Filtration

The increased value being placed on responsible corporate citizenship and green initiatives has prompted cement manufacturing companies to look closely at how they will comply with the proposed National Emission Standards for Hazardous Air Pollutants (NESHAP) Particulate Matter (PM) limits. The effect of these potential new limits in the United States has had a ripple effect on the design, production and adoption of filtration technologies and best practices around the world.

This blog examines solutions to baghouse particulate removal efficiency to meet the proposed NESHAP PM limits and presents the results of two studies conducted on the effects of taped seams vs. standard felled seam construction on emissions reduction.

For complete study details including data and methodology, download the full white paper.

Even before the details of these new regulations were settled, many cement manufacturers were already in search of a special solution — a magic filter bag that would make even the most stringent emissions challenges a thing of the past. As much as a singular solution that meets this need is desired, no such option exists.  

A filter bag is only one of the many components in a dust collector. The key to effective particulate removal efficiency depends on the successful operation of all parts of the system.

These companies must consider a host of components, operating conditions and other variables such as age and maintenance history in order to ensure their dust collection system will offer optimum performance and meet the emissions levels defined in the NESHAP. 

It is well known that polytetrafluoroethylene (ePTFE) filters are exceptionally efficient in capturing particulate on the collection surface of a filter bag without having to rely on a dust-cake or control layer. A properly designed and maintained dust collector installed with these filters can meet the emissions levels required by the new NESHAP rule. 

Meeting the limits is achievable, but the question that continues to elude companies is: For how long? There is a lack of historical data available for continuous outlet emissions that shows the point in a filter’s life when emissions begin increasing.

Design, operation, age and process conditions are the variables that contribute to filter life. Where these can present dynamic conditions individually, their combination makes for an endlessly complex matrix of possibilities. To this end, the performance of a system with the same specifications can operate differently in every environment in which it is applied. 
 
In order to mitigate these dynamics, companies are choosing to segment the challenges they face in order to contain the variables.  

For example, understanding that increased emissions will result as ePTFE membranes age and develop fractures and fissures along flex lines, gives the plant operations managers and engineers something to evaluate and preempt through scheduled maintenance. 

One hypothesis based on a previously published study, suggests that dust penetration/leakage can occur through the stitching on filter bag seams and taping them can have a positive impact on the reduction of particulate emissions.

Separate testing, commissioned by Parker Hannifin, that adhered to the US EPA’s Environmental Testing Verification (ETV) testing protocol yielded different results.

The independent testing commissioned by Parker put the filtration through the rigors that more closely resemble normal baghouse operation, in a laboratory setting. This testing offers a more accurate portrayal of durable filter life than the previously published study that only simulated the early seasoning phase. ETV protocol does not draw conclusions from results taken during the seasoning phase.

ETS, Inc, an independent laboratory, was commissioned by Parker to perform the testing. The tests were performed per the US EPA’s ETV program and in accordance with the ASTM Test Method D830-02 utilizing Parker 22 oz. woven fiberglass media with ePTFE membrane. The results showed:

• Tape sealing of the seams offers no significant additional benefit for reduction or prevention of emissions through filter bags.
• In actual application, seams that have been taped could actually reduce the total filtration area of the bag. 
• Taped seams do not offer any significant additional benefits compared to stitched seams.
• Standard felled seam construction on filter bags is not a source of increased particulate matter emissions.

The truth is that there is no magic filter bag to be discovered, but there are practical lessons to be learned: Particulate removal efficiency is a function of the effective operation of all parts of the system. Properly installed and maintained ePTFE membrane filters are an effective solution for meeting the NESHAP emission limits.

Download the full white paper, "In Search of the Magic Filter Bag", for complete study details including data and methodology.

This article was contributed by the Filtration technology team.

Reducing Dust Collector Maintenance and Energy Costs in the Cement Industry | Case Study

BHA® Pleated Filter Elements Improve Dust Collection for the Foundry Industry

Foundry Eliminates Shutdowns and Extends Baghouse Filter Life

Filter qualification typically involves demonstrating bacterial retention of a filter under process simulated conditions.

