GB703880A - Improvements in and relating to fluid supply systems - Google Patents

Abstract

703,880. Filter supply systems. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 22, 1951 [Oct. 26, 1950], No. 24585/51. Class 46 In a fuel supply system. such as for a gas turbine in a locomotive, one of a pair of filters 3, 4 is arranged in the supply line and a device 29 is provided which is responsive to a predstermined fluid pressure drop across the filfer due to accumulation of foreign matter thereon for starting a control cycle in which the filfer in use is disconnected from the supply line, the second filter is connected in the line and the first filter is cleaned. As shown the fuel oil passes from tank 1 through three-way cock 21, line 16, valve 17, and inlet 13 to filter 3, which may be of the type described in Specification 674,915; the filtered oil passing from outlet 8 through check valve 71, differential pressure responsive switch 29 and check valve 28 to the supply line 2. Since the switch 29 is connected by line 75 and check valve 78 to the filter inlet 13, when the differential pressure across the filter reaches a certain value switch 29 closes an electrical circuit which starts a motor 25, a time delay switch being incorporated in the circuit to obviate false operation by momentary pressure variations. The motor 25 rotates a shaft carrying a series of cams one of which, 45, operates a switch 90 to ensure a half revolution of the shaft, and also closes steam line drain valve 44. Next cam 24 partly opens valve 18 allowing filter 4 to fill with fuel through line 16 and inlet 13, further rotation of cam 24 fully opening valve 18 and closing valve 17. Fuel oil now passes through filter 4, outlet 8, line 27, and check valve 72 to the supply line 2. Then the main steam valve 40 is opened by cam 41 and the fuel oil drain valve 62 of filter 3 opened by cam 64 to allow the oil to drain from filter 3 through drain 14, line 60, valve 62 and drain line 43 back to the tank 1. Later two nozzle chest valves 48, 53, are opened by cams 50, 55 to force oil from the filter 3 to the drain line 60 by means of steam which coming from a supply line 30 passes through a main manually controlled valve 31, valve 40, line 39, check valve 42, valves 48, 53 and lines 51, 46, having check valves 56, 57, to a steam chest 10, provided with a series of nozzles similar to those shown at 9, in filter 4. Next valves 48, 53 and the fuel drain valve 62 are closed. Then blowdown valve 67 is opened by cam 69 to allow sludge from filter 3 to be blown through lines 65, 73, into a tank (not shown). Nozzle chest valve 48 is then opened to allow steam to impinge through the nozzles on to one side of the filter elements, the latter being meanwhile rotated through gearing 70 actuated by motor 25. The valve 48 is closed and simultaneously valve 53 is opened allowing steam to impinge on the other side of the filter elements. Later valve 53 is closed and the main steam valve 40 and blow down valve 67 also closed. The steam line drain valve 44 is then opened and finally switch 90 is opened to break the motor circuit and end the cycle. When filter 4 becomes congested switch 29 will again close and the cycle of events is repeated, the oil once more being filtered through filter 3 whilst filter 4 is cleaned. The filters are heated by steam coils 32, 33, connected to the steam line 30 through lines 34, 35, and valve 36, the condensate being discharged through line 37. The motor 25 may be started at any time by manual operation of a push button and a pair of switches, one for each cab allow automatic operation to the cut out when desired, a pair of warning lights indicating when this has been done.