Distribution coefficients: input needed

Anyone have any empirical distribution coefficient data for biodiesel contaminants in a bioD/water solvent extraction system?

I'm trying to set up a counter-current wash scheme in a contactor column and would like to know what flow rates will ensure complete washing.

Here's my guessing of some distribution coefficients into water:

MeoH (>99%)
Na+MeO- (~95%)?
monoglyceride (<10%)?
diglyceride (<5%)?
salts of carboxylic acids (>66%)?
glycerine (>90%)

Any ideas or theoretical estimates can help.

Thanks.
Nick

Forgive a stupid question, Nick--

How important is it to remove the mono and diglycerides? If they are dissolved in the biodiesel, they should be okay, shouldn't they? I admit I don't have any knowledge here.

Discounting those two, it looks like the washing should go very quickly.

Ernie Rogers

Very important

They tend to coke injector tips and crystallize out of solution, at least to my understanding.

nicklockard said:

Anyone have any empirical distribution coefficient data for biodiesel contaminants in a bioD/water solvent extraction system?

I'm trying to set up a counter-current wash scheme in a contactor column and would like to know what flow rates will ensure complete washing.

Here's my guessing of some distribution coefficients into water:

MeoH (>99%)
Na+MeO- (~95%)?
monoglyceride (<10%)?
diglyceride (<5%)?
salts of carboxylic acids (>66%)?
glycerine (>90%)

Any ideas or theoretical estimates can help.

Thanks.
Nick

Click to expand...

This is why you are the guy in charge

I guess you are trying to achieve a setup that does a complete wash in one trip through the column, right? What kind of column do you want to use? Static packing, baffles, rotating contactor, etc?

Static packing bed material, a spray head for the water, a weir for water/bioD separation at the top.

I'm trying to determine if a single 55 gallon poly drum will effect a good strip in one pass w/o using too much water.

Thanks for the input

Suggestions?

Nick,
Here's a crude picture I drew up (no dimensions) of a reverse flow wash column I'll be building, based on some discussions we had over at infopop:


For simplicity in the picture, I just showed the biodiesel going straight up in a stream - but ideally you'd use some packed material to mix it up and increase residence time. Or some sort of stirrer, although I'd prefer static mixing.

If you want to calculate how tall the system needs to be, that's going to depend on how much soap is present in the biodiesel after processing - which is highly dependent on the FFA level of the feedstock (so what works for you may not work for everyone). Also, I'm not sure how quick the biodiesel rises up through the water - tough to calculate since the density of the biodiesel and water aren't going to be their normal densities, due to water and soap being in the biodiesel, and soap being in the water, and at varying rates as they go up the column.

Should be easier to just build it and see if it works, if not, make it taller.

I'm going to be using a column about 10 feet high most likely, with pretty slow pumping rates. The biodiesel outflow will then go through a rock salt drying column.

Thanks Mike. Good input. Any guesses as to distribution coefficients or where to find info? It's not like this kind of info is highly researched (yet), as it has had no practical, commercially widespread application importance till...well now

Oh, and I think I'm going to have a diffuser head for the biodiesel at the bottom too. What are you using for packing material and what is your source (please share .) I need affordable, obviously.

So, yeah, I'm going to take your advice above and build a 55-gallon poly drum unit first. If it isn't effective, I'll weld another drum to it to increase the height of the column.

For other readers: counter-current wash schemes such as we are discussing in this thread minimize water usage and maximize its cleaning power, reduce equipment footprint, but more practically for the homebrewer, they reduce automation needs! That means fewer PLC controls, fewer electromechanically operated valves and pumps, and substantially reduced cost. It's worth googling "counter current wash design" or finding an old textbook. My boss is loaning me his old engineering text for this project

nicklockard said:

Thanks Mike. Good input. Any guesses as to distribution coefficients or where to find info? It's not like this kind of info is highly researched (yet), as it has had no practical, commercially widespread application importance till...well now

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Nope, not sure where you might find them. Perhaps from Van Gerpen at U-Iowa? (oh wait... he moved to U Idaho I think...).

