GB1102810A - Improvements in or relating to the handling of slurries - Google Patents

Abstract

<PICT:1102810/C1/1> A slurry of a granular solid and a liquid, e.g. a slurry of activated carbon for the purification of water in a supply tank 18 is fed to a receiving tank 19 via a chamber 10, the transfer of slurry from tank 18 to chamber 10 and from the chamber to the tank being controlled by valves 21, 23, 25, 27, 29 opened under the control of time switches 43 and 44. The time switch 43 causes solenoid valves 31, 32 to connect the valve operating mechanisms of valves 21, 23 and 25 to a source of fluid under pressure and slurry is transferred from tank 18 to chamber 10, liquid flowing into tank 18 from pipe 20 and excess liquid flowing to an outlet through strainer 13 and pipe 24. After the time set by the timer 43 has elapsed the operating mechanisms of the valves 21, 23 and 25 are connected to exhaust and an impulse is sent to time switch 44 which actuates solenoid valve 33 controlling the operating mechanisms of valves 27 and 29. Liquid is fed through pipe 26 to chamber 10 which discharges slurry to tank 19 until the level of slurry in chamber 10 is such that a photo-electric cell 17 is activated by a light source 16 through rectangular windows 14 and 15 in the chamber. The cell 17 actuates a switch which causes the solenoid valve 33 to connect the operating mechanisms of valve 27 and 29 to exhaust and the transfer to tank 19 is stopped. After the time set by timer 44 has elapsed, a pulse is sent to a counter 45 which in turn may send a pulse to reactivate time switch 43 for the start a further cycle of operations. The counter may be set to operate continuously or it may be associated with a control device set to provide a selected number of cycles of the device. The quantity of slurry transferred at each cycle may be adjusted by varying the vertical position of the light source 16 and cell 17. A single solenoid valve may control valves 21, 23 and 25 or separate solenoid valves may be provided for each valve. In a further embodiment, Fig. 2 (not shown), the light source (16) and cell (17) are placed on opposite sides of a transparent pipe between the base of the main chamber (10) and the connection (28) to the receiving tank. To adjustably control the quantity of slurry fed to the main chamber (10) an extension (56) of the slurry supply pipe (22) is adjustably positioned in the chamber. The level of the lower end of the extension pipe (56) determines the upper level reached by the slurry. In a third embodiment, Fig. 3 (not shown), the termination of slurry transfer from the main chamber (10) is produced by a ball float (60) which floats in the slurry but sinks in the liquid. The ball blocks the outlet pipe (28) when substantially all the slurry has been transferred. A further pipe (61), having a strainer (63), provides a supply of liquid to the outlet pipe (28) for raising the float (60) to the top of main chamber (10) when foll of slurry. In a fourth embodiment, Fig. 4 (not shown), a valve-controlled liquid disposal pipe (91) is connected to the outlet of the main chamber via a strainer (63).