A crucial first step in this is in the hands of the filter vendor, who is responsible for producing a ‘fit for purpose’ filter such as those in Parker's PROPOR membrane filter range. Supporting data which demonstrates filter performance under standardized test conditions should then be presented in a validation guide.  

June 4th, 2019 | 3PM London / 10AM New York

• The material of construction needs to be consistent and defined. There is no point in validating a filter if the material is not consistent across all products. 
   
• The performance limits of the filter – encompassing temperature, chemical compatibility, pressure and bacterial retention – should be defined and published in the validation guide.
   
• The validation guide must explain how to correctly sterilize the filter by steam or irradiation.
   
• The filter vendor must provide proof that when operated within the published performance limits, the process will not alter the filter performance. Among the elements the vendor needs to consider are:

• Will differences in temperature alter the filter’s pore size and shape so potentially making it easier for bacteria to pass and therefore affect microbial retention?
   
• Could the presence of certain solvents affect microbial retention by altering the pore size or shape?
   
• How will the filter deal with adjutants? These are notoriously difficult to filter sterilize because they somehow change the filter membrane’s properties making it easier for bacteria to pass through. Although it had never been proved, there is a theory that adjutants lower the surface tension of a membrane by acting as a surfactant. In effect, this lubricates the membrane.
   
• If the process is run at a high differential pressure will this affect microbial retention? Put simply, if you push hard enough something may get through, or the filter build will fail.

A destructive test – bacterial retention performed during validation – should be carried out and this is typically undertaken by the filter manufacturer.

In addition, a non-destructive filter integrity test should be performed by both the end user and the manufacturer. This will be in the form of either a bubble point test or a diffusion test and will link to the work carried out in the destructive test.

Process qualification must be carried out to prove the filter works in the customer process and with the fluid stream.

You can access guidance on process qualification in PDA Technical Report 26 and in ISO 13408-2:2018.

To carry out effective process qualification, it is best to start at a small scale, develop the process and then test it. Testing should then be carried out at the largest scale possible – so with the largest batch size, at the highest pressure and across the longest process time. If the feed stream is variable, then this should be taken into account. However, typically at this stage the feed stream is fairly well defined: the volume may change but the constituents of the feed stream will be the same.

In order to carry out effective filter qualification, you need to show that the combination of a defined, consistent filter membrane, used to filter a particular and controlled feed stream, under defined conditions of temperature, time and pressure, will retain bacteria.

To learn more about filtration in the biopharmaceutical industry, sign up for our webinar

Learn more about Parker's PROPOR range of biopharmaceutical membrane filters

This post was contributed by Paul Hymus, product manager (filtration), Parker Bioscience Filtration, United Kingdom

Parker Bioscience Filtration specializes in automating and controlling single-use bioprocesses. By integrating sensory and automation technology into a process, a manufacturer can control the fluid more effectively ensuring the quality of the final product. Visit www.parker.com/bioscience to find out more.

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When it comes to supplying dry, inert nitrogen for manufacturing applications, there’s a lot more to PSA technology (pressure swing adsorption) nitrogen generators than vessels filled with CMS (carbon molecular sieve).

• Gas supply interruption prevention.
• Full compliance with gas purity requirements.
• Over-flow prevention.
• Economy control and energy-saving EST technology. 
• Snowstorm filling.

• Fitted integrally at the point of nitrogen gas discharge from the NITROSource generator, it ensures the flow of gas to the application is constant, regardless of system pressure.
• Unlike a needle type valve that can restrict flow under fluctuating pressure, the mass flow controller delivers a consistent nitrogen flow regardless of what is happening with pressure down-stream.

• The correct quality gas is delivered to the application or process.
• Visual confirmation of the gas quality.
• Option to data log with 4-20mAmp outputs.

In the unlikely event of the nitrogen gas not meeting the specification requirements, the outlet to the application is shut off and the off-specification gas is vented to atmosphere at approximately 2/3rds of the generator flow capacity. The nitrogen generator automatically corrects the situation without the need for intervention. The customer is assured full compliance with specified gas purity being met under all circumstances, no product recalls or spoilage, as well as labour, time and cost savings that would be required for manual intervention. The image to the left shows an outlet valve block with off-gas by-pass valve at the front.

