Abstract: Monitoring of evaporating tube wall temperature mainly relies on a certain number of thermocouples outside the furnace and it lacks effective methods inside the furnace. Through the modeling of wall heat transfer, furnace heat flux distribution and tube dimension as well as the simulation of forced convective boiling heat transfer in the wall tubes, online measurement of the whole-furnace evaporating wall temperatures and the firing coal calorific value is achieved with a monitoring and forecasting system successfully developed and applied for a 1 000-MW supercritical boiler. The performance tests on the system are carried out, which show that the difference between the on-line monitoring value and the value measured by the thermocouples ranges from -2.47% to +3.83% and the error of the on-line monitoring of the coal low calorific value on as-received basis ranges from -6.99% to +5.32%.

Key words: supercritical pressure once-through boiler, furnace, wall temperature monitoring and forecasting, on-line coal calorific value measurement