Changing from Batch to Continuous Processing

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Our approaches to process engineering must always be evolving. Otherwise, we’ll never grow and innovate. Recently, I contributed a feature to The Chemical Engineer on making the change from batch to continuous processing. Here's an edited version of that article for my loyal blog readers. 
As there is a push to become more efficient, many process industries have begun thinking about continuous processing. Many specialty and fine chemical operations are batch operated. It is easy and typically uses filter presses, vacuum nutsche filters, filter-dryers, plate and leaf filters, and batch centrifuges. 
Yet batch processing significantly lacks flexibility in scaling capacity, and typically requires larger manufacturing footprints and less efficient use of space. So, I’ve been seeing more of a shift from batch to continuous processing. 
In my career, I’ve helped engineers move to continuous operations for such applications in pharma and biochemical, specialty polymers, starch and cellulose, aromatic acids and fly ash wetting.
Why? In continuous processes: 

  • a filter is typically one-third the size of a batch filter
  • the process can increase yield and optimize quality
  • there are fewer reslurry/holding/buffer tanks
  • transfer pumps can be eliminated
  • complications from solids handling can be minimized
  • less agitation is used (which can impact crystal size and fines generation)
  • it can be easier to maintain constant flows, pressures and temperatures

Applications of Continuous Processing

In the article, I shared several examples of continuous processing applications in my career. I’ll recap a couple of them here too.
In a specialty chemical polymer application, a client wanted to transition to continuous processing to eliminate solids handling and reslurry tanks. Eliminating the liquid ring vacuum pump required for vacuum filtration would also cut energy costs. At BHS Filtration, we did lab and pilot testing to determine the rotary pressure filter was the best option.The continuous pressure filter saw a 16% increase in filtration rate; maintaining the temperature at -5oC resulted in a higher capacity. Secondly, we saw a more efficient washing due to less cake cracking in the thin cake (5 mm) as compared with 150 mm (6-inch) cake. 
For a pharmaceutical client, BHS was involved with a transition to fully-automated continuous processing in extracting phospholipids from egg yolk for preparation as a pet food additive. After consulting with the client and testing, the choice was a continuous-indexing vacuum belt filter for vacuum filtration, cake washing, and dewatering of the cake. The technology is based upon fixed vacuum trays, a continuously feeding slurry system, and indexing or stepwise movement of the filter media. In practical terms, the operational features of the belt filter can be viewed as a series of Buchner funnels. Making that change to the filter validated, as a GMP installation, for pharmaceutical production has increased the yield of the phospholipids by 3–5%. 
 In doing this kind of work, we’ve run into different challenges. We’ve been reminded that process scale matters and what works in the lab may not work in the plant. We’ve seen the need to silo both batch and continuous processes in the same line as a continuum. We’ve been reminded of the need to understand how one upstream decision will impact downstream processes.
We must also remember making the transition from batch to continuous processing requires more than just new equipment. The entire manufacturing operation and the mindset of staff need transformed. 
Process engineers have many choices to transition to a continuous operation. Continuous can be more challenging, but the benefits are there. Just be ready for some unexpected consequences along the way, and always test, test, test!
Of course, if you want to read the entire article, and I hope you will, it’s available! I’d be happy to discuss any of the ideas or possible applications of these insights with you. Reach out to me today!
 


business travel

Road Warrior's First Business Travel after 96 Days    

business travel
Photo by Sheila on Pexels.com

First, let me say that in these challenging times, we all must be diligent in our approaches to our business and personal lives.  My heart goes out to everyone who has been impacted by COVID-19.  To help in my own way, I wanted to offer my recent experience with business travel.
Precautions during the pandemic saw me staying put for the longest stretch of time without travel in over 35 years. Of course, it was good to be home. But the time came to get out and see customers again. My first trip was to Appleton, Wisconsin to visit a customer that I have known for several years for a project that may be funded in the 3rd Q. I thought I would share my experience.
The different travel experience started with packing. I began with all my protective gear. Two N95 masks, two disposable masks, two bandanas (Carolina Panther and The Dead & Company) and one infrared thermometer. Next, what cleaning supplies did I need?  Disinfectant wipes as well as a 12 ounce hand sanitizer; TSA will allow this exception. Finally, sealed googles to fit over my glasses to be used in the airport and airplane. The sealed googles are recommended to help you avoid touching your eyes or face.
Business travel
For the hotel it’s recommended to bring along your own pillowcases. So I packed two. In case the hotel gym is closed I bring along my yoga mat, yoga workout clothes, running shoes and my running clothes. I also throw in my running wind-breaker just in case the weather is a little cooler or rainy.
On the customer visit, I need steel-toed safety shoes and safely glasses. Add those to the pack! Finally, I get to my regular clothes. In the end, a pack that normally takes less than 30 minutes, required 2+ hours and a lot of discussions.
At the airport, with no shuttle buses for long-distance parking, all cars are in the parking deck. Finding a space was another challenge. Once this was accomplished, the TSA checkout point required more time and more space. Finally, the airport and airplane were relatively easy.  The American Airlines “concierge” team was very happy to see me.
Upon landing, the car rental facility also was easy and there were large stickers on each car indicating “cleaned and sealed.” The hotel was also following CDC guidelines with masks, social distancing, cleanliness, etc. So, drinks and dinners in the hotel bar for two nights were fun again. These interactions with the staff and other business travelers are always an entertaining part of business travel.  
As for the business, the visit and meetings were successful. We all wore masks; my temperature was checked. Our lunch was in a large conference room and followed all of the social distancing protocols.  
Oh, one more point. No elevators. I walked every staircase. It’s another thing to keep in mind when you're packing.
So, now I am back “on the road again” (I think that this is a song?) and hopefully to a healthy and successful remainder of 2020. Let me know how you all are doing! What changes have you made to your business travel practices? I can’t wait to see you at the next hotel bar for drinks and dinner.
Stay safe and take care. By having concerns and respect for your friends, families, colleagues, and strangers, we will all make the world a better place.


