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摘要

A method of removing deposits containing oxalate that are difficult to dissolve, from the heating surfaces of a heat exchanger in an evaporation apparatus, having a vessel in which the heat exchanger is arranged. In accordance with the invention the following steps are performed: (a) stopping the evaporation process for evaporating spent liquor containing oxalate and emptying the vessel of its spent liquor contents; (b) rinsing the heating surfaces clean from residue of spent liquor with water and emptying the vessel of its contents of this mixture; (c) supplying heat to the vessel to raise the temperature therein to a predetermined minimum value; (d) causing gas to flow through the vessel to remove moisture therefrom until a dry environment is obtained so that the deposits become dry and assume said minumum temperature, whereby the deposits fracture into brittle particle structures; (e) discontinuing step (c) and step (d) and causing liquid to circulate through the vessel to remove the particles from the heating surfaces; and (f) drawing off the mixture of liquid and particles from the vessel.