Optimization Of Desuperheating Water And Energy Saving Reconstruction Of Heating Surface Of A 600MW Sub-critical Boiler

A 2x600 MW boiler designed by East Boiler company was investigated. The boiler was DG2030/17.45-Ⅱ8 subcritical, hedge wall before and after combustion, double tail flue structure, natural circulation drum boiler.Since the unitswere put into operation, there had been phenomeons of desuperheated, reheated tube wall temperature, desuperheating water flow more than design value. Under the condition of the coal in the power plant had large deviation comparing to the design value of the coal, the problemwas more outstandingand may directly affect the safety of the unit operation economy and regulation. To reduce the boiler desuperheating water flow and improve the operation efficiency, the company had taken many measures. Such as enhancing the soot blowing of the boiler furnace and economizer blowing, reducing the soot blowing of heating surface on desuperheater and reheater, lower the burner flame center height as far as possible, keeping low excess air coefficient, avoiding the combustion wind and so on, but the effects were not ideal.This paper aimed at the 2 boilers desuperheating water flow on the high side at present was about the problem of the comprehensive research and analysis. Based on the work of peer and data collection, Scheme of remoulding the boiler heating surface for energy saving was presentedto solve the problem of large boiler desuperheating water flow. We calculated the thermal state of the boiler, tested the thermal efficiency of the boiler under the working condition of 600 MW, 450 MW and 300 MW. The smoke temperature and oxygen percentage composition at the air preheater were measured; the proximate analysis and calorific value of the row coal were measured; the ash was collected and the proximate analysis was taken. The results showed that the thermal efficiency had improved 0.377% after renovation and the desuperheating water flow decreased 187.2t/h at the desuperheater and 108.5t/h at the reheater.The safety and economical efficiency of the boilers were improved after the energy saving renovation. Comparing the effects of energy saving before and after the remoulding, technical reference could be provided to the same type of units in the same industry.