What Is SCR On A Diesel?

SCR is a proven and advanced active emissions control technology system that injects a liquid-reductant agent into the exhaust stream of a diesel engine using a specific catalyst. Automotive-grade urea, often known as Diesel Exhaust Fluid, is commonly used as a reductant (DEF). The DEF initiates a chemical reaction that transforms nitrogen oxides to nitrogen, water, and trace amounts of carbon dioxide (CO2), which is then ejected through the vehicle tailpipe.

What does a SCR do for diesel engines?

SCR (Selective Catalytic Reduction) systems are used to minimize dangerous Nitrous Oxide (NOx) emissions from diesel cars. It works by pumping automotive-grade urea, or Diesel Exhaust Fluid (DEF), into the exhaust stream of a diesel engine through a specifically designed catalyst.

The NOx is converted to nitrogen, water, and very minute amounts of CO2 through a chemical process triggered by the Diesel Exhaust Fluid. SCR technology can reduce NOx emissions by up to 90%.

Can an SCR catalyst be cleaned?

To eliminate impurities and blockages, SCR catalyst systems must be cleaned. Ammonia slide happens when the catalyst is not kept clean and the ammonia injection mechanism is not tuned. Because of the impurities in the fuel and the ammonia slip, ammonia salts can accumulate downstream and plate out or deposit onto the gas side of the fin tubes, lowering heat transfer efficiency and encouraging corrosion on the HRSG’s back end.

Traditional cleaning methods aren’t particularly effective or safe to use because catalyst systems can include dangerous impurities.

The use of dry ice blasting offers a safe, convenient, and environmentally responsible cleaning process from start to finish. This procedure will help to reduce the production of plugs while also extending the life of your system.

What is SCR delete?

One of the best things you can do to extend the life of your diesel pickup truck is to eliminate the SCR system. Improve the Ford Powerstroke, Ram Cummins, and GM Duramax’s durability and dependability by removing one of the weakest connections. By removing the SCR, you will no longer need to use Diesel Exhaust Fluid (DEF). The SCR and DPF must both be eliminated at the same time, and this must be done using a DPF delete tuner.

What causes SCR to fail?

It’s worth noting that the vast majority of SCR-related problems on the S611/S801+/S811+ soft starts are really caused by a soft starter-to-motor disconnect. Check the connections to the soft starter and motor, as well as any disconnects, fuses, and junctions on that line.

SCR failures in the controller can be caused by three different things, according to my experience:

Failure can occur as a result of exceeding duty cycle limits, such as starting too frequently without sufficient elapsed time between starts.

Allowing the Soft Starter to generate high current for an extended period of time will raise the temperature, causing SCR degradation and eventual failure (elevated heat reduces the reverse blocking capability of the devices and they fail).

If it’s been subjected to transitory spikes, too. SCR failure can also be caused by these transitory surges.

Finally, failure can be caused by a defective or intermittently defective motor (i.e., stator winding shorts or grounds).

How long does a SCR catalyst last?

The binding of the catalyst by fly ash from the fuel combustion is another operational challenge in coal-fired boilers. To avoid plugging by fly ash, sootblowers, sonic horns, and careful design of the ductwork and catalyst materials are required. In coal-fired power plants, SCR catalysts have a median operational lifetime of 16,000–40,000 hours (1.8–4.5 years) depending on flue gas composition, and up to 80,000 hours (9 years) in cleaner gas-fired power plants.

To extend the life of the catalyst, pollutants, sulfur compounds, and fly ash can all be removed by adding scrubbers before the SCR system, while most plants’ scrubbers are installed after the system for thermal energy transfer reasons.

How is SCR diagnosed?

  • Connect the ohmmeter’s positive output lead to the anode and the negative lead to the cathode to test the SCR.
  • Conduction may halt or continue when the gate lead is removed from the anode, depending on whether the ohmmeter is supplying enough current to keep the device over its holding current level.
  • The SCR is shorted if the ohmmeter displays continuity via the SCR before the gate is touched to the anode.
  • If the ohmmeter does not show continuity via the SCR when the gate is touched to the anode, that means the SCR is open.

What does SCR mean in power generation?

The catalyst is the fundamental component of the selective catalytic reduction (SCR) system, which eliminates nitrogen oxides (NOx) from flue gas generated by power plant boilers and other combustion sources.