Improvement of cyclic operation on pulverized coal fired boilers by applying wide range burners

There are recently urgent requirements to operate pulverized coal fired power plants as well as oil fired units cyclically or at low loads. In order to cope with this, wide range burners (WRB) were jointly developed to obtain a high turndown operation by the Central Research Institute of Electric Power Industry (CRIEPI) and Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI). In accordance with the results of various fundamental researches, including combustion tests with a tunnel furnace of 12 MW[thermal], it was confirmed the stability of the flame and the combustion characteristics at low loads as well as that of ordinary burners. The WRB have been applied to the new actual boilers that are Saijo Power Station NO. 2 unit of Sikoku Electric Power Co., Inc., Nanao-Ota Power Station NO. 2 unit of Hokuriku Electric Power Co., Inc. and Miike Power Station NO. 1 unit of Miike Thermal Power Co., Ltd.. The results of the trial operation have shown that the minimum burner load was below half of that of conventional burners, and accordingly the pulverized coal firing minimum load could be reduced. This paper explains about the cyclic operation of their boilers and the improvement effect by applying WRBs.