Patent GB-339333-A (GB)
Title: Improvements in or relating to the manufacture of paper and the like and the preparation of the pulp
IPC: D21C7/12
Filed: 1929-08-28
Abstract: 339,333. White, A. E., (Mead Pulp & Paper Co.). Aug. 28, 1929. Pulp, preparation of.-In the production of pulp for paper-making from fibrous material by a continuous process, stock of high consistency is treated with a gaseous chlorinating agent, the material being fed down a tower 10, Fig. 1, and subjected to the action oi gaseous chlorine from a tank 52 containing liquid chlorine. Washing liquid is supplied by the pipe 33, and the feed of stock, the supply of chlorine and of the washing liquid is regulated according to the demands made on the supply of treated stock collected in a storage tank 46. The material is fed by an elevator 15 to a hopper 16 and is discharged by a screw conveyer 18 into the tower 10 down which it falls by gravity. A pipe 50 admits chlorine to the tower. The pulp after treatment reaches the bottom of an annular chamber 27 where it is slushed with water from the arms 39 of the pipe 33 which is rotated by a worm 42. The washed pulp overflows the lip 30 and collects in the tank 46. Trapped chlorine in the pulp is neutralized by dechlorinating fluid supplied by a perforated pipe 140. The pressure of chlorine in the tower is used to control the supply thereof. a pipe 67 from the annular chamber 27 leading under a bell 70 in a water tank 71. The rise and fall of the bell is used to complete the circuits of one or other of two solenoids 105, 109, Fig. 3, the movable cores 106 and 110 of which are connected to a vertically reciprocating stirrup 122 and, by deflecting the stirrup, to cause corresponding pawls 123, 124 to engage a ratchet wheel 125 to operate valve 61 for the chlorine feed and valve 66 for the gas outflow as required in order to maintain a column of chlorine of the required depth within the tower. The bell 70 is suspended by an adjustable screw 81 and coil spring 82, the supporting wire carrying contacts for the two circuits of the solenoids 105, 109. Another form of pressure regulating and control mechanism is shown in Fig. 4. In this arrangement the hell 70 is suspended from a balance beam 161 the rise and fall of which makes and breaks contact 180, 181 of the circuit of an electromagnet 185 which, when energized, lifts a. valve 170, allows water to flow from a constant level supply 165 to a chamber 196 to raise a float 197 and so, by links 202, 205 and a pivoted arm 203, operate the valve 208. To overcome the inertia of the balance arm 161 a liquid counterpoise 163 is used. This is connected by a flexible tube 178 through a tube 174 and valve 170 to a constant level supply. The tube 174 has an adjustable syphon 175 which, by lowering the level of water in the counterpoise, upsets the balance of the balance arm and keeps it in oscillation. The provision of a connection 211, Fig. 5 for the float, chamber 196<1> to a U-bend in the off-take pipe 65<1> allows the rise and fall of liquid in the U-bend to act as a valve in regulating the gas outflow, thus dispensing with the float 197 and valve 208 and linkage connections. The sensitivity of the float 197 may be increased by making it in the form of an annular float 216, Fig. 6, and suspending therefrom a chamber 220 connected by a flexible tube 221 to a constant level tank 222. The raising of the float 216 tends to empty the chamber 220 and thus raises the float 216 still further and the movement is used to lift a chamber 227 to run water into the U- bend of the pipe 65". Specification 339,334 is referred to.