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Topic: Designing a Biodiessel Process  (Read 17340 times)

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ciel

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Designing a Biodiessel Process
« on: April 29, 2006, 08:06:08 PM »
Hello,

Sorry if this question isn't really related to chem e problem. I'm wondering if someone could help me finding the price for sulphated zirconia as a solid acid catalyst ?

I have to design a biodiesel process. I need this info to calculate the prices of raw materials needed. My prof gave me a link but the price isn't there.

Thanks.


« Last Edit: May 01, 2006, 12:09:45 PM by geodome »

Offline eugenedakin

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Re: price
« Reply #1 on: April 29, 2006, 10:09:38 PM »
Hello Ciel,

Unfortunately, I do not know the latest price, but I have created biodiesel by many methods and not the one you mentioned.

Are you able to share this information, or is it proprietary (just because I find this topic quite interesting).

Sincerely,

Eugene
There are 10 kinds of people in this world: Those who understand binary, and those that do not.

ciel

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Re: price
« Reply #2 on: April 30, 2006, 02:45:26 AM »
wow ^^  I also think this is interesting! =)   

Ok. Let me explain about my project. By the way, I don't know what info you know so I just tell you anything that I think is important to know for people who want to make biodiesel. Plz correct me if I'm wrong =)

So, we have to design a biodiesel process - as I've said earlier. My prof gave 3 options, using a base-catalysed transesterification, solid acid catalysts, and supercritical methanol-and-CO2. My group chose the solid acid catalyst since the base requires many steps and the supercritical requires much energy. In the solid process, we don't have to buy lots of catalyst (right, since it's solid? I don't know how often we should change the catalyst though) and no neutralization step is required. The best solid catalyst tested was sulphated zirconia . The important thing to note is that "the acid catalyst group didn't leach off the solid surface under reaction conditions, but did leach in water, so contact with water must be avoided."  Thus, my group chose soybean oil, not waste vegetable oil, because soybean oil doesn't contain fatty acid (in the handout given, the waste vegetable oil contains some fatty acid).

By the way, my friend said that we can't choose waste veg oil because it will produce water. I don't understand, what kind of reaction are they talking about?

The reaction to make biodiesel is tryglicerides + 3 alcohol -> methyl esters + glycerol

mm.. I could emailed you a research article about this solid acid catalyst if you want. 

I also need help with the calculation. Furthermore, in the handout there is info saying "the higher heating value of diesel fuel is 45 MJ/kg, whereas that of biodiesel is about 39-40 MJ/kg.  I don't understand what this info is. I tried to find explanation about higher heating value but I still don't understand what this has to do with biodiesel.

Offline billnotgatez

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Re: price
« Reply #3 on: April 30, 2006, 03:45:51 AM »
Is this the real spelling
Sulfated Zirconia

Can it also be called zirconium sulfate
http://www.micronmetals.com/zirconium_sulfate.htm

Offline Donaldson Tan

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Re: price
« Reply #4 on: April 30, 2006, 09:56:44 AM »
The reaction to make biodiesel is tryglicerides + 3 alcohol -> methyl esters + glycerol

You mentioned that you don't want water in your process. Doesn't the esterification process produce water?

What is the reference for the abovementioned article? I hoped it's available on ScienceDirect.com
« Last Edit: April 30, 2006, 10:03:15 AM by geodome »
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

ciel

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Re: Price of Catalyst for Biodissel Process
« Reply #5 on: April 30, 2006, 10:14:20 AM »
I got the article from the online library.

The reference is

Kiss, A. A., Dimian, A.C. and Rothenberg, G. Solid acid catalysts for biodiesel production - towards sustainable energy. Adv. Synth Catal. (2006) 348:75-81

ciel

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Re: Price of Catalyst for Biodissel Process
« Reply #6 on: April 30, 2006, 10:16:41 AM »
To Billnotgatez : Thx!! I think that's what I'm looking for.

Offline Donaldson Tan

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Re: Price of Catalyst for Biodissel Process
« Reply #7 on: April 30, 2006, 02:53:25 PM »
I got the article on my thumb drive now. Interesting.

If you look at equation (1) on p76, u will realise that the chemical reaction produces water. All trigylcerides will produce water. Your friend's comment is still not totally invalid. He simply pointed out that the reactor feed must be dry to minimise catalyst leeching. Waste vegetable oil contains some water. The water comes from cooking food, etc. This poses a design problem of removing water from the waste vegetable oil. Imagine passing the waste vegetable oil into a dehumidifier to remove water content. The control problem you have here is that water content of the feed is not fixed. What sort of control strategy would you employ to remove moisture?
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

Offline Borek

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Re: Price of Catalyst for Biodissel Process
« Reply #8 on: April 30, 2006, 03:28:02 PM »
Won't heating oil above 100 deg C before feeding reactor remove water?
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Re: Price of Catalyst for Biodissel Process
« Reply #9 on: April 30, 2006, 03:33:21 PM »
Won't heating oil above 100 deg C before feeding reactor remove water?

If waste vegetable oil is volatile, I will loose both water and oil.

