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Author Topic: DIY biomass fueled CoGen system.  (Read 31760 times)
Dolph1983
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« on: April 25, 2011, 10:43:05 PM »

Hi All,

First post here, so greetings from the north west Smiley hope you're all well.

I'm building a CHP based on biomass boiler and butane as the Organic working fluid.

I had the idea about 8 months ago after throwing my teddy over another extortionate leccy bill. I decided i was going to build a system that would would eventually get me the food off the grid. After some research i found out it was the Organic Rankine Cycle i had been visualising and that plenty of people had done it before Roll Eyes. So to save myself a lot of time and money i found a thesis on the web (to make sure i was on the right sort of track) and got the ball rolling.

The project is intended to be Cheap and easy to be sustainably built using almost 100% recycled parts and materials. I have so far built a prototype (very cheap, very basic) boiler out of gas bottles to store loads of heat in the accumulator tank. The hot water (later glycol) will be pumped through plate heat exchangers to dump energy into the butane circuit.

So far i've used bits of copper i had lying around and thats why the boiler has a micro bore coil fitted at the moment. I will later fit a large bore coil but for now the boiler is not a priority. The actual rankine circuit is the main effort now.

So, If anybody knows of a good source to buy cheap used plate heat exchangers i would very much appreciate being let in on it. Wink So far i have got 6 plates out of combi boilers but i will need loads more, bigger the better.

Anyway, here is a link to my youtube channel and vid's:

http://www.youtube.com/user/DoLpH1983?feature=mhum

questions and comments encouraged


peace.

Dolph



« Last Edit: July 21, 2011, 12:54:35 AM by Ivan » Logged

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Baz
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« Reply #1 on: April 26, 2011, 12:05:36 AM »

Kind of reminds me of Naptha engines  tomatosplat

Linking to your sales site on your first post is mmmmm slightly dubious,  police  but I don't think many of our readers are that gullible  wackoteapot . Interesting to run a turbine at below 100C but I think if I were going that far to avoid highish temps for steam I'd go for a Davey Safety Engine since the thing is going to need full supervision anyway.
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Dolph1983
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« Reply #2 on: April 26, 2011, 11:53:34 AM »

I'm very sorry if i have upset you Baz (or anyone else), i'm just here to learn like everyone else.

Not sure what a Naptha Engine is Baz but i'll go and have a google.

The link i posted previously is to my channel, on my channel you will find lots of information which will shows you how to build the BioGen. I have provided frequent updates on the project in the form of videos and they are all in the uploads section. If you so wish you may then purchase a copy of the manual to support further development in the project. My BioGen website is simply intended to give those people who are interested and would like to help an opportunity to do so. I will not be making profit from selling a few manuals at 3.99 mate, but it will help. Kiss

The website is a place for people to acknowledge that building projects ain't cheap, so if they are interested in a project and would like to benefit from a project then maybe they could get involved in the project. Smiley I hope more people have a go at a website of their own because i will (and have) bought manuals to projects i follow, it shows some respect for the amount of time and effort that person has put into their project instead of just expecting all their hard grafted for information for free.

I don't think our readers are gullible at all mate, that's why i'm posting here. I'm posting my idea in the relevant thread and hoping for intelligent people who share a similar interest to get involved or to inspire people to have a go.

Baz, the BioGen boiler in the video has got water inside. This will be replaced with Glycol so that i can run a higher temperature, prob around 120 degrees. But for now it is not worth spending my cash on glycol when 80 degrees will be enough to prove the concept.

The turbine is a scroll expander, they cope well will low rpm and low pressure high flow rates.

Could'nt find any info on the Davey Safety Engine Baz, i'm hoping you could post a link please?

My BioGen boiler is a prototype only, there will be improvements as materials become available, but the nature of the project is to build my system using recycled parts as and when they become available. That means i don't just go out and buy parts new because that is not sustainable. I'd love to come across a 3/4" stainless steel coil, but it ain't happened yet Cry

As for the system needing constant supervision, then yes, until i have a working, leak free prototype organic rankine circuit using BUTANE!! i will not be firing the boiler at the same time. That is why there is a buffer (accumulator tank) attached to the boiler, it stores the energy so that it can then be used without the boiler firing in an alternating mode of operation, like this: Fire Boiler, Boiler Burns out, Use Hot water stored to generate electricity and then re fire the boiler when the water has gone cold. Each module is isolated from the other while testing.

