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.
Learning Objectives
Upon completion of this course, participants will be able to:
- Explain ground-level ozone (smog), its impacts, and the role of NOX in smog formation.
- Distinguish between thermal and fuel NOX and describe combustion-process approaches for reducing NOX.
- Compare selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) systems based on their NOX removal capabilities and costs.
- Explain where SNCR is installed and identify the parameters that affect its performance.
- Describe SCR installation locations, design factors, process chemistry, including the effects of NOX and NH3 concentrations, temperature, oxygen, SO2-to-SO3 oxidation, ash, poisoning, and reagent utilization, and the principal SCR components.
- Explain SCR operation at reduced load.
- Describe SCR operation and maintenance, including catalyst degradation, O&M cost elements, catalyst management, and catalyst-layer options.
- Explain methods for monitoring SCR performance.
- Describe mercury oxidation as a side effect of SCR catalysts.
- Identify typical SCR 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) |
| Georgia (P.E.) | Idaho (P.E.) | Illinois (P.E.) |
| Illinois (S.E.) | Indiana (P.E.) | Iowa (P.E.) |
| Kansas (P.E.) | Kentucky (P.E.) | Louisiana (P.E.) |
| Maine (P.E.) | Maryland (P.E.) | Michigan (P.E.) |
| Minnesota (P.E.) | Mississippi (P.E.) | Missouri (P.E.) |
| Montana (P.E.) | Nebraska (P.E.) | Nevada (P.E.) |
| New Hampshire (P.E.) | New Jersey (P.E.) | New Mexico (P.E.) |
| New York (P.E.) | North Carolina (P.E.) | North Dakota (P.E.) |
| Ohio (P.E. Self-Paced) | Oklahoma (P.E.) | Oregon (P.E.) |
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| Tennessee (P.E.) | Texas (P.E.) | Utah (P.E.) |
| Vermont (P.E.) | Virginia (P.E.) | West Virginia (P.E.) |
| Wisconsin (P.E.) | Wyoming (P.E.) | |
Preview a portion of this course before purchasing it.
Credit: 3 PDH
Length: 33 pages
