Recently, I discussed the five management lessons that we can learn from the Apollo lunar landing in 1969. Continuing on this theme, an article in The Chemical Engineer, “Houston-We have a checklist” a UK magazine that I write for, had an interesting take on the lunar landing and engineer checklists. I was intrigued, of course, as I periodically invoke Sherlock Holmes and the benefits of checklists for testing, analysis, etc.
The magazine article, written by Mark Yates, looks at the checklists used both at Mission Control and in space. He takes us through the Apollo missions where there could be two spacecraft both operating remotely 240,000 miles from Earth and out of communications contact with Earth for significant periods of time.
Checklists and cue cards covered everything from mission rules, abort criteria, emergency procedures and activation of backup systems in the event of a total failure of a primary control system for example. These checklists and procedures went everywhere. In fact, each Moon-walking astronaut would have a book of procedures strapped to his left wrist that he could follow out on the lunar surface.
In fact, all of the Apollo crews would each log over 100 hours familiarizing themselves with the numerous procedures and checklists. Apollo 11’s Command Module Pilot Michael Collins called them the “fourth crew member.” These checklists were also one of the first examples of digital computers and man being able to operate together seamlessly. One of the actual checklists used by the Apollo 11 crew is shown below:
Chemical Engineering Checklists
How do we use checklists in chemical engineering? We have many uses for them. For example, if you visit an earlier blog, you’ll find checklists and application details for filtration testing.
As a regular reader of Chemical Engineering Progress (CEP), I was impressed to see its Editor-in-Chief Cindy Mascone writing her monthly editorial as a poem. She mentioned that when she writes for the magazine “accuracy, clarity, and conciseness take precedence over all else.” But that doesn’t mean she can’t be creative too! Her poem got me thinking about common myths about engineers.
We aren’t creative
We lack social skills
We want to fix everything (whether it needs it or not)
We’re quantitative wonks
We are boring (just in case that wasn’t clear from being a quantitative wonk)
We’re not open to new areas of inquiry or interest
Get to know an engineer!
Of course, I beg to differ. I like to think of this blog as one outlet for creativity. Plus, every time we come up with a new solution or problem-solve in a new way, we’re showing not only critical, but also creative thinking.
We may know our numbers, and some of us can be a little socially awkward (but plenty of liberal arts enthusiasts are too). Still, I’d argue that we are generally creative, inquisitive, and downright interesting folks!
And now, because I know you’re curious, I can also share the poem itself:
Ode to the March 2019 Issue of CEP
This month we feature process intensification
One aspect of which may be flow augmentation
Equipment that is smaller or does more than one function
To the old paradigm, PI causes disruption.
The first article tells of three RAPID teams
Whose projects are the stuff of dreams
Microwaves, solar hydrogen, and hydrofracking
Energy-saving ideas, they are not lacking.
A dividing-wall column replaces two towers with one
It changes the way distillation is done
With a smaller footprint and lower capital cost
And on top of that, no efficiency’s lost.
So how do you optimize an intensified route?
That’s what the next article is about
Use this building block approach to process design
And watch your energy use decline.
A digital twin software tools can create
To capture the process’s every possible state
You can study alternatives and run what-if tests
To figure out which option is best.
This issue contains many other things, too
Whatever your interests, there’s something for you
The same can be said of the Spring Meeting which will
Take place in New Orleans and be quite a thrill
Check out the preview after page seventy-four
For sessions and keynotes and events galore.
I’ve run out of space so now I must stop
But if you like this poem, to the website please hop
There’s more rhyming about CEP and its staff
I hope I have made you smile and laugh.
Thank you for coming to read more of my poem
On the website or app that is our virtual home.
The authors who write for this fine magazine
Do it not for the money but to get their names seen
By thousands of people at sites far and wide
For this publication is a valuable guide.
The topics they cover in their technical articles
Range from safety and computers to fluids and particles
From water and energy, from bio to dust
From nano to columns that are resistant to rust
From instrumentation to exchangers of heat
Among chemical magazines, CEP can’t be beat.
