Linde Aktiengesellschaft

Ulrich Schrader

Gerhard Ranke

Gerhard Alzner

In a process for cleaning, cleaning a packed column utilized in a gas scrubbing operation wherein the packing is obstructed by solids formed during the scrubbing step, the obstructions are removed in a maximally economical fashion and without interrupting of normal operation. The packed column contains at least n, wherein n&gt;1, superimposed packed beds spatially separated from one another. During cleaning, the lowermost up to maximally the (n-1)th packed bed are flooded with scrubbing agent. Preferably, the packed column is used for scrubbing H.sub.2 S out of a feedgas mixture with an oxidative scrubbing agent wherein sulfur is formed during the scrubbing operation and deposited in the packed beds.

Process for the cleaning of a packed column

The combined production of ammonia and urea by the reaction of gases containing hydrocarbons with steam is conducted by using a steam reformer, downstream secondary reformer, and shift converter. The ammonia synthesis gas (hydrogen, nitrogen and carbon dioxide) is subjected to a high pressure scrubbing step with a physical solvent, to remove the acid impurities, especially CO.sub.2. The pressure on the loaded solvent is reduced to a first intermediate pressure for degasing of the coabsorbed inerts and then to a second intermediate pressure for removal of the bulk of the absorbed CO.sub.2, which is then used for urea synthesis. To remove residual CO.sub.2, the solvent is stripped with air and the resultant air stream containing the stripped residual CO.sub.2 is fed to the secondary reformer.

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Munich, Germany

Ulrich Schrader