Log in | Subscribe | RSS feed

What’s New

Conference report: 2013 CIMAC Congress

31 May 2013

The 27th CIMAC World Congress was held in Shanghai, China on May 13-16, 2013. The CIMAC Congress, organized once every three years, is a major technical meeting that covers internal combustion engine technology for ship propulsion, power generation and rail traction. About 260 papers were presented in Shanghai, in four parallel technical sessions and in poster sessions. The Congress also included an exhibition showcasing engines, engine components and related products, with strong participation from Asian suppliers. The meeting was attended by about 850 delegates.

Please log in to view the full version of this article (subscription required).

Two prominent focus areas during the Congress were (1) technologies for meeting the IMO Tier III emission requirements and (2) natural gas engines. Both the exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) technologies have been developed for NOx control from medium- and low-speed engines, including engines operated on residual, heavy fuel oil (HFO). In medium-speed four-stroke engines, Miller valve timing (together with two-stage turbocharging) is widely introduced to reduce NOx emissions and to increase engine efficiency. Natural gas provides another option for meeting Tier III NOx and SOx emissions, without the use of aftertreatment. With diesel fuels, the IMO SOx emission requirements will be met by using exhaust gas scrubbers, rather than by switching to low sulfur fuels. As desulfurization of HFO is not financially attractive and most fuel companies have no plans to supply residual fuels of reduced sulfur content, scrubbers provide the most cost-effective solution for ships, where fuel presents a major component of the total operating costs.

The choice of emission technology depends on the size of the vessel and the type of operation. Gas engines are predicted to be sustainable in some applications, for example in cruise ships running on MGO fuels [C. Wik, Paper #159]. In the case of an HFO fueled tanker spending most of its time in open sea, the best Tier III solutions must focus on fuel efficiency. With fuel costs amounting to 63% of the annual cost structure and the engine cost to only 1.3%, the preferred Tier III technology for a Panamax tanker is SCR aftertreatment combined with an exhaust scrubber.

It was apparent from the presented papers that all major engine manufacturers have invested into the development of Tier III emission systems. While some technical problems still need to be addressed (for example fouling of exhaust components by ammonium sulphates/nitrates from SCR systems or the purification of effluent dumped to the sea from scrubber systems to meet the applicable IMO standards), a number of systems appear to be ready for a commercial launch in 2016, as required by the current IMO standards. A potential postponement of the IMO Tier III requirements would not only delay the emission reductions from international shipping but would also endanger the business case for marine engine manufacturers and their emission system suppliers.

The interest in gas propulsion for ships is driven by the low cost of natural gas. At the current pricing levels, natural gas is about 50% less expensive than diesel distillate fuels and only about 10% more expensive than HFO fuels. One of the advocates of gas propulsion for ships is the Norway-based classification society DNV [C. Chryssakis, #265]. While predictions of future trends in natural gas pricing are highly speculative, there is a belief that the anticipated exports of LNG from the Unites States will put a downward pressure on gas prices.

Potential concerns with gas engines include increased GHG emissions due to methane emissions and/or leaks, as well as engine issues related to specific power, engine knock, safety, and fuel quality. There are no standards for methane number calculation and no bunkering standards for equipment and procedures have yet been developed. In case of fuel from cargo boil-off, the calorific value is decreased because of the nitrogen content, and high ethane content increases the risk of engine knock. These and other issues were analyzed by DNV, who evaluated the operational experience from 25 gas fueled vessels over a period of 2 years [T. Dirix, #158]. While some problems were identified, a large proportion of the gas vessels performed better than a reference group of diesel ships, and the study concluded that operating gas fueled engines is not more problematic than diesel fueled vessels. Gas engines have still lower power density than diesels (mainly due to self-ignition and knock), but manufacturers have a development objective to eventually achieve BMEP of 28-30 bar in gas engines, in line with that of diesel engines.

The next CIMAC Congress will be held in 2016 in Helsinki, Finland.

Conference website: cimac.com/congress_2013/congress_2013.htm