GB567261A - Improvements in and relating to the automatic control of concentration of solutions - Google Patents

Abstract

567,261. Controlling concentration of ammonia liquid. HOLMES & CO., Ltd., W. C., and COOPER, C. Feb. 16, 1943, No. 2523. [Class 55 (ii)] [Also in Group II] The concentration of an aqueous solution is regulated by balancing a column of the solution against a column of another liquid of constant or approximately constant composition and then causing variations in the difference in height of the columns to vary the supply of water to such aqueous solution. The concentration of ammonia in the gases leaving a gas washer by adjusting the concentration of ammonia liquor in the washer by varying the amount of water fed to the washer in accordance with the difference in density between the liquor and a constant comparison liquid, e.g. water or oils. As shown, a small pipe 1 is threaded into a larger vertical pipe 2 of height from 6-10 feet, the inner pipe being fed with clean water and the outer with ammonia liquor and the two pipes being in communication at the foot 3. Ammonia liquor from the washer 8 is slowly fed through pipe 19 into funnel 20, whence it passes to the foot 3 of the column. Fresh water is supplied by pipe 22 to the funnel 23 terminating pipe 1, pipe 2 being terminated by funnel 24, which is surrounded by the funnel 4 carrying the surplus from the balancing device via pipe 18 to the tank 7. The main water supply is carried via pipe 31 and float valve 5 to tank 6 containing two siphons 10 and 11, the first being always submerged when the water in tank 6 is at its maximum level and continuously siphoning out at a comparatively small rate. Siphon 10 is connected via pipe 14 with the openmouthed tube 15 placed very close to the level of the water in pipe 1 and via pipe 13 with the vertex of the large siphon 11. When tube 15 becomes submerged, the suction created by .siphon 10 draws water into the main siphon 11 which quickly empties tank 6 into tank 7 whence the water passes via pipe 9 to the washer 8 and the action is repeated until the ammonia liquor reaches the desired concentration and the water level in pipe 1 falls to unseal pipe 15 and interrupt the flow. The outlet ends of the siphons are sealed by the small tank 17 in tank 7. A hand-control water feed 16 is also provided. In a modification a central tube charged with oil is provided within the tube 1. In a further modification, to provide for large rates of water admission the discharge from siphon 11 is led into a small vessel riding on the ball of a ball valve controlling the supply of water to tank 7 and hence to washer 8. Siphon 11 is provided with a seal on its length. Temperature changes may be allowed for by arranging the height of the column so that the change of density of the solution due to temperature just balances the change in level due to expansion. The rise and fall in the water level in pipe 1 may be used to tilt a mercury switch and turn on or off a water supply by electrical means. Specifications 162,166, 331,592, 331,818, [all in Class 55 (ii)], and 357,712 are referred to.