 0. Online consultation SZS Series of Industrial Natural Gas Fired Water Tube May 00, 0000 · Introduction of SZS Gas Fired Double Drum Steam Boiler. SZS gas fired double drum steam boiler is designed with longitudinal double drums and " D " type chamber structure. Furnace is placed on the right and convection tube bank is on the left, super heater is ... Online consultation SZS Double Drums Packaged Steam Boiler - Gas Fired Boilers SZS series boiler is designed with longitudinal double drums and " D " type chamber structure. Furnace is placed on the right and convection tube bank is on the left, super heater is arranged at convection tube bank. The body is fixed on the basement by middle and both end flexible supports and make the boiler expand horizontally sideways.