After thinking about this glycerol prewash stuff for some time, I finally tried it for myself.

It made sense to me that the glycerol from the previous batch is up to 40% methanol and has residual lye and possibly some attraction for water to help as a drying agent. So, at the worst it wouldn't hurt...

I used my small reactor...approximately, 60L. The only changes I made to the generally accepted "standard" process was that after charging my 60L processor with 50L of WVO, I added the previous batch by-product to the WVO. After heating to 130F and mixing for 90 minutes, I let it settle for about 6 hours. This was a little bit lengthy as the glycerol doesn't seperate from the WVO as quickly as Bio ...I guess because the difference in density isn't as great. Then titrate and process as normal...with one other change...I only used 17% methanol instead of my usual 22%.

The batch seemed to process fine and I performed the 3/27 test ...passed with flying colors!!!

I am still not sure about everything so I will do this again with caution over the next several batches. I'll pay more attention to volumes of oil and byproduct to see if I get an apparent increase of WVO after the initial byproduct wash that others have claimed...if so, maybe this is methanol that came out of byproduct and stayed in the WVO ...which justifies the lower % methanol for methoxide step. ...and reclaims some methanol from glycerol byproduct without using much additional energy or effort.

I'm still convincing myself this works, but, my first attempt at it seemed to work extremely well. ...if someone out there has had a negative experience doing this ...please let me know.

Regards to all!

Rich,

quote:

I only used 17% methanol instead of my usual 22%.

The batch seemed to process fine and I performed the 3/27 test ...passed with flying colors!!!

Great news!

Couple of questions...

Have you previously tested to see how low you can go with methanol and still pass 3/27?

Do you control the temp. of your 3/27 test and if so, what was the temp. of the test?

How much did your titration improve?

How long do you run the processor, what temp., and what pump is used for mixing?

Thanks for sharing your results.

OK, I have a question. Once in a while, I get some higher tritrating oil.(5-7 range NaOH). My glycerol hardens overnight. What can I use to keep this in liquid state or how can I heat it up enough to use it in a prewash? I use an water heater for a reactor so it is sealed to where I just can't dump it in the top and heat it.

quote:

Originally posted by holeshotkid:
OK, I have a question. Once in a while, I get some higher tritrating oil.(5-7 range NaOH). My glycerol hardens overnight. What can I use to keep this in liquid state or how can I heat it up enough to use it in a prewash? I use an water heater for a reactor so it is sealed to where I just can't dump it in the top and heat it.

You will have to switch catalyst to KOH.
Rick H...

I just tested my second source of WVO with the test kit I purchased. It stayed purple after adding 5 mL, which the instructions says that this should titrate below 2.5 g/L KOH. So, qustion is, if this oil titrates this low, is it worth doing a Glycerin pre-wash?

Would the NaOH work if I started the next batch of oil before the glycerol hardened? Sorry if this is a stupid question but will it still lower tritration?

Andrew, I have not previously tested how low I could go on Methanol concentration. I've always used 20-22%. About 12% is all that is actually consumed in the reaction. The rest is just excess methanol as a catayst to drive the reaction further to the right. I'm guessing that the minimum amount needed to get a complete reaction will vary somewhat with the quality of the oil. I do, however, pay extreme attention to getting my titrations accurate and put the correct amount of NaOH in the processor.

It's been 24 hours and the 27/3 test-tube is still crystal clear...no fallout of unreacted oil and not a single white fluffy crystal. The tempe of the test is room temp...about 73-75 F in my basement. The BD that I took from the processor was a bit warm though...probably almost 90 F.

I did not check titration before I added the glycerol byproduct so I don't know how much or even if the titration improved at all. My biggest goal was to pass some of the methanol in the byproduct to the WVO to cut down on methanol use without going through the trouble of recovering the methanol first. Any other benefit is just "bonus".

I use a HF 1" Clearwater Pump ...cheap. Keep in mind that my reactor is relatively small ...16 gal (60 L). I am using two HF pumps on the bigger reactor and expect similar reasults.

