WHAT IS SELECTIVE CATALYTIC REDUCTION (SCR)?

By Associated Petroleum Products, Inc. (APP)

 

Selective Catalytic Reduction (SCR) is one of the most cost-effective and fuel-efficient vehicle emissions control technologies available to reduce diesel engine emissions. In the trucking industry, where operations and profitability are necessary, the future is SCR. With the ability to deliver better fuel-efficiency than alternative engines using massive rates of exhaust gas recirculation (EGR), the greatest benefit of using SCR is its performance advantage. In the commercial trucking industry, including heavy and medium duty trucks, the ability to reduce emissions to near-zero levels while also delivering a 3-5% diesel fuel savings distinguishes SCR as one of the only emissions control technologies that is as good for business as it is for the environment.

The Environmental Protection Agency (EPA) has set new vehicle emissions standards which will require greater vehicle fuel-efficiency and lower emissions levels. The new standards were effective in 2009 for passenger cars and light duty trucks and in 2010 for Class 8 heavy duty commercial trucks.  To date, Selective Catalytic Reduction technology is the only vehicle emissions control technology that has been proven to be capable of meeting these standards. In heavy-duty trucks, SCR will reduce:

 • NOx emissions up to 90%
 • Hydro carbons (HC) and carbon monoxide (CO) emissions by 50–90%
 • Particulate matter (PM) emissions by 30–50% 

When the EPA 2010 emissions standards take effect, no heavy-duty diesel engine can be emitting levels of nitrogen oxide (NOx) higher than .2 g/bhp-hr (grams per brake horsepower-hour), a standard more stringent than any in place in Europe.

SCR will allow the engine to stay focused on producing efficient power and torque over a long life. By freeing the engine from emissions control responsibilities, SCR enables greater fuel-efficiencies and reduces the cost of operations.

Through today's emissions control technologies, particulate matter (PM) and nitrogen oxides (NOx) are effectively and efficiently handled without stressing the engine. That means the engine runs better, stays cleaner and lasts longer.

Optimization of the engine leads to better fuel efficiency and reduced particulate output. As a result, the diesel particulate filter (DPF) needs less active regeneration (a filter cleaning process), further enhancing fuel efficiency. Any additional NOx generated by the optimization is then efficiently and effectively handled by the SCR catalyst which reduces NOx in the exhaust stream and at the tailpipe. In this way, SCR-equipped trucks can easily achieve even the lowest emissions requirements.

In fact, it has been shown that use of SCR vehicle emissions control technology has led to certain performance benefits, including:

   • Reduced dependency on exhaust gas recirculation (EGR)

      - Engine functions and breathes more freely and efficiently

      - Less heat rejection (wasted energy)

      - Greater component reliability

   • Reduced fan on-time which leads to increased fuel economies

   • No adverse effect on oil drain or service intervals

   • Less frequent active regenerations which leads to increased fuel economies and less operational costs

Today, SCR is being adopted as an emissions control technology in developed markets including Japan, China and Australia, as well as Europe and North America.[1]

 

What is Diesel Exhaust Fluid (DEF)?

By Associated Petroleum Products, Inc. (APP)

 

 

Diesel Exhaust Fluid (DEF) is a solution made up of purified water and 32.5 percent urea that is used as a carrying agent for the ammonia needed to reduce nitrogen oxide (NOx) emissions from diesel engines into nitrogen, water and carbon dioxide (CO2).

 

How DEF works within an SCR system is to treat the exhaust gas downstream of the engine.  Small quantities of DEF are injected into the exhaust stream.  When mixed with the NOx, it changes into harmless nitrogen and water.

 

2.5 gallons of DEF will yield over 800 miles of travel. You can drive from L.A. to Boston and back on less than a single 23-gallon tank of it (estimated usage rate is approximately 2% per gallon of fuel).

 

Example of SCR Technology

 

 

DEF will freeze beginning at 11° F.  The SCR system is designed to provide heating for the tank and supply lines which will reduce the melting time for frozen DEF. If the DEF freezes when the vehicle is shut down, start up and normal operation of the vehicle will not be inhibited.  The SCR heating system is designed to quickly return the DEF to liquid form and the operation of the vehicle will not be impacted.

 

DEF is a non-toxic, non-polluting, and non-flammable substance.  Therefore, it is safe to handle and store and poses no serious risk to humans, animals, equipment, or the environment when handled properly. Storage is recommended between 10°F - 90°F.  In cold temperatures it’s recommended to store DEF in a storage unit, in warm temperatures it’s recommended to store in a shaded area.

 

Distribution of DEF exists in truck stops and some pumps nationwide.  As demand increases, availability will improve.

 

As a supplier of DEF, APP recommends purchasing in bulk totes, drums, and/or cases depending on the size of your fleet.  Since a little DEF goes a long way you should be able to service in-house most of your DEF needs.  Additionally, product integrity has never been more important than for DEF.  A dedicated stub and pump camlock is necessary to keep contaminants out.  Our pumping systems allow for an easy transition from drum to tote as your fleet grows and/or replaced with newer engines.