GB181811A - Improvements in or relating to cement manufacture - Google Patents

Abstract

181,811. Merz & McLellan, and Weeks, E. G. March 17, 1921. Generating by indirect contact of heated gases. -In a plant for the manufacture of cement, the waste gases from the rotary kiln 10 are utilized in a low-pressure boiler 19, the steam from which is passed to an independently-fired superheater 28, and thence to a continuously operating low temperature distillation retort 13 having a fuel preheater 14. The gas from the retort is passed through a condenser 21, acting as a feedwater heater for the boiler, a cooler 24 and by-product recovery plant 26, and may then be used for firing the superheater 28 and for supplying additional heat to the boiler 19 when required. The solid residue from the retort is pulverized while still hot and is fed to the kiln by the fan 18. When additional fuel is required for the kiln the powdered residue, with or without other powdered raw fuel, is mixed with the residual oils front the gas, and fed to the kiln in colloid form. The waste gases from the kiln may be by-passed. round the boiler through the flue 34. The steam pipe 32 leading from the retort is jacketed by a flue 33, through which waste gases from the chimney 20 are passed to a jacket around the retort and thence to the preheater 14. In a modified form of apparatus the boiler and superheater are independently fired and the waste gases of the kiln are utilized for heating the feedwater only. The hot gas from the retort is passed through three heat interchanges in series which act respectively as a feedwater heater, a vaporizer and a superheater, and the steam from the last is passed to the superheater in connection with the main boiler.