means for the synthesis of ammonia from a synthesis gas at low pressures; means for scrubbing the effluent of the synthesis means with water to form a water-ammonia mixture; a distillation column for distilling the water-ammonia mixture having a plurality of side reboilers for heating the water-ammonia mixture from said distillation column; and means for passing in indirect heat exchange with the water-ammonia mixture in said side reboilers the effluent of the shift conversion process used in preparing said synthesis gas to distill the ammonia from the water-ammonia mixture.

Claim 17

A low energy ammonia synthesis loop which comprises means for the synthesis of ammonia from a synthesis gas at low pressures; means for scrubbing the effluent of the synthesis means with water to form a water-ammonia mixture; a distillation column for distilling the water-ammonia mixture having a plurality of side reboilers for heating the water-ammonia mixture from said distillation column; and means for passing in indirect heat exchange with the water-ammonia mixture in said side reboilers the effluent of the shift conversion process used in preparing said synthesis gas to distill the ammonia from the water-ammonia mixture.

Claim 18

A low energy ammonia synthesis loop for an ammonia plant which comprises (a) means for producing a raw synthesis gas which contains hydrogen and carbon monoxide; (b) shift conversion means for converting the carbon monoxide in said raw synthesis gas to carbon dioxide and further hydrogen by the addition of steam; (c) scrubbing means for removing the carbon dioxide from the gas; and (d) purifying means for producing a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises an ammonia synthesis converter for reacting said hydrogen and nitrogen at low pressures to produce an effluent containing ammonia; scrubbing means for scrubbing said effluent with water to form a water-ammonia mixture; a distillation column having a plurality of side reboilers wherein the water-ammonia mixture is heated for recovering ammonia from said water-ammonia mixture; and means for passing in indirect heat exchange with the water-ammonia mixture in said side reboilers the effluent from said shift conversion means.

Claim 19

A low energy ammonia synthesis loop for an ammonia plant which comprises (a) means for producing a raw synthesis gas which contains hydrogen and carbon monoxide; (b) shift conversion means for converting the carbon monoxide in said raw synthesis gas to carbon dioxide and further hydrogen by the addition of steam; (c) scrubbing means for removing the carbon dioxide from the gas; and (d) purifying means for producing a synthesis gas containing a mixture of hydrogen and nitrogen in approximately a 3 to 1 ratio the improvement which comprises an ammonia synthesis converter for reacting said hydrogen and nitrogen at low pressures to produce an effluent containing ammonia; scrubbing means for scrubbing said effluent with water to form a water-ammonia mixture; a distillation column having a plurality of side reboilers wherein the water-ammonia mixture is heated for recovering ammonia from said water-ammonia mixture; and means for passing in indirect heat exchange with the water-ammonia mixture in said side reboilers the effluent from said shift conversion means.

Claim 20

A synthesis loop according to claim 14 wherein said scrubbing means for scrubbing said effluent with water is a wetted wall absorber.