123ArticleOnline Logo
Welcome to 123ArticleOnline.com!

ALL >> Automobiles >> View Article

Combustion Fan Blowers

By Author: Oleg Tchetchel
Total Articles: 55

The amount of air required for theoretically perfect combustion is based on the portion of the combustible substances carbon (C), hydrogen (H2), oxygen (O2), and sulfur (S) contained in fuel. These are the only combustibles found in common fuels. In practice, the combustion system designer should determine the actual air volume requirements and the excess air margin based on an analysis of the fuel in question. The fan selection for the application should be capable of meeting both conditions with good efficiency, economy, and stability. Whenever possible, the actual condition should represent the most efficient point of operation for the fan selected for the application.

The combustion of coal and most fuel oils will release sulfur fumes into the flue gas. If a wet scrubbing or cleaning apparatus is used, water vapor will combine with the sulfur to form sulfuric acid. This can place severe constraints on the fan types available to handle this highly corrosive gas stream. For this very reason, flue-gas-desulfurization equipment is designed into the pollution control systems of many combustion processes. Another alternative to reduce the potential for sulfuric acid in the exhaust system is to mix lime or crushed limestone in a fluidized bed combustion process so the lime will neutralize the sulfur and stabilize the pH of the exhaust gases.

Ideally, the fan in any combustion process will supply just enough air to completely burn all the fuel, and no more. This will help keep heated, but unused, air from going up the stack. Actually, this idea is approachable with gas burners but impractical with wood- or coal-fired combustion. Thus, nearly all air volume requirements for combustion processes are calculated to include some margin of excess air. Insufficient air volume will result in wasted fuel and excessive particulate along with potentially explosive gases in the exhaust system. From this viewpoint it is better to include excess air volume.

To reduce volume and pressure to meet the actual design or reduced load conditions, inlet dampers or variable frequency drives are used. Variable speed offers the most efficient means of performance reduction, although the initial cost and equipment maintenance is greater than that of dampers. These must be evaluated on an individual job basis to determine whether the power savings will offset the greater initial price differential and added maintenance costs. The criteria for selecting the fan motor is usually specified per job. Often, the motor is sized to handle the hot operating conditions so the fan can be dampered for low load periods such as start-up or shut-down. This reduces the dampering, or turndown, range required under actual conditions.

Fans used in combustion processes, whether forced or induced draft, should be capable of meeting the following minimum requirements:

1) The fan pressure curves should be stable throughout the entire operating range of the system. Certain fans, such as most radials, pressure blowers, and airfoil fns, are stable from wide-open to completely closed-off to offer the broadest possible control range.
2) The fan and all its components should be designed to meet even the test block condition without passing through the first critical frequency of the rotating parts. A common specification calls for the fan shaft’s first critical speed to be 125% of the maximum operating speed.
3) The entire fan assembly should be rugged to withstand industrial service. Catalogs or drawings should contain complete material specifications.
4) Whenever possible the entire fan, motor, and drive assembly should be factory assembled, aligned, and test run to ensure smooth operation. The fan manufacturer should be capable of test running complete assemblies.

Induced-draft fans have further special requirements:

5) Where fan airstream temperature exceeds 300°F., the fan should include a shaft cooler and the bearing base should be separated from the fan housing.
6) The fan should be selected to handle the maximum particulate loading. Radial, radial-tip, and backwardly inclined designs in a variety of alloys are suitable to handle a wide range of contaminated airstreams.
7) Fans handling particulate-laden airstreams should be furnished with shaft seals to protect the inboard bearings. Ceramic-felt shaft seals usually provide the best protection in these applications.
8) Fans fao dirty airstreams should also be furnished with a cleanout door and a drain to facilitate periodic cleaning. Various quick-opening, bolted, and raised, bolted cleanout doors and drain connections are generally available.
9) Blade liners, housing liners, and hard surfacing of blades and/or inlet cones may be desirable, depending on the particulate loading.

Additional information can be found at the Canadian Blower company web site http://www.canadianblower.com/fans/index.html

Oleg Tchetchel
Canadian Process Air Systems Designer
oleg.tchetchel@canadablower.com
Canadian Blower
http://www.canadianblower.com/hvac/index.html
http://www.canadianblower.com/index.html

Total Views: 83Word Count: 745See All articles From Author

Automobiles Articles

1. Recognizing The Real Value Of A Student Auto Loan
Author: jeffery reynold

2. Be A Pioneer In The Motorcycle Repairs Here's What You'll Need
Author: Levi Fysh

3. Rockman – The Leading Manufacturers Of Drive Chain Kits & Alloy Wheels For Two Wheelers
Author: Rockman Industries

4. The Most Effective Method To Become An Independent Tyre Dealer
Author: My Tyre Point

5. Atv Tyres
Author: Trident

6. Destiny International Filtration - Oil Cleaning Machine Manufacturer In India
Author: priya singh

7. Wounded Warrior Project & Harley-davidson Surprise Los Angeles Veteran With New Bike As Part Of Miss
Author: 1888pressrelease

8. Vectra - The Heavy Construction & Earth Moving Equipment Manufacturing Companies In India & Europe
Author: Vectra

9. Think Long Term Before You Decide On Your Auto Loan Term
Author: Kaitlin Miller

10. Tips On Choosing The Best Car Breakers Services In Birmingham
Author: Denny Sour

11. Benefits Of Scrap Car Removal In Birmingham
Author: Alex Stewart

12. Black Car, Limousine Service And Airport Transportation West Palm Beach Fl
Author: Classlimo

13. Matters To Look Upon While Looking For A Gear Manufacturer In India
Author: SONA BLW Precision Forgings Ltd.

14. Car Detailing Tips And Keep Your Car Exterior In A Superior Condition With Autofresh
Author: neel patel

15. Things To Know About The Availability Of Different Warranty Plans For Cars
Author: Ewan Thorpe

Login To Account
Login Email:
Password:
Forgot Password?
New User?
Sign Up Newsletter
Email Address: