COMPACT SCR™ SYSTEMS

What is SCR?

Selective Catalytic Reduction (SCR) is an emissions control technique that has been used on stationary pollution sources for more than 30 years – primarily to control oxides of nitrogen (NO_x) emissions. It works by adding a small amount of a reductant chemical such as ammonia or urea to the exhaust upstream from a catalyst. The reductant reacts with the NO_x to produce harmless nitrogen gas and water. Recently, a few new heavy vehicles, such as ferryboats, have been ordered fitted with traditional SCR systems, but the size, weight, and cost of these systems have made them impractical in most mobile applications, and especially for retrofit applications.

What’s different about the EF&EE-Extengine Compact SCR™ system?

EF&EE’s Compact SCR system uses new technology originally developed in Europe to allow heavy-duty diesel truck engines to meet Euro 5 emission standards. Compared to traditional systems designed for stationary sources, Compact SCR systems are about 1/5th the size and weight, making them practical for mobile applications, even in retrofit applications where the available space is very tight.

The Compact SCR system is designed for ruggedness and reliability in vehicular use. Economies of mass production in the key components make it highly cost-effective as well. The picture at right shows a Compact SCR catalyst and urea injection system designed for a 160 to 200 horsepower truck engine.

The reductant used in the Compact SCR system is a safe, non-toxic solution of urea in water. Urea is commonly used as an agricultural fertilizer, and is even fed to cattle as a supplement. Material Safety Data Sheets for Urea are available from suppliers such as Industrial Solution Services.

In addition to reducing NO_x emissions, the Compact SCR catalyst works as a diesel oxidation catalyst, reducing emissions of diesel particulate matter (PM), toxic air contaminants, hydrocarbons, and odor.

How effective is the Compact SCR™ system?

At 25% engine load and higher, the Compact SCR system is typically 85 to 95% efficient for NO_x emissions and 30 to 60% efficient for diesel PM, depending on PM characteristics. The graphs and table below show test results for a Compact SCR system on a 475 horsepower DDC Series 60 marine engine. The SCR reactor was 36” x 34” x 17”, and the whole system weighed less than 300lbs (136kg).

Won’t SCR take up a lot of space?

Other SCR systems now on the market are based on technology originally developed for large, stationary power plants. Compared to these systems, EF&EE’s Compact SCR technology requires about 1/5th to 1/10th of the space – only a little more than the existing silencer. For example, the SCR converter in for a pending order for a 1400 horsepower fast ferryboat, pictured at right, will be slightly under 8’ by 4’ by 17 inches thick, and will weigh only 650lbs (295kg). In most cases, Compact SCR systems can be retrofit to existing vehicles without significant structural change.

Why should I consider installing Compact SCR™ systems on my engines?

Installing Compact SCR systems on your engines will reduce the exposure to diesel pollutants by your customers, employees, and neighbors, reducing the chance of lawsuits. It will contribute to your overall image of environmental responsibility. A “green” image is increasingly important in seeking business from governments and environmentally-conscious corporations, and a commitment to the reduction of diesel emissions will help to ensure the continued growth of your company and industry.

Increasingly, companies in industries such as marine construction, offshore oil projects, freight transportation, and others are being required to offset the emissions produced by their vehicle fleets. In these cases, the cost to offset the NO_x emissions from an engine can be many times higher than the cost of the fuel it burns. Compact SCR will reduce the amount of offsets needed by 85 to 95% – saving your customers money and increasing the value of your services. In some cases, you may even be able to generate emission offsets or mobile-source emission reduction credits (MERCs) for sale, or for use by other parts of your company to offset emissions from stationary sources.

What are my options for Compact SCR™ systems?

EF&EE offers a range of standard catalyst mount configurations, with matching dosing units, suitable for different engine sizes and duty cycles. This line includes the eight catalyst model pictured above, as well as models containing one, two, four, and six catalysts. An 18-catalyst model is under development for locomotive engines. In addition to our standard models, we can design and build custom SCR systems to fit almost any mobile engine. We are also presently developing designs which incorporate Diesel Particulate Filters (DPF) into our catalyst mount configurations. For more information, please contact Mr. Christopher Weaver.