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.
Is there a magic solution?
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.
Meeting the new standards
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.
Why do emissions occur?
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.
Can dust penetration occur at the needle holes on filter bag seams?
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.
Why the discrepancy?
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:
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.
This article was contributed by the Filtration technology team.Related content:
16 May 2019
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.
Improving Sterilising Filtration in the
June 4th, 2019 | 3PM London / 10AM New YorkRegister Now The filter vendor’s responsibilities
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.
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.
15 May 2019
This blog was contributed by Phil Green, application and training manager, Parker Gas Separation and Filtration Division, EMEA.
10 May 2019
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.
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 BHAPulsePleat 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 BHAPulsePleat 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 BHAPulsePleat technology.
By employing the 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:
This article was contributed by the Filtration technology team.
1 May 2019
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:
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
11 Apr 2019
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:
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:
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:
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:
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:
The foundry engineering team determined that installing Parker BHA PFEs in the dust collector was the most cost-effective solution.
Post installation results include:
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.
This blog was contributed by the Filtration technology team, Parker Industrial Gas Filtration and Generation Division.
13 Mar 2019