World’s First SCR NOx Removal System.

By Keith Henderson at June 23, 2011 08:05
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Completed in March of this year by the Oshima Shipbuilding Co., Ltd., Japan, the double hull bulk coal carrier MV Initial Salute is the first ship in service fitted with selective catalytic reduction of nitrogen oxides removal equipment. The 88,100 dwt ship has an LOA of 770 ft (235 m), beam 140 ft (43 m) and draft of 62 ft (19 m). Powered by a single slow speed, two stroke, MHI 6UEC60LSII rated at 11,000 kW at 105 rpm, her maximum trial speed was 16.2 kn with a normal cruising speed of 15 kn.

The tests are being carried out with a financial contribution of the Ministry of Land, Infrastructure and Transport, together with the cooperation of the National Maritime Research Institute, Akasaka Diesels Limited, Sakai Chemical Industry Co., Ltd, NYK Line and Oshima Shipbuilding Co., Ltd.

The low-temperature exhaust gases below 570 degF (300 degC) produced by a slow speed two stroke engine were feared to cause ammonium hydrogen sulfate (acid ammonium sulfate) to be generated by the chemical reaction between sulfur in the fuel oil and ammonia in the urea reducing agent, thereby contaminating the catalysts. Consequently the efficiency of the SCR NOx removal equipment was in doubt and there was concern that this system might not be capable of delivering the NOx reductions required by future emission regulations.

Improvements made to the equipment reduced the catalyst poisoning to a minimum level by suppressing the sulfur in fuel oil to approximately 0.1 percent.

Following encouraging results of tests ashore, in an atmosphere of low-temperature exhaust gases at approximately 480 degF (250 deg C) exiting the turbocharger, stable denitration effects were observed which suggested tests on board ship on an operational vessel could produce practical benefits.

The on board tests produced results that meet Tier III NOx emission controls stipulated by the International Maritime Organization (IMO). The results were so successful that it has been decided to extend the tests and collect more data over a longer period during normal operational service.

 


Caption: Diagram of the SCR NOx removal system
Image credit Akasaka Diesel Ltd

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