Changing from Batch to Continuous Processing

batch to continuous processing

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!

 

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.