The NITROSource nitrogen gas generator incorporates two energy-saving features:

This procedure ensures that the CMS is filled in the columns at maximum packing density. Advantages include:

• The CMS cannot move and turn to powder through attrition.
• There are no leakage paths to affect purity.
• There are no leakage paths to prevent complete regeneration.
• Less CMS is required to produce a given volume of gas.
• No topping up or replacement of CMS is required.
• The CMS is filled for the life of the generator and is not a consumable item.

This blog was contributed by Phil Green, application and training manager, Parker Gas Separation and Filtration Division, EMEA.

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Foundries rely on the uninterrupted operation of their dust collection systems to assure a safe and productive work environment and proper operation of equipment. When dust collection systems present maintenance issues, foundries can realize tens of thousands of dollars in inefficiencies. If the issues are unrecognized or ignored, the costs will multiply very quickly and can result in lengthy shutdowns.

This was the scenario that a large Midwestern foundry sought to avoid after enduring multiple shutdowns in a year’s time to perform filter maintenance on their Carborundum baghouse.  

To learn more details about this application and industrial filtration systems for foundries, download the full case study.

The foundry was having significant problems with their filters being blinded by the fine particles in the gas stream. They were operating a pulse jet baghouse with seven compartments, at 250,000 ACFM. The filters that they had in operation used conventional polyester felt technology. The system had been designed at a 4.1/1 air-to-cloth ratio.

The fine particles in the dust stream were of a volume that simply overcame the filter media. This pushed the differential pressure across the baghouse to over 8 inches. The system was rendered unrecoverable and inoperable.  

Maintenance was conducted using the same filtration technology, and the blinding effect repeated itself. The filters were only able to stay in operation for six months before the end of their useful life. As a result, the filters and labor cost the foundry in excess of two hundred thousand dollars over a year’s time. 

In the search for a solution, the foundry turned to Parker Hannifin. Parker recommended implementing spun-bound polyester BHA® PulsePleat® filter elements (PFE) in place of the polyester felt bag and cage design that had been in use. These filter elements feature a combination of pleated high-efficiency filtration media and an inner support core that forms a one-piece element that fits directly into an existing baghouse tubesheet. The BHA®PulsePleat® filter media would offer a much better air-to-cloth ratio of 2.1/1. In addition, the pleated design of the media would not be as susceptible to the blinding effect caused by the fine particles in the gas stream.  

The foundry implemented the PFEs in two phases, addressing the most problematic compartments first. After seeing positive results, it moved forward and converted the rest of the collector to pleated filters. The return on the total conversion expense of $285K was realized after sixteen months of efficient operation with no maintenance required.

After twenty-one months of operation, the differential pressure was operating in the 3-5 inch range. The filters had proved capable of handling the fine particle load without blinding. Even after a weeklong accidental shutdown of the cleaning system, the filters were able to have the particle loading and maintain a low differential and efficient operation. At this point, the foundry had realized a filter life three times greater with the pleated filtration in comparison to the polyester felt. 

Under the current operating conditions, the foundry is not planning to perform filter replacement maintenance for another twelve months. In this case, they will have seen a five times improvement in filter life by employing the BHA®PulsePleat® technology.

By employing the BHA®PulsePleat® technology, this foundry eliminated frequent unplanned shutdowns, increased ROI and extended the life of the filters in its pulse jet baghouse.  

To learn more about BHA dust collection products, watch this video:

Download the full case study to learn more details about this application and industrial filtration systems for foundries.

This article was contributed by the Filtration technology team.

Reducing Dust Collector Maintenance and Energy Costs in the Cement Industry | Case Study

BHA® Pleated Filter Elements Improve Dust Collection for the Foundry Industry

Filtration Technologies and Key Markets

In industrial manufacturing, the need for frequent, costly maintenance is often the stimulus that compels equipment operators to search for a better solution. Time is valuable, and hours spent on maintenance activities could be put towards other responsibilities. 

