Novel Filtration Technologies for Pharmaceutical Hydrogenation

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When it comes to removing catalyst fines from pharmaceutical hydrogenation reactions, BHS Filtration has come up with a novel approach.

Currently, most hydrogenation slurries are clarified with the use of manual plate or nutsche filters, bag filters, or cartridge filters. All of these require manual operations for cake discharge and cleaning between batches or campaigns. At the same time, these units suffer from high labor, maintenance and disposal costs as well as the exposure of the operators and the environment to toxic and hazardous solvents and solids, used and contaminated filter cloth, bag filters, and filter cartridges.  

A new approach uses candle filters which are batch-operated, pressure-filtration systems.

Understanding Candle Filters

A candle filter is a pressure vessel filled with tubular filters called candles. The candle is comprised of:

  • filtrate pipe —  runs the length of the candle and ensures high liquid flow, as well as maximum distribution of the gas during cake discharge.
  • perforated core with supporting tie rods —  the tie rods create an annular space between the filter sock and the perforated core, which helps to maintain a low pressure drop during operation and promotes efficient expansion of the filter sock during cake discharge
  • filter sock — installed over the candle, and made of various synthetic materials, the filter sock is capable of removing particles smaller than 1 micron (μm). As the cake builds during operation, the candle filter’s removal efficiency increases, enabling removal of particles as small as approximately 0.5 μm.

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Candle Filter in Action

During operation, pressure from the reactor forces the slurry into the bottom of the pressure vessel. The solids build up on the outside of the filter sock, while the liquid filtrate flows into the candle, through the registers, and out of the vessel. This process continues until the maximum pressure drop, design cake thickness, minimum flow, or filtration time is reached. The cake is then washed to remove impurities and residual mother liquor. Finally, the cake is dried. 

For cake discharge, low-pressure gas enters in the reverse direction through the registers and into the individual candles and expands the filter socks. This process breaks apart the dry cake, which detaches from the filter sock and falls into the vessel cone. The cake can also be discharged as a concentrated slurry. 

Pharmaceutical Hydrogenation Application 

In the pharmaceutical catalytic hydrogenation application, the current process after the reactor is metal bag filters for slurry discharge into manual nutsche “clamshell” filters for vacuum filtration and drying.  The process was time-consuming and required handling of liquids and solids including final “manual dig out” of the filters.  The process solvent was tetrahydrofuran (THF) and ethanol.

Lab testing was conducted to develop a new, one-step process for filtration and drying.  The BHS candle filters with pharma designed candles and cGMP compliance allowed for a revamp of the operation with two filters, one-on/one-off for continuous operation.  Read the full article and let me know what you think!

Application of Separation Techniques & Full Containment

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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.

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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

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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.  

Thinking Critically in Process Troubleshooting

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In past blogs, I’ve talked about reactive and proactive process troubleshooting. Reactive troubleshooting requires quick action to look at mechanical issues, upstream and downstream equipment, and operational procedures.  In proactive troubleshooting, we ask probing questions and walk around the plant to uncover potential problems and offer solutions.  

Dirk Willard, Contributing Editor of Chemical Processing, in his recent article “Read and Think Critically” offered more to think about on this subject. 

Dirk used an example of trying to write a debottling report and discovering several missteps:

  • The product manual was poorly written
  • The plant engineer had not identified what was missing from the manual and what he didn’t understand
  • No logic was applied to decide who would know best how to run the equipment — “the engineer who built it or the process expert who operates it”
  • The engineer could have paid more attention to the section that was more detailed on the topic at hand.

Ultimately, what was missing? Critical thinking! He called for “questioning the value of information, its relevance and validity, the agenda of the source and, most importantly, the logic on which the data are based.”  

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He offered real world examples of critical review, “identifying what’s being done, how it’s done, why it’s done, and who’s doing it” with a paper mill selecting a close-coupled water pump without considering all angles of the decision.

Take a Critical Approach to Process Troubleshooting

I bet you can easily add your own examples. For instance, there always seems to be a question about instrument and compressed air for the process. The process design for valve actuation has one pressure, but the operators know that in normal operation there is high demand. So the instrument air pressure drops and the valve actuates more slowly. Slow actuation results in lower production. Thus, we need to keep in mind the actual conditions versus the design conditions.  

As for compressed air, it used to be “free” at the plant. Not any more. Every plant now considers this a cost of operation. Once again, operators know that during high demand, the air pressure drops. But the process designers may not have considered this. Next time, design in a compressed air tank so that your process can meet the requirements.  

