Direct Gas to Liquid Heat Exchanger

Not a good idea - for any useful work out of a turbine you need high pressure, and I don't think what you are proposing will not cut it.

You should use an intermediate heat exchanger/boiler to run a high pressure steam turbine. You may want two of these exchangers to allow for one to be down for periodic cleaning.

What material and configuration of heat exchanger do you suggest? What type of gas would work best at these temps?

By the way, after posting I realized it should have been titled Direct Liquid to Gas Heat Exchanger.

There are many different configurations of boilers, but you would be looking at something like a "waste heat" boiler:

http://images.google.ca/images?hl=en&source=hp&q=waste+heat+boiler&um=1&ie=UTF-8&ei=RIOqSpmIFdPelAfBr-i7Bg&sa=X&oi=image_result_group&ct=title&resnum=4

You would want the corrosive sea water inside the tubes and, though I can't suggest the metallurgy, I could see them being titanium or a nickel alloy (or some other high alloy).

There is no "gas" involved - would be a regular water boiler - use the steam to run your turbine.

Thanks. Here's an image that I created of what I have in mind.

I'm not absolutely sure it would work, but it seems that it would. Input/comments would be appreciated.

I understood from your original description -

But the issue still remains - you will need PRESSURE (not simply temperature) to run a turbine - and it is neither here nor there whether you go with a reaction turbine or an impulse turbine - you will need to start with pressure.

The only thing that pops into mind is you could run a stirling engine off your temperature with your proposed sketch, but you said turbine.

The gas will have to be at essentially atmospheric pressure, and at the very most at the same pressure as the hydrothermal fluid AT THE POINT of contact (or else you won't get the fluid to flow)

So you need high PRESSURE "gas" to run a turbine.

I do understand that. I didn't include the results of a computer model on the system that might make a difference.

Assumptions:

Seawater Specific Gravity 1.03
2,500 m depth
3740 psi (258 bar) ambient pressure
350^o C vent temp
Surface vent temp 340^o C
Perfect insulation
12.13" (31 cm) ID pipe diameter
50% efficiency of steam turbine
Ocean temp at bottom 2^o C
Surface ambient 15^o C
Platform 30m above water line

Findings:

83 MW energy producible
Energy density (83 MW/area of 31 cm pipe) roughly 1 MW/10 cm² pipe area, or about 3.3x10⁶ more intense than solar radiation
>100m/sec (218 mph or 360 kph) steam velocity at surface
30 KT/day steam (25,000m³)
Useful surface temp 340^o C
Useful surface pressure 70 bar (1015 psi)
25,000 tons/day delivered to surface
25-35 kg solid/ton
25,000 tons x 25-35kg solids/ton = 625,000 kg- 875,000 kg solids per day

It is predicted that there will be 1,000 psi pressure at the surface, so as long as the gas pressure is less than that it should not impede the hydrothermal flow as far as I can see.

Correct assumption?

Alright - I am struggling to see how you will develop 1000 psi at the surface, unless your hydrothermal fluid is in a closed system - but then you wouldn't have the solids problem.

Please describe your hydrothermal fluid side more. How are you developing pressure at the bottom? In an open system the pressure will be the "head" of the depth of ocean - but then will 1000 psi at the top - you would be backflowing. So are you capturing "velocity" out of the vent, or what is going on?

Okay, that is what threw me - what you are proposing - you will not see "fluid" at the surface, you will see pure steam. Of course the value of 1000 psi comes from the vapor pressure of water at 350C. In this case, when perfectly insulated in a pipe, from natural convection this 350C water will begin to rise, and when it hits the "head pressure of 1000 psi it will flash into steam - and you will have a column of, say, 1/3 steam at the top, and 2/3 hot water in the lower portion.

I don't see that you have an issue then - tap off the 1000 psi steam from the top and run it through a turbine.

How do I get only clean steam, and not an acidic witches brew full of particulates which would damage a delicate turbine?

That's been the issue I'm dealing with. I want to utilize the steam, of course, but I've never imagined that it could be used directly because of those components.

How do you envision removing the steam and using it without damaging a turbine?

Distillation will give you particulate free - they would only be able to be carried by velocity.

But now that I think of it - you will probably have gases such as H2S - which would have to be removed for your direct contact exchanger anyway.

Moral of the story - go with indirect contact heating.

Can you please explain what you mean by indirect contact? What configuration would it have?

And yes, H₂S is definitely present.

By indirect contact I mean through a heat exchanger so that there is no mixing of the "hydrothermal fluid" and the "working fluid" (steam) for the turbine. So any shell and tube, plate, ... heat exchanger.

Have a look at the sketch I made so we are on the same page regarding "no water at the top of the column" (it is quite faint from my scanner - but hopefully legible)

http://yfrog.com/18oceanventp

Thanks. I was able to copy the drawing and dial up the contrast. Voila! Perfectly legible.

