Patent GB-656584-A (GB)
Title: Improvements relating to apparatus for treating water
IPC: C02F1/42
Filed: 1948-09-01
Abstract: 656,584. Purifying liquids. PERMUTIT CO., Ltd. (Permutit Co.). Sept. 1, 1948, No. 23083. [Class 46] An i o n - exchange apparatus comprises two groups of pressureoperated valves, one group being open during treatment and the other group being open during regeneration, and associated with each group is a constriction in series with a control valve which is closed during treatment and is opened during regeneration to allow some liquid to flow to a point at low pressure. This flow establishes at the constriction a pressure drop and hence a rise or fall of pressure which is transmitted to the control chambers of the valves of the group. Where a back-washing step is desirable a third group of pressure-operated valves may be provided which are open during back-washing, and associated with them are a third constriction and a third control valve which is open during back-washing. One of the control valves is preferably one of the valves in a group controlled by another of the control valves. In the ionexchange plant shown diagrammatically in Fig. 1, water to be treated is introduced by a pipe 70 through valve 55, distributer 32, ion-exchange bed 31, distributer 37, valve 56 and pipe 78 to a point of use. The control chambers of valves 55 and 56 are connected by control pipes 74 between the outlet of a control valve 60 and an orifice 75 on a discharge pipe 76, and are at zero pressure, control valve 60 being closed. A second system of valves, of which 60 is one the others being 57, 58, 59, have control chambers all connected to a pipe 72 between an orifice 71 and a solenoid-operated control valve 54 which also communicates with the discharge pipe 76, the pipe being supplied with water to be treated so that the control chambers are all under pressure while control valve 54 is closed. To initiate regeneration, Fig. 2, a time switch 80 is turned, causing valve 54 to open and the pressure in control pipes 72 to drop. Valves 57, 58, 59 and 60 thus open. Opening of valve 60 causes the pressure in control pipes 74 to rise so that valves 55 and 56 close. Some of the untreated water is now passed to service through valve 57, while the remainder passes via valve 60, pipe 74a, and orifice 75, via orifice 71, pipe 72, and valve 54, to discharge pipe 76. From the latter the water reaches a head-box 45 at a rate sufficient to ensure an overflow through a waste-pipe 50 and hence a constant head above an orifice 46 leading to a regenerant-containing compartment 41 and an orifice 47 leading to a byepass pipe 48. Rate-of-flow through the orifice 46 is sufficiently small to ensure that the solution passing through a screen 43 is saturated. A restricted overflow 51, 52 from the compartment 41 is provided. The dilute solution flowing along pipe 44 is therefore of known constant composition, which could be varied by adjustment of the sizes of the orifices 46, 47. The solution passes via valve 58, distributer 37, downwards through the bed, then up pipe 33 and via valve 59 to waste-pipe 50. When all the solid regenerant in container 41 has been dissolved, rinsing water follows the same path during the remaining time the switch 80 keeps the valve 54 open When the valve 54 closes, pressure builds up in pipes 72, causing valves 57 to 60 to close. Closing of valve 60 permits fluid remaining in pipes 74 to leak away via constriction 75, the water pressure then opening valves 55 and 56 for normal flow to be resumed. The orifice 71 may be replaced by a Venturi tube or a single-stage injector; the diaphragm control valve 60 may be replaced by a solenoid valve. In a modification, the headbox 45 is dispensed with, the pipe 76 discharging into a funnel leading into pipe 44. Also the restricted overflow 51, 52 is omitted, and there is no connection between pipe 74a and pipe 76. Instead, a separate tank containing several charges of solid regenerant is provided, with a tubular straining element at the bottom communicating with a lower tank by a valve with an apertured diaphragm, spring- biassed to an open position. The pipe 74a communicates with the control chamber of this valve, the aperture in its diaphragm taking the place of orifice 75 of Fig. 1. Immediately after regeneration the lower regenerant tank is full of water, and a twoway flow of water upwards and saturated regenerant solution downwards, via the strainer and valve, begins and continues until the lower tank is full of saturated solution. At the same time softening flow proceeds as in Fig. 1. To initiate regeneration, switch 80 is