ZOZEN WNS series gas-fired steam boiler adopts the large-diameter corrugated furnace and threaded smoke tube to increase the heating surface, reduce the thermal stress and improve the boiler's safety performance; meanwhile, in order to reduce the heat loss caused by gas exhaust and operating costs, ZOZEN also adds energy-saving devices at the end of the flue gas duct to improve the thermal efficiency to over 98%. In addition, the two sets of boilers also meet the ASME standards, which proves that ZOZEN product quality is up to international standards.