Patent GB-512369-A (GB)
Title: An improved catalytic process for vapour phase reactions
IPC: B01J8/00
Filed: 1938-09-29
Abstract: 512,369. Treating solids with gases &c. ; catalytic apparatus ; regenerating catalysts; cracking or polymerizing hydrocarbons. STANDARD OIL DEVELOPMENT CO. Sept. 29, 1938, No. 28379. Convention date, Nov. 13, 1937. [Classes 1 (i) and 32] [Also in Group IV] In the treatment of solids with gaseous reactants, particularly catalytic reactions in the vapour phase such as the cracking or polymerization of oils, in a continuous manner, the solid reactant is moved positively through the reaction zone in the form of a layer of substantially uniform depth and the gaseous reactant is passed through the layer of solid transversely to its direction of motion. In catalytic reactions, the catalyst is preferably regenerated after passage through the zone and returned thereto in a continuous manner. In the arrangement shown in Fig. 3, the reaction chamber comprises an inner perforated shell 14 and an outer concentric shell 15, the space between serving to collect the vapours produced in the reaction. The inner shell 14 contains a central perforated hollow shaft 17, rotated by pinion gear 19, and through which the gaseous reactants are introduced. This shaft carries a spiral flange 22, forming a screw conveyer for forcing the catalyst, which is fed from a hopper 24, through the reaction chamber. Valves 25 control the rate of feed. Preferably the upper convolution of the spiral is of greater pitch so that the catalyst is slightly compressed and more uniformly distributed before introduction into the main treating zone, and the perforations in the shaft 17 may also be omitted at this point. The final products are withdrawn from tne annular chamber by pipes 26 and passed to a suitable recovery system, e.g. a fractionating tower. The apertures in the shaft 17 and the inner shell 14 may be uniformly spaced and sized, or they may be graded to control the amount of products passing through different vertical sections of the chamber. In consequence of the gradually decreasing activity of the catalyst, and the increase in resistance to gas flow due to carbonaceous deposits on the catalyst, uniform apertures provide a selfcompensating method in that time of contact which vary inversely with the activity of the catalyst and give uniform conversion throughout the full length of the catalyst zone. Also, the pitch of the spiral flange may be gradually increased to compensate for the increased volume of the catalyst due to deposited material and give a uniform pressure drop. The apertures may also be inclined to prevent clogging by the catalyst. The catalyst is withdrawn via conveyer 33 and returned after regeneration via conveyer 34. Pressure seals may be provided, so that the reaction may be carried out under increased or decreased pressure or one or more chambers may be withdrawn from multiple installation without interruption of the process. As shown, this seal comprises a rotary valve 36 coupled with a reciprocating valve having spaced plungers 38 and 39 reciprocating in cylinder 41 between the conveyer 33 and the reaction chamber. As applied to the cracking of oils, the vapourized oil is treated in a number of reaction chambers of the form shown connected in parallel, and the reaction products are passed to a fractionating tower 32 (see Fig. 2). Insufficiently cracked products may be collected, as a whole or as fractions, and recycled if desired. Uncondensed constituents are collected in condenser 55 and gases are vented through a valve 59 to maintain the desired back pressure on the cracking system. The catalyst may consist of activated clays, e.g. Fuller's earth, acid-treated bentonites, or synthetic gels and may be in moulded form or deposited on an inert carrier. The spent catalyst is conveyed to a steaming chamber 61 in which volatile constituents are distilled off, and is then regenerated in chamber 63 by means of air, or air diluted with steam. The regenerating furnace may be of the Herreshoff type, or similar to the Dwight-Lloyd sintering furnace or a rotary kiln. After regeneration, the catalyst may be steamed to remove regenerating gases; and is returned to the hoppers of the individual reaction chambers by conveyer 34. If desired, the speeds of the two conveyers may be synchronized, the rotary shafts in the reaction chambers may be driven independently or synchronized, and the speed of the rotary shaft is preferably synchronized with the 'catalyst charging and discharging valves 25 and 36.