Author Topic: Dual Fuel  (Read 5107 times)

carlb23

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Dual Fuel
« on: August 15, 2008, 10:54:34 PM »
I have been playing around with the idea of running my lister on Diesel/natural gas for a while now.  I recently came across a small J&S carburetor (not much of a carburetor) but I was able to make it work pretty well.  While some fine tuning will be in order I can say that by fogging the intake with natural gas through this carb the engine is working well. This carburetor does not have a variable metering device so you only have an adjustment setting for the gas flow and that is it. I removed both the throttle blade and the chock  plates.

I was concerned that the 1" bore would be too restrictive but that doesn't seem to be the case.  I made up an adapter plate to attach it directly to the head. Running on diesel with no adjustments the engine ran the same as with just the pipe and air cleaner through the entire load range.

Starting the engine on diesel with no load i marked a line of the injector pump rack as a reference point.  When i turn on the natural gas the injector pump closes to what would be the required rack setting if the engine were running about 350 rpm I know this because i turned off the natural gas and moved the rack by had to where it had closed when the natural gas was on and my tach red 347rpm.

While i only loaded the engine a 6/1  metro to about 2500 watts the rack only moved slightly above where it would idle at no load. While i have no hard data on fuel consumption or on the amount of natural gas going into the engine right now I suspect that i am probably substituting at least 60% with natural gas.

At one point when it was running at no load if I increased the natural gas a little to much the rack would go too far closed and the engine would start to misfire. I suspect that there was not enough diesel going into the engine to light the natural gas off.

I will post a video in the near future after i get a little further along in my testing.  I think i need to take a fixed amount of diesel and a flow meter to see how much natural gas is really flowing with a constant load and see how well it does.


One thing i wanted to point out is that I did not modify the lister governor in any way I am just fogging natural gas into the intake at a fixed amount and the governor will add additional diesel if the load increases. Since it is easy to adjust the flow of natural gas I will set it for maximum efficiency at around 2,000 watts.  In this way while it will run with a little too much natural gas at no load it is quite happy from 500 watts to 2000 watts while never moving the rack past where it would run at no load on just diesel.

When the natural gas is not turned on the engine runs as it normally did on diesel.
I have a low voltage DC gas valve that I will wire into the generator (using a 24 volt dc power supply) so that no gas can go to the engine unless the generator is actually producing power so if the engine were to brake or stop for some reason the natural gas valve would close. This valve also has a manual on/off valve that will only allow gas to flow if the valve is on and power is applied.  I will use this valve to turn off the gas flow for startup and shutdown of the engine.


Carl

mobile_bob

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Re: Dual Fuel
« Reply #1 on: August 16, 2008, 02:47:04 AM »
Carl:

nice report!

i look forward to some fuel consumtion vs power output test results

isn't it interesting how these engines run in dual fuel mode, opens up several alternate fuel possibilities
doesn't it?

propane, methane, butane, nat gas, producer gas, vaporized alcohol, frog farts, (ok maybe not the last one
unless you raise alot of frogs) :) , hydrogen (for all the H2 fanatics) :)  etc.

that way a guy can run it on whatever fuel is available of lower in cost for the output he is after.

one thing for sure, there should be less emissions? smoke reduction?

there ought to be a competition to see who can successfully run a listeroid on the largest numbers of alternate fuels
reliably while producing useful power.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

carlb23

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Re: Dual Fuel
« Reply #2 on: August 16, 2008, 02:02:35 PM »
I think the most interesting thing i noticed was that i could meter a set amount of natural gas into the intake and let the stock governor work as normal and reduce the use of diesel so much. The way i currently have it setup up surely isn't ideal but at this time i don't have the option of varying the natural gas injection with load. My thoughts are that if I can reduce the amount of diesel used based on a moderate load to near 600 rpm no load conditions even at higher loads i am not introducing much diesel into the engine.  At no load with the engine running the rack in where it would normally be if running on diesel at 350rpm. At moderate load 2kw or so the rack is where it normally is at no load 650 to 700 rpm. I can't imagine  that much diesel is being injected at that setting. I will be working this weekend on hard piping the natural gas to the engine.

