Effective filtration cuts costs and optimises efficiency

In today’s increasingly competitive global market, vessel operators are under incredible pressure not only to protect operating margins, through cost efficiencies, but also to comply with ever more rigorous environmental legislation. For many vessels, running and maintaining diesel engines represents a significant proportion of overall ownership costs; combine this with rising fuel prices and an increasing raft of tough emissions legislation, it seems certain that these costs will continue to grow.

In part, however, these costs can be controlled through the use of effective filtration systems, designed to be used in fuel lines and as part of closed crankcase ventilation (CCV) units. In particular, there is increasing focus on reducing crankcase emissions in order to limit the amount of environmentally harmful hydrocarbons (HC), nitrogen oxide (NO_x) and particle matter (PM) and to ensure compliance with current regulations. At least as far as smaller four-stroke engines, as used in auxiliary applications on large ships as well as main propulsion for smaller vessels, are concerned, crankcase blow-by gases are the second biggest emitter of pollutants. On conventional open crankcase engines, a combination of unburned fuel and exhaust gases, mixed with oil aerosol, soot particles and displaced air, is released into the atmosphere.

To avoid these problems, leading manufacturers, such as Parker Hannifin, have introduced a new generation of ultra high efficiency -10 grade media closed crankcase ventilation (CCV) systems that filter the blow-by gases simply and effectively. Parker’s CCV12000, for example, is suitable for 2000hp engines with a single unit, which the company says offers a 93% efficiency rate from a retrofitable media solution.

In some applications vessel operators have found it possible to switch to bio-fuels, including 100% biodiesel, derived from vegetable oils or biomass. In addition to the environmental credentials, these fuels can provide additional advantages, including taxation benefits and the ability to sell the spent rapeseed. However, they introduce a number of challenges.

For instance, some carbon neutral fuels and ultra low sulphur diesels (ULSD) have been shown to pose a number of problems to conventional engines and filters. When run on certain biofuels, the fuel filters in a vessel’s diesel engine can quickly become clogged with particulates, especially in cold conditions to which many ships are subject.

This is due to the lowering effect that both biodiesel and ULSD can have on the cold filter plugging point (CFPP) of fuel. This can lead to reduced engine performance, and in the worst cases, a complete break down, as wax crystals form and clog fuel lines and filters. In addition to contributing to contamination issues, biodiesels typically react chemically and attack rubber sealing components in the fuel system. This can be overcome with regular servicing and the use of sealing components manufactured from alternative fluro-elastomer materials.

Unfortunately, other problems associated with biodiesels are not so easy to avoid. The properties of the fuel, and the way in which it is refined, mean that it typically contains a high level of particulate matter, especially in the 10-20µm size range – the most damaging to fuel injectors and injection systems. The chemical and thermal instability of the fuel can also increase still further particulate contamination, agglomerates, varnishes and oxides in the fuel tanks, leading to increased maintenance requirements and reduced service life of components.

The latest fuel filtration technology has been applied to enable manufacturers and end users to overcome the problems posed by biofuels. According to Parker, these modern filters incorporate innovative features such as special seal materials, improved filter media and positive temperature coefficient (PTC) heaters, which allow each filter to warm the fuel before filtering it, tackling the potential problems of operating in low ambient temperature conditions, such as coagulation.

Due to the filters’ ability to warm the fuel before filtering and the fine levels of filtration that they are capable of, they can increase cleanliness of the fuel flowing through to the injectors and engine by up to a factor of 100 in some cases. This translates to considerably longer service lives for components, reduced maintenance requirements, and ultimately lower costs.

The growing awareness of the causes of climate change is putting increasing pressure on vessel operators to adopt environmentally responsible practices, such as reducing crankcase emissions or switching to eco-friendly renewable fuels. With the filtration technology now available, it is now possible to do this simply and cost effectively, enabling compliance with ever stringent emissions regulations. Just as importantly, says the company, these latest filtration systems represent an opportunity for vessel operators to increase significantly the performance and efficiency of engines, which ultimately allows them to realise considerable reductions in both costs and downtime.