Patent ID: 8349090

Claim:
A process for removing a carbonaceous deposit on a surface of at least one of a catalyst and a plant part, the process comprising the steps of: (a) treating the carbonaceous deposit with superheated steam, without a supply of oxygen, at a temperature of at least 300° C. to generate a reaction comprising an offgas, wherein the treating step is performed until a CO 2 content in the offgas has exceeded a maximum value; (b) then, with further supply of superheated steam, commencing a supply of an oxygen-comprising gas, wherein an amount of oxygen supplied is adjusted such that the CO 2 content in the offgas decreases further until it has fallen to a value of <1% by volume; and then (c) reducing until ending the supply of superheated steam, while passing the oxygen-comprising gas over amounts of the carbonaceous deposit still remaining until the carbonaceous deposit has been virtually removed, wherein the maximum value of the CO 2 content in the offgas is based on gasifying the carbonaceous deposit.