As we announced in March, BHS has acquired AVA-GmbH. The AVA technologies provide for turbulent mixing, reacting and drying of wet cakes as well as powders and process slurries. The vertical and horizontal technologies are vacuum or atmospheric, batch and continuous, for final drying to “bone-dry” powders. They are an essential part of our “Continuum Approach.”
What do I mean by that? This blog briefly reviews our first ground-breaking study showing the benefits of a “Continuum Approach” to final drying and upstream solid-liquid filtration, cake washing and dewatering.
Most often when analyzing a new process development approach, engineers take a “silo” approach and look at each step independently.Our article illustrates that by taking a holistic approach and looking at each step not individually but as a continuum, the process solution becomes much more efficient.
In the manufacturing of the specialty chemical involved, the crystals coming from the reactor in a methanol slurry had to be filtered, washed and dewatered and then dried to a final moisture of less than 1.0 (<1.0 %).The standard approach would be to first look at the solid-liquid filtration step and optimize this step for the maximum washing and drying efficiency. Then, with this information, we’d optimize the downstream drying.The operating company, however, took a different approach and looked at the process as a continuum from solid-liquid filtration through cake washing and dewatering to final drying.The Continuum Approach” resulted in operational energy and nitrogen savings as well as lower capital and installation costs for a more efficient and reliable process.
You can read the full technical article, but the overall result was a 50% decrease in the filtration area, elimination of a nitrogen recovery system with a 30 minute increase in batch drying time at a lower temperature for better product quality.
Contact me to optimize your current drying and filtration process.Let’s get more efficient together!
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
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!
Engineering these days requires agility. We’re reconfiguring processes, and we need to be flexible with time zones, languages, accents, engineering cultures and operating philosophies. We cannot always select the people on our projects and must work with various teams to be successful. How do we do this? McKinsey & Company insights into Agile Project Teams provides some interesting insights.
Let’s apply their practical observations from How to Select and Develop Individuals for Successful Agile Teams: A Practical Guide to process engineering.
First, when approaching a new process problem, it’s important for everyone to understand handling ambiguity with agreeableness leads to success. This includes the engineering and operating company teams and technology suppliers.
Processes are complex; there are many choices for the design. I have one project at the moment where the solvents/solids are toxic and hazardous, the solids polymerize immediately, and the operating conditions are severe. There are over fifteen (15) different options for the solid-liquid separation technology design. McKinsey’s research would suggest our project team needs to work through each option while keeping the focus on a safe and acceptable solution.
The guide suggests, Agreeableness means saying “yes, and…” instead of “yes, but.” It’s not about avoiding conflict or blindly agreeing without any thinking. It’s about testing ideas while being open to feedback.
Agility in Engineering Projects
Per McKinsey’s analysis, the agile project team’s focus must be on outcomes. “Agile teams take ownership of the product they deliver. For them, pride in the product (the outcome) sits higher than pride in the work (the process): they know that the process can and will change as they review the relationship between the process and value it achieves.”
Each step in the process moves the team closer to the desired outcome to achieve the overall objective: optimum technology selection to achieve quality while meeting environmental and safety requirements.
Finally, everyone must work as a team on successful agile projects. Sometimes different agendas must be reconciled. Neuroticism can be an obstacle: “team members need to be able to stay calm when unexpected errors and issues arise.”
Find ways to foster a cooperative spirit. Years ago, I worked on a project where the operating company implemented a program rewarding team members that came up with ideas or creative solutions and showed cost savings. In fact, our vendor team was rewarded for including a special type of dust filter to capture solids from the vacuum dryer. As you can imagine, it’s not often the operating company provides additional compensation to the vendor!
The McKinsey study concludes, “great teams do not mean technically the best people or the most experienced.” Agility serving a shared focus on the goal can make the team even better. Next time, you’re on a project, keep these points in mind. Let me know if you are successful!
P&IDs are par for the course in process engineering. Recently, I was poring over P&IDs and process planning for several projects. Each project was multinational, multicultural, and extremely complex. For one specialty chemical filtration application, part of a plant expansion in the southern United States, the engineering company is in the Southeast while the existing processes were from the Netherlands and Austria. In another project, with a similar scope, the plant expansion and the engineering company were both in the Northeast U.S., yet the current processes operate all throughout the UK.
As you can imagine, the piping and instrumentation diagrams (P&IDs) had many changes, each shown in a different color —the Christmas Trees of P&IDs.There were extensive e-mail threads of comments and questions and, of course, questions/comments about the comments/questions. Plus, the projects required equally fun conference / video calls accounting for time zone differences, various languages and accents, and varied engineering cultures and operating philosophies. You’ve been in this situation too, I’ll bet.
