Filtration Considerations for CPI Facilities

June 1, 2023 | By Ulrich Latz and Wim Callaert

Numerous factors are taken into account when designing a filtration system, including technical, logistical and safety considerations

Filtration is an essential step in the production and processing of many materials in the chemical process industries (CPI). Beyond the efficacy of the filtration solution itself, there are other complexities that chemical engineering facility operators should understand (Figure 1). This article looks at some of the lesser-known factors that make proper filtration in chemical manufacturing and processing applications a multifaceted challenge, but one that can be solved with the right filtration technologies.

FIGURE 1. Proper design and maintenance of filtration systems in chemical manufacturing and processing operations are critical. So too are the use of quality products, attention to operator safety and knowing when to lean on experts for assistance

Each chemical process presents unique considerations for filtration, where the presence of contaminants can interfere with sensitive reactions, leading to decreased quality of the desired output product. Particulate-matter removal for feedstocks and ancillary fluid circulation are vital, because impurities can also corrode and damage the internal surfaces of process equipment, leading to costly maintenance.

Imputities severely threaten operational performance in interconnected chemical processes, as inefficiencies in one area can quickly propagate to others. Installing appropriate filtration solutions at key process points helps to reduce these risks and curb expenses while improving end-product quality.

Whether by purifying feedstocks, filtering process fluids for reuse or for final purification, chemical facilities rely on many types of filtration systems to accomplish the desired separation. While the design and operation of these systems can vary greatly, there are common considerations for all filtration systems that are important to understand, as discussed in following sections.

Although filtration systems all strive to achieve the same goal, quality materials are integral for ensuring the best results (Figure 2).

FIGURE 2. Industrial filters must be made from materials that meet the stringent safety, sanitation and quality requirements for industries like paints and coatings, and specialty chemicals

Filters are typically made from various plastics, polymers and fibers containing different additives and surfactants. For the automotive paints-and-coatings sector especially, filtration products must be silicone free, including materials of construction and the full production process. "Silicone free" can mean different things to different users; however, regardless of whether it is a filter bag or filter cartridge, the product must not contain silicone or various other crater-forming substances. In sufficient volumes these impurities can cause finishes to "crater away" from the contaminant, or they may cause paints and coatings to lose adhesion.

The potential diffusion of leachable substances into chemical processes is why it is critical to ensure that the filter media are free of impurities. Facility operators should seek an assurance from their suppliers, who can, in turn, offer complete traceability into the filtration products, including lot numbers and supplier sources. Furthermore, all products should exhibit a globally consistent quality, where product designs and materials do not waver in terms of performance, safety or dependability — regardless of where they are made.

Filters with oil-adsorption capabilities can further offer a solution to paint manufacturers that must ensure batches remain fit for end-customer use. Pure non-lubricated plastics, such as polypropylene, feature oleophilic and hydrophobic characteristics that attract oils to their surface while repelling water particles. These filters are commonly used in paint baths within the automotive industry, either as a remedy or preventive measure.

In many CPI facilities, system operators must wear protective gear, including masks, to change out dirty consumable filter media, such as filter bags and filter cartridges. Limiting maintenance intervals at these points to the bare minimum is important, since volatile organic compounds (VOCs) can be released when opening filtration units to change consumables. VOCs can be either naturally occurring or synthesized, but tend to have high relative vapor pressures, meaning they easily evaporate when exposed to air.

Maintenance needs will largely depend on the type and capacity of the selected filtration equipment. Filtration systems must be designed and adequately sized to operate for long intervals between changeouts. Often the goal is to go weeks or even months between changeouts of consumable filter media. This helps to limit the risk of introducing industrial solvents into the production environment each time a unit must be serviced.

Facility operators are advised to consult an industrial filtration expert about options for large-capacity systems or, in other cases, automatic self-cleaning systems (Figure 3) that greatly reduce the need for manual intervention. The market offers many configurations and features that can extend the time between consumable filter changeouts — an expert can help you strike the right balance between frequency and dollars spent.

