Question 93Steam Plants - Assistant Engineer

The correct answer is B) control steam admission and maintain the proper steam spray pattern in the DC heater. The steam control valves installed in the auxiliary exhaust line are used to regulate the flow of steam into the DC (deaerating) heater. This is necessary to maintain the proper steam spray pattern and ensure efficient deaeration of the condensate before it enters the main condenser. The steam control valves allow the operator to adjust the steam flow to match the system's demands and maintain the proper operating conditions in the DC heater. The other answer choices are incorrect because they do not accurately describe the purpose of the steam control valves in the auxiliary exhaust line. Option A is incorrect as the valves do not preheat the condensate. Option C is incorrect as the valves do not regulate back pressure in the desuperheater line. Option D is incorrect as the valves do not seal the vent condenser.