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Acid Step Discharge: Pictures
Hello everyone. Thanks for all your great contributions and insights on biodiesel production.

I write from Central America. We are producing biodiesel from WVO. We can only get our hands on WVO that titrates at 13ml or above, so we decided to use the Acid/Base process. Still trying to get our hands and heads around all the details of the process. We have already produced biodiesel that passes the 3/27 test, either on a single process or by reprocessing. But we are still rough around the edges in terms of efficiency and yield.

Right now we are a little puzzled by the discharge from the acid step. We used the following recipe:

*35 gallons (133 liters) of WVO
*Titration of 15ml with KOH solution
*4.2 gallons of methanol
*320ml of sulphuric acid
*Temp of 130F

We added the methanol/acid mixture to the heated WVO and mixed for about two hours. Then we let it settle overnight. By next morning the titration had dropped to 8ml. (In other batches titration has dropped to 6ml or even 4ml.) We took out about 7.5 liters of liquid from the bottom (discharge) and continued on to the KOH step, replacing the 7.5 liters of discharge with additional methanol. We let the discharge settle and we obtained what you can see in the picture. We do not know how to explain the layers of the discharge.

We collected the discharge in three 2.5-liter bottles. The order of collection is from left to right. So there are 4 distict layers in the discharge: (1) white creamy stuff, (2) a reddish brown watery stuff, (3) a light brown buttery stuff, and (4) a dark brown/black liquid.

Can someone explain what the layers are? Is it normal? Can any conclusion be drawn from the layers? What would have happened to our batch had we decided not to remove those 7.5 liters of discharge?


Imageliquidodeprocesoacido.JPG (45 Kb, 159 downloads) Discharge from Acid Step
Registered: June 20, 2008Reply With QuoteReport This Post
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Just looked at you pics, and the best I can tell, in order from left to right:
first bottle, soapy water with gly over it. \
2nd, watery gly with oil over it,
3rd bottle, more gly with oil over it.
Thats the best I can tell from the pics. Was the oil dry before you started processing the acid stage?
Registered: May 13, 2008Reply With QuoteReport This Post
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Creo que tu principal problema es que estás realizando el proceso básico con tritación mayor a tres. Mi experiencia me ha demostrado que si no logras bajarla 3 o menos tendrás mucho jabón ( mayor del que obtienes con 3 o menos)y menos obtención de biodiesel. Por otro lado creo que no te baja más porque estás utilizando mayor cantidad del ácido del necesario.Veamos:Yo empecé a utilizar la formulación que el sr. Van Gerpen informa de valor ácido x % de acidez correspondiente x cada 100 libras de aceite. en otras palabras:
Si tu tritación dió 15 ml utilizando KOH equivale a la mitad en % de acidez, o sea, 7.5%, multiplicamos ésto por 0.05 = 0.375 x 35 gls pesan ( 7.5 lbs)= 262.50 lbs., como el cálculo espor cada 100 lbs tenemos x 2.625 todo igual a: 0.05 x 7.5 x 2.625 = 0.984375 lbs.. Si lo llevamos a klgs. que en lo que acostumbro a trabajar , tenemos 0.984375/2.2046 = 0.44509 kgs y si lo llevamos a gramos tennemos 445.50 grs.. Con éstos valores en gramos no sé a cuanto equivale en mls. ( el ácido sulfúrico pesa mucho). Pero seguro que más de lo que tu ha estado usando. En mi experiencia logré algunas veces bajar el valor ácido a 3 ó 4 , pero la mayorLa de las veces estuvo por emcima de 4 o en muchos casos igual al valor ácido inicial. Siempre ,,e pregunté por qué.
Logré la respuesta con la experiencia de DKenny , la cual me parece tú estás utilzando, él usa mucho menos ácido y después de utilizar sus consejos he logrado llevar el valo ácisdo siempre a 3 , partiendo de 9 ( con valoración NaOH no Koh, En porciento significan lo mismo, pero la tritación no signmifica lo mismo , lo que usando KOH el % ácido es la mitad , no es lo mismo usando NaOH). Si te interesa luego puedo decirte un estudio muy claro donde puedes ver lo que te digo y una tabla para su uso.
DKenny utiliza lo siguiente: valor ácido x 0.2 x litros de aceite usados. En tu caso con 15 mls (DKenny también utiliza KOH): el resta el número de tritación al que tú quieres llevar la reacción, pero por experiencia generalmente no baja de 3, por eso el utiliza 3.