This was the case when a cement company searched for a solution for the short life expectancy of the filters used in its Fuller pulse jet dust collector connected to and OSEPA high-efficiency separator. 

Download the full case study, "Finding the Right Filter to Realize Savings and Avoid Costly Upgrades", to get the details on how BHA® PulsePleat® Pleated Filter Elements reduced energy and compressed air consumption costs at a cement factory.      

The company was realizing a useful life of its process dust collection filters of only two years, due to a combination of issues: Velocity of the dust in their systems was rendering the membrane material on their filter bags useless. This was allowing for bleed through to the depth of the polyester filter bag, causing an increase of operating differential pressure to over 8 inches (203mm). The high operating differential pressure led to an increase in measured emissions from the system.  

The original system was designed to handle an air flow of 61,000 cubic feet per minute. This called for 975 installed filters. Each filter was made of 16-ounce (500 grams) polyester PTFE laminated felt. The dimensions of each filter were 6.25 inches (158.75mm) by 144 inches (3,658 mm). This resulted in a total filtration area of 19,134 square feet (1,779 square meters.) The air to media ratio was 3.1:1.

The search ended when the company replaced the existing conventional bags and cages with Parker OSEPA BHA® PulsePleat® filter elements (PFE). PFEs offered the opportunity to increase total filtration area while reducing the physical space required. The same number of elements were installed but they were reduced in length from 144 inches to 57 inches. The spun-bound polyester media, set in a pleat, with molded urethane end-caps required no tube sheet or collector modifications. Due to the pleat design, the total filtration area was increased by 75 percent to 33,590 cubic feet. This reduced the air to media ratio to 1.8:1.  

After several months of operation, the cement company realized a number of savings and benefits, including:

• More than $14,000 annual savings in compressed air consumption.
• A 2 tph increase in production.
• A 55 percent reduction of differential pressure while maintaining the full flow requirement of 61,000 cfm.
• A 200 percent increase in filter bag life — equivalent to more than five years.
• The shorter element design eliminated the velocity issues and degradation of the filter media.
• The air to media ratio was reduced to 1.8:1.
• The total filtration area was increased by 75 percent.

By installing PFEs, the cement company avoided the high costs of modifying their existing equipment or adding a new dust collector. The company has realized full production capability with lower emissions, lower differential pressure, reduced energy costs and less compressed air consumption as well as longer filter life.

To learn more about BHA dust collection products, watch this video:

For more details on how Parker BHA® PulsePleat® Pleated Filter Elements reduced energy and compressed air consumption costs in this application, please download the full case study, "Finding the Right Filter to Realize Savings and Avoid Costly Upgrades".   

This blog was contributed by the Filtration Technology team, Parker Industrial Gas Filtration and Generation Division

BHA® Pleated Filter Elements Improve Dust Collection for the Foundry Industry

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Filtration Technologies and Key Markets

Business growth creates new challenges. This is the case for plant engineers and maintenance managers responsible for the efficient operation of the most common form of dust collection equipment — pulse-jet baghouses — used in foundries across the globe. Many baghouses were designed and built to accommodate a certain amount of air flow that was sufficient for past demands. As foundries have increased production, these flow requirements have amplified and the original design of the baghouses are no longer suitable. Their obsolescence is perpetuated by raised scrutiny on emissions and the focus on the business community’s responsiveness as good corporate neighbors and stewards to a sustainable environment.

In this blog, we will explore pleated filter element (PFE) technology and examine how two foundries successfully upgraded their pulse-jet dust collectors by installing PFEs, resulting in: 

• Increased air volume.
• Improved filtration efficiency.
• Reduced emissions.
• Lower overall plant maintenance requirements. 

To read about more successful upgrades in a variety of foundry application processes, and for details on PFE performance testing, download the full case study.

