Fabric and Fabric Filter Bag Testing Case Studies

Testing Case Studies

Steel Plant Electric Arc Furnace
Fabric Testing to Assist in Making Purchase

Electric Utility Reverse Air Baghouse
Fabric Testing to Assist in Making Purchasing Decisions

Molecular Sieve Supplier
Using Baghouse Filtration Products (BFP) Verification Testing to Accelerate Permit Process

Utility Plant in Southeastern United States
Develop Fabric/Bag Quality Assurance Plan and Assist Client in Implementing the Plan

East Coast Based Utility
Develop Fabric/Bag Quality Assurance (QA) Plan, Conduct (QA) Testing, and Develop and Implement Long Term Bag Monitoring Program

Union Chemical Division of Union Oil
Improvement of Baghouse Performance

USEPA/IERL, Research Triangle Park, NC
Full Scale Demonstration of a High Velocity Fabric Filter
System Used to Control Flyash

Lonestar Steel Co.
BPMES Installation

Ironton Iron
Pilot Evaluation of an Iron Foundry

Baltimore Gas & Electric - Crane Station
BPMES Custom Modification

 

Fabric Testing to Assist in Making Purchase

Client      Steel Plant Electric Arc Furnace Baghouse
Description      
The EPA Environmental Technology Verification (ETV) program was established to verify the performance of environmental technologies using certified testing protocol.  The ETV Baghouse Filtration Products (BFP) was set up to verify the performance of filtration fabrics.  Testing is conducted in accordance with a verification protocol for testing filtration efficiency with emphasis on filtration efficiency for particles 2.5 microns or smaller.  Total removal efficiency and pressure drop data are also reported.

Purchasers of fabric filter baghouses and fabric filter bags who are aware of the BFP verification program have appreciated the credible and high-quality performance information that is generated by the program.  ETS is the only laboratory approved for filtration product testing within the EPA ETV Program.  To date there have been several reported cases where fabric filter operators have used the information gleaned from verification statements and their accompanying reports to assist them in their filter media purchasing decisions.

A U.S. based steel producer was replacing the fabric filter bag set from a reverse-air baghouse serving its electric arc furnace.  The baghouse contained more than 2,000 bags and was treating approximately 14,000 m3/min. (500,000 ft3/min.) of flue gas.  The purchaser was deciding between either a non-membrane or membrane filter fabric.  In this case the purchaser selected the membrane filter fabric because the verification test data indicated that the membrane offered lower operating pressure drop and minimized the potential for process upsets than would the non-membrane fabric.  The lower pressure drop offered a savings of $20,000/cm w.g. ($50,000/in. w.g.).  This savings resulted in a lower total cost of compliance for the membrane fabric, in spite of its higher purchase price when compared with the non-membrane fabric.


Fabric Testing to Assist in Making Purchasing Decisions

Client      Electric Utility Reverse Air Baghouse
Description      
The EPA Environmental Technology Verification (ETV) program was established to verify the performance of environmental technologies using certified testing protocol.  The ETV Baghouse Filtration Products (BFP) was set up to verify the performance of filtration fabrics.  Testing is conducted in accordance with a verification protocol for testing filtration efficiency with emphasis on filtration efficiency for particles 2.5 microns or smaller.  Total removal efficiency and pressure drop data are also reported.

Purchasers of fabric filter baghouses and fabric filter bags who are aware of the BFP verification program have appreciated the credible and high-quality performance information that is generated by the program.  ETS is the only laboratory approved for filtration product testing within the EPA ETV Program.  To date there have been several reported cases where fabric filter operators have used the information gleaned from verification statements and their accompanying reports to assist them in their filter media purchasing decisions.

An electric utility used the ETV test data for guidance in replacing 9,000 fabric filter bags in its reverse-air baghouse. The baghouse contained over 9,000 bags treating 68,000 m3/min. (2,400,000 ft3/min.) of flue gas from a coal-fired boiler.  The utility's procurement budget was well over $1,000,000.  An evaluation of viable filter fabric candidates resulted in a short list of two filter fabrics.  Both filter fabrics had membranes.  The facility used the ETV data to identify differences in emissions and pressure drop performance between the competing membrane fabrics, and ultimately selected an ETV-verified media based on the verification data.  A representative of the company supplying the selected membrane stated that "the verification test report demonstrated that membrane fabric is a viable means to lower pressure drop and that all generic membranes are not the same."


Using Bag Filtration Products (BFP) Verification Testing to Accelerate Permit Process

 

Client      Molecular Sieve Supplier
Description       
The EPA Environmental Technology Verification (ETV) program was established to verify the performance of environmental technologies using certified testing protocol.  The ETV Baghouse Filtration Products (BFP) was set up to verify the performance of filtration fabrics.  Testing is conducted in accordance with a verification protocol for testing filtration efficiency with emphasis on filtration efficiency for particles 2.5 microns or smaller.  Total removal efficiency and pressure drop data are also reported.

