Confronted with the increasingly severe environmental protection policies, ZOZEN has made progress in the research and development of technologies in recent years. WNS series gas-fired boilers with features of high efficiency and low emissions are preferred by the industrial boiler market. This series of boiler adds a radiant heating surface to increase the heat transfer coefficient. Besides, the boiler adopts high-efficient threaded flue tubes to slow down the flue gas flow rate and fully absorb heat. In addition, energy-saving devices are equipped at the tail of the flue to increase the thermal efficiency to above 98%. The efficiency is superior to level 1 national energy efficiency standard. Moreover, the advanced low NOx burner greatly reduces the emission of NOx to 30 mg/m3. The ultra low emission provides guarantees for clean production and sustainable development of enterprises.