Direct steam production?

Well guys, a venture out of the rocket stove forums.

Basically, i am wondering if it could be possible to make steam directly in the burner.

Immagine, a burner made out of a tube, with a supercharger at one end, a strong one, very insulated tube, so gaz combustion is complete, then you inject water, after the combustion is complete, in the very hot gaz stream. All this leading to a steam turbine intake.

I think it is possible.  I wonder if it would need a single tube of big dimensions, for the throttling. Or several smaller ones, so you'd light more or less tubes, for the power demand.

Thanks guys.

Sounds like you should aim for what is called a flash boiler.  Keep the water and exhaust separate though adding that water to the exhaust stream will probably mess up your draft. Use the heat over an exchanger and meter in small quantities of water to flash it to steam immediately. Safer then a batch boiler but be careful because steam is an unforgiving dangerous mistress.

Satamax, one of the things to think about would be the quality of the water/ heated gas mix as it contacts the impellers of the turbine. At the power plants were I work it takes very little to slowly destroy a turbine blade and if yours is spinning very fast, any imbalance can cause an explosion from a turbine failure. So we use super clean water and chemicals to keep down oxygen and minerals.

David, thanks a lot for your reply, but, draft is induced draft, by means of a blower.

Miles, ok, i didn't think about this one, i know about blade creep in gas turbines. I know about steam pitting on pistons and explosion chambers of water additioned combustion engines.

Do you think this could happen on small steam turbines, like the one they do for small cogen machines?

Thanks a lot.

Max.

I've done some reading on filtering exhaust with water.
Basically a fine spray of water particles in a closed stack capture chemicals and particulates from the exhaust that rises through them.
Down side is the water picks up a bunch of nasties, and then you have to contain and dispose of the polluted water.

I suspect steam generated by directly injecting water into a rocket stoves exhaust will produce a similarly polluted liquid.
Presumably liquid will probably be hard on any turbine parts it encounters.

On the subject of assisted draft, if you are putting energy into the system to induce draft already, removing more energy to make steam would suggest that still more energy would need to go into inducing draft.

Im biased on such matters, my research indicates that the simplest way to generate electricity from wood on a home scale is a charcoal gas burning IC generator.

Steam is seems more dangerous, less efficient, and/or more expensive.

William, duh, sorry, where do you see that i speak about wood, or rockets?

Propane, butane, hydrogen or whatever gaz is more likely to give me the results i want.

Oh! In that case, you should consider a  propane fueled generator.
Well,that is assuming your end goal is electrical power or inducing rotational motion.

William Bronson wrote:Oh! In that case, you should consider a  propane fueled generator.
Well,that is assuming your end goal is electrical power or inducing rotational motion.

Not at all!

Just a piece of friendly advice.  If you don't know what you're doing, don't play with steam.

Even the well educated professionals that know what they are doing occasionally end up with steam explosions that injure/kill people.  Even if you get lucky and don't hurt anyone, do you really want to destroy your rocket stove?

Besides, there are better, more efficient, ways to create rotation, electricity, etc.

Peter VanDerWal wrote:Just a piece of friendly advice.  If you don't know what you're doing, don't play with steam.

Well, i'm a strong advocate of safety. But do you think we would have evolved, if we kept on the safe side?  The pioneers in steam, have paid a heavy tribute. But also given us solutions, and safety practices.

Satamax, I guess I was thinking that you were injecting steam into the exhaust of a wood burning rocket also! Sorry.
Should be much cleaner with other fuels but might still pick up contaminates or change PH ?  I guess you would have to set up a small demonstration unit , being very careful, do some short runs and then inspect thoroughly to see how the machine performs and holds up? Maybe set up some before and after testing of water quality ?
You guys have had lots of experience with the improvement of rockets, sounds like you are moving to the next experiment.

Well Miles.

What gave me the idea, is this



I know each stage of movement change, of heat change etc is detrimental. Heating metal is detrimental. Etc.

I know that airplanes and some cars used water droplets injection in the intake, to augment the compression, and cool the engine, and exert more pressure onto the piston, due to flash steaming.