Purchasers of fabric filter baghouses and fabric filter bags who are aware of the BFP verification program have appreciated the credible and high-quality performance information that is generated by the program.  ETS is the only laboratory approved for filtration product testing within the EPA ETV Program.

In addition to being a valuable marketing tool for vendors and informational resource for fabric filter operators making purchasing decisions, the BFP verification program provides federal, state, and local regulators with improved ability to make informed decisions.  In providing access to credible and objective performance test data, the BFP verification statements provide the regulators with a demonstrated technology basis for streamlining the permitting process and compliance testing requirements.  The California South Coast Air Quality Management District (SCAQMD) has recently adopted a rule (Rule 1156) that provides incentives for cement manufacturing facilities to use ETV-verified baghouse filter fabrics to control particulate emissions.  By reducing the required compliance testing frequency from annual to every five years, this rule can provide significant cost savings to users of verified technologies (SCAQMD, 2005, Pham, 2006).

Recognizing the importance of having a global standard for fabric filter media testing, the ASTM has adopted the ETV Baghouse Filtration Products testing protocol as the basis for its standard (ASTM D6830-02) promoting standardization and consistency in performance evaluation for these technologies.  The International Standards Organization (ISO), a worldwide voluntary standards organization, has also proposed ETV testing protocol as their standard.

A major supplier of molecular sieve adsorbents, with facilities in Europe and the United States, was in the process of revising the operating permit at its Louisville, Kentucky plant.  The facility operates about 25 baghouses on a variety of process operations, including a number of high temperature (greater than 300į F) applications.  In an effort to streamline the permitting process, the company requested that the Kentucky Department of Environmental Quality (KYDEQ) consider verification test data from the ETV program in lieu of compliance testing.  The agency agreed to this request with the provision that additional tests be conducted using the ETV and ASTM test protocols.  These additional tests were to be conducted using test dusts that were actual process dusts extracted from the applications identified in the revised permit application.  Tests were conducted on three different dusts.  Three fabrics supplied by BWF-America were tested; a 22-ounce polyester felt fabric with a singed collection side, a specialty aramid felt fabric crafted of micro-denier fibers and an enhanced scrim (the same construction as the BWF polyester material that was tested and verified by EPA/ETV in June, 2002), and a P84 felt fabric with a finish treatment for improved dust cake release.

Testing was conducted in accordance with ASTM 6830-02 with test specifications and conditions as detailed in the Generic Verification Protocol (GVP) for Baghouse Filtration Products developed by the ETV Air Pollution Control Technology (APCT) Center, operated by RTI International under a cooperative agreement with the EPA's National Risk Management Research Laboratory.  Because of time constraints and the limited quantity of test dust available, testing was limited to one test run per fabric/dust combination.  The test results showed that outlet (exiting the tested filter fabric) emission levels were extremely low for both total mass particulates and PM 2.5 and were significantly below regulated levels set by the agency.  These very favorable results were achieved for all filter fabric/dust combinations and were consistent with the results of the verification tests as reported in the June, 2002 Verification Statement for "BWF America's Grade 700 MPS Polyester Felt".  The KYDEQ considered the ETV data along with the results of the additional filter fabric testing when reviewing the permit application.  Furthermore, the agency accepted the data as a substitute for compliance tests and subsequently granted the revised permit.  It is estimated that the acceptance of the ETV data (in lieu of compliance tests) significantly reduced the time and cost of the permitting process.  Clint Scoble, president of BWF-America at the time, stated "the customer made the permitting process easier by running our materials through the ETV testing process".


Develop Filter Fabric/Bag Quality Assurance Plan and Assist Client in Implementing the Plan

 

Client      Utility Plant in Southeastern United States
Description       
ETS was hired by an electrical power producer to define the procedures and acceptance criteria used to sample and release filter fabric, sewing thread, and fabric filter bags to be manufactured for the clients' power generating facility in South Carolina.  Prior to developing the QA document, ETS had developed a bag drawing that included all material, hardware, and fabrication specifications.  The drawing package also included minimal acceptance levels of the filter fabric for permeability, tensile strength, flex strength, and burst strength.

 

The plan called for all fabric roll cases to be inspected to insure roll number, lot number, and certifications were in agreement.  A sequential list of fabric roll numbers defining their order through the finish lot process was developed and roll numbers to be sampled identified.  The group of fabric rolls for the subject fabric filter bag set were tagged and separated from other stock.  Three levels of fabric testing were performed, with the highest percentage of stock being tested in Level III.  In all there were 18 different parameters tested.  Sewing thread was inspected for organic content (Loss on Ignition), breaking strength, ply quantity, and yarn designation.