I see what you're saying and I appreciate your input very much.

Would you mind dropping me an email at the address below? I'd like to talk to you a bit off the record if I can.

Thanks again for taking the time to work with me on this.

The pressure is developed from flash steam pressure within the pipe. Remember that we're talking about 350^oC temperatures or higher. In the computer model there is a valve at the top of course, and the backpressure is selected so that the boiling point is at the surface.

There is also a hydraulic component to this. Imagine the vent in nature, with the water exiting out the top of the vent, obviously at a pressure greater than ambient pressure of around 3,000 psi. Just as that pressure acts on the ocean itself, it also acts on the fluid above it within the pipe.

Is that enough of an explanation?

No, that is not enough of an explanation - you CANNOT have water at the top of your vent.

The critical temperature for water is 374.2 °C and the critical pressure is 218.3 atm.

At those conditions water cannot be liquid. You can directly run any kind of turbine with that fluid. YOu can generate power till the pressure comes down to below turbine operating levels. As the water cools down below critical temperatures it starts boiling generating steam at a pressure given in steam tables. While this happens heat is removed from the fluid for latent heat of vaporiztion.

Ultimately a condition of large quantities of hot water at near 140 -150°C will be reached. This is a fairly simple thing to handle. You can use this to generate high pressures using a low boiling organic like acetone and generate additional power. Acetone turbines have been tried for generating power from hot springs.

Have you thought about what is involved in a 3 metre dia pipe working at 400°C and 220 bar pressure?

Probably a summersible turbine at the ocean floor is a better option.

Bioramani

Thanks for the input.

Are you taking into account the fact that this is not just seawater, but that it has ore and minerals of just about every variety. Here's an image from my site.

That's the reason I've never even considered directing the steam from the vents against a turbine.

I like the acetone suggestion for lower temperature fluid. Very logical indeed.

The pipe will not have 220 bar across it since there is fluid both inside and outside of it. There wlll be greater pressure at the bottom because of density differences, but as it rises there will be more pressure inside the pipe than outside it because of steam.

I agree. Still, the 'contaminants' are mostly inorganics and will not affect the basic properties of water. Under the specified conditions water will be supercritical and be a gas. If the suspended particulate contamination is high then waste disposal could become a major issue. If the vent is very deep under the sea level, you will have to account for the static head of water that has to come from the fluid. This will be one bar for every 10 meter depth. What will happen is that considerable power will go in what is in effect a giant pump delivering huge quantities of water against a hydrostatic head equal to the depth of the gas vent.

You can still materialize your idea by setting up a ocean floor shell and tube heat exchanger (water inside tubes vent fluid in the shell), generate steam, drive a turbine and condense the spent steam using the surrounding cooler sea water. Thermal syphoning can dissipate the condenser liberated heat. You can still add the acetone turbine to this scheme for additional power recuperation.

The engineering issues are not insolvable, the muck remains at the ocean floor and the massive structural engineering for suppporting large heavy vertical penstock pipes (with insulation) can be avoided.

Bioramani

I absolutely agree with that. The problem is that the "muck" is some of the richest ore anywhere on the planet and it's extremely valuable!

Easy to mine the ore from the settled mass on the ocean floor. bioramani

Actually, it's not easy at all. There's only one company that is making a serious effort to actually do so, Nautilus Minerals, and they are adapting surface strip-mining to the ocean. http://www.nautilusminerals.com/s/Home.asp

I shall modify my statement. Nothing deep under water will be easy. Depending on the settling velocity and loading of the stream vertical flow has problems. The repose angle of the solids concerned can cause a sudden blockage with attendant consequences. If there is a density difference (most minerals will be about 2.5 t0 3 gm/cc), you can instal a centrifugal (vortex) separator at the cap head. This is a passive chamber where the vent fluid enters tangentially, the spin generated settles out the solids while the fluid exits through the axial outlet. The concentrated slush is removed from below by suitable valving. At the topside any fines can be recovered. bioramani

I haven't read all the postings, but here's my two cents...

First, all of the locations you show in your video where these stations could be placed, are notoriously extremely powerful seismic areas - typically experiencing 8 + earthquakes and large tsunamis.

Second, I think you may run afoul of the academic environmental community. The discovery of these vents is relatively new, and may biologists, geologists, and zoologists are zealously attempting to keep these unique places on Earth in their pristine condition.

Anyway, I'm just sayin'.

Very interesting. I will read it completely and come back to you. It is a good idea and I am sure this concept will yield good results.

I see you're in Oman. The Saudis could really use this! If you have Saudi friends let them know!

the problems of:

1. Insulation

2. Severe abrasion and fouling potential of material entrained in 'hydrothermal fluid/steam'

3. Containment of 'hydrothermal fluid' nearing the surface, where differential pressure, combined with chloride and oxygen content, slurry of other metals and extreme temperature of the fluidcreate a substancial challenge

..... might all be more easily addressed if the system is designed to establish a high velocity vortex with the hydrothermal effluent.

if the effluent could be made to turn rapidly about a vertical axis, several benefits could be realized.