I will post an update as progress on this project, but now its time to mow the lawn  :'(


Carl

Jim Mc

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Re: Dual Fuel
« Reply #3 on: August 16, 2008, 02:48:51 PM »
I don't see the purpose of the carb in the setup you describe.   ???

Unless you're using a "fuel controller" (which is really just a sub-atmospheric pressure regulator) on the natural gas line, the same amount of gas will flow, pretty much without regard to the load on the engine, its speed, even whether if it's not running.  In that case, what's the carb doing?  Just a mixing chamber?




carlb23

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Re: Dual Fuel
« Reply #4 on: August 16, 2008, 05:15:26 PM »
I don't see the purpose of the carb in the setup you describe.   ???

Unless you're using a "fuel controller" (which is really just a sub-atmospheric pressure regulator) on the natural gas line, the same amount of gas will flow, pretty much without regard to the load on the engine, its speed, even whether if it's not running.  In that case, what's the carb doing?  Just a mixing chamber?

I am just using the "carb" as a mixing chamber like you said. I set the flow rate at the gas regulator (white rodgers low voltage DC) for a 2kw load with the governor keeping the rack at the no load position (625 rpm or so) as i increase the gas flow the rack closes. When the load decreases the fuel rack closes down to where the engine would only be running at 350
if on diesel only. While modulation the gas flow is preferable this was a simple way to run the engine with a 2kw load and use almost no diesel. I suspect that i could lower the amount of diesel more at 2kw but when the load is dropped off the rack closes too far and the engine starts to miss because there is not enough diesel to start the combustion process.



ronmar

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Re: Dual Fuel
« Reply #5 on: August 16, 2008, 07:21:52 PM »
I don't think you need the carb either with natural gas or propane under pressure.  It sounds like the carb is just restricting airflow.  I would guess you could achieve the same result by just putting the gas hose into the air cleaner or intake elbow that came with the engine. The gas will be drawn in with the intake air stream and will combust just like it is now...   
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xyzer

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Re: Dual Fuel
« Reply #6 on: August 16, 2008, 09:10:07 PM »
I don't think you need the carb either with natural gas or propane under pressure.  It sounds like the carb is just restricting airflow.  I would guess you could achieve the same result by just putting the gas hose into the air cleaner or intake elbow that came with the engine. The gas will be drawn in with the intake air stream and will combust just like it is now...   

Do other(natural propane) gas carburators  have a flashback built in the? Do you need one? Just wondering. Seem like a flowmeter would do the same as the carburator only it would tell you how much you are using....Sounds like fun anyway....only gas I have around here is close to the frog farts ;D
Dave
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carlb23

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Re: Dual Fuel
« Reply #7 on: August 17, 2008, 02:27:23 PM »
This is a carb that i had around so i figured i would give it a try.  The problem is that it only has a butterfly to control air but not fuel delivery.  Fuel deliver is set by an adjustment screw but it does not change with the throttle plate opening and closing.  I removed the throttle plate and set the adjustment screw for the amount of natural gas i wanted to introduce.

I really don't like this carb and i think that using a rotameter / flowmeter after the electric gas valve and then directly into the original listeroid air inlet pipe will be a better way to go.  I am still early on in the experimenting phase but I know for sure that I can reduce the amount of diesel by at least 60%.

When i get a flowmeter inline I will load the engine to say 2k and measure how long it runs on say 4oz of diesel and how much natural gas it uses.

Carl

ronmar

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Re: Dual Fuel
« Reply #8 on: August 17, 2008, 05:01:31 PM »
You should have no problem controlling fuel delivery with either a flow meter(fixed pressure, variable orifice) or a LP regulator(fixed orifice, variable pressure).  The flow control off a gas BBQ immediatly comes to mind. 
PS 6/1 - ST-5.