To address the complex effect of inlet parameters on combustor performance, a statistically based technique is applied to a model, premixed natural gas fired combustor. In this way, multiple parameters are simultaneously investigated for their contribution to combustion performance. Atmospheric tests are performed at conditions otherwise representative of industrial combustors: 670 K. inlet preheat and an equivalence ratio of 0.47. Experimental results, in combination with CFD modeling, reveal that (1) the statistical approach is an effective tool by which parameters that dominate performance can be identified, (2) the principal statistically significant parameter linked to NOx production is the inlet fuel distribution, (3) the principal statistically significant parameter linked to CO production is swirl solidity, and (4) an inlet fuel distribution that features a concentration peak in line with the shear layer of the recirculation zone yields NOx levels comparable to a well premixed case.

A Kawasaki Heavy Industries M1A-13X gas turbine engine equipped with a Xonon Cool Combustion® System was used to validate performance of a next generation catalyst module design incorporating advanced catalyst materials over 8000 hours of continuous operation. The unit ran unattended, 24 hours a day, 7 days a week connected to the electrical grid. NOx emissions were measured to be less than 2.5 ppm throughout the guaranteed operating load range (70–100%). CO emissions were measured to be less than 10 ppm; typically less than 1ppm across the same load range. The new catalyst module design incorporates features and technology developed during the past several years where durability was a primary focus. Performance test results from previous durability tests were used to develop theoretical predictive models. These models proved invaluable in determining the optimal catalyst formulation as well as the required operating conditions throughout the life of the combustion system. Successful validation of the new catalyst module design has led to incorporation of these advanced materials and design techniques in commercial products and prototype units. It is believed that continued technology development, as well as performance data gathered from field units, will support extending product life beyond the current guarantee of 8000 hours.

A new bypass system using an improved design has been fabricated and tested on a Kawasaki M1A-13X gas turbine engine. The engine and catalytic combustor are currently installed at the City of Santa Clara’s Silicon Valley Power municipal electrical generating stations and connected to the utility grid. The use of a bypass system with a catalytic combustor, incorporating the Xonon Cool Combustion™ technology, on an M1A-13X system increases the low emissions load turndown and ambient operating range without impacting engine efficiency. The increased operating range is achieved because the bypass system provides the required adiabatic combustion temperature (Tad) in the combustor’s post-catalyst burn out zone without changing the turbine inlet temperature. A detailed measurement of the pressure drops, in the old bypass system, revealed that there were large flow losses present, particularly in the re-injection spool piece and the extraction plenum. Since it was determined that the spool had the highest pressure loss, this was the component targeted for improvement. The analysis coupled with detailed measurements on the reinjection piece revealed that the effective area actually varied with flow As the flow changed, so did the flow mechanics inside and exiting the spool piece. Therefore, in order to achieve the design target, the flow area of the spool piece had to be optimized at the predicted capacity flow rate. CFD analysis of the spool piece revealed the regions of losses in the re-injection piece. This analysis along with a one-dimensional flow analysis of the entire system enabled the design of new spool re-injection piece. Once the design was completed, the new bypass system was fabricated and tested. Bypass flow capacity was increased by about 22%. This was achieved by alleviating regions of flow losses and also by using a new “scoop” design for the bypass reinjection tubes. As expected, engine turndown capacity and ambient operating range were improved with the new design.

A Kawasaki Heavy Industries M1A-13X engine equipped with a Xonon® Cool Combustion System was used to assess the “effectiveness” of a post-catalyst burnout zone liner. The engine is currently installed at the City of Santa Clara’s Silicon Valley Power municipal electrical generating stations and connected to the grid. Post-catalyst burnout zone liner aero-thermal design and inlet boundary conditions play an important role in achieving low CO emissions. In this particular study, these parameters have been evaluated to minimize CO emissions (by maximizing CO burnout). An aero thermal analysis was conducted using Computational Fluid Dynamics (CFD) simulations of the liner for two distinct engine configurations. The analysis includes characterization of the inlet boundary conditions, heat transfer analysis, ignition delay time, liner residence time and the aerodynamic flow field. In addition, engine tests were used to measure and evaluate the impact of design features on CO emissions. Tests were conducted using new seal design and catalyst liner interface configurations. Results from both of these investigations were then used to determine the “effectiveness” of the liner. The CFD analysis and engine test data identified potential regions of improvement to maximize CO burnout in the Burn out Zone (BOZ) liner. These improvements included changing the inlet boundary conditions as well as modifying the BOZ geometry. Ultimately, a solution scheme was selected and changes were made to the catalyst seal design as well as the catalyst to container interface. Upon implementation, these changes yielded an improved effectiveness and extended the operating range of the engine by minimizing CO emissions.