Abstract: A heat exchanger consisting of a housing (1) with integrated caloric surfaces (3) for cooling bulk materials (8)--in particular hot foundry molding sands--comprises a retarder system in the form of a sand cascade which consists of an upper perforated plate (9) with many small individual holes (11), of a lower perforated plate (12) with few individual holes (12), said perforated plates being spaced apart by perforated plates (4,15), the sand flow through the slide system (5,6,14) being controllable and sealable.The passage holes may assume the shapes of triangular, longitudinal or T slots in order to operate such a retarder cooler over a large range of regulation.The perforated spacer plates (4) moreover form a support plate with high static load capacities to absorb the substantial weights of the bulk materials.

Abstract: A burner (1,29) for the combustion of powdery fuels, in particular coal-dust, comprises a central duct (9,37) to supply a jet of core-air (13,41), a fuel channel (12,40) to supply the fuel and a casing channel (5,6; 31) to supply secondary air (7,8; 36).In order to make such a burner (1,29) also suitable for lesser power ranges, a widened range of regulation and less sensitive to a wide coal-dust band, the discharge means of the fuel channel (12,40) is designed as an annular nozzle (23,53) of which at least one of the two circumferential walls (19,47) is rotatable and driven, and the discharge means of the central duct (13,41) being so designed that the jet of core-air (13,41) is directed at least in part outwardly against the discharging fuel for the purpose of deflection into the region of the secondary air (7,8; 36).

Abstract: A system is provided for cooling high-temperature, high-pressure gasifiers having cooling tubes which extend vertically through the walls of the gasifier and are connected in a closed cooling water circulation system.In accordance with the invention, the cooling tubes are coated on the inside of the gasifier with a plasma or flame sprayed ceramic coating, preferably consisting of alumina, and are embedded in a ramming compound such as tamped clay.

Abstract: A system for cooling high-temperature gasifiers and method for its operation wherein cooling conduits extend vertically through the walls of the gasifier and are connected at their ends to a closed-water circulation system which incorporates heat exchangers for removing heat from the system. Boiling in the system is prevented, and good heat transfer characteristics are achieved, by maintaining a high pressure system, at least 40 bar, coupled with a flow velocity of between 5 and 7 meters per second at a maximum internal diameter of the cooling conduits of 51 millimeters. Means are provided for maintaining the temperature of the water exiting from the cooling conduits at least 10.degree. C below the boiling point at the pressure and flow rate of the system.