In an ever-changing world of increased demands for higher uptime, lower emissions and faster response, finding new solutions and staying ahead of the times is the only way forward. One example of this is the high-speed tugboat Xia Gang Tuo 21, which operates in the Port of Xiamen, China, where everything is bigger, and the work never stops.
The marine-specific solution designed by Caterpillar includes Selective Catalyst Reduction (SCR) technology to meet Tier 4 Final emission standards with few or no changes from the Tier 4 Interim solution. SCR has less impact on engine efficiency and durability than other emissions reduction solutions such as EGR. The new Tier 4 Final solution offers superior performance and an increase in power. Since SCR only impacts emissions there is no alteration to core engine components, no increase in the injector, the cylinder pressure or in heat rejection.
It offers total reliability with maximum uptime in the most demanding applications without interruption, and supreme durability with the same long life to overhaul. Installation flexibility brings minimum impact to the vessel design owing to different configurations with multiple mounting options and a multi-position spool piece. As well as reduced emissions, SCR offers improved fuel efficiency, which translates to lower owning and operating costs.
THE 1-2-3 OF SCR
The dosing cabinet mixes the right dosage of compressed air [1A] and urea [1B] drawn from the the urea tank and transfers it [2A] to the SCR module where it is injected into the exhaust stream [2B] . In the SCR module [3] water evaporates and the urea is converted into NH3. When ammonia comes in contact with the SCR catalyst there is a reduction in NOx. The final output is carbon dioxide, nitrogen, water and oxygen.
