Patent GB-228954-A (GB)
Title: Improvements in and relating to processes for the production of active carbon
IPC: C01B32/336
Filed: 1923-08-09
Abstract: 228,954. Sauer, J. N. A., and Algemeene Norit Maatschappij. Aug. 9, 1923. Addition to 198,328. Carbon and charcoal. - The invention comprises a number of improvements in the process of the parent Specification for preparing active carbon by subjecting a raw or precarbonized carbonaceous material to the action of heat and of activating gases in a rotary retort. One improvement consists in treating the material in suspension or in thin layers in a rotary retort mounted in a gas-tight casing. A second improvement consists in the provision of means, such as ribs, on the inner face of the retort to carry the material upwards and allow it to fall through the gases, while a further improvement is the provision of heat-radiating surfaces in the retort. A rotarv furnace 1 is mounted in a fixed casing 2, projects into inlet and outlet chambers 3, 4, and is rotated by gear wheels 23 carried by shafts passing through stuffing boxes, 26 and engaging toothed collars 24. The raw material, which may be fruit pips, peat, wood, charcoal, peat coke, lignite, brown coal, cannel coal, anthracite &c., is charged by way of a hopper 5, shoot 6, and conveyer 2, while the product is withdrawn by a shoot 10 into a valved controlling vessel 11. Steam, vapours, and gases may be introduced by conduits 12, 13 and the waste gases re- 'moved bv a conduit 19, dust collector 20 and water seal 21, any fine material carried by the gases being deposited either in the chamber 20 or in the chamber 9. The casing 2 may be maintained at a pressure higher than atmospheric and higher than that in the member 1 such as by injection of steam, and is provided with water sumps 14, 15 for cooling and collecting dust. Any excess pressure in the various parts is removed by safety-valves 16, 17, 18. The furnace member 1 may be of steel lined with firebrick, which may be provided with inlets or longitudinal channels for the admission of gases to the activating process or for the admission of combustible gases for heating by surface combustion, and to this end the outer ends of the member 1 may be closed as far as the inner lining with a chrome nickel or steel alloy plating provided with a flanged opening connected by a flexible tube with the gas main. Spiral ribs or the like may be formed by the special setting of the lining of the member 1. A plurality of tubular or other furnaces in one or more casings may be combined to form a battery, the charge being passed consecutively therethrough. Baffles such as longitudinal rods or tubes may be provided in the rotary tube, and these may themselves be heated by gases or electrically, and if tubes are used, these may divide up the chamber into a manifold of smaller furnaces. The rods may also be arranged transversely in staggered layers, and may be of silica, fireclay, or magnesia. The heating may be external and/or internal, in the latter case by injection of liquid fuel, such as crude mineral oil, petroleum or benzene, or illuminating gas, coke oven gas, Mond gas, generator gas or even powdered coal or the like. Suitable activating or purifying gases are steam, carbon dioxide, sulphur dioxide, chlorine, volatile chlorides, hydrochloric or nitric acid, and ammonia. The finished product may be cooled by inert gases such as nitrogen, chlorine, or sulphur dioxide. The various conditions of the process may be so selected as to yield the novel products described in Specification 228,582. One Provisional Specification refers also to the use of other forms of moving furnaces such as a reciprocating furnace member, for example ,a partially open or closed tray of the " grasshopper " type.