BIODIESEL & SVO DISCUSSION FORUMS





Page 1 2 3 4 

Moderators: Shaun, The Trouts
Go
New
Find
Notify
Tools
Reply
  
EFFECTIVE DRYING
 Login/Join
 
Member
posted Hide Post
Sam, the probe is in the air above the extraction fan, thats the beauty of the method. These things are only around £4 depending where sourced.

You can get a capacitive sensor that will go into the bio. They are very, very temperature sensitive. I have some which I am going to use via the arduino. We are doing some tests on the UK Biopowered forum but at the moment the results are a bit hit and miss.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post
member

posted Hide Post
UPDATE FROM SANDY BRAE:
I had a chance to talk with Bob at Sandy Brae this morning (sorry, yesterday was nuts).

Quick version: It depends.

Longer answer:
It depends on what we're referring to as "bound" with the water molecule and it's somewhat tricky.

If the H20 molecule is still in the form of an H20 molecule and is just "dissolved" into whatever is being tested (ie. Biodiesel or oil), then it appears that the Calcium Hydride can still react with it and detect the "dissolved water" in the liquid.

If the H20 molecule is "bound up" in something else. ie. it's been reacted into soap and really isn't an H20 molecule anymore, then it's highly doubtful that the calcium hydride will react with it.

If the H20 molecule is "dissolved" into a substance that's so thick (ie. tar or even fat or lard) that the petroleum solvent dilutant can't totally liquify it, it's possible that the calcium hydride won't be able to get to this H20 molecule and detect it.

So, if it's "dissolvable" by the dilutant and it's still in an H20 form, it's likely that calcium hydride can react with it to form a hydrogen gas and register on the Sandy Brae device.

With that said, in the case of Biodiesel, it appears that if it's in liquid form (hasn't gelled) and is tested by a Sandy Brae tester, the calcium hydride will still find the "dissolved" water in the sample and detect it.

This ties in with all of the tests that were performed with the Sandy Brae and Karl Fisher in which results from both tests were extremely close to each other each time they've been tested.

So, to conclude:
The Sandy Brae Water Tester will detect "free" and "dissolved" water in a biodiesel sample.
The US ASTM D2709 test will only detect "free" water that can be removed through a centrifuged sample.

Or in otherwords, Sandy Brae will detect more water in biodiesel than the ASTM Test even looks for. If you get under 500 ppm with a Sandy Brae, you're sure as heck drier than the US ASTM Test would find as well.

Hope that helps.

-Graydon




Utah Biodiesel Supply - Biodiesel Supplies, Parts, Kits, Tutorials, Decals & More
Utah Biodiesel Supply Blog - Tutorials, Articles, Pictures, & New Products!
Free Biodiesel Tutorial Videos - Learn to make Biodiesel through videos!
Utah Biodiesel Facebook Page - Stay up to date on all things Biodiesel!
 
Location: Utah | Registered: October 08, 2004Reply With QuoteReport This Post
Member
posted Hide Post
Thank you for that Graydon. I think you have cleared it up.

I have always found it "amusing" that using the ASTM test method, the biodiesel could possily hold up to 1500PPM dissolved water and 499PPM free water and still pass the ASTM requirements for water in biodiesel, the European EN standard would fail the sample at just 500PPM dissolved water.

As a point of interest, while the Australian standard for biodiesel is written as a mixture of the ASTM and EN standard, they use the ASTM method for detecting water and sediment.






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Hi Gordon & all. Thanks for the effort to nail that down. This is what I understood from the tests that Imake did. In south Africa the standard is for dissolved water not free water. I never had much success with a centrifuge for water removal. I was testing with a manometer and Carbide though.

DGS if the probe is in the air stream do you have to take into account the ambient RH%. Can you send me the link to the discussion on the forum you mentioned please.

Regards Sam
 
Location: Johannesburg South Africa | Registered: October 09, 2012Reply With QuoteReport This Post
Member
posted Hide Post
Hi Sam,

quote:
Originally posted by Sam Sleeman:
In south Africa the standard is for dissolved water not free water.
Regards Sam
Not wanting to be seen as being pedantic, but my research shows that the South African standard for biodiesel Water Content is:

"Water content: 0,05 % mass fraction max
ISO 12937: Petroleum products — Determination of water — Coulometric
Karl Fischer titration method."


If I am not mistaken, the Colometric Karl Fischer method does not differentiate between dissolved and free water- it reads total water, both dissolved and free.
You fellows get very dry biodiesel compared to us countries who use the ASTM standard Wink






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Hi Sam,
You don't have to take it into account but obviously it will affect it.
What i'm trying to say is that for any given set of circumstances, eg. ambient R/H, biodiesel temperature, volume of headspace, power of airpump, etc,etc there is a relationship between the biodiesel water and the R/H as read.

The figures I quoted a few posts ago are for my system, I'm sure yours will be slightly different but not a million miles away.

Here is a link; Post No10 on page 1 http://www.biopowered.co.uk/fo...hp/topic,2538.0.html

The beauty of checking the water this way is that once you have satisfied yourself that the 2 methods correlate you don't have to bother checking the water in the biodiesel. OK, once in a while to satisfy your self that things are working but thats all.

