Experimental investigation on the feasibility of a movable heat-insulation device

Currently, many boilers in China can not burn low rank coals and low-calorific-value gases (blast-furnace gas, converter gas, etc.) stably and/or efficiently and have a poor adaptability to frequent variation of load and fuel rank. Moreover, the temperature and pressure of the generated steam deviate a lot from the nominal value and can not meet the users’ demand. In order to resolve these problems, a microporous ceramic-board-based movable heat-insulation device is devised. The board is installed on a furnace waterwall tube and can be moved up or down during operation so as to maintain a properly high and quasi-constant temperature in the near burner zone in the case of low load or low rank fuel. The structure, working principle and feasibility of the device are introduced and analyzed. Finally, encouraging calculation and experiment results are demonstrated. The results show that the device can work safely and reliably in low-calorific-value gas fired furnaces and all kinds of stoker-based furnaces and has very good potential for improving the overall performance of a boiler in terms of the combustion stability and efficiency, the adaptability to load and fuel.