Trompe, looking for more data

Mollison talks about these and there is evidence of them having been used in the sixteenth century to provide air in bloomery furnaces. In the nineteenth century a Canadian by the name of Taylor "discovered" the idea and used it in a couple of industrial applications, powering printing presses in one location and then more famously providing both power to tools and ventilation for a large scale mining operation.

Compressed air can run piston, rotary or turbine type engines. Expanding compressed air can provide refrigeration. Seems like quite a few benefits exist for using this technology, yet no one seems to be using it.

I think among the reasons it is not being used is a lack of information on what it takes to produce a usable quantity of compressed air. Taylor's industrial systems involve head heights in the hundreds of feet. Not exactly a home scale DIY prospect. But they were also running industrial scale operations. Not providing some refrigeration and maybe running a few pneumatic tools on a homestead.

Has anyone got information on what kind of pressure is needed to run standard pneumatic tools? Does anyone have the figures for what kind of head height a trompe would need to get to those numbers?

One of my thoughts is that even if you had to pump the water up to the necessary height, there are plenty of situations where you have to pump water up there for other reasons than a trompe (say for irrigation,or pressurizing your house water supply). If you are going to have to lift the water anyway, wouldn't it make sense to build a trompe into the system and recapture some of the energy you spent lifting the water in the first place?

I guess the key questions I am looking for answers to are how much oressure does it take to do useful work with compressed air, and how much head height does a trompe need to produce that level of pressure?

Anyone have any answers? Thanks in advance

Peter Ellis : Little immediate joy as each tool has a requirement for X Cubic Feet per Minute at approximately 90 PSI! See Link Below :

http://www.air-compressor-reviews.net/air-tool-cfm-requirements/

However there are many things that can be done at much lower pressures, Some cooling happens with any release of compressed gas

There are several adaptations to allow your to pump aerated water with efficiencies similar to A Water Ram, this aerated water can help
Reduce pollution and provide a virtually free supply of Oxygenated Water for Aqua-culture and can be useful with grey water!

I used the Permies.com [Search] Tab* to search for links to previous Forum threads key word 'Trompe' and got over 200 hits in 0.51 sec.
(This is one of the most under-utilized free features for You and All Fellow Members ) My search link below :


http://www.google.com/custom?domains=coderanch.com%3Bjavaranch.com&q=Trompe+&sitesearch=permies.com&client=pub-4768842087373098&forid=1&ie=ISO-8859-1&oe=ISO-8859-1&cof=GALT%3A%23008000%3BGL%3A1%3BDIV%3A%23336699%3BVLC%3A663399%3BAH%3Acenter%3BBGC%3AFFFFFF%3BLBGC%3A336699%3BALC%3A0000FF%3BLC%3A0000FF%3BT%3A000000%3BGFNT%3A0000FF%3BGIMP%3A0000FF%3BFORID%3A1&hl=en&sa=Search


For the Good of the Crafts ! Big AL

* [Search] tab is found at the top of the page in the Permies Toolbox, below the Permies Banner, and above the Permies Video of the Week.
leaving this Forum Thread located in the Alternative Energy forum will automagically limit your Search to that Forum.

Good luck and Good hunting ! A.L.

Late late note : There is a good wikipedia article on Tromps also a.l.

Thanks Al. I started my research today with a search of Permies and review of what was already here on the subject of trompes. None of the knds of specifications that help you figure out whether or not it can be useful on a small scale.

The information on the tools is helpful, and the commercial scale trompes of Mr. Taylor certainly produced plenty to run tools with those specs.

But how much head to produce 90 psi? Still looking for a comprehensible explanation of how to calculate the pressure and flow parameters of a trompe.

Peter Ellis : I expect that the worlds smartest fish has little concept of the medium it is swimming around in - Kinda like us and Air> more later !

If we start way above the earth and total up the hundreds of miles of Air pressing down on us the weight of all that air is less than 15 Psi, also called
1 atmosphere 1atm or one BARR

See link below :



http://www.asknumbers.com/bars-to-psi.aspx



6 atm(s) =90psi,
It is also true that 33 feet of fresh water = 1 atm ( 30' of salt water) so yeah, we can have modest amounts of Compressed air but at very low pressure !

A mining Engineer named Ben Declue got me through Algebra and Geometry, and tried to teach me P to the 7th power Proper prior planning prevents
piss poor results ! HE was an expert on the tromp system in Cobalt Canada ( Quebec?)

Unfortunately the physical plant was sold to a Energy company that was primarily in the Hydro power end, and did not have the expertise to keep the
system up and running ! I believe there is a Wikipedia Article on the Cobalt mine !

While this probably was in Textbooks 50 some years ago, Any college prof with some knowledge of this system must be 75 years old or older, I doubt
any current Mining Engineer Texts would have more than a line or two at best !

For the good of the Craft ! Big AL

Hello All,

I’m a new poster. A couple of years back I figured out that I love working in, designing with and contributing to the natural world. Then, I discovered the term “permaculture,” and my eyes were opened. I love this site.

Now, down to the question.  I have an engineering and medical background, for reference. I have also had the question about how deep to make a trompe that will produce a useful pressure. It is absolutely true that lower pressures like 30 or 40 PSI can be very useful around the homestead, but in my experience most pneumatic tools run on an average of 90 PSI, with varying flow rates. Flow rate is one of the things that  really excites me about trompe  technology. Because it is powered by a running (I.e. constantly replenishable) water source it is always compressing air, 24 hours a day 7 days a week. If you hook your trompe to a grid of air tanks (WITH APPROPRIATE PRESSURE RELIEF SAFETY VALVES) then you can potentially store massive amounts of useful mechanical power for free.  “Mind-blowing!”  

For me, a minimum of 90 PSI would be the goal. You will have to consider the needs of your homestead. As I understand it, the weight of the water atop the air bubbles is what causes the gas compression.  To find our pressure, we are interested in the weight the water  sitting on the air at the bottom of our system.

Here is a useful website for reference:

https://sciencing.com/convert-water-column-pounds-pressure-5666070.html

At the bottom of a column of water, a predictable pressure is generated. If you are looking at a “stack” of water molecules sitting in a hole in the ground, a pipe, or a garbage can, the 3D shape of the water doesn’t matter. It’s the height from top to bottom that matters, “head height”. Your water feature could be shaped like an upside down pyramid or a vertical pipe, but so long as they are the same height, “top to bottom” they will generate the same amount of pressure. It’s very counter intuitive.

At the bottom of a water column that is 27.78 inches tall you will create 1 PSI. Every time you go another 27.78 inches down, you pick up another 1 PSI.

So......  90 PSI x 27.78 inches = 2500.2 inches

2500.2 inches / 12 inches per foot = 208.35 feet.   210 feet for safety in calculations.

As far as I can figure, if  from the point that your water starts falling down the tube to the point that it hits the bottom of your tank inlet pipe is 210 feet, then you will get a steady stream on cool, dry, 90 PSI+ compressed air. That’s awesome!

Putting your system that far down presents some challenges, but personally with enough land, I think that is attainable for the DIY homesteader. I’m still brainstorming on the how tos, but I think with wise planning, persistence and some bravery, a lot of us can get there. May God bless your efforts.