Based on an article submitted by Bill Wen Chang Huang, Taiwan

Wärtsilä is ready for steam injection, particularly when energy prices rise.

Since the end of the EU-funded STID (STeam Injected Diesel engine) project to develop and test a new combined diesel and steam process, which finished last year, Wärtsilä has been working in-house to evaluate whether the means can be found to find all the heat required from the engine.

The technology is not really today?s technology but tomorrow?s and is very dependent on energy prices rising by between 150 and 200%. Daniel Paro, Senior Vice President of Wärtsilä, told The Motor Ship: “Personally, I think a company like ours should develop things for the future even if they are not absolutely feasible because you have to calculate different scenarios for low, medium, high or very high energy prices.” He says that although the steam injected diesel fits into the high to very high energy price scenario it probably won?t be too long before the technology is needed. “But, in today?s harsh Wall Street climate for companies, that is not how people normally think and neither do we,” he explains. Companies think of today?s profits rather than profits in 20 years time or so. “This has been done as a safeguard so that we know we have something in our back pocket,” says Paro.

If energy prices do rise by one and a half to two times what they are today then it would spark the development of things like steam injection. This is because, although there is no doubt that the installation will be 35% to 50% more expensive than today?s installation, you are likely to get back a 10% improvement in fuel consumption, which, if you calculate the payback time, you find that it is three, four or five years, according to Paro. Although that is not acceptable in today?s situation it might be if the energy price goes up ? as it shortens the payback period ? and a general increase in energy price will also boost all kinds of taxes on energy to push down consumption.

Fuel efficiency

Paro says Wärtsilä has reached more than a 25g/kWh improvement in fuel efficiency, of which at least 15 is possible. After 15 ? at least with the current set up ? it starts to deteriorate other important parameters such as increasing smoke opacity and an increase in CO and unburnt hydrocarbons in the exhaust gases. But up to 15g/kWh there are basically no negative effects, explains Paro.

With additional work he believes that 20g/kWh is possible, which is then more than 10% improvement in fuel consumption. He told The Motor Ship: “This is likely to come from further improvements to the combustion chamber and the injection process. Now we inject the steam into the combustion space, which is optimised for pure fuel injection and it could be that the piston shape needs to be different. We really don?t want the maximum mix of the steam into the air. We want to have a minimum mix of the steam into the air because emissions are not the main driver but efficiency.”

Technically it will work and further improvements on 15g/kwh may be possible but not with today?s energy prices. Paro explains that the extra costs are only for hardware additions and does not cover the development costs. “My guess is that it is between 30-50% more expensive per kW to install such a device ? and when you go further you might find that you need totally different materials inside.”

Wärtsilä are not currently running hardware tests ? it has taken a break and is making careful analysis of the heat balance of an engine and is trying to figure out how exactly it can be optimised. “You can pick heat in different sequences ? you take something before the turbocharger, something after the turbocharger etc and that is a detailed job where you need to make a lot of simulations and re-runs and that is the next stage, although it has not started yet,” explains Paro. “Then, when we know that we will put it on the shelf and wait for the energy price to increase.”

He concludes: “The steam-injected diesel has a good chance of happening sometime, but whether it is within the next ten years or 100 years is difficult to say. However, the company says it is more than ready.”