http://www.biodieselmagazine.com/articles/166451/kelley-green-biofuel-showcases-biodiesel-ingenuity-at-cbc-event
Kelley Green Biofuel showcases biodiesel ingenuity at CBC event
By Ron Kotrba | August 27, 2014
Small-scale biodiesel producers have long been a source of process
innovation and ingenuity, and the minds behind Kelley Green Biofuel
simply confirm this assertion. Kristopher Kelley and Link Shumaker
presented Kelley Green Biofuel’s approach to biodiesel production and
methanol recovery at the 2014 Collective Biodiesel Conference this month
in Pittsboro, N.C.
Kelley Green Biofuel is an RFS2-registered small-scale facility based in
Kentucky that can produce 70,000 to 100,000 gallons of biodiesel per
year. The farm-based plant uses repurposed propane and milk tanks to
make biodiesel. While the milk tanks were designed for cooling with
Freon, they were plumbed with steam to heat rather than cool, which
“works just fine,” Kelley said.
The process heat and steam come from an Ag Solutions low-pressure steam
boiler that has been tweaked to burn what Kelley and Shumaker call
“g.esters”—or a mixed stream of glycerin and high-FFA out-of-spec fuel
from the glycerin bottoms. A 15-gallon-per-minute (gpm) Alfa Laval
centrifuge is used to save residence time in the soap-settling tank,
which also allows water-free washing with resin columns and moves
batch-processing further along in less time. A positive displacement
meter is used to measure yield, for RIN recording.
Kelley Green performs the 27/3 test for glycerin and uses Eurofins QTA
on demand program for other testing parameters. What’s lacking at this
point for testing, they said, is an in-process test for total glycerin.
The process features vapor recovery to keep methanol vapors down with a
venting system connected to any tank in which the volatile alcohol is
introduced. They ground and bond across metal components when using
plastic because plastic could build up a static charge, and use an
explosion-proof motor on the variable frequency drive.
Biodiesel exits the reactor containing about 4 to 6 percent methanol by
volume, and enters a flash drum pulling 27 to 28 inches of mercury.
Using steam the mixture temperature is raised to about 185 F, requiring
about 42,000 Btu. A 5.5 gpm shell-and-tube heat exchanger is used. About
365 gallons of methanol-laden (4-6 percent) fuel is sent into the flash
drum and through the methanol recovery system they reclaim about 13
gallons of methanol with 2 to 3 percent moisture. When choosing a pump
for a methanol recovery system, they recommended one with a net positive
suction head.
Kelley and Shumaker said developing a safe and reliable methanol
recovery system proved much more complicated than developing the
biodiesel reaction process.
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