05-13-10

Booster Fan Design was the Hot Topic on May 13, 2010

Three experts provided some unique insights into the fan considerations in a cleaner carbon constrained environment. One consideration is the increased air volume with the co-firing of biomass. Another is the impact of air pollution control equipment and carbon capture on fan needs. There is an opportunity to minimize the energy loss by taking advantage of the colder smaller air stream after the flue gas has been chilled for carbon capture by the ammonia system.

The three experts agreed that the closest that you can accurately measure volume is plus or minus two percent. This is a critical issue. If you are going to be required to remove 90 percent of the mercury, how can you even validate performance given the combination of volume, protocol gas, and analyzer inaccuracies? They all are cumulative. More important as Steve Niksa asserted in the March 25 webinar, you cannot accurately measure the inlet mercury. When you also consider that there is no good way for measuring particulate mercury, you have big uncertainties relative to control efficiency.

Jim Greenzweig, Director of Market Development and Application Engineering at FlaktWoods Americas, discussed the many choices that are available for the fan equipment required when adding a SCR /FGD/deNO_x/CC system to an existing coal-fired unit or designing a new unit. Design considerations include the following:

Required flow and pressure relationship and influence on fan selection and design.
Location of the fan in the system and influence on size, materials of construction and cost.
Spatial constraints.
Number of fans.
Expected load model for the unit.
NFPA regulations and fan control.
Future anticipated system changes and requirements.
Expectations for future spare parts and maintenance expenditures.

Dan Banyay, Director of Energy Sales and Product Development at Robinson Fans, Inc., described “The Right Way to Retrofit Fan Rotors.” System changes affect the fan requirements. Often the existing fan can be used with a rotor replacement that is more suitable for the revised performance and which can also have other benefits such as increased energy efficiency and improved mechanical reliability.

David Marshall, Vice-president of Sales at Howden Variax, Inc., discussed axial fans and how to design for high efficiency and stable operation. David indicated that axial fans downstream of the scrubber are very popular in Europe. They have to be rubber lined and are more subject to corrosion than dry fans, but the energy savings is substantial. China has also shown a preference for axial fans. In China the scrubber system can be bypassed. This lends itself to use of a separate axial fan in the bypass loop.

The Bios, Abstracts and Photos can be viewed as follows: BIOS, PHOTOS, ABSTRACTS - MAY 13, 2010.htm

The individual slides can be viewed in the FGD Decision Tree as follows:

James Greenzweig - FlaktWoods

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Scrub

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Physical

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Component Specification

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Fans