The Wisdom of Silence this Summer

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Photo by Jill Wellington on Pexels.com

       
2020 has gotten off to a really weird start. Many of us have been working remotely, trying to continue to design projects and meet with clients. But, even in the best of situations, we can lose track of ourselves in the process. Consider the wisdom of silence.
This feeling of being pulled in too many directions at once need not be inevitable. We can find ways to ground ourselves amidst all the chaos. Create moments of stillness where you can.
When silence is intentional, it is valuable and restorative. Check out my blog about Sherlock Holmes and the value he found in taking a moment to just think. The great detective would employ occasional silence and distancing for problem solving. In the BBC’s version they show this when Benedict Cumberbatch retreats to his “mind palace.”
We may not have mind palaces, or even mind sheds, but finding silence can bring us back to our senses. Like intentional breathing, which I’ve written about before, silence is essential to our holistic well-being. Silence is a powerful tool that allows us to take a step back from the atmosphere around us and realign with our intentions and ourselves.

Realigning Intentions — Professionally and Personally

I started the year offering a roadmap for 2020. Now, as a midway check-in, here are my suggestions for what we can do to benefit our personal and work lives.

  1. Listen to the customers.  First, broaden your definition of customer. Customers can be your clients, coworkers, vendors, your family. Listen and learn from their feedback and suggestions.
  1. Be useful.  If you listen, you can be useful. And there’s nothing more rewarding than being of use to others.
  1. Make things faster and simpler. Of course, this can’t be at the expense of accuracy, but try not to overly complicate decisions, tasks, actions, etc. We must strive to reduce complications.
  1. Innovate, don’t imitate. To succeed, we need to continually look for new approaches. We love experiments. They help us think differently.
  1. Give back. At some point in all of our lives, we’ve received other people’s help. Try to give back this summer. This may seem like one more thing to cram into the schedule, but the benefits will outweigh that aspect.
  1. Be honest. Speak in an open and ethical manner. As I’ve discussed before, this may even mean being authentic and expressing anger. It’s better to communicate fully than to let resentments fester or leave frustrations unattended.
  1. Keep learning and improving. Loyal readers know that this is a key point for me.  There’s (always) plenty of room for improvements and innovation. That’s how we create better experiences for all.  

As the start of summer approaches, let’s set aside time to tune out the noise. Turn off your device. Go for a walk or simply close your eyes. The magic in the wisdom of silence is that we can access it wherever we are — though I’ll be hoping you get to try this somewhere you love in the coming months (without the social distancing considerations!).


Contribute to a Holistic Approach to Unit Operations!

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Photo by Andrea Piacquadio on Pexels.com

As the chemical industry changes and becomes more integrated worldwide, there is a need for information exchange. This must include not only principles of operation but practical knowledge transfer. That’s why I have agreed to edit a new book for Elsevier, “Integration and Optimization of Unit Operations.”

As my readers know, in 2015, I published the “Handbook of Solid-Liquid Filtration” with Elsevier, UK. This new project offers up-to-date and practical information on chemical unit operations from the R & D stage to scale-up and demonstration to commercialization and optimization.  

For this exciting and unique book to work, I need your help. I’m currently seeking contributing authors who have skills at each stage of the process from lab-scale/R&D, through pilot plants to full-scale production and finally optimization or as I call it, Putting-It-All-Together, for actual case histories / war stories.  We will also cover decommissioning of plants.

Currently, most books look unit operations, each in a silo.  In this book, at each stage, the information presented differs as the technology and issues faced at the lab scale differ through commercialization and optimization. So, we will move from a silo approach to an integrated – holistic approach.

