Question 54

The Correct Answer is C **Explanation for Option C (main condenser):** The main purpose of the low-pressure (LP) turbine is to extract the last useful energy from the steam before it is exhausted. To maximize efficiency and allow the steam cycle to restart, the spent steam leaving the LP turbine must be rapidly converted back into water (condensate). This process occurs in the **main condenser**, which maintains a high vacuum (very low pressure) to draw the steam out of the turbine and facilitate heat transfer, typically by using cooling water (e.g., from a river, lake, or cooling tower). **Explanation of Incorrect Options:** * **A) feed and filter tank:** This is a component in the boiler feedwater system, typically located much further along the cycle *after* the condensate has been processed and deaerated, and is not the immediate destination for spent turbine steam. * **B) first-stage feedwater heater:** Feedwater heaters are used to preheat the water (feedwater) *after* it has left the condenser and condensate pump. They warm the water before it enters the boiler or steam generator, thus increasing thermal efficiency; they do not handle exhaust steam directly from the turbine. * **D) turbine extraction valve manifold:** Extraction valves manage steam that is *removed* from intermediate stages of the turbine (before the LP exhaust) to supply steam to components like feedwater heaters. They do not handle the final exhaust steam leaving the LP turbine.