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Powering Diesel Gensets


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  #1  
Old 03-10-2017, 03:45:52 PM
Utah Onan Utah Onan is offline
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Default Powering Diesel Gensets

Question to all the Diesel Genset owners/users/maintainers...
Have any of you out there considered bi-fuel for your generator? Meaning that your generator would operate on potentially 60% less diesel fuel while using natural gas. Or another way to look at it would be that the generator would run on 40% diesel fuel & 60% natural gas.
Any insight? Comments?

thanks in advance

Utah

---------- Post added at 12:45:52 PM ---------- Previous post was at 12:43:56 PM ----------

....also see this https://www.youtube.com/watch?v=IOJgv0GqyYM
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  #2  
Old 03-10-2017, 04:31:07 PM
Kevin K Kevin K is offline
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Default Re: Powering Diesel Gensets

In a word: NO! In two words: Absolutely NO! My generator can use on road diesel, off road diesel, or #2 fuel oil. I want it to be ready to run when I need it. For an emergency generator, the fuel cost is a small part of the expense. I'll leave the diesel/natural gas and waste vegetable oil to others who want to spend a lot of time, effort, and money trying to save a few dollars.
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Old 03-10-2017, 04:45:31 PM
Vanman Vanman is offline
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Default Re: Powering Diesel Gensets

Contrarily, I would maintain that the fuel cost of an emergency generator can quickly become the most expensive part of the installation, especially when a set that is too large is installed, and even worse if it is used to supply electric heat, while ~80% of the heat from the fuel burned is thrown away. Fact is, the days of cheap fuel are long, LONG gone.

That said, it's my understanding that diesels can run very well on gaseous fuels so long as the mixture is kept sufficiently lean so as to not auto ignite, and thus with the diesel injection serving as both pilot fuel and ignition timing.

I don't know how you would accomplish this in an engine that is not designed for it though. I can envision fairly sophisticated controls handling it, but contrary to modern belief, simple really is better.

You'd need to have a way to have the governor control the gas flow instead of the diesel injection rate, while leaving the latter at some small, presumably fixed amount, such as that at idle. If the load comes off, it would need to cut the gas supply, and revert to straight diesel operation, with the governor controlling as normally. Interesting, for sure.

I'm sure some engines would be much easier to modify than others, and some, ie Detroits, must never ingest fuel into the intake as it can explode in the airbox since the cylinder is full of hot exhaust gasses- and very likely sparks- when the piston uncovers the intake ports.
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Old 03-10-2017, 04:52:44 PM
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Elden DuRand Elden DuRand is offline
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Default Re: Powering Diesel Gensets

I've seen some of the larger Fairbanks-Morse Diesel engines that were modified to run using natural gas as the main fuel. The Diesel injection pumps were, I think, set to a fixed minimum delivery, acting only as an ignition source.

It is my understanding that natural gas or propane have a high enough ignition temperature that they won't ignite even at Diesel compression ratios.

Of course, the governor must control the volume of gaseous fuel mixed into the intake air to be able to manage engine RPM and power output.

I experimented using propane from an unlit torch into the intake of my Homebrew Hvid and it behaved itself nicely. If I wanted to go to the trouble of converting it, it would be relatively easy.
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Old 03-10-2017, 05:03:45 PM
yellowlister yellowlister is offline
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Default Re: Powering Diesel Gensets

Why not just have a spark ignition engine and use natural gas on them.. what's the point of useing gas on a diesel.. is it really going to be cost effective to get it to run right and not shorten the engine life?

Probably much cheaper to leave it alone and buy solar panels in the long run
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Old 03-10-2017, 05:04:14 PM
Birken Vogt Birken Vogt is offline
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Default Re: Powering Diesel Gensets

With this sort of setup I wonder if you have to throttle the intake air as well or if simply mixing lean gaseous fuel into wide open air is going to get it to all burn.
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Old 03-10-2017, 05:23:13 PM
Dale Russell Dale Russell is offline
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Default Re: Powering Diesel Gensets

Having worked in a Municipal Power Plant with LARGE ENGINES that used this sort of system, this is not for the average Joe to play with. We ran 6% Pilot Fuel, (Diesel) for Ignition & 94% Natural Gas and both were controlled very close. The engine would have to be Engineered from the factory to be SAFE.

My $.02 worth!
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Old 03-10-2017, 05:36:36 PM
gnucklehead gnucklehead is offline
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Default Re: Powering Diesel Gensets

My solution to this is to have multiple generators.. What happens when your NatGas doesn't work? I would use Biodiesel, but not putting veggie oil in my Onan unless it's the last resort, I have an IDI chinese diesel for that I even have gasoline sets
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Old 03-10-2017, 05:37:53 PM
len k len k is offline
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Default Re: Powering Diesel Gensets

Interesting idea if you could do it. But let me ask why not just use a nat gas engine? Is a diesel running on nat gas more efficient because of higher compression? If it is then why not machine head to accept a spark plug and flow nat gas thru the "carb"?
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Old 03-10-2017, 06:05:18 PM
pegasuspinto pegasuspinto is offline
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Default Re: Powering Diesel Gensets

Bi fuel engines are not uncommon. The most basic systems just add nat gas in a fixed relation to load. If the natural gas can't keep up or just quits, the diesel governor takes over basically instantly. the diesel side is basically un modified.

i don't see why you couldn't do this with a ardunio or something couldn't make this work fine. Just don't run the razors edge running too little diesel, the pros have knock sensors etc to prevent pushing too hard.
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Old 03-10-2017, 06:15:05 PM
Wayne 440 Wayne 440 is offline
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Default Re: Powering Diesel Gensets

Nearly all of my applications are for standby use, so fuel costs are not a large issue. Diesel fuel is cheaper than a hotel room will be. And a large tank of diesel fuel is more reliable than the local natural gas service by a large margin.

