Patent GB-706329-A (GB)
Title: Improvements relating to the treatment of flowable materials
Inventor: BATES HAROLD
IPC: B01J19/18
Filed: 1950-12-06
Abstract: A continuous process for the physical or chemical treatment of a flowable material, e.g. a solution or suspension of a cellulose derivative, comprises the features of passing the material through a series of communicating chambers of which each successive pair is of constant aggregate volume, increasing, substantially up to that volume, the volume of the leading chamber and the following chamber alternately of each pair simultaneously, and supplying fresh material to the rearmost chamber of the series while the volume thereof is increasing, at a rate substantially equal to the rate of increase of the volume of that chamber.  The process may be employed in the esterification of cellulose and in the ripening and stabilization of a cellulose ester, e.g. cellulose acetate. It may also be used in carrying out other chemical reactions in flowable materials in the form of solutions, suspensions, emulsions, or slurries, where uniformity of treatment is desired. The process may also be used for the homogenizing or attemperating of mixtures, or the heating or cooling of materials to a uniform temperature.  The process may be carried out in apparatus comprising a series of cylinders communicating with one another end to end, a piston in each cylinder formed with a passage through its thickness, and a common piston rod on which all the pistons are mounted, the lengths of the cylinders exclusive of the thicknesses of the pistons therein being substantially equal. Preferably a non-return valve is provided in one of the end walls of the series of cylinders, and a non-return valve is also provided in the passage through one or more of the pistons. The valves may be actuated automatically by pressure differences in the material on the two sides thereof, or they may be positively actuated by mechanical means.  Instead of providing valves in the treatment vessel itself, <PICT:0706329/IV (a)/1> <PICT:0706329/IV (a)/2> <PICT:0706329/IV (a)/3> <PICT:0706329/IV (a)/4> a separate pump may be provided, actuated in time relationship with the piston rod, to supply the required fresh material to the first chamber.  As shown in Figs. 1 and 2, the treating vessel comprises a tube 7 formed in sections which are bolted together by end flanges 8, and each section is separately provided with a jacket 9 through which heating or cooling fluid may be passed. The tube 7 has a stainless steel liner divided into short lengths 12 between which are clamped phosphorbronze discs 13.  End plates 16, 17 engage the end sections of liner 12 and are drawn up by clamping bolts 18 so as to clamp the discs 13 in position.  A passage 23 extends through each disc 13 near the upper edge, and each disc 13 is bored centrally for the passage of a piston rod 24.  The piston is covered with lengths of stainless steel jacketing 25 to fit the central holes in discs 13.  A phosphorbronze piston 26 is clamped between each length 25 of jacketing and each piston has a bore near its edge.  One piston is thus secured to the piston rod 24 in each of the succession of cylinders 30 into which the tube 7 is divided by discs 13.  The end plate 16 is bored with an inlet passage 34 containing a non-return valve 35 and a similar valve is provided in piston 261 which is nearest to the inlet end of the tube 7.  This arrangement constitutes a pump for forcing the reaction material through the tube 7 to the other end and through an outlet passage in end plate 17.  The piston rod 24 may be bored as at 39 for the reception of a thermo-couple or other device.  The piston rod 24 is coupled at one end to the piston rod 41 of a hydraulic cylinder 42 the two ends of which are connected by pipes 44 to a valve assembly 45.  A gear pump 46 (Fig. 4) supplies an actuating liquid under pressure to pipes 44 alternately.  It is driven at constant speed so as to have a constant volume rate of delivery and so that piston rod 24 is reciprocated at a uniform rate in each direction. The valve assembly comprises a pair of pistons 51 on a stem 52 working in cylinder 53.  Grooves 56 (Fig. 5) constitute an outlet at each end of cylinder 53 and communicate with the inlet 47 of pump 46.  A vertical inlet 58 communicates with the pump outlet 48, and lateral passages 59 communicate with pipes 44.  A piston 61 is loaded by a spring against the pressure of the fluid in cylinder 53.  Two compression springs 69 are provided between the slidable collars 66 and collar 68 which is fixed to an extension 67 of piston rod 41.  A pair of pivoted catches 70 loaded by springs 71 engage one or other of the collars 66.  A yoke 73 connected to piston 61 lifts the catches 70 and releases the collar 66 held by one of them, when piston 61 is moved by fluid pressure.  Thus, when piston rod 41 reaches the end of its stroke and the pressure on the outlet side of pump 46 rises sharply, the catch 70 is released and spring 69 forces collars 66, frame 65, and valve stem 52 to their other position.  