 

After the lots were approved, filter bag fabrication was initiated.  The plan called for two bags from each lot of 100 fabric filter bags to be tested for compliance to the ETS bag drawing and for the following specifications: length and width of filter bag, filter bag to cage fit, filter bag to tubesheet fit, and defects in the workmanship of the filter bag or fabric.  The plan stated that if either of the two fabric filter bags out of a lot of 100 bags failed any inspection criteria, additional fabric filter bags from the same lot of 100 would be inspected for that failure mode.  If additional filter fabric or filter bag failures were found,  100% of the lot of 100 filter bags would be inspected.  All rejects were to be either repaired or discarded.  Specifications were also included for the packaging, handling, and storage of the fabric filter bags that passed the acceptance criteria.  The client embraced the plan, presented it to the fabric filter bag supplier and arranged for ETS to commence QA testing.

For more information about ETS' QA/QC programs click here.


Develop Filter Fabric/Bag Quality Assurance (QA) Plan, Conduct (QA) Testing, and Develop and Implement Long Term Bag Monitoring Program

Client      East Coast Based Utility
Description      
ETS developed and implemented a plan to assure the quality of fabric filter bags being procured conformed to an east coast based utility's material and construction specification.  There were two reverse-air baghouses at the facility, each baghouse contained 5,400 bags.  The plant was located in a major metropolitan area on the east coast and long term performance and reliability of the fabric filter bag set was of paramount concern.  The Quality Assurance (QA) Manual defined the procedures and acceptance criteria used to sample and release filter fabric, sewing thread, filter bags and related hardware.  In total over 73,000 linear yards of fabric were used to fabricate the bags.  Prior to developing the QA document, ETS had developed a bag drawing that included all material, hardware, and fabrication specifications.  The QA Manual included minimal acceptance levels for fabric construction, thickness, weight, water repellency, organic content (Loss on Ignition), permeability, tensile strength, flex strength, burst strength, and acid resistance.  The plan also provided minimum acceptance levels for several thread parameters including break strength, organic content, yarn designation, and ply quantity.  Bag hardware such as anti-collapse rings, caps, and bands were tested and inspected for conformance to specification and quality of construction.

The plan called for all fabric roll cases to be inspected to insure roll number, lot number, and certifications were in agreement.  A sequential list of roll numbers defining their order through the finish lot process was developed and roll numbers to be sampled identified.  The group of fabric rolls for the subject filter bag set were tagged and separated from other stock.  Three levels of fabric testing were to be performed, with the highest percentage of stock being tested in Level III.  In all there were 18 different parameters tested.  After the fabric lots were approved, bag fabrication was initiated.  The plan called for two filter bags from each lot of 100 bags to be tested for compliance to the ETS bag drawing and for the following specifications: length and width of filter bag, length under tension, anti-collapse ring alignment and spacing, orientation of cap to bag seam, and defects in the workmanship or fabric.  The plan stated that if either of the two fabric filter bags out of a lot of 100 bags failed any inspection criteria, additional bags from that same lot of 100 would be inspected for that failure mode.  If additional failures were found, 100% of the lot of 100 would be inspected.  All rejects were to be either repaired or discarded.  Specifications were also included for the packaging, handling, and storage of the fabric filter bags that passed the acceptance criteria.

The bag monitoring program was conceived to determine the strength and flow characteristics of the bag set with on-stream (in service) time.  As baghouse availability is always an issue in power generation, the reliability of the bag set was a major concern of the client.  It was thought that this program would provide input in determining the useful life of the fabric filter bags, thus enabling the facility to conduct future bag set replacements during scheduled outages of the generating unit.  The program called for representative filter bags to be removed from the baghouses every six months and sent to ETS for comparative testing with the new bag specifications.  Typically a new fabric filter bag set will show a marked decrease in tested performance levels after the first few months of service time, after which the results level out and remain well above the failure plateau for a long period of time before experiencing another significant decline that approaches a level that would jeopardize the integrity of the bag set.  

The QA program was first instituted in 1986 and the fabric filter bag sets were installed in 1987.  The filter bag monitoring program was instituted shortly thereafter and continued until it was determined that the bags had reached the end of their usefulness in 2000 and replacement was called for.  The replacement fabric filter bags were subjected to the same rigorous QA program, and since their installation have continued to be monitored by ETS.  Both the QA and bag monitoring programs have been considered successes by the client in that he was insured of receiving  a high quality product that exceeded his bag life expectations, the filter bag monitoring testing determined when replacement was needed and the facility was able to schedule the change-out in a manner that didnít impact on their ability to produce electricity.

