Process for the separation of NH3 and CO2 from mixtures of NH.sub.2 and water

Claim 2

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, said process comprising the steps of: separating an ammonia off-gas substantially free of carbon dioxide and water by rectification in an ammonia separation zone, and removing the resulting residual liquid phase containing ammonia, carbon dioxide and water therefrom and introducing it into a carbon dioxide separation zone; separating a carbon dioxide off-gas substantially free of ammonia and water by rectification in a carbon dioxide separation zone and removing the resulting residual liquid phase containing ammonia, carbon dioxide and water therefrom and introducing it into a desorption zone; and separating an off-gas containing ammonia, carbon dioxide and water vapor from a liquid phase of desorption water substantially free of ammonia and carbon dioxide, and introducing at least a portion of said off-gas into said ammonia separation zone; the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 3

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia, said process comprising the steps of: introducing said mixture into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; and introducing at least a portion of said desorption zone off-gas into said ammonia separation zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the total weight of said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 4

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia, said process comprising the steps of: introducing said mixture into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; and introducing at least a portion of said desorption zone off-gas into said ammonia separation zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the total weight of said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 5

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is lean with respect to ammonia, said process comprising the steps of: introducing said mixture into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said ammonia separation zone into said carbon dioxide separation zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the combined total weight of said mixture and said residual liquid phase from said mixture and said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 6

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is lean with respect to ammonia, said process comprising the steps of: introducing said mixture into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said ammonia separation zone into said carbon dioxide separation zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the combined total weight of said mixture and said residual liquid phase from said mixture and said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 7

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia and additionally contains a substantial amount of water, said process comprising the steps of: introducing said mixture into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said carbon dioxide separation zone into said desorption zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the total weight of said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 8

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia and additionally contains a substantial amount of water, said process comprising the steps of: introducing said mixture into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said carbon dioxide separation zone into said desorption zone; wherein diluting water is introduced into said carbon dioxide separation zone in an amount of between about 0.2 and 6 times, by weight, the total weight of said residual liquid phase from said ammonia separation zone introduced into said carbon dioxide separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 9

The process of claims 2, 3 or 4 wherein the system pressure in said carbon dioxide separation zone is no greater than twice the system pressure in said ammonia separation zone.

Claim 10

The process of claim 5 wherein the system pressure in said carbon dioxide separation zone is substantially the same as the system pressure in said ammonia separation zone.

Claim 11

In an process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia, said process comprising the steps of: introducing said mixture into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; and introducing at least a portion of said desorption zone off-gas into said ammonia separation zone; wherein the system pressure in said carbon dioxide separation zone is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 12

In an process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia, said process comprising the steps of: introducing said mixture into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; and introducing at least a portion of said desorption zone off-gas into said ammonia separation zone; wherein the system pressure in said carbon dioxide separation zone is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 13

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is lean with respect to ammonia, said process comprising the steps of: introducing said mixture into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said ammonia separation zone into said carbon dioxide separation zone; wherein the system pressure in said carbon dioxide separation one is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 14

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is lean with respect to ammonia, said process comprising the steps of: introducing said mixture into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said carbon dioxide separation zone into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said ammonia separation zone into said carbon dioxide separation zone; wherein the system pressure in said carbon dioxide separation one is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 15

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia and additionally contains a substantial amount of water, said process comprising the steps of: introducing said mixture into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said carbon dioxide separation zone into said desorption zone; wherein the system pressure in said carbon dioxide separation zone is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 16

In a process for the separate recovery of ammonia substantially free of carbon dioxide and water, and carbon dioxide substantially free of ammonia and water, from a mixture essentially containing ammonia and carbon dioxide, which mixture is rich with respect to ammonia and additionally contains a substantial amount of water, said process comprising the steps of: introducing said mixture into a desorption zone and separately removing therefrom a desorption zone off-gas containing ammonia, carbon dioxide and water vapor, and a liquid phase of desorption water substantially free of ammonia and carbon dioxide; introducing at least a portion of said desorption zone off-gas into an ammonia separation zone and separately removing therefrom an ammonia off-gas substantially free of carbon dioxide and water, and a residual liquid phase containing ammonia, carbon dioxide and water; introducing said residual liquid phase from said ammonia separation zone into a carbon dioxide separation zone and separately removing therefrom a carbon dioxide off-gas substantially free of ammonia and water and a residual liquid phase containing ammonia, carbon dioxide and water; and introducing said residual liquid phase from said carbon dioxide separation zone into said desorption zone; wherein the system pressure in said carbon dioxide separation zone is greater than twice the system pressure in said ammonia separation zone, the improvement comprising introducing into the portion of said carbon dioxide separation zone from which said residual liquid phase is removed, an ammonia containing gaseous phase in an amount sufficient to make said residual liquid phase removed therefrom lean with respect to carbon dioxide.

Claim 17

The process of claim 7, 8 or 9 wherein the ratio between the respective system pressures in said ammonia separation zone and in said carbon dioxide separation zone is between about 1:5 and 1:20.

Claim 18

The process of claim 7, 8 or 9 wherein diluting water is introduced into said carbon dioxide separation zone.

Claim 19

The process of claim 1, 2, 3, 4, 7, 8 or 9 wherein said ammonia containing gaseous phase introduced into said carbon dioxide separation zone is comprised of a portion of said desorption zone off-gas.

Claim 20

The process of claim 12 wherein from about 1 to 50% by weight of said off-gas removed from said desorption zone is utilized as said ammonia containing gaseous phase.

Claim 21

The process of claim 12 wherein from about 5 to 40% by weight of said off-gas removed from said desorption zone is utilized as said ammonia containing gaseous phase.