The control problem here is to determine the heat flux. The heat flux would depends on how much water is present in the waste vegetable oil. The water content in waste vegetable oil is not fixed, so heat flux throughout the process cannot be constant. However, the water content at the end of the dehumifidication process must be zero.
« Last Edit: April 30, 2006, 11:21:59 PM by geodome »
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006

ciel

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Re: Price of Catalyst for Biodiessel Process
« Reply #10 on: May 01, 2006, 12:04:35 AM »
Hi,

Is there a restriction on triglyceride content in biodiesel, in particular B20 ?  My group have to make B20 (20%biodiesel and 80% fossil fuel-derived diesel).

For example, for B100, my group found that there is a standard that says you can only have .02 mass% free glycerine and .24 mass% total glycerine (which I would guess to include mono-, di- and tri-glycerides).

-----------
We decided to purchase soybean oil (no fatty acid) from a suplier so we don't have to deal with water.
-----------
I chose to run the reaction conditioned like figure #4, the middle one, on page 78 (at 150 C, 60 minutes).

So, after the reaction, we will have triglycerides, methanol, methyl esters, and glycerol. The biodiesel is the TG, so how could we separate TG from other compounds?
Since I was given liquid-liquid equilibrium table (distribution of MeOH between methyl esters and gylcerol), I assume that when we do separation, we'll get 2 streams, #1 contains  TG, methyl esters, and MeOH, #2 contains glycerol and MeOH. Is this correct?  How will this separation work?

I think I should recycle MeOH. My prof said I might need a distillation column. I don't understand why.

---------


Offline eugenedakin

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Re: Designing a Biodiessel Process
« Reply #11 on: May 02, 2006, 10:18:31 PM »
Hello Ciel,

The answer to this question:

I also need help with the calculation. Furthermore, in the handout there is info saying "the higher heating value of diesel fuel is 45 MJ/kg, whereas that of biodiesel is about 39-40 MJ/kg.  I don't understand what this info is. I tried to find explanation about higher heating value but I still don't understand what this has to do with biodiesel.

Diesel fuel has a longer chain hydrocarbon than biodiesel.  When determining the exothermic energy when combution occurs (CO2 and H2O are produced).  If more carbon atoms are present, there is more energy produced (more MJ/Kg).  To really show you the distinction, methane (1 carbon) has a signifacently lower heating value than propane (3 carbons) or butane (4 carbons).

I hope this helps,

Eugene
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Offline eugenedakin

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Re: Designing a Biodiessel Process
« Reply #12 on: May 02, 2006, 10:26:33 PM »
Hello Ciel,

After reading the rest of the post, here is another answer to your question:

By the way, my friend said that we can't choose waste veg oil because it will produce water. I don't understand, what kind of reaction are they talking about?

The reaction to make biodiesel is tryglicerides + 3 alcohol -> methyl esters + glycerol


You can choose waste vegitible oil, but you MUST boil the water off by increasing the temperature above 100 C.  You will lose some lighter boiling vegitable oil, but you need to get rid of the available water.

The reason for removing all water is based on the reaction to make biodiesel.  The reaction you mentioned is in the absence of water.  When water is present, hand-soap (yep, the stuff that you use to wash your hands with at home) is made with water, triglycerides, and fatty acids.  If you have no water and the alcohol you mentioned, the fatty acids are converted to methyl esters, and the glycerine can be removed by settling.

I hope this helps,

Sincerely,

Eugene
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Offline eugenedakin

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Re: Designing a Biodiessel Process
« Reply #13 on: May 02, 2006, 10:38:36 PM »
Oooppss.. one more question to answer:

So, after the reaction, we will have triglycerides, methanol, methyl esters, and glycerol. The biodiesel is the TG, so how could we separate TG from other compounds.... I think I should recycle MeOH. My prof said I might need a distillation column. I don't understand why.

The Triglycerides have a lighter density than that of glycerol.  Glycerol will naturally form on the bottom of the vessel, and can be cooled to form a solid.  This settling may take some time (24 hours or so).  If too much methanol is present, methanol will emulsify both the glycerol and Triglycerides (it will appear as if the reaction did not occur)  I cannot remember if the methanol prefers the triglycerides or glycerine, but all methanol MUST be removed from the triglycerides.  If methanol remains in the triglycerides, it will cause the fuel--injection-pump to seize due to lack of lubrication.  The other negative aspect of methanol in triglycerides is that a sufficient amount will lower the decane value and you could cause a diesel engine to knock which causes internal damage to the combustion chamber, pistons, etc.

Recycling methanol is the preferred practice due to the economic advantage (its less expensive to reuse unconverted methanol than it is to purchase new methanol).  A distillation column is usually preffered since you will be removing 1) methanol, 2) triglycerines, and 3) very small amount of glycerine from the triglycerine fraction. 

You could also use the distillation column to create purified glycerine.  This will add dollars to your process stream.

Sincerely,

Eugene
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Re: price
« Reply #14 on: May 03, 2006, 03:32:39 AM »
Is this the real spelling
Sulfated Zirconia

Can it also be called zirconium sulfate
http://www.micronmetals.com/zirconium_sulfate.htm


This is not Zirconium Sulfate. Its Sulfated Zirconia which is produced basically from Zirconia (Zirconium Oxide) and acidic sulfonium ion e.g. from Chlorosulfonic acid.

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