TIER 4 INTERIM / STAGE IIIB EMISSION STANDARDS FOR NON-ROAD MOBILE MACHINERY

Transcription

1 TIER 4 INTERIM / STAGE IIIB EMISSION STANDARDS FOR NON-ROAD MOBILE MACHINERY

2 TIER 4 INTERIM / STAGE IIIB EMISSION STANDARDS FOR NON-ROAD MOBILE MACHINERY On January 1, 2011, the Tier 4i / Stage IIIB emission standard came into effect for industrial engines used in non-road mobile machinery with a power rating of kw ( bhp). More specifically, the American Standard EPA Tier and the European standard Stage both specify requirements for reduced emissions of Oxides of Nitrogen (NOx) and Particulate Matter (PM, or soot). Oxides of Nitrogen and soot are a threat to public health and the environment, especially when present in the atmosphere in high concentrations. EMISSION STANDARDS Stage I, the first emission standard for industrial engines in Europe, dates from Over time, the standard has evolved to today s more stringent Stage IIIB, with Stage IV taking effect from The figure below (Figure 1) shows the evolution of the European standards, with permitted NOx and PM emissions at each stage. Figure 1 - EU Emission Standards, Stage 1 - Stage IV

3 The highest standards worldwide apply in North America (EPA Tier), Europe (Stage) and Japan (MLIT). Figure 2 shows geographically where each emission standard is applicable in Figure 2 Emission standards Tier 4 Final /Stage IV not yet applicable. Figure 3 shows the situation in effect from The highest standards apply in North America, Europe and Japan. Countries with emerging economies (large parts of Asia, South America and Australia) are catching up. Figure 3 Emission standards Tier 4 Final /Stage IV in effect.

4 CATERPILLAR TIER 4I / STAGE IIIB SINGLE FLUID SOLUTION To reduce NOx emissions from a diesel engine to within the Tier 4i standards, there are two technically very distinct technologies. One method, used especially in the road transport sector, is known as SCR (Selective Catalytic Reduction). This uses a catalytic converter in which a water-urea solution (AdBlue in Europe, DEF or BlueTec in the US) is injected into the exhaust gases to reduce NOx emissions. However, some disadvantages remain. In places where industrial engines are used (construction, agriculture, irrigation, remote sites, etc.), local availability of the additive cannot always be guaranteed, and its consumption is an additional cost. The second method of NOx reduction, which Caterpillar has chosen for its Tier 4i / Stage IIIB engines, is exhaust gas recirculation, or EGR. In this process, a portion of the exhaust gases is cooled and dosed back into the cylinders of the engine (Figure 4). Before they reach the atmosphere, the engine exhaust gases are cleansed of harmful partially or wholly unburned substances such as fuel or oil in the Diesel Oxidation Catalyst (DOC, see figure 5, without the addition of a urea solution. A Diesel Particulate Filter (DPF, see Figure 6) intercepts the particulate matter (PM, soot). The Caterpillar Regeneration System (CRS) prevents the Clean Emissions Module from clogging. Using heat from the exhaust gases, or from a diesel-powered afterburner (Figure 8), the CRS burns off the soot trapped in the DPF, reducing it to a tiny amount of ash, enabling the Clean Emissions Module to run for thousands of hours without the need for major servicing. The electronic motor management coordinates the automatic operation of the entire system. Aside from diesel fuel, no other fluid is required for Tier 4i / Stage IIIB-compliant operation of a modern Cat industrial engine with an NOx reduction system that uses exhaust gas recirculation (EGR), a Clean Emissions Module (CEM) comprising a Diesel Oxidation Catalyst (DOC), and a particulate filter (DPF) with a regeneration system (CRS): CAT Single Fluid Solution. Figure 4 Exhaust gas recirculation (EGR) A portion of the exhaust gases is passed through the exhaust gas cooler back to the engine air intake.

5 Figure 5 - Diesel Oxidation Catalyst (DOC) The DOC is a catalytic converter comprising a ceramic element coated with precious metals such as palladium and platinum. Thanks to the Flow Through design, the DOC is maintenance-free, it has no moving parts, and it works without chemical additives. In the DOC, environmentally-hazardous substances are rendered harmless. Poisonous carbon monoxide is converted into harmless carbon dioxide. Hydrocarbons (fuel, oil particles) are transformed into carbon dioxide and water vapor. Figure 6 Diesel Particulate Filter (DPF) This soot filter reduces particulate emissions by 90%. The filter element is made from a material with a fine cellular structure. In the Wall-Flow design of the DPF, the exhaust gas enters the filter via open channels with a sealed end, forcing the gas to exit through the walls. The fine, porous structure of the filter element traps the solid particles on the inflow side of the channel walls in the DPF.

6 Figure 7 Cat Clean Emissions Module (CEM) Electronically controlled automatic exhaust aftertreatment system (CEM), assembled from the Diesel Oxidation Catalyst (DOC), particulate filter (DPF) and active regeneration system (CRS). The particulate filter (DPF) is a replaceable cartridge. Figure 8 Caterpillar Regeneration System (CRS) Active regeneration system. Afterburner in foreground.

7 FLEXIBILITY PROVISION Tier 4interim / Stage IIIB is the emission standard applicable to engines brought to market between January 1, 2011 and December 31, 2013 ( kw, bhp)<. From the above it can be concluded that making the engine cleaner has major implications for manufacturing. The exhaust aftertreatment system requires considerable space and a significantly higher financial investment, compared to engines built before Subject to certain conditions, the governments of the US, Canada and the EU are offering machine producers the option of building-in a limited number of engines from the previous emission generation (Tier 3 / Stage IIIA, kw, valid until end of 2013). Any machine producer wishing to make use of this flexibility provision can request permission from their government. 2014: TIER 4 INTERIM / STAGE IIIB BECOMES TIER4 FINAL / STAGE IV Even with Tier 4i / Stage IIIB, the journey towards cleaner engines is not yet over. In 2014, the step will be made towards Tier 4 / Stage IV ( kw). Once again, a new range of technical features will be needed to make the engines compliant with the more stringent NOx standard applying at that time. Given the current stage of development of the required technology, it can already be concluded that Caterpillar s next step towards the cleanest possible diesel engines will again be on time and successful. More information: For more information on non-road emission standards, applied emission reduction technology and the flexibility provision: Pon Power BV Reinier Platschorre Project Manager Industrial OEM E: reinier.platschorre@pon-cat.com T: Jan Nederlof Account Manager Industrial OEM E: jan.nederlof@pon-cat.com T: Adriaan Mijnster Account Manager Industrial OEM E: adriaan.mijnster@pon-cat.com T: