Patent GB-840225-A (GB)
Title: Method and apparatus for controlling a catalytic reaction system
IPC: C08F10/00
Filed: 1957-07-19
Abstract: In the polymerization of olefines in the liquid or vapour phase in the presence of a subdivided catalyst the reaction rate is maintained constant by separating unreacted olefine from the reaction effluent and recycling it to the reaction, controlling the flow of fresh olefine inversely proportional to the rate of flow of the recycle and controlling the flow of catalyst inversely proportional to the flow of olefine feed.  The process can be applied to the polymerization of ethylene, propylene or butylene or the copolymerization thereof with butadiene or isoprene.  Suitable catalysts are chromium oxide containing hexavalent chromium supported on silica, alumina, zirconia, thoria or silica-alumina, titanium tetrachloride with triethyl aluminium or ethyl aluminium halides, or a halide of <PICT:0840225/IV(a)/1> titanium, silicon, zirconium or tin with sodium, potassium, lithium, rubidium, zinc, cadmium or aluminium metal.  Temperatures of 150-450 DEG  F. are employed, preferably at a pressure to maintain liquid phase e.g. 100-700 p.s.i.g.  The catalyst concentration may be 0.01-10% by weight and the reaction residence time 15 minutes-12 hours.  An inert diluent is preferably present in such amount that the olefine constitutes 0.1 to 25% by volume of the mixture, typical diluents being C3-C12 acyclic paraffins and C5-C12 alicyclic hydrocarbons.  The process is particularly suitable for the polymerization of ethylene in the liquid phase; ethylene is introduced into reactor 24 maintained full of liquid by line 2, cyclohexane solvent by line 10 and a slurry of catalyst in cyclohexane by line 12 and pump 14 after mixing with additional cyclohexane from line 19. The reaction effluent passes to flash chamber 30 wherein unconsumed ethylene is vaporized leaving by line 34, while by line 32 is removed polymer product, solvent and catalyst.  The vaporized ethylene is recondensed by passage through pump 38 and is recycled to the reactor by line 40.  Should the reaction rate change the instrumentation compensates automatically. Thus if the quantity of catalyst introduced increases, the conversion of ethylene is increased and the recycle flow through line 40 is decreased.  The recycle material passes through an orifice 42 which produces a pressure differential proportional to the flow rate.  This actuates a Foxboro "d/p" cell 7 which also produces a pneumatic signal proportional to a flow which is fed to a flow measuring and controlling device 6 which transmits a pneumatic signal to a flowcontrolling motor valve 4.  It is arranged that the decrease in flow through orifice 42 produces a proportional increase of ethylene through valve 4.  The ethylene feed passes through a similar orifice 8 actuating d/p cell 15 and flow recorder 16 which transmits to valve 18.  The increased flow through orifice 8 is arranged to increase the flow of cyclohexane through valve 18 and the pump 14 is arranged for constant rate of flow, the flow of catalyst slurry through line 12 is hence decreased; alternatively the flow through orifice 8 can be made to vary the speed of pump 14.  If the flow of ethylene to the reactor (fresh feed+recycle) is to be maintained constant then the orifice 42 can be located downstream from the junction of lines 40 and 2. Specfications 790,195, 804,641 and 831,979 are referred to.ALSO:A process for reacting at least one feed material in the presence of a subdivided catalyst, wherein catalyst and feed are introduced into a reaction zone and the effluent is separated into unreacted feed which is recycled and reaction product is controlled to maintain the <PICT:0840225/III/1> reaction rate constant by controlling the flow of feed material inversely proportional to the rate of flow of the recycle stream and the flow of catalyst inversely proportional to the rate of flow of feed material.  The process is particularly suitable for the polymerization of olefines, e.g. ethylene (see Group IV (a)) in the liquid phase; ethylene is introduced into reactor 24 maintained full of liquid by line 2, cyclohexane solvent by line 10 and a slurry of catalyst in cyclohexane by lines 12 and pump 14 after mixing with additional cyclohexane from line 19.  The reaction effluent passes to flash chamber 30 wherein unconsumed ethylene is vaporized leaving by line 34, while by line 32 is removed polymer product, solvent and catalyst.  The vaporized ethylene is recondensed by passage through pump 38 and is recycled to the reactor by line 40. Should the reaction rate change the instrumentation compensates automatically.  Thus if the quantity of catalyst introduced increases, the conversion of ethylene is increased and the recycle flow through line 40 is decreased.  The recycle material passes through an orifice 42 which produces a pressure differential proportional to the flow rate.  This actuates a Foxboro "d/p" cell 7 which also produces a pneumatic signal proportioned to flow which is fed to a flow measuring and controlling device 6 which transmits a pneumatic signal to a flow-controlling motor valve 4.  It is arranged that the decrease in flow through orifice 42 produces a proportional increase of ethylene through valve 4.  The ethylene feed passes through a similar orifice 8 actuating d/p cell 15 and flow recorder 16 which transmits to valve 18.  The increased flow through orifice 8 is arranged to increase the flow of cyclohexane through valve 18 and the pump 14 is arranged for constant rate of flow, the flow of catalyst slurry through line 12 is hence decreased; alternatively the flow through orifice 8 can be made to vary the speed of pump 14.  If the flow of ethylene to the reactor (fresh feed + recycle) is to be maintained constant then the orifice 42 can be located downstream from the junction of lines 40 and 2.  The process can also be applied to the hydrogenation of unsaturated hydrocarbons or fatty acids, the isomerization of hydrocarbons and the alkylation of aromatic or isoparaffinic hydrocarbons.  Where more than one feed material is involved, e.g. alkylation or copolymerization, the feed materials can be admitted as a single stream of controlled composition or as separate streams controlled so that changes in one stream provides proportional changes in the other or others and unconsumed reactants can be recycled as a single stream or as separate streams with only one stream providing the control.  Specifications 790,195, 804,641 and 831,979 are referred to.