You mention glycerides in your first post - I don't think they're removed much at all by water washing.

Oh, and I think I'm going to have a diffuser head for the biodiesel at the bottom too. What are you using for packing material and what is your source (please share .) I need affordable, obviously.

Click to expand...

I was thinking about using marbles (I think that's the technical term ).

So, yeah, I'm going to take your advice above and build a 55-gallon poly drum unit first. If it isn't effective, I'll weld another drum to it to increase the height of the column.

Click to expand...

Sounds like a plan. Remember, the height of the water outlet will determine the level of the biodiesel in the column (and the height of the water in the column will be right at the water inlet). It's probably easiest to start with a fixed biodiesel outlet, and have the water drain outlet be adjustable to fine tune it. You could calculate where you want it, except that the densities of the water and biodiesel layer will be skewed by the water in the biodiesel and biodiesel in the water, and soap in each. So it's easier to not calculate it, and just keep the outlet level adjustable.

For other readers: counter-current wash schemes such as we are discussing in this thread minimize water usage and maximize its cleaning power, reduce equipment footprint, but more practically for the homebrewer, they reduce automation needs! That means fewer PLC controls, fewer electromechanically operated valves and pumps, and substantially reduced cost. It's worth googling "counter current wash design" or finding an old textbook. My boss is loaning me his old engineering text for this project

Click to expand...

Are you doing a PLC system? We're about to start working on one.

These also work great if the water and biodiesel are warm (any washing is better with warm water/biodiesel).

Sooner or later on the PLC

From what I hear, it is a moderate learning curve. Unless we can write a V-basic (my pardner, not me ) script or program and use something like: Opto-22 brand IoLogic(?) (expensive, as I recall), then a PLC box will work fine!

My key goal is to simplify and streamline out as much automation as is right, but no more.

Marbles? Will that promote enough mixing/agitation, or will the biod rise up in a contiguous stream? The packing material I am most familiar with looks like those Dorito's Curly chips, but made out of clay. I can't seem to find any yet. I'll keep googling.

I was initially thinking of using LabView and a NIDAQ card for automation, but our instrumentation person here convinced me to go PLC instead. I don't have any experience yet with PLC though. I do have a fair amount of programming experience though - and lots of computer science students available to do any programming we need.

Right now I'm drawn to the idea of using solid barium monohydrate catalyst instead of KOH, which should greatly simplify automation (no need to titrate and measure out a certain amount of catalyst - although you would need to replace the barium catalyst every now and then, due to some of it being eaten by FFAs to make soap).

I'd think that marbles should provide sufficient mixing, but I'm not sure. You could also build baffles into the column to facilitate mixing, although I think having some sort of packing material in there should work better.

Could you use a flexible hose as the inlet for the biodiesel to encourage mixing? (think unattended firehose!) Maybe a rotating nozzle like the outputs on a hot tub?

Maybe a spiral of material inside the stack.. this could be a good way of making your barrel "taller" without making your barrel taller... but its a little more complicated to make.

moondawg

Dawg, the whole tank will be filled with packing material...oh, I see what you're saying: put a seive or strainer around the bioD entry at the bottom and allow it to flop around like a firehose.

Funny you mention that, I was tempted to jet my reaction mixture in that way: randomness is good! But I decided on a fixed nozzle shooting a stream straight down into the Rx mixture.

Problem with the 'firehose idea' viz the wash column is that I want to depend on garden hose pressure to lift the water up, and I want to depend on gravity-driven differential densities to cause bioD/water to switch places. There won't be much pressure at the bioD inlet unless I add another pump. But, I'll give this some more thought.


The idea of a corkscrew is a great one! What material would you suggest? Maybe I could approximate a corkscrew by strategic placement of baffles.

{Mike, I was going to add diffusers and baffles }

Necessity is the mother of invention.

