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 efficiency why is it so fare in marine applications? (10)
Class 4 (4th Engineer)
SSEP
📅 Aug 2024
Reference Answer
### (a) Working Principle of Selective Catalytic Reduction (SCR) System
The Selective Catalytic Reduction (SCR) system is an after-treatment technology designed to reduce Nitrogen Oxide (NOx) emissions from marine diesel engine exhaust gas to comply with IMO Tier III regulations. Its operation is based on a chemical process that converts harmful NOx into inert atmospheric gases.
#### 1. Principle of Operation
The core principle involves injecting a reducing agent, typically a 40% aqueous urea solution (AUS 40, also known as Marine Urea), into the hot exhaust gas stream upstream of a catalytic converter or reactor. The system selectively targets NOx without affecting other exhaust gas components.
The Selective Catalytic Reduction (SCR) system is an after-treatment technology designed to reduce Nitrogen Oxide (NOx) emissions from marine diesel engine exhaust gas to comply with IMO Tier III regulations. Its operation is based on a chemical process that converts harmful NOx into inert atmospheric gases.
#### 1. Principle of Operation
The core principle involves injecting a reducing agent, typically a 40% aqueous urea solution (AUS 40, also known as Marine Urea), into the hot exhaust gas stream upstream of a catalytic converter or reactor. The system selectively targets NOx without affecting other exhaust gas components.
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