turned, simultaneously opening valve 54 and a similar valve corresponding to valve 60. Water then passes through pipe 74 at supply pressure into the control chamber of the apertured diaphragm valve on the regenerant tanks, closing it against the spring pressure. Water now flows through the diaphragm aperture into the lower tank only, displacing the higher-specific-gravity regenerant solution through a pipe which extends from the bottom of the lower tank to the regenerant compartment 41 at the level of the former overflow 52. The saturated solution then flows through pipe 44 mingling with water flowing from the funnel fed by pipe 76 and passes downwards through the bed to waste as before. Rinsing also follows when the lower regenerant tank has had all its saturated solution displaced. On the closing of the valves 54 and 60, normal softening flow resumes, the apertured diaphragm valve on the regenerant tanks opens, and the two-way solution forming flow recommences. To overcome supplypressure variations a head-box with an overflow and a somewhat restricted outlet may be provided for feeding the funnel leading into pipe 44. In a further modification of the arrangement of Fig. 1, the head-box 45 is dispensed with, the pipe 76 discharging directly into compartment 41, and two solenoid-operated control valves are provided, together with an additional orifice and further diaphragm valves to provide a back-washing step in treating turbid water. The time switch causes the opening of the solenoid valve controlling the backwashing step and then that controlling the regenerating step, one after the other, for fixed periods. In this embodiment. two of the orifices are formed in the diaphragms of two of the diaphragm valves. Figs. 9 and 19 to 22 show a plant operating according to the method of Figs. 1 and 2, comprising a tank 200 corresponding to the tank 30, having upper and lower distributers 232 and 204, Fig. 19, respectively, and a superimposed regenerant compartment 220 (corresponding to 41, Fig. 1), provided with a flat face 219 having a cavity 253, Fig. 22 (head-box 45), with weir 257 (upper pipe 50) leading to cavity 255, Fig. 19 (pipe 50) and a cavity 254 (pipes 48 and 44), Fig. 21, with an aperture 259 (weir 49). The valve now chambers and lateral connections of Fig. 1 are provided in a valve body 280 with appropriate cavities and apertures, the diaphragms are all constituted by a single sheet of flexible rubber 370 and the control chambers are formed in a valve cover 335. During normal flow raw water is introduced at an elbow 295, Fig. 9, attached to an edge of the valve body 280 and communicating with passage 283, Fig. 19, and then passes through valve 300, passages 289, 263, and pipe 213 to the lower distributer 204. Softened water issues from the upper distributer 232 into a compartment 231 (38, Fig. 1), thence along passage 264, Fig. 20, cavity 288, valve 301, cavity 284, and out to service by elbow 296, Fig. 9. The remaining valves 302 to 305 are shut. When regeneration is required the user removes and inverts a lid 247, Fig. 19, and uses the cavity 250 in it as a measure for solid regenerant which falls into the compartment 220 when the lid is replaced. A time switch 416 is then rotated, causing a solenoid valve member 358, Fig. 22, to be withdrawn. Water in supply cavity 283, orifice 321 (71), and cavity 355, passages 356, 329, cavitv 286 and cavity 253, Fig. 22, which communicates with 220 through opening 258 and is thus at atmospheric pressure. Some overflows the weir 257, Fig. 19, into waste cavity 255, thence through passage 275, cavitv 290, Fig. 22, and waste elbow 297. Fig. 9 The remainder passes through orifice 260 (46) into compartment 220 and through orifice 261 (47). Fig. 22, into byepass cavity 254, Fig. 21. where it meets saturated solution formed by the first stream, flowing from below a supporting gauge 241 and along passage 265 into cavity 254. The dilute solution passes through passages 272, 315, through valve 303 into cavity 288, and thence into compartment 231, Fig. 20, and the bed 239 through the upper distributer 232, Fig. 19. It leaves the bed by the pipe 213, passage 263. cavity 289 valve 304, Fig. 22, passage 290, and waste elbow 297. When all solid regenerant has been dissolved raw water follows the same paths to rinse the bed 239. Opening of the valve 358 relieves the pressure in chambers 339, 340, 341 and 342, so that valve 302, Fig. 20, also opens, letting raw water from inlet cavity 283 pass through it into cavity 284, which is in communication with service outlet elbow 296. When valve 358 is closed by the time switch 416, normal flow is resumed.