Why this Unit Operations Book is Needed

This book addresses a need for engineers with a broader training background. In the early 70’s, companies wanted staff with an I-shaped skill level. Someone with I-Shaped Skills is a person with a deep (vertical) expertise in one area and practically no experience or knowledge in other areas. This person is typically known as a specialist.  

Then, in the 1980s, the industry wanted T-shaped professionals. The vertical bar on the T represents strong knowledge in a specific discipline. The horizontal bar represents a wide (horizontal) yet shallow knowledge in other areas. This allows the person to be able to collaborate across other disciplines and acquire new skills or knowledge. 

Yet what we need today, with the rapid proliferation of technological advances and the cross- disciplinary nature of our work, is key-shaped engineers who can address several areas of expertise with varying degrees of depth.  

This book aims to address the needs of engineers who want to increase their skill levels in various disciplines so that they are able to develop, commercialize and optimize processes. The engineers must be able to ask questions of experts to develop creative solutions.

What Can You Contribute?

Contributing authors should be able to discuss unit operations at each stage and then relate how these technology/process decisions impacts the next stage. I am targeting the first draft by the end of the year. I will provide technical guidance and assistance as well as from my associate who is skilled in technical writing along with the Elsevier requirements.

The book will be listed on ScienceDirect, Elsevier and others and chapters will receive individual indexing so they can be searched.

I hope you’re as excited about this opportunity to share knowledge about unit operations as I am! I look forward to hearing from you.


Dryer Selection and Bulk Solids Handling 

 

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Image source: https://www.toolshero.com/decision-making/blindspot-analysis/

Solids handling is not a unit operation. Therefore, it’s not covered in engineering courses. This leaves process engineers struggling to understand the “flowability” of bulk solids. This blind spot is huge. So, let’s talk about dryer selection and bulk solids handling.
Recently in The Chemical Engineer, Grant Wellwood described bulk solids handling as the biggest industrial activity on the planet. The article estimated “that >70% of everything we use or consume involves bulk solids handling somewhere in its lifecycle.”
Mishandled, this process can quickly and efficiently destroy product value, careers, projects and even organizations. Yet, bulk solids flow is often an afterthought once the separation and drying equipment is selected. This article aims to bring bulk solids handling to the forefront.

Bulk Solids Handling Parameters

Bulk solids are defined as materials (solids) handled in various volumes and counts. Their flowability is impacted or controlled by friction (particle-particle or particle-surface). During the drying process, solids go through different phases such as free moisture, bound moisture, thixotropic and finally (and hopefully) free flowing.  
The selected dryer must be able to handle each phase without creating fines, balls that can trap liquids, and without adding additional heat due to friction.  
Here are some of the process and design parameters engineers need to consider for dryer selection:

  • Dryer Process: Batch, Continuous, Atmospheric/ Vacuum, Turbulent, Gentle, Ring-Layer, Feeding  (Volumetric or Gravimetric), Upstream and Downstream Equipment
  • Recipes: Number of ingredients, Frequency of campaigns, Cleaning operations, Product integrity (fines generation) after drying and  Residence time
  • Dryer Performance: Batch size, Filling levels, and  Production volume
  • Product Characteristics: Quality, Bulk density, Tendency of segregation & agglomeration, Thixotropic phase, Shape, Size, Homogeneity, Risk of separation, Flow properties, Abrasiveness, and Moisture & Temperature
  • Mixer design: Material of construction,  Surface quality, Heating/cooling, Liquid feeding, Type of mixing tools, Speed of mixing tools and degree of back mixing
  • Dryer Integration: Material flow, Physical space, Process sampling, safety requirements, etc.

It’s a lot to think about. Westwood observed in his thorough article, “When handling bulk solids, it’s always important to take a holistic or systems view because of the complex dependencies.”

BHS & Bulk Solids Handling

As my readers know, BHS provides for thin-cake filtration, cake washing and dewatering based upon pressure or vacuum, for batch or continuous operations from high solids slurries to clarification applications with solids to 1% and trace amounts.  
In 2018, BHS acquired AVA mixers and dryers based in Herrsching (Munich) Germany.  VA is in the unique position to provide both vertical and horizontal technologies providing for turbulent as well as gentle mixing, reacting and drying of wet cakes, powders and process slurries. The technologies are vacuum or atmospheric, batch and continuous, for final drying to “bone-dry” powders. The BHS technical article, Dryer Selection, explains the designs as well as selection parameters.  
We know that solids change when processed from a wet-cake to bone-dry powder. Process engineers need to do the tests and trial and error to better understand these changes. As I often say, we can’t jump to conclusions.
Our process engineers would be happy to help at the BHS test center. With an understanding of how the flow properties change, depending on “complex interactions between particle size and distribution, moisture content and distribution, process history (time and manner), mineral composition, surface texture and condition as well as ambient conditions, just to name a few…” the dryer selection can begin in an educated manner. 
Good luck and feel free to contact me for help with your bulk solids handling questions.