ClassNK (Nippon Kaiji Kyokai) has awarded its first Statement of Fact for Tier III nitrogen oxide (NOx) reductions to a marine diesel engine incorporating a Selective Catalytic Reduction (SCR) system. The document, issued November 1, 2011, verifies that emission measurement results for the engine, fitted with a pre-turbocharger SCR system developed by Hitachi Zosen Corporation, meet the NOx Tier III emission limits stipulated in amendments to Annex VI of the International Convention for the Prevention of Pollution from Ships 1973 (MARPOL).
The engine in question is installed in the MV SANTA VISTA a 37,800 dwt general cargo ship, built by shipbuilder Naikai Zosen Corporation for Nissho Shipping Co., Ltd., which entered service on 31 October 2011.
Not only is this the first time that ClassNK has issued such a document for a marine diesel engine fitted with an SCR system, it is also the first statement of fact issued by the classification society for Tier III NOx reduction compliance of any kind.
SCR systems offer the potential for independent reductions in emissions of more than the 80 percent required under Annex VI. Anticipating a growing interest in this technology and its applications in the near future, ClassNK has released new guidelines, Guideline for SCR (Selective Catalytic Reduction) Systems and Reductant Agent Supply Systems, to assist manufacturers, shipyards, and owners in installing such systems on their commercial vessels.
Hitachi Zosen says that the marine SCR system that it has developed is significantly different from conventional SCR systems. The system can be installed in front of the turbo charger of the engine instead of after it. Since it utilizes high-temperature exhaust gases discharged before they pass through the turbo charger, excessive CO2 is not emitted. And since the exhaust gas is still at a high pressure, gas density remains high and less catalysts are necessary so the entire system can be more compact.
December 30, 2011