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Diesel emissions and exhaust after treatment
- 1. Diesel Emissions and Exhaust After-Treatment for Modern Diesel Technology National Biodiesel Board Technician Outreach Program Rachel Burton & David Stehouwer 2009
- 3. US On Highway Emissions Standards 1988 1990 1991 1994 1998 2000 2002 2010 0.80 0.33 0.134 0 2 4 6 8 10 12 NO x , g/kW-Hr Particulate, g/kW-Hr 8.05 6.7 6.7 5.4 3.3 1.5 0.013 14 16 14.4 2007 0.27
- 4. Fuel technology Combustion technology Aftertreatment technology Fuel system technology Better understanding of combustion Alternate Fuels (Biodiesel) Low sulfur De-NOx DOC PM trap Rate control High pressure Multi-injection EGR technology Others Control technology Emission Reduction in Diesel Engines
- 15. Selective-Catalysts Reduction (SCR) Aqueous Urea Solution Tank Ammonia Slip Catalyst Engine 1 2 3 4 5 6 T Air Induction Pump and Injector Atomized Urea Solution Catalyzed Particulate Filter SCR Catalyst Air to Air Cooler C Reference: DDC Turbo-Charge NO EGR
Notas del editor
- Most of you have seen this slide, which discloses the various technologies that are being applied to achieve Tier 2-4 emissions levels. I will only discuss the fuel system where the migration to common rail systems are a key leverage for achieving low emissions.
- Injection pressure requirements for large engines have evolved from the stringent emissions requirements and a desire to achieve as low an in-cylinder NOx, smoke and particulate solution as possible. This is to reduced the burden on future aftertreatment systems. For Tier 2 and 3 we were able to avoid use of aftertreatment, but for Tier 4 it seems clear some aftertreatment will be required. HPCR is a necessary building block in the total system for emissions solutions. It offers improvements in NOx, fuel economy, smoke, noise, UHC, CO and particulate control that would not be available through conventional mechanical or electronic unit injection systems. The multiple injection events, injection rate control, and precision injection timing control over the life of the engine are critical to achieving and maintaining emissions without deterioration.
- Injection pressure requirements for large engines have evolved from the stringent emissions requirements and a desire to achieve as low an in-cylinder NOx, smoke and particulate solution as possible. This is to reduced the burden on future aftertreatment systems. For Tier 2 and 3 we were able to avoid use of aftertreatment, but for Tier 4 it seems clear some aftertreatment will be required. HPCR is a necessary building block in the total system for emissions solutions. It offers improvements in NOx, fuel economy, smoke, noise, UHC, CO and particulate control that would not be available through conventional mechanical or electronic unit injection systems. The multiple injection events, injection rate control, and precision injection timing control over the life of the engine are critical to achieving and maintaining emissions without deterioration.
- This 6-sigma critical parameter flowdown is meant to illustrate how we try to tie the controlled properties of commodity diesel fuels to those properties that fuel system manufacturers required. The Red boxes are the ones most critical to us, and unfortunately are generally the least controlled by the refiners and fuel delivery infrastructure. And only through disciplined and expensive sampling can the fuel properties even be ascertained to be acceptable. These only are snapshots of the fuel quality and not representative of the total time history of fuel consumed by the engine. So for the most part, end customers get a wide range of fuel qualities, most within the broad specification of ASTMD975 or EN590 and outside North America and Europe the control of fuel quality is even less disciplined There are some notable exceptions -- certain areas like western Canada where the refiners of synthetic crude derived from tar sands seem to have excellent control over fuel quality.
- Water in fuel can also aggravate HPCR wear through corrosion products that are as hard as hard particles. And they can serve as growth mediums for microorganisms that plug filters and create acids and ions that promote corrosion and deposits. Freezing of water in fuel is problematic during cold weather operation. Reaction of water concentrates of acids and bases to form organic soaps that plug filters is less well understood. Under extreme conditions these can plug injector orifices and nozzles. And lubricity can be drastically reduced with only 1000 ppm of water in fuel.
- Highly refined S15 UltraLow Sulfur (ULSD) diesel fuel may have additive packs to improve lubricity and corrosion resistance, but these may lower interfacial surface tension on filter medias that make water removal more difficult. Fuel Water Separation is more challenging as biodiesel percentages increase, and solvency of biodiesel blends makes coated cellulose media less effective.
- Factors influencing frequency of maintenance; Size of filter Duty-cycle