Question 52 QMED01 - Junior Engineer

The Correct Answer is A. ### Why Option A ("contaminated drain system") is correct: Condensate return lines from tank heating coils (e.g., fuel oil storage tanks, cargo tanks in maritime applications) heat the contents of the tank using steam. Since these coils are immersed directly in the product (such as fuel oil, cargo, etc.), there is a constant risk of the coil developing a leak. If a leak occurs, the product being heated (the contaminant) will mix with the steam and thus contaminate the resulting condensate. This contaminated condensate must **not** be returned to the clean feedwater cycle (like the main condenser or deaerator) because it would foul the boilers, turbines, and heat exchangers. Therefore, condensate from tank heating coils must be strictly segregated and routed to the **contaminated drain system** for proper handling and disposal, usually after being monitored or stripped of oil/impurities. ### Why the other options are incorrect: * **B) DC heater (Direct Contact Heater / Deaerating Condenser or Deaerator):** The DC heater is a critical component for heating and deaerating clean feedwater before it is sent to the boiler. Introducing potentially contaminated condensate from tank coils here would immediately foul the boiler feedwater system and potentially damage the boiler. * **C) atmospheric drain tank:** While contaminated drains often pass through an atmospheric drain tank, the atmospheric drain tank itself (in the context of steam plant terminology) typically collects uncontaminated drains (like gland sealing steam drains or low-pressure clean drains) that might be flashed to the atmosphere and later returned to the clean system. The specific designation "contaminated drain system" (or contaminated drain collecting tank) is necessary to ensure the separation and specialized treatment of the effluent from tank coils. * **D) main condenser:** The main condenser is where the clean, spent steam from the main turbine is condensed back into water to be returned to the feedwater system. Introducing contaminated condensate to the main condenser would pollute the entire primary condensate cycle, leading to severe operational issues and equipment damage in the boilers and heat exchangers.