Patent GB-719798-A (GB)
Title: Method and apparatus for producing homogeneous viscose
Inventor: KULP MAURICE P
IPC: D01F2/08
Filed: 1952-01-18
Abstract: The process of the parent Specification is modified in that ferrous metal particles are removed from the viscose before it is introduced into the hopper, or the first hopper, the film of viscose on the rolls is periodically removed by doctor blades to maintain the level of the viscose in the hopper or hoppers within predetermined limits, and the operation of the doctor blades is automatically controlled through a signal control which is actuated by the level of the viscose in the hopper or hoppers.  As shown in Fig. 1, a slurry of cellulose xanthate crumbs and dilute sodium hydroxide solution <PICT:0719798/IV (a)/1> is fed from the tank 11 through pipes 13 and 15 and pump 14 to a magnetic separator in which it strikes an inverted V-shaped baffle 16, flows over metal plates 17 having magnets 18 on their underside, inverted V-shaped baffle 19 having magnets 20 on its underside, and into the first hopper 1.  The slurry is mixed in hopper 1 by the smooth closely spaced rolls 3, 4 which form the bottom of the hopper and rotate towards the nip, thus withdrawing some of the slurry from the hopper 1 and discharging it into the hopper 2 in which the slurry is further mixed by the rolls 5, 6 and discharged into the delivery hopper 7 from which the viscose is removed through pipe 8 and pump 9.  When the slurry in hopper 1 reaches the probe 31, contacts in the electronic relay 36 are opened, de-energizing the solenoid spool valve 41, thus allowing air to escape from cylinders 27, which swings the doctor blades 21 against rolls 3 and 4 and causes the viscose to be wiped off the rolls into the hopper 2.  When the viscose in hopper 2 reaches the probe 33, the doctor blades 22 are similarly made to swing against rolls 5 and 6 and the viscose is wiped off the rolls into hopper 7.  When the viscose in hopper 7 reaches the probe 47, the contacts in the electronic relay 39 are opened and the circuit closes in the starter 48 for the motor driving the pump 9 which removes viscose from the hopper 7.  If the viscose should reach probe 32 in hopper 1, the contacts in electronic relay 35 are closed, breaking the circuit in starter 49 for the motor which drives pump 14.  If the viscose reaches probe 34 in hopper 2, contacts in electronic relay 38 are closed, the solenoid valve 41 is energized, taking doctor blades 21 away from rollers 3 and 4, and the viscose continues round the rollers so that none falls into hopper 2.  Similarly, if the viscose reaches probe 50 in hopper 7, doctor blades 22 are moved out of contact with rollers 5 and 6 and viscose is thus prevented from falling into hopper 7. As the level of the viscose falls below the lower end of each probe, the reverse operation takes place so that the viscose in the hoppers is maintained within predetermined levels. The rolls are all the same size, and the lower pair are preferably set closer together and rotated more rapidly than the upper pair. The upper pair of rolls with its associated hopper and level control system may be omitted, the slurry from the magnetic separator being fed direct to the hopper 2.