The process I used was similar to what I've read on here before so the credit goes to somebody else...but my process was basically as follows:

1) add 13.5 gal (about 51 L) WVO to processor
2) Turn on pump and heater to start circulating
3) add byproduct from previous batch. approx 2 gal (7.2 L)
4) Let mix and heat to 130 F for a total of 2 hours
5) Shut off heater. Wait a minute to let circultating fluid cool element, then shut off pump.
6) Let settle for 4-6 hours and drain byproduct. This took a little longer because I wasn't sure what I was looking for...byproduct is dark and WVO was dark. Also settling is longer because contrast in density between byproduct and WVO is closer to eachother than the contrast between byproduct and biodeisel. I didn't pay close enough attention to volumes to confirm if less byproduct came out than went in...seems like if some methanol transferred then you can lose some volume of byproduct.
7) Turn pump back on. Turn heater back on (setpoint still 130 F).
8) Titrate
9) Mix methanol and NaOH and let dissolve while processor reaches temp again. I do allow the NaOH to completely dissolve before adding it to batch. It might be a little cloudy but no crystal are in methanol tank when I decide to add and it is cool ...stops generating heat from the reaction between methanol and lye because reaction is finished.
10) Shut heater off (Pump still running)
11) Add methoxide through 1/4" ball valve on suction side of pump over a 20 minute period (or longer). I control the valves to have a very slow addition to allow methoxide & WVO to get thoroughly mixed by pump impellor.
12) After mixing is complete, I turn the heat back on to maintain 130 F. CAUTION HERE...I have a proportional temperature controller that cycles the heater on and off to maintain temperature. If your heater is controlled manually then I would not recommend turning the heater back on. The methanol can boil when coming in contact with the heater and cause an explosion danger. If you do not have a temp controller on your unit then I would highly recommend insullation and longer mixing time.
13) mix for 90-120 minutes.
14) Shut off heater and let circulate for a minute or two then turn off pump.
15) Let settle for at least 90 minutes...2-3 hours is better.
16) Drain byproduct
17) At this point, I transfer to an open-top 55 gal drum and mist wash for 3 hours. Shut off mist and let settle until it clears. I've had it clear in as fast as overnight...sometimes it takes a few days. If, after 2 days it didn't clear then I may wash some more or put in the processor for heating and air injection to dry...but, it seems everyone has their favorite flavor of finishing techniques.

If the BD clears fast, I usually siphon off the top 3/4 of the volume, passing it through a standard fuel filter and pour it directly into my vehicle. I've had no problems with this finishing method so far. I've been making BD for about 6 months.

I ran a 87 MB 300SDL for 5 of the 6 months and now I have a 2000 Ford Excursion 7.3L PSD. No modifications to either vehicle had been done.


HoleShotKid...now that outside temperatures for me have been above 60 F duing the day, I have not had my byproduct get that hard. I've also noticed that there is a tendancy for byproduct to harden if you don't get all the water out of your WVO...it has been obvious to me when more soap is present and I attribute that to excess water.

Also, I should say that I screen and then strain my WVO through sheer curtain material (1$ yard at Walmart) before processing. My thinking is that water saturates the breading and other contamination in the oil. If you get most of the suspended food particles out of your WVO then you conquer the water problem.

It's working for me.

Sounds good, thanks. I haven't had any problems yet but was looking to conserve some catalist on higher tritrating oil.

Rich,

quote:

I use a HF 1" Clearwater Pump ...cheap. Keep in mind that my reactor is relatively small ...16 gal (60 L). I am using two HF pumps on the bigger reactor and expect similar reasults.

Here is where I was going with my questioning:

If you are running 16 gallon batches 2 hrs with that pump, you may well be able to pass with 17-18% already without the pretreatment. Without some before and after testing, the result is good, but we can't really tell how much it might have improved things.

quote:

Originally posted by irokcj5:
I just tested my second source of WVO with the test kit I purchased. It stayed purple after adding 5 mL, which the instructions says that this should titrate below 2.5 g/L KOH. So, qustion is, if this oil titrates this low, is it worth doing a Glycerin pre-wash?

I wouldnt bother for low titrating oil - its more time and work for marginal benefit. If it titrated at 3.5 and higher KOH I'd say yes, definitely.

quote:

Originally posted by holeshotkid:
Would the NaOH work if I started the next batch of oil before the glycerol hardened? Sorry if this is a stupid question but will it still lower tritration?

Sure, I wouldnt like to have to melt old byproduct, with methanol fumes, cost of heating, as well as the extra messing about. In fact if you got the byproduct into the next batch of oil while its still hot that would be even better, as it would react with the FFAs quicker and add some 'free' heat to the oil.

If I can get some benefit of extracting methanol that effectively lowers my standard for the recipe then I would glycerol wash all the time. I don't care what the titration is before the wash as it is after the wash that matters. Although I fully understand that I have no data to suggest that any benefit is gained on all WVO without titrating before and after. What has me very interested is the 27/3 test result from this batch.

Every single batch that I used the 27/3 test on before this produced either, some unreacted oil (incomplete reaction) or some cloudy fluffy crystals that suggested I'm on the verge of a complete reaction. This is the first 27/3 test that yielded a perfect result for me. I've never had any trouble from using any batch I've made and I am striving to make the best batch within reason. The byproduct wash seems to be little additional trouble if I can have consistently perfect results on the 27/3 test.

