Patent GB-850597-A (GB)
Title: Improved control system and apparatus for catalytic processes
IPC: C08F2/00
Filed: 1957-02-20
Abstract: <PICT:0850597/IV(a)/1> <PICT:0850597/IV(a)/2> A process for controlling a liquid phase catalytic reaction in a closed reaction zone, wherein there is a liquid phase and a vapour phase, comprises continuously introducing catalyst to the zone, sensing pressure changes within the zone, producing a signal in response to the pressure change, and regulating the flow rate of catalyst or reactant in accordance with the signal so as to compensate for variations in catalyst activity thereby to maintain the pressure within the zone within predetermined limits.  The catalyst feed rate may also be controlled as a function of the reactant feed rate.  The process is described with reference to the polymerization, or copolymerization, of olefines e.g. ethylene, propylene, 1-butene, 1-pentene or butadiene, with a catalyst comprising chromium oxide (preferably at least 0,1% by weight thereof, based on the total catalyst, being hexavalent) associated with at least one of silica, alumina, zirconia and thoria.  In Fig. 1 the process is conducted in reactor 10 fitted with heating/cooling jacket 11 supplied through line 12.  The system is subject to the following controls.  (1) Controller 26 regulates the discharge of heat exchange medium through line 13 by means of valve 28 to maintain a constant temperature measured by element 27. (2) Controller 18 regulates the flow of solvent through line 16 by means of valve 17 to maintain a constant flow rate measured by element 19.  (3) Controller 23 regulates the withdrawal of product to receiver 38 through line 25 by means of valve 24 to maintain the liquid level 22 constant.  (4) Controller 31 regulates the flow of reactant feed through line 29 by means of valve 32 to maintain a constant pressure in the reactor measured by element 47.  (5) Controller 36 regulates the flow of catalyst from feeder 33 through line 34 by adjusting the speed of motor 35 to maintain a constant feed rate measured by element 37.  Fig. 2 describes modifications suitable for use when the reactant is derived from a high-pressure source and is contaminated with inert diluents.  Controller 40 operates pressure reducing valve 39 in response to the pressure in line 29 between valves 39 and 32 as recorded by recorder 43. Analyser-controller 46 measures the ethylene concentration in vent line 44 and operates valve 45 to discharge diluted reactant.  In this modification the catalyst addition rate is not varied. Specifications 790,195 and 804,641 are referred to.ALSO:<PICT:0850597/III/1> <PICT:0850597/III/2> A process for controlling a liquid phase catalytic reaction in a closed reaction zone, wherein there is a liquid phase and a vapour phase, comprises continuously introducing catalyst to the zone, sensing pressure changes within the zone, producing a signal in response to the pressure change, and regulating the flow rate of catalyst or reactant in accordance with the signal so as to compensate for variations in catalyst activity thereby to maintain the pressure within the zone within predetermined limits. The catalyst feed rate may also be controlled as a function of the reactant feed rate.  The process is described with reference to the polymerization or copolymerization, of olefines e.g. homopolymerization of ethylene, propylene, 1-butene or 1-pentene and copolymerization of ethylene with propylene, 1butene or butadiene, with a catalyst comprising chromium oxide (preferably at least 0.1% by weight thereof, based on the total catalyst, being hexavalent) associated with at least one of silica, alumina, zirconia and thoria. The polymerization is preferably effected in a hydrocarbon solvent e.g. isooctane, as described in Specifications 790,159 and 804,641. In Fig. 1 the process is conducted in reactor 10 fitted with heating/cooling jacket 11 supplied through line 12.  The system is subject to the following controls.  (1) Controller 26 regulates the discharge of heat exchange medium through line 13 by means of valve 28 to maintain a constant temperature measured by element 27.  (2) Controller 18 regulates the flow of solvent through line 16 by means of valve 17 to maintain a constant flow rate measured by element 19. (3) Controller 23 regulates the withdrawal of product to receiver 38 through line 25 by means of valve 24 to maintain the liquid level 22 constant.  (4) Controller 31 regulates the flow of reactant feed through line 29 by means of valve 32 to maintain a constant pressure in the reactor measured by element 47.  (5) Controller 36 regulates the flow of catalyst from feeder 33 through line 34 by adjusting the speed of motor 35 to maintain a constant feed rate measured by element 37.  Fig. 2 describes modifications suitable for use when the reactant is derived from a high-pressure source and is contaminated with inert diluents.  Controller 40 operates pressure reducing valve 39 in response to the pressure in line 29 between valves 39 and 32 as recorded by recorder 43.  Analyser-controller 46 measures the ethylene concentration in vent line 44 and operates valve 45 to discharge diluted reactant.  In this modification the catalyst addition rate is not varied.