How to operate Exhaust gas cleaning systems (EGCS)?

28 Sep '21, 18:41

Sept. 28, 2021, 6:41 p.m.
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Do not operate EGCS in open loop in ports / waters which prohibit the discharge of washwater effluent.

Operate the EGC system as instructed in the makers instruction manual. Operation will depend on the type of EGC and operation mode (open/close loop). Following are some generic operating guidelines.

Start-up sequence

  • Set valves in correct position (open/close) for the operational mode (open or close loop)
  • Ensure monitoring systems display normal status
  • Ensure all liquid in the system is prepared for start-up
  • Start main pumps at low RPM
  • Start fans at low RPM and gradually increase RPM to design point
  • Start pre-injection pump (where fitted)
  • Increase main pump RPM to design point
  • Start waste treatment unit (WTU)
  • Close permanent bypass hatch
  • Start NaOH dosage pump (close loop)

Normal operation check-list

  • Signs of any leaks
  • Signs of vibrations
  • Signs of excessive heat
  • NaOH storage levels

Maintain the operating parameters of the EGC system within the limits or range of operating values given in the technical file (ETM – A/B):

Exhaust gas

  • Mass flow rates - maximum and if applicable minimum
  • Inlet temperature ranges
  • Outlet temperature – max. and min.
  • Differential pressure range and max. gas inlet pressure

Wash water

  • Flow rate - max. and min.
  • Inlet pressures
  • Inlet water alkalinity
  • Salinity levels or freshwater elements necessary to provide adequate neutralizing agents
  • Discharge criteria for PH, PAH, turbidity and temperature, as per ETM A/B
  • Other factors / restrictions concerning the operation of the EGC unit.

Alarm functions:

Monitor alarms and ensure its proper functioning by regular testing as per PMS. The alarms fitted would depend on the EGC make and type but following is a general list:

  • Excessive gas pressure at exhaust gas meeting point
  • High SO2 [ppm]/CO2 [%]
  • Low liquid flow
  • High/low liquid pressure
  • Low level NaOH storage tank
  • High temp exhaust outlet

Record keeping


  • Data Recording and Processing device automatically records several parameters
  • EGC record book approved by the administration used for recording maintenance, servicing, adjustments, consumption of spares, chemicals etc.
  • Maintenance records may be in the Ships PMS as approved by the administration
  • Engine log book and PMS records also verified during surveys
  • Retain records for a period of not less than 18 months from the date of recording
  • Provide Administration or PSC with downloaded copy of the recorded data and reports as requested

Data recording and processing device:

The data recording and processing device monitors and records automatically the following EGCS parameters:

  • When the system is in use, time against Universal Coordinated Time (UTC) and vessel position by Global Navigational Satellite System (GNSS) position
  • Washwater pressure and flow rate at the inlet connection
  • Exhaust gas pressure before and pressure drop across the scrubber
  • Engine and/or boiler load(s)
  • Exhaust temperature before and after the scrubber
  • Exhaust gas SO2 and CO2 content
  • Washwater - PH, PAH, turbidity and temperature

EGC record book:

Record in the EGC record book the following:

  • Daily spot checks of the SO2(ppm)/ CO2 (%) if not fitted with a continuous exhaust gas monitoring system (Scheme A)
  • Daily spot checks of the EGCS parameters if fitted with a continuous exhaust gas monitoring system (Scheme A where fitted and Scheme B)
  • Chemical consumption for units consuming chemical at a known rate
  • Maintenance, Servicing and Spares consumption (if not covered in the PMS approved by administration)
  • Storage and disposal of washwater residues (sludge) including the date, time and location of delivery to shore reception
  • EGCS mal-function including date and time the mal-function began, how resolved / actions taken to resolve and any follow-up actions


Do not incinerate or discharge overboard wash water residues. Retain on board for disposal ashore. EGCS inspection and maintenance Maintain sufficient stock of neutralizing agent (caustic soda) for EGCS operating in close loop.

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28 Sep '21, 19:04

Sept. 28, 2021, 7:04 p.m.
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