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Ctrifuge to clean disel crankcase oil
NEWS CENTRIFUGE
TO CLEAN DIESEL
CRANKCASE
OIL
Crankcase deposits can be formed in diesel engines if combustion products reach the sump due to piston blow-by and then mix with the lubrication oil. These sludges and emulsions can cause blocking of oilways and filters, and form deposits when they contact cold engine surfaces (eg push rods and rocker covers). Detergent or heavy duty oils have been introduced to reduce the formation of deposits. These oils usually contain additives which disperse the products of combustion by holding them in suspension. It is important that the impurities are removed from detergent oils so that they do not cause damage at points of close clearance in the engine. Pack type filters are unsuitable due to rapid sliming and choking of the packs. Absorptive bed type filters are equally unsatisfactory since ‘selective absorption’ on the filter bed can remove unused detergents. Sharples claim that their Super Centrifuge Gil Purifier will remove solid matters and moisture from contaminated sump oil. Although it is impossible to return the oil to its initial condition purification will remove the large harmful particles and make the oil suitable for blending with fresh oil for reuse. Sharples manufacture a range of centrifuges to cover all applications involving the separation of two immiscible liquids, and for removing solids from a liquid or mixture of liquids. The centrifuge is known as a clarifier when used to remove solid particles from a liquid to obtain a clarified liquid, and as a separator when used to separate two immiscible phases (ie an emulsion) into two separate liquids.
subjected to a uniform through the centrifuge. any sudden changes of tend to bring particles
centrifugal force while it passes As the liquid does not have to make . direction turbulent eddies, which would back into suspension, are avoided.
The rotor is suspended from the drive bearing assembly on a rubber mounted flexible spindle and its lower end runs in a loose fitting guide. This freedom of movement allows the centrifuge to rotate about its centre of mass, minimising unbalance and vibration and ensuring smooth operation.’ The drive of the centrifuge is above the level of the bowl‘so there is no danger of leakage into transmission parts, and it is also readily available for inspection and maintenance. Bowl cleaning and maintenance are very simple. The total time to stop the machine, remove the accumulated solids from the bowl and bring the machine up to speed again can be as low as 15 minutes, or if a spare bowl is used, 5 minutes. The general simplicity of design means that relatively unskilled labour can undertake any maintenance that is required. Sharples records show that the cost of maintaining a Super Centrifuge averages out at approximately 0.6% per annum of the value of the machine. To avoid high speed gearing, belt drive is used and it 1s claimed that any wearing part can be replaced in less than 20 minutes. The Sharples Division, Pennsalt Ltd, Tower Road, Camberley, Surrey, England
Works, Doman
Operation The centrifuge normally employed for cleaning crankcase oil is the Sharples No 6 which is verticle tubular bowl type (Fig 1). Particles smaller than 1 micron (0.00004in) will not be removed by centrifuging, but all particles larger than 2.5 microns (O.OOOlin) can be removed. The small particles that are left in the oil are non-abrasive and smaller than the thickness of the oil-film in the engine bearings but will give the oil a dark appearance. When used for detergent oils, the centrifuge is operated as a clarifier and the oil heated to 80°C (175”F), the heavy particles settle out on the rotor wall. With straight mineral oil water washing may be used to improve the purification. This should not be done with detergent oils as any water soluble additives could be removed. Also, some additives are efficient emulsifying agents and stable emulsions may be formed if water is added. The used oil is mixed with water in the ratio of 1: 1, and then about 2$% caustic soda is added. This mixture is then passed through the Super Centrifuge which is set up as a separator. The water phase containing most of the caustic soda and the water soluble impurities are then run to drain whilst the oil passes out as the light phase. To this oil phase wash water is added in the same proportion as above and the mixture passes through the Super Centrifuge using the separator bowl as before. The water phase is again run through drain. The separator bowl is then replaced by a clarifier bowl (or a clarified sleeve fitted to the separator bowl) and the oil passes through the Super Centrifuge once more. This removes any remaining solid particles that may be harmful, and produces a well purified oil which, however, would be dark owing to the colloidal carbon and sub-micron particles which remain in the oil. If it is required to remove these then a decolorising filter must be used. Features Sharples claim that their centrifuge generates a centrifugal force greater than 13,000 times the force of gravity, this gives a very high purifying effect. The liquid flows through the centrifuge bowl parallel to its axis of rotation and is
