Boiler that also generates electricity

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Old 02-16-04, 05:56 PM
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Boiler that also generates electricity

Just saw this article in one of my latest engineering journals. A couple of manufacturers in Europe have produced a gas boiler that also generates upto 1KW of electricity from the waste heat apparently. This is for domestic use. Any power unused by the home can be put back on the power grid.

Here is a link to the diagram in the article -

http://www.geocities.com/rperinpa/boiler_gen_lowres.jpg

Sorry for the poor lighting on the picture. I cannot justfy the cost of buying the macro flash attachment
 
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Old 02-16-04, 07:10 PM
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Rev,

The page is not working..
 
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Old 02-16-04, 09:53 PM
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Not sure why - works for me. Someone else had the same problem when I posted a link to a diagram in the electrical forum. Try copying and pasting the link in the browser directly and see if this helps.

It may be a setting you have to adjust in your user cp.
 
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Old 02-17-04, 04:22 AM
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The link don't work.. But the copy/past does..

Ok, intresting set up..

So from what I understand in the drawing, the combusting air is what drives the alternator??

Is this systme already out on the market out there?
 
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Old 02-17-04, 08:47 AM
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That looks like it is trying to do like our Total Power Concept engine we have had here for years. Runs on LP ,Nat gas ,diesel or gasolene. Makes the electric, heat, hot water and A/C for a building. All in one unit. ED
 
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Old 02-17-04, 03:11 PM
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It seems like the hot waste gases drive something called a stirling engine which in turn drives the generator. The links to the 2 manufacturers can be found at

www.microgen.com
www.whispergen.com

Some info on these sites on how it works.

Ed - I think the idea here is to extract the waste heat and make electricity from it instead of venting it in a boiler that is identical to one without this feature. I think what you're talking about is designed in the first place to produce all the sorts of thing you mention but this being the primary function rather than to make it more energy efficient.
 
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Old 02-18-04, 02:07 PM
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The Stirling engine was invented by Robert Stirling in 1816. So it has been around for some time. If you search the web for it, you will find a lot of information and illustrations on it. What is unique about the stirling engine is that it is not an INTERNAL combustion engine.
 
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Old 02-22-04, 02:07 AM
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Generate Electric power

Wonder if it's any more efficent than cogeneration.
Like using a Nat gas engine to generate electricity and then using the waste heat from the exhaust and engine to heat hot water which then heats the building ?
We have one here in AUCKLAND on an old peoples Home.
 
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Old 02-22-04, 02:33 AM
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I wonder. I guess this is a good use of the waste heat.

That reminds me of a short wave transmitter site I visited some years ago. Each of the ouput amplifiers that drove the antennas were rated at around 1 Megawatt. The amps were all of tube technology (if people still remember electronic valves before transistors). I think they still use tubes (giant ones) as this level of power is too much for solid state devices like transistors. These amps were operated in class B which meant that around 250kW of waste power was dissipated in the anode which was a hugh metal disc bolted on the top of the giant valves. Water was pumped through the anode for cooling and then used for all the heating needs of the building.

Several of these amps were operated at any one time so there was always plenty of heating and hot water.....
 
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Old 02-22-04, 05:23 PM
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Narroc

Cogeneration is used with manufacturing. Natural Gas Fuel Cell, which is much different than Cogeneration, is probably what they are using in Auckland. If you search the web for either of these you will see a lot of applications.
 
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Old 02-22-04, 11:02 PM
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Co generation

resercon.

?????????? what ?????

No I understand it is co generation they are using ????

Don't think they are making nat Gas fuel cells ???
 
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Old 02-23-04, 12:32 AM
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I also don't get this. Surely this depends on the size of the cogeneration engine. I'm sure there are small ones that can do smaller building like the one Narroc mentions. I had a quick look on the web and there was even mention of some manufactureres attempting to develop cogeneration engines for use in individual homes (10kW).

Don't understand why it can be used only in manufacturing.
 
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Old 02-23-04, 09:39 AM
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Im with Narroc The units I said We called Total Power Concept . Could be the same as the Cogeneration engines .Run on one fuel any kind. Make the heat and hot water off the unit itself and produces the electric for lights and the AC Or some will run a chiller for the AC.

Have also worked on boilers where the vent stacks worked as peheaters for hot water to go into the boiler. That in turn ran the steam generators for electric power. Then the steam was sent to building all around for heat.

