Patent GB-783504-A (GB)
Title: Continuous reactors suitable for use in the ageing of alkali cellulose
IPC: B01J8/20
Filed: 1955-01-13
Abstract: <PICT:0783504/III/1> <PICT:0783504/III/2> <PICT:0783504/III/3> <PICT:0783504/III/4> <PICT:0783504/III/5> <PICT:0783504/III/6> <PICT:0783504/III/7> <PICT:0783504/III/8> <PICT:0783504/III/9> <PICT:0783504/III/100> <PICT:0783504/III/111> A continuous reactor suitable, for example, for the production of aged alkali cellulose by the processes described in Specifications 783,505 and 783,506, [both in Group IV (a)], and adapted to allow the passage through a reaction zone of all parts of a stream of liquid in approximately the same time, comprises a vessel with closed ends, means for feeding liquid continuously into the vessel, means in the vessel for dividing the liquid into separate batches of substantially equal size and moving these separate batches along the vessel, and means for discharging the liquid from the vessel, the dividing and moving means including a rotatable helical vane in the vessel having a number of convolutions, the arrangement being such that liquid entering the vessel in a continuous stream at a constant rate of flow is divided into equal batches each contained in a moving compartment bounded by adjacent convolutions of the helical vane and that part of the wall of the vessel that lies between them and that no solid or liquid material can pass from one compartment to another during the normal operation of the reactor by rotating the helical vane and continuously introducing liquid into and discharging it from the vessel at an appropriate rate.  In order to keep each batch of liquid adequately mixed during its passage through the reactor, baffles may be mounted between each adjacent pair of convolutions of the helical vane.  The invention is described with respect to the ageing of alkali cellulose suspended in an aqueous solution of caustic soda.  As shown in Fig. 1, a continuous stream of aerated slurry of alkali cellulose to be aged is delivered from the lower end of a stationary feeding pipe 33 projecting into the inlet aperture 16 of the reactor 11 which comprises a cylindrical thermally-insulated shell 12 having end plates 13 and 14 provided with inlet and outlet apertures 16 and 17 respectively.  The shell 12 is mounted for rotation about its long horizontal axis by means of rollers (not shown) engaging tyres 18 circumferentially disposed about the shell.  Within the shell is a single helical vane 19 whose outer edge is attached to and forms a liquid-tight joint with the inner surface of the shell.  The helical vane 19 is disposed about a cylindrical hollow core 21 extending the length of the shell 12, and the ends of the vane abut against and are welded to the end-plates 13 and 14 along lines extending radially on the end plates.  At its ends the core 21 is provided with specially shaped delivery and discharge slots 22 and 23 respectively, for providing means for the passage of liquid from the interior of the core into the shell and vice versa.  The portion of the core lying between these slots is sealed off from the slots and from the remainder of the apparatus.  The continuous stream of slurry delivered from the lower end of the pipe 33 falls through the delivery slot 22 and into the annular space between the end-plate 13 and the first convolution of the vane 19.  The rotation as one unit of the shell 12, vane 19 and core 21 causes the slurry to move through the shell from the inlet to the discharge end.  The rate of feed of the slurry through the pipe 33 and the rate of rotation of the shell 12 are so correlated that the level of the slurry in the shell does not rise above the top of the core 21, thus causing the spaces between adjacent convolutions of the vane 19 to act as separate compartments so that the slurry passes through the reactor in the form of separate successive batches.  The shape and size of the delivery slot 22 are defined by the delivery member 29 (see Figs. 1, 3, 5 and 8) and are such as to divide the continuous stream of slurry delivered from the pipe 33 into a series of separate batches of equal sizes.  The delivery member 29 (see Fig. 8) has an arcuate front edge 37 covering an arc of about 60 degrees welded to the end-plate 13 of the shell, and a rear edge 38 also in a vertical plane, welded to the core 21, and constituting a complete circle. The delivery member 29 also has a horizontal straight edge 39 joining at its front and rear edges 37 and 38, and another horizontal straight edge 41 leading from its front edge 37 to a helical edge 42.  The helical edge 42 abuts against and is joined to the vane 19 and has the same pitch.  The vane 19 is joined to the delivery member 29 also along a helical line 43 (shown dotted in Fig. 8).  The reactor is preferably so proportioned that the slurry in the compartment closest to the inlet end of the shell 12 reaches to, or near, the lower portion of the core 21 and that in subsequent compartments the level of the slurry should rise almost to the top of the core 21.  