FIGURE 3. Automatic mechanically cleaned filters, like this commercial system, can provide continuous flow, simplified maintenance and worry-free operation because there is less risk of harmful VOCs being released in the production environment

Also, housings for filtration units — as long as they are pressure vessels — must be properly certified. The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) and the Pressure Equipment Directive (PED) are two major standards that ensure the safe operation of pressure equipment worldwide. The ASME BPVC was established as a set of procedures for the design, manufacture and use of boilers, pressure vessels and piping, and is used in the U.S. and Canada as well as in many other countries. PED is an E.U.-based regulation that imposes similar safety and design requirements for pressure equipment.

These regulations further define design and safety parameters for filtration systems, fluids in use and system operating and ambient conditions. In all cases, it is important to ensure a filtration solution carries the required stamps and approvals by third parties, denoting the equipment has been built to the highest level of safety and has undergone assessment. At times, required certifications may further demand CE marking in accordance with PED based on the EN 13445 or AD 2000 pressure vessel codes.

Many factors affect the efficiency and effectiveness of filtration processes in chemical manufacturing and processing applications. These include the size of the particles to be filtered, filter media pore size, fluid viscosity, system temperature and pressure, and the concentration of the suspension. To ensure optimal performance, industrial filtration systems must be designed to account for these requirements.

For instance, a filtration system can be too efficient — and costly — if desired substances are filtered out along with impurities. Particle sizes can range from as small as 0.1µm (for example, bacteria) to as large as 2,000µm (for example, sand grains).

End users must first assess which parts of the containment are undesired and which can be permitted. This is critical in choosing the best and most economical filter type, grade and size. If the filter media pore size is too small, for instance, premature clogging may occur, and if the pores are too large, impurities may pass directly through the filter.

The amount of contaminant will also play an important role in the sizing of the equipment. In some cases, a simple consumable filter with a nominal media configuration can perform effectively, and at other times, one or more multi-bag housing configurations having high-capacity media may be required. The market offers a vast line of products so that end users can find an optimal fit for each application.

Very high contamination loads may also influence end users’ choice toward an automatic filtration system (Figure 3). These systems function without consumable or disposable media and are based on a backflush or mechanically cleaned design that keeps them operating continuously without stopping to change the filter medium. Other factors include the following:

Viscosity. Of further note is that the viscosity of a fluid affects the pressure drop across a filtration system. The greater the viscosity, the higher the pressure drop, due to the increased resistance to flow. In turn, the amount of time it takes to complete the filtration is increased. This pressure drop must be factored in when designing a system as higher-viscosity fluids can place high levels of stress on the filter, possibly damaging it.

Temperature. Low operating temperatures meanwhile can slow down the flowrate, requiring a more powerful pump and more robust filtration materials to handle the increased pressure from within the system. At high temperatures, things can get even more complicated. Excess heat may require additional cooling elements to keep the fluid within safe operating temperatures, as well as to avoid frictional losses.

Pressure. Likewise, where operating pressures are too low, the flowrate of the fluid will decrease, and the filtration system may not be able to effectively remove impurities. Conversely, if the pressure is too high, then the fluid's velocity will increase significantly, leading to a process that is too fast and can damage system components. For these reasons, some filtration systems are designed with regulators to adjust pressures to desired levels.

Environmental impact. One important trend linked to industrial filtration processes is reducing environmental impact and cost risk by minimizing chemical and water waste generation. Properly engineered filtration systems can play a key role in assuring that wherever disposable filters need to be used, the filter is sized optimally to fit the batch size, or, in other cases, that automated filters generate minimal backwash volume and/or purged waste concentrate.

While these are routine challenges, it is impossible to predict all the complexities that can impact chemical manufacturing and processing operations. For this reason, companies are advised to consult with specialists who have solved the same challenges many times before and can troubleshoot problems, anticipate facility needs and advise a correct solution from the start.