For the purpose of gathering some additional data...I will titrate a few batches before and after just to satisfy my own curiosity and everyone elses.

Again, I am hoping that some of the 30-40% methanol content transfers to the WVO to assist in my reaction. Many of us are not recovering methanol from the byproduct. I have intentions of doing so but haven't put together the appropriate system for recovery yet. In the mean time, if I can get some benefit from all this stuff laying around then so be it.

HoleShot...

I will say that I have had different behavior from the byproduct of my NaOH base reaction depending the WVO source. A few of mine did become lumpy and gel-like. But the sources I'm using now are exclusively Canola Oil. I do not have solid byproduct on a normal day above 60F with the oil I am using and my process is based on NaOH.

Andrew,

I will try processing some a bit lower in Meth concentration to see where the break-point is. With Meth being the most expensive part of this process, seems to me worth the effort. Thanks for your reply.

Rich,

I processessed a batch yesterday afternoon and drained most of the glycerol off last night. I got up this morning to go to work and there was ice on the winshield... Tomorrow it's going to hit 70 and hi 80's by mid week. Damn Kansas weather. My last batch tritrated at 6.7 and turned out great. Hopefully my glycerol doesn't harden once it gets warmer out. I was just out of oil this time so I went ahead and left the glycerol set in gallon jugs. I'm looking forward to trying this but unless my next tritration is off the scale (+7 or 8), I will wait to try this in warmer weather. Any way I can save on NaOH or Methanol is a bonus. BTW, excellent post on your stages of making bio. Thanks for sharing the info.

Troy

quote:

I wouldnt bother for low titrating oil - its more time and work for marginal benefit. If it titrated at 3.5 and higher KOH I'd say yes, definitely.

Jehu, but exchanging methanol and catalyst are only 2 of the 3 benefits. This process really seems to dry the oil, thereby making the washing process much easier. I do it regardless of the titration nowadays. - Steve

quote:

quote:
Originally posted by holeshotkid:
OK, I have a question. Once in a while, I get some higher tritrating oil.(5-7 range NaOH). My glycerol hardens overnight. What can I use to keep this in liquid state or how can I heat it up enough to use it in a prewash? I use an water heater for a reactor so it is sealed to where I just can't dump it in the top and heat it.


You will have to switch catalyst to KOH.

I use the NaOH and I also had a couple of near misses with plugging up my lines, valves, and pump. Now I do a 5% prewash with water at the end of my process cycle. The glycerin now remains very fluid and is easy to drain off. But, since water was introduced to achieve this, will it affect the glycerin prewash method??? If it does hamper this method, then going to the KOH seems to be the answer.

Jim...

quote:

But, since water was introduced to achieve this, will it affect the glycerin prewash method???

I started a controlled experiment over the weekend to test exactly this. I ran out of time before I quite completed it, but I plan to finish it when I get home tonight.

Basically I'm testing if the ability of glycerin to hold water is so much greater than that of WVO that only an insignificant amount of water will transfer to the WVO, even with glycerin from a 5% prewash.

I created a controlled 5% prewash glycerin with a known volume of water and methanol in a demethed and dewatered glycerin sample. Then mixed and allowed to separate. I still need to make the volume measurements of the two separated parts and measurements of the WVO to determine methanol and water present in the WVO following the FP1 treatment (glycerin pretreatment).

quote:

Originally posted by AwesomeNet:

quote:

I wouldnt bother for low titrating oil - its more time and work for marginal benefit. If it titrated at 3.5 and higher KOH I'd say yes, definitely.

Jehu, but exchanging methanol and catalyst are only 2 of the 3 benefits. This process really seems to dry the oil, thereby making the washing process much easier. I do it regardless of the titration nowadays. - Steve

Hi Steve - thats fair enough. I usually get good dry oil anyway so I didnt think about the glycerol drying. I do get wet oil from time to time so in that case I'll try out the glycerol pretreatment.

quote:

Originally posted by Ryan P.:

quote:

But, since water was introduced to achieve this, will it affect the glycerin prewash method???

I started a controlled experiment over the weekend to test exactly this. I ran out of time before I quite completed it, but I plan to finish it when I get home tonight.

Basically I'm testing if the ability of glycerin to hold water is so much greater than that of WVO that only an insignificant amount of water will transfer to the WVO, even with glycerin from a 5% prewash.

I created a controlled 5% prewash glycerin with a known volume of water and methanol in a demethed and dewatered glycerin sample. Then mixed and allowed to separate. I still need to make the volume measurements of the two separated parts and measurements of the WVO to determine methanol and water present in the WVO following the FP1 treatment (glycerin pretreatment).

Any results? Interesting read, thanks for posting. KD