The Environmental Protection Agency (EPA) and Occupational Safety & Health Administration (OSHA) regulations have become increasingly more stringent, requiring foundries to upgrade their current operational ventilation systems to comply with regulatory standards. Foundries have evaluated their furnaces, shakeout, pouring and cooling lines, sand handling systems, finishing areas and many other parts of their operations reliant on pulse-jet dust collectors for proper ventilation. Their evaluations have found a multitude of problems, including:

• High air-to-cloth ratios.
• Emissions caused by poor media filtration efficiency.
• Inlet abrasion of filter bags.
• Low air volumes at source due to excessive baghouse differential pressures.
• Loss of production due to filter bag changeout downtimes.
• High upward (interstitial) velocities between filter bags, resulting in ineffective cleaning. 
• Pulse cleaning systems consume large volumes of compressed air.

As a result, foundries are looking for ways to upgrade their dust collection. The most economical and preferred option is to modify existing baghouses rather than installing completely new systems, which would require significant capital investment. PFEs provide an effective solution to this challenge.

Pleated filter elements, such as those manufactured by Parker Hannifin, are filters that use either a molded polyurethane or metal top and bottom that are used as direct replacement for standard felted filter bag and cage assemblies in pulse-jet baghouses, as well as in new equipment. Spun-bonded polyester fabric is the most common media used in PFEs because of its tight pore structure and rigid physical properties that allow it to hold a self-supported pleat —providing as much as 200 to 300% more filtration area at 99.992% efficiency than a filter bag in the same tubesheet hole.

A major Midwest foundry used a three-compartment, 882-bag shaker baghouse to ventilate four induction furnaces, a scrap preheater system, and a magnesium inoculation station. The foundry struggled with the following problems in its dust collection system:

• Twelve-month filter bag life.
• High differential pressure due to media binding caused by particulate loading.
• Loss of ventilation air in the furnace area.
• Excessive emissions.
• High labor costs associated with keeping the old system operational.

As a solution, the company converted the original shaker system to an engineered pulse-jet style cleaning system using BHA® PFEs manufactured by Parker Hannifin's Industrial Gas Filtration and Generation Division. The baghouse was retrofitted with a new tubesheet and a walk-in clean air plenum, to allow for a top-load design filter element. The baghouse has been operating consistently since the retrofit.

Since the retrofit, the baghouse has been operating consistently and the following results have been reported:

• Upgraded air volume from 28,000 CFM to the required 55,000 CFM.
• The amount of compressed air required for pulse-jet cleaning has been reduced from 60% to 40%.
• Stack testing has confirmed that performance easily meets new environmental regulations.

A large foundry that manufactures castings for the automotive industry had a top-load design pulse-jet baghouse that contained 650 felted filter bags and cages. The unit ventilated several shot blast cabinets, grinders, and other finishing equipment. The system was originally designed at an air-to-cloth ratio of 6.1:1. The filter bags measured 5.25 in. in diameter by 12 ft. in length, for a total cloth area of 16.5 ft2 per filter bag. The challenges the foundry was experiencing with the current design were:

• Bottom-bag abrasion caused by the filter bags’ bottoms hanging directly above the parting line of the hopper. Abrasive metallic dust created small pinholes in the bottom of 9 inches of the filter bags. 
• Unacceptable emissions at the discharge stack.
• Significant production time reduction.

The foundry engineering team determined that installing Parker BHA PFEs in the dust collector was the most cost-effective solution.

Post installation results include:

• Because of the PFEs' compact design, the filter bottoms were positioned five feet above the dirty-air plenum eliminating the bottom bag abrasion.
• Reduction in the air-to-cloth ratio to 3.2:1.
• Air consumption at the collector was reduced by 30% resulting in increased overall system efficiency. 
• Unplanned maintenance and shutdowns were eliminated.
• A reduction in average differential pressure across the filter elements to 3.0 to 3.5 inch water gauge.

Pulse-jet dust collectors used in most foundry applications can be successfully upgraded with the installation of pleated filter elements. The case studies show that when aggressively designed to air-to-cloth ratios and demands for increased airflow capacity cause poor dust collector performance, the installation of PFEs can dramatically lower differential pressures, improve filtering efficiencies, reduce emissions and lower overall plant maintenance requirements.

Download the full case study to read more successful upgrades in a variety of foundry application processes and for details on PFE performance testing.

This blog was contributed by the Filtration technology team, Parker Industrial Gas Filtration and Generation Division.

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