Gordon J. Bartley

Stoichiometric Operation of a Gas Engine Utilizing Synthesis Gas and EGR for NOx Control

This paper presents the results from an internal research study conducted at the Southwest Research Institute (SwRI) on the effects of stoichiometric mixtures of natural gas and synthesis gas with exhaust gas recirculation (EGR) on engine performance and exhaust emissions. Constant load performance and emissions tests were conducted on a modified, single-cylinder, Caterpillar 1Y540 research engine at 11.0 bar (160 psi) bmep. Engine performance and emissions comparisons between natural gas with EGR, and natural gas with syngas and EGR are presented. In addition, the performance characteristics of the fuel reforming catalyst are presented. Results show that thermal efficiency increases with increasing EGR for both natural gas operation and natural gas with syngas operation at constant load. The use of syngas with natural gas extended the EGR tolerance by 44.4 percent on a mass basis compared to natural gas only, leading to a 77 percent reduction in raw NOx emissions over the lowest natural gas with EGR NOx emissions.

Alternative catalytic approach for reduction of cold-start hydrocarbon emissions

This paper describes an alternative approach to reduction of cold-start hydrocarbon emissions that allows the engine to operate under rich conditions for stable operation, and makes use of that rich condition to reduce overall hydrocarbon emissions. The approach requires only the addition of a small catalyst with particular catalytic properties. No additional hardware is required, and secondary air pumps, hydrocarbon adsorbers, electrically heated catalysts, heat storage devices, etc. can be removed from the vehicle. Reductions of 30–40% in hydrocarbon emissions were realized over the US FTP-75 test, without changes in calibration, when compared to the base catalyst systems.

Protection of Aftertreatment Systems from Sulfur, PASS-2™ - Advanced System Design Evaluation

This study was performed by the Department of Engine and Emissions Research under an SwRI® Internal Research and Development Program. The objective of the study was to evaluate the effectiveness of a system design that was an advancement over SwRIs patented Protection of Aftertreatment Systems from Sulfur (PASS) technology.[1,2] A Lean NO x Trap (LNT) was employed as the sulfur-sensitive emissions reduction device. Lean Sulfur Traps (LST) and Rich Sulfur Traps (RST) were formulated to provide the sulfur protection. Testing was performed to evaluate the efficiency of the LNT, the sulfur poisoning of the LNT, the efficiency of the LST, and the regeneration and protection characteristics of the PASS-2 system. The program successfully demonstrated that an LST upstream of an LNT does provide protection for the LNT from the adverse effects of fuel-borne sulfur. The work also demonstrated that the LST could be desulfurized, with all of the product sulfur species passing through the LNT, without adversely affecting its performance. These two results validated the PASS-2 advanced system design. The data also suggested that an LST could be effective at storing sulfur from 8 ppm sulfur diesel exhaust at very high efficiency for a minimum of 50,000 miles. A single desulfurization of the LST could release most of the stored sulfur in less than five minutes, with only a minor impact on fuel economy. A temporary deactivation of the LNT was reversed within five minutes, so the NO x emission impact would also be very minor. The lack of high temperature required to regenerate the LNT would result in significantly increased durability of the LNT. In essence, the PASS-2 system could be used to maintain emissions efficiency over 435,000 miles for heavy-duty applications, with an estimated nine desulfurizations of the LST during that period, when the system is fully developed.