The discussion, though, is invigorating. The idea exchange goes well beyond solid-liquid separation to encompass types of valves, types of pumps, where to put the pumps, how to handle the solids, operator safety, disposal, and on and on and on.I even had a question about desalination and how to operate the DAF (Dissolved Air Flotation) units (that’s a topic for another blog).
Developing A New Process Path with P & IDs
After one of these calls, I had an “A-Ha” moment about the true value of our plentiful rounds with P&IDs and process. This is where the innovation happens. The P&IDs are idea development in action. This is where we, as I wrote in one of my earlier blogs, clear our path of unknowns.
Anyone who’s read my blog consistently will recognize this is what is excites me about process engineering and all we do in this role. I’ve decided to take my own early 2019 advice and stretch myself in new directions with the birth of “P&ID-Perlmutter Idea Development” which you can find at perlmutter-ideadevelopment.com.
To me, these two sites work together like a candle filter functions better with the right filter sock. I’m excited to see how this idea develops, and eager to see what my readers, colleagues, and fellow bloggers will want to add and change and discuss (after all, it’s a P&IDs and process we’re talking about here).
Whether you call it Raney nickel or Raney mud, this alloy of aluminum and nickel is a reagent common to many organic processes. Currently, most Raney nickel catalyst slurries are clarified with the use of manual plate or nutsche filters, bag filters, or cartridge filters.
Yet any of these approaches require manual operations for cake discharge and cleaning between batches or campaigns. At the same time, they accrue high labor, maintenance and disposal costsandexpose operators and the environment to toxic and hazardous solvents, solids and contaminated filter tools.
BHS developed a more contained, cost-effective approach using batch-operated, pressure-filtration systems candle filters.
A Candle Filter Primer
A candle filter is a pressure vessel filled with tubular filters called candles. The candle is comprised of a filtrate pipe, a perforated core with supporting tie rods, and a filter sock.
The filtrate pipe runs the length of the candle and ensures high liquid flow, as well as maximum distribution of the gas during cake discharge. The tie rods create an annular space between the filter sock and the perforated core, which helps maintain a low pressure drop during operation and promotes efficient expansion of the filter sock during cake discharge. The filter sock, made of various synthetic materials, is installed over the candle and can remove 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. 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.
For concentrated 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 cake, which detaches from the filter sock and falls into the vessel cone. The cake is then discharged as a concentrated slurry.
Raney Nickel Catalyst with Candle Filters for Slurry Discharge
In this application, the current process after the reactor is gravity separation, hydrocyclones and then followed with cartridges and bag filters.The specification for the process liquid (diamine and water) is less than 3 ppm catalyst.This recovery process was inefficient and exposes the operators to the diamine and catalysts creating a safety hazard.The average particle size is 2 um and amorphous crystals.
Lab testing and pilot testing was conducted to determine a processing scheme that eliminates solvent exposure, reduces the maintenance and operation requirements of the current scheme and recovers the catalyst to less than 3 ppm.The final design was a BHS slurry-discharge candle filter with 19 m2 of filtration area.
Candle Filters for Raney nickel Slurry Discharge
BHS developed this approach working with a client whose process after the reactor included gravity separation, hydrocyclones, then followed with cartridges and bag filters.The specification for the process liquid (diamine and water) was less than 3 ppm catalyst. The average particle size was 2 um and amorphous crystals. Yet, this recovery process was inefficient and exposed operators to the diamine and catalysts, which created a safety hazard.
BHS conducted lab and pilot testing to determine a processing scheme that eliminated solvent exposure, reduced maintenance and operation requirements, and recovered the catalyst to less than 3 ppm.The final design was a BHS slurry-discharge candle filter with 19 m2 of filtration area. Learn more about this application in this article.
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:
The filter itself for mechanical reasons
The equipment around the filter is not working
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.
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.
With graduation season coming there will be many chemical engineers on the market looking for their first jobs. There are many opportunities with operating companies, engineering companies, startups, venture capitalists (yes, engineers in the financial industry), and consulting firms. Nevertheless, my first choice is sales, so let’s flesh out a technical sales description.
Why technical sales? It’s an interesting field for process engineers for several reasons as you get the opportunity to:
Combine technical expertise with people skills and business knowledge to help customers solve problems
Define customer’s technical requirements
Explain, test, and demonstrate the company’s products to meet the requirements and solve the customer’s problems
Employ a flexible approach to technical/commercial situations
Interact with a variety of people and positions
The best process engineers for technical sales possess a desire to get involved in the business aspects of many different industries/application and are willing to cultivate long-term selling relationships with varied types of people.