Just .02 cents more ED
 

Last edited by Ed Imeduc; 02-23-04 at 10:22 AM.
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Old 02-23-04, 10:07 PM
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Co-generation is used in the production of electricity from waste heat. An example of Co-generation is not a natural gas fuel cell. Process - A converter changes the natural gas into a hydrogen rich gas, which is used to produce electricity. The waste heat from the conversion is used to heat the domestic hot water.

An example of Co-generation is a steel mill, where the waste heat from manufacturing steel is used to produce electricity.

A power plant that produces electricity by using steam to turn turbines. The waste heat from the turbines is used to heat municipal buildings, is not Co-generation.

Using the heat from the air conditioning process to heat the domestic hot water of the building, is not Co-generation.

A company that uses heat to mold plastic to make dash boards, uses the waste heat from the process of manufacturing to produce electricity is Co-generation.

In other words, Co-generation is the production of two separate products, where one of the products must be electricity. And the electricity must come from the waste heat of the production of the other product.

http://www.pnl.gov/fta/5_nat.htm

This site discusses natural gas fuel cells that uses the waste heat from the conversion to heat the building and/or domestic hot water. It is not Co-generation because it does not meet the criteria for Co-generation.

There are literally thousands of websites that discuss Co-generation that explain Economy of Scale and it being an Economically Viable Solutions for industry. What all of this information explicitly implies is that Co-generation is not economically viable for small commercial and residential applications.
 
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Old 02-23-04, 11:21 PM
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Co Generation?

So are you saying that a plant where the nat gas is used to power a engine which generates electric power by driving a generator from the flywheel and the waste heat from the engine is then used to heat the home is not co generation??
The word co must be short for Combined surely.
Don't know about the production of hydrogen fuel cells I think a (the) gas engine would produce water vapour and a few other things but hydrogen fuel cells ????
If this is not co generation then what is it ?
 
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Old 02-23-04, 11:56 PM
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I also see the co standing for combined. In other words co-generation simply defines the production of two energy sources - electricity and heat - from a single (usually a fossil) fuel source. Although I'm no expert on the subject I found many articles on the web that define it as such and such a definition makes sense to me. The order in which they come should not really be relevant.

I'd be interested to find out resercon's sources for the definition. Perhaps you can give us some references to articles or other sources that define co-generation in the way that you have defined it - ie basically saying that the electricity must come from the waste heat heat.

The last section of resercon's post contradicts my first post that started this thread. Based on your definition the boilers I have described are actually co-generation engines. You say these are not econnomically viable. Yet the article I read which started this whole discussion shows that these boilers are being installed for real in Europe and are economically viable.
 
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Old 02-25-04, 01:58 AM
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The idea of using waste heat to generate electricity is a good one. They have been doing that on large ships for years. Hot stack gasses from the diesel propulsion engines are run through the tubes of a boiler to produce steam. The steam is them used to run a turbine generator. You get a double benefit. First some of the energy that used to go up the stack and out to the atmosphere is used to produce energy. Secondly, the load is taken off the diesel generators that run on much more expensive fuel. The large diesel propulsion engines would typically burn bunker C which is about half the price of regular diesel fuel.

I would say that a regular high efficiency furnace wouldn't discharge enough waste heat to make recovery worthwhile. I would be surprised to see even 1KW going out the stack of a typical home furnace. The ones I've seen discharge through a PVC pipe. There isn't much heat energy left to make use of. On a less efficient furnace, like mine, you would have a lot more heat that you could recover, however, the cost of the equipment necessary to generate electricity (Sterling engine) would be more than what it would take to upgrade an old furnace to a high efficiency one. Perhaps the story would be far different for the heating plant of a larger building though.

The sterling engine is an external combustion engine that's been around a long time. It's biggest drawback in past years has been it's low thermal efficiency. Perhaps things are different today. The waste heat is energy you paid for but were previously thowing away, that kinda makes it free. Using that energy isn't free though.

Upon further reflection, perhaps you can't get the real high efficiency from an oil burning furnace. I forgot where I was at.
 

Last edited by jughead; 02-25-04 at 02:26 AM.
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Old 02-25-04, 11:55 AM
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Based on the article I read which started this thread I also came to the conclusion that it is not a high efficiency boiler. It is probably a convetional boiler which instead of extracting the heat from the flue gases to improve efficiency uses it to run the stirling engine.

The article (and also the manufacturer's data on the web) suggests that this unit in question is a boiler - not a furnace. However, the same principle could also be applied to a furnace.

As for oil - the boilers I was referencing actually run on NG - not oil. I originally posted the thread under "Heating - Gas" and someone moved it into this topic. Sorry for the confusion but we are talking gas as opposed to oil here.
 
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