After reviewing the current combustion technologies for burning pulverized coal with frequent and large fluctuations in coal quality and load demand, a new concept of quasi-constant temperature combustion for pulverized coal is proposed. In this method, combustion temperatures near the burners are maintained almost constant using a moveable multilayer heat-insulation device, which is installed on the fire-side of the furnace water-wall and can be moved up and down during operation. The results obtained from numerical modeling and experimental investigation show that such an insulation device can greatly improve the distribution of the flue gas temperature and can maintain the temperature effectively constant near the burner for a wider range of boiler load if the heat-insulation area of the MHID is sufficiently large. In addition, such quasi-constant temperature combustion can remarkably decrease losses of unburned materials at low loads. It can be inferred from the experiments that MHID has a good chance of being applied in practice. (C) 2003 The Combustion Institute. All rights reserved.