This rise in the level of the surface of the liquid is effected by constructing the pitch of the vane 19 so that it decreases to a constant value over the first few convolutions, the decrease in pitch preferably being sufficient to compensate for the decrease in volume of the aerated slurry due to the loss of part of the air which it contains.  A series of baffles 44, each of parallelogram shape and provided with opening 45 are provided between each pair of adjacent convolutions of the vane 19 to agitate gently the batches of aerated slurry as they move through the shell 12 (see Figs. 3 and 4).  At the discharge end of the reactor the pitch of the vane 19 again increases so as to cause the level of slurry in the shell to drop to a height about level with the bottom of the core when the rate of feed of slurry to the reactor is equal to its maximum designed capacity.  At the discharge end of the reactor the space between the last half convolution of the vane 19 and the end-plate 14 is sealed off from the rest of the reactor by a flat lifting plate 46, which extends from the core 21 to the inner surface of the shell 12 and is welded to the vane 19, end-plate 14, shell 21 and discharge member 31.  It serves to help direct the aged slurry through the discharge slot 23. The sheet metal discharge member 31, illustrated in Figs. 6, 7, 10, 11 and 12 has three edges located entirely in vertical planes, namely a semi-circular outer edge 47, extending over an arc of 180 degrees and abutting against the end-plate 14 around the outlet aperture 17, a circular inner edge 48 welded to the core 21, and an intermediate arcuate edge 49 having the same radius as the outer and inner edges 47 and 48, and extending over an arc of about 240 degrees.  A straight horizontal edge extends from a corner 52 (Fig. 10), at one end of the intermediate edge 49 to a corner 53 at one end of the outer edge 47.  A helical edge 54 extends over an arc of about 60 degrees from a corner 56 at the other end of the outer edge 47, and is connected to a relatively short horizontal edge 57, running from the other end 58 of the intermediate edge 49.  The lifting plate 46 is joined to the discharge member 31 along the longer horizontal edge 51, the length of this edge being equal to half the pitch of the vane 19, and the vane 19 is joined to the discharge member 31 along the helical edge 54 and also along the helical line running from the edge 54, through the corner 52, all round the discharge member 31, as shown in Fig 6.  The aged alkali cellulose slurry discharged from the shell 12 through the outlet 17 passes through a discharge nozzle 59 (Figs. 1 and 2), fixed to the end-plate 14, and then into a tapered sump tank 61 having an outlet pipe 62 at the bottom.ALSO:A continuous reactor suitable, for example, for the production of aged alkali cellulose by the processes described in Specifications 783,505 and 783,506 and adapted to allow the passage through a reaction zone of all parts of a stream of liquid in approximately the same time, comprises a vessel with closed ends, means for feeding liquid continuously into the vessel, means in the vessel for dividing the liquid into separate batches of substantially equal size and moving these separate batches along the vessel, and means for discharging the liquid from the vessel, the dividing and moving means including a rotatable helical vane in the vessel having a number of convolutions, the arrangement being such that liquid entering the vessel in a continuous stream at a constant rate of flow is divided into equal batches, each contained in a moving compartment bounded by adjacent convolutions of the helical vane and that part of the wall of the vessel that lies between them and that no solid or liquid material can pass from one compartment to another during the normal operation of the reactor by rotating the helical vane and continuously introducing liquid into and discharging it from the vessel at an appropriate rate.  In order to keep each batch of liquid adequately mixed during its passage through the reactor, baffles may be mounted between each adjacent pair of convolutions of the helical vane. As shown in Fig. 1, a continuous stream of aerated slurry of alkali cellulose to be aged is delivered from the lower end of a stationary feeding pipe 33 projecting into the inlet aperture 16 of the reactor 11 which comprises a cylindrical thermally insulated shell 12 having end plates 13 and 14 provided with inlet and outlet apertures 16 and 17 respectively.  The shell 12 is mounted for rotation about its long horizontal axis by means of rollers (not shown) engaging tyres 18 circumferentially disposed about the shell.  Within the shell is a single helical vane 19 whose outer edge is attached to and forms a liquid-tight joint with the inner surface of the shell.  The helical vane 19 is disposed about a cylindrical hollow core 21 extending the length of the shell 12, and the ends of the vane abut against and are