644203-A is referenced by 2 patents.
644,203. Furnaces; distilling carbonaceous materials. DALIN, D., HEDBACK, T. J., GEJROT, C. J., and JOHANSSON, A. W. July 15, 1946, No. 21148. Convention date, July 17, 1945. [Classes 51(i) and 55(i)] In a retort furnace for the dry distillation of coal. wood, slate or like fuel in which the fuel residue is subsequently burnt externally of the retort to heat the retort, the temperature in the combustion zone is controlled by regulating the supply of combustion air and circulating a heatabsorbing medium through pipes or channels in the fuel layer. Cracking of the distillation gas and sintering of the fuel are thus avoided. In one form, Fig. 1, the furnace comprises a shaft 1 fitted with discharge rollers 6 for ash and enclosing two retorts 2.; The fuel is fed to a hopper 2a and passes down the retorts to the combustion zone 5, the flue gases passing upwardly around the retorts to a flue 3 and the distillation gases being sucked from the retorts through pipes 4 communicating with a main conduit 8. To prevent sintering of the fuel and cracking of the distillation gases, the shaft is fitted with a pipe system 10, similar to that described in Specification 641,541, through which a cooling medium such as water or steam is circulated. Some of the pipes project upwardly into the retorts, the bottoms of which are enclosed by cooling pipes 11 in the form of coils. Combustion air is supplied upwardly through the discharge rollers either by maintaining a sub-atmospheric pressure in the furnace shaft or a superatmospheric pressure in the ashpit.; To prevent mixing of the flue and distillation gases, a damper 12 operated by a servomotor 14 is fitted in the flue 3, the servomotor being controlled by a diaphragm 13 subjected on one side to the pressure in the shaft and on the other side to the pressure in the pipes 4 so that the two pressures are always balanced. A number of furnaces may be grouped together, see Fig. 2 (not shown), with a common main discharge passage for the distillation gas and a common control device for the gas pressures. The cooling pipes 10 may be fitted with jackets 10a of refractory material as shown in Fig. 3. Two pipes may be arranged in a single jacket. Flanges or ribs of refractory material may be provided on the cooling tubes and the interior and exterior of the retort walls, see Figs. 4 and 5 (not shown).; As shown in Fig. 6, the shaft 1 and retort 2 may be of rectangular cross-section, the retort enclosing a number of flues 26 and pipes 4 for distillation gases. In Fig. 9 (not shown), the shaft, retorts and pipes 4 are all of rectangular cross-section. As shown in Fig. 10, the lower ends of the pipes 4 may be fitted with heat-insulating jackets 31 and jackets 30 for the circulation of cooling medium.