Industrial Air Permits – New Clean Air Regulations and Baghouses

pollution

Previous Baghouse.com Articles on Air Permitting:

By Dominick DalSanto

October 3, 2012 – Baghouse.com | Recently, the EPA has been busy issuing new air pollution regulations (Cross-State Air Pollution Rule, Cement MACT, Mercury MACT, etc.) and tightened several exiting ones (NESHAPs, NAAQs, etc). With the new standards, and revisions to existing ones, many formerly compliant facilities may not find themselves no longer able to meet their existing air permits. In addition, some facilities will need to complete the application process again for new permits based on the new standards. This process can be exceedingly difficult, due to the complexity of the regulations. Many facilities end up getting lost along the way, potentially costing them millions of dollars in the process.

A while back Baghouse.com had the opportunity to speak with Trinity Consultants, an international firm that specializes in assisting industrial companies with air quality regulatory compliance challenges, about the coming changes in the regulatory scene and how companies can avoid getting lost in the process. The following are some excerpts from that interview that we feel will be helpful for our readers.

Interview with Trinity Consultants

What would you say is the most difficult section of current clean air regulation for industry to come into compliance with?

“At present, the new National Ambient Air Quality Standards (NAAQS) and associated U.S. EPA dispersion modeling requirements for demonstrating compliance with nitrogen dioxide (NO2), sulfur dioxide (SO2), and fine particulate matter (PM2.5) are the most difficult provisions of the clean air act regulations for new or modified facilities.  U.S. EPA has also promulgated additional challenging requirements that affect specific industries or specific source types including National Emission Standards for Hazardous Air Pollutants (NESHAP), Maximum Achievable Control Technologies (MACT), and New Source Performance Standards (NSPS) for industrial-commercial-institutional steam generators (boilers), electric utility steam generating units (utilities), portland cement manufacturing, and others.”

What problems do you encounter with regards to dust collection/particulate matter (PM2.5)emissions?

“Dust collection, capture, and control is an important consideration for compliance with the PM2.5 NAAQS as well as compliance with the new NESHAP, MACT, and NSPS noted above. ”

One of the “scariest” new regulations is the Mercury MACT; what role will baghouses play in meeting these new standards?

“Most technologies for collecting mercury emissions involve the use of a baghouse. The most common include injecting a material to absorb the mercury in the airstream, usually activated carbon or a proprietary sorbent compound, which then needs to be collected from the airstream just like any other particulate matter would be, by the baghouse. In some cases the only way to handle this increased particulate load is to upgrade the baghouse. This could mean replacing the bags with more efficient PTFE membrane bags, expanding the baghouse (either by added more compartments, using a larger baghouse, or by switching to pleated baghouse filter elements).”

What problems do you encounter frequently with the regulatory process that are the most frustrating?

“We have clients that have had to cancel proposed capital expansion projects due to the economic and/or operational infeasibility of complying with the new NAAQS provisions for PM2.5, SO2, & NO2.”

What can companies do when they feel overwhelmed by the often complex permitting process to make sense of the situation?

“Our clients frequently request staff from Trinity Consultants to train, advise, or develop strategic guidance for their environmental, management, operations, and/or legal staff on the complex environmental topics or have Trinity Consultants directly assist with their permitting and compliance needs.”

What do you feel is the most important thing for companies to keep in mind with regards to compliance issues?

“Stay up to date (fresh, timely) on the regulatory rule changes affecting their industry.  Participate in industry associations or work groups that focus on environmental requirements for your industry.  Companies can also find timely updates, regulatory notices, and training courses at www.trinityconsultants.com.  We also suggest that companies subscribe to Trinity Consultants’ periodic publications which include Environmental Quarterly and eNews at www.trinityconsultants.com/subscribe”

How do these previously mentioned regulations come into play with regards to dust collection? (National Emission Standards for Hazardous Air Pollutants (NESHAP), Maximum Achievable Control Technologies (MACT), and New Source Performance Standards (NSPS) for industrial-commercial-institutional steam generators (boilers), electric utility steam generating units (utilities), portland cement manufacturing, and others)