Our readers know not what we editors do
To make the articles understandable for you
Each page is read over many times with great care
To ensure that no typos can be found anywhere
That tables and figures are in the right places
That all the text fits with no empty spaces
That references include all the necessary data
That symbol font correctly displays mu, rho, and beta
That hyphens appear everywhere hyphens are needed
That the proofreader’s comments have been fully heeded.
We take pride in our work and we love what we do
Bringing the latest technology and information to you
But now we must turn to next month’s content
And make sure every moment on the job is well spent.
2019 is the 50th anniversary of the Miracle Mets World Series-winning season, Joe Namath and the New York Jets taking the Super Bowl title, and the New York Knicks’ NBA Championship win with Bill Bradley. 1969 was quite a time for me as I was growing up a sports fan in Brooklyn. But now that I’m older, I find I’m more drawn to the management lessons we can glean from something else that happened in 1969 — Neil Armstrong, Buzz Aldrin and Mike Collins landing on the moon.
In July, a Businessweek story presented five management lessons we can learn from the “Moonshot.” Although many of us remember the key moments, the history covered at the start of the article is interesting for the controversies we may have forgotten. Nevertheless, the bigger appeal for me is in what we can learn from the Apollo Moon Landing.
Have a clear objective. Author Peter Coy tells us, “President John F. Kennedy vastly simplified NASA’s job with his May 25, 1961, address to Congress committing to ‘the goal, before this decade is out, of landing a man on the moon and returning him safely to Earth.’” That singular focus helped “NASA engineers [to keep] their heads down and their slide rules busy.”
It’s the same in our work environments. If the project has a clear objective from the outset, the operating company, engineering company and vendor teams can all work together to accomplish the project from a technical and budget point of view.
Harness incongruence.NASA had several setbacks with the moon launch. But, as in all science, we learn from our mistakes. We must look at the problem from all angles and, as we know from Sherlock Holmes, it’s important to recognize:
There is no benefit in jumping to conclusions.
Working with others to recreate events can be beneficial.
The need for problem-solving skills such as occasional silence or distancing and learning to discern the crucial from the incidental.
Delegate but decide.This is the essence of leadership. NASA spent over 90% of its budget on sub-contractors. Many of our projects are the same. You need to know when you need help. Then, the project team must have a strong leadership team in place to make the hard decisions, especially when teams are scattered across the world, have different cultures and languages, etc.
Effectiveness over elegance.This is my favorite lesson. I’ve seen its truth often, especially when it comes to the PLC controls on a project. There is always the next best instrument, controller, valve, actuator, human-machine interface, etc. Every engineer wants that his or her project to incorporate the newest solutions, but sometimes a simpler control will allow the operators to manage the process more efficiently. Whether you go for effective or elegant, remember to involve the entire team to make the process safe and understandable.
Improvise. Coy sharesmany examples of how NASA and the astronauts improvised solutions.We have all heard the phrase, “Hello Houston, we have a problem.” On our projects, we need listen to all team members to find the correct solution. Maybe we’ll improvise something that is a little beyond what we know; but this is how technology improves.
It’s amazing to think all of this was 50 years ago but these management lessons still hold true today! Now, if someone wants to share their thoughts on what we can learn from the Mets, Jets, and Knicks’ managers, I’d be happy to walk down that memory lane too!
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!
Being a process engineer is all about making choices. When it comes API filtration technologies, many different types of equipment can be used for removing catalyst residues. While conventional filtration equipment is operated manually, I recently worked with PharmTech on an article outlining how both candle filters and pressure plate filters are operated as automated systems. This article reviews what we discussed.
Pharmaceutical manufacturers are increasingly looking for automated equipment with in-line process control. Well, automated candle and pressure-plate filtration equipment for removing catalyst residues from API slurries are operated in a closed system. This automated filtration also meets the demand for improved safety and reliability by removing the manual operation.
Conventional or traditional filters can be defined as bag filters, cartridge filters, manual plate filters, and plate and frame filter presses. These are all manually operated filters. They are not really sealed—especially not when solids get discharged.
Candle filters and pressure plate filters are improvements over these types in terms of reproducible quality, multiple process steps, cleanable and reusable filter media, and full containment for solids recovery.
