Gudbjartur Einarsson, marine engineer:
Do you want to economize and help nature too?
It may be asserted with valid arguments that there is a correlation between the abnormal use of lube oil, amounting to millions of liters per year, and over-pressure in the crankcase.
Recent years we have seen an increase in the use of lube oil in new and older diesel engines.
Many people say that there is a correlation between the increased use of lube oil and an increase in the use of new types of fuel oil.
Engine manufacturers state that their diesel engine burn from 0,6 – 1 gr/hph, whereas a large number of marine engines in fact consume manifold this quantity. This guidelines have excisted for many years and have long since become obsulete when taking into consideration the environmental regulations that become more stringent every year.
Engine manufacturers have taken this development seriously and have changed both the pistons and the piston rings in order to reduce the lub oil consumption. In many instances very positive results have been achieved.
Many marine engineers have been of the firm opinion that engines need to burn lube oil in order to facilitate a normal renewal of the oil. This is a major misunderstanding because a large portion of the lube oil travels as soot or unburned through the ship´s smokestack, polluting both the air and the sea. From an environmental point of view, the best would be if the engine would not burn the lib oil. If this situation were to emerge, which is unlikely, it would be more sensible to pump a certain quantity of oil from the engine daily, i.e., if people were prepared to take such a step.
There are, however, other causes for the lube oil consuming greatly exceeding the “normal” burning level as stipulated by the engine manufacturers:
Lube oil leakage.
· High pressure in the crankcase.
Lube oil leakage is very common, particularly in older engines. This can become a major problem, even though it is frequently difficult for the marine engineer to realise the extent of the leakage when he sees a drop here and there.According to a Danish study, one drop of oil per second constitutes 200 liters per month, steady leakage 2.700 liters per month; hence in in one year this is certainly a large quantity of oil.
Over the last ten years, many engine manufacturers have realized that over-pressure in the crankcase has many negative consequences, including increased pressure on joints and gaskets, which results in leakage and dangerous pollution in the engine room, which may in the future lead to claims from seamen because of health damage. Over-pressure also creates internal oil-leakage. The lub-oil is forced up along the pistons and into the compression room, and mainly goes as soot or unburned into the atmosphere.
Engine manufacturers like Detroit Diesel, Cummins, CAT, Deutz etc. have in the last 8-10 years dealt firmly with this issue, as well as focusing on other environmental issues regarding their engines. They have installed special separators (closed-circuit system, vacuum controlled) in the turbine with the crancase ventilation pipe beeing connected to the separator. This method creates under-pressure in the crankcase and thereby reduces the lube-oil consumption by as much as 30%.
The old method of leading the ventilation pipe from the crankcase directly into the atmosphere is not desirable from an environmental point of view, and fortunately, engine manufacturers are increasingly abandoning this method. Additionally, this method will be dropped in the future because of the increasingly stringent demands on environmental protection.
It may be mentioned as an example that in the future the ventilation pipes og the tanks of oiltankers and ships receiving oil (North Sea) must have oil/gas separators for pullotion prevention purposes.
The owners of older and new engines are also increasingly using the aforementioned separator system with good results. An example of this is a shrimp trawler from the Faroe Islands. The trawler has a 1.800 hp Alpha main engine. The high level of lub-oil consumption was a problem, i.e., the engine consumed 95 liters per day, because of much lube-oil leakage in seals and joints, and led to dangerous pollution in the engine room, glazing occured in the cylinder covers and there was much over -pressure in the crankcase. When the separator system had been installed, the engine´s lube-oil consumption dropped to 50 litres per day ( a decrease of 15.000 liters per year), the pollution in the engine room disappeared and there was under-pressure in crankcase.
Two months later the engine was overhauled, the cylinder covers were honed and another type of lub-oil was used in the engine. This resulted in the oil consumption decreasing dramatically,i.e., it was 22 litres per day (a decrease of 22.000 litres per year) and has remained unchanged.
It is fair to state that honing of the cylinder covers played an important role here because of less air pressure down along the pistons and because of under-pressure in crankcase, which decrease the flow of lub oil up along pistons.
This example and hundred of similiar instances provides grounds in support of there being correlation between abnormal use of lub-oil, amounting to millions of litres per year, and over-pressure in the crankcase.
Researches states that a chemical analysis of the glazing in the cylinder covers indentified calcium hydroide, which is found in most types of lub oil, but not in fuel oil. Hence, it is very likely that much flow of lub oil in the compression room creates a risk of cylinder glazing which through a chain reaction, results in increased pressure in the crankcase and more lube oil consumption.
More stringent environmental regulations for ships are something we must prepare for over the nest few years.
Many countries are now strengthening their regulations regarding internal and external pollution from ships.
The Icelandic parliament, Althingi, passed a parliamentary resolution on March 11. 1999, calling on the government to take measures to improve workplace protection and pollution prevention among seamen.
The International Maritime Organisation (IMO) is announcing various more stringent measures against the external pollution from ships. The International Transport Federation (ITF) has made it a priority project over the next few years on the international scene to work towards improved pollution prevention regulations for seamen. These are just a few examples of the measures that are now beeing taken.
More stringent regulations in these areas are very positive. In the future, they will help to improve the image of shipowners and strengthen their market position. For instance are fishing vessels in fact equipment used for handling food that is sold at vunerable markets. The buyers and consumers will increasingly consider weather the food is produced and transported in environmentally friendly circumstances in respect of the employees and the physical arrangement at the production site. Various foreign researches reveals that improved environmental circumstances at sea and on land can save money for business and society in terms of expenditures to health and environmental affairs.
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