Cummins Inc. (Cummins) has provided air-fuel ratio control system to meet 2007/2008 Environmental Protection Agency (EPA) Spark-Ignition New Source Performance Standard (SI NSPS) emissions standards and is focused on lowering natural gas emissions for EPA 2010/2011 with in-house technology. The company has developed a new air-fuel ratio control system that employs a dithering control algorithm with dual-loop feedback for rich-burn engines.
Cummins utilizes the advantage of both lean-burn and rich-burn combustion technology depending on the emissions levels to be attained.
Building on current engine control capability, Cummins has developed a proprietary air-fuel ratio control system that employs a dithering control algorithm with dual-loop feedback for rich-burn engines. With 200 tests and over 4,000 test hours on the engine and emissions control system, Cummins engineers have developed a new reliable and durable air-fuel ratio controller and catalyst combination that is integrated with today’s new engine. Cummins tests validate the air-fuel ratio control system’s capability to compensate for environmental variations such as humidity, catalyst inlet temperature, fuel quality and air intrusion into the exhaust stream.
“The new air-fuel ratio control system compensates for degradation of the O2 switching sensor, improves catalyst oxygen storage, prolongs the life of the catalyst and improves its efficiency. All of these enablers help keep your engine in compliance between maintenance checks,” says Al Weber, Cummins Natural Gas Engine chief engineer.
Cummins rich-burn natural gas engines are supplied with three-way catalysts from Cummins Emission Solutions and employ Cummins Electronic Control Modules (ECM). Having complete ownership of these in-house technologies and subsystems allows Cummins engineers to integrate these systems more effectively through the development of new natural gas products.
Cummins new 2010 NSPS technology allows a customer to buy a complete engineered package from one supplier. This also allows for emissions solutions and points of contact from sales, support and application engineering to come from the same company. Cummins is able to offer complete emissions solutions from 84 to 760 hp (63-567 kW) with emissions down to 0.5-gr/hp-hr Oxides of Nitrogen (NOx) to meet current and future emissions requirements. Lean-burn engines are available from 175 to 850 hp (130-634 kW) with 2-gr/hp-hr NOx emissions to meet the current EPA requirements. In addition to the industrial natural gas engines, Cummins also offers natural gas gensets powered by lean-burn natural gas engines from 334 kWe to 2 MW with NOx emissions from 0.7 to 1.0 gr/hp hr.
“Looking to the future, Cummins understands that emissions standards will continue to become more stringent. With 2010/2011 EPA SI NSPS on tomorrow’s doorstep and oil and gas fields developing in non-attainment areas, meeting future emissions requirements will continue to be at the forefront of all new Cummins engine development programs,” states Rusty Downey, Cummins Gas Compression Segment leader.
Cummins is a US-based manufacturer and distributor of engines and related technologies.