US 5,223,238 AGranted

Method for treating ammonia and urea condensates

AssigneeThe M. W. Kellogg Company

InventorThomas A. Czuppon

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Abstract

A method is described which enables ammonia plant process condensate contaminated with ammonia, carbon dioxide and methanol and urea plant condensate contaminated with urea, ammonia, carbon dioxide and other combined forms of ammonia and carbon dioxide to be simultaneously converted, in a single treatment vessel, substantially and continuously to a vaporous stream rich in ammonia, carbon dioxide and methanol and an liquid stream poor in ammonia, carbon dioxide, methanol and urea. The vaporous stream thus produced is recycled and employed as a feedstock in the reforming section in the ammonia plant.

Claims9

Dependent claims

In a process for manufacturing both ammonia and urea wherein first and second process condensates are produced, a continuous method for concurrently treating said process condensates in a single, vertically positioned treatment vessel having an upper hydrolysis zone and a lower stripping zone comprising the steps of:

(a) preheating the first process condensate comprising a dilute aqueous stream consisting essentially of ammonia, carbon dioxide and methanol and introducing said preheated first condensate into an upper end of the lower stripping zone of the single treatment vessel;
(b) blending the preheated first condensate within the upper end of the stripping zone with a first liquid stream produced in and recovered from the upper hydrolysis zone of the single treatment vessel;
(c) contacting the blended stream, within the stripping zone, in a countercurrent flow relationship with steam introduced into a lower end of the stripping zone, said contact being carried out at a temperature and pressure effective to remove a substantial portion of the ammonia, carbon dioxide and methanol from said blended stream and thereby produce an aqueous vaporous stream rich in said ammonia, carbon dioxide and methanol and a second liquid stream substantially free of said ammonia, carbon dioxide and methanol;
(d) withdrawing the vaporous stream from the upper end of the stripping zone and introducing the vaporous stream into a lower end of the upper hydrolysis zone of the single treatment vessel;
(e) preheating the second process condensate comprising a dilute aqueous stream consisting essentially of water, urea, ammonia and carbon dioxide and introducing said preheated second condensate into an upper end of the hydrolysis zone of the single treatment vessel;
(f) contacting the preheated second condensate, within the hydrolysis zone, in a countercurrent flow relationship with the vaporous stream produced in and withdrawn from the lower stripping zone, said contact being carried out at a temperature and pressure effective to hydrolyze the urea contained in the preheated second condensate to ammonia and carbon dioxide and thereby produce the first liquid stream rich in said ammonia and carbon dioxide;
(g) withdrawing said vaporous stream from said hydrolysis zone and the second stream from said stripping zone.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/821,209Filed 16 Jan 1992
Granted: 29 Jun 1993
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

C01C 1/0488
From N2 and H2 in presence of a catalyst: processes integrated with preparations of other compounds, e.g. methanol, urea or with processes for…
C01B 3/025
Production of hydrogen; Production of gaseous mixtures containing hydrogen: preparation or purification of gas mixtures for ammonia synthesis
C01C 1/10
Preparation, purification or separation of ammonia: separation of ammonia from ammonia liquors, e.g. gas liquors
C07C 273/10
Of urea, its salts, complexes or addition compounds: combined with the synthesis of ammonia

Family

No related US applications are recorded in the indexed filing history.

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Abstract

(a) preheating the first process condensate comprising a dilute aqueous stream consisting essentially of ammonia, carbon dioxide and methanol and introducing said preheated first condensate into an upper end of the lower stripping zone of the single treatment vessel;
(b) blending the preheated first condensate within the upper end of the stripping zone with a first liquid stream produced in and recovered from the upper hydrolysis zone of the single treatment vessel;
(c) contacting the blended stream, within the stripping zone, in a countercurrent flow relationship with steam introduced into a lower end of the stripping zone, said contact being carried out at a temperature and pressure effective to remove a substantial portion of the ammonia, carbon dioxide and methanol from said blended stream and thereby produce an aqueous vaporous stream rich in said ammonia, carbon dioxide and methanol and a second liquid stream substantially free of said ammonia, carbon dioxide and methanol;
(d) withdrawing the vaporous stream from the upper end of the stripping zone and introducing the vaporous stream into a lower end of the upper hydrolysis zone of the single treatment vessel;
(e) preheating the second process condensate comprising a dilute aqueous stream consisting essentially of water, urea, ammonia and carbon dioxide and introducing said preheated second condensate into an upper end of the hydrolysis zone of the single treatment vessel;
(f) contacting the preheated second condensate, within the hydrolysis zone, in a countercurrent flow relationship with the vaporous stream produced in and withdrawn from the lower stripping zone, said contact being carried out at a temperature and pressure effective to hydrolyze the urea contained in the preheated second condensate to ammonia and carbon dioxide and thereby produce the first liquid stream rich in said ammonia and carbon dioxide;
(g) withdrawing said vaporous stream from said hydrolysis zone and the second stream from said stripping zone.

4 more elements

Facts

Application

07/821,209Filed 16 Jan 1992

Granted

29 Jun 1993

Term ends

Not estimatedThe source records don’t support an estimate.

Classification9 codes

C01C 1/0488
From N2 and H2 in presence of a catalyst: processes integrated with preparations of other compounds, e.g. methanol, urea or with processes for…
C01B 3/025
Production of hydrogen; Production of gaseous mixtures containing hydrogen: preparation or purification of gas mixtures for ammonia synthesis
C01C 1/10
Preparation, purification or separation of ammonia: separation of ammonia from ammonia liquors, e.g. gas liquors
C07C 273/10
Of urea, its salts, complexes or addition compounds: combined with the synthesis of ammonia