A set of industrial boiler with sufficient output and stable heating supply can directly affect the daily production of a food company. ZOZEN DZL series biomass-fired steam boiler adopts the single-drum longitudinal layout and chain grate stratified combustion method. ZOZEN technicians has optimized the design of the feed hopper, grate width and length, speed of grate reducer and position of secondary air outlet by analyzing the different fuel characteristics and practical use requirements of customers to ensure the sufficient combustion of biomass pellets and improve the combustion efficiency. Meanwhile, DZL series biomass fired steam boiler adopts the thread smoke tubes developed by ZOZEN to strengthen the heat transfer and improve the thermal efficiency. The heat transfer coefficient of thread smoke tube is 1.8 times higher than that of ordinary smoke tube and the thermal efficiency of boiler is over 88%, which can fully meet the daily production demands of enterprises.