Patent GB-741277-A (GB)
Title: Improvements in or relating to the conversion of hydrocarbons into lighter hydrocarbons
IPC: C10B55/06
Filed: 1952-03-06
Abstract: <PICT:0741277/III/1> In a process for the conversion of heavy hydrocarbon oils into coke and hydrocarbon vapours, wherein the oil is introduced into a moving compact mass of hot solid particles passing through a reactor maintained at a super-atmospheric pressure, and some of the coked particles withdrawn from the reactor are reheated and then returned to the reactor, the coked particles leaving the reactor are transerred as a compact mass to a gas release hopper, the transfer being actuated by the superior pressure in the reactor and by a very small amount of inert gas which maintains the necessary pressure-drop in the transfer-line; the particles are discharged from the hopper, and those which are to be recycled are passed to a reheater.  Hot coke particles wetted with the hydrocarbon oil are fed into the top of reactor 10 which is maintained at a pressure of 15 to 100 p.s.i.g.  As the particles move down the reactor, the oil is converted into vapours and dry coke, the latter being deposited on the particles.  Near the bottom of the reactor, the particles are purged with steam introduced through line 24 and ring 22.  The product vapours are removed under disengager 12, and are withdrawn through outlet 14, quench liquid being supplied through inlet 16.  The coke particles withdrawn from the bottom of the reactor are conveyed as a compact mass through tapered lift conduit 26 to gas release hopper 28 which is maintained at a relatively low pressure by valve 30.  The movement of the particles through conduit 26 is achieved by the pressuredrop between reactor 10 and disengager 28, this pressure-drop being maintained by a very small amount of the steam introduced through line 24.  Coke particles are withdrawn from gas release hopper 28 via valve 32, and are passed through classifier 34 which is provided with screen 36 to separate the largest particles; these are removed through valve 38.  The smaller particles are passed through line 42 into reheater 40 which is provided with burners 48 supplied with air and fuel gas through lines 44 and 46 respectively.  The flue gases are withdrawn through collector 49, outlet 50 and stack 52.  Coke particles of intermediate size pass through screen 36a of the classifier, and are withdrawn through line 75.  Part of this coke is crushed in crusher 76 and passed to reheater 40; the remainder is withdrawn via line 79.  The reheater is operated at approximately atmospheric pressure.  The hot coke particles pass intermittently out of the reheater through outlet 54 and valve 56a into chamber 56 which is at atmospheric pressure. After particle delivery, chamber 56 is put under pressure with steam from line 62.  The particles are then transferred from chamber 56 through valve 58a into high-pressure chamber 58.  Chamber 56 is then vented via valve 78, and the cycle begins afresh.  Valves 56a, 58a, 78 and the valve delivering high-pressure steam to chamber 56 are all controlled by controller 60.  The particles flow continuously from chamber 58 up lift-line 64 into disengager 66, and then up lift-line 70 to the top of reactor 10.  The intermediate disengager is particularly beneficial because of the greater requirements of lifting steam at the bottom of the lift lines than at an intermediate section.  The excess steam is withdrawn from disengager 66 via line 68, and is introduced into purge ring 22.  The manner of mixing the feed oil with the coke particles in line 70, and the baffle arrangements in the bottom of the reactor, are described in Specification 741,225. Specification 705,637 [Group XII], also is referred to.