Emissions control systems for today’s air quality standards

FAQs – General

1. Why should I be concerned with emissions compliance?
2. What penalties am I likely to face if my equipment is not in compliance?
3. Who is legally responsible for knowing what local, regional and national regulations apply to a customer’s business?
4. Where can I find information on available incentive programs and funding?
5. What is verification?
6. What is a ceramic substrate?
7. What is a catalyst?
8. What is the difference between a diesel oxidation converter (DOC) and a diesel particulate filter (DPF)?
9. What is a three-way catalyst?
10. What is regeneration and why is it important?
11. Why is fuel sulfur content important?
12. How will I know if the fuel I am using is ultra-low sulfur diesel?
13. What is selective catalytic reduction (SCR)?

 

1. Why should I be concerned with emissions compliance?

With the U.S. EPA regulations and individual state regulations such as those put into place by the California Air Resources Board, every region of the United States is now under scrutiny for complying with higher air quality standards. The need to control emissions is also evident throughout the world as seen with the institution of the European Union Air Quality Directives, Germany’s TA Luft, and Japan’s Air Pollution Control Law. Emissions compliance not only helps reduce the toxic health and environmental effects of air pollution; it also means that a company is in adherence with the local and federal laws.

2. What penalties am I likely to face if my equipment is not in compliance?

Being noncompliant can lead to substantial fines, work stoppage and potential job loss. Site permits may also require emissions reductions. A company who fails to comply may loose new contracts, as well as available project funding.

3. Who is legally responsible for knowing what local, regional and national regulations apply to a customer’s business?

The end-user is ultimately responsible for ensuring that equipment is compliant with all state and local laws. For information on emissions regulations, you can subscribe to CleanAIR’s free Emissions and Product Guidebook for help in assisting your customers understand air quality compliance. The guidebook is available as a digital PDF document.

Click here to receive your free copy of the Emissions and Product Guidebook.

4. Where can I find information on available incentive programs and funding?

Below are links to various funding programs. You should also check with your local and state air quality agency for regional funding opportunities.

• Carl Moyer Memorial Air Quality Standards Attainment Program – Provides incentive grants for cleaner-than-required engines, equipment and other sources of pollution providing early or extra emission reductions, (California Only).
  http://www.arb.ca.gov/msprog/
  moyer/moyer.htm
• Clean Transportation – Funding from the MSRC (Mobile Source Air Pollution Reduction Review Committee)
  http://www.cleantransportationfunding.org/
• Congestion Mitigation and Air Quality (CMAQ) Improvement Program – Funding for surface transportation and other related projects that contribute to air quality improvements and reduce congestion.
  http://www.fhwa.dot.gov/
  environment/cmaqpgs/index.htm
• National Clean Diesel Campaign – available funding for clean diesel activities.
  http://www.epa.gov/diesel
• NYSERDA – New York State Energy Research and Development Authority – Current Funding Opportunities
  http://www.nyserda.org/
  funding/funding.asp?i=2
• Oregon Department of Environmental Quality, Tax Credits – Offers the Pollution Control Facilities Tax Credit Program providing tax credits for controlling, reducing or eliminating air, water, noise or nonpoint source pollution and the Clean Diesel Engine Tax Credit Program providing tax credits for purchasing clean burning engines or for repowering or retrofitting older diesel engines to reduce pollution.
  http://www.deq.state.or.us/
  msd/taxcredits/txcp.htm
• TERC – Texas Environmental Research Consortium – Commissioned to significantly improve ozone science and air quality modeling through the Air Quality Research (AQR) Program and New Technology Research and Development (NTRD) Program.
  http://www.tercairquality.org/
• TERP – Texas Emissions Reduction Plan – A comprehensive set of incentive programs aimed at improving air quality in Texas.
  http://www.tceq.state.tx.us/
  implementation/air/terp/
• West Coast Collaborative – A public-private partnership to reduce diesel emissions
  http://www.westcoastdiesel.org/

5. What is verification?

Verification is the process used to validate that retrofit products actually achieve the emissions results claimed by the manufacturers. Retrofit regulations and incentive programs generally require verified products. If a technology is CARB verified it is also considered EPA verified through a reciprocal agreement whereby EPA honors CARB verification.

