Split-Range control in boiler feed water applications

摘要

In power plants as well as chemical or petrochemical plants, processes frequently involve water being fed into a boiler where it is heated to a certain temperature. When starting up the boiler, the amount of water is still small and the boiler pressure is still low. The feed pressure exceeds the boiler pressure later prevailing during continuous operation. The required amount of feed water is controlled over one or more control valves. This control task can be rather demanding as the sample application from a refinery dealt with in this article illustrates. We will point out opportunities of optimizing boiler feed water applications both during start-up and continuous operation by using appropriate control valves and valve sizing as well as well-adjusted split-range control.