WFU Biofuels

Wake Forest students, faculty, staff and associates making and testing vegetable-oil based fuels.

Saturday, December 09, 2006

Big reactor, big reactions

You have to break a few eggs to make an omelet.

I emailed The Shaman this morning to see if he wanted to try and get the big reactor fired up. He emailed me back and said "no", but I was already on my way out to his place. Nice as he is, he didn't say anything when I showed up at his door unannounced and we spent the afternoon learning some good lessons on large-scale biodiesel production.

Lesson #1. Be careful with strong bases. That burning taste in your mouth when you are watching someone measure out KOH, even in a well ventilated room? It's KOH. There is a large fraction of fine powder in granular bases, and if you shine a strong light behind the "rocks" of KOH while you are handling it, you'll see it floating up in the room. Wear a mask. And gloves. And goggles.

Lesson #2. If you see a weak link, potential problem, or something that might break in a system, fix it or change it before doing anything else. Some cheap plastic fittings snapped today and yesterday. The first two times just resulted in mild anger. The third time it resulted in someone getting sprayed with a pressurized methanol/KOH mixture. This person was out of their pants before the methanol got through the cotton, but it was a big eye-opener. Friends, when you're working with 10s and 100s of gallons rather than milliliters and liters, the pressures change, and failures that are minor inconveniences in an appleseed can become big problems.

Lesson #3. Think bad thoughts. When we got the methoxide mix into the big reaction tank, we heard a foomf. Very exciting. Luckily, we had gone thorough a dry run and long walk through of bad situations and what we would do to shut things down and get out of the reaction room safely. And quickly.

Which we did.

It turns out that the methanol was vaporizing fast enough to exceed the capacity of our pressure relief hose. This caused the top of the tank to pop up and hit some of the boards. Not too dangerous, but eye-opening. In general thinking about how to stop leaks, channel spills, and general plotting gloomy scenarios can pay off if things hit the fan, which they did a couple of times in getting this running.

Lesson #4. Make sure there is a dedicated pressure relief valve in every system. Breaking one of the cheapo pump fittings and loosing some methanol just might have saved us from learning this lesson the hard way. We were going to pump from the methoxide mixer (located outside the reactor room) into the tote through an inlet fitting that would have inadverntantly resulted in there being no pressure relief on either system. Now, I'm no chemist, but I'm thinking that boiling 12 gallons of methanol in a closed system that isn't built to take pressure could have ended-up badly. Check for pressure relief. Unscrew something, put an open hose barb in, or buy a cheap pressure relief valve and put it some place where goo can't clog it.

Now, the good news about all of this is that over the past two days we figured out how to use the blademaster to move thick oil when it is cold, heat it, dry it with magnasol, filter it, mix a big batch of methoxide, and react it, and do it safely. This last part because we broke everything that was weak or unsafe.

So, we're ready for big batches. There are some more tricks that we learned that I'll post in the coming days. Despite the snafus, the reactor and methoxide system is awesome, especially the heater and dual pump system. With another take-off valve at its highest point we can use that system to dry oil, separate glycerine--just about anything!

I'll close by voting that we change the Shaman's nickname to Chuck Yeager.