Since doing this I have never had a situation where the 2 readings, S/b and R/h are out of sync.

BTW Graydon, thanks for all the work, the outcome is exactly what I thought, Cheers.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post



Member
posted Hide Post
Hi Tilly. Pedantic You? perish the thought . and yes you are correct. Through out the content we have tremendous difficulties with water in petro diesel in rural areas. bad storage mainly. So that thinking spilled over to the Bio regs. Start off as dry as possible.
 
Location: Johannesburg South Africa | Registered: October 09, 2012Reply With QuoteReport This Post
member

posted Hide Post
quote:
Originally posted by Tilly:
Thank you for that Graydon. I think you have cleared it up.

I have always found it "amusing" that using the ASTM test method, the biodiesel could possily hold up to 1500PPM dissolved water and 499PPM free water and still pass the ASTM requirements for water in biodiesel, the European EN standard would fail the sample at just 500PPM dissolved water.

As a point of interest, while the Australian standard for biodiesel is written as a mixture of the ASTM and EN standard, they use the ASTM method for detecting water and sediment.


I couldn't agree more. I know the committee has kicked around the idea of testing it for dissolved water as well a time or two, but for now it's still sitting at just 500 PPM of free water. I think they adopted it from the diesel standard, but diesel can't absorb water like Biodiesel can (ie. that 1500 PPM of dissolved water).

What's even more interesting is it's a temperature sensitive test too. ie. test Biodiesel at say 75 deg. F using D2709 and it might pass, but let it chill down to say 40 to 50 and it might drop water out like crazy. Explains why so many people in the states report "water in fuel" lights on in their diesels when running even commercial Biodiesel. The producer will cry, "But it passed ASTM!!" yeah, but it can still have dissolved water in it that'll drop out if you let it get cold enough would be my reply.

It's a good reason to use a Sandy Brae or Karl Fisher for water testing. That way you get a good idea of what the true water content in the fuel really is.




Utah Biodiesel Supply - Biodiesel Supplies, Parts, Kits, Tutorials, Decals & More
Utah Biodiesel Supply Blog - Tutorials, Articles, Pictures, & New Products!
Free Biodiesel Tutorial Videos - Learn to make Biodiesel through videos!
Utah Biodiesel Facebook Page - Stay up to date on all things Biodiesel!
 
Location: Utah | Registered: October 08, 2004Reply With QuoteReport This Post
Member
posted Hide Post
Hi Sam,

quote:
Originally posted by Sam Sleeman:
...if the probe is in the air stream do you have to take into account the ambient RH%.
Regards Sam
In this discussion, listing the Relative Humidity without nominating the air temperature is pretty meaningless.
The "rule of thumb" is that for every 10 deg C the air temperature increases, the Relative Humidity is halved.
So if you are reading 40% Relative humidity at 30C headspace temperature, increasing the temperature in the headspace to 35C will reduce the RH to around 30%- a very big difference






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Hi Tilly please unpack this rule of thumb. I don't get the math of that.
 
Location: Johannesburg South Africa | Registered: October 09, 2012Reply With QuoteReport This Post
Member
posted Hide Post
Hi Sam,

"A useful rule of thumb is that the maximum absolute humidity doubles for every 20 °F or 10 °C increase in temperature. Thus, the relative humidity will drop by a factor of 2 for each 20 °F or 10 °C increase in temperature, assuming conservation of absolute moisture."
https://en.wikipedia.org/wiki/Relative_humidity

There are a several Relative Humidity calculators on the internet that will tell you the new relative humidity if you just heat the air without changing the actual amount of moisture in the air.

This calculator is probably the easiest.
http://www.lenntech.com/calcul...elative-humidity.htm

Set the outside temperature at 30C
Set the Relative humidity at 40%
Click on "Calculated grams of H2O per kg of air:"
"Set temperature inside closed space" at 35C
Click on "Calculated relative humidity inside closed space:
New Relative humidity is 29.3%

Now go back and change "Set temperature inside closed space" to 40C
Click on "Calculated relative humidity inside closed space:
New Relative Humidity is now 21.4%

As with most "rules of Thumb" there is a bit of leeway but you can see what happens to relative humidity as temperature increases

This message has been edited. Last edited by: Tilly,






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Thanks Tilly. This is where you add value to the forum.
 
Location: Johannesburg South Africa | Registered: October 09, 2012Reply With QuoteReport This Post



Member
posted Hide Post
I think we are missing the point here.

The object of the exercise is not to take the R/H as being accurate in itself, the R/H gives a relative figure to the water content of the biodiesel. The method works extremely well.

This message has been edited. Last edited by: Dgs,
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by Sam Sleeman:
Hi Bramm. The addition of water stops the reaction reversing and binds up the methanol. However when I do that I always make an emulation. depending on how sever the emulsion is I break it with more water & heat to about 40deg C. I then wash three times. then bubble dry. If I make sever emulsion I brake it with salt & water, then wash and then bubble dry. I found adding 3-5% water makes washing easy but I drain off the glycerol before adding water. I am building a vacuum processor which is now ready for testing.

