Ok. I could probably do the photoshop thing, but I don't think you can wait for me to get the photoshop, and learn to use it, so let's see if I can clarify a little.
As I understand it, you are planning to put a relief valve to the heater tube, and you don't want to drill a hole in the tank to route the RV's outlet.
If that's the case, you can put a "T" between "V6_revers" and the tank, and route the valve's outlet to it.

But now that I think of it, I may have misread your posts. If what you want is to put a pressure relief valve for the tank (kinda like water heaters have), then you will have to drill a hole in the tank.
Personally, I wouldn't install a pressure relief valve for the tank. I don't think it's needed. You should drill a hole for the demething pump. If you do that, the tank will vent any pressure through the demething system, so you wouldn't need any RV.

That's right, the processor will vent naturally through the condenser - no need for extra vents.

There should be no valves in the path from tank to condenser to vent.

been away, had a muddy time, enjoyed it.

reading quickly through there seems a lot of concern about what acids can be used.

I think HCL will be fine in practice as it is used in the process, no matter what the theory of materials compatablity states. Time of exposure is a relevant variable. You can quickly rinse your needles.

Sulphuric will not raise the sulpher content of your biodiesel, look at all the acid base reactions that have been done using sulphuric without this problem.

You could use glacial acetic acid which is fairly cheap.

You could use phosphoric acid which is quite expensive.

You should not use nitric acid, which is quite expensive and one accidental exposure, to the commonly found sulphuric acid, away from creating a lethal by product which will kill you, your dog, your family and your neighbours.

Citric acid is solid when pure, commonly used by heroin addicts to make the base product injectable. Easily available from grocery stores that stock asian spices and cooking ingredients. Not very acidic (you can lick it) so I think it would take a large amount to do the job. Possibly unfeasibly large or possibly allowing a good safety margin against over acidifying. I don't know. May form some kind of solid gunge when it reacts as it is naturaly solid.

Hello everybody, I have good news!

On another thread, Tgomes just posted a link where you can find syringes and TEFLON NEEDLES!!!
And just so happens that teflon is one of the materials that can resist HCL, so we can kiss hastelloy goodbye...

Here's the link:

http://www.smallparts.com/

Hmm it's a flexible teflon needle, do you think it will penetrate a septum? Maybe, I don't know.

I can't help thinking that you are solving a problem that may not exist in practice. I suspect ordinary stainless will last a long, long time if you simply rinse them immediatly after use.

Or use one of the other acids.

Sulphuric will start to crack the soaps back to FFA before it leaves any sulpher in the bio. Leave enough of it long enough and it will convert the ffa to esters. Sulpher contamination has just never been a problem with any acid base reaction I have heard of. I can see no reason why this would be any different. It is cheap, easily available and forms a harmless salt on reaction with either catalyst.

The teflon needles I'm familiar with are rather soft and flexible. We use them for applying epoxy sealant to small devices, using an air-powered syringe. Only the tube is teflon, the part that connects to the syringe body is a different plastic.

Gentlemen, why not use a mazzei injector? it is made of PVDF (KYNAR) and the injection port has a check valve that consists of a teflon ball, Kel-F seat, and Hastelloy-C spring. if I'm not mistaken all of these materials are compatible with HCL. I can imagine a flow control pinch valve could be used on the tubing to regulate the dosage. The injector could be installed in a bypass configuration with restriction valve to create pressure differential. for clarification check link below.


http://www.mazzei.net/photos/injectors_products/bypass_assymb-complete-big.jpg

We have used the Mazzei venturis from the B100 supply site and they work well for this.

You could simply put a dosing vial with or with out a septum on top or connected to the venturi suction port.

They come in a good range of sizes and the suction flow is typically 1/6th of the inlet flow. This way you could either provide a single dosing amount in a fixed volume container or somekind of continuous feed for a specific period of time/dose.

GCG

quote:

Hmm it's a flexible teflon needle, do you think it will penetrate a septum? Maybe, I don't know.

I can't help thinking that you are solving a problem that may not exist in practice. I suspect ordinary stainless will last a long, long time if you simply rinse them immediatly after use.

Or use one of the other acids.

I will use sulfuric. I was giving the teflon needle as a possible solution for those that feel more comfortable with HCL.

About the septum, it probably won't penetrate it, but if the needle works properly, you probably won't need it. Just a small hole on the tube to get the needle through, sealed with epoxy should do the trick.

But I agree with you, sulfuric seems to be a better option. I hadn't thought about the sulfuric used in acid/base reactions, but now that you mentioned it, it seems like a no brainer.

quote:

why not use a mazzei injector?

I may be wrong but I think we are collectively overengineering our thought experiments when a little practical experimentation will yield a much simpler solution.

The septum idea seems relatively sophisticated and up to the task without complicating the system even further.

It seems to my that a bypass with a venturi and a site tube would accomplish the methoxide and acid injection as well as being able to see the color change without much complication.The venturi sure proved to work great in the GL1 day. How about it Graham...is there a problem with adding a venturi to the push pull main reactor as well as the rapeseed tank?

Hi Drewry,
That is what I am attempting to do. I used a venturi on the output of my inline heater for methoxide and acid injection and to operate a pressure switch to ensure the heater cant come on without liquid going past the heater. I just finished the plumbing the other night and ran some water through to test it out.
When I run it so that the water is pumped up from the bottom in the methanol recovery stage the pressure is too high and the suction line pressurizes I think either my pump or my venturi are to blame but I have yet to get a chance to get back at it

I will post back when I get it running!

