When a plant starts having trouble with a fertilizer compound hardening in a mixer and stalling a motor, an engineer finds inspiration in an unexpected placeBy Charles Picek, P.E., Contributing Writer
One of my many jobs as a chemical engineer was at a plant that produced Triple Super Phosphate fertilizer in a batch process. The raw materials for the process were Phosphoric Acid and finely ground phosphate rock. These items were mixed manually in a huge concrete area. The assignment was to develop a continuous process.
In the pilot plant our prototype employed a “pug mixer.” This was a trough-type device in which the acid and powdered rock were mixed by paddle-type Stellite TM blades (this extra-hard material was used due to the acidity and abrasiveness of the reagents). The problem was that as time went on the reacted slurry would harden into a concrete-like mass and cement itself to the walls of the mixer, of course stalling out the motor drive. At best, we could only get one or two hours of production.
One day while mulling over this problem, “nature” called. After I was done, I flushed the commode and was astonished when I realized how clever this device really was. It could, technically speaking, take various quantities of liquids and solids, yet still clear the bowl. I thought that this might be the solution to our dilemma. I sketched up my idea and took it to the Chief Draftsman to have him put together an accurate blueprint. Since it was near the beginning of April, he started laughing, thinking this “geek engineer” was constructing a rather elaborate “April’s Fool’s” joke. It took some time to convince him that I was serious.
After we had a scale drawing, I took it to the lead fabricating Shop Foreman who (luckily for me) was a friend of mine. Again, it took some convincing, but he agreed to put it together. What we had created was a 3 foot-high conical bowl, where acid was injected horizontally at the rim and spiraled down to the 3-inch diameter outlet at the bottom. A belt feeder fed the fine phosphate rock down into the center of the cone. The rock/acid slurry then flowed out of the bottom of the bowl onto a 45-degree belt conveyer, where it set up into a foamy solid cake for further granulation.
I had informed my boss that I had come up with a solution to our problem and, much to my chagrin, discovered that he wanted me to brief the company “bigwigs” at 10AM the next day. I talked to my buddy, the shop foreman, and he managed to find a few guys that were willing to help (I’m not sure, but it MAY have cost me drinks and steak dinners).
After the day shift went home, we got to work. We installed the whole system and got it working by 6AM. Since I had them fabricate the test unit out of lead, it made it easy to make several modifications. Namely, I had to put a donut ring top on the cone to keep the acid from swirling up and out, and I also had to add four little baffles at the throat to enhance complete mixing. With these changes, the unit ran continuously all night. I went home, showered/shaved, and was back at work by 8AM. I put together a few charts and got ready for my 10:00 meeting.
When I began my description of the system, I could see that no one believed that I was serious. After many interruptions, complaints, threats of unemployment, etc., I finished my briefing with, “Well I don’t know what the problem is, it’s been working since 6:00 this Morning!!!” In retrospect, I can’t say what the managers and MY boss thought of my engineering prowess, but ever after I was honored, in a manner of speaking, as the inventor of “Charlie’s Toilet Bowl.”
Charles R. Picek, PE (retired), graduated from Johns Hopkins University with a BE in Chemical Engineering. His 50+ year career includes involvement in the Petrochemical, Fertilizer, Pharmaceutical and Environmental industries. He holds several recent patents on filters and processes for his groundbreaking work in Water Purification and in situ Serum Sterilization. He has also served as Vice President of Engineering AMF, Cuno Division, Sales Development for the Pall Corporation, and President of the consulting group of CRP Associates. He is currently enjoying retirement in Florida, including his first loves: Boating and Fishing.”His story was told to and ghost written by his nephew Dwight Bues, Systems Engineer.