This paper compares DZL and SZL chain grate boilers for factory use. DZL is a single-drum packaged boiler with fast installation, low cost and high efficiency, suitable for 1–10 t/h small and medium-sized production. SZL is a double-drum boiler with strong load capacity, stability and long service life, ideal for 4–35 t/h large-scale continuous production. Selection should be based on capacity, space, budget and load demand.