1. New Trends in Fabric
Filter Technologies
RICH MILLER
SR. CONSULTANT AND PRINCIPAL
MILLER ENERGY & ENVIRONMENTAL SERVICES, LLC
ETS FABRIC FILTER SEMINAR
MAY 4TH AND 5TH, 2016
2. Objectives
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Objectives of this presentation
• Fabric and filter bags design options available for power generation pulse jet fabric filters
• Discussion on use and benefits of expanded surface area filter bag designs for enhancing existing
fabric filter operation
• Benefits of fabric filter optimization as a means of reducing ACI and other dry sorbents injection rates
and cost while still maintaining current Utility and Boiler MACT limits
3. Past Pulse Jet Fabrics
In the past, a limited number of fabrics were utilized on pulse jet fabric filters. Some were carry
overs from reverse gas FF type collectors. These included some of the following:
• Woven fiberglass fabrics
• Both light weight and heavy weight fabrics
• Various weaves and coatings
• PTFE membrane coated fiberglass (Still utilized)
• Heavy Weight PPS (Ryton) Fabrics with large (7-denier) fibers on PTFE Scrim (most currently
utilize finer denier fibers – 2.2 to 2.7 denier standard with some utilizing even finer fibers or
combination)
• In some cases, Aramids (Nomex) fabrics were used on CFB boiler designs
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4. SO WHAT CHANGES IS INDUSTRY DEVELOPING
TO FURTHER THE DEVELOPMENT OF FABRICS
TO MEET TODAY AND TOMORROW’S NEEDS
AND REGULATIONS?
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5. Newer Developments in Fabric Filtration
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Current developments in fabrics and fibers based on worldwide coal-fired boiler operating
experience included some of the following ideas
Emerging Trends Product Approach
High efficiency filtration with
stratified fabrics of multi-lobal fibres
PPS inner web with multi-lobal P84 fiber in the
face (top cap) to lower emissions and reduce
pressure drop, lowering operating costs and
lengthening bag life
Fabrics for aggressive acid and non-
agglomerating ash and high velocity
dusts
Use of PTFE fiber blended with PPS to resist acid
degradation and minimise impact of poor dust
cake formation
Extended surface area bags to lower
emissions with lower differential
pressure and increased flows
Extended surface area bags achieve reduced
emissions from reduced pulse frequency (Solaft’s
StarBag)
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6. Use of Expanded Surface Area Bags (StarBagsTM) in Power Generation
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• The expanded surface area bags provides clients with a unique solution replacing standard filter bags without any expansion
or change to the design of existing bag houses other than a change to the supporting cages
• Some of these benefits may include:
• Reduced particulate, Hg and Acid Gas emissions
• Reduced DSI sorbents and activated carbon usage
• Increased full-load generation where high pressure drops may be limiting full-load operation
• Compliance with MATS and Plant Operating licenses
• Elimination of abrasion and early bag failures due to high velocities and filtration rates
• The expanded surface area bag alternative deliver these benefits by significantly increasing filtration area (lower A/C Ratios),
thus enabling an increase in particulate loadings, greater residence time across the filter cake, while at the same time
reducing differential pressure
With StarBagsTM, power plants can achieve lower filtration rates (A/C Ratios), lower pressure drops,
reduced particulate emissions and lower their usage of activated carbon and other DSI sorbents
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Benefits of fabric filter optimization as a
means of reducing activated carbon and DSI
injection rates and cost while still maintaining
current mercury MATS limits
9. When considering ways to optimize both the ACI injection and fabric filter
particulate control operating systems designed to meet Hg MATS compliance
requirements for EGU coal-fired boilers, one must consider the following:
◦ The impact of operating temperatures and fabric filter cleaning frequencies on both mercury
capture and sorbent feed rates, as well as operating pressure drops
◦ Types of carbons being utilized (Treated or non treated, particle size, etc.)
◦ Benefits of combining Hg CEMS monitoring output data as part of an integrated feed
forward/feedback, ACI system control logic technology
◦ Economic choices when looking at DSI injection rates to reduce SO3 levels at ACI injection
points vs. Activated Carbon Injection rates when achieving required emission limits.
◦ Lower SO3 relates to reduce demand on Activated Carbon to achieve Hg emission levels
10. 0
0.5
1
1.5
2
2.5
3
3.5
4
225 235 245 255 265 275 285 295 305 315
TotalHg(µg/m3)
Baghouse Temp (F)
Impact of Operating Temperatures
(FF on PRB-fired Boiler with PAC Injection)
• Hg observed to increase at higher BH temperatures, suggesting
Hg release as maximum “capacity” decreases
11. Case Study – Mid-West Utility
(PRB Coal)
• Baghouse was installed downstream of ESP (TOXECON) & originally sized
for future CDS Scrubber
• Operation included very low air-to-cloth ratios and long dwell times
between cleaning of the bags due to low filter cake pressure drops
• Activated carbon sat on the bags for extended time periods and was highly
saturated with Hg
• When loads caused flue gas temperatures to increase above 370F, Hg was
released from carbon, requiring higher PAC feed rates to maintain required
Hg levels
12. Solution
• Isolated FF compartments to force A/C ratio higher and cleaning cycles to increase, resulting
in a thinner filter cake with fresh PAC present.
• As a result, FF was able to maintain required mercury emissions with significantly lower PAC
injection rates
13. Summary
• Fabrics of all types have evolved over the years designed to serve both reverse gas and pulse
jet fabric filters
• A new generation of fabrics and filter bag types (StarBags) are now being offered, to enable
pulse jet fabric filters to meet today’s and tomorrows regulations while operating under a
wide range of operating conditions and coal types
• There are many benefits of optimizing both the fabric filter and ACI/DSI injection system
operation to meet MATS compliance as a marriage between control technologies
• Higher operating temperatures may require more aggressive FF cleaning frequencies and
intensities to produce a thinner, more carbon rich filter cake to achieve higher Hg reduction
levels
• Implementation of feed forward/feed back controls tied to Hg CEMS for trim control in fabric
filters has been demonstrated as a means to reduce PAC demands while achieving required
Hg control levels over a wide range of operating conditions and loads
