Study on thermal characteristics of a high temperature air combustion boiler (1st report, experimental demonstration)

A new concept compact boiler using high temperature air is proposed and experimental demonstration is done. In the boiler, high temperature air combustion is realized. Fuel can be efficiently burned by high temperature preheated air of about 800°C∼1 000°C under low oxygen content (∼5%). The temperature distribution in the furnace is very uniform and there is no hot spot, so that low NO.v emission (∼40 ppm) and relatively high .average temperature in the furnace can be achieved. Thermal efficiency of more than 90% is accomplished including waste heat recovery of exhaust gas. This boiler is useful to partial load operation, because the response of thermal output is linear. This boiler is also suitable for low calorific value gas derived from gasification process of coal and wastes with no dioxin emission. Simulated low calorific value gas made from natural gas diluted with argon can be burned with low NO_x emission.