Patent GB-142206-A (GB)
Title: Improved process relating to the decomposition of hydrocarbons and other substances in the liquid and, or, vapour phases
Filed: 1919-02-06
Abstract: 142,206. Mann, W. Feb. 6, 1919. Fatty acids and glycerine, obtaining by decomposing jats &c.-In the thermal decomposition of fats to obtain glycerine, the lower molecular weight products are separated while the higher molecular weight products and undecomposed substances are recained for further exposure to the decomposition conditions, by interposing one or more porous septa between the decomposition chamber and the condenser and receiver. The decomposition conditions may be maintained up to the porous septum; but it is preferred to place the porous septum in a separate chamber inside or outside the decomposition vessel; and a number of diffusion chambers may be used, arranged either in series or in parallel. The invention is applicable to processes carried out either in the vapour or liquid phases; and in the case of the former the removal of the vapour is facilitated and controlled by lowering the pressure on the condenser side of the septum with respect to that on the other side. In an example, heavy oil vaporized in a still, is passed through tubes 2, 3, 4, Fig. 1, partly filled with pieces of alumina, &c., and maintained at a cracking temperature, and of which the tubes 2 and 3 constitute cracking chambers and the tube 4 the diffusion chamber. For this purpose, the latter is provided with a porous tube 12, Fig. II, closed at one end and supported by a flange at the other end; and the porous tube is protected by a perforated shield 13 and an intermediate packing 14 of asbestes &c., holding alumina or other catalyst. The hot vapours leaving the diffusion chamber may be utilized for heating further quantities of oil; and any tar condensed in this chamber is withdrawn through a cock 7, Fig. I. Diffusion chambers may be applied to a still in which cracking may occur both in the liquid and vapour phases; thus the still 29, Fig. VI, is fitted with a head 27 packed with pieces of alumina &c. 16, Fig. V, resting on a grid 26 and provided with a diffusion chamber arranged as in Fig. II. For liquid phase decompositions the apparatus shown in Fig. VII may be used; in this, liquid at the required temperature and under pressure to prevent boiling, is forced through diffusion chambers 31, 33 in series and maintained at a cracking temperature and each provided with a porous tube 32; the non- diffusible residue is withdrawn and mixed with further quantities of liquid. Vapour phase decompositions may also be carried out in this apparatus, especially those in which a large quantity of carbon is produced; in such cases it is preferable to crack in a separate chamber and to pass the vapours through the diffusion chambers maintained at a slightly lower temperature. Diffusion elements in the form of flat porous plates or a coiled porous tube may also be used; thus the tube may be immersed in the liquid and the decomposition products withdrawn either by a pump or by passing a current of gas or steam through the tubes; or, alternatively, the liquid may be passed through the tube and the diffused products collected on the exterior.