To do your best work, keep thinking, keep reading, and keep asking questions. If you have an area of expertise, let me know; I am always learning and maybe I can use your skills. I’m always interested in learning more about process troubleshooting.

Busyness versus Business and Chemical Engineering Action

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My first blog of 2018 talked about the “speed” of the world and recommended slowing down and reflecting. Well, here’s some free chemical engineering advice as the year draws to a close: It’s important to take the time to review facts and data, analyze decisions, gather inspiration from many sources, and finally proceed with definite actions. Still, you’ll need to be ready to change, as things will come at you at “breakneck speed.”  

In my out-of-the-box way of thinking, I’m going to relate these ideas to the World Cup — Congratulations to France! During the big tournament of the big game in summer 2018, there was a lot of discussion about penalty kicks. 

Bradley Staats discussed them in the Wall Street Journal article “Don’t Simply Dive into Action:  Think.” He looked at various research sources and concluded that “the goalie’s best strategy may be not to move at all.”  At the same time, surveyed goalies have said that they would regret allowing a goal more if they stayed in the center (rather than diving left or right).  This impulse reflects an “action bias.” The idea that doing nothing could be the best strategy for goalies or businesses is seldom discussed.  

Action Bias in Chemical Engineering

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In the world of chemical engineering, when looking at a problem, we are all taught to gather more data, do more testing, investigate more research, get more sources, etc.  And yes, sometimes this is the best strategy when coming across a problem that is new to the plant or to the specific process.  However, there are many different thoughts on this topic from Sherlock Holmes who employs occasional silence and distancing for problem solving to Thomas Watson, longtime CEO of IBM who would tell his salespeople “the trouble with everyone is that we do not think enough…knowledge is the result of thought.”

So, what is the answer?  As we sit at our computers and study the data, we all debate with ourselves whether to take a short walk or brainstorm for 5 minutes.  As the title of the blog states, busyness does not lead to business or to learning.  So, as an engineer, I suggest the brainstorm approach and thinking.  For vendors and sales people too, the tendency is for action.  But, even for sales people, thinking and slowing down to develop the correct approach is critical to success.

My chemical engineering advice is to avoid acting just to show “action.” Instead, take some time to think.  We may have to change Notre Dame Football coach Frank Leahy’s quote to read instead: “when the going gets tough, the tough get thinking.”  Let me know your ideas.

Real World Examples of Particle and Cake Formation Influences

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Process engineers might love it if all of the filtration technology solutions they developed ran flawlessly, at all times, under all conditions. But, this isn’t realistic. Something might go wrong with the filtration mechanism itself. A change in the environment — upstream or downstream — could cause problems with particle or cake formation. Even the smallest shift in the operation process or procedure can prompt the dreaded phone call to the engineer: “the filtration system isn’t working.”

In my work at BHS-Sonthofen Inc., I’ve seen filtration technology impacted by particles and cake formation that weren’t predicted in designing the solid-liquid separation solutions. 

Particle Sizes Changes from Lab to Production

The existing process was a batch crystallizer operating at 0 – 5 degrees C with 13- 20% solids  to a batch vacuum filtration operation. The filter was designed for a five inch cake height. The objective of the process optimization was to move to a continuous process of continuous reaction to continuous filtration, cake washing and drying.

The BHS rotary pressure filter was installed for continuous pressure filtration.  What did the client find out?  Only the particle size has changed from lab to production!  As you can imagine, this was not a small change.

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Going back to the drawing board and testing processes again, we made the following changes to the filtration system:  new filter media, increased cloth wash pressure with a new solvent and finally a reduced cake thickness.  Yes, this trouble shooting required about 6 months of work, but problem solved!

Troubleshooting Filtration Technology

In another instance with grey water treatment units, a clarification application for the purge water treatment unit (PWTU) was installed and started up for a year of successful running. Then, inexplicably, the performance changed and the filter began plugging quickly during cycles.

cake formation

 

Troubleshooting the system we had to re-examine the filtration system under different conditions:

  • Clarifier overflow with no coagulant / no flocculants 
  • Clarifier overflow with only coagulant / no flocculants
  • Clarifier overflow with both coagulant and flocculants
  • Clarifier overflow with only flocculants / no coagulant

Taking a holistic approach to the system, we were able to determine chemical changes caused the larger particles to settle out. Only the smaller particles were reaching the filtration system, which was blinding the filter media.  By eliminating the flocculants  and reducing coagulant usage (even though this was better for the client, and not necessarily BHS as the chemical supplier, we were able to improve filtration rates and once again offer a consistent PSD.

