Question 33 QMED01 - Junior Engineer

The Correct Answer is B **Why Option B ("turbine-driven feed pump") is correct:** An excess pressure governor (also known as a constant differential pressure governor or excess pressure regulator) is specifically designed to maintain a constant pressure differential between the steam supply pressure (to the pump turbine) and the discharge pressure of the pump (the feedwater header pressure). This differential pressure ensures that the pump is always generating enough pressure to overcome the boiler drum pressure and push the feedwater into the boiler, regardless of variations in boiler steam pressure or pump speed. Turbine-driven feed pumps are critical components in boiler systems, and maintaining this precise pressure relationship is essential for proper boiler operation and water level control. **Why the other options are incorrect:** * **A) low-pressure propulsion turbine:** Propulsion turbines are controlled by speed/load governors (to regulate RPM and output horsepower) and overspeed trip mechanisms, not typically by an excess pressure governor that manages a differential between steam and water discharge pressure. * **C) forced draft fan:** Forced draft fans are typically controlled by speed or damper position regulators based on boiler furnace pressure (draft) requirements or combustion air flow, not by a differential pressure relationship tied to a water discharge system. * **D) main circulator pump:** Main circulator pumps (or main circulating water pumps, usually found in power generation or HVAC/cooling systems) manage the flow of cooling water. Their control systems focus on flow rates, discharge pressure (absolute pressure), or temperature control, not the specific function of maintaining a constant pressure differential between the steam driving the pump and the water the pump is discharging into a high-pressure system like a boiler.