A dryback boiler has a rear wall that is lined with refractory, a wetback boiler has a rear wall that is jacketed by water. Because of this fact, wetback boilers typically boast higher efficiency than dryback boilers as the heat from combustion goes directly into heating water instead of refractory. Wetback boilers are also more forgiving with load changes as the reversal chamber of the boiler is totally submerged in water creating an even heat transfer on the intermediate tube sheet to furnace joint.
Any boiler where the products of combustion flow on the inside of a tube with the heat transfer media (ex. water, steam, or hot oil) on the outside. The tubes can be orientated vertically, horizontally or at an angle.
1. In terms of boiler body structure, WNS series gas-fired (oil-fired) boilers are fire tube boilers; SZS series gas-fired (oil-fired) boilers are water tube boilers;
2. In terms of boiler working pressure, if the boiler pressure is below 1.6Mpa, the choice is usually the WNS series gas-fired (oil-fired) boiler, if the boiler pressure is above 1.6Mpa, the SZS series gas-fired (oil-fired) boiler may be a better solution. Some high-pressure boilers also adopted SZS series gas-fired (oil-fir...
