Nippon Yusen Kabushiki Kaisha (NYK Line), Oshima Shipbuilding, Mitsubishi Heavy Industries, Akasaka Diesels and Sakai Chemical Industry Co. are to begin shipboard tests of selective catalytic reduction (SCR) nitrogen oxide (NOx) removal equipment installed on NYK Line's new bulk coal carrier 'Initial Salute', which was built by Oshima Shipbuilding.
Shipboard trials of SCR NOx removal equipment were conducted during the voyage of 'Initial Salute'. Once the equipment was verified to meet the tier III NOx emission controls stipulated by the International Maritime Organisation (IMO), it was decided to leave the equipment in place to collect more data through tests to be conducted during actual operational voyages. The installation of SCR NOx removal equipment after turbocharging, on board 'Initial Salute' is the world's first trial on a low-speed marine diesel engine.
The new SCR NOx removal equipment will meet the tier III NOx emission control requirement by further reducing emissions while maintaining the superior combustion efficiency that is the main feature of a low-speed marine diesel engine.
The group initially thought that SCR NOx removal equipment would find it difficult to respond to future NOx emission controls because in an atmosphere of low-temperature exhaust gases below 300°C, ammonium hydrogen sulfate (acid ammonium sulfate) — generated by the chemical reaction of the sulfur in fuel oil with the ammonia in the reducing agent — poisons catalysts. However, the new SCR NOx removal equipment has been improved to reduce catalyst poisoning to a minimum level by suppressing the sulfur in fuel oil to approximately 0.1 percent. As a result, in an atmosphere of low-temperature exhaust gases at 250°C after turbocharging, stable denitration effects were observed during a test on land, which led to shipboard tests on an operational vessel with an eye to practical use.