Demonstration of a Novel Ultra-Low Oxides of Nitrogen Boiler for Commercial Buildings

The Gas Technology Institute, along with Power Flame, Inc.; Tetra Tech, Inc.; Southern California Gas Company; and Mission Linen Supply, demonstrated an emerging efficient low oxides of nitrogen burner technology, termed dynamic staged entrainment. The burner incorporates dynamic flow geometry that induces entrainment of cooled products of combustion to provide greater spatial uniformity in the distribution of the reacting species, heat release rates, and temperatures. In addition, the technology allows for staging of combustion reactants within the combustion chamber, providing further thermal distribution within the chamber. These features minimize localized high-temperature regions within the flame thereby limiting production of thermal oxides of nitrogen.

The project team installed the dynamic staged entrainment burner demonstration with a commercial fire tube boiler at Mission Linen Supply in Santa Barbara, California. The technology offers a simple design well-suited for application to commercial water heating/steam generation. The burner consistently achieved emissions below 9 volumetric parts per million oxides of nitrogen (NOx) without the need for costly and complex selective catalytic reduction applied downstream of the boiler to remove NOx from the exhaust stream. The technology also offers advantages over other alternatives for NOx reduction including external flue gas recirculation, whereby exhaust products from the boiler stack are returned to the burner inlet or burner operation at high excess air levels. Compared to flue gas recirculation systems, the dynamic staged entrainment burner achieves similar or improved efficiency, with further reductions in air blower power. In comparison to high excess air burners, the dynamic staged entrainment burner is 2 percent more efficient and requires significantly less electric power to drive the combustion air blower. The dynamic staged entrainment technology offers a cost-competitive alternative to currently available equipment for the commercial hot water/steam generation market in California in an easy-to-operate and simple design.

Extensive evaluation of the technology for more than 10,000 hours of real-world conditions have proven this burner is capable of meeting low NOx levels while operating with relatively low excess air and high efficiency levels. The demonstration documented 9 percent savings in fuel usage compared to the baseline conventional boiler. This result highlights the benefits of applying a newer reliable boiler/burner technology, which can provide significant energy and cost savings to commercial buildings.