Ultimately, with the right approach to troubleshooting, and by embracing the idea that we do on a daily basis is an art coupled with science, we can enjoy a strong sense of satisfaction when we get that filtration technology up and running again.

This blog is based on a presentation I made to the  8th World Congress on Particle Technology. View the presentation slides in full!

6 Global Trends Driving Filtration and Separation Technology Innovation

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This guest blog by Molly Henry of the American Filtration and Separations Society (AFS), appeared on their site (with my editorial assistance). For those who missed the original, I thought it was information worth sharing again here (in edited form) regarding the global filtration market.

As our population grows and urbanizes, so does our need for clean energy, pure water, increased food supplies, advanced medical care, and improved digital devices and processing power. Filtration and separation suppliers, as an enabling technology to most industries, must continually evolve to increase capacity and improve filtration performance. This blog examines the trends necessitating innovation. 

Population growth will drive demand, which will require increased production and manufacturing efficiency for industrial products, foods and beverages, transportation, and infrastructure. All of which means a greater need for filtration and separation technology.

Rapid urbanization on a global scale requires new and improved infrastructure, including water, power, communications and transportation; all of which require filtration.

Disruptive digital technology changes have dramatically improved computer processing for several decades, and trends call for this to continue. As computer circuits have grown smaller and smaller while increasing in processing power, filtration and separation technologies have also become increasingly more sophisticated.

Natural resource scarcity and climate change will make it increasingly difficult to supply an ever-growing population with clean water. This will drive greater use of desalination technologies. Recycling and reusing of wastewater on a consumer, commercial and industrial scale will become the norm. Filtration and separation technology make all these processes possible.

Transformative advances in healthcare will allow people to live longer, healthier, and more productive lives. A part of this process will be advances in diagnostic and drug therapies, which utilize filtration and separation technologies. At the same time, a focus on a cleaner environment and all natural and pure consumables, will see more industries utilizing filtration and separation rather than chemical technologies to make products safe and pure.

The race to zero emissions and zero discharge for industrial manufacturing, public utilities, automotive and aerospace will be a technology challenge on many fronts. Filtration and separation are among the major enabling technologies for this purify, recycle, and reuse process.

Whatever role you play, keeping an eye on these megatrends will serve you and your constituents well in the quest for long-term growth and value creation in the global filtration market. 

 

Become a Filtration Tech Troubleshooting Expert

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Recently I addressed the too-familiar telephone call that the “filtration system is not working.” When the call comes in — and so seldom during regular business hours —  filtration tech experts have to react quickly to solve the problem.

Now, the question is how do you avoid getting these types of calls in the first place?  Well, you can turn off your cell phone, but maybe isn’t the best idea.  Instead, the better approach is proactive troubleshooting. 

Proactive Filtration Tech Troubleshooting Ideas

As you know, I’m a big fan of Sherlock Holmes. The great sleuth talks about checklists and separating the consequential from the inconsequential facts. This systematic approach works perfectly for troubleshooting — take a systematic approach with a comprehensive set of questions and logic charts.  After all, we all know that most problems, maybe 90% or more, that arise with the filtration system have been experienced before.  

A different approach involves “walking around” or random analysis.  Sherlock and Dr. Watson are also very good at this. They see what’s not there to uncover the facts. This observation approach can help with the unique problems. I’ve written before also about the Japanese approach of “Genchi Genbutsu,” which further explains this option.

Becoming an Expert Troubleshooter

Becoming an Expert Troubleshooter, though, requires developing several “soft” skills over and above your technical expertise and great depth of knowledge in many areas. These characteristics include:

  • Critical thinking: Ask probing questions to everyone at the plant from operators, mechanics, to process and R&D engineers to encourage conversations
  • Excellent communication: Listen to the answers and ask the same questions in a different way or use the answers to formulate different questions and keep an open mind.
  • Empathy: Try to understand potential frustrations.
  • Motivational: Praise everyone who provided you with the answers, ideas, etc. to inspire the plant
  • Ability to teach: Look for teaching moments so problem-solving permeates through the organization.

In the future of work, we’re going to be looking more at talents in addition to expertise. Cultivate your troubleshooting chops. Keep walking around and keep learning. In the meantime, let me know your area of expertise; maybe I can use your skills.

My Thoughts on Filtration Separation Trends and Practices

 

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I recently had the opportunity to share my ideas on filtration separation trends and practices with World of Chemicals magazine. My favorite part may have been the headline, “Aging with perfection in filtration technology.” I like to think they were talking about me — ha ha!

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In the meantime, I thought I’d excerpt some of the thoughts I shared in that interview.