Additional best practices for industrial filtration can be broadly applied to all CPI facility challenges and include the following:

Considerations for quality in, quality out. Filtration should take place before and after a chemical manufacturing process has been completed, requiring filters at liquid entry and exit points (for instance, at loading stations before liquids are transferred to tankers and again as trucks unload). Any time chemicals are transferred, filtration should be employed on each end to guarantee the quality of the product (Figure 4).

FIGURE 4. Consider an industrial filtration system wherever there is possibility for contamination on process lines. Upstream filtration can help to minimize operational costs by protecting more expensive downstream filters

Furthermore, filtration systems should be in strict compliance with industry codes and standards. This ensures that the system is working properly and will pose little risk when it is installed and with minimal disruption to the environment (thus also helping to reduce the risk of contamination; Figure 4). It should also be configured in such a way that future maintenance can be carried out easily.

Considerations for operator safety. For liquid filtration systems, such as bag and cartridge filter housings, that need to be opened and closed for consumable replacement, operator safety and ergonomics need to be factored in. The height at which a filter housing needs to be opened and where the consumable needs to be extracted from is a typical example. For instance, where filter housings are normally positioned in a vertical setup, an inclined or even horizontal position may dramatically reduce the working height.

The method of opening and closing the filter unit can make a difference as well. Where traditional units are often equipped with multiple bolts, more operator-friendly, quick-opening-and-closing systems can be chosen to access consumables in seconds as opposed to minutes of difficult manual labor (Figure 5). Note that units should be equipped with a proper safety system that blocks the quick-opening mechanism while the housing is under pressure.

FIGURE 5. In CPI plants, operators need bag filtration solutions that are simple and safe to use like this multi-bag filter housing that features quick opening and locking mechanism. Standing in place, the operator can rotate the hand wheel and open the cover. There is no requirement to have full movement and access around the housing or use any tools as with conventional bolted closures

High-capacity filters, offering extra filtration surface in the same filter housing, can also minimize needed maintenance cycles and as such, reduce operator exposure to potential hazardous environments.

Finally, ample space must be provided for operators and maintenance personnel to access and maneuver around the filtration unit in such a way that minimizes exposure to other safety hazards within the environment.

In terms of revenue, the global industrial filtration market was estimated to be worth $33.5 billion in 2022 and is poised to reach $45.2 billion by 2027, growing at a compound annual growth rate (CAGR) of 6.2% [1]. The market is presently driven by a host of factors like those discussed here, including government enacted environmental regulations, more stringent requirements for safe environments and the increasing need for process reliability. These factors are driving demand for high-integrity, high-performing filtration solutions.

Great care must be taken when implementing filtration systems in CPI facilities. Engaging an expert to design the filtration system is a wise investment. An expert designer will be knowledgeable about the technical aspects of the filtration solution, can customize the setup to the facility's specific requirements and can minimize the risks associated with inadequate filtration measures. They will also be up to date on the latest industry standards and technologies and can suggest the most effective approaches. Additionally, they will ensure that the design falls within all industry requirements and safety guidelines.

Designing, implementing and maintaining filtration solutions for chemical manufacturing and processing applications are rarely straightforward processes. Companies seeking to optimize their outputs will benefit from high-quality filtration products and the assistance of industrial filtration experts who know everything there is to consider.

Edited by Gerald Ondrey

1. MarketsAndMarkets Pvt., Ltd., "Industrial Filtration Market – Global Forecast to 2027," Report Code EP 4471, March 2022, www.marketsandmarkets.com, accessed 3.22.23.

Ulrich Latz is global product manager at Eaton's Filtration Division, based in Germany. He has more than 10 years of industrial filtration-related experience. Latz holds a master's degree in engineering from the Cologne University of Applied Sciences.

Wim Callaert is senior product manager at Eaton's Filtration Division, based in Belgium. He has 30 years of filtration-related experience in global product management, sales and marketing. Callaert holds a master's degree in engineering from the IHR in Brussels.