Basf Aktiengesellschaft

Hermann Dieter Fromm

Hans Henning Schneehage

Hans Gettert

Ernst-Juergen Schier

Alfred Widmann

Engelbert Hillenbrand

Martin Molzahn

Melamine synthesis waste gases are first treated for the removal of melamine by condensation. The waste gases are then treated with urea-containing melts which are cooled indirectly. At least parts of said indirect cooling takes place together with the treatment of the reaction waste gases with the urea-containing melts in a single zone.

Process for cooling melamine synthesis waste gases

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.

Isolation of pure ammonia from gas mixtures containing ammonia and

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Gruenstadt, Germany

Hermann Dieter Fromm