Biomass small boiler

The invention discloses a biomass small boiler which is simple in structure, low-carbon and economical. The biomass small boiler comprises a boiler body and a boiler furnace arranged in the boiler body, a sealing water tank for accommodating boiler water is formed between the inner wall of the boiler body and the outer wall of the boiler furnace, an upper smoke flue is arranged on the upper portion of the boiler body, a lower smoke flue is arranged on the lower portion of the boiler body, the upper smoke flue is provided with a smoke flue port which is communicated with outside of the boiler body, a plurality of heat exchange water pipes which penetrate through the boiler furnace are arranged in the boiler furnace, a plurality of heat exchange fire pipes which are led out along the upper portion of the boiler furnace and communicated to the lower smoke flue are arranged in the sealing water tank, and a plurality of heat exchange smoke pipes which are connected to the upper smoke flue are led out of the lower smoke flue. The biomass small boiler has the advantages that on the original basis, three loops of the heat exchange water pipes, the heat exchange fire pipes and the heat exchange smoke pipes are added, the upper and lower smoke flues are combined to perform heat exchange for water in the boiler body, the heat exchange area of the boiler is increased by multiple times, the energy efficiency utilization ratio can reach to above 85%, biomass wastes such as corncobs and straws are utilized as combustion raw materials, and if the biomass small boiler is implemented for a whole year, 40% of energy expenditure can be saved each year.