Class 2 (2nd Engineer) MEKG 📅 Jul 2024

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. (6)

(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. (10)

Reference Answer

### (a) Open Loop Exhaust Gas Scrubber System (6 Marks)
An open loop Exhaust Gas Cleaning System (EGCS), or scrubber, utilizes the natural chemical properties of seawater to remove Sulphur Oxides (SOx) from the engine exhaust gas. This system is predominantly used when the vessel is operating in open waters where the discharge of treated wash water is permitted.
#### Principle of Operation
The fundamental principle is the reaction between the acidic Sulphur Oxides in the exhaust and the natural alkalinity of seawater. Seawater contains bicarbonate ions (HCO₃⁻) which act as a buffering agent, neutralizing the sulfurous acid formed when SOx dissolves in water.

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