The Clayton Feedwater Pump is a pack-less and seal-less positive displacement type oil reservoir and diaphragm pump. It utilizes the diaphragm to isolate the feedwater in the pump column from the hydraulic oil in the crankcase. Water is drawn through the inlet check valves and discharged through the outlet check valves as the column of water is moved by the diaphragm.
In modulating units, feedwater flow is controlled by varying the speed of the feedwater pump using a variable speed drive. Flow varies directly with speed because Clayton Industries uses a positive displacement pump. For example, at 40% of boiler output, the pump runs at 40% of full/maximum speed. In step-fired units, flow varies within the pump itself or by operating in speed steps.
Clayton Industries’ positive displacement feedwater pump continuously delivers feedwater through the heating coils. This efficiently maintains a wet tube condition under all operating loads. The pump can handle water up to 464° F (240° C) and the output flow is not affected by back pressure.
The pump’s diaphragms are operated hydraulically by oil displaced within the pump crankcase. The pistons are in contact with the hydraulic oil and not with the feedwater. Tubular cooling columns separate the check valve housings from the pump heads which reduces diaphragm temperature. The low-speed design ensures reliable long-term continuous-duty operation.
Long-life corrosion resistant springs, disks and seats are used in the check valve housings. Snubbers are added to absorb pressure pulsations and ensure a stabilized water flow. A relief valve protects the pumps against excessive overpressure.
An optional float-operated pump level switch is available and provides additional protection from an oil level that is too low or too high inside the pump. Optional pump head cooling is also available for high-temperature feed systems, such as deaerator, semi-closed and high pressure (over 500 psig) applications.
See Boiler and Steam Deinitions for terms.