Closed-Loop Scrubber (EGCS)

Exhaust gas cleaning system that uses caustic soda (NaOH) in a closed water loop to remove SOx; sludge stored aboard for shore disposal.

In practice

Used in waters that prohibit open-loop discharge. Caustic dosing rate set by exhaust SOx; the engineer monitors fresh-water makeup and effluent settling tank level. Sludge handled as MARPOL Annex I oily residue.

Regulatory detail & full definition

More expensive to operate (NaOH consumption + sludge offload) but allowed in port-discharge restricted waters. Wash water passes through hydrocyclones and a sludge tank. Some ports require closed-loop operation only.

Authoritative source: IMO Resolutions Index ↗

Open-Loop Scrubber (EGCS)

Source: MEPC.259(68); MEPC.184(59)

High confidence

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Closed-Loop Scrubber (EGCS)

In practice

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Closed-Loop Scrubber (EGCS)

In practice

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