Mitsui Engineering and Shipbuilding Company Limited

Kazuhiko Ohi

Yasuaki Harada

Yusai Yamahata

A fluidized bed combustion method for burning wastes using a fluidized bed furnace is not affected by a fluctuation in the quantity and quality of wastes fed into the furnace, if any, thereby preventing CO gas, etc. from discharging out of the furnace. The furnace has a number of air-diffusing tubes for feeding primary air to the fluidized bed in parallel with each other at the bottom of the fluidized bed, and a free space part formed above the fluidized bed for burning unburnt matter with a secondary air. Each air-diffusing tube has a number of nozzles provided along the axis of the tube and a primary air control device including an open-close damper for controlling the quantity of air to be fed through the tube. The primary air is fed into the fluidized bed through the air-diffusing tubes one after another according to a predetermined open-close pattern by the primary air control device so that the ratio of the air quantity Uo to the minimum fluidizing air quantity Umf (Uo/Umf) is in the range of 1.4 to 4 when the damper is opened and in the range of 0.5 to 2 when the damper is closed. The dampers are opened and closed at intervals of 1 to 10 seconds, preferably 2 to 10 seconds, and 10 to 100 seconds, respectively.

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Urayasu, Japan

Kazuhiko Ohi