The causes leading to somewhat large temperature difference of the drum-wall after shutdown of HG 220/9.8-YM10 type boiler in Yuancun Thermal Power Co Ltd in Guangzhou City have been analysed. It is considered that the main causes are as follows:(1) the pressure decreasing velocity in steam water system is too fast; (2) the water level in the drum is somewhat lower; (3) supplying makeup water is more frequently; (4) adopting boiler shutdown method under complete pressure and so on. For these reasons

some controlling measures have been put forward

namely the steam pressure decreasing velocity should be controlled as slow as possible; sliding parameter boiler shutdown mode should be adopted; the times of supplying make-up water should be decreased as less as possible under prerequisite of maintaining higher water level in the drum. After adopting said measures

temperature difference of the drum-wall after boiler shutdown has been basically controlled into a allowable range.