Schwalbach, Lohmar, Regensburg, November 7, 2017. At Agritechnica in Hanover, the world's leading trade fair for agricultural machinery and equipment, technology company Continental will be presenting exhaust aftertreatment solutions for agricultural and construction machinery. Continental's solutions are designed to conform to the upcoming EU Stage V emissions standards, which from 2019 will set stricter emissions limits for non-road mobile machinery. Continental's exhaust system sensors, selective catalytic reduction (SCR) dosing modules and metallic catalyst substrates provide the basic components for a highly efficient overall system.
Metallic catalyst substrates with customizable, easily integratable oval or even asymmetrical geometries allow the catalyst system to be mounted directly on the engine. Continental will also be displaying the ring catalyst, which makes it possible to achieve a highly integrated design in which the entire aftertreatment system, including the SCR injection system, is housed in a single box. These two strategies – direct mounting on the engine and use of a standardized box – not only ensure efficient emissions reduction but at the same time make it possible to cater to as many different vehicle applications as possible. In the agricultural and construction sectors, engines are fitted in a wide variety of vehicle types, and production volumes are usually small. For each of these applications, the aftertreatment system requires individual validation and certification. Cost savings are just one of many advantages if an aftertreatment system can be used across a wide range of applications.
“The more compact the aftertreatment system is, the more easily it can be integrated in multiple applications,” says Rolf Brück, head of the Catalytic Converters product line in Continental's Fuel & Exhaust Management business unit. “Continental can offer all the necessary exhaust aftertreatment components for such solutions. And this means we are able to implement highly efficient Stage V systems for a wide range of applications.”
Customized geometry and intelligent nested design
EU Stage V will set stricter limits on emissions of nitrogen oxides (NOx) and particulates from non-road machinery compared with the current US Tier 4 final/CARB and EU Stage IV standards. At the same time, new trends like the use of tractors in urban or construction applications mean that the aftertreatment system must function over a wider range of operating conditions. When a tractor is used for ploughing, its engine operates close to its design point, i.e. in the most efficient operating range. In an application such as urban snow removal on the other hand, the engine will not be running at much more than idling speed. Exhaust gas aftertreatment systems must therefore be designed to function reliably under a wide spectrum of operating conditions.
As a result, exhaust aftertreatment systems for this sector are becoming ever more extensive in scope. As well as an oxidation catalyst and particulate filter, they also feature selective catalytic reduction (SCR) of nitrogen oxides (NOx), and in some cases also an ammonia slip catalyst. The SCR system in turn comprises the SCR catalyst itself and also a system for dosing and injecting the reducing agent (ideally without using a mixer), along with sensors and actuators. If these components are all to be located in close proximity to the engine, compact design is essential. “With a metallic catalyst substrate and customized geometries, Continental provides the basis for an easily integratable solution with good backpressure characteristics,” says Brück. “Our ring catalyst solution allows the catalyst to be positioned around a particulate filter. At the present time there can be few, if any, more efficient solutions to the space issue. This configuration even creates room in the box for a second SCR system. A second SCR injection helps to ensure near-complete conversion of nitrogen oxides even in full-load operation.”
In urban applications with low engine loads, a heated catalyst can ensure that NOx conversion is maintained at all times. “Since this technology too was developed by Continental, it can be seamlessly incorporated in a compact and highly integrated solution,” says Brück.
