We use water to generate steam in the thermal power plant. We supply water to the boiler and the boiler converts this water into hot water then to steam. This input water to the boiler is known as feed water. When feed water gets supplied to the steam drum of the boiler, feed water pump is used to increase the pressure of the water. The feed water pump feeds water to the boiler and this feed water may be a fresh supply of water or reuse of water after the process of conduction. We measure the capacity of feed water pump in horsepower and we use an electric motor to drive this pump. The capacity of an electric motor (kW rating) is higher than the capacity of a pump (HP rating).
According to construction, two types of feed water pump are available, simplex feed water pump and duplex feed water pump. A simplex feed water pump has one set of steam and water cylinders and duplex feed water pump has two sets of steam and water cylinders. Both sets are not physically connected but the working of both pumps is dependent on each other. Both pumps have separate rod (shaft) and steam valves. Operation of first pump’s steam valve depends on the movement of the second pump’s piston rod and the operation of second pump’s steam valve depends on the movement of the first pump’s piston. This pump can start from any position of the rod and steam valve and this type of construction make pump self-starting and there are no dead-spot in operation, this is the main advantage of duplex feed water pump.