A major difference is that the operation of plate filters and candle filters is 100% automated. Solids discharge is provided in a sealed and safe way.
When to Use Candle or Pressure Plate Filters
Deciding between candle and pressure plate filters depends largely upon the cake structure developed by the process solids.
Cake structures that can maintain their integrity in a vertical form are suited for candle filters. If the cakes themselves are too dense or too light or tend to crack, a horizontal plate filter is the better choice of technology. Thickness of the cake structure is another decision parameter. Candle filters typically have maximum cake thickness of 20 mm, while plate filters can handle up to 75 mm.
Generally, the candle filters and pressure plate filters can be used interchangeably based upon the cake structure itself. Some cakes can be handled in either vertical or horizontal form. In that case, the process dictates the choice.
When it comes to deciding the best filtration type for continuous or semi-continuous processing, consider the upstream and downstream equipment. Both candle filters and pressure plate filters are batch operations. For continuous or semi-continuous operations, either multiple units are required or buffer/holding tanks can be installed.
Pharma Disposal or Recycling
We also discussed best practices for disposal or recycling. For non-hazardous disposal, the cakes can be first washed to remove all of the toxic or hazardous compounds and then dried to a standard of no free liquids. The cakes can be fully discharged in a contained and dust-free manner to totes or drums.
For recycling, the process solids can be reslurried within the candle filter or pressure plate filter to be pumped back as a slurry to the process. The process liquids or filtrates can also be pumped back to the upstream reactors for reuse.
Questions about alternative API filtration technologies? Other decision parameters I didn’t think about? Let me know, I’m always ready to chat.
A new year is a great time for a shift in direction. This blog tries to be different each time. I cover topics ranging from innovation to technical leadership. I’m always looking for fresh ways of doing things in our industry, in process engineering and business development. And I look for new ways to convey these ideas to the marketplace.
We have a chance for the next decade to be a new roaring ‘20s. Don’t get stuck taking the same routes you’ve always been traveling. Try these approaches for a novel approach to 2020 and beyond:
Adopt a positive mindset and see the opportunities
Its easy to get bogged down when a process is not working or a project is going sideways. Learn to accept – everything from setbacks through to challenges. Turn these diversions from your plan or expectations into opportunities.
Be brave and stick to your guns
Maybe you are the innovator with a new idea of how things should be done. If you are sure about the design or process change, then go ahead and make the change.Remember, to test first and to have all of your facts in place to show technical leadership.
Make room for your own creative projects
No matter your work focus, set aside time for your own projects.Take one hour each morning (for me after yoga) and before you check your e-mails for your personal projects; this will pay off greatly in the long term, on many levels.
Don’t let the pressure or threat of failure or competition hold you back
Be confident in your work and don’t be afraid to try something different. We always learn from our mistakes, and from getting out there and gathering more information. With greater knowledge comes greater confidence.
Be authentic and believe in yourself
Use more of your judgement and less of other’s opinions. As I have written in the past,learning never ends. And if you try to be what other people want of you, instead of being authentic, it can have negative impacts both on your professional life and personal well-being.
Accept that personal progress can take time but perseverance counts
Any goal takes time.As loyal readers already know, I sometimes mention my yoga practice, which includes headstands, shoulder stands, tripod stands, etc. These did not happen overnight. But by persevering and keeping an eye on small moments of personal progress along the way, I was able to stick with it and see greater success long-term.
Let’s get ready for 2020. I’ll continue working on this blog and providing new BHS and AVA technical and innovative insights on, Perlmutter & Idea Development. As you start anew in this fresh decade, I hope you’ll keep reading my blog and my LinkedIn posts. And don’t hesitate to let me know your ideas about technical leadership and other areas of interest for this blog!
One key element of innovation success is taking risks. I’ve recently read two articles where major breakthroughs in human health started with innovation risks. The two stories are a great reminder that we need to step up to challenges and look at the world anew to innovate!
In our first case, from Business Week, a chemical engineer named David Whitlock became interested in biology after a tubby date asked him why her horse rolls in the dirt, even in the cool springtime months before the biting insects have even hatched. Whitlock was curious too. So he started reading scientific papers and came across a “bacteria, found in soil and other natural environments, that derives energy from ammonia rather than organic matter.”