For more information about ETS' QA/QC programs click here.


Improvement of Baghouse Performance

Client      Union Chemical Division of Union Oil
Description      
Union Chemical Division of Union Oil retained ETS to improve the performance of a baghouse servicing a waste heat boiler with the problem of premature bag failure and high emission rates. An investigative program was initiated to determine the cause of the extremely premature failure. Operation and maintenance procedures were reviewed, process and flue gas parameters were monitored and documented, ash samples were analyzed and further analysis of the used fabric was conducted. It was determined that the process produced a highly corrosive material which, when introduced to the fabric, would quickly degrade the finish of that fabric. Once the finish was degraded, the bags would then abrade rapidly to deterioration. A scanning electron microscope (SEM), along with the other physical tests, provided excellent commentary on the rate of deterioration with on-stream time. A program was implemented to screen alternative fabrics for this application. Six candidates were selected and installed in the baghouse and subjected to normal operating conditions. The candidate bags were extracted periodically, tested and their results compared. From the screening program, a fabric was identified that would operate reliably in this most severe atmosphere. Bag life has been improved from a matter of months to over a year.


Full-Scale Demonstration of a High-Velocity Fabric Filter System Used to Control Fly Ash

Client      USEPA/IERL
Description      
A full-scale investigation was conducted (following a pilot plant study) of applying high-velocity fabric filters to a coal-fired boiler for fly ash control. Two filter systems (using different filter media) were installed separately on two 60,000 lb steam/hr coal-fired boilers. The performance of the fabric filters was evaluated over a one-year period to determine total mass removal efficiencies and fractional efficiencies.


BPMES Installation

Client      Lonestar Steel Co.
Description      
Lonestar Steel had just purchased a used reverse air baghouse and was in need of an instrumentation system that would fit this application. In addition to monitoring standard baghouse parameters, they wanted to be able to track other process-related parameters and have real-time alarms warn them if any parameter exceeded certain set-points. Based on its capabilities and competitive pricing, Lonestar Steel chose the BPMES. The real-time alarm feature was added to fit their needs and serves as a general upgrade to be available for future BPM systems. The Lonestar Steel BPM system was configured as a standard Model V. By using their own PC and by using a direct, PC-to-BPM connection, Lonestar was able to keep instrumentation costs to a minimum.


Pilot Evaluation of an Iron Foundry

Client      Ironton Iron (Intermet Foundries, Inc.)
Description      
ETS was contracted to identify and evaluate technically feasible technologies for control of visible emissions consisting of particulate and condensible organic compounds from a cooling process at an iron facility. The multiple-pollutant nature of this emission stream raised concerns with each available particulate control as well as with each organic control technology. Although technologies exist for each of these two types of emissions individually, there is not single conventional technology capable of treating both types collectively. Having exhausted conventional control options, our study led us to consideration of an emerging control technology using carbon injection with a baghouse. This consideration was reinforced when it was learned a similar emission stream was causing operating problems with a baghouse from condensation of the organics.

A four-week pilot evaluation was conducted using a dry-injection feeder and baghouse treating a similar emission stream. The BPMES was used to monitor, collect, and organize baghouse performance data. Commercially available bag precoat material and powdered-activated carbon were injected over a range of feed rates. Although both types of injected material resolved the condensation problem with the baghouse, the use of carbon completely eliminated the visible emissions. Foundry personnel continue to use the lower-cost precoat material to solve the condensation problem while saving more than $100,000 per year in maintenance costs. The regulatory agency is reviewing the need to require carbon-injection for further control of the organics.


BPMES Custom Modification

Client      Baltimore Gas & Electric - Crane Station
Description      
The Crane Station Baltimore Gas and Electric (BG&E) power plant has been using two ETS patented Baghouse Performance Monitors to monitor their large reverse-air baghouses since the late 1980s. Although the existing BPMES "stepping modes" were generally adequate for most monitoring needs, the plant engineer had started to rely on the BPM's capability to follow and monitor the cleaning cycle from compartment to compartment. Unfortunately, this capability relied on tubesheet pressure drop signals as feedback to determine when a particular compartment is cleaning, and if any compartments were ever put off-line, the BPMES could be "confused". In early 1993 the plant engineer decided to eliminate this problem, and he contracted ETS to make the appropriate modifications. The resulting changes now allow the system to correctly follow the cleaning cycle and to identify (by number) exactly which compartment is being cleaned, and which compartments are off-line. BG&E can now use feedback from damper actuators rather than pressure signals to intelligently follow the cleaning cycle. This new mode of operation can now be made available to future BPMES customers as a standard option.

 

Copyright © 1999, ETS Incorporated



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