1. more dense material would be forcedto the outside where it could be more easily vented.

2. hotter/ less dense steam would concentrate in the center, near the axis. a heat exchanger placed in the center of the axis of rotation would remain relatively free of particulate and entrained liquid. it would also enjoy the bemefit of always contacting the hottest fluid.

3. with the colder (relatively) hydrothermal fluid on the outside, the need for insulation would be less demanding, and solids would be less likely to come out of soluution.

the rapid vortex would likely need more than just directing of the vent to be established and maintained. it would require external pumps to power high velocity eductors/ejectors, but this would likely be a small fraction of the total power produced by a plant such as this, and might end up being a very necessary aspect of the design.

benbenben

I'm not sure I understand.

Are you suggesting that the vortex be established within the pipe along the full distance from seabed to surface, or are you suggesting that it be established once the hydrothermal fluid/steam reaches the surface?

i am suggesting that a high velocity vortex be immediately established and maintained the entire length of the pipe which contains the hydrothermal fluid.

Ok, my question now is whether the solid materials, which in fact are some of the richest ores anywhere on the planet, can be recovered more or less efficiently with such a vortex system in place. How do you see such recovery accomplished?

focus on making this an economically viable power generation system as a stand alone entity first. you multiply the difficulty of this task if you attempt to build not only a new efficient family sedan,but also want to encorporate the characteristics of a dump truck. the ore will be readily available in the significant maintenance required in any system you choose... muck to some, or to others...a distraction at this time for you.... forcus on generating cheap power with the lowest initial capital investment to demonstrate the technology first.

Thank you for that advice. It is good, and I'll be honest. I've always envisioned that the first system would be a closed loop system which just makes energy. My reasoning was the same as yours. Go with the simplest first and then, after basic technologies have been developed and utilized, expand to the full capabilities of the system.

However everything I've talked about is real. The ores exist, and one doesn't have to be a scientist to recognize the potential for desalinating water. Those commodities are as valuable as the energy, and will not be ignored for long.

This discussion has been initiated to help me understand things that are beyond my field of expertise, and it has been extremely useful. I want to thank everyone who responded. Ultimately it is going to take a lot of brainstorming between a lot of engineers from many different disciplines to power your toaster from this concept.

It will be done. It's only a matter of time and determination.

I thought that one of the quotations that CR4 puts at the bottom of the page was extremely apropos.

"Determine that the thing can and shall be done, and then we shall find the way." - Abraham Lincoln

One of the questions to raise and answer is, are these types of sources prone to peatering out in time like the projects in California and elsewere.

Icelands projects have a practcality inuse but what will be as such in ventures such as the approach you have taken and what factual evedince is there to take to the bank.

Great questions.

Just like oil wells, there is a time when every individual hydrothermal vent is no longer useful. Nature closes all of them at some point. However, the process which makes them work remains, and when one vent closes another opens nearby. This has been documented by primary oceanic researchers. http://www.sciencedaily.com/releases/2001/08/010824081441.htm

This is unlike conventional geothermal energy where wells have to be drilled and water pumped in. Hydrothermal vents have been with us since the planet began, and it is they that created the surface ore deposits we now mine. A net search on the term hydrothermal vein will give more information.

It is possible to move the system to new vents as they open. The platform is moveable, the pipe can be disassembled, and the cable can be shortened or lengthened. No system can remain in one place indefinitely.

However, the life of individual vents can be anwhere from a few decades to 50,000 years according to researchers, so there is plenty of time to recover investments.

Please understand that I'm not an oceanographer. I've never ridden around in Alvin and looked at a vent out the window (though I'd take that chance in a heartbeat!), and I don't do the primary vent research. I must rely on others for that information, and in the 32 years since their discovery a whole lot has been learned about them.

I created the Marshall Hydrothermal Recovery System, the very first practical system offered to utilize this astonishing natural resource. Nothing is perfect, and I know there are obstacles ahead, but there isn't anything else that compares to the potential the vents offer.

This is going to require primary engineering on a scale as ambitious as that wich was needed to turn the concept of splitting the atom and the reality of a bomb into a reliable energy generating system used around the world.

The vents exist, their energy content is measured and undeniable, and the basic physics of the system is sound. That is something that can be taken to the bank.

I'd like to mention that I've created a list of references made up of people who believe in the physical soundness of the hydrothermal vent concept, and who are willing to lend their names and credentials to add credibility to the system.

It's not for publication, but for use showing to potential licensees and investors.

If you'd like to add your name it would be greatly appreciated. Please contact me at the email address below.

Thanks.