Whitlock’s took risks for his research. In 2009, he moved into his white Dodge Grand Caravan to study the bacteria culled from soil that he theorized could improve skin disorders, hypertension, and other health problems. And even he’ll admit there were some times he really smelled while experimenting with his soil-based concoctions on himself.
Still, his innovation risks led to the ground-breaking discovery that these ammonia-oxidizing bacteria (AOB) can transform sweat into something more useful. His company now generates almost $2.6 million revenue in cosmetic sprays, shampoos and moisturizers. Microbiomes, “commensal, symbiotic and pathogenic microorganisms that literally share our body space” are now the focus of many new products. The third annual Skin Microbiome Congress, for instance, welcomed established brands such as BASF, Bayer, Coty, Merck, Nestlé, L’Occitane, L’Oréal, and Unilever.
The article is a great example of a single researcher’s drive and creativity. He didn’t shy away from the tough stuff in pursuit of innovation.
An Eye-Opening Innovation Risk
A second recent Business Week article is further evidence that it pays to swing for the fences. The article is about manufacturer W.L. Gore & Associates Inc., best known for the waterproof membrane Gore-Tex, and how its willingness to “take more chances” has led to its polymers being used in corneal implants.
An obsession with a polymer called polytetrafluoroethylene, PTFE, led William Gore to his discovery of the lighter and yet stronger expanded ePTFE. The polymer is now not only used in waterproof wear, but also in air purifiers, dental floss, high-tension ropes, and stents and surgical patches.
Yet the company was stagnating as competitors introduced alternatives. Gore needed to get ambitious again. When Anuraag Singh encountered Gopalan Balaji in a lunch line at a corporate event, the two natives of India, where corneal blindness is a major issue, asked whether they couldn’t do more with their company’s polymer.
Enlisting others, their team sought to modify the polymer to be transparent and light bending in the same way that the human cornea tissue is in our eyes. Their first attempts fizzled and were shelved until a new CEO came to Gore and encouraged innovation risks anew.
With new seed funding to learn more from ophthalmologists, rethink the design, and reconsider their material choices, their team came up with a new prototype. As a sidebar, I have to applaud thehands-on discovery involved along the way:
“We love putting prototypes and materials on the table,” Singh told Business Week.“A typical meeting would involve the surgeon and the engineers ‘all kind of hunched over: feeling, touching, poking at things.’”
The result? An artificial cornea that may help to solve a pressing human health problem in developing countries. The plan is for continued research and testing the first implant in humans in 2020 with the goal of bringing it to market in 2026. With cornea tissue damage the 5th leading cause of blindness this innovation risk could have a happy ending.
Ultimately, these two examples are reminders that we need to look around, ask questions, and listen to our communities to come up with ideas. Then we need to take those necessary innovation risks!
So, here we go again…intertwining two seemingly unrelated topics — creativity and eight-limbed ocean dwellers — in one interesting blog.
Over the years, as my readers know, I’ve enjoyed discussing fresh sources of innovation. Today, it’s the octopus.
First some technical details: Octopuses have eight arms, round bodies and bulging bilateral eyes. The 300 species of octopuses live in all the world’s oceans, but prefer warmer, tropical waters. They typically only live between 1 and 2 years, but during that time they like to play.
That leads us to the good stuff: These creative, intelligent creatures can problem solve and are masterful mimics. Some species can even change the texture of their skin to better hunt and evade predators. Plus, they all lack a rigid skeleton, which lets them contort themselves into amazing shapes.
Yet how does a creature that can only see in black and white make these changes? They control special cells just under their skin’s surface — chromatophores — which hold pigment andchange color within milliseconds. Controlled like muscles, these cells can help many octopuses “see” with their arms and learn the patterns, colors, and textures of other animals they want to imitate.
Sy Montgomery, author of The Soul of an Octopus shares, “three-fifths of an octopus’ neurons are not in their brain, but in their arms,” which “suggests that each arm has a mind of its own”. These arms have sensory capabilities (smell and taste) as well as reach, and can even continue to grasp if severed from the body.
