Question 51

The Correct Answer is B **Explanation for Option B (contaminated drain system) being correct:** Condensate return lines from tank heating coils (especially cargo tanks, fuel oil tanks, or lubricating oil tanks) are routed to a **contaminated drain system** (or observation tank/sump leading to this system) because there is a high risk of contamination. If a coil leaks inside the tank, the contents of the tank (e.g., fuel oil, lube oil, or cargo) will contaminate the steam/condensate. This contaminated condensate must be prevented from returning directly to the boiler feedwater system, which could severely damage the boiler due to scale formation or corrosion. The contaminated drain system ensures the fluid is collected, monitored, and then either treated or discharged appropriately (usually incinerated or sent to a slop tank). **Explanation of why other options are incorrect:** * **A) main condenser:** The main condenser is designed to handle clean exhaust steam from the main turbines, which is intended to be recycled as boiler feedwater. Introducing highly contaminated condensate from heating coils here would compromise the entire boiler feedwater system. * **C) atmospheric drain tank:** While atmospheric drain tanks (or inspection/observation tanks) collect various drains, the critical distinction is that *contaminated* drains are explicitly segregated from *clean* drains (like those from deck machinery heating or low-pressure clean services) that might be routed back to an atmospheric drain tank for eventual return to the feedwater system. Condensate from tank heating coils is considered inherently contaminated and is usually directed to a specialized contaminated drain tank or observation tank leading to the contaminated system. * **D) DC heater (Direct Contact Deaerating Feed Heater):** The DC heater functions to preheat and de-aerate the clean boiler feedwater before it enters the boiler. Like the main condenser, it is part of the clean feedwater cycle. Introducing contaminated condensate here would pollute the high-purity feedwater essential for safe boiler operation.