Process and plant for the combined production of an ammonia synthesis mixture and carbon monoxide
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsJean Billy, Daniele Fauroux
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Abstract
In the process of the invention, an ammonia synthesis mixture and carbon monoxide are produced. The hydrogen is purified in a nitrogen-washing column (61). The carbon monoxide is recovered cryogenically from a first liquid fraction (51) collected at the base of the said washing column (61), in a medium-pressure stripping column (62), then in a low-pressure distillation column (63). A second liquid fraction (52) is drawn from a position intermediate between the base and head of the washing column (61).
Claims18
In a process for combined production of an ammonia synthesis mixture and carbon monoxide, comprising the production of an ammonia synthesis mixture (N2+3H2) from a) hydrogen under high pressure, purified in a final step by washing with nitrogen in a washing column, and b) a stream of nitrogen at high pressure, the improvement which comprises:
- drawing off a first liquid fraction from the base of the nitrogen-washing column which is rich in carbon monoxide and lean in residual constituents including nitrogen, hydrogen and methane;
- and a second liquid fraction at an intermediate position between the base and head of the washing column, which is rich in nitrogen and lean in carbon monoxide;
- cryogenically purifying, the carbon monoxide from the first liquid fraction by a first separation under medium pressure in a stripping column separating the residual hydrogen at the head, and a second distillation under low pressure in a distillation column separating the carbon monoxide and the residual nitrogen at the head from the base mixture resulting from the first separation in the stripping column.
In a plant for the combined production of an ammonia synthesis mixture and carbon monoxide comprising cryogenic means for separating the constituents of a gas mixture containing essentially hydrogen and carbon monoxide, as well as other constituents including nitrogen and methane, including a heat exchanger, a source capable of providing a stream of nitrogen at high pressure and a column for washing with liquid nitrogen, the improvement wherein:
- the nitrogen-washing column comprises means for drawing off liquid from a position intermediate between the base and the head of the column, and
- the plant further comprises
- a medium-pressure stripping column provided with boiling means, producing a liquid fraction rich in carbon monoxide at the base, and hydrogen at the head;
- a line provided with expansion means for conveying the base liquid fraction from the nitrogen-washing column to the stripping column;
- a low-pressure distillation column provided with boiling means and with a head condenser, producing a fraction rich in methane at the base and a fraction rich in carbon monoxide at the head;
- and
- a line provided with expansion means for conveying the base liquid fraction from the stripping column to an intermediate position on the distillation column.
In a plant for combined production of an ammonia synthesis mixture and carbon monoxide, comprising the production of an ammonia synthesis mixture (N2+3H2) from a) a source of hydrogen under high pressure, purified in a final step by washing with nitrogen in a washing column, and b) a stream of nitrogen at high pressure;
- the improvement, wherein the plant further comprises:
- means for drawing off a first liquid fraction from the base of the nitrogen-washing column which is rich in carbon monoxide and lean in residual constituents including nitrogen, hydrogen and methane;
- and a second liquid fraction at an intermediate position between the base and head of the washing column, which is rich in nitrogen and lean in carbon monoxide;
- and
- means for cryogenically purifying the carbon monoxide from the first liquid fraction by a first separation under medium pressure in a stripping column separating the residual hydrogen at the head, and a second distillation under low pressure in a distillation column separating the carbon monoxide and the residual nitrogen at the head from the base mixture resulting from the first separation in the stripping column.
Dependencies are inferred from the claim text.