Wile. E. Octopus Creativity
The octopus is a living example of the sentiment in my first blog of 2019, Becoming Uncomfortable. The octopus is always exposing itself to new environments and facing predators.With creativity and intelligent problem-solving it succeeds. Just as humans need to put themselves out there and expose themselves to new backgrounds, experiences, and more. We can’t blend in like the octopus, so we have to become uncomfortable, but it’s worth it.
There’s also something we can gain from thinking about the octopuses seeing with their arms. Think how humans might engage differently if we could see with our arms?We’d be sure to look at tasks in a different manner when thinking critically about process.
Finally, let’s consider what we’d do with better camouflage. I don’t mean you should wear a disguise at work! Still, what if you were to try to camouflage your thinking. You too can be a masterful mimic to problem solve or put yourself in the shoes of the client: “I am not the sales engineer but the lead process engineer” or “I am the Director of Capital Purchasing” or “I am the entrepreneur who needs advice for a process solution while spending my own money.”
We’re still stuck with bones, so we can’t morph into all the different shapes this amazing creature can manage. A 600-pound octopus can get through a pathway the diameter of a quarter! Yet, the octopus’s sense of adventure also underlines my suggestion to get out into the world and see what’s going on for a new perspective on process solutions and life in general.
I hope you’ll have some fun with this and think about the octopus next time you want to be creative!
Normally, as my readers know, my blogs cover a wide variety of topics. I like to relate and link seemingly unrelated topics to each other in innovative ways. It keeps our critical thinking faculties sharp! However, this blog deviates from the pattern to share two fresh viewpoints on changes in engineering standards. It’s technical, but important. Science textbooks will need to be rewritten!
It doesn’t happen often, but after a November 2018 vote at the Congress Chamber in the Palace of Versailles, four fundamental units of measure have been redefined. An assembly of metrologists (those who study the science of weights and measures) voted to redefine the International System of Units (SI)’s ampere, kelvin, kilogram, and mole.
These four units join the meter, candela, and second in being defined not in reference to physical artifacts, but in reference to fundamental physical constants. Scientists say redefining these units to be based on a physical constant will make measurements more accurate and stable.
Science students may not be too happy about having to pay for new science textbook editions, but the unanimous vote was followed by a standing ovation by the assembly’s participants from over 60 countries.
Engineering Standards Must Be Correct
The news was followed up by a Wired blog by Rhett Allain, an Associate Professor of Physics at Southeastern Louisiana University. He agreed the “definition-based standard” was a better choice:
There is a new standard in town, and it’s sort of a big deal…It replaces the old definition of the kilogram that didn’t even have a definition. The old kilogram was an actual object. It was a cylinder made of a platinum alloy and it had a mass of 1 kilogram. It was THE kilogram. If you wanted to find the mass, you had to take it out and measure it. You could then use it to make other kilograms.
He was behind the new standard of defining the kilogram using another constant—Planck’s constant (the details are in the Wired story). However, Allain also cautioned that there is a wrong way to define the kilogram. “Unfortunately, I have already seen some very poor explanations of this new definition of the kilogram,” he wrote. His fear, he wrote, was that “these super-simple (and technically wrong) explanations might become very popular.”
For example, he cites an example: “The new definition of the kilogram sets it equal to the mass of 1.4755214 x 1040 photons from a cesium atom.” Of this he notes, “That is so bad. I’ve even seen a diagram with a traditional balance. On one side there is a kilogram mass, on the other side a bunch of photons. Please help; please don’t share that kind of stuff. You might as well just say ‘Oh, hey—the kilogram is now defined by some magical spell.’”
This is an edited version of an article I wrote for The Chemical Engineer. I hope you enjoy this take on automated clarification technologies.
Throughout my career in the solid-liquid separation market space, I have seen some interesting solid-liquid separation solutions. At one melamine resin facility, the slurry was in a formaldehyde process. The operators were wearing masks, opening up a manual plate filter in a room with residential floor fans, to dig out the cake from the paper filter media.
In another case for zeolites, the client had multiple bag filters to clarify the filtrates following a vacuum belt filter. When the filtrates, the final product, remained cloudy, to my surprise, the client decided to add another set of bag filters!
