15.29 Remediating spent BHO extraction material for residual solvent

In answering process questions via email or at other forums, one cropped up that I thought I might share.  That was how do you process spent plant material from the BHO extraction process to below Lower Explosive Limits so it can be removed from the C1D1 extraction booth?

I will share how I did it and open the discussion for others to share processes that have worked out for them.

I started by designing my extraction system so that I could recover the column and collection tank either collectively or separately. 

After extraction I recovered them together until I reached -15” Hg, at which time I isolated them and recovered them discretely, albeit attached to the same vacuum manifold and recovery pump.

I then circulated 150F hot water through the column jacket and recovered the column to -22” before switching from the recovery pump to the high vacuum pump.

I continued to heat and vacuum the column until we reached -29.5” Hg/10,668 microns, at which time I backfilled with N2, and then pumped it back down to -29.5” Hg again, before backfilling with N2 a second time.

When opened to atmosphere, the spent material measured less than 10% LEL.

-29.5” Hg is about .42” Hg remaining atmosphere or about 10,668 microns.  There are 760K microns to an atmosphere, so the first backfill the remaining atmosphere represents 0.014 or 1.4% of remaining atmosphere, which dilutes the incoming N2.

The second time, the remaining 10,668 microns at 1.4% concentration was diluted with 749,332 microns of N2, resulting in 760,000 microns with a concentration of 1.97 X 10-4, or 0.00197%.


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