Method and apparatus for supplying feedwater to a forced flow boiler

摘要

An apparatus and method of supplying feedwater to a forced flow boiler or the like as described. A positive displacement pump having a plurality of discrete pumping elements is arranged to pump feedwater from an inlet to the boiler. The pump includes bypass valves which, when open, disable the pumping action of an associated pumping element. Control means responsive to the demand for water in the boiler are arranged to disable a selected number of the pumping elements so that the rate of water supplied by the remaining elements, if operated continuously, would just exceed that required. The control means is further arranged to disable at least one of the remaining pumping elements on a periodic basis so that the ratio of time that the element is enabled to the time for one period multiplied by the water flow rate supplied by said element, if operated continuously, equals the difference between the total demand for water and the rate supplied by the pumping elements enabled on a full-time basis.