EGCS Requirements. Action in case limit exceeds? (Exhaust gas cleaning System)

Answer

For EGCS (Exhaust Gas Cleaning System / scrubber), the main requirement is that the ship must demonstrate equivalent SOx emission compliance with MARPOL Annex VI Regulation 14, normally in accordance with the 2021 EGCS Guidelines, Resolution MEPC.340(77).

The system should have approved documentation and monitoring arrangements, including:

• SO₂/CO₂ ratio monitoring in exhaust gas to demonstrate equivalent sulphur compliance.

            Emissions Ratio=SO2​ (ppm) / CO2​ (% v/v)​

            Global Waters (0.50% S Equivalent): SO2​/CO2​ ratio must not exceed 21.7.

            ECAs (0.10% S Equivalent):SO2​/CO2​ ratio must not exceed 4.3

• Monitoring of relevant operating parameters such as wash-water flow/pressure, exhaust gas temperature and scrubber operating status.
• For open-loop/hybrid systems, wash-water discharge monitoring typically includes pH, PAH and turbidity as applicable.

            1) pH Limit: Minimum pH of 6.5 at 4 meters from the discharge point while stationary.                                      (Alternatively, a minimum pH of 3.0 measured directly at the overboard                                           discharge pipe prior to dilution).

              2) PAHs (Polycyclic Aromatic Hydrocarbons): Continuous monitoring to ensure                                             maximum concentration does not exceed 50 µg/L PAH_{phe}                                                          (phenanthrene equivalent) above inlet water concentration (normalized at a                                    flow rate of 45 t/MWh).

              3) Turbidity / Suspended Solids: Maximum 25 FNU (Formazin Nephelometric Units) or                                     25 NTU above inlet water turbidity.

              4) Nitrates: Maximum 60 mg/L NO3−​ (normalized for washwater flow rate), preventing                                     eutrophication

• Approved SECP / ETM / OMM, depending on the approval scheme.
• Proper calibration, maintenance and recording of monitoring equipment.
• Records of EGCS operation, alarms, malfunctions and corrective actions.

If I observe an exceedance:

1. Acknowledge alarm and verify the reading

   • Check analyzer health, calibration, sample line and sensors.
   • Confirm that it is a real exceedance and not an instrument fault.

2. Check EGCS operating parameters

   • Scrubber pumps and wash-water flow.
   • Water pressure/nozzle condition.
   • pH/alkalinity where relevant.
   • Exhaust gas flow and bypass/damper position.
   • Circulation pumps and treatment plant in closed-loop operation.

3. Reduce engine load if necessary

   • This reduces exhaust-gas mass flow and may allow the scrubber to regain compliance.

4. Restore the EGCS to compliance immediately

   • Start standby pump.
   • Clean/change strainers.
   • Rectify blocked nozzles.
   • Correct dosing/alkalinity.
   • Rectify analyzer or control-system fault.

5. If compliance cannot be restored within 1 hr, change over to compliant fuel

   • Normally fuel meeting the applicable sulphur limit:
     • 0.50% m/m globally, or
     • 0.10% m/m in a SOx ECA.

6. Record the event

   • Time and position.
   • Nature of failure/exceedance.
   • Alarm values.
   • Corrective action.
   • Fuel changeover details, if carried out.

7. Inform Master/company

   • If it is a significant malfunction or compliance cannot be restored promptly, inform Master, superintendent/DPA and follow flag/port-state reporting procedures as applicable.