WOODY PELLET BURNING STEAM BOILER

PROBLEM TO BE SOLVED: To provide a woody pellet burning steam boiler allowing reduction in size, stable and efficient combustion of woody pellets, improvement in the efficiency due to good load followability, and prevention of reduction in the efficiency. SOLUTION: The woody pellet burning steam boiler is constructed of an inner water cooling wall 2 forming a combustion chamber S2 inside, an outer water cooling wall 3, arranged on the outside of the inner water cooling wall 2, a combustion gas passage 4 formed between the both water cooling walls 2 and 3 and connected to the combustion chamber S2 and a flue 9, respectively; an upper header 5 and a lower header 6, respectively connected to the upper and lower end parts of the both water cooling walls 2 and 3 in a communicating manner; a combustion device 7 arranged below the combustion room S2 and using the woody pellets F as fuel; and a purge air supply mechanism 8 feeding purge air P to the bottom part of the combustion gas passage 4. From a woody pellet supply port 30a in the upper part of the combustion chamber S2, the woody pellets F are thrown into the combustion chamber S2, to be burnt by the combustion device 7, and generated combustion gas G and burnt ash are discharged from the combustion chamber S2 to the flue 9 via the combustion gas passage 4. COPYRIGHT: (C)2008,JPO&INPIT