Vuelvo, (15-3) x 0.2 x 133 =319.20 mls. que es lo que tú dices estar utilizando. Lo de Van gwerpen es porque como lo respeto mucho , decidí por mi cuenta utilizar la cantidad que a él le da en gramos como si fueran mls.( con la única finalidad de no utilizar la alta cantidad de Van Gerpen ni la menor cantidad de DKenny ) y quiero decirte que realmente todas me han bajado a 3 , siempre que no esté por encima de 9 ( con NaOH, ésto equivale a 12.88 con KOH ), más de ahí es necesario hacer una segunda reacción. Si tienes que sacar el metanol , agua del tope, pero sólo cuando la tritación inicial sea mayor a 7.La cantidad a sacar cuando lo necesite será igual a la mitad del metanol utilizado en la reacción.
En fín,. creo que la cantidad utilizada de ácido fue mayor a la necesitada pues sólo así se va al fondo y no arriba.Como ves te he hecho una mezcla d muchas cosas para ver si se te prende un bombillito.
Mar Caribe
Registered: August 10, 2008Reply With QuoteReport This Post
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Wow I wished I understood spanish. This guy seems to know what he is talking about.
Location: Northern Ontario, Canada | Registered: April 03, 2007Reply With QuoteReport This Post
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Here is the translation thanks to Google translator:

I think your biggest problem is that you're doing the basic process with tritación greater than three. My experience has shown me that if we do not get 3 or lower it will have much less soap (bigger than you get with 3 or less) and less obtaining biodiesel. On the other hand I do not think you're using low because most of the greater amount of acid necesario.Veamos: I started to use the wording that the sr. Van Gerpen valuables reportedly acid x x% of acidity for every 100 pounds of oil. in other words:
If your tritación gave 15 ml using KOH is equivalent to half in% of acidity, or 7.5%, multiply it by 0.05 = 0,375 x 35 gls weight (7.5 lbs) = 262.50 lbs., As the calculation we Spore 100 lbs x equals the entire 2625: 0.05 x 7.5 x 2625 = 0.984375 lbs .. If what we klgs. that what we usually work, we 0.984375/2.2046 = 0.44509 kgs and if we Tenno grams 445.50 grams .. With these values in grams do not know to what is in mls. (Sulfuric acid weighs a lot). But surely most of what you have been using. In my experience sometimes managed to lower the acid value of 3 or 4, but the majority of the time he was 4-for emcima or in many cases equal to the initial acid. Always, and I asked why.
I managed to reply with the experience of DKenny, which I think you're use it, he uses much less acid and then use his advice I have managed to bring the values ácisdo always to 3, from 9 (with no valuation NaOH Koh, in percent mean the same thing, but the tritación not signmifica the same, so using the KOH% acid is half, is not the same thing using NaOH). If you are interested in, then I can tell you a very clear where you can see what I say and a table for use.
DKenny used as follows: acid value x 0.2 x liters of used oil. In your case with 15 mls (DKenny also uses KOH): the subtracts the number tritación of you want to keep the reaction, but not generally experience low of 3, so the uses 3.

I come back, (15-3) x 0.2 x 133 = 319.20 mls. that's what you say you are using. Lo Van gwerpen is because I respect as much, I decided on my own using the amount he gives in grams as if they were mls. (With the sole purpose of not using the high quantity of Van Gerpen, nor the least amount of DKenny ) And I want to tell me all they really have fallen to 3 if they are not above 9 (with NaOH, this is equivalent to 12.88 with KOH), more than there is a need to make a second reaction. If you have to make the methanol, water from the ceiling, but only when the tritación initial maturity of more than 7.La amount to draw when you need to be equal to half of the methanol used in the reaction.
In the end,. I think that the amount of acid was used more to the needy Only then will the substance and not arriba.Como you see I have a mixture d many things to see if you turn on a bombillito.
Caribbean Sea

Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post
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THank you Jon.
Registered: August 10, 2008Reply With QuoteReport This Post

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