Limitations of mass transfer cause combustion processes to be imperfect and to produce such polluting byproducts as oxides of nitrogen (NOx), soot, and incompletely-oxidized hydrocarbons. NOx has been identified as a significant contributor to the formation of ozone in the lower atmosphere. Stationary sources of NOx are regulated under provisions of the Clean Air Act Amendments of 1990. Methods of control are available for stationary sources operating at or near steady state, but none have been demonstrated for jet engine test cells (JETC), which operate at transient conditions that vary drastically during operation.
The objective of this project was to develop a NOx emission control technology that can be used on JETCs.
This project (1) built and installed an engineering test facility on an operating JETC at McClellan Air Force Base (AFB), CA, to evaluate the practicability of controlling JETC emissions directly, (2) assembled a prototype control device and applied it to three stationary, near-steady-state sources to measure efficiency and cost of control, and (3) assembled a prototype control device and performed in-lab and on-the-road testing on exhausts from a gasoline- powered automobile and a diesel truck.
The jet engine test cell control system was operated for two multiple-day shake-down tests. Vibrational loads on the system were sustained successfully, and NOx removals of more than 99 percent were attained. The full-scale system operated better than predicted from bench and slip-stream analyses. Preliminary economic analyses predicted control costs of $10,000/ton of NOx. Demonstration of the NOx filter cart was extended to a slipstream from the 500 hp diesel generator at McClellan AFB. Results proved the versatility of the filter cart concept, as removal of NOx was over 95 percent. Scaling of the filter has been proven at several levels. A lab-scale system was constructed to investigate and design in-place regeneration for the NOx filter cart. All preliminary results indicate the concept will work and will be incorporated in future designs of the NOx filter cart.
For the stationary and mobile near-steady-state sources, the payoffs are a quantitative improvement in pollutant removal; a decrease in the cost and effort to maintain the control devices; wider operating windows for temperature and throughput; and avoidance of the liability of storing, handling, and possibly leaking hazardous materials used in selective reduction methods. For all applications, the treatment residue is nonhazardous and beneficial to plants, allowing horticultural disposition, which avoids the cost of disposal of process-derived hazardous wastes.