Regards,
Jon

Just to help my understanding, the goal is to NOT apply suction until after the HCL is introduced, correct? (thus, hopefully preventing back reaction?)

If that's the case, is there any problem with having a 3/4 inch ball valve at the top of my processor that doesn't have a pipe attached to it...open up the 3/4 inch valve and slip down a viton/whatever tube to get it past the level of the valve and steel processor...dribble in the HCL solution over the required timeframe (hose keeps gasses from coming back out of the 3/4 inch valve while protecting any metal from the effects of the HCL), then re-close the valve before applying the suction via the venturi/rape seed oil contraption? Is that a bad idea, and if so, why? I imagine there is a reason other's aren't pursuing that thought, but I'd like to learn more by unerstanding what that reason is.

Thanks,
-Scott

Handcuff,

quote:

Just to help my understanding, the goal is to NOT apply suction until after the HCL is introduced

Correct.

quote:

any problem with having a 3/4 inch ball valve at the top of my processor

Nope that should work great! You could even just use a pipette instead of the hose for accuracy in my opinion.

Regards,
Jon

quote:

any problem with having a 3/4 inch ball valve at the top of my processor

As always, dosing chemicals above eye level can be dangerous... i'd avoid it if i could.

quote:

If that's the case, is there any problem with having a 3/4 inch ball valve at the top of my processor that doesn't have a pipe attached to it...

I'd think the biggest problem, besides the one ProjectPurity mentioned which is by far the most important one (HCL is REALLY nasty stuff), would be that, by injecting the HCL directly into the tank, you run the risk of over acidifying the BD. If you look at Graham's instructions for the HCL injection, he specifically says to stop injecting the HCL the moment the stream of BD changes color, even if the change is not permanent. So if you wait for the whole tank contents to change color, it may be too much.

bernyjb,

I don't know how much you've worked with indicators, or how many titrations you've done, but indicators tend to "flash" when they are approaching their color change point. In a titration, we are looking for a steady pink for at least 30sec.

That's not what Graham describes for this method. I think ideally, an indicator that went clear a bit more on the base side is what we'd be after, but by just observing the "flash" to clear, we're cheating the indicator. With that in mind, you mentioned that we're only looking for the site stream to change, but i think if you're not careful you could have a false reading by injecting too much into the stream at one time. Which is where good flow rate and slow chemical introduction come into play.

Hello all,

Just spent 11 hours teflon taping and tightening my main plumbing. Sadly I still have to do the foam trap and the centrifuge piping. I hope I am not doing anything wrong, I had no idea it would this long to plumb. I wondering if anybody has priced out the cost of plumbing the whole thing in copper? I do not know what the pitfalls of working with copper are, but with it being soft, bending the pipe to deal with the complicated configuration is got to be easier than putting in the multiple elbows, 45" and unions to make the thing work. All I can say for sure is that if my heaters leak, I am doing away with the horizontal safety feature and putting it vertically. Ok enough gripping.

I have 2 questions:

1. I am adding a PID and thermocouple. Where is the best place to locate the thermocouple, in the side of the tank or just after the heaters? I would think just after the heaters as that would give you the max temp which is what you really want. Kind of like hot water on demand as opposed to hot water heater - more efficient.

2. This might sound really dumb or overthinking. But to test my welds in my holding tanks, I put some water in them to make sure they were sealed and as a result some light rust was created which I removed. After I finish the plumbing and my fingers stop cramping (ok I lied one more gripe) I am going to calibrate the system by filling it up with water, 4 liters at a time making marks on the sight tubes, and then running the system to test the seals in the plumbing. Should I worry abut rust? Anyway to prevent it? Will it get in my final or will the filter take it out?

Doug

quote:

Originally posted by Doug Weiner:
. . . .Should I worry abut rust? Anyway to prevent it? Will it get in my final or will the filter take it out?

Don't worry about the rust. It will concentrate in, and be removed with, the glycerol. Any small amount that doesn't get trapped in the glycerol, and somehow gets by your filter, will cause no problems in fuel you plan to use on a timely basis.

quote:

bernyjb,

I don't know how much you've worked with indicators, or how many titrations you've done, but indicators tend to "flash" when they are approaching their color change point. In a titration, we are looking for a steady pink for at least 30sec.

That's not what Graham describes for this method. I think ideally, an indicator that went clear a bit more on the base side is what we'd be after, but by just observing the "flash" to clear, we're cheating the indicator.

Not much. Actually, I just made my first titration 2 weeks ago, so I don't think that could be considered as a lot of experience...

But, for what I gather, Graham has done more than a few:

"Very slowly (I mean VERY SLOWLY) dose 34% conc. HCl into the inlet of the pump and note the colour change. When you get to about 0.1% dosed volume, you'll see the deep red will lighten up a bit.

STOP adding HCL at this point.
The colour will darken again in a few minutes, DON'T add any more HCl or you will start to make FFA from the soap."

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/44410893...971060522#5971060522

I don't know if I'm reading too much into it, but that's the way I see it.
For what I understand, it'd be better to have too little acid (even if the lye is not fully neutralized) than too much.