GB561119A - Improvements in or relating to apparatus for effecting the proportionate addition ofchemicals to liquids flowing through pipe-lines - Google Patents

Abstract

561,119. Mixing. BENSON, C. G., and BELL BROS. (MANCHESTER 1927), Ltd. Nov. 19, 1942, No. 16363. [Class 86] In an apparatus for effecting the proportionate addition of chemicals to liquids flowing through pipe lines, a constant differential pressure is maintained across a restricting orifice or venturi tube in the pipe line with varying rates of flow by means operated by variations in the differential pressure due to variations in the rate of flow to adjust, automatically and correspondingly, the effective area of the restricted orifice or venturi tube to restore the differential pressure to normal, the adjusting means being utilized to control proportionate addition of the chemical to be added to the liquid flowing through the pipe line. The flow in the main pipe is restricted by a plate 10 having an orifice 11 co-operating with a plate 9 connected to a piston 13 in a cylinder 14. Tubes opening into either side of the restriction communicate with ports 26, 27 in a casing for a valve 20 depressed by an adjustable spring 33 and actuated by a piston 22, the upper and lower sides of which are connected by tubes with the main upstream and downstream respectively of the constriction. A port 28 is also connected with the upstream side of the main. Ports 17 and 18 communicate with upper and lower sides, respectively, of the piston 13. In operation, a rise in the differential pressure lifts the piston 22 which raises the valve 20, admitting pressure to the under side of the piston 13 and opening the upper side to exhaust. The plate 9 is thus raised until the normal difference of pressure corresponding to the adjustment of the spring 33 is re-established. Similarly a decrease in the flow in the main causes descent of the plate 9. The movements of a rod 12a connected to the piston 13 are used to vary the amount of chemical supplied to the downstream side of the restriction, e.g. by connecting it with a movable pipe immersed in a tank and so arranged that increase of flow through the main causes increase in head at the intake of the pipe. The movements of the plate 9 may deflect a proportionate width of emulsion or suspension discharging over a constant head weir, or may be arranged to control a pump discharging into the pipe line, or to control the proportionate delivery of reagent in powdered form by operating a slide valve.