Exhaust Gas Cleaning System (EGCS) failure

What happened:

While in port, the 3/E on our ship noticed the EGCS giving some alarms during the UMS rounds. Since the EGCS was not in use, he put the alarms in the off-scan (disable) mode.

On departure, while starting the EGCS, he noticed that the AE 3 damper and uptake valves were not operating in the auto mode. Hence, he operated these valves manually. He also forgot to put the disabled alarms back in the normal mode.

During the EGCS operation, the cooling sea water pump no. 1 tripped. The standby cooling SW pumps no. 2 and no. 3 did not start on auto. The EGCS temperature started rising but did not activate any alarm as it was disabled. The high temperature shut down system tripped the EGCS. However, since the AE3 uptake / bypass valves was on manual mode, it continued to allow the exhaust gas to flow through the EGCS.

The C/E sensed burning smell in his cabin and on investigating found the cooling SW pump had tripped. He manually started the pump immediately and operated the AE3 uptake / bypass valves manually to stop the flow of exhaust through the EGCS. The engineers then tried to put the EGCS back in operation, but the high differential back pressure alarm kept tripping the system.

On internal inspection, the scrubber packing bed (demister) elements were found melted thus blocking the flow of exhaust gas through it.

EGCS Make: FMS Inc, Type: Multi Stream U-Type Open Loop, Model: FMSI 145, Design Max Exhaust Gas Flow: 122,400 Kg/h, Combustion Unit Connected: 1X ME and 3 X Aux Engine.

Lessons learnt:

• If any alarm is put on repose (disabled), ensure that:

- It is done only with permission from the Chief engineer.

- A risk assessment is carried out.

- Details are recorded in the UMS checklist.

• Check the EGCS system configuration on your ship for safe operations. Ships fitted with FMSI manufactured scrubber must specifically verify for below:

- The SW pump motor VFD is provided with additional cooling to prevent overheating.

- To standardize the maximum frequency and the limiting current on the VFD.

- All maintenance and modification of the damper valves as per makers / service engineers’ guidelines are complied with.

• Protect Alarm monitoring systems (AMS) with passwords. The CE must change the password periodically and not share it with others to prevent unauthorized access.
• Ensure that all alarms and trips as per makers manuals are included in the ships PMS and tested at the schedule intervals.