The other side of the coin.

Emulsion offered as an alternative to injection .

MAN B&W has tested direct water injection but has opted to go down the emulsified fuel route to reduce emissions. “Of course we see, as expected, the NOx reductions with water injection. But we see the fuel increase in connection with nearly all kinds of NOx reduction,” says Niels Kjerntrup, senior manager in the process development department at MAN B&W Diesel A/S. He explain: “We see a negative crossover with fuel consumption ? lower NOx gives higher fuel consumption ? that is the general tendency. It is the same for water emulsified fuel but the technology is much cheaper and it is this that has made MAN B&W opt to continue its development to commercial status for water emulsified fuel.”

The company?s ME engine gives it complete freedom to model injection patterns on the electronic controlled engine making it very suitable for operating with emulsified fuel. “Because there are very small changes required on the engine in order to go from standard fuel to water emulsified fuel and, at the same time, we can optimise the injection pattern just by the ME principles without making any further additions to the engine,” explains Kjerntrup.

He believes that, had the company opted for water or steam injection into the cylinder other than in the fuel, it would had to be done together with some other process improvement. He told The Motor Ship: “That means we should use it for modelling the compression curve of the engine ? it should have another purpose than just NOx reduction, which has been in focus up until now.”

Running emulsified fuel on a standard mechanical engine requires modifications to the camshaft and the fuel pump but on a ME engine using electronic control only the atomisers have to be changed. Kjerntrup says: “Of course, you should be able to supply more power to your hydraulic system because you have a bigger volume flow of fuel but that is the only modification that you have to do on the ME engine and at the same time you have the opportunity to modulate the fuel injection pattern with the ME principles.” Although this was not the main purpose of the ME development it was thought about at the time.

Short term development

Kjerntrup describes the work being done by MAN B&W on combining the use of water emulsified fuel on the ME engine as “our short term development”. But there are a lot of other issues regarding emission reductions such as scavenging air moisturing, he says. “Here we are far on in the process of making the first prototype application with scavenging air moisturing ? we are making a scale test in service with the first version of our SAM system.”

He told The Motor Ship: “The water emulsified fuel is the standard and can be implemented freely if wanted ? the SAM system will also be very close to a commercial stage in a year or so from now ? we need to do the service testing and then we will be ready to have this as an option also and we are working with exhaust gas re-circulation. Everybody knows water is working and exhaust gas recirculating is working when we are talking about emissions reduction ? that basically means NOx reduction of course taking into consideration that we don?t have particulate emissions increase in this combination.”

MAN B&W is following developments on steam water injection but is concentrating its efforts on the three technologies mentioned. “The three other issues are of higher priority in our development than direct water injection or direct steam injection,” says Kjerntrup.

The water emulsified fuel is extremely cheap to apply and, although the company hasn?t fixed a price yet for its SAM system. “It will be relatively cheap because we of course have some add-ons with SAM but we also have some possibility for removing the scavenging air cooler and other parts,” concludes Kjerntrup.