I have thought about bi-fuel, but just in the context of a "what if" situation- as in "what if" I end up in a situation where natural gas is plentiful, but diesel isn't.
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Old 03-10-2017, 06:22:55 PM
Gunny Gunny is offline
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Default Re: Powering Diesel Gensets

When I worked for Cummins/Onan, commissioned a few. Not that hard to do, absolutely important to set it up right or you would have a serious problem quick.

They worked quit well for load management but nt so good when assuming a large load.

The idea is that the diesel is the pilot fuel, provides the ignition. Changing the fuel rate of the injection pump works to throttle the engine up and down, same as in a straight diesel engine. Within a range. Drop a large load on it at the edge of this envelope, you might start melting things real fast. Will need some logic to detect knock.

Do NOT try that with propane. That is a recipe for disaster. Like lift the heads right off the block.

For a smaller home standby, no. A larger genset used for load management, yes, can be very cost effective. Also cleans up smoke/emissions on older engines. Yes can work fine on 2 stroke engines also.
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Old 03-10-2017, 07:36:02 PM
soundbos soundbos is offline
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Default Re: Powering Diesel Gensets

We have installed many LPG Bi fuel setups on Irrigator motors The last was a John Deere 250 HP with an Impco setup
They run about 60-70% propane
Engines run quieter and cooler

Butch
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Old 03-10-2017, 07:44:15 PM
yellowlister yellowlister is offline
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Default Re: Powering Diesel Gensets

All of the buses and some city vehicles like trash trucks have been converted from diesel to natural gas here.. but being that the largest natural gas storage is a mountain between here and simi valley fuel costs are super cheap..

Does anyone remember the natural gas leak a year ago in the San Fernando Valley?

But mostly done for emissions reasons.. the cost to convert them was crazy.. something like 30 million just for the city buses and trash trucks
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Old 03-10-2017, 09:10:33 PM
Richard L Richard L is offline
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Thumbs down Re: Powering Diesel Gensets

I have no use for diesel with ethanol , in it . Ethanol is a water magnet, have seen new tractor injection pumps that have rusted shut, sitting over the winter. My injection pump guy says ethanol in diesel is a MONEY MAKER for him. It also will freeze up in the cold weather, and several school bus companies found this out the hard way.
Re diesel/natural gas units. Sold some EMD powered 2 MW units to a project to provide 12 MW prime and then they decided that they wanted them to be set up for natural gas/5% diesel kicker.
The cost of the conversion system, gas supply lines and the install price canceled the order.
The other side of the Ethanol story, is what it really costs to produce a gallon of it and the effect that it has had on the real price of fuel.

Cant get political, its crap.
My $.02 worth.
R
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Old 03-10-2017, 09:39:44 PM
I like oldstuff I like oldstuff is offline
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Default Re: Powering Diesel Gensets

[QUOTE=yellowlister; Does anyone remember the natural gas leak a year ago in the San Fernando Valley?[/QUOTE]

Poof goes a block of San Bruno. Pretty sad as residents were complaining of gas smell for weeks prior.
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Old 03-11-2017, 01:25:06 AM
Vanman Vanman is offline
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Default Re: Powering Diesel Gensets

It seems like, even for standby service, the natural gas burning diesel generator set could be pretty nice. You have the general superiority of the diesel engine. The greater efficiency. But then you also get the lower unit fuel cost of the natural gas, as well as the infinite supply that comes with it. And, you get fuel redundancy! If the natural gas system also fails during the power failure (a very real possibility), your set continues on like nothing happened, now running on your on site diesel fuel supply. I think it would be fantastic!

One could do the same thing with a spark ignition gaseous fueled set, running on natural gas with propane backup. But when the natural gas fails, AND your on site fuel runs out, it would be MUCH easier to source some more diesel than it will be to source propane.

Interestingly, my very first job as an electrician was a building with a (IIRC) 60 kW Onan, running on natural gas with AUTOMATIC propane backup from a tank on the roof. It was pretty sweet! Close the natural gas supply valve to test while the set was running under load, and the engine would surge a little during the brief switch over, then continue to run as normal! Open the valve back up, and the switch back was undetectable.
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Old 03-11-2017, 02:01:36 AM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Powering Diesel Gensets

Quote:
Originally Posted by Vanman View Post
...And, you get fuel redundancy...
Sort of. But when you're out of Diesel fuel, it's lights out...
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Old 03-11-2017, 02:27:22 AM
pegasuspinto pegasuspinto is offline
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Default Re: Powering Diesel Gensets

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Originally Posted by Vanman View Post
One could do the same thing with a spark ignition gaseous fueled set, running on natural gas with propane backup. But when the natural gas fails, AND your on site fuel runs out, it would be MUCH easier to source some more diesel than it will be to source propane.
Not really. On a diesel set, the only real control is over the fuel volume. More fuel=more power. Bleed something into the intake, like natural gas, the diesel pump cuts the fuel to keep the speed constant. You could in theory get by with a hose in the intake and a manual valve. On a LP or even gasoline unit, if you just simply add fuel, it will run rich. You would have to figure out a way to simultaneously throttle back the other fuel to keep the mixture the same. A bit more complex then the diesel.
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Old 03-11-2017, 07:59:44 AM
Mikey NY Mikey NY is offline
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Default Re: Powering Diesel Gensets

I have heard of some people doing hydrogen boosting in cars, to get better fuel mileage. I forget where I read that though. It might be more feasible and user friendly than trying to mix in nat. gas or propane on a genset .
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