A clarification system is employed after coarse-particle filtration or as a stand-alone system to remove fine particles at low concentrations. These particles are typically less than 5 µm and are in concentrations less than 5% solids down to ppm levels.
Process engineers struggle to clarify process liquids. But there are ways to automate the clarification processes to improve filtration and minimize operator exposure. The cake solids structure and the nature of the process will determine which types of pressure-filtration, automated clarification technologies are best for you.
A candle filter is a pressure vessel filled with tubular filters (called filter candles). A typical filter candle comprises a dip pipe to flow the filtrate and pressurized gas, a perforated core with supporting tie rods, and a filter sock.
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, a feed pump or pressure from the reactor or feed tank 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 maximum filtration time is reached. The cake is washed to remove impurities and residual mother liquor, and then dried by blowing gas through the cake. Next, low-pressure gas enters 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. Candle filters are used for thin-cake (5–20 mm) pressure filtration applications. They are best suited for filter cakes that are vertically stable.
Pressure Plate Filters
Like the candle filter, pressure plate filters comprise filter elements contained within a pressure vessel. However, instead of vertical filter candles, the vessel containshorizontal filter plates. These elements are slightly sloped, conical-shaped metal plates that support a coarse-mesh backing screen covered with filter cloth.
An opening in the centre of the plate allows the filtrate to travel between plates and throughout the vessel. The filter cloth can be synthetic, as in the candle filter, or metallic as the cake discharge is by vibration or spinning.
Operation is similar to that of a candle filter. For cake discharge, there are two main designs. In one, two unbalanced motors vibrate the filter plates to dislodge the cake from the filter cloth. In a second design, the plates spin so that the cake can be ‘thrown’ off the plates. Pressure plate filters are used for filtration of cakes up to 75 mm thick.
Sintered Porous Metal Cartridges
Another type of automated clarification technology is based upon sintered porous metal cartridges. These can be used in a variety of process flows such as inside-out filtration. After each cycle, solids are backwashed off the inside of the elements and discharged as a concentrated slurry or wet cake. They can also operate in a conventional outside-in filtration. Porous metal cartridges are used for high temperature applications greater than 200oC where the solids are well-defined hard crystalline shaped.
Filter aids are generally the last resort. Often in clarification applications, the solids are very fine or amorphous, so can be difficult to filter. When filtered, the solids will create a thin, impermeable coating over the filter media and immediately reduce the filtration rate to an unacceptable level. In these difficult cases, filter aid pretreatment can be used to improve filtration properties and efficiently remove the fine solids from the process liquids. The types of filter aid include diatomite, perlite, and cellulose.
In the precoat method, filter aid is used to generate a thin layer of solids on top of the filter media. Once formed, the filter aid cake functions as the primary filter media. Therefore, the filter cloth is no longer the real filter when precoat is used. For that reason, the filter cloth should be as open as possible while still retaining the filter aid material.
The precoat process is achieved by mixing the filter aid into clear liquid or mother filtrate in a precoat tank. This slurry is then recirculated through the filter where the solids are captured by the filter media. The clean filtrate is recirculated back into the precoat tank. The precoat should be thick enough to ensure that the entire media surface is coated but thin enough so that it does not provide significant resistance to filtration.
In body feed filtration applications, the filter aid is blended with the slurry feed either by dosing the concentrated filter aid suspension into the slurry feed with in-line mixing or by mixing the filter aid into the entire slurry batch and maintaining agitation. By adding filter aid into the slurry feed, the resulting filter cake is more porous, allowing higher and longer sustained flow rates. Body feed also helps to restrict solids movement which improves filtrate clarity.
Needless to say, the use of filter aid improves filtration but requires more equipment, more process control, and results in more solids for disposal.
Final Thoughts on Automated Clarification Technologies
How can the process engineer be successful? When confronted with a clarification process, don’t simple throw more bag filters at the problem. Conduct lab testing to analyze the cake structure, filter media, filtration pressure and cake thickness. With the data in hand, you can evaluate the different technologies and design a more reliable and cost-effective clarification process. Find a different approach!