World’s first SCR NOx removal system installed on bulker

22 Jun 2011
Diagram showing the SCR NOx removal system

Diagram showing the SCR NOx removal system

NYK Line, Oshima Shipbuilding, Mitsubishi Heavy Industries, Akasaka Diesels and Sakai Chemical Industry are to begin shipboard tests of selective catalytic reduction (SCR) nitrogen oxide (NOx) removal equipment.

Initial shipboard trials of SCR NOx removal equipment were conducted during the voyage of NYK Line’s new bulk carrier, the 88,500dwt Initial Salute, built by Oshima Shipbuilding. Once the equipment was verified to meet the tier 3 NOx emission controls stipulated by the 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 first trial on a low-speed marine diesel engine. The equipment will meet the tier 3 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.

It was 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 sulphate, generated by the chemical reaction of the sulphur in fuel oil with the ammonia in the reducing agent, poisons catalysts. However, the equipment has been improved to reduce catalyst poisoning to a minimum level by suppressing the sulphur in fuel oil to about 0.1%. 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.

Given the heightened awareness of environmental issues, NYK Line is proactively involving itself in reducing the environmental impact caused by its vessels. Oshima Shipyard, MHI, Akasaka Diesels and Sakai Chemical have initiated, as a high-priority issue, R&D that focuses on future environmental regulations to be imposed on vessels. Since 2007, these companies have participated in the ‘R&D on super clean marine diesels’ initiative, which is subsidised by The Nippon Foundation, and conducted by the Japan Marine Equipment Association under the leadership of the Ministry of Land, Infrastructure, Transport and Tourism.

In addition, since 2010 the companies have been involved in developing technology for a denitration system that will work with low-temperature exhaust gases of low-speed marine diesel engines, including shipboard tests, with technical cooperation from the National Marine Research Institute. Against this background, NYK Line decided to cooperate in this research with the trial instalment of SCR equipment on its own operating coal carrier.

The five companies will continue R&D activities related to the environmental field so as to contribute to the reduction of the environmental impact of the global marine industry.

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