The connections effected by the valve assembly are thus reversed and piston rods 41 and 24 are then driven in the opposite direction.ALSO:<PICT:0706329/III/1> <PICT:0706329/III/2> <PICT:0706329/III/3> <PICT:0706329/III/4> A continuous process for the chemical or physical treatment of a flowable material comprises the features of passing the material through a series of communicating chambers of which each successive pair is of constant aggregate volume, increasing, substantially up to that volume, the volume of the leading chamber and the following chamber alternately of each pair simultaneously, and supplying fresh material to the rearmost chamber of the series while the volume thereof is increasing, at a rate substantially equal to the rate of increase of the volume of that chamber.  The process may be employed in the esterification of cellulose and in the ripening and stabilization of a cellulose ester, e.g. cellulose acetate.  It may also be used in carrying out other chemical reactions in flowable materials in the form of solutions, suspensions, emulsions, or slurries, where uniformity of treatment is desired.  The process may also be used for the homogenizing or attemperating of mixtures, or the heating or cooling of materials to a uniform temperature.  The process may be carried out in apparatus comprising a series of cylinders communicating with one another end to end, a piston in each cylinder formed with a passage through its thickness, and a common piston rod on which all the pistons are mounted, the lengths of the cylinders exclusive of the thicknesses of the pistons therein being substantially equal.  Preferably a non-return valve is provided in one of the end walls of the series of cylinders, and a non-return valve is also provided in the passage through one or more of the pistons.  The valves may be actuated automatically by pressure differences in the material on the two sides thereof, or they may be positively actuated by mechanical means.  Instead of providing valves in the treatment vessel itself, a separate pump may be provided, actuated in time relationship with the piston rod, to supply the required fresh material to the first chamber. As shown in Figs. 1 and 2, the treating vessel comprises a tube 7 formed in sections which are bolted together by end flanges 8, and each section is separately provided with a jacket 9 through which heating or cooling fluid may be passed.  The tube 7 has a stainless steel liner divided into short lengths 12 between which are clamped phosphor-bronze discs 13.  End plates 16, 17, engage the end sections of liner 12 and are drawn up by clamping bolts 18 so as to clamp the discs 13 in position.  A passage 23 extends through each disc 13 near the upper edge and each disc 13 is bored centrally for the passage of a piston rod 24.  The piston is covered with lengths of stainless steel jacketing 25 to fit the central holes in discs 13.  A phosphor-bronze piston 26 is clamped between each length 25 of jacketing and each piston has a bore near its edge.  One piston is thus secured to the piston rod 24 in each of the succession of cylinders 30 into which the tube 7 is divided by discs 13.  The end plate 16 is bored with an inlet passage 34 containing a non-return valve 35 and a similar valve is provided in piston 261 which is nearest to the inlet end of the tube 7.  This arrangement constitutes a pump for forcing the reaction material through the tube 7 to the other end and through an outlet passage in end plate 17.  The piston rod 24 may be bored as at 39 for the reception of a thermo-couple or other device. This piston rod 24 is coupled at one end to the piston rod 41 or a hydraulic cylinder 42 the two ends of which are connected by pipes 44 to a valve assembly 45.  A gear pump 46 (Fig. 4) supplies on actuating liquid under pressure to pipes 44 alternately.  It is driven at constant speed so as to have a constant volume rate of delivery and so that piston rod 24 is reciprocated at a uniform rate in each direction.  The valve assembly comprises a pair of pistons 51 on a stem 52 working in cylinder 53.  Grooves 56 (Fig. 5) constitute an outlet at each end of cylinder 53 and communicate with the inlet 47 of pump 46.  A vertical inlet 58 communicates with the pump outlet 48 and lateral passages 59 communicate with pipes 44.  A piston 61 is loaded by a spring against the pressure of the fluid in cylinder 53.  Two compression springs 69 are provided between the slidable collars 66 and collar 68 which is fixed to an extension 67 of piston rod 41.  A pair of pivoted catches 70 loaded by springs 71 engage one or other of the collars 66.  A yoke 73 connected to piston 61 lifts the catches 70 and releases the collar 66 held by one of them, when piston 61 is moved by fluid pressure.  Thus, when piston rod 41 reaches the end of its stroke and the pressure on the outlet side of pump 46 rises sharply, the catch 70 is released and spring 69 forces collars 66, fra