Offshore Problem Solving

There’s a First Time for Everything

For the first time, BHS-Sonthofen Inc. has gone offshore! The great thing about this as a process engineer has been reminding myself that new challenges demand new processes, and offshore filtration is no different.
Offshore filtration

Working offshore demands a new way of approaching filtration. For a start, the systems need to be more compact and operate automatically, and they should have low maintenance requirements.
In working with monoethylene glycol (MEG) regeneration plants, BHS wanted to find an alternative to conventional methods. For the transport of Liquefied Natural Gas (LNG) in pipelines, MEG is added as corrosion inhibitor and to reduce the freezing point of the water in the LNG. The MEG is then reclaimed. Our goal was to do this in a cost-efficient way while also being environmentally conscious.

Christian Gassen and I noted in a Petroleum Technology Quarterly article that “recovery of glycol is gaining importance. The goal of many operations is for the dried solids for disposal to contain no more than 10% glycol.”

So, while, onshore plants typically use static thickeners such as settling tanks, the resulting sludge typically contains large amounts of glycol. This then requires further use of high-speed separators and decanter centrifuges.

Only those don’t work as well in offshore filtration. Needing trained specialists to maintain the equipment (and frequently) increases operating costs.

Using cartridge filters with deep bed filter elements also increases costs due to the filter elements’ limited self-cleaning properties and time-consuming disposal requirements. Plus, you still need to further process the sludge to remove the glycol.

Looking at ways to offer compact and low-maintenance plants while reducing the residual amount of glycol, BHS developed a new combination process with concentrating candle filters followed by pressure plate filters for cake washing and drying.
Offshore filtration
Our wanting to take a new look at old methods led to a combination process that doesn’t use precoating or chemicals and displaces the residual glycol in the filter cake with water to reduce glycol loss. We also decrease operating and maintenance costs and offer a compact design (saving space is critical when offshore).

This is just another concrete example of the importance of creativity in process engineering. It’s the new ways in which we solve problems after evaluating all filtration possibilities and, of course, testing first, that leads to leaps in efficiency in offering optimum solutions — whether its onshore or offshore filtration.


Rock Stars of Filtration

Whether or not you think our obsession with celebrities has gone too far, you probably have one or two people you admire. They are the rock stars you would be tongue-tied around if you ever met them, or embarrassing yourself by sharing too much about all that their songs have meant to you.

Me? I’m a huge fan of the Allman Brothers, The Who, George Harrison, Bob Dylan, and Warren Zevon. They are my rock idols. But why am I telling you this? I was reading Chemical & Engineering News recently and noticed the Editor’s listing of “Chemists Who Rock.” The editorial borrowed the following list from the Chemical Heritage Foundation:

filtration
Image source: http://www.quimicaweb.net/mujeres_fyq/MUJERES_EN_FYQ/marie_curie/index.htm
  1. Marie Curie (1867–1934)
    2. Antoine Lavoisier (1743–94)
    3. Joseph Priestley (1733–1804)
    4. John Dalton (1766–1844)
    5. Justus Liebig (1803–1873)
    6. Friedrich Wöhler (1800–82)
    7. Dmitri Mendeleev (1834–1907)
    8. Emil Fischer (1852–1919)
    9. Robert B. Woodward (1917–79)
    10. Linus Pauling (1901–94)

After noting that there was no living chemist on the list, and arguing that Frederick Sanger should have made the cut, Bibiana Campos Seijo asked readers to identify living rock stars of chemistry.
This got me thinking about rock stars of filtration. Me, I’d put inventor Dr. David Pall, hydrogeologist Henry Darcy, civil engineer Claude-Louis Navier and mathematician George Gabriel Stokes on the list.

Who would you add? Let me know in the comments below! Let’s generate our own Top 10 for filtration.


Engineers pulling pranks and pints.

