Patent GB-842357-A (GB)
Title: Control system for a battery of centrifugal apparatus
Inventor: JR JOSEPH B BANGE
IPC: H02J3/14
Filed: 1956-08-28
Abstract: 842,357. Centrifugal strainer separators. WESTERN STATES MACHINE CO. Aug. 28, 1956, No. 26308/56. Class 46. [Also in Group XXXVII] A control system for an assembly of cyclical centrifugal separators each having an individual control system for automatically programming it through a predetermined cycle of operations independently of the others is characterised by the combination means for causing each separator to repeat its cycle automatically and a control for the assembly comprising a plurality of actuators each operable to actuate the recycling means of one of the separators, timing means to operate the actuators in predetermined timed sequence, and means for starting the timing means so that the separators are started on their respective cycles in a predetermined timed sequence. Operation of each separator. Eight separators are provided, each having a perforate basket 14 on a rotating shaft 18, discharge valve 26 with lifting device 31 and operating air cylinder 40, discharger shoe 33 and its operating mechanism 29, main motor MM, air-operated brake bands 23, discharge motor DM, discharge drive DD incorporating a clutch (not shown), and a sprayer 32 inside the basket, many of these features being substantially identical with those disclosed in Specification 688,707 [Group II]. For each machine, a complete cycle of operations, automatically controlled by an electric circuit, Fig. 5 (not shown) which includes timers, relays and solenoids operating aircontrolled valves, begins with acceleration up to a speed in the range 225 to 275 r.p.m., wherein it is maintained by alternate coasting and driving by motor MM. The basket is then washed, after which a solenoid (not shown) in a control box 53 associated with a material supply tank 42 is energized, causing air to be admitted through line 49 to a cylinder 45, whereupon a gate 44 on a loading spout 43 is raised, box 53 is swung clockwise by a link 55 and a charge feeler 57 is swung towards the basket wall. Material from the tank 42 builds up against the basket wall, moving the feeler inwards and thereby causing partial closing of the gate through members 56, 58, 53, 55 and 46. Progressive closing continues until a limit switch LS is operated by a cam on shaft 59 to de-energise the solenoid in box 43 and thus completely close the gate. The feeler, loading mechanism and loading operation are as disclosed in Specification 717,899 [Group II]. The basket is now accelerated by motor MM operating first on a low-speed winding, and later on a high-speed winding, to full speed ; mother liquor is collected. The basket charge is then washed twice, the wash syrup where sugar is being processed being collected separately from the mother liquor, (" green liquor "), by the automatic shifting of a syrup separator. The charge is then dried by continued spinning at full speed. Thereafter the basket is decelerated and brought to rest, and then rotated slowly in the reverse direction by motor DM; during the latter rotation the discharger shoe (normally at the top of the basket) is swung outwards, traversed downwards along the basket wall, swung inwards and raised to normal position, the charge being expelled through opening 17a from which valve 26 was lifted while the basket was coming to a stop. Controls are provided for enabling one or more of all these steps to be effected independently. Assembly sequence controls. The initiation of the cycles of all the separators and their timing and individual duration are regulated by a group of timers, relays and switches which together comprise the assembly sequence controls and are incorporated in a circuit, Fig. 6 (not shown). When all the separators are empty and at rest and all are set to " re-cycle ", they may be started, at intervals governed by a pre-set assembly sequence timer, by a switch on the assembly sequence control panel, a selector switch being in the " independent re-cycling " position ; thereafter they continue to re-cycle indefinitely and independently. If the acceleration periods of the cycles of more than two of the separators begin to overlap, excessive drain on the power supply is prevented by the automatic closing of an overload contact, whereupon all the separators then in the coarse of a cycle continue to operate until their respective cycles are completed, after which they come to rest. Thereafter the assembly sequence timer restarts the separators in the same order and manner as before. This tendency to overlapping of the separator cycles can be avoided by turning the selector switch to " group sequencing " position, in which case the recycle timers of the individual separators are maintained subservient to the action of the assembly sequence timer. If the desired rate of production from the separators of the assembly is less than that obtained by operating them on normal cycles, and if also a longer cycle would render the solids too hard for discharge, the selector switch is turned to the " group sequencing "position, whereupon a further timer thereby brought into the circuit may be used to add a pre-selected idle time to the interval normally fixed by the assembly sequence timer between the starting times of any two successive separators in the assembly. The curb 27 may have a sliding cover coordinated with the operation of the loading gate as in Specification 774,955.