I know that gas turbines don't like extreme heat, and that steam turbines don't like it either. But steam turbines, are extremely efficient, besides the production of steam.

Heating metal to heat water, to make steam seems kind of idiotic, if you can direct heat the water.

Hence my "multi turbine"

You have a supercharger, blowing in an insulated tube, where combustion occurs, a bit like in a rocket. But with gases. Then, when the combustion is complete, water is injected, to cool the exhaust, but produce steam too.  And that mixture would hit a steam turbine. You have the two acting together, gases, and steam, into a cooled stream, not in an extremely hot flow, as in a gas turbine. But you still have the push from the exhaust. Which could prove interesting.  As you don't have too much heat creep.

This driving an alternator to power a car. Just an idea.

One of the methods to keep corrosion in check in steam power generation is to use high-pressure, high-temperature steam, such that the system is too hot for anything to condense out on the metal.

One of the problems I forsee, based on the explanation above, is the fact that moving from steam-producing temperatures to lower temperatures so as to not stress the metal would encourage condensation of anything inclined to condense out onto the corrosion-susceptible metal. Also, I think there might be an issue with the amount of steam needed to operate the system versus its cooling effect on the fuel in the combustion chamber. I think it likely that you will either achieve the combustion that you desire, but lacking much steam, or the water will put the system out, and you will have neither steam nor heat.

If you're likely to be using a fossil resource, it makes more sense to me to go out and find the best, most efficient generator design available and either buy it or make it/have it made. I don't think we have a propane or natural gas fuel cell yet, but until that's settled, I think that's the most effective, efficent bet.

-CK

Neat train of thought Satamax.

I'm seeing sort of a steam pulse jet with a Tesla turbine on the output end. Should be able to deal with the erosion issues better than a bladed turbine.

Edited to add:

Perhaps a high speed servo motor to act both as a starter and an alternator.

One of the best steam powerplants I felt had merit was Bruce Crowler's 6 stroke engine. In a nut shell, he is a cam shaft manufacturer and thus built a cam that would allow a diesel engine block to run a 5th and 6th stroke.


1. Intake of air

2. Compression

3. Power

4. Exhaust

5 Steam Power

6. Steam exhaust

The interesting thing was, not only did he get some extra power out of the engine, but because converting water into steam robbed the heat from the block, he did not need to even run a radiator to cool the engine. It was a great engine design, but felt it would never work because cars would have to haul not only fuel, but water too. And he thought that water would have to be distilled so as to not prevent fouling of the engine.

That is not really the case though if the engine was used in stationary, or massive engine applications. Think ships, locomotive and mining trucks here. And it would not have to be distilled water because on the railroad locomotives use regaular water in their engines with no antifreeze. They have a conditioner to keep the engine from fouling, but a temperature valve called a dump valve dumps the water if the water in the radiator gets too cold as freezing would cause immense damage. They do this because putting antifreeze in such big radiators is cost prohibitive.

I imagine a tractor trailer truck refrigeration engine of 6 stroke design being coupled to a generator. Izuzu makes them that are legendary in that they run for 30,000 hours autonomously, yet with treated water being injected in Crowler design fashion, they could have the same power with 1/3 less fuel. At 45 HP, such an engine could easily power a 20,000 kw generator; enough to run 2 houses, and the only thing that would have to be done is, modifying the cam and installing a water injector into the head.


6 Stroke Engine

Chris Kott wrote:
One of the problems I forsee, based on the explanation above, is the fact that moving from steam-producing temperatures to lower temperatures so as to not stress the metal would encourage condensation
-CK

Chris, sorry you didn't get my explanation right. it would be moving from gas turbine  combustion chamber temps, with peaks around 2500 Celsius or more, to steam producing temps. Superheated dry steam is happening in the range of 400 Celsius.

When you hit exhaust turbine blades, with very high temps, you get extreme blade creep, if not destruction. IIRC, toyota reached 1200C° on a gas turbine, with ceramic exhaust turbine.

If you get back to 400/600C° range, then the exhaust turbine is in a far safer territory, for the metal.

https://en.wikipedia.org/wiki/Turbine_blade