Patent ID: 7895769

Claim:
A method for thermally drying wet-ground cement raw meal in the form of a pumpable sludge, which sludge is introduced into a cyclone suspension type heat exchanger system of a cement clinker production line working according to the dry method, with a dryer, with utilization of heat contained in gaseous flows of the cyclone suspension type heat exchanger system and with separation of dried meal from exhaust vapors formed during drying, comprising the steps: a) introducing the pumpable raw meal sludge, as well as an exhaust vapor flow being re-circulated in the dryer as an exhaust vapor recirculation flow in a steam circuit, in a lower part of the dryer constructed as a vapor flow dryer, b) heating the recirculated exhaust vapor flow prior to its introduction into the lower part of the dryer by indirect heat transmission from gaseous flows from the cyclone suspension type heat exchanger system, c) removing a partial vapor flow, which corresponds to water evaporated during raw meal sludge drying, from the steam circuit, by extraction in the form of a condensate, after first increasing the vapor temperature of the partial vapor flow with a vapor compressor and then by passing vapor from the vapor recirculation flow in the dryer over a heating surface of a vapor condenser.