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What size pump for mixing what size reactor?
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What size pump for mixing how much oil?

Over the years, pumps seem to have become the favourite means of mixing in most biodiesel reactors made for home use, the BioPro being the only exception I can think of.
I am sure this is largely due to both the relative ease, and limited skill required, to install a pump onto a container with which to make biodiesel in.

The first Pump mixed reactor I saw information and photos about was Dale Scruggins. Touchless Biodiesel Processor It was a 40 gallon reactor and uses a 2hp centrifugal mixing pump.
Dale was an active member on this forum in the early day.

Over time, pump mixed reactors became more and more popular, especially after the introduction of the Appleseed Reactor.
However, no doubt due mostly to cost considerations, most builders used cheap Chinese ½ HP Clear Water Pumps for mixing instead of a big pump like Dale used.
These worked fine until the Warnqvest test came along and then a number of people found that they struggled to make biodiesel that would pass 3/27 in a single stage reaction or they had to mix for longer to pass the test using their pump mixed reactors.
It was clear that there is a size limit to the amount of oil a pump can mix and still reliably pass warnqvest in a reasonable time

It would be useful for everyone to get a better idea of what size pumps and mixing arrangement would be expected to achieve satisfactory results with what size reactor.
As a guide, from the time I started reading about making biodiesel the standard is that at 50deg C it takes 1 hour for the reaction to reach completion.
So what minimum size pump for what maximum size reactor will achieve a complete reaction in 1 hour?

For instance,
Biotom recently posted the ½ HP pumps were the minimum size for 160 litres batches and then he had to use a static mixer.
Jon Haron posted that his reaction passes Warnqvest in 20 minutes at 60deg C for a single stage reaction.
Murphy machines recommends
“1HP for batch sizes of 40 to 175 gallons
1.5HP for batch sized from 150 to 400 gallons
Note: These volumes are based on only 1 hour of mixing at 130 degF processing temperature.”

Without divulging trade secrets, If you would share your pump mixing successes and failures with everyone I am sure many people would find this information useful.

Photos and drawings would be great.






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
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I have a 500 gallon propane tank stood on end, I make 350 gallon batches almost always using the acid base method.
My pump is an open impeller centrifugal, four horsepower, the plumbing is all two inch.
It's a 150 gpm pump so it takes a little over two minutes to turn the whole batch over.
On the acid stage it'll take 10-11 oil to 2.5-3 in about three hours.
On the base stage it'll take the 2.5-3 to a 3/27 pass in about an hour.
 
Location: West Michigan | Registered: April 26, 2006Reply With QuoteReport This Post
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quote:
Originally posted by Tilly:
Murphy machines recommends
“1HP for batch sizes of 40 to 175 gallons
1.5HP for batch sized from 150 to 400 gallons
Note: These volumes are based on only 1 hour of mixing at 130 degF processing temperature.”

Without divulging trade secrets, If you would share your pump mixing successes and failures with everyone I am sure many people would find this information useful.

Photos and drawings would be great.


When employing a centrifugal pump to solve an application requirement, the horsepower of the pump is, more or less, pretty irrelevant to the design criteria.

Beyond the normal stuff like materials, seals, and other basic configuration characteristics, volume and pressure are normally the only variables to be considered and will dictate the horsepower (or in Aussi terms, the KW) required.

The only other characteristic I would bring into this is the design of the impeller.. Closed impellers produce more pressure and are generally more efficient, but in a biodiesel application such as we use, pump efficiency is the last thing we want.

A common misconception is that the mixing takes place in the tank or that the tank is the mixing vessel.. It is not. The tank is just a reservoir to hold everything. The bulk majority of the mixing takes place in the pump volute.


One of the reasons Murphys Machines HVI series pumps have been so successful is because of the impeller design I selected. The impeller is an open, rough finish, cast iron piece that is very inefficient.. This inefficiency causes a lot of "slip" within the pump volute (casing).. That slip is what is responsible for the superior mixing and blending abilities..

Hope that helps,


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Registered: March 09, 2006Reply With QuoteReport This Post
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Pumps: Parallel / Serial Connection

Pumps in serial - add head, pumps in parallel - add flowrates
http://www.engineeringtoolbox....el-serial-d_636.html

Pumps can be arranged in serial or parallel to provide an additional head or flow rate capacity.

Pumps in Series - Head Added

When two (or more) pumps are arranged in series their resulting pump performance curve is obtained by adding their heads at the same flow rate as indicated in the figure below.



pumps in series

Centrifugal pumps in series are used to overcome larger system head loss than one pump can handle alone.

for two identical pumps in series the head will be twice the head of a single pump at the same flow rate - as indicated in point 2.

With a constant flowrate the combined head moves from 1 to 2.

Note!
In practice the combined head and volume flow moves along the system curve from 1 to 3.

point 3 is where the system operates with both pumps running
point 1 is where the system operates with one pump running


Pumps in Parallel - Flow Rate Added

When two or more pumps are arranged in parallel their resulting performance curve is obtained by adding their flowrates at the same head as indicated in the figure below.




pumps in parallel

Centrifugal pumps in parallel are used to overcome larger volume flows than one pump can handle alone.

for two identical pumps in parallel, and the head is kept constant, the flowrate doubles as indicated with point 2 compared to a single pump

Note!
In practice the combined head and volume flow moves along the system curve from 1 to 3.

point 3 is where the system operates with both pumps running
point 1 is where the system operates with one pump running

In practice, if one of the pumps in parallel or series stops, the operation point moves along the system resistance curve from point 3 to point 1 - the head and flow rate are decreased.

++++++++++

Two smaller inexpensive pumps can be used in parallel to achieve the same performance as a larger more expensive pump, as well as providing two speed mixing and system redundancy.



 
Location: coldest N.America | Registered: May 03, 2005Reply With QuoteReport This Post
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The pump size relative to the tank size is just one part of the picture. One has to consider the whole system. There are ways to make small pumps mix well enough to make ASTM quality biodiesel.

I've posted a number of articles on this topic on my website.

Testing a Processor for Mixing Ability

Two relatively long threads on the subject, the first is filled with a diverse set of opinions on how to improve mixing.

Experiments in improving mixing

eductor beta test

There are a number of articles on the topic on my web site here:
http://www.make-biodiesel.org/...nt-and-upgrades.html


Rick
 
Location: Cowboy Country | Registered: December 06, 2004Reply With QuoteReport This Post
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Open impeller = good!
My batch size is about the same as fabricators, I use a pedestal mount MP open impeller pump with a 3HP, 3450RPM motor driving it. I believe it runs at around 150GPM. It has 2" pipe to the input and 1-1/4" pipe on the output unless its going through the boiler in which case its 1" pipe. I have a 3/8" nozzle that points into the bottom of the tank that works like a mixing eductor, I direct the flow through this when I add the methoxide (about half an hour).
Knock on wood, I have yet to fail a 3/27 after mixing for half an hour.
In hind sight I would have used a 3 phase 3hp motor with a VFD so I could turn down the pump when recovering.
Cheers,
Jon
 
Location: Wellington County, Ontario Canada | Registered: February 07, 2008Reply With QuoteReport This Post



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I like to post this to put Murphy in a bind because he hates plastic. He has to be a little nice because those are his pumps.

60gpm pumps on 92 or 98 gallon batches.
 
Location: Virginia | Registered: March 17, 2007Reply With QuoteReport This Post
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Plastic works fine, as long as the VO is heated in a metal container.
The problem is heaters in plastic tanks, and that's easy to avoid.



 
Location: coldest N.America | Registered: May 03, 2005Reply With QuoteReport This Post
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quote:
Originally posted by fuelfarmer:
I like to post this to put Murphy in a bind because he hates plastic. He has to be a little nice because those are his pumps.

60gpm pumps on 92 or 98 gallon batches.


You are leaving out one very important variable that most people don't consider... You "fuelfarmer" are accustomed and very familiar to industrial level processing operations and you probably have an innate sense for when you're about to cross a line or create an issue.

I don't like plastic because it increases the statistical probability of a catastrophic event.. I'm sure you would agree.. That's not to say it can't be done, only that steel is much safer in any failure modeling.

And lets face it, the greater majority of the people who make biodiesel for themselves are not experienced with the types of dangers that accompany our type of processing.. Oh sure, there are the well known exceptions like you and I, fabricator, heron, etc.. but most folks are not experienced in these areas and do not have the level of "industrial common sense" required to take calculated risks like using plastic.

But that's just my take on it..

I love that photo of my pumps!


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Registered: March 09, 2006Reply With QuoteReport This Post
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quote:
Originally posted by fuelfarmer:
I like to post this to put Murphy in a bind because he hates plastic. He has to be a little nice because those are his pumps.

60gpm pumps on 92 or 98 gallon batches.



One other thing.. Is that an old photo or do you have some super secret method for keeping things clean that I don't know about?


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Registered: March 09, 2006Reply With QuoteReport This Post
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Murphy, that is an old photo. The processor is in a shop that has a lot of dust flying around. I wish I had a magic way to keep things clean.

I will be the first to admit that plastic is not the best way to build a processor. Just as cotton fabric and wood is not the best way to build an airplane. But we all had to start somewhere.

And I like to post the photo just to stir the pot a little.
 
Location: Virginia | Registered: March 17, 2007Reply With QuoteReport This Post
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quote:
Originally posted by fuelfarmer:
And I like to post the photo just to stir the pot a little.


Eh.. if you were some newbie setting up in his garage or basement I might get a bit stirred up...

I'm fairly confident you know what you're doing, or at least have a big fat insurance policy for those times when things don't go your way..


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Waste Oil Heating - Biodiesel Systems
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Registered: March 09, 2006Reply With QuoteReport This Post



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Hi fuelfarmer,

quote:
Originally posted by fuelfarmer:
Just as cotton fabric and wood is not the best way to build an airplane.
You have a point. For the last 45 years or so the majority of high performance sailplanes have been made from plastic. Wink






 
Location: ลึก ประเทศอินเดีย | Registered: March 03, 2001Reply With QuoteReport This Post
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I have always used one of those Chines pumps, the latest being WelBilt which took over from the Northern Tool one.

I have always processed at 130F, but for a full 2 hours, not one, and have had consistent positive results. My batch size is 80L oil, 16L methoxide, single stage with 200L drum of chips followed by two resin towers and final filtered using a 2 micron fuel can.

Using this equipment in that config has been tested by GC and found to pass ASTM requirements on more than one occasion. Can't vouch for bigger or slower, but for me this combination has been successful.



** Biodiesel Glycerine Soap - The Guide
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Location: :-) Great White North eh ? | Registered: December 10, 2004Reply With QuoteReport This Post
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I use a peripheral turbine pump and not a centrifugal pump. Firstly my first and only Centrifugal pump had to labour with the glycerol and did not last long, and the Peripheral pump has had no difficulty at all over the years. Secondly the P-pump can give sufficient pressure (head) to drive the small centrifuge too.


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Location: Bottom tip of Africa, Port Elizabeth | Registered: January 20, 2010Reply With QuoteReport This Post
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get off the problem of using heater in plastic tanks..
please...


gee in 6 yrs of using heater in plastic tanks..no problems..

don't mount the heating element in the tank!!
hang it on a metal pole..no touching the sides..it works..

sorry..just a beef..its possible to it safely..been there and I'm still here..

back to the question..
what size pump? not a good question..better how much mixing?
1/2hp gear pump driving a static mixer with 20+ elements..killer mixing..think 2 to the 20 per pass mixing..

3-4 tank turns per minute?? killer mixing..

stop and think here...
the little pump from 10yrs ago..that one.. 1-2 turns in a 60gal tank..made good bio..
so is it turns/time..or just mixing time..or mixing time and temperature..
I've run batches at 60F or less for hours(10+)..that can out fine..

-dkenny


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Location: RTP, North Carolina | Registered: December 15, 2004Reply With QuoteReport This Post
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From the information people have given I came up with an equation to determine number of times a batch has to be pump (turns) per change in temperature from 130 F.

If people would post the following information I would like to test the equation.
flow rate of their pump or pump type (I can look up flow rate):
gallons for a batch
Process temperature
time in hours for mixing
 
Registered: November 26, 2012Reply With QuoteReport This Post
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flow rate of pump: 650 gph, but use 2 in parallel, so not TRULY 1300 gph, but more than 650gph of 1 pump...maybe with parasitic loss call it 1000 gph?

gallons for a batch: 35gal

Process temperature: 135-140F

time in hours for mixing: 2hr

So do I win access to the formula by participating? Wink
 
Location: Southern WI, USA | Registered: May 18, 2006Reply With QuoteReport This Post



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I will post equation after I get enough data points to know it is good.
BUt you win first place for posting data.
 
Registered: November 26, 2012Reply With QuoteReport This Post
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