SUBcritical or SUPERcritical extraction? That is the question.
We have recently been told that we can’t possibly extract one ton of material per day because it takes “forever” to winterize and that is why, “no one runs supercritical CO2 anymore.” People just winterize using their extraction machine these days.
Well, we certainly don’t have anything against running low pressure and low temperature methods on our machine to accomplish this goal. By doing so, however, you also will experience a considerable increase in run time to obtain satisfactory recovery with concomitant precipitous reduction in overall throughput.
So there is a significant trade-off on throughput. Some have pointed out that winterization time is lengthly (at 10-20 hours), so the actual throughput to winterized media is the sum of: run time + collection time + winterization time + solvent removal time. However, no serious operation actually operates serially in that way, rather, they use First In First Out (FIFO) lanes so that the cycle time for these longer processes is zero.
The FIFO lane procedure for winterization amounts to this:
“When you put a bucket of oil to be winterized in the freezer, take one bucket of winterized oil out of the freezer. This takes about 30 seconds and effectively reduces the winterization cycle time from 10-20 hrs to 30 seconds.”
FIFO lanes are ubiquitous in well-run operations as they are used to join disparate processes with differing cycle times. To learn more about FIFO lanes, and their essential use in lean manufacturing, check out this resource from The Lean Institute, click here.
And now, back to the question of throughput.
|Extraction Method||Low Pressure, Low Temperature (a)||High Pressure, High Temperature (b)|
|Extraction runs in 10 hours||2||10|
|Yield ( 15% material/kg)||2||13.6|
|Throughput to Crude Oil (g/hr)||200||1360|
|Time for Winterization (hour) at -20°C||Using FIFO, cycle time is less than 1 minute (c)|
|Filtration time (hr)||0.2 (d)||0.5|
|Winterized Oil Yield (%)||85%||70%|
|Total Yield (kg)||1.7||9.52|
|Throughput to Winterized (g/hr)||167||907|
|Solvent Removal||Using FIFO, cycle time is 10 minutes (c)|
|Throughput to Wilterized oil (g/hr)||167||907|
|a. Run time with high flow pump is approximately 4 hours for 90% efficiency.|
|b. Run time with high flow pump is approximately 1 hours for 99% efficiency.|
|c. Using First In First Out lanes, winterization time is the time it takes to put a bucket into the freezer, and take a winterized bucket out (30 seconds).|
|d. Dewaxing of oil from low pressure/low temperature runs is sometimes required anyway.|