Patent GB-242659-A (GB)
Title: Improvements in the process of and apparatus for, manufacturing active carbon
IPC: C01B32/336
Filed: 1925-11-06
Abstract: 242,659. Algemeene Norit Maatschappij, (Assignees of Sauer, J. N. A.). Nov. 8, 1924, [Convention date]. Charcoal.-The whole of the gases used in the activating stage of the process of making activated carbon from raw or pre-distilled carbonaceous materials of every description is supplied either alone or mixed with heating gases transversely to the axis of the retort and throughout its whole length and are then caused to pass in a direction parallel with the axis of the retort either in the same direction or in countercurrent to the carbonaceous material. The retort employed may be vertical, horizontal or inclined and may be provided with heating surfaces to facilitate the passage of heat from the gases to the materials under treatment. Examples mentioned of activating gases are steam, air, oxygen, carbon dioxide, products of combustion, ammonia, chlorine, hydrochloric acid, vaporized chlorides and combustible gases mixed with air. When it is desired to remove mineral constituents sulphur dioxide or hydrofluoric acid may be used. More than one activating gas may be employed, successively and at different temperatures. The raw materials prior to the heating and gas-activating processes may be mixed with dry organic or inorganic materials or be soaked or boiled with organic or inorganic liquors or solutions. In the retort shown in section in Fig. 1, the raw material is dried, distilled or carbonized in the first zone 1; it then passes to the second or activating zone 2 and finally reaches the third zone 3 which may be used for cooling or for " burning" the activated carbon. The first and last zones may be omitted from the apparatus. Combustible gases supplied by a pipe 17 are conveyed to an inner passage 8 which communicates by means of ports 9 with the activating zone. Ports 10 lead from the bottom of the latter to a surrounding chamber 11 in which the gases produced by the activating process are burned, and encircling the chamber 77 are further channels 13. 15 into which air and activating gases are introduced through pipes 14 and 16 respectively. The air and activating gases are thus preheated before they enter the central passage 8. By means of baffles 20 in an upper extension of the chamber 11 the hot gases are made to pass round the zone 1 into which they ultimately enter through ports 22. After heating the raw material the gases pass through ports 24 to a central passage 23 and to a passage 25 leading to apparatus for the recovery of by-products, for example a tar separator 26. Uncondensed gases may be returned to the passage 8 and used for heating the retort. The active carbon is continuously withdrawn from a tank 5 which is provided with a water seal. Instead of providing a central passage for the combustible gases and a. chamber surrounding the retort, the gas supply and the discharge chamber for the gases may be disposed at the opposite sides of a retort of rectangular horizontal section. A rotary retort having a perforated gas supply pipe disposed along the whole length of the activating zone may also be employed. Fig. 2 shows a modified kiln in section in which finely powdered material charged into a hopper 31 is activated as it passes down an annular chamber 30 and after passing through grates 32, 33 is further activated as it floats down a channel 38. Activating gases which may be mixed with heating gases enter the apparatus through a pipe 34 and are conveyed to the space above the grate 33 by the passage 37 and to the whole length of the activating zone 30 by means of an annular channel 35 and ports 36. After separation of the active carbon air is admitted and the gases pass through opening 40 and are burned in the surrounding flues 41. In Fig. 3, the retort consists of a series of inclined units 50 which may be completely filled with the material under treatment or the latter may be caused to slide down the inclined walls of the retort in the form of thin layers. The walls are provided with ports 54 through which activating gases supplied by pipes 52 and passages 53 are introduced. The activated carbon produced is discharged at 55 and the gases are burned in the chambers 57. The spent gases can be used for heating the retort internally by passing them through a pipe 59 to the pipe 52.