SZL packaged water-tube hot water boiler is the double-cylinder, water-tube assembly, chain grate boiler. Two cylinders are laid at the upper and lower level of boiler longitudinally along the center. Front section of the upper cylinder and water-cooled tubes at side walls form the radiation-heating area in the hearth. While the rear section and tube bank in the lower cylinder serve as convection-heating area, the coal economizer is mounted at the rear of boiler. Some heat of hot combustion fume is absorbed by the hearth, then hot combustion heat flows to the convection heating area through cooling chamber and exhausts outside through the chimney via coal economizer, dust collector and draught fan. http://www.wuxishenneng.com