Class 2 (2nd Engineer) MEKG 📅 Jan 2025

Exam Question

(a) Describe, with the aid of a sketch, an open loop system for reducing SOx emissions from engine exhaust gas, explaining how the system operates whilst the vessel is in open waters. (8)

(b) Describe, with the aid of a sketch, a closed loop scrubber system for removing SOx from engine exhaust gas, explaining the operation of this unit and stating when it would be used. (8)

Reference Answer

### (a) Open Loop Exhaust Gas Cleaning System (EGCS)
An open loop scrubber system is an Exhaust Gas Cleaning System (EGCS) that utilizes the natural alkalinity of seawater to neutralize Sulphur Oxides (SOx) present in the engine's exhaust gas. This system is predominantly used when the vessel is operating in open waters, where the discharge of treated wash water is permitted under MARPOL Annex VI regulations.
**Principle of Operation**
The fundamental principle relies on the chemical reaction between the acidic SOx in the exhaust and the alkaline bicarbonate ions (HCO₃⁻) naturally present in seawater. The SOx is absorbed into the seawater, forming sulfurous and sulfuric acids, which are then neutralized.

Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.

View plans Browse library

← Browse more questions

Prepare on Android — MeoMock on Google Play