Quick idea for a "corkscrew:" Radiator fans from junkyards. Lay them flat, on top of each other. Either find some that are too big, and cut them down, or find some too small and use them to setup a gentle "swirl" in your flow. Or, find some just the right size. There would be some room in between the blades for material to sneak through, but it might be enough.

As for the "firehose" inlet, you could also just use a "ring" around the bottom of the stack, with holes poked in... Kind of like the big, long, water fountains they use for football practice in the summer.

moondawg

You mention glycerides in your first post - I don't think they're removed much at all by water washing.

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From what I understand, monoglycerides are easily removed during washing. Tri- and Diglycerides are a different story.

nicklockard said:

Marbles? Will that promote enough mixing/agitation, or will the biod rise up in a contiguous stream? The packing material I am most familiar with looks like those Dorito's Curly chips, but made out of clay. I can't seem to find any yet. I'll keep googling.

Click to expand...

Broken glass makes a pretty good packing material. Put a bunch of glass in a barrel and pound it up till the pieces are mostly an inch or two wide, then screen out the fines,

Thanks There's a recycling center in Eugene that always has scrap glass.

nicklockard said:

From what I hear, it is a moderate learning curve. Unless we can write a V-basic (my pardner, not me ) script or program and use something like: IoLogic(?) (expensive, as I recall), then a PLC box will work fine!

My key goal is to simplify and streamline out as much automation as is right, but no more.

Marbles? Will that promote enough mixing/agitation, or will the biod rise up in a contiguous stream? The packing material I am most familiar with looks like those Dorito's Curly chips, but made out of clay. I can't seem to find any yet. I'll keep googling.

Click to expand...

I have a suggestion instead of marbles. For my aquarium there are some things called bio balls. There are different kinds and some types of those might work for you.

Here is a link for an example:

http://www.marinedepot.com/aquarium_filter_media_biological_filter_media.asp?ast=&key=

moondawg said:

Could you use a flexible hose as the inlet for the biodiesel to encourage mixing? (think unattended firehose!) Maybe a rotating nozzle like the outputs on a hot tub?

Click to expand...

The thing is, you want the biodiesel to be pumped in pretty slowly, since you want a fairly long residence time in the wash column.

Lightflyer1 said:

I have a suggestion instead of marbles. For my aquarium there are some things called bio balls. There are different kinds and some types of those might work for you.

Here is a link for an example:

http://www.marinedepot.com/aquarium_filter_media_biological_filter_media.asp?ast=&key=

Click to expand...

I'm sure the ceramics would work excellently, but they're insanely expensive.

Okay, there've been some excellent suggestions here. Thank you everyone. My home brew partner is going to go to a home and garden store and look up price per cubic yard for 1"-2" sized pumice stone.

Assuming the pumice stone is not prohibitively expensive, I think we're going to weld the butt ends of two opaque white poly barrels together and pack it with 2/3 broken glass and 1/3 pumice stone. I really like the radiator fan as a swirl-promoting baffle idea too, so I'm going to a scrap yard to find 5 or 6 to place every ten inches of height or so.

The opaque white poly barrels are $5.00 each. We think it will probably be cheaper to weld them together than to install bungs, which run $55 each(ouch!) at usplastics.com. So a single-barrel setup would run at least $120 in parts, whereas a double-barrel setup runs the cost of the HDPE welding rod yet provides more washing. It will be quite heavy though so we'll brace it sturdily and lag it into wall studs for earthquake protection.


Keep these ideas coming. Does anyone have any ideas of the partition coefficients? We are going to do everything to prevent mono and diglyceride formation upstream of course. Also, Mike, what's the cost and how hard is it to locate bulk quantities of barium monohydrate? Please feel free to share your ideas here. We are always looking for ways to simplify, reduce automation, reduce clean up problems, and preserve quality.

Thank you everyone! We will try to document the build and construction photograpically of this wash column in following posts.

Packing material found: broken toilets and sinks!

