The natural gas industry has long depended on large bore, two-stroke cycle, spark-ignited, gas-powered, reciprocating engines to move gas from the well to the pipeline and downstream. As regulations governing the pollutant emissions from these engines are tightened the industry is turning to the engine OEMs for a solution. The challenge of further reducing engine emissions is not a new task to the industry. However, as the requirements placed on the engines are further restricted, the technology required to achieve these goals becomes more advanced, along with the required tools and technology to create it. New predictive tools have been created and have become more powerful and capable as computer software and hardware becomes more advanced, enabling engineers to create more complex designs and to do so quickly and at lower cost, all of which may not have been possible previously. This paper investigates methods used in designing the Ajax 2800 series, which is a large bore, two-stroke cycle, gas-powered, reciprocating engine and the improvements in emissions that resulted from the application of these methods.. Solutions to overcoming the challenges encountered during the process will also be presented.

Large bore, spark ignited, reciprocating, gas engines have been the workhorse of the pipeline industry for many years when it comes to transmission of gas. Recently, the US government has released an update to the NSPS and RICE NESHAP regulating emissions from many of these engines to [1]: • 1gbhp·hgbhp-hrNOX • 2gbhp·hCO • 0.7gbhp·hVOCs (Non-methane, non-ethane hydrocarbons) This new rule leaves many of these legacy engines out of compliance with the standard. Because of this, engine operators are left with the choice of decommissioning these engines as they come due for compliance based retrofit or working with engine OEMs to implement an emissions reduction strategy. For many years, the traditional methods and tools used for engine design were more than enough to create a successful engine. But with tightening restrictions and higher expectations for customers and the amount of improvement that can be extracted from design changes shrinking with every redesign, these methods by themselves are no longer sufficient. This paper will examine modern design methods and tools available to an engine designer as well as their integration with more traditional testing methods. A comparison of results for the redesigned COOPER BESSEMER® GMVH-6C3 will also be presented for analysis.

This paper presents results from Phase 2 of the development of an Active Air Control (AAC) system to balance air flow into each cylinder of a turbocharged engine system, a PRCI-funded emissions reduction project. Imbalance in air flow creates a discontinuity in trapped equivalence ratio from cylinder to cylinder. Trapped equivalence ratio is directly proportional to NOX production and a function of the fuel flow rate, air flow rate, and, in a two-stroke cycle engine, the scavenging efficiency. Only when these three characteristics are balanced cylinder to cylinder will the combustion and the NOX production in each cylinder be equal. The engine NOX production will be disproportionately high if even one cylinder operates less lean relative to the other cylinders. This paper reports on the testing of an AAC system on a two-cylinder air flow bench at the National Gas Machinery Laboratory at Kansas State University. The results from these tests were then used to further validate the comprehensive, variable geometry, multi-cylinder flow model referred to as the Charge Air Integrated Manifold Engine Numerical Simulation (CAIMENS). CAIMENS is a manifold flow model coupled with the T-RECS engine processor that uses an integrated set of fundamental principles to determine the crank angle-resolved pressure, temperature, burned and unburned mass fractions, and gas exchange rates for the cylinder. CAIMENS has been validated with data from the NGML multi-cylinder flow bench. This information has allowed the research team to (1) quantify the impact of air flow imbalance and (2) provide detailed information leading to the specification of the active air flow control system. The end point of this project is an AAC system that can, with some engineering effort, be applied to field engines.

A problem-based learning activity has been developed using automotive engineering and requirements of the Clean Air Act to examine complex environmental issues involving automobiles. After an introductory study, students sample the O 2 , CO, NO, and NO 2 levels of automobile exhaust and analyze the results. The activity employs a constructivist approach and is appropriate for entry-level engineering classes. It can be modified for use in upper level engineering classes as well. To prepare for the emissions analysis lab, students study the composition of atmospheric gases, products of combustion, and the measurement of automotive emissions. The laboratory component is the actual sampling of engine exhaust from student selected automobiles using an exhaust emissions analyzer. Students use sample values of emission concentrations for O 2 , CO, NO, and NO 2, combustion kinetics, and fluid dynamics to calculate the engine fuel flow rate, exhaust flow rate, and mass emission rates for CO and NO X . This paper presents an overview of the introductory studies followed by a description of the automobile exhaust sampling activity. Representative sample data of automobile emissions are presented along with a discussion of the sampling results, a method for approximating pollutant mass emission rate levels, and comparison to EPA standards.

This paper presents an investigation into CO formation in large-bore two-stroke cycle (2SC) lean-burn engines. On March 5, 2009, the Environmental Protection Agency (EPA) proposed a new rule to addressing National Emission Standards for Hazardous Air Pollutants (HAP) for existing stationary reciprocating internal combustion engines. Specifically, the 2009 Proposed Rule identifies carbon monoxide (CO) as a surrogate for HAP and requires reductions in CO for 2SC lean-burn engines. This future promulgation has created the need for a comprehensive kinetic CO formation model. The CO model itself integrates equilibrium concentration values of CO with the CO concentration created later in the cycle from the dissociation of equilibrium CO2. The previously developed variable-geometry multi-cylinder Turbocharged-Reciprocating Engine Compressor Simulation (T-RECS) has been modified with a mechanism to model cycle-resolved CO formation using a calibrated kinetic reaction scheme. The simplified chemical kinetic CO reaction scheme has been tuned and validated with exhaust concentration data collected on a Cooper GMVC large-bore two-stroke cycle engine, and directly relates the impact of engine operating conditions and in-cylinder geometry.