Once i have completed the Electric Generation Module and i'm satisfied it is safe (leak free) i will run the two (Boiler and Electric Generation) together without any worry.

There is of course the possibility of using HFC 245fa as the working fluid in the turbine, this is non flammable, but again this is not available to me while i'm prototyping because i don't hold an F-Gas qualification. 245fa will come latter.

FIRST I MUST PROVE THE CONCEPT (using what is available ie, Butane). Smiley

Dolph







« Last Edit: April 26, 2011, 11:58:01 AM by Dolph1983 » Logged

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Dolph1983
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« Reply #3 on: April 27, 2011, 11:39:07 AM »

Hi,

I'm posting a link to a thesis i used to help me design my system.  It is good reading for anybody who wants to know more about the Organic Rankine Cycle and the use of scroll expanders as turbines.

http://organicrankine.com/orc_documents/scroll_non_auto/TFE_SQ010607.pdf

Enjoy Smiley
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Dolph1983
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« Reply #4 on: May 03, 2011, 09:10:16 PM »

Found another very good website covering organic rankine cycle.

Lots of previous studies have been carried out and documentation is available via this site.

http://organicrankine.com/?page=orc_home Smiley

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Ivan
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« Reply #5 on: May 13, 2011, 03:27:02 AM »

How are you recycling the working fluid (butane)? The one drawback of small-scale rankine engines is that the power required to recycle the fluid is often as great as the power produced by the system, once you've taken into account all the losses in the power-generation stage.
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Dolph1983
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« Reply #6 on: July 20, 2011, 09:59:42 PM »

Ivan, very sorry i did'nt reply but i did'nt realise there was an unanswered post till today! i usually get email notification of new posts but for some reason i hav'nt got one for your post.

Mahoosive Apologies for the late reply but better late than never Wink

I intend to initially use butane as my refrigerant because it is easy to find and recycle half full bottles at my local scrap yard. 

I will be recycling/condensing the working fluid using a plate heat exchanger as the condenser which will hopefully provide enough cooling to condense the butane vapour back to liquid.  the energy/heat that is transferred during this process from the butane to the cooling water will be recycled (recuperated) into the boiler circuit once there is a temperature differential.

This method will require quite a large tank to hold enough cooling water, possibly a 1000 litre tank such as:

http://www.ebay.co.uk/itm/1000-LITRE-STORAGE-CONTAINER-WATER-TANK-RG22-5JA-/180696695219?pt=UK_BOI_FarmingEquipment_RL&hash=item2a125cc1b3#ht_500wt_920

So, recycled biomass is burned to heat the boiler heat transfer fluid (glycol or water) which is stored in a buffer vessel, this fluid then passes through the plates to transfer heat into the butane causing it to vapourise. once work is extracted in the turbine a different plate condenses the butane and dumps the heat into a separate vessel (condensing water tank).  So hopefully i wont be losing too much energy via heat loss, i will be storing it in another part of the system.  Once a temperature differential between the boiler buffer tank and the condensing water tank is detected the glycol flows through a coil in the condensing tank to scavenge (recuperate) the heat back into the glycol.  This would most likely happen over night while the boiler is not firing.  If the boiler buffer and the condenser tank are of equal temperature then the condenser tank would dump its heat via a radiator circuit into another useful application such as central heating (domestic hot water cylinder or heating a greenhouse or swimming pool) until it is fully cooled.

Like you said i want to avoid a situation where i am using all the power generated in the turbine to condense the fluid, the above method is bulky but it will use convection currents and large surface areas to condense the working fluid which requires no power rather than using power in something like a fan assisted condenser.

Of course if you've got a better idea i'm all ears

Thanks for your interest Ivan.



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Ivan
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« Reply #7 on: July 21, 2011, 12:59:46 AM »

It wasn't the cooling that I was asking about, but how you get the cooled liquid back to the area where it will be heated again. You'll need a pump of some sort (or a series of powered valves). Without this, the boiling liquid won't the boiling liquid prevent to much pressure for the low-pressure condensed liquid to recirculate?
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Dolph1983
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« Reply #8 on: July 21, 2011, 11:58:01 AM »

Hi Ivan,

I must have misunderstood what you were asking, sorry.