Really! Went to Bring Recycling in Eugene and they had all these broken toilets, broken tile, broken stone counter tops, and broken sinks, all porcelain or stone. Loaded up about 700 lbs of the stuff.

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We're gonna have to smack it into the right size range with sledge hammers, but that shouldn't be too hard. The current size is 4-8 inches average. This stuff is really sharp. I plan to also use some old beer bottles too that I haven't yet returned for deposit...knew those would be useful someday Oh, I'm going to make a 2X4 frame around chicken wire for the screening of fines.

Last weekend I picked up some radiator fans from the U-pick junk yard (2 metal ones) that I will use for a bottom and midway baffle. Cutting the plastic barrels is going to be the hardest part of this I think. I've roped my co-worker John (who's a bit of a genius with custom fabrication) into welding the poly drums for us...might have to supply a nitrogen bottle however for the best weld. Also, I've decided to put the whole thing up on caster wheels for ease of maintenance. The sum***** is going to weigh 750 ++ pounds. Brian built the 2 X 4 base to which the wheels will be attached.

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nicklockard said:

Also, Mike, what's the cost and how hard is it to locate bulk quantities of barium monohydrate?

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Not sure what the bulk price is... I've been meaning to look into it for a while, and haven't gotten around to it. Your best bet is probably to check with local chemical supply places (places that supply industries though, not academia/research, since those places are too expensive).

I don't know if I'm too late, or if this information will help at all, but -

I spoke with our PhD chemist here at work. He thinks the distribution coefficients will have a lot to do with turbidity, time, temperature and viscosity. He thinks it could be modeled after a known petroleum solvent of similar boiling point and viscoisity.

He's not familiar with biodiesel, but likes to tinker with stuff. I'm going to give him a bunch of information and play around with it during occasional downtimes.

Good luck, and keep up the good work!

Thanks!

FYI: the biodiesel will be entering the bottom of the stack at 45-55 Celcius. Water temp will be ambient...typically 14-18 C, average droplet residence time will be whatever theory predicts for a well-baffled column ~50cm wide by ~160 cm tall packed with 5 cm(average) material...bioD made this way will have a viscosity range from 6- 50 cP (changes as it cools.)

I'm still waiting on my boss to remember to bring the book so I don't know what the theory predicts for residence time. I'm flying blind right now.

Edit: had farenheit on the brain for bioD temp.

nicklockard said:

Static packing bed material, a spray head for the water, a weir for water/bioD separation at the top.

I'm trying to determine if a single 55 gallon poly drum will effect a good strip in one pass w/o using too much water.

Thanks for the input

Suggestions?

Click to expand...

Oops, meant to say a dropping head for the water. Also, we may not need a wier..or maybe so...just gonna have to build it and see.

Nick,

Just throwing this out there. I know my HD like the back of my hand, since I've spent at least 20 hrs a week there for the last 8 years. Let me know if there's anything that may be purchased there and I can do the legwork for you.
Also I would be willing to donate a 20% off coupon to HD for the project. One time purchase only, expires 4/30/06.

I won't use it. It was our Xmas gift this year. Cheap b@stards. Last year we got $25 gift cards. This year I'd have to spend $120 to get the same value.
But I digress.......

Let me know and it's yours, but plan to get the most out of it!

Keli

Thanks Keli, we'll probably need it for the plumbing. 1" NPT threaded black iron.

Stainless steel runs $122/foot, teflon runs $20/foot

Anyone know any plumbers with lots of scrap SS pipe? We can't use PVC or copper. Brass would work though.

nicklockard said:

Thanks!

FYI: the biodiesel will be entering the bottom of the stack at 45-55 Celcius. Water temp will be ambient...typically 14-18 C,

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The warm biodiesel will definitely help. Have you thought about also using warm water that's heated by being used as a coolant in the methanol recovery stage before washing? Using tap water as the condenser coolant during meth recovery gives you nice warm water, which can then be used nicely in washing - pulling out more soap than cool water.

Brilliant. I will once I get meOH recovery set up...so much to do, so much to do