GB669919A - Improvements in or relating to apparatus for heat treating solid materials - Google Patents

Abstract

669,919. Shaft furnaces. WEDGEWOOD & SONS, Ltd., J., and WEDGEWOOD, C. T. May 25, 1950 [May 25, 1949], No. 13983/49. Class 51 (ii). Apparatus for calcining flint or heat treating other solid materials comprises a chamber through which the material travels in one direction, main gas inlet openings at the discharge end of the chamber, main gas outlet openings at the charging end of the chamber, subsidiary gas inlets and outlets at intermediate points and means for heating the material as, it passes through an intermediate zone in the chamber, including power-operated gas circulating apparatus for continually withdrawing preheated gas through the subsidiary outlets and returning it through the subsidiary inlets. As shown in Fig. 1, in a shaft kiln for calcining flint cool air enters at D, is withdrawn at G, passes through an electrical heating device H, is returned to the kiln at H<SP>2</SP> and is finally exhausted at F. In a modification the air withdrawn at G is partially or wholly burned with a liquid or gaseous fuel and the hot products of combustion returned to the kiln at H<SP>2</SP>. In a further modification air withdrawn at G is delivered to the inlet of a liquid or gaseous fuel burner which directs the burning mixture into the kiln at H<SP>2</SP>. In a still further modification electrical heating elements are provided within the kiln and air withdrawn from immediately above the heating elements is re-introduced below them. The kiln has a charging hopper B and a discharging container C.