“For existing utility sources, the 0.03 lb/MMBtu limit should easily be met with a good ESP, and does not force you into a baghouse – our understanding is the crossover point may be about 0.005 lb/MMBtu filterable.  For new utility sources, the limit is very low and could only potentially be met with a baghouse. For plantas de cemento, ESPs are likely a thing of the past and existing baghouses will likely need new filter media or polishing baghouses.  There are many retrofit projects currently being pursued.  With the new NSPS, lower than 0.002 gr/dscf bags are being evaluated.  Getting suppliers to guarantee PM emissions limits on new units that meet the standards will be very challenging.  In some places, two bags may be needed in series, one for lime injection providing some scrubbing effect and then a final bag house.  Meeting the PM limit is very challenging for the cement industry, requiring periodic maintenance program improvements, even a single bag leak can take you out of compliance. Industrial-commercial-institutional boiler considerations:   
For solid fuel-fired boilers, it appears that fabric filters will be required (whenever the rule becomes effective).  At this time, it’s impossible to tell what the reconsideration will do as many companies are looking to expand it. 
For liquid fuel-fired boilers, fabric filter may be an option.  We expect companies that installed a new baghouse would have used a BLDS since it appears to be preferred over a COMS.  We expect some companies will convert to natural gas instead of upgrading their solid and liquid-fired emissions controls.”

What specific problems do you find that companies have gaining compliance with regards to their baghouse?

“Opacity limits with short-averaging periods are a big problem for ESPs – almost any ESP on a solid fuel unit cannot run 100% compliance, though 99%+ is possible.  A baghouse can run essentially 100% compliance.  Since they all have COMS you record every hour.  PM CEMS are a big problem as their accuracy is suspect – back-to-back testing with Method 5 and a PM CEMS can give very different answers.

For the cement industry, the greatest challenge in meeting the new PM limits, other than the limits being low, is the related requirement to meet the limits with a PM CEM.  There is virtually no data of this type in the industry and the monitoring equipment is complex.  Therefore, there is significant uncertainty at to whether the limit is achievable, day in, day out. 

According to the Council of Industrial Boiler Owners (CIBO) the level of emission reduction for industrial-commercial-institutional boilers has not been demonstrated to be achievable by industrial applications, and may only be achievable on a consistent basis with the use of new technology not commonly used in industrial applications.  Electrostatic precipitator suppliers and bag house suppliers both indicate that this new standard is not achievable with the exception that the type of exotic filters used for clean rooms in food production and some pharmaceuticals may be applicable but at exorbitant cost.”

What aspect (or specific regulation or set of regulations) do you feel needs to be revised or reformed the most to make the regulatory process more conducive to industrial growth, while still providing protection for our environment?

“I believe EPA and state agencies need to revise or reform their dispersion modeling methodologies and/or tools to more realistically assess compliance with the new 1-hr NAAQS.”

Would you say that current regulation is hampering companies’ efforts to expand their operation?

“Yes.”

Advice for Companies

When working with a client to achieve overall compliance of their facility with applicable regulations, what advice or warnings do you give to them regarding the proper operation, and maintenance of their baghouse system?

“Periodic baghouse maintenance programs for many plants will need to be improved. There is a lot facility operators can do to make their baghouses run more efficiently.”

How important is it for plants to make sure their dust collection system is functioning properly?

“It will be very important to demonstrate continuous compliance with the more stringent regulatory requirements.”

Do you believe that it is in a facilities best interest to upgrade outdated and undersized dust collection equipment? In your experience (expert opinion) do you feel that it is worth the investment in capital for the potential benefits?

“Upgrade decisions will be required on a facility by facility basis but in many instances, upgrading of equipment will be necessary / required.”

What percentage of your clients would you say are having problems with their baghouse system that are causing them to be out of compliance with clean air regulations?

“By and large, our clients are in compliance with clean air regulations (continuous compliance is not an option for business risk mitigation).  However, the recent stringent regulations presents significant challenges and our clients are actively pursuing and developing solutions to implement in the next year or two.”

About Trinity Consultants: Founded in 1974, Trinity Consultants is an international firm that specializes in assisting industrial companies with air quality regulatory compliance challenges.  Trinity also provides professional training, environmental modeling software, EH&S information management solutions, and EH&S staffing services.  Environmental professionals can subscribe to Trinity’s free Environmental Quarterly publication at trinityconsultants.com/subscribe.

| Dominick DalSanto is an Author & Environmental Technologies Expert, specializing in Dust Collection Systems. With nearly a decade of hands-on working experience in the industry, Dominick’s knowledge of the industry goes beyond a mere classroom education. He is currently serving as Marketing Director at Baghouse.com. His articles have been published not only on Baghouse.com , but also on other industry related blogs and sites. In his spare time, Dominick writes about travel and life abroad for various travel sites and blogs.