We might have a reputation when we’re all grown up of being a dry bunch. But you remember how much fun you had (at least some of the time) as an engineering student, especially when it came to engineering pranks!
Consider these hilariously ingenious pranks. They include students hanging a suspending a Volkswagen Beetle from Vancouver’s best-known bridge back in 2010 in time for the Olympics. Or MIT students turning a campus building into a giant tetris board:

engineering pranks
Image source: www.howtogeek.com

I remembered that kind of light-hearted enthusiasm among engineers when I read this recent infographic from Chemical & Engineering News about the Chemistry of Guinness.
Image credit: Sami Keinänen / Foter / CC BY-SA
Image credit: Sami Keinänen / Foter / CC BY-SA

Now, I love Guinness. But I also admire the brewer for knowing its process so well. If Guinness has a problem with bubbles, they know where to look.
If you have a solid-liquid filtration problem, do you know where to look?
In my handbook, I talk about a specialty chemical application in which testing showed continuous rotary pressure filter would achieve the requirement for filtration, cake washing and drying.  Yet, after installation and startup, the filtration flux rates were completely different and the continuous process steps could not be realized. The engineers examined all of the process parameters, reviewed all data and reaction chemistry, and after several months determined the zeta potential (ionic charge) of the slurry had changed due to the process flow. Agglomeration was occurring in the filtration system within the filter itself.  A small change to the pH finally corrected the process problems while not impacting the reaction chemistry.
Whether pulling a pint or engineering pranks, or testing a process, testing all the angles makes a difference. Now, if we could only get ratings for the systems we use along the lines of the ones employed for beers!


Scaling Up Engineering

A Focus on Scaling Up

“Scaling up” may have new meaning this summer if you’ve seen the blockbuster Jurassic World. Those scientists can’t keep their hands off the dino DNA and engineer one big, bad and nasty scaled-up dinosaur.

Scaling Up process
Photo credit: Foter / CC BY-SA

Yet when we focused on scaling up process in our latest BHS e-newsletter, A&SoF, we were talking about process scale-up for specialty chemicals and bioenergy.
Our own “Process Scale-Up from Demonstration Batch Filtration to Commercial Continuous Filtration” details a process filtration approach developed for each technology stage-gate and emphasizes how to avoid the cookie cutter approach.
Whether at lab, pilot, demonstration, or commercial scale it’s important to train yourself to be a better decision maker. Using checklists, formulas and structured procedures are your best bet.
We engineers are under stress during the scaling up process (as our families at home might attest), yet it’s important to take the time to think about all of the process issues before moving to the next stage. Give your team time to reflect (as Holmes and Watson often did) to insure the premises are sound (process definition, requirements, and testing objectives), you’ve understood the critical process parameters, and to end up with the optimum process filtration solution.
In the newsletter, we also share David Edward’s CEP article about the stage-gate method in bioenergy as he explains differences between traditional chemical process and bioenergy project scale-ups. After all, another good habit of a process engineer is to be well-informed.
Want to learn more about filtration principles? Join one of BHS’ upcoming Lunch & Learn Filtration Seminars or let me know you’re coming to one of my upcoming Presentations. See you there.


Let's Get Rating!

SLS technology
Image credit: .reid. / Foter / CC BY

College Football has its AP Poll, Coaches Poll and the BCS. College Basketball uses the RPI-Rating Percentage Index and Strength of Schedule. Soccer sees teams ranked by FIFA based on their success in their games over a four year period. Plus we use rankings to decide on what restaurant to go to, what beer or wine to drink, what movie to see or rent.. So where is the common standard for Filter Ratings?

Without one standard rating system for SLS technology and filtration capabilities the user can easily get confused. Of course, testing is always key, but I can at least help you understand the four commonly used rating methods.

  1. Nominal Rating — an arbitrary micron value given to the filter by the manufacturer based upon removal of some percentage of all particles of a given size or larger. Since the value is rarely well defined and not reproducible, these ratings have little to no value.
  2. Absolute Rating — gives the size of the largest hard spherical particle that will pass through the filter or screen under specified test conditions. This commonly used rating is an improvement on nominal ratings.
  3. Beta Ratio a simple rating system based upon the ratio between the per unit volume number of particles above a given size in the influent (upstream) of the media suspension to the same parameter in the effluent (downstream) of the filter media.
  4. Air Permeability — the flow rate of air per unit area at a given differential pressure. This is normally expressed as cfm/ft2 at 0.5 inches water gauge. Typical ratings can be from 2 – 2000. Keep in mind, construction factors and finishing techniques have an effect upon air permeability as they can change airflow paths.

If there were one Absolute System when it came to rating, things would be easier, but maybe more boring too. Test. Test. Test. That’s how you’ll really find the best SLS technology option for your project. In the meantime, I'd argue we need to start a dialog about rating systems in the chemical, pharmaceutical, energy, oil and gas industries! What do you think? Comment below.