Catalytica's Xonon Low-NOx Technology is a Winner with Pratt & Whitney Canada

Catalytica Combustion Systems, Inc., a subsidiary of Catalytica, Inc. (Mountain View, Calif.), and Pratt & Whitney Canada, Inc. (P&WC), a subsidiary of United Technologies Corp., announced the first industrial gas turbine engines to use Catalytica's Xonon combustion system. Xonon has been selected for the ST18, as well as for the ST30, a new gas turbine announced separately today. While previous commercialization agreements have focused on retrofit applications, the P&WC/Catalytica accord represents the first in which a gas turbine manufacturer is applying Xonon to a new OEM gas turbine.

The Xonon system is a breakthrough technology that essentially eliminates the formation of nitrogen oxides (NOx) and certain other harmful air emissions in gas turbines. Pratt & Whitney Canada, Inc. (P&WC) and Catalytica Combustion Systems, Inc. have signed an agreement for the first step in commercialization of a family of engines to use the Xonon system. The first phase is a demonstration program to design, develop and install Xonon on the ST18 gas turbine. The ST18 turbine produces up to 2.3 MW of power; the ST30 will produce up to 4 MW. Deliveries of these engines, with Xonon, are expected to begin in the year 2001. Before selecting Xonon for the ST18 and ST30 turbines, P&WC evaluated a number of low-NOx technologies for these high-efficiency turbines.

Temperature control
Catalytica, which was founded in the mid-1980s to pursue novel types of catalysis technology, offers the Xonon unit as part of the combustor of a gas turbine; a turbine maker like P&WC provides the rest (Figure 1). The combustor features a catalyst module that accepts a fuel/air mixture and burns it flamelessly at a controlled temperature below where NOx would be formed. (The company has tested its technology at temperatures as high as 1500°C [2730°F]). Catalytica says that a "chemical thermostat" is part of the catalyst module that keeps a close control on combustion temperature, and also that the lower temperature allows a lower-cost, metal matrix to be used as a catalyst support (rather than a ceramic one). A burnout zone follows, in which CO and unburned hydrocarbons are oxidized. The resulting gas passes into the turbine inlet.

Figure 1

The system also depends on controls provided by Woodward Governor Co. (Rockford, Ill.) to provide a smooth startup, optimized performance, and problem-free turndown. A year ago, Catalytica and Woodward formed a joint venture, Genxon Power Systems, and announced an agreement with General Electric to provide Xonon systems as retrofits to GE turbines worldwide.

The performance characteristics of the system, which Catalytica has previously tested on a 1.5-MW, Kawasaki M1A-13A unit, are NOx emissions below 3 ppm, and CO/hydrocarbon emissions below 10 ppm. Standard turbines with no NOx controls can produce NOx at levels as high as 150 ppm. The alternative techniques-running at fuel-rich conditions or injecting water to lower combustion temperature-can reduce emissions by 10 percent or more, but raise CO/hydrocarbon emissions. The third major alternative, use of a selective catalytic reduction unit after the turbine-has a substantial capital cost and operating penalty (Figure 2).

Figure 2

"By incorporating Xonon, our turbines will offer a compelling combination of exceptionally high thermal efficiency and proven reliability, with an ultra-low emissions profile, ideal features for the rapidly expanding distributed power generation market," said Gilles Ouimet, president of P&WC.

"Pratt & Whitney Canada's decision to become the first turbine manufacturer to offer a family of commercial engines which emit less than 3 ppm NOx is setting a new standard for gas turbines," said Dennis Orwig, president of Catalytica Combustion Systems. "We look forward to working with Pratt & Whitney to reduce the time required to bring the ST18 and ST30 to the world-wide power generation market. We believe the environmental, operational, and economic benefits of Xonon will give P&WC's engines a first-to-market competitive edge."

By Nick Basta

Contact: Catalytica, Inc., 430 Ferguson Drive, Mountain View, CA 94043-5272, Tel: (650)960-3000; Fax: (650)960-0127.