Patent GB-741225-A (GB)
Title: Improvements in or relating to the conversion of hydrocarbons into lighter hydrocarbons
IPC: C10B55/06
Filed: 1952-03-06
Abstract: In a process for the conversion of a heavy hydrocarbon oil into dry coke and hydrocarbon vapours by contacting the oil with a downwardly-moving, compact mass of hot solid particles (e.g. of petroleum coke) which supply all the heat required for the conversion, the upper part of the reaction zone is provided with a transition cone which tapers gradually upwards and joins a mixing conduit which is of less cross-sectional area than the reaction zone, and the oil is supplied to the interior of the mass of hot particles while it is flowing through this mixing conduit whereby a foam of unvaporized oil and vapours is formed which, together with the pressure drop in the transition cone, ensures that the particles are completely "wetted" by the oil before they enter the reaction zone. The lower part of the reactor is preferably conical, and is provided with banks of shallow baffles which subdivide the flow of particles into a plurality of streams leading to the outlet pipe in the base of the reactor. <PICT:0741225/III/1> <PICT:0741225/III/2> <PICT:0741225/III/3> <PICT:0741225/III/4> Coke particles at 850 DEG -1100 DEG F are fed from hopper 12 (Fig. 1) through line 14 into mixing conduit 154; and the oil, preheated to 650 DEG -850 DEG F, is supplied through conduit 16 and one or more of the feed-conduits 18. Each feed conduit 18 is insulated and the inner pipe 156 (Fig. 6) is provided with a tip 160 so that the oil flows uniformly into the coke column passing the feed point. Thermocouples are inserted adjacent to and below the discharge point of each feed conduit.  Mixing conduit 154 is joined to reactor 10 by transition cone 162 which is at an angle of about 30 degrees with the vertical; and the mixture of liquid and vapours, resulting from the initial contact of oil and hot coke, passes through a depth of gravity-packed bed before entering reactor 10. The particles remain in the reactor for 5 to 40 minutes during which the oil is cracked to form vapours and dry coke, the latter being deposited on the particles.  The coked particles are stripped by steam introduced through inlet 64.  The product vapours pass through slots 56a (Fig. 2) in central pipe 56 beneath collecting cone 58, and are withdrawn through outlet 22.  The formation of a central static zone of particles is eliminated by superposing a frusto-conical baffle plate 65 on cone 58, the distance between the two being at least six to eight particle diameters.  The bottom 10a of the reactor is conical and has an angle of 45 degrees.  Within this cone are mounted three banks of splitter plates 52 (Fig. 3).  In the lowermost bank there are 12 plates, in the next higher bank 24 plates, and so on.  Above the cone 10a is an inverted cone 54, which supports the vapour draw-off assembly.  Cone 54 produces an annular flow of particles to the plates 52; and the flow is then subdivided into independent streams passing to outlet 20.  Radial rods 60, mounted on concentric grid 61 and steam sparger pipe 62, also subdivide the flow of particles.  The zone above pipe 62 and cone 58 constitutes the stripping zone.  The flow of the withdrawn particles through outlet 20 is controlled by valve 51.  The particles are heated to 900 DEG -1300 DEG F in heater 24, either by contact with the products of the combustion of fuel gas supplied through inlet 26, or by partial combustion of the coke coating on the particles.  The combustion gases are withdrawn through outlet 28.  The re-heated particles are passed through pressure-drums 30 or 32 alternatively, and thence into blow case 38.  The particles are then lifted to separator 44 by gas or steam supplied through line 40.  The particles flow from separator 44 into hopper 12 from which some return to mixing conduit 154, the nett make of coke being withdrawn through outlet 50.  Specification 741,277 is referred to.