But Will I Still be a Process Engineer?
In school you learned all of the technical skills. Now, in technical sales, you use all of your process engineering skills. How so?
Selling requires logical analysis and documentation to the client to make them feel comfortable with the product
Performing calculations allows you to be successful in risk taking and feel confident in your decisions
Continuing to trouble shoot the process and solve difficult problems even after you have sold the equipment
Graduating with the technical skills under control, there are certain attributes that can help you transition to a technical sales role as a process engineer. Those looking to hire you for technical sales will want to see:
Are you a good listener?
Are you motivated?
Do you have thick-skin so that if the client is not satisfied you can accept criticisms?
I embarked on this career path with degrees in chemistry and environmental science and technology. I joined the US Environmental Protection Agency in 1976 when we were a young agency. I did air sampling (clean shaven and no beard) and rule development and was able to learn about many industries and applications. After getting by MBA at night (over four long years), I joined Pall Corporation in technical marketing. This role was fun, creative but now here I am working with BHS-Sonthofen. Some 35 years later, technical sales and marketing are ingrained in my psyche.
Know that you have my thoughts on shaping a technical sales description, let me know if I can help you with your career decisions and training. Good hunting.
Loyal readers of this blog know how much I value innovation and creativity. So, you can’t be surprised that I want to share with you a chemical process optimization success story. We partnered with a client to develop an optimized filtration process for a zinc oxide product.
As discussed in a coauthored article for Chemical Processing, Madison Industries and BHS-Sonthofen Inc. worked together on laboratory and field pilot testing. Engineers from both firms showed creativity and “outside-the-box” thinking in looking at the process from new vantage points in their quest to find a better option than the installed batch filter press.
Our efforts led to the selection of continuous vacuum filtration. The continuous filter, which was installed in 2016, provides maximum filtration efficiency and improves product quality while increasing yield and reducing operating and maintenance costs.
Madison Industries, based in Old Bridge, N.J., supplies copper and zinc compounds such as copper sulfate, copper carbonate, zinc sulfate, zinc chloride, zinc orthophosphate and phosphoric acid as well as other chemical products containing copper and zinc. Applications include animal feed, water treatment, dairy farming, food and pharmaceutical processing, and pool and wood preservative chemicals, among others.
The Madison facility was using a plate-and-frame filter press to filter a zinc oxide slurry made from a mix of various zinc feedstocks. The solids were mixed with water to form a slurry of 20% solids and then filtered. The cake was bagged in 2,000-lb totes, moved to another area of the plant and reslurried in sulfuric acid for further processing.
Madison wanted to expand production and replace the present labor-intensive process with a continuous operation — this led to chemical process optimization.
BHS process engineers began laboratory evaluation of the process. Madison was open to all ideas and formed a team to brainstorm different approaches.
BHS conducted several weeks of testing and evaluated both pressure and vacuum filtration based upon the specific characteristics of the solids and slurries. The testing led to the following observations:
• Filtrate clarity: The most-appropriate filter cloth is a double-weave 12-micron polypropylene.
• Filtration rate: Vacuum filtration produced the maximum filtration flux rate at a cake thickness of 6 mm.
• Cake washing: Maximum displacement washing was achieved with wash ratios of 2.6:1.
• Cake moisture: Although not a critical parameter because the cake is reslurried, cake moisture is approximately 35%.
Based on its creative testing, BHS’s process engineers recommended continuous-indexing vacuum filtration as the optimum option.
Why Continuous Indexing
The BHS continuous-indexing vacuum belt filter provides for vacuum filtration, cake washing, pressing and drying of high solids slurries. The technology is based upon fixed vacuum trays, a continuously feeding slurry system and indexing or step-wise movement of the filter media (see Figure 1). In practical terms, the belt filter operates similarly to a series of Buchner funnels.
At each indexed belt position, washing and drying efficiencies are maximized with the stopped belt and the mechanism of plug flow for gases and liquids. Cake pressing and squeezing further enhance drying. Finally, the fixed trays allow for the mother liquor and the wash filtrates to be recovered individually and recirculated/recovered/reused for a more efficient operation. The design also can integrate steaming as well as counter-current washing.
Madison and BHS installed the vacuum belt filter in 2016. The unit has met all product quality specifications. Madison has realized a 50% savings in wash liquids per batch as well as a reduction in labor and operating costs because the vacuum belt filter operation is fully automatic. Since the installation, Madison has optimized the operation, improving yields and minimizing costs.
The Madison and BHS collaboration illustrates a successful relationship between client and technology supplier. The BHS approach of lab and pilot testing, coupled with idea-generation, fosters identifying the optimal option for critical and difficult solid/liquid separations.