Talking about global trends in the filtration separation equipment market, I noted, as the world’s population grows, there is a need for cleaner energy, improved water & food and advanced health care….Advances in healthcare and pharmaceuticals and nutraceuticals [are also allowing] people to live longer, healthier and more productive lives.

This means, “filtration and separation technology suppliers must continually improve their products to meet these needs. The trends in the filtration market space are two-fold: moving towards continuous filtration (which is more efficient) as well as moving towards finer and finer particle size removal.”

I suspect we’ll see high demand for filtration separation products in “pharmaceuticals with smaller batches, cleanability and multipurpose operations.” Also, “for increased food supply, we see growth in the agrochemical market including fertilizers, pesticides, herbicides and insecticides.” Plus, “cleaner water is driving the specialty chemicals for resins and catalysts.”

As chemical and pharmaceutical manufacturers adapt to more multipurpose facilities, filtration and separation equipment must be cleanable and avoid cross-contamination between products. Batch sizes are also smaller, and we demand for finer filtration and separation to 0.5 microns as well as automatic operation for safety, efficiency etc.

Automation trends & more

Automation technology is one of the most important aspects for customers today. It is critical for filtration and separation products for preventative maintenance, efficient operation, mechanical troubleshooting and process analysis. Applying improved automation technology greatly reduces the energy usage and improves accuracy and precision to the overall process.

Automation also provides for optimum operations, time monitoring systems, report generation and recipe management.

We’re also going to have to incorporate R&D to meet market demands. At BHS, we’re working with clients to combine technologies for full turnkey responsibility to minimize lifecycle costs and reduce operating costs. So, overall, we are focused on innovation, automation, continuous processing, cleanability and overall reliability to 99 percent uptime. We strive to provide complete process solutions with spare parts, service and continually to improve the client’s operation.

This requires testing — of course. “Testing provides the collaboration with the client to provide innovative and cost-effective process solutions.”

At the same time, one big challenge in our market is the need for speed. Speed of innovation is impacting our clients who are developing new processes very quickly using micro-reactors, new chemistry, and new products.

The speed at which the filtration and separation suppliers must operate to meet the clients is even faster. Successful companies must fulfill this “speed” objective without sacrificing any core values of safety, efficiency, quality, and service.

Troubleshooting When the Filtration System is Not Working

 

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These are five dreaded words that no engineer wants to hear on a Saturday night or Sunday morning: “The filtration system is not working.” Of course, we never seem to get this call at 10 in the morning on a work day!

No matter the time of day, let’s not panic, take a deep breath and begin the analysis.  

There are normally three main areas that must be examined when you learn the filtration system is not working:

  1. The filter itself for mechanical reasons
  2. The equipment around the filter is not working
  3. The filter operational procedures are not correct.  

To fully understand the problem, it’s necessary to separate the symptoms from the causes. So, let’s examine each of these groups in more detail.

Troubleshooting Filter Problems

The first thing that should be checked is the filter itself. There could be a failure of the equipment mechanics such an internal components, seals, etc. Many of these issues will be described normally in the preventative maintenance section of the filter’s O & M manual. 

Second, keeping in mind, the filtration system is part of the entire process it’s important to examine the upstream and downstream equipment. For example, you might check:

  • Are the reactors performing correctly in terms of agitation, temperature control, etc. in order to produce the specified crystals?  
  • Are the precoat and body feed systems in tune for mixing, feeding, flow rates, solids loading, etc.?  
  • Are the valves and instruments operating correctly and reading the correct variables (calibrations), etc.?  

Next, take a look at the pumps that feed the slurry and washing liquids as well as the compressors the feed the gas streams for drying and cake discharge.  The pumps must produce the required pressure, flow rates, etc.  The compressors must also produce a certain gas flow at a specific pressure for a certain amount of time.  Are their interlocks in the control system or a control communication problem that are not being recognized that are causing the filter problem.  Finally, if flocculants and chemicals are being used, have these changed?  

Process Engineering Problems? 

The last place to look is the process or operational procedures. These could be responsible for the filtration problems.  For example, the particle size distribution may have changed, the amount of solids in the slurry may have changed, the cake compressibility may have changed, etc.  In terms of the operation, has the filtration pressure changed, timers changes, speed changed, etc.?  Finally, determine whether or not a process parameter has changed.  

Trouble shooting is not easy, but solving the problem brings a great sense of satisfaction. 

Let me know some of your troubleshooting horror stories! I’d love to share some in a future blog. Together, we can make it easier to handle the situation next time we hear those five dreaded words.  

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