Application of Separation Techniques & Full Containment

application of separation techniques
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Process engineers devote their time to finding the appropriate application of separation techniques. There’s need for effective solid-liquid separation, cake washing, and drying steps across industries. In many chemical and pharmaceutical processes, the production operations are further complicated by the nature of the process, especially if the process is air-sensitive or toxic.  

The solid-liquid separation step may be accomplished by pressure, vacuum, or centrifugation in a batch or continuous mode. In this step, further choices need to be made regarding the type of filter media and the thickness of the cake or the cake depth during which the separation occurs. To optimize the production process, I’ve found value in thin-cake (2-25 mm) pressure separation technology for full containment, no residual heel.

Importance of Thin-Cake Filtration

Thin-cake solid-liquid separation can be defined as the formation of a cake in the 2-20 mm thickness range.  In this range, cake compressibility becomes less important in the cake building stage of a separation process.  Compressible cakes can be better handled at thinner cake depths and higher pressures. 

For example, an amorphous crystal that does not centrifuge well or requires long filtration times on Nutsche Filter-Dryers can be filtered at 45 psig with a cake thickness of 2 – 3 mm.  Thin-cakes also lend themselves to more effective washing and drying as there is less of a chance of channeling and the mechanism of “plug-flow” of liquids or gases is enhanced.

Impacting Filtration Performance

There are several parameters that can impact filtration performance:

  • Filtration pressure
  • Temperature
  • Particle size/Particle size distribution
  • Particle shape
  • Cake washing
  • Drying of the filter cake.

BHS’s Autopress technology can conduct filtration, cake washing, pressure and vacuum drying all in a contained environment. Cake discharge is complete. There is no residual liquid or solid heel, which is an important benefit for air-sensitive and toxic products.

Application of filtration techniques
Filter plate

Understanding Autopress Technology

This fully enclosed filter press, with circular filter plates, allows flow in forward and reverse directions. The filter plates (which can use synthetic or metal media) are contained in pressurized filter housing with a gas-inflated membrane sealing the annular space. Thus, all operations are contained from full vacuum to 150 psig.  

The operation of the AP Filter begins with slurry filling to form thin filter cakes of typically 5 – 25 mm thickness.  Pressure filtration continues operating up to 8 barg.  The cake can then be mechanically compressed to eliminate cracking to ensure maximum washing efficiency in the forward or reverse direction.  Finally, the cake can be pre-dried or fully dried either by vacuum or blowing gas through the cake. Gentle drying without agitation or tumbling is especially important for fragile crystals and thixotropic cakes.  Elastomeric knives sequentially and automatically discharge the circular cakes after which the filter begins a new cycle. 

Read more about this topic in an article I wrote for PharmaChem. My take-away is that with close collaboration between the client and the vendor, we can do the kind of creative problem-solving that applies the separation technique needed to achieve production objectives.

Becoming Uncomfortable in 2019

leaders in filtration technology
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Welcome to 2019.  

This blog marks the beginning of Perlmutter Unfiltered’s 5th year; it’s been fun writing and hearing from friends, colleagues, customers, and others from all over the world. I hope my mix of topics — innovation, leadership, and technical insight — have inspired you professionally and personally. 

Thinking about 2019 and preparing for another great year put me in mind of an interesting Fast Company article about what we can do to improve our work space.

Everyone gets comfortable at work, from where we sit and who we prefer to work with on our projects and teams.  As leaders in filtration technology, we look for “no-drama” days in which the process is optimized, production is overcapacity, and customers have no machine issues.  However, these calm and steady-state environments can lead to complacency and learning plateaus. On the flip side, when we experience periodic disruptions, we develop new views and new ideas.  

Therefore, for 2019,  I suggest “becoming uncomfortable.” Shake up projects, teams and tasks/responsibilities. Sit somewhere new. Push yourself personally and professionally to embrace change.

Becoming Uncomfortable

First, step-up to new roles and look for new responsibilities. This could be as simple as becoming an expert in distillation or solid-liquid separation (contact me and I can help you!) or developing expertise on a specific process at your company.  

Next, constantly challenge yourself to get better… call a vendor for a “lunch & learn” seminar, call a new customer and more importantly, make a call rather than sending an e-mail or text. The act of picking up the phone often makes us more uncomfortable in this digital age.

Going further, make small changes every day. A small change is easy to make and before long, the team, the process, the office will see improvements.  Working for BHS Filtration, we say, in German, eins bei eins (one by one) or as I like to say “millimeter by millimeter.”

So, let’s all become more uncomfortable in 2019. Make proactive changes rather than reactive.  Let me know your ideas on this, share your successes, and we can all learn to become uncomfortable together.