Hi Sam Sleemman,
“You found adding 3-5% water makes washing easy but you drain off the glycerol before adding water”
May I ask how long time you leave glycerol to settle down before you start to make water washing?
 
Registered: October 07, 2015Reply With QuoteReport This Post
Member
posted Hide Post
Hi I'm really impatient so never longer than half an hour. Sometimes there is glycerol still not separated. I then transfer the raw bio and the 3-5% water mixture to the washing tank in the washing tank I spray another 30 or so litres of water for the first wash. Sometimes there is still some glycerol in the mix which is heavier than water and so settles to the bottom of the cone overnight, then there is water and then a thin layer of soap. I keep washing until the water is clear and the ph is the same as the tap water plus 1.

This is a clumsy way to do it. I always intended to do whole batch demeth and no water washing. However it has taken me a year to get that processor built and I am only now testing that.

You can also separate glycerol out very quickly with high voltage 7000 volts mille amp current
Neon tube transformer. I have not done this.
 
Location: Johannesburg South Africa | Registered: October 09, 2012Reply With QuoteReport This Post
Member
posted Hide Post
Hi Sam,
quote:
Originally posted by Sam Sleeman:
Thanks Tilly. This is where you add value to the forum.
Thank you for the kind thought.
I have always found that it is more useful to understand the world you live in.






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Hi Dgs,

quote:
Originally posted by Dgs;
I think we are missing the point here.
I agree with you on that.

quote:
The object of the exercise is not to take the R/H as being accurate in itself, the R/H gives a relative figure to the water content of the biodiesel.
You seem to have a very vague understanding of what Relative Humidity is.
Just to refresh your memory:
”Relative humidity is the amount of moisture in the air compared to what the air can "hold" at that temperature.”

In this situation, when you quote a relative humidity, it only has meaning if you also nominate the temperature.
For instance, You live in York.
I just looked at the weather report on the internet and it says that your current temperature is 17C and the Relative Humidity is 59%
If you now heat this air to 40C the Relative Humidity reduces to 14.1%
If you heat the same air to 60C the Relative humidity drops to 4%

Let's have a look at your post on the bottom of the previous page.
You said;
40% R/H = 250ppm water “

At what temperature?
Let's say the air temperature was at 40C when you took that reading,
If the air temperature had been 50C the Relative humidity would have only been 21.4%
If the air temperature had been 60C then the Relative Humidity would have only been 11.5%
Relative Humidity is relative to the temperature of the air.


quote:
The method works extremely well.
Which method works extremely well?
Heating the biodiesel and bubbling air through it to dry it.

On the site you linked to you posted:
”I dried another batch today using the turbo dryer and the cheap R/H sensor as reference. I left it at 60degs for 5 hours today as I couldn't get the R/H as read by the sensor lower than 30%. Last time it was 26% after 4 hours.”

Again, what was the air temperature you were reading the Relative Humidity at?
I would imagine the problem was that you did the Relative Humidity reading at two different temperatures on the two different days

I hope this has helped you have a better understanding






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
Member
posted Hide Post
Oh Dear Tilly,

quote:
You seem to have a very vague understanding of what Relative Humidity is.

I undestand this meaning very well thank you.

The R/H of the ambient air in York on any given day I am drying my bio is totally insignificant.

The sensor is measuring the R/H of the air exiting my tank through an extraction fan. This air has been bubbled through the bio by an aquarium pump which pulls air through silica gel.

When the biodiesel temperature is 65degs (held by the immersion thermostat) the pump is started. the air exiting the extraction fan throughout the drying cycle (other than a small heating period) is 33degsC

At the beginning of the drying cycle the R/H reads in the 60's
as the bio is wet after water washing (1000ppm+)

As the drying cycle continues after around 3 hours the R/H reading is down to the 26% mark ( if I do S/B at this point it is about 120ppm)

If I continue to dry the R/H will read lower with an obvious decrease in the S/B reading.

The ambient R/H has nothing to do with the reading.
The R/H reading is relative to the air moisture in the headspace of the drying tank.
The air moisture in the headspace is relative to the amount of water the biodiesel contains.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post



Member
posted Hide Post
Dgs, if you could list the temperature of the air as well as the RH maybe a table could be put together that would show ppm moisture and negate the requirement of using SB or KF. I did some work on RH of exiting air some years back so I agree with you that this is a good indicator of the moisture content of the oil. At that time I didn't have the SB tester only the weigh heat weigh which was a pain in the -ss.


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
Member
posted Hide Post
Tom, That is exactly what I do, as the biodiesel is held at 65degs the exiting air does not really alter very much in temperature.

I have only so far checked the 3x R/H levels with my S/B. The 26% R/H is what I usually aim for as when I have checked all the samples dried down to this level with my S/B all the results have been between 110 and 130ppm.

The results have been very consistant and as you say it eliminates the need for checking every batch.

Over the next few weeks I will graph the results and post it, will be interesting. There are a few others in the UK that now use this method of checking the water by virtue of R/H as the biodiesel is drying.
 
Location: YORK UK | Registered: April 27, 2014Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2 3 4  
 


© Maui Green Energy 2000 - 2014