6. What is a ceramic substrate?

Composed of thin-walled extruded ceramic, substrates are used as the bases to hold catalyst coatings.

Substrates used for diesel oxidation converters (DOC), three-way catalyst (TWC) and selective catalytic reduction (SCR) catalysts are “flow-through” in structure. This allows gases to pass straight through.

Substrates used for diesel particulate filters (DPF) are called “wall-through.” This structure physically traps soot because alternating channels in the substrate are blocked. Substrates can be cylindrical or square and come in many sizes.

7. What is a catalyst?

A catalyst is a substance that promotes a chemical reaction without being consumed. It also allows reactions to take place at lower exhaust temperatures. Catalysts are usually metal-based. Common metals used in catalysts production are platinum, palladium, rhodium, iron, nickel, vanadium (considered toxic), iron zeolite or copper zeolite. Two reactions are associated with catalysis: oxidation (combining molecules) or reduction (dividing molecules). Different catalyst formulations are used in order to achieve oxidation, reduction or a combination of both, resulting in the reduction of NOx, particulate matter, hydrocarbons, carbon monoxide and many other emission problems.

8. What is the difference between a diesel oxidation converter (DOC) and a diesel particulate filter (DPF)?

A DOC is classified as a flow-through emissions control unit, having large open channels that allow exhaust gases to pass through unobstructed. Emissions reduction is achieved when exhaust gases interact with the catalyst coating on the channel walls. DOCs are primarily used to reduce carbon monoxide, hydrocarbons and, to a lesser degree, PM.

A diesel particulate filter is classified as a wall-flow filter, containing alternating blocked channels that force exhaust gas through its porous walls, capturing PM. Diesel particulate filters are used for the reduction of particulate matter, carbon monoxide and hydrocarbons.

9. What is a three-way catalyst?

A three-way catalyst is used to reduce emissions from spark-ignited engines (natural gas). Utilizing the same flow-through ceramic substrate as a DOC, a three-way catalyst is coated with a unique catalyst that significantly reduces carbon monoxide, hydrocarbons and nitrogen oxides. Therefore the reduction process is called “three-way” conversion.

10. What is regeneration and why is it important?

Diesel particulate filters are efficient at collecting PM from diesel exhaust, resulting in a considerable amount of build-up within a few hours of operation. To clean the filter or reduce build-up, it is necessary to oxidize the solid carbon-based PM into gaseous carbon dioxide. This process is called regeneration. It is primarily dependent upon the type of catalyst applied to the diesel particulate filter, exhaust gas temperature and fuel sulfur content.

11. Why is fuel sulfur content important?

During the combustion process inside a diesel engine, sulfur in the fuel is oxidized into SO2. Further oxidation of SO2 to SO3 can take place over a catalyst in the exhaust stream. The SO3 combines with water to form sulfuric acid which is considered a particulate. Minimizing the oxidation of SO2 can be achieved by using the right catalyst or by reducing sulfur levels in the fuel, (using ultra-low sulfur diesel).

Successful regeneration occurs at lower exhaust temperatures when the sulfur content of fuel is decreased.

12. How will I know if the fuel I am using is ultra-low sulfur diesel?

The designations for diesel fuels as define by the American Society for Testing and Materials (ASTM) standard D975 Table 1 are:

S15 = 15 ppm maximum sulfur content (also known as ULSD)
S500 = 500 ppm maximum sulfur content (also known as LSD)
S5000 = 5,000 ppm maximum sulfur content

Values in other areas of the world may be different for ULSD. The Canadian diesel market uses the same designations of S15, S500, S5000.

13. What is selective catalytic reduction (SCR)?

Selective catalytic reduction is the process whereby a reductant such as ammonia or urea is mixed with NOx emissions then passed through a special flow-through catalyst to create a reduction process. During the process, the ammonia-NOx mixture is converted into harmless nitrogen and water. SCR catalysts can be made of either vanadium-based or iron zeolite-based. Vanadium is classified as toxic. Iron zeolite catalysts are non-toxic and considered a safer alternative for SCR systems.

 

 

 

 

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