Chemical Engineers & Our Superstitions

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Superstitions surround us: Touching wood? Carrying a rabbit’s foot? Collecting lucky pennies? Not stepping on any cracks? The list goes on and on. 

On one of my many chemical filtration business trips (many people have superstitions making flights safer), I read an interesting article on superstitions in the Wall Street Journal’s (WSJ) Magazine. Six luminaries from different walks of life — photography, acting, cooking, writing, directing and music — weighed in. But, alas, there were no chemical engineers.  So, I thought I’d remedy that in a blog. 

The WSJ article featured various thoughts on superstitions. Some defined superstitions based upon religion and culture passed on from many generations. Another outlined a simple ritual such as “when hearing the title of a Scottish play, one would run outside, turn around three times, then knock on the door to come back inside the theatre.” Then, there were “routines” to keep your days identical (i.e. the same workout, the same coffee, etc.). Others talked about superstitions as an attempt at “having control of what you can control.”

However, the one overriding theme, as photographer Gregory Crewdson stated, is that a belief in superstition “comes down to order” and wanting “to clear your path of unknowns.”  

Clearing the Path for Chemical Engineers

So, how does all that relate to chemical engineering?

If you accept Crewdson’s view, all chemical engineers are superstitious. We are always trying to clear our paths of the unknown. In every chemical filtration process, it is the unknowns that give us the most headaches. Why does the pump keep plugging? Why does the filtration system not produce a clean filtrate? Why is the process not meeting the production rates?  The questions we face are endless! But our job remains the same, we must “clear our paths of the unknown.”

Regular readers will know where I’m going with this…Test! Test! Test! Testing is our way of answering questions in controlled environments. To develop a process or troubleshoot an existing one, we need to ask the correct questions, think critically, walk around the plant, etc.  

Contact me with your superstitions for solving critical filtration and drying applications.  Let’s have fun exploring what we all do in chemical filtration.  

Inventive Filtration Technologies for Palladium Recovery 

 

Palladium Recovery
Palladium image source

Many times we encounter an “if it ain’t broke don’t fix it,” mentality. Process engineers in particular run up against this constantly. Yet, when it comes to palladium recovery, we’ve seen some strong results from taking an inventive approach to the filtration technologies uses. Currently, in recovering palladium catalysts the slurries are clarified with the use of filter presses, manual plate or nutsche filters, bag filters, or cartridge filters.  

All of these require manual operations for cake discharge and cleaning between batches or campaigns. Other drawback include: 

  • high labor and maintenance costs
  • high disposal costs 
  • exposure of the operators to toxic and hazardous solvents and solids 
  • environmental impact of used and contaminated filter cloth, bag filters and filter cartridges.  

A new approach developed by BHS uses Pressure Plate Filters, which are batch-operated, pressure-filtration systems. Here’s what’s involved.

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Pressure plate filters are comprised of filter plates, contained within a pressure vessel. The vessel contains the circular horizontal filter plates in a plate stack. The slightly sloped plates are conical-shaped metal that support a coarse-mesh backing screen covered with filter cloth. An opening in the center of the plate allows the filtrate to travel between plates and out of the vessel. 

The slurry enters the bottom of the vessel and is pumped upward. The solids build up between the plates, while the liquid flows through the core of the filter plates and exits from the top of the vessel. The cake is then washed and dried. Two unbalance motors vibrate the filter plates to dislodge the cake from the filter cloth so it can be discharged. 

Pressure plate filters are used for filtration of cakes greater than 20 mm thick. They are selected for cakes that are stable horizontally because of the orientation of the plates. 

Palladium Catalyst Filtration, Washing and Drying 

There are many choices of technologies, but we’ve found pressure plate filters provide higher quality filtration. In one application, manual filter presses were used to recover and reuse the palladium catalyst. The filter presses exposed the operators to the process and had inefficient washing and drying. The process had a very short cycle of 4 hours per batch.

However, when the BHS pressure plate filter technology was implemented, the filtration, two-step cake washing, nitrogen blow drying and cake discharge were all completed in less than 4 hours with full containment.  Read the full article to learn more.