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Genset 100kw ENBA NG to Propane Questions


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  #1  
Old 12-09-2017, 08:41:47 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Genset 100kw ENBA NG to Propane Questions

Hello all,

I was given an Onan 100kw ENBA and 1K amp switcher (nice gift right! especially considering it has about 300hrs run time) but its factory natural gas. I purchased the Impco Model E gassifier/reg and Impco VFF30 (flow back stop) to convert to propane as we have no NG availability in my area.

NOTE- THis is the ENBA with the turbocharged Ford 460 and NOT the V10. The V10 lists fuel as NG/Propane, the 460 is NG.




Here is a pic of the components pre turbo. There is a 'Maxitrol' reg and what I am assuming is the mixer going into the turbo inlet on the compressor.

Questions:

-Do I remove the Maxitrol reg and connect the Model E gas output into the mixer or should leave (or would it matter) if I left this reg and connected the Impco into this reg? I almost like the idea of leaving it IF it doesnt hurt anything as it would be cool to have a 'NG/Propane ready' generator.


-Is there anything else I need to do to be able to safely run this engine with propane (jetting, ignition timing or other)?

-Do I need a post regulator pressure gauge or secondary regulation?

Thanks for any help on this matter!

~JH
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Old 12-10-2017, 12:18:15 AM
ulgydog56 ulgydog56 is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

maxietrol is a pressure regulater,nat gas runs at 3.3 to3.8 in equip normally in usa,check equipment,ratings,lp gas normally runs at 10 to 12 ins of water collium, regs are adjustable,but from 1 gas to another u normally change regulators or springs and possably jet or orface size,should be a kit for it,make sure its got to be right......
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Old 12-10-2017, 03:59:43 AM
armandh armandh is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

this is a total guess but
once the pressure is reduced to the inlet of the demand regulator
with a typical tank regulator of sufficient size

if the arrow in the picture is pointing to an adjustment screw with jam nut
it is likely the mixture to be adjusted less for the higher BTU fuel
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Old 12-10-2017, 04:13:20 AM
AngrySailor AngrySailor is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

I wonder how long this would run on a BBQ tank

What a gift! Do you have a use for all that power?
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Old 12-10-2017, 04:30:42 AM
armandh armandh is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

depends on the load

had a 71 Lincoln with that 460 motor
it had a GM style starter & solenoid
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Old 12-10-2017, 10:23:31 AM
pegasuspinto pegasuspinto is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

The device labeled "maxtrol" in the picture is the demand regulator and that is the component that will need changed.

On dual fuel units, there will be a T between the demand regulator and the mixer and there will be a second demand regulator, one for each fuel, and the inlet solenoids select between the two.

Natural gas gensets, especially this big, use pressures more in the 11-14 inches range.

I am a little puzzled because the demand regulator is normally installed with the 'snout' straight up or straight down, because it's calibrated with a weight inside. Sometimes all you need to do to convert them is to flip it over and remove the spring.
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Old 12-10-2017, 11:26:00 AM
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Default Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by AngrySailor View Post
I wonder how long this would run on a BBQ tank
Somewhere around 14 GPH Propane at full load and (guessing) 6 GPH at no load. With 3 gallons in your BBQ tank, that's 30 minutes at no load and 13 minutes at full load. Of course the BBQ tank wouldn't support this draw rate...
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