Sacramento Power Plant Showcases New, Advanced Ultra-Low NOx Burner

Coen Company, Inc.98, California faced a thorny problem with its General Services Heating and Cooling Plant in Sacramento. The plant, which heats and cools 23 government buildings, had difficulty achieving full capacity using a set of new, low-emission burners installed to meet 30 parts per million (ppm) of nitrogen oxide (NOx) emissions, a major contributor to ozone pollution and photochemical smog.

Ironically, the plant's customers include the state capitol building, where senators and assemblymen have enacted some of the nation's strictest air-quality legislation.

However, despite earlier difficulties, the Sacramento plant today serves as a showcase for the first installation of one of the most advanced emissions-performance technologies on the market, the QLA Ultra-Low NOx Watertube Boiler Burner. With the installation, the plant has achieved full compliance and is no longer challenged to meet its operating permit. NOx emissions from one of the facility's two natural gas-fired boilers dropped more than 70%—from more than 30 ppm to less than 9 ppm.

Besides achieving extremely low NOx emissions, the plant operates the boiler at maximum efficiency, saving more than $75,000 annually in fuel costs. These savings don't include the avoided costs of other, more costly NOx reduction options. For example, use of standard low-NOx burners and selective catalytic reduction (SCR) to achieve ultra-low NOx emissions requires about $6,000 of capital costs and $1,300 for operating costs per ton of NOx removed. Corresponding costs for the QLA burner are $2,800 and $0, respectively.

"We can comfortably guarantee emissions below 9 parts per million with 400° Fahrenheit pre-heated air, which ensures maximum boiler efficiency. That's a major accomplishment",said Steve Londerville, vice president of R&D and chief engineer at Coen Company, which manufactures the burner."

Coen worked with the Chicago-based Gas Research Institute (GRI) to develop the burner. Robert Gemmer, GRI project manager, said the ability to achieve ultra-low NOx emissions using pre-heated air remains the most significant aspect of the technology. "This is extremely difficult to do. Previously, you had to sacrifice emissions if you wanted to achieve high efficiency. Conversely, complying with emissions regulations meant relinquishing efficiency," he said. With the QLA burner, you can-in effect-have your cake and eat it, too."

The QLA burner uses a proprietary process in which the staged mixing of air, fuel and flue gas recirculation minimizes formation of NOx in the flame. Development of the burner started in October 1994, when Coen was selected to develop a boiler burner capable of emitting single-digit NOx. GRI, the natural gas industry's research, development and commercialization organization, led the $3.3 million program, which included funding from the Southern California Gas Company, Los Angeles, and the California Air Resources Board (CARB). Also participating were the University of California at Irvine, and Arcadis Geraghty & Miller.

While current emissions regulations do not require ultra-low NOx emissions, the GRI partnership foresees an emerging market for such burner applications. "We anticipate that several market drivers will begin motivating end users to adopt advanced technologies that allow them to exceed emissions limits," Gemmer said. "These drivers include the merits of over-controlling one major source to avoid installation of new equipment throughout a facility, trading emissions credits in areas with cap-and-trade procedures in place, and as a hedging strategy against future, more stringent regulations."

Gemmer said GRI also believes that ultra-low NOx technologies will begin to capture the attention of plant operators, especially those operating in regions with marginal air quality. The QLA burner, he said, can be installed at a fraction of the cost of the lowest priced post-treatment systems. In addition, plant operators are finding they can significantly reduce capital investments and still achieve full compliance by converting a few burners with the ultra-low NOx option instead of converting multiple burners to conventional low-NOx burners. "The strategy is simple. If you over-comply on one unit, you can avoid the high costs of making capital investments on another."

In the meantime, the GRI partnership is working on the next generation of ultra-low NOx burners. An Optical Flame Management Scanner is being developed that will allow the QLA burner to achieve its ultimate NOx emissions-reduction capability. Coen expects the scanner will be market ready in about 18 months.

Coen specializes in the design, manufacture, servicing, and maintenance of burner equipment and combustion systems. With more than 10,000 installations worldwide, Coen burner equipment and combustion systems provide optimum performance, meeting the needs of the industrial boiler, utility boiler, cogeneration, wood products, pyro-processing, solid fuel, refinery, oil recovery/steam flood and petrochemical industries.

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Edited by April C. Murelio
editor@poweronline.com