Isolation of pure ammonia from gas mixtures containing ammonia and carbon dioxide
First Claim
1. A process for isolating ammonia from gas mixtures containing ammonia and carbon dioxide by partially absorbing the gas mixture in a solvent, with intimate mixing and using residence times of at most 0.1 second, then separating the non-absorbed gas mixture and the solution obtained, and desorbing the solution containing excess ammonia, wherein, in a first desorption stage, only the ammonia present in an excess over a molar ratio of 3 parts of ammonia to 1 part of carbon dioxide is expelled by heating and the entrained carbon dioxide is washed out of the expelled ammonia with solutions which contain free ammonia, the residual solution from the first desorption stage is substantially freed from ammonia and carbon dioxide in a second desorption stage, the expelled solvent-containing gas together with fresh gas mixture is recycled to the absorption and the solvent obtained from the second desorption stage is employed as solvent in the absorption.
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Abstract
To isolate ammonia from gas mixtures containing ammonia and carbon dioxide, the gas mixture is first partially absorbed in a solvent, with residence times of at most 0.1 second, and the non-absorbed gas is then separated from the solution obtained. The solution is then subjected to a first desorption stage, in which only the ammonia present in an excess over a molar ratio of 3 parts of ammonia to 1 part of carbon dioxide is expelled by heating, and the entrained carbon dioxide is washed out of the expelled ammonia by means of solutions containing free ammonia. The solution remaining after the first desorption stage is substantially freed from ammonia and carbon dioxide in a second desorption stage and the expelled gas, containing solvent, together with fresh gas mixture is fed to the adsorption stage, while the solvent obtained from the second desorption stage is employed for the absorption.
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Citations
10 Claims
- 1. A process for isolating ammonia from gas mixtures containing ammonia and carbon dioxide by partially absorbing the gas mixture in a solvent, with intimate mixing and using residence times of at most 0.1 second, then separating the non-absorbed gas mixture and the solution obtained, and desorbing the solution containing excess ammonia, wherein, in a first desorption stage, only the ammonia present in an excess over a molar ratio of 3 parts of ammonia to 1 part of carbon dioxide is expelled by heating and the entrained carbon dioxide is washed out of the expelled ammonia with solutions which contain free ammonia, the residual solution from the first desorption stage is substantially freed from ammonia and carbon dioxide in a second desorption stage, the expelled solvent-containing gas together with fresh gas mixture is recycled to the absorption and the solvent obtained from the second desorption stage is employed as solvent in the absorption.
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