Several obvious problems occurred in a subcritical 300 MW circulating fluidized bed(CFB) boiler

such as over high bed temperature

non-uniformity bed temperature distribution

and severe coking near part of the back wall.To solve these problems

the air distribution uniformity on air distributor of the boiler before and after the transformation of air volume adjustment/air distributor for the primary air branch were experimentally investigated.The results show that

for the rectangular air box with dual air inlets

there was obvious non-uniformity along the width direction of the air distributor.By adjusting the airflow volume on the left and right sides of the air box

the average air speed deviation of the left and right wall sections could be reduced

but the average air speed deviation between the central region and the two side regions couldn't be obviously reduced.After the air distributor throttling optimization

the overall uniformity was significantly improved.The low air speed area in the middle was improved

and the uniformity of the bed temperature was also significantly improved after optimization.