Patent GB-636742-A (GB)
Title: Improvement in method and apparatus for the use of contact masses
IPC: B01J8/02
Filed: 1947-03-03
Abstract: <PICT:0636742/III/1> <PICT:0636742/III/2> <PICT:0636742/III/3> In a hydrocarbon conversion process (cracking, reforming, or dehydrogenating with or without hydrogen) using a fixed bed of catalytic contact mass which is periodically regenerated, the contact mass has a heat capacity (specific heat x bulk density) greater than 0.45 B.Th.U./litre x  DEG F.; and elements through which heat exchange fluid is continuously circulated, are embedded in the contact mass in a regular manner.  Each element has heat-exchange surfaces attached thereto, the elements being arranged so that the average clearance between the surfaces on adjacent elements is not less than one inch, and the area of the surfaces per unit volume of contact mass being sufficient to ensure that the temperature gradients within the mass are not injurious to the mass and the converter.  The contact mass may be a single material or may comprise a mixture of a catalytic material and an inert refractory having a high heat capacity, such as corundum, fused quartz, or magnesia.  The mixture may comprise separate particles of catalyst and of refractory; or both components may be present in each particle, e.g. the two materials may be mixed in powder form and then formed into pellets. Cracking is carried out at a temperature in the range 700-950 DEG  F., at a pressure from about atmospheric to 100 lbs./sq. inch (gauge), at space rates of about 0.4 to 0.8 vol./vol. x hr., and if necessary in the presence of steam.  Under these conditions less than 5.8 grm. of coke per litre of contact mass is deposited in each 10 minutes of cracking time.  The contact mass for cracking may be a mixture of an activated clay, a silica gel, or zirconium phosphate (65-85 vol. per cent) and a refractory having heat capacity of about 1.1; and 0.3 to 0.7 square feet of heat exchange surface per litre of contact mass is used.  The conversion may be carried out in the converter shown in Fig. 1 wherein the contact mass is supported in chamber 15 bounded by chambers 17 and 18 which are connected to orificed distributors 27 and 32 respectively.  The hydrocarbon vapours are introduced through conduits 38, and the conversion products are removed through port 26.  During regeneration the oxidizing gas is passed through the converter in the reverse direction.  Also within chamber 15 are imperforate elements 33 which have fins 34 and through which heat exchange fluid is circulated via inlet port 39, manifolding chamber 22, the elements, chamber 19, and exit ports 54.  Exterior heat exchange conduits 48 are also provided. Each distributer is surrounded by six elements 33, Fig. 2; and the average clearance between the fins on adjacent elements is greater than one inch.  A shell 24 conforms to the outer boundary of the distributers and heat exchange elements, and the space between it and the casing 10 is insulated.  The fins 95, Fig. 7, on the elements 33 adjacent this boundary have greater volume than those on the elements in the interior of chamber 15, and contact mass of greater heat capacity is employed at the boundary than in the interior. Specification 545,590, [Group XIII], is referred to.