Filtration selection, if we think back to Sherlock Holmes, means “not jumping to conclusions.” There is no “one size fits all” process solution. Selecting a filtration technology requires a systems approach incorporated with other solids processing such as reactors, dryers, solids handling, etc. You could gain an objective overview by filling out an application data sheet (like the ones I use for new or existing applications) that can help identify what’s involved in the specific solid-liquid separation.
Ultimately, the process has three components:
Material properties, which I’ll describe in more detail below
Separation performance objectives including, for example, filtrate quality (conductivity or residual solids) cake dryness, flowability of the cake, crystal breakage /fines generation and conditioning of the cake for further processing
Mechanical properties — The specification must be clear in terms of material of construction, temperatures/pressures, FDA validation, cleaning procedures, manufacturing codes, etc. Each equipment type will have its own mechanical specifications that must be satisfied.
These three considerations are combined and ranked choices are then evaluated for operational, economic, and plant (internal and external) objectives.
Finding the Best Filtration Procedure
Your examination of material properties considers the solids and the liquids. For solids, the engineer needs to know the total suspended solids (TSS) and solids concentration, particle size distribution (PSD), and particle shape. The PSD should be based upon particle counts at different sizes rather than by weight or volume.
The particle shapes can vary: spheres, rounded, angular, flaky, or thinly-flaked are among the examples. Shape will influence the filtration rates for the process and also impact the PSD due to the nature of particle size measuring equipment.
Knowing this, the solid-liquid filtration system further requires a systems approach to incorporate other solids processing such as reactors, dryers, and solids handling, etc. The full scope should include the actual upstream and downstream.
Consider this typical example of a chemical process including all of the associated processing steps:
Chemical synthesis and Crystallization:
Types of catalysts
Continuous or batch
Solids and slurry handling in all steps
General Guidelines to Selection
So, the question is where to begin to make the preliminary filtration technology choices for solid-liquid separation? Here are some general guidelines for selecting among types of filtration:
Continuous Vacuum and Pressure
Nutsche Filter & Filter-Dryer
Solid content of the suspension (%)
5 to 30
10 to 40
10 – 40
Maximum Pressure Difference
-1 to 6 bar
Cake Thickness (mm)
5 to 50
5 to 150
5 to 300
Average Particle Size
1 to 100 micron
1 to 100 micron
5 to 200 micron
1 to 50 micron
Type of Operation
Good for slow filtration and can produce dry filter cakes;
Excellent cake washing and pre-drying
Good when reactor batch times equal to total cycle times
Disposable for low flows; candle and plate filters for large flows
Let me know if this is helpful to you. My idea is to do a series of types of filtration systems for solid-liquid separation for various applications. What is troubling you?
What do “Star Wars — The Force Awakens,” the New England Patriots and the Kansas City Royals and this blog all have in common? As you might have guessed, they all had special events in 2015. Yes, my blog has been up and running now for over three years! Plus, 2015 is when Star Wars debuted and both New England and Kansas City won their respective championships.
Before thinking about 2018, and this blog’s fourth year, I wanted to take a moment to reflect on the year 2017. What intrigues me is what we know now that we did not know in January 2017, one year ago. There were many surprises ranging from politics, world events, social issues, to business and career, sports, food and entertainment. In the comments below, let’s start a conversation about what you learned in 2017.
Reflecting on 2017 and 2018 Success
Of course, I have many ideas about what I learned last year. Yet, in boiling it down to one theme, I would focus on “speed.” In all of our endeavors, the speed of information flow, decision making, world events, politics, etc., is increasing dramatically. From a business point of view, technology, marketplace, competition, manufacturing, etc. are all changing at breakneck speed. At BHS, for example, we addressed a marketplace request to incorporate “clean-in-place” (CIP) systems which led to changes with our rubber belt filter.
At the same time, if speed is what characterized 2017, for 2018 I’ve decided it’s time to slow down and reflect. For one thing, I have improved my yoga practice. In other areas of my day, I’m taking the time needed to review facts and data, analyze decisions, gather inspiration from many sources, and finally proceed with definite actions. Of course, I still need to be ready to change, as things will continue coming at “breakneck speed,” but I am optimistic about success.
For 2018, I’ve already started thinking with excitement about what posts my readers want to read. There will be more blogs about “problem-solving” with topics on filtration, particle technologies, drying, and solids handling. Yet I always invite you to make suggestions! In fact, I’d welcome guest blogger contributions to improve the chemical process industry. Finally, read often, thick critically, and let’s all prosper in 2018.