GB720630A - Improvements in or relating to photochemical reactors - Google Patents

Abstract

In the production of gamma benzene hexachloride in two stages, a battery of photochemical reactor tubes (see Group III) may be arranged as shown in Fig. 1 wherein chlorine enters through a surge drum 18 of capacity at <PICT:0720630/IV (b)/1> least as great as the combined reactor tubes, to avoid backflow to the gas source. The chlorine is mixed with and preferably completely dissolved in the recycled mixture and fresh benzene at 20; the mixture passes into the first reactor tube 12 and progresses through 13 tubes, after which (generally as a 70 to 95 per cent converted chlorine, benzene and benzene hexachloride solution) it is passed to the recycle hold-up drum 11. The issuing mixture is then split into a recycle stream (generally the major part) which returns through line 34, and a portion which passes into the five "secondary" reactor tubes 13, finally emerging at 37. The reactor zone may be maintained at temperature of about 30 DEG C.ALSO:An apparatus for conducting an exothermic photochemical reaction comprises a light unit, a translucent tube surrounding said light unit, a heat conductive pipe surrounding said translucent tube and forming therewith an annular reaction zone for carrying out said reaction and a rigid metal shell surrounding said heat conductive pipe and forming therewith an annular coolant chamber for removing the heat generated in said reaction. In <PICT:0720630/III/1> <PICT:0720630/III/2> the preferred apparatus, used e.g. for the production of gamma benzene hexachloride, see Fig. 2, a fluorescent tube 46 is the light source. This is surrounded by a transparent or translucent tube 44, preferably of glass, in which is an inert non-conducting liquid 102, such as transformer oil or trichlorobenzene. A resin-impregnated graphite tube 42 encloses tube 44 and forms therewith an annular reaction zone 48. This is maintained at a suitable temperature by concurrent cooling with a coolant which enters through a flexible tube 54 into an annular chamber defined by an outer steel shell 40 and said graphite tube 42. The reactants pass from this reaction zone to a succeeding reaction zone through a connector ell 50 also made from resin-impregnated graphite. Two fluorescent tubes may be placed end to end within each translucent tube 44 and a diagram of a suitable circuit including manually operated excitation to avoid an explosion in the event of breakage, and a warning pilot light, is given. In the production of gamma benzene hexachloride in two stages, a battery of photochemical reactor tubes may be arranged as shown in Fig. 1 wherein chlorine enters through a surge drum 18 of capacity at least as great as the combined reactor tubes, to avoid backflow to the gas source. The chlorine is mixed with and preferably completely dissolved in the recycled mixture and fresh benzene at 20; the mixture passes into the first reactor tube 12 and progresses through 13 tubes, after which (generally as a 70 to 95 per cent converted chlorine, benzene and benzene hexachloride solution) it is passed to the recycle holdup drum 11. The issuing mixture is then split into a recycle stream (generally the major part) which returns through line 34, and a portion which passes into the five "secondary" reactor tubes 13, finally emerging at 37. The reactor zone may be maintained at a temperature of about 30 DEG C.