If you are asking how the liquid will be recirculated then please watch the videos on my youtube channel as it is covered there. You will find the link in the 1st post of this thread.

The videos explain how i will use a pump to recirculate the fluid (butane).

For the prototype i will try to keep costs down and utilise recycled parts: at the moment i have a 12v pump (10watts) which will deliver 8 l/p/m.  I'm going to try a very small bore capillary line to try to equalise the pressure between the vapouriser and the reservoir (as much as i can) so that the pump does not have to overcome a huge pressure differential between vapouriser and reservoir.

If that does'nt work the alternative would be to use 2 port motorised valve and a pump in an alternating fashion to fill the vapouriser.  This is less desirable as the valve will require extra electrical current and cost a lot of bunsen.

For the purposes of the prototype i just want to get it operating, i'm not bothered how efficient it is, i just want to prove that it will work. Once i have a working prototype i can then get help developing it.


Cheers,

Dolph
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Ivan
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« Reply #9 on: July 26, 2011, 01:42:49 AM »

For low power systems, the recirculation pump saps a very large percentage of the generated power. I don't think the pressure-balancing capillary tube will make any difference. By the time it's large enough to have any effect, it will be providing a route for gases to  bypass the turbine.

Using a pair of 2-way valves would be a good way to allow a low power pump to recirculate the liquid without having to cope with the pressure differences. But again, the power consumption of the 2-way valves will be significant unless the system produces a decent amount of power.

I think it could be quite difficult to get it to work at all, but certainly would be very interesting if you could get it to work. There is an american company developing a rankine cycle engine using solenoid valves to get over the high pressure difference pump requirement. I can't remember their name (as soon as they got a demo unit going, they started advertising for investors rather than developing their product). I think I posted a link here in this section of the forum somewhere, if you've got time to look for it.

 
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A.L.
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« Reply #10 on: July 26, 2011, 10:10:44 AM »

hello Dolph,

this is Ivans link matteranenergy.us/Joe%20Sixpack's%20Technology%20Page.html or watch 3/4 through the video on the home page
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Dolph1983
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« Reply #11 on: July 26, 2011, 06:04:21 PM »

A.I thanks for the link.  I had seen an older version of that animation somewhere before so good to finally watch the rest of the video.


Ivan,

i'd thought about solenoid valves using bypasses to the reservoirs and gravity feed to supply the vapouriser but when i looked at the cost of the 12v solenoid valves it weasel peed on the bonfire somewhat!  I've got lots of ideas i'd like to test, but unfortunately they will have to wait till i have a some money for development.  I'm trying to keep it fairly plain vanilla just to get people interested, then the really experimental stuff can begin.  At the moment i'm willing to sacrifice say 10% of the vapouriser flow at the cost of efficiency: if it helps me run a smaller pump therefore keeping cost down.


Work on my BioGen power generation module is progressing well (in my opinion!), hopefully by the end of the week i will have a new video and a working system to demonstrate (just waiting for a few more parts off Ebay to come through), if not i will keep saving for bigger heat exchangers and a smaller turbine and at least i will have eliminated one of my designs so i can move to the next. Think i'll take some photo's of what i've built even if it does'nt work and throw them to the wolves on here, see what good comes out of it.

Dolph.

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Ivan
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« Reply #12 on: July 27, 2011, 01:02:37 AM »

I think it will be difficult to get a small-scale unit to produce more power than it will consume especially with a pump.

You can buy LPG solenoid valves from autogas equipment suppliers. Last time I had anything to do with them, the cost was 16 each and they'll cope with quite high pressures.
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Dolph1983
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« Reply #13 on: July 27, 2011, 10:52:34 AM »

Nice one Ivan, i had a look and found a few options for 12v solenoid valves at around 15 quid mark. They are micro bore but still may be very useful. My electrical knowledge isn't up to much but: i am thinking if i use a double pole isolator these valves won't draw current when not in use?

The ones i had looked at were 15mm or 22mm bore, 0 - 10 bar, upto +160 degrees Celsius costing anything up to 500 squid each!

Thanks
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Ivan
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« Reply #14 on: July 28, 2011, 02:03:31 AM »

The LPG solenoids consume 5-8W depending on manufacturer, and are designed for working pressures of 150psi. Connections are usually 6mm copper pipe.

Keep us informed of progress.
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