Patent GB-607638-A (GB)
Title: Method and apparatus for purifying oils
IPC: F02B3/06
Filed: 1946-02-06
Abstract: <PICT:0607638/III/1> Oils containing sludge and/or water, particularly lubricating oils in large machinery plants or prime movers equipped with lubrication systems of the oil circulation type, are purified by passing the oil through a separate circulation circuit disposed between an oil purifier and an oil supply, said circulation circuit comprising an oil heating device and a pump, said pump being arranged to supply oil to the circulation circuit through an inlet connecting the oil supply to the circulation circuit, to discharge oil from the circulation circuit through an outlet connecting the circulation circuit to the oil purifier, and also to cause part or all of the oil to circulate in the circulation circuit for a suitable length of time prior to being discharged to the oil purifier.  In the illustrated example of the invention the gear pump 10 driven at constant speed from the centrifugal separator 23 draws the lubricating oil to be purified from the lower level chamber 1 (e.g. the oil sump or crank-case base-chamber of a Diesel engine) via suction pipe 4, control valve 5, liquid seal 8 and suction pipe 9 into a circuit including a heater 11 and de-aerator 12.  The heater 11 is preferably thermostatically controlled.  The major portion of the oil entering the de-aerator 12 returns to the suction pipe 9 via the control valve or throttling device 14, so that a comparatively high rate of flow is maintained in the heater, whereby the separating out of water and/or the burning on of sludge deposits in same are prevented, and at the same time a good heat transmission is obtained. A minor proportion of the quantity of oil passing through the heater 11 and de-aerator 12 per unit of time is normally led to the purifier 23 via the control valve 20 and outlet pipe 18.  The purified oil discharged from the separator returns via gear pump 26, and pipes 28 and 30 to the engine sump 1, while the water discharged from the separator is led away by the waste pipe 32.  In the event of the pump 10 being stopped and control valve 5 being open, the oil flows back through the feed pipe 4 from the circulation circuit to the oil chamber 1, but the circulation circuit may be so constructed and arranged that at least a certain minimum quantity of oil, necessary to re-establish the oil circulation when the pump is re-started, is retained therein.  To this end, for example, the level of the heater 11 is located below that of the junction of the pipes 4 and 9, and, if necessary, the capacity of the pipe 9 is increased by the installation of an oil tank 15.  In this manner, when the pump 10 stops, sufficient oil is retained in the portion of the circulation circuit between the junction of the pipes 4 and 9 and the suction side of the pump, that the portion of that oil which at the re-starting of the pump is transmitted to the pressure side of the pump, is sufficient partly to replenish the emptied part of the circulation circuit on the pressure side of the pump as far as the de-aerator 12 and partly to create in the latter the liquid seal required in order that the oil feed to the circulation circuit through the inlet pipe 4 shall be re-established by the sucking action of the pump.  The circulation circuit may also be so constructed and arranged that in the event of valve 14 being closed when the pump 10 is stopped, and the entire circulation circuit, excepting the de-aerator 12 thereby emptied due to the section action in the oil column 4, the volume of oil retained in the de-aerator is sufficient to replenish the emptied portion of the circulation circuit on the pressure side of the pump as far as the de-aerator when the pump is restarted and valve 14 re-opened. Sufficient oil must also be retained in the de-aerator to form a liquid seal therein in order to prevent air from passing from the de-aerator to the suction side of the pump and thus preventing the re-establishment of the oil feed to the circulation circuit from the inlet pipe 4.  The junction of pipes 4 and 9 may be higher than or at the same level as the pump 10 and also higher than the heater 11 and may be so arranged that the oil stream in the feed pipe 4 joins that coming from the de-aerator 12 in such a manner, for example, at right angles, that the oil streams do not seriously disturb one another at the point of confluence.  The inlet may also be provided with a device, such as a threshold, rendering difficult the escape of the oil returning from the de-aerator through the inlet.