Approx. 2.6 Kgs of CO2 is released per liter by burning of engine oil. It is essential therefore to monitor and control lube oil consumption.
C I E M Solutions - Bhaskarudu Peddakotla, Consultant - Mining & Construction Machines
Lubricating oil plays a vital role in the health and efficiency of engines by preventing friction, acting as a cushion between moving parts, cooling by carrying heat, sealing between rings and liners for effective compression, and cleaning by carrying impurities. On the other hand, consumption of lubricants is a source of harmful emissions. Unburned or partially burned oil that comes through exhaust contains hydrocarbons and soot (particulate contamination). Further, engine oil anti-wear additives are known to poison or at least impair the performance of catalytic converters. The more oil consumed through the combustion chamber, the greater the poisoning risk. This escalates the environmental impact further. Approximately 2.6 Kgs of CO2 is released per liter by burning of engine oil. It is essential therefore to monitor and control lube oil consumption.
Factors causing excess oil consumption
Excess engine blow by: Certain amount of blow-by is unavoidable during piston movement inside the cylinder of the engine and is required. But the problem arises when it exceeds the limit. The common cause of excess blow by is the dust entry inside the engine which accelerates the wear of all the components of air intake system (turbocharger seals, bearings, valve seats, piston rings, liners, bearings etc). When the dust is passed through these parts, it mixes with the engine oil and forms a grinding paste, causing rapid wear of parts. This even leads to deposits in the piston ring grooves, causing rings to stick, leaving a huge gap between the rings and the liner, and thereby allowing the lubricant to pass into the combustion chamber and come out through the exhaust as a partially burnt product. Some amount of oil also comes out through the turbocharger seals and bearings. Other Issues like inadequate boost pressure, insufficient amount of air, overheating etc., are associated with dust entry in the intake air system. Hence, it is essential to maintain the air intake system properly by monitoring the condition of filter elements, clamps, joints, piping etc. It is also essential to have a dust suppression mechanism on the haul roads in construction sites.
Extended oil drain intervals: This is a common practice by people who want to save a few pennies, but the fact is that the oil drain interval is decided by considering factors like the application, average load factor, type and grade of lubricant etc. Hence, extending the oil drain interval will invite trouble. As oil ages, the effects of aging (high soot, loss of dispersing ability, additive depletion, insolubles, viscosity-index shear, dirt load, etc) impair the ability of the engine to retain the oil during service. Further, engine oil anti-wear additives are known to poison or at least impair the performance of catalytic converters. The more oil consumed through the combustion chamber, the greater this poisoning risk/effect, which escalates the adverse environmental impact further.
On the other hand, the majority of people follow predefined oil change intervals for all compartments of the machine. In fact hydraulic oils (which are higher in volume in majority construction machines) and gear oils need not be changed just as per predefined schedule, but those lubricants can be extended by monitoring oil condition periodically through proper oil sampling. By this overall consumption of lubricants and carbon emissions (emitted during crude processing and disposition of used oils) to that extent can be minimized considerably.
Excessive engine idling: There is a misconception that idle run of an engine is good for engine health, it minimizes fuel consumption etc, but the fact is that unnecessary idling not only wastes fuel but also causes air pollution and increased engine wear. An idling diesel engine produces higher emissions than it would while using the same amount of fuel under load. Every one liter burning of diesel releases 2.68 kgs of CO2. Excessive idling causes a build-up of soot inside the engine and results in a puff of black smoke, injectors dribbling, washing of liner and rings, engine oil dilution, lowering viscosity etc. The normal allowed idle time is 3 to 5 minutes, beyond which, it is to be considered as excessive idling.
