Exam Question
(a) How does the Selective Catalytic Reduction (SCR) system work? (10)
(b) If Selective Catalytic Reduction (SCR) has such an extremely high NOx reduction efficieney why is it so rare in marine applications? (10)
Class 4 (4th Engineer)
SSEP
📅 Jun 2024
Reference Answer
### (a) Working Principle of Selective Catalytic Reduction (SCR) System
#### 1. Fundamental Principle
The Selective Catalytic Reduction (SCR) system is an after-treatment technology designed to reduce Nitrogen Oxide (NOx) emissions from diesel engine exhaust gas. Its primary purpose is to enable vessels to comply with the stringent IMO Tier III NOx emission limits. The system selectively converts harmful NOx into harmless diatomic nitrogen (N₂) and water (H₂O) using a reducing agent (ammonia) and a catalyst.
#### 2. Key Components
#### 1. Fundamental Principle
The Selective Catalytic Reduction (SCR) system is an after-treatment technology designed to reduce Nitrogen Oxide (NOx) emissions from diesel engine exhaust gas. Its primary purpose is to enable vessels to comply with the stringent IMO Tier III NOx emission limits. The system selectively converts harmful NOx into harmless diatomic nitrogen (N₂) and water (H₂O) using a reducing agent (ammonia) and a catalyst.
#### 2. Key Components
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