Live support chatNOX Reduction, Selective Catalytic (and Non-Catalytic) Reduction Systems (SCR and SNCR)
In NOX Reduction, Selective Catalytic (and Non-Catalytic) Reduction Systems (SCR and SNCR), you'll learn ...
- NOX formation and importance of NOX emission control
- Techniques to control NOX emission by reducing NOX generation during combustion as well as those used to covert NOX to environmentally friendly species after generation
- Selective Non-catalytic Reduction (SNCR) Systems for post-combustion NOX reduction
- Selective Catalytic Reduction (SCR) Systems for post-combustion NOX reduction
Overview
Preview a portion of this course before purchasing it.
Credit: 3 PDH
Length: 33 pages
NOX (a group of highly reactive gases) form when fuels are burned at high temperatures. The two major sources of NOX generation are transportation vehicles and stationary combustion sources such as electric utility and industrial boilers. NOX has great health impacts, as well as environmental and agricultural impacts. Thus, NOX emissions have been regulated by the US states and federal authorities, as well as by most developed countries.
NOX emissions have become an important factor in the design and operation of fossil fuel burning equipment. Two techniques are normally adopted for controlling/minimizing NOX emissions from the combustion sources. First, is to minimize the NOX formation by influencing the combustion process in the combustion regions. The second approach relies on chemically converting NOX emission, after its formation during the combustion process.
The first approach, which is based on design modifications to reduce NOX formation (usually <30%) during the combustion process, burning low nitrogen fuels and reducing combustion temperature and excess air will reduce NOX generation during combustion. In the second approach, additional systems/equipment are installed to convert NOX into environmentally friendly species.
Post-combustion NOX reduction techniques (the second approach), usually used for high-level NOX reduction, are the main focus of this course. SNCR (selective non-catalytic reduction) and SCR (selective catalytic reduction) are discussed in detail, and their costs and NOX removal capabilities are compared.
The SNCR process takes place in the boiler, immediately downstream of the combustion zone, where the flue gas temperature is high enough for the process to occur. Ammonia or urea is injected into the flue gas through multiple points, to react with NOX, producing N2 and water. Effects of temperature, residence time, reducing reagent, and inlet NOX and reagent concentrations on the SNCR performance are discussed.
SCR systems, with 90% removal rate, are the best choice for large scale NOX reduction applications. In SCR, ammonia is blended and mixed with the NOX containing hot flue gas leaving the boiler. The mixture will then flow through one or more layer(s) of catalysts. NOX will react with ammonia, producing N2 and water.
Specific Knowledge or Skill Obtained
This course teaches the following specific knowledge and skills:
- Ground level Ozone (smog), its impacts, and the role of NOX in smog formation
- Thermal and fuel NOX, and ways to reduce NOX by impacting the combustion process
- SNCR and SCR systems, their differences, and how they compare for their NOX removal capabilities, and costs
- SNCR, where is installed, and what are the parameters impacting its performance
- SCR, installation locations (advantages and disadvantages), design factors (catalyst types, reactor design, catalyst activity, catalyst pitch), process chemistry (effects of: NOX and NH3 concentrations, temperature, oxygen, SO2 to SO3 oxidation, ash, poisoning, reagent utilization), SCR components (catalyst, reactor, ash handling, ammonia injection grid)
- SCR operation at reduced load
- SCR operation and maintenance: what causes the catalyst layers to degrade/lose activity, O&M cost elements, catalyst management, catalyst layer options (new, rejuvenated, and regenerated)
- SCR performance monitoring
- SCR catalyst side effect: mercury oxidation
- Typical installation and O&M costs
Certificate of Completion
You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 15 questions. PDH credits are not awarded until the course is completed and quiz is passed.
| This course is applicable to professional engineers in: | ||
| Alabama (P.E.) | Alaska (P.E.) | Arkansas (P.E.) |
| Delaware (P.E.) | District of Columbia (P.E.) | Florida (P.E. Area of Practice) |
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| Maine (P.E.) | Maryland (P.E.) | Michigan (P.E.) |
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| Wisconsin (P.E.) | Wyoming (P.E.) | |
Preview a portion of this course before purchasing it.
Credit: 3 PDH
Length: 33 pages