1 TRIBOLOGY
May 1969
63
TO CLEAN DIESEL
CRANKCASE
OIL
Crankcase deposits can be formed in diesel engines if combustion products reach the sump due to piston blow-by and then mix with the lubrication oil. These sludges and emulsions can cause blocking of oilways and filters, and form deposits when they contact cold engine surfaces (eg push rods and rocker covers). Detergent or heavy duty oils have been introduced to reduce the formation of deposits. These oils usually contain additives which disperse the products of combustion by holding them in suspension. It is important that the impurities are removed from detergent oils so that they do not cause damage at points of close clearance in the engine. Pack type filters are unsuitable due to rapid sliming and choking of the packs. Absorptive bed type filters are equally unsatisfactory since ‘selective absorption’ on the filter bed can remove unused detergents. Sharples claim that their Super Centrifuge Gil Purifier will remove solid matters and moisture from contaminated sump oil. Although it is impossible to return the oil to its initial condition purification will remove the large harmful particles and make the oil suitable for blending with fresh oil for reuse. Sharples manufacture a range of centrifuges to cover all applications involving the separation of two immiscible liquids, and for removing solids from a liquid or mixture of liquids. The centrifuge is known as a clarifier when used to remove solid particles from a liquid to obtain a clarified liquid, and as a separator when used to separate two immiscible phases (ie an emulsion) into two separate liquids.
subjected to a uniform through the centrifuge. any sudden changes of tend to bring particles
centrifugal force while it passes As the liquid does not have to make . direction turbulent eddies, which would back into suspension, are avoided.
The rotor is suspended from the drive bearing assembly on a rubber mounted flexible spindle and its lower end runs in a loose fitting guide. This freedom of movement allows the centrifuge to rotate about its centre of mass, minimising unbalance and vibration and ensuring smooth operation.’ The drive of the centrifuge is above the level of the bowl‘so there is no danger of leakage into transmission parts, and it is also readily available for inspection and maintenance. Bowl cleaning and maintenance are very simple. The total time to stop the machine, remove the accumulated solids from the bowl and bring the machine up to speed again can be as low as 15 minutes, or if a spare bowl is used, 5 minutes. The general simplicity of design means that relatively unskilled labour can undertake any maintenance that is required. Sharples records show that the cost of maintaining a Super Centrifuge averages out at approximately 0.6% per annum of the value of the machine. To avoid high speed gearing, belt drive is used and it 1s claimed that any wearing part can be replaced in less than 20 minutes. The Sharples Division, Pennsalt Ltd, Tower Road, Camberley, Surrey, England
Works, Doman
Operation The centrifuge normally employed for cleaning crankcase oil is the Sharples No 6 which is verticle tubular bowl type (Fig 1). Particles smaller than 1 micron (0.00004in) will not be removed by centrifuging, but all particles larger than 2.5 microns (O.OOOlin) can be removed. The small particles that are left in the oil are non-abrasive and smaller than the thickness of the oil-film in the engine bearings but will give the oil a dark appearance. When used for detergent oils, the centrifuge is operated as a clarifier and the oil heated to 80°C (175”F), the heavy particles settle out on the rotor wall. With straight mineral oil water washing may be used to improve the purification. This should not be done with detergent oils as any water soluble additives could be removed. Also, some additives are efficient emulsifying agents and stable emulsions may be formed if water is added. The used oil is mixed with water in the ratio of 1: 1, and then about 2$% caustic soda is added. This mixture is then passed through the Super Centrifuge which is set up as a separator. The water phase containing most of the caustic soda and the water soluble impurities are then run to drain whilst the oil passes out as the light phase. To this oil phase wash water is added in the same proportion as above and the mixture passes through the Super Centrifuge using the separator bowl as before. The water phase is again run through drain. The separator bowl is then replaced by a clarifier bowl (or a clarified sleeve fitted to the separator bowl) and the oil passes through the Super Centrifuge once more. This removes any remaining solid particles that may be harmful, and produces a well purified oil which, however, would be dark owing to the colloidal carbon and sub-micron particles which remain in the oil. If it is required to remove these then a decolorising filter must be used. Features Sharples claim that their centrifuge generates a centrifugal force greater than 13,000 times the force of gravity, this gives a very high purifying effect. The liquid flows through the centrifuge bowl parallel to its axis of rotation and is
1 TRIBOLOGY
May 1969
63