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Dust Collector Fire and Explosion Highlights Need for Combustible Dust Considerations In System Designs

New-England-Wood-Pellet-combustible-dust-fire-explosion

A massive fire and explosion in the dust collection system of a New Hampshire wood pellet manufacturer demonstrates the need for adequate system design to prevent combustible dust explosions in general industry.

By Dominick DalSanto
Baghouse Technology Expert and Sales Director
Baghouse.com

May 16 2012 – Baghouse.com Editorial | On October 20 2011, a combustible dust fire began in the wood pellet cooler, most likely caused by a spark or ember from the pellet hammer mill. The fire then spread through the ductwork throughout the plant, eventually reaching the dust collector causing it to explode. When the collector exploded, the explosion vented through the baghouse’s explosion vents into adjacent storage silos setting them ablaze further spread the fire throughout the plant. More than 100 firefighters and emergency personnel from at least 14 towns worked for over 15 hours to put out the blaze.

The OSHA report outlines specific areas where the plant lacked adequate spark detection devices, fire suppression systems, and explosion venting/protection within the dust collection system. The fact that the plant had been cited by OSHA for several of the same issues previously after a 2008 incident, led to OSHA assessing total fines of $147,000.

Examining what went wrong in this incident highlights the need for diligence on the part of plant management and operators regarding the dangers of combustible dust.

What Went Wrong?

The October 20 2011 fire and explosion at the Jaffrey, NH plant was not the first combustible dust related incident at the plant. In 2008 the plant experienced a similar fire and explosion that caused more destruction than the most recent one. After completing its investigation, OSHA at that time fined the plant over $100,000 for safety violations that led to the fire. Subsequently, the plant, in an attempt to prevent another such occurrence, “retained engineers and consultants, and spent over $2 million on various improvements to enhance worker safety at its Jaffrey facility” according to a release from the company. This apparently including the installation of some explosion isolation devices in the ductwork (Rembe explosion isolation device) and installed explosion protection (explosion vents) on the baghouse. However the company’s effort and expense failed to prevent another incident from occurring.

Fire fighters work to put out a massive blaze caused by a destructive combustible dust fire and explosion at the New England Wood Pellet Company's Jaffrey, NH facility.

Fire fighters work to put out a massive blaze caused by a destructive combustible dust fire and explosion at the New England Wood Pellet Company’s Jaffrey, NH facility.

The OSHA report is quite thorough in its description each poorly designed, installed and operated part of the dust collection system either caused or intensified fire and subsequent explosion.

For example the report cites the plant for 2 main offenses. The first one is regarding poor housekeeping throughout the plant that led to large accumulations of combustible wood pellet dust forming on top of machinery (such as the pellet cooler where the fire began) and on elevated surfaces such as overhead rafters, ceiling joists, troughs, etc. Secondly, and more seriously, the plant was cited under the General Duty Clause of the OSHA Charter* for failing to take reasonable steps to prevent a combustible dust fire/explosion from occurring. OSHA cited several industry standards such as the National Fire Protection Association building code that the plant failed to heed in the design and construction of the plant’s dust collection system.

Ductwork Lacked Sufficient Spark Detection, Fire Suppression, or Explosion Isolation Devices

A major oversight in the ductwork system, was the lack of appropriate spark detection, fire suppression or fire isolation devices on all of the ductwork between the various machines throughout the plant. For instance, OSHA reported that the connecting ductwork between the pellet hammer mills, the pellet cooler, the bucket elevators storage silos and most of the dust collectors in the plant had no spark detection system, fire suppression system, or explosion isolation devices installed. The only control device the plant had was an explosion isolation device on the conveying duct between the pellet cooler and the pellet cooler baghouse. However, the device did not function properly and allowed the fire to propagate further downstream into the baghouse.

NFPA 664 (2012) Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities: 8.2.1. and Hazard Determination 8.2.4.1. – Conveying systems with fire hazards should be isolated to prevent propagation of fire both upstream and downstream (OSHA isolation can mean spark detection and suppression). 5.2.5.1 Prevention of Fire Extension: When limitation of fire spread is to be achieved the following criteria shall be demonstrated…(4) Particulate processing systems (dust collection systems) shall be designed, constructed, equipped and maintained to prevent fire or deflagration from propagating from one process system to an adjacent process system.

Additionally, the ductwork was not engineered and/or constructed to sufficient strength to withstand the maximum anticipatable explosive pressure resulting from a conflagration involving its intended payload (combustible wood dust). This led to the duct bursting open, releasing the explosion into the plant near firefighters and may have been a contributing factor in the fire by-passing the isolation device.

NFPA 664 (2012) 8.2.2.2.3, Sets forth alternative safety criteria for ducts with a deflagration hazard, to ensure that the ducts are builds with a sufficient strength and with appropriately sized/located protection devices to handle the maximum expected pressure generated by a dust explosion. 

Baghouse Was Not Adequately Protected Against Explosion Hazards

The plant recently installed explosion vents on the baghouse explosion vents.* However, the design and installation of the explosion protection on this particular baghouse may actually made things worse than if there had been none at all.

When the fire reached the baghouse and caused the finely dispersed dust to ignite, the resulting pressure and fireball should have been vented outside the building. However, the explosion vents on the baghouse faced the direction of adjacent storage silos (containing wood dust). When the explosion was vented out it ignited the storage silos resulting in a major portion of the fire.

Additionally, OSHA’s investigation showed that the baghouse lacked an explosion suppression system, was not designed and/or constructed to withstand the maximum unvented pressure of a combustible dust explosion, and in the absence of proper explosion protection, was located indoors.

As a result of these failures, when the reached the dust collector, the resulting explosion: blew the dust collector’s door off its hinges, creating a missile hazard, blew backwards into the duct, which burst open, and blew out the dust collector’s exhaust muffler and roof stack, causing the pressure/deflagration to be vented inside the building near responding firefighters.

NFPA 664 (2012) 8.2.2.5.1.4. Requires an outdoor location for the dust collectors with fire or deflagration hazards, unless they are equipped with one of the following: (4) listed deflagration suppression system, (5) deflagration relief vents with relief pipes extending to safe areas outside the building and the collector meets the strength requirement of this standard (i.e. built with sufficient strength to withstand the maximum expected explosions pressure). NFPA 664 (2012) 8.2.2.5.3 requires dust collectors with deflagration hazards be equipped with an appropriate-sized explosion suppression system and/or explosion relief venting system designed per NFPA 68 (Explosion Protection by Deflagration Venting) and NFPA 69 (Explosion Prevention Systems), and also that such dust collectors be built to design strength that exceeds the maximum expected explosion pressure of the material being collected. NFPA 69, 12.1.2 requires “Piping, ducts, and enclosures protected by an isolation system shall be designed to withstand estimated pressures as provided by the isolation system manufacturer”. NFPA 69, 12.2.2.3 “System Verification” requires that systems shall be verified by appropriate testing under deflagration conditions to demonstrate performance.”

These design oversights directly increased the destructive power of what had until then been only a dust fire in the ductwork.

Lessons Learned From Wood Pellet Company Dust Explosion

Simply put, this disaster was bound to happen due to glaring design and/or construction flaws throughout the entire system.

The fact that multiple similar incidents have occurred at the facility demonstrates that the dust collection system, and perhaps even the entire production process requires modification to ensure this kind of incident does not occur again.

Under OSHA’s National Combustible Dust Emphasis Program, OSHA inspectors are on heightened alert for any combustible dust hazards in facilities in all industries. Indeed OSHA is under a federal mandate and its has as its own goal to issue a comprehensive combustible dust standard for general industry. In the meantime, OSHA has been citing plants under the general duty clause for having combustible dust hazards. In most cases, OSHA is informally requiring general industry to conform to the NFPA’s guidelines for combustible dust hazards. As seen in this case following they suggestions would have prevented this kind of incident from occurring.

Therefore, we can take away from this the need to be conscientious and proactive regarding combustible dust hazards in your facility. As we have seen, being reactive will simply not do.

Footnotes:

* OSHA General Duty Clause (a) Each employer — (1) shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees; (2) shall comply with occupational safety and health standards promulgated under this Act.

*  Baghouse Explosion Vents – Explosion vents are a form of explosion protection used on baghouses. During normal operation the vents are closed and maintain an air-tight seal. However, if an explosion occurs within the baghouse, the vents are designed to “strategically fail” being the weakest part of the baghouse structure, thus allowing the pressure from the explosion to vent out and away from other combustible materials and workers.

| Dominick DalSanto is an Author & Environmental Technologies Expert, specializing in dust collection systems. With nearly a decade of hands-on working experience in the industry, Dominick’s knowledge of the industry goes beyond a mere classroom education. He is currently serving as Sales Director at Baghouse.com. His articles have been published not only on Baghouse.com , but also on other industry related blogs and sites. In his spare time, Dominick writes about travel and life abroad for various travel sites and blogs.

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