Hey future,
I think your math is off by a factor of 2.
.37in x 3.14 x 46.76in x 55 = 2988 sq in Total ID SA
I appreciate you sharing your design with us.
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Based on some back of the envelope scaling from the known throughput of the BZB unit (maybe 180-200L/hr maximum with adequate cooling), and the heat transfer areas (33.79 sqft for BZB, 20.75 sqft for Future’s), one could guess that about 120L/hr is a reasonable estimation.
But then after I run those numbers, I look above and see that Future says that he’s getting 2+ gpm (450+ L/hr), which is way more than that. I don’t really feel like busting out my thermo textbooks to go back to first principles and figure out why. Maybe the 1/8" tubes on the BZB (if they’re still using that ID) are too small and saturate too fast?
If it’s really $60-100k (without heat/cooling sources of course) for 2+gpm of ethanol recovery that is by far the best value proposition on the market right now. And making me seriously consider scrapping my own design.
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Yup, entered diameter in place of radius 
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Couple variables and observations
-Solution was at 40-45c in the pre preheater barrel.
-The faster I ran the water flow, the faster she went all around.
(Remember I had it plumbed 10c well water at 7lpm, then into the 200k BTU propane heater, out at 80c and from there to the evaporator, from there to the preheater)
Obviously surface area is eventually the limiting factor all other things considered, but I’d love to see some math behind all of this. My initial observations we’re limited by a design flaw in v1.
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No matter how you look at it, it is a simple thermal energy equation. Yes, the surface area will help the rate of vaporization, but it is limited to the extent of energy capable of conducting via the surface pathway. Recirculation over the same pathway will yield similar results to more surface area so long as you have adequate heat energy to back it up.
At 200k btu (58kw), that thing should rip. You have enough heat energy for over 60gph of vaporization, the problem is re-condensating that massive heat load. Tap water will be hard pressed to keep up even at optimal flow rates and ground temps. Calcification of the HE and other issues come up too.
The math is pretty straight forward as the specific heat equation you can find here
You can find the isobaric heat capacity of ethanol based upon temperature here
Once you have your mass balance you can factor by the thermal conductivity capacity of 304 or 316 (whatever you are using). That info is here
You will have a theoretical maximum vaporization rate from the above info. I say theoretical because that math assumes you are operating with no energy losses. That also needs to be factored.
Our unit is 22kw on the front end, 22kw on the back end. We hit 100lph+ (25gph+). We also added tablet remote PLC control and are going to add some sensors to optimize. Come check it out at the Vegas show. Here is a teaser link.
https://www.instagram.com/p/BpzeDvcBci7/
Hope to see you there also Dustin.
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Here’s a calculator that can be used to determine approximate energy requirements for specific amounts of ethanol recovery. This is the ideal/perfect situation setup, actual heat recovery rates will be lower so long as you’re obeying the laws of thermodynamics… which everyone should do.
https://drive.google.com/open?id=1IOTKDyLu3lmWqnNgrOjpZUZNUFqjIwSQ
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Basically one of my main jobs at bzb is to test heater and chiller combos. The 36kw combo netted us 174L/hr but we offer multiple options as far as speed goes so you can upgrade heaters and chillers in the future and keep using the same steel and everything.
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Absolutely will! Can’t wait!!
Where do you think your current design caps out?
I’d guess 250L/hr before we expand it and add more surface area.
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Thanks for this!
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Price for steel only to Rotarua NZ?
It’s not quite legal there yet, but they are planning on cornering the global market 
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~1gal/hr per kw is ‘good’ efficiency.
you guys have covered a lot of the design difficulties so far.
they behave much differently with extract than clean solvent 
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When I was doing butane extraction, I always wondered why not use a Heat Pump. I thought it was inefficient that I had a device trying to keep one thing really cold and another device to make hot water. Using a single heat pump I could achieve both processes. Couldn’t you do the same for the FFE? Some type of heat pump that is dumping super hot water where you need and at the same time super cold water on the other side of the unit. Similar to a peltier plate in CPU coolers. One side is really cold, the other side is really hot. Or maybe they all ready do this… 
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Just get a water cooled chiller and route the water used to cool the chiller to what ever you need hot. It may need some supplemental help but should be more efficient than having heating and cooling separate
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Just figured out how they mate the tubes with the tube plate. Im thinking that everything on this design will be orderable online except the tube assemblies which I am considering having made locally here in California. Check out the basics of the tube expansion process that locks the tubes into the tube plates:
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Also, I know that for the evaporator side shell and tube is the obvious choice for heat transfer since it is going to need to be serviced regularly due to the nature of our solution. HOWEVER, after some discussion with @Lincoln20XX I wondered if a plate type HE would actually be a better choice for heat transfer when condensing the (presumably) pure solvent. Plate type heat exchangers are typically more compact for a given surface area and as such tend to be the more cost effective solution at larger scales. Read below for more and let me know if you can think of why this wouldn’t be the best solution for the condenser.
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An expander is a handy tool to have, you can trace the tool’s origins back to boiler making. Having a tighter fit up allows you to make a “fusion” weld, rather than filling with welding rod.
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I don’t think most industrial chillers are getting the cooling water hot enough to do what we’re after here (don’t know what everyone is running their FFE’s/Rotos at but I’d expect 70+*C), though I recognize that may depend on flowrate. Problem is, if you cut down flowrate of the cooling water to get a higher outlet temp, you’re going to cut down the ability of the chiller to chill the circulated coolant - it would be similar to running an air cooled chiller in a very hot room. In order to achieve a descent steady state you would have to drastically oversize the chiller to where it still has sufficient cooling capacity to condense with a lowered cooling water flowrate, and then I’d be concerned about what kind of impact that might have on longevity of the chiller.
I think 1244farms is onto something with the heat pump idea, though I don’t know enough about heat pump engineering to say whether thats a viable option or not. Most I’m aware of are for achieving temps human beings are comfortable in, which would probably be warmer than we’d want to condense at and colder than we’d want to evaporate at.
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