Superheated steam temperature control with radiant energy as calorific value signal

Traditional control system for boiler superheated steam temperature regulates desuperheating water flow through testing the superheated steam temperature and its variation trend,thus keeping the temperature of superheated steam within a permissible range.The considerable delay in change of superheated steam temperature with respect to disturbance of desuperheating water flow,however,leads to the lagging in superheated steam temperature control and as a result the control effect is not satisfying.On account of the fact that the signal of total boiler radiant energy fully embodies the changes of combustion conditions in a boiler and can foreshow the variation trend of inlet flue gas temperature,the signal of total boiler radiant energy is introduced in the control system for superheated steam temperature.Desuperheating water flow is regulated in advance through testing the flue gas temperature and its variation trend,so as to improve the control on main steam temperature.With this method,regulation tests were made on Unit 5(300 MW) in Shajiao A Power Station at constant and varying loads and the results were satisfactory.