Marine Selective Catalytic Reduction (SCR) Retrofit Aftertreatment Caterpillar

Aftertreatment Component Storage

Normal periods of inactivity will not require special attention to the SCR system. The SCR is designed to begin and end operation with the output of the power system the SCR is assembled to. Extended periods of inactivity or product storage will require preventative maintenance preparations up to, and including:

• Purging the emission reduction system.

• Shutting off the system prior to storage.

• Cover or plug all inlet and outlet fittings.

• Cover any exposed electrical connection fittings.

• Protect the dosing cabinet from inclement weather.

• Prevent water from entering the CEM.

Sea Water or salt spray may cause exposed stainless steel surfaces on the CEM and other hardware to corrode. Care should be taken to avoid contact with salt water while in storage. Slight surface corrosion is normal and will not impact the performance of the CEM.

Diesel Exhaust Fluid (DEF) Circulation System

• Disconnect electrical service to the DEF supply/circulation system if applicable.

• Close all ball or gate valves within the circulation loop.

• Shut off all ball valves to the dosing cabinets.

• Close off ball or gate valves coming from the DEF (Urea) holding tank.

The bulk urea tank and urea supply system are designed and supplied by the shipyard, the following are typical suggestions intended to ensure that the urea system is appropriately isolated before attempting to service the dosing cabinet.

Dosing Cabinets

Follow the steps in the System Operation Test and Adjust Service Manual to ensure that SCR system is purged of all Diesel Exhaust Fluid (DEF). DEF will crystallize and potentially damage the components in the SCR system, if the DEF is left in the system for an extended period of time.

If the catalyst or DEF nozzle remains in the exhaust flow, the dosing cabinet must remain operational and compressed air must continue to be supplied. The Dosing cabinet ECM is monitoring catalyst health even when the system is deactivated.

Transition In and Out of Regulated IMO Zones

There are three activity level configurations the aftertreatment can be placed in. Which activity level configuration is appropriate depends on the required emissions reduction for that locality and the duration of time that the engine system will be outside regulated area requiring SCR technology.

1. System Enabled - This action means that the system is either actively dosing DEF or is ready to dose DEF when engine operation and exhaust conditions mandate to meet system emissions out NOx targets.

2. System Disabled - The system has manually been put into a disabled state in which no DEF dosing will occur. The system should only be in this state when emissions regulations allow that only the engines emission control features are sufficient. In this state the SCR system remains fully installed and continues to monitor sensors and catalyst health. Both AC and DC power to the dosing cabinet should remain powered in this system configuration.

   Air supply must remain active while the engine is operational. Air supply is used to cool the dosing lance, even if the system is not actively dosing.

3. System Disabled, Components Removed - For long duration periods where only IMO II emissions levels are required, the system should be disabled and NOx sensors, Urea injection nozzle, and catalyst may be removed to prevent component aging. AC power to the dosing cabinet may be shut off.

MARPOL ANNEX VI Regulation 13.5.1

"5.3" The tier and on/off status of marine diesel engines installed on board a ship to which paragraph 5.1 of this regulation applies which are certified to both Tier II and Tier III [Tier III "Enabled"] or which are certified to Tier II only [Tier III "Disabled"] shall be recorded in such logbook as prescribed by the Administration at entry into and exit from an emission control area designated under paragraph 6 of this regulation, or when the on/off status changes within such an area, together with the date, time and position of the ship.

The enable/disable command on the Caterpillar Dosing system control can be found on the Dosing information screen. The system can be toggled on/off using the display when the vessel is enters an area where IMO II emissions levels are appropriate.

Removal from Extended Storage (DEF Remaining in Tank)

If the DEF tank was stored for a duration equal to or exceeding that listed in table at the corresponding temperature, replace the DEF.

If the DEF quality is in doubt, test with a refractometer. DEF must be within the required range defined in "ISO 22241-1". For more detailed information about testing DEF quality, contact the local Caterpillar dealer.

1. Drain DEF from the tank, and refill with DEF.

2. Replace the DEF filter. (if equipped)

3. Start the engine. If a fault code becomes active, turn off the engine, allow 2 minutes to purge, then restart the engine.

4. If a fault code continues to stay active, Refer to Troubleshooting.