Patent GB-857794-A (GB)
Title: Gas flow control means in apparatus for mixing fluids and gas, such as water-chlorinating systems
IPC: C02F1/76
Filed: 1958-03-14
Abstract: 857,794. Mixing fluids. WALLACE & TIERNAN Inc. March 14, 1958 [March 21, 1957], No. 8247/58. Class 86 Apparatus for feeding gas into a fluid conduit, more particularly for chlorinating water, so that the quantity of gas in the fluid is maintained at some predetermined proportion comprises a gas supply conduit in which is an adjustable orifice for regulating the gas flow and at the downstream end of the supply conduit a means 33 for injecting the gas into the fluid. Pressure regulating means in the supply conduit include elements upstream and downstream of the orifice for maintaining a controlled pressure drop across the orifice with corresponding regulation of the gas flow. Control means 147 connected to the main conduit 22 sense changes in the rate of fluid flow and fluid-testing means 150 control the gas feed in response to variations in the composition of the fluid. Chlorine fed from cylinders 20 through a pipe 36 to a chamber 54 when a control valve 196 is opened passes to a pipe 25 at a reduced pressure determined by a reducing valve 24, which controls the movement of a diaphragm 52 to regulate the entry of gas into the chamber 54 through a nozzle 57. The valve 24 is similar to the apparatus described in Specification 708,044 and communicates with the pipe 25 through pipes 58, 60 and a chamber 162 containing a driping agent such as granular metallic zinc, so that the upper surface of the suspended bell 42 is exposed to the gas pressure and the lower surface is exposed to atmospheric pressure by means of a tube 64. Any departure from the balanced condition of the bell causes movement of the diaphragm 52 to increase or decrease the flow of gas until the balance is restored. The gas is fed from pipe 25 to pipe 26 and thence to the adjustable orifice device 28, which comprises a chamber having an apertured partition midway of its length. Through the aperture extends a slidable rod in which is a tapered recess 102, so that by sliding the rod the effective size of the aperture may be changed to control the flow of gas from the ohamber to a feed pipe 29. The recess is preferably shaped to give a flow rate varying exponentially with the displacement of the rod. Actual pressure drop across the device 28 is indicated by a manometer 130 and scale 155: To adjust the rod 98, it is provided with rack teeth which engage a pinion 117 set by means of a knob 140. The pinion 117 drives a pinicn 121 meshing with a rack 120 carrying a pointer 118, which indicates the gas flow on a time chart 124. The position of the rod 98 may be controlled by an electrochemical device 150 governing a reversible motor 152 coupled to the pinion 117, the device 150 being connected to the main conduit 22 to withdraw a sample of the treated fluid. From the pipe 29, the gas passes to a reducing valve 30 similar to valve 24 and controlling the passage of the gas to a chamber 166 from which the gas is drawn into a subsidiary conduit 35 by the suction of the fluid entering the conduit through a valve 197. Should liquid enter the chamber 167 from the injector 33, a float 168 rises and opens a drain conduit 172. In the reducing valve 30, the suspended bell 72 is exposed to the gas pressure on its upper surface and the pressure within the bell is controlled by the pressure within the main conduit 22. To control the latter pressure, a con- . duit 85 extends into the bell from a chamber 165 containing a chlorine absorbent and connected by a pipe 142 to a pressure differential converter 144 governed by the pressure drop along a venturi 145 in the main conduit 22. Fig. 10 shows a pressurereducing valve 201 from which chlorine - flows through a conduit to an adjustable orifice device 203 controlled by a needle 212 moved by means of a rack 116 and pinion 117. From device 203 the gas passes through a constant pressure valve 205 to the main 22. The valve 201 comprises diaphragms 207, 208 rigidly connected by an element 209 and a spring 210, the valve being designed to maintain a pressure dif. ference between conduit 202 and conduit 204 equal to the fall in conduit 144 below atmospheric pressure. Fig. 12 shows an arrangement in which the pressure drop across the orifice 28 is maintained constant and the orifice is adjusted through differential gearing in accordance with the rate of flow in the main 22 and a quantity depending on the need of the fluid for treatment as determined by a device 401. The device 401 produces a direct current at terminals 402 in direct proportion to the need, e.g. of chlorine to give a desired residue in water. Increased flow in the main 22 shifts the armature of a converter 420 and produces electrical unbalance in an amplifier 440, whereupon a motor 416 changes the position of rod 98 to increase the chlorine flow and restores the electrical balance. Increased demand for chlorine switches in a motor 417 to shift the rod 98.