This is my third batch using acid process. The first two times, I mixed for 12 hours and titration dropped from 11 down to 3.5 . I use an appleseed with a harbor freight pump. Does anyone let their pump run overnight unattended ? I usually do this on weekends and check on it every 2-3 hours. Can I trust these cheap little pumps overnight ?

Thanks

Hello biohusker

The blue harbor freight pump has been reported to have caught fire on several ocassions.

Hi biohusker,

I have been using these on the HF and NT pumps since they do not come with overload protection.
They work well, are not expensive and easier than fuses. They also come up to 40 amps and I have used them in controls for heater breakers as well.
http://www.grainger.com/Grainger/items/4VA62

Good Luck,
Tony

quote:

Does anyone let their pump run overnight unattended ? I usually do this on weekends and check on it every 2-3 hours. Can I trust these cheap little pumps overnight ?

I have 1 HF pump that recirculates my biodiesel to filter out soap...I let it run all day sometimes, but still don't feel comfortable letting it run overnight (even though that is less time than all day).

One compromise I have done when doing an acid stage that I want ready to go the next morning is to put the HF pump on a 24hr timer. Set the timer to run for 2hrs, then off for 2hrs, on 2, off 2, etc all night long. I did this and it seemed to have no negative effect of the final titration following an acid stage, but the pump only ran for half as much time, so I figured it had adequate cooling in between periods of activity...and that made me more comfortable.

Just make sure you choose a good timer that can handle the amps of the pump (I think its like 8-12amps), and not just a cheap Christmas light or lamp timer than is only 5 amps.

The papers I've read and my own limited experience with acid-base suggest that almost all the esterification is complete (as far as it's going to go), in
about 5 hours. I know many of you run it much longer than that, and see the titration continue to fall the whole time.

I'm wondering if you could get the time down to 5 hours or so, with higher temps, a different type of agitation, dryer ingredients, or more H2SO4....

A mix of my opinion and limited experience;

quote:

I'm wondering if you could get the time down to 5 hours or so, with higher temps,

Probably, just keep it below 165F to prevent the methanol from boiling (145F is BP for pure methanol, it solution of oil it has been found to be up to 175F or so)

quote:

a different type of agitation,

YES! 24hrs were necessary for my HF pump to have the effect of dropping to 3-4ml range that the acid stage limits out at. 1" plumbing and a larger pump (commonly called a PitBull) did the same in 8hrs...with the 2-on, 2-off procedure.

quote:

dryer ingredients,

Probably...water hurts everywhere else in BD processing, so it likely hurts here too.

quote:

or more H2SO4....

Yes, but the finish point will be higher. If you use 1ml/L, the final titration is supposed to be about 2-2.5ml NaOH...but I would suspect mixing time will be long. With 2ml/L, its more like 3-4ml NaOH at the end. It probably goes up in some sort of linear fashion. I know the one time I screwed up and added 20ml acid/L (decimal point error), my final titration was 7ml KOH, if I remember right...starting from 13-14ml KOH. It did drop pretty fast and then just stayed there...and I realized my mistake.

the acid/base doesn't reach an endpoint. but a point of diminishing returns. I've done runs as long s 3 days and the titration continued to drop. after about 12hrs it was a very slow change per hour.

too much temp the methanol boils out.
too much acid the ending titration is higher than the lowest possible.

the higher the titration the longer the processing time.

there are places that sell thermal fuses. one could be wire in series with the power to the pump and touching the motor housing.

-dkenny

quote:

Originally posted by dkenny:
the acid/base doesn't reach an endpoint. but a point of diminishing returns. I've done runs as long s 3 days and the titration continued to drop. after about 12hrs it was a very slow change per hour.

too much temp the methanol boils out.
too much acid the ending titration is higher than the lowest possible.

the higher the titration the longer the processing time.

there are places that sell thermal fuses. one could be wire in series with the power to the pump and touching the motor housing.

-dkenny

We have used both the harbour freight and the northern tool pumps for countless hours. We currently use the northern tool pump for the increased flow rate. The pumps run continously for 72-96 hours during water removal, followed by reaction. Our pumps typically wear out due to bearing failure after about 2 months. We have also had pump failure due to broken vanes in the pump from crud cooking to our heating element and eventually falling off to get cycled through the pump.

We process between 2 and 3 batches a week starting at 275 gallons of oil (one tote) per batch. We have been processing on this schedule since last April with a slow down in the winter since we operate outdoors. We acid esterfied every batch, primarily because we process anywhere from 30-70% chicken fat in each batch. The chicken fat titrates anywhere between 7ml - 15ml depending on how long it sits.

We used to mix for 12 hours using 1.5ml/L of H2S04 per litre of oil. We have plotted the progress of the titration on several occasions in order to hone in our process.

In our experience we have seen the titration hit the low point of 0.6-1.4ml after about 3 hours of recirculation using a northern tool pump at 12gpm. After 3 hours the titration actually starts going back up with a plateau at around 2.3-2.6ml.

If you let the oil settle for long periods of time you will actually see the titration drop again. I've always wondered if this was due to the residual water settling out and allowing the reaction to go a little further.

We remove all the water before processing by heating to 235F, cooling to 145F, adding 1L of technical grade H2S04 and inducting 35 gal of methanol over the course of 1 hour.

Once we obtain a target titration of 1.4ml (<1% FFA) we follow up with a base stage using about 6.4kg NaOH in the remaining 20 gal of methanol left in the 55gal drum it came in. We induct the 20+gal of methoxide from the drum over the course of 2 hours while actively heating. We continue heating during and after methoxide induction until we reach 150F at which point the heater is turned off.

We typically monitor the reaction through vessel pressure. Even without heating the reaction continues to gain heat and expand pushing air out of the tank. We the reaction hits equilibrium the pressure subsides and then turns to a vacuum indicating the reaction is over.

At this point we electrostatic settle the glycerol and then drain the biodiesel from the reactor via in reactor stand-pipe and pump out the glycerol last.

Has worked well for us for quite some time.

--
Jeff Brandt
Sun Break Biofuels, LLC
http://www.sunbreakbiofuels.com
mailto:jeffb@sunbreakbiofuels.com

Hi Jeff,

Glad to see you back in the mix. I liked the resin towers. How long did it take to get rebuilt and back to making bio?

Jeff,

Thanks for the detailed description of your process.

Interesting that you notice the change in pressure. Have you done testing to see how much the reaction will continue after the point where the pressure changes?

About the pumps...

quote:

We currently use the northern tool pump for the increased flow rate.

At least on the test I did with room temp. oil, the two pumps, (HF and NT) are EXACTLY the same in terms of flow rate. I like the NT better anyway.