Low-pressure feedwater heaters are exposed to the discharge pressure of which type of pump?

Low-pressure feedwater heaters are designed to utilize the thermal energy from the steam or hot water passing through them to preheat the feedwater before it enters the boiler. The pressure at which low-pressure feedwater heaters operate is significantly influenced by the type of pump connected to them.

In this context, extraction pumps are specifically designed to draw steam from a turbine or another high-pressure system. The steam pressure from which it is extracted is usually at a lower pressure than the full boiler steam pressure, making it suitable for heating feedwater but not directly appropriate for boiler feedwater application. This allows low-pressure feedwater heaters to efficiently increase the temperature of the incoming feedwater, improving thermodynamic efficiency in the steam cycle.

Low-pressure feedwater heaters differ from other types of pumps such as circulating pumps, which mainly move water in a closed loop for cooling or heating; cooling water pumps, which deal with water used for cooling and condensation; and boiler feedwater pumps, which typically operate under high pressure to deliver water directly to the boiler. Therefore, the extraction pump's discharge pressure critically governs the operational characteristics of low-pressure feedwater heaters.