Process for preparing dialkyl carbonates

A process for preparing dialkyl carbonate from cyclic alkylene carbonate and alkyl alcohol in at least one transesterification column and at least one subsequent distillation column for purifying the dialkyl carbonate formed in the transesterification column, wherein the transesterification column comprises at least one reaction zone and at least one enrichment section arranged above the reaction zone, and wherein the column comprises at least one enrichment section in the upper part of the column and at least one stripping section in the lower part of the column, wherein the process comprises

• heating a liquid stream in the at least one transesterification column and/or vaporizing, entirely or partly, a dialkyl carbonate-containing alkyl alcohol stream fed to the at least one transesterification column with a technical device,
• wherein a temperature TI of a medium for heating the internal liquid stream in the column and/or for vaporizing an introduced dialkyl carbonate-containing alkyl alcohol stream is less than a temperature TBV of a medium used in a bottom vaporizer,
• recovering, partly or entirely, the energy of the medium for heating the internal liquid stream in the column and/or for vaporizing an introduced dialkyl carbonate-containing alkyl alcohol stream in another chemical production process, and
• where, with the proviso that the liquid stream is heated in the transesterification column, the technical device for heating the liquid stream is arranged above a bottom vaporizer of the at least one transesterification column.