Method of Filtration of Impure Oil Using Streamline Filter
Q. With the help of neat figure explain the method of fitration of impure oil using streamline filter (vacuum type).
Stream Line Filter (Vacuum Type) :
Main part are :
- Oil-inlet pipe
- Heating chamber
- Heaters
- Purifier chamber
- Filter packs
- Vacuum tank
- Motor
- Pump
- Pure oil outlet
- Sludge outlet
Filtering process:
Through inlet pipe
(1) the impure oil is taken in the heating chamber
(2) In this chamber heater units
(3) are provided by which the oil is heated to a temperature of 60° to 75º C. The advantage heating is to make the oil thinner which facilitates separation of impurities moreover it release dissolved gases and moisture. This hot oil is pumped into the purifier chamber
(4) In this chamber the oil is pressed under a high pressure (See pressure tank pressure gauge and air pipe in the figure). The pressure is about 6 kg / cm2. Oil then passes through several stocks of specially prepared thin paper disc which are kept tightly packed and compressed by powerful springs.
(5) The interfaces between the surfaces of the filter paper are so fine that even microscopic impurities cannot pass through. All such impurities are accumulated on the outer surfaces of the fitter picks. The purified oil is withdrawn from the central hole in the paper stack through which the holding down bolt passes. This operation is continued for some time. During this period sufficient amount of sediments, dust, dirt etc. is collected on the outer surface of filter pack Compressed air is admitted in the central hole of the pack by operating the valve. Compressed air forces out and releases deposited sediments dust and carbon deposits and all the dirt oil , sludge and water are ejected out of the drain pipe Process is restarted after flushing out the dirty oil from the chamber. The purified oil from the purifier enters the vacuum tank
(6) Here it is dropped into the open trays. The oil is thus exposed to dehydrating vacuum is maintained by electrically driven high vacuum pump
The reduction of atmospheric pressure above liquid surface lowers its boiling point. Moisture contained in oil is, therefore quickly liberated under reduced pressure. Hence, exposure to vacuum the last traces of dissolved moisture air gas are removed, the oil becomes perfectly dry with his electric strength. A float valve is provided in the tank outlet below the vacuum pipe is collected purified oil outlet pipe, is refused for transformers etc.