Keep temperature control out of hot water

摘要

Think of a heat exchanger as a controller for which the gain varies inversely with flow.At minimum water flows,a small increase in steam flow will produce a certain steady-state rise in water temperature.When the water flow is doubled,the same size increase in steam rate results in only half the water temperature rise.This varying gain can be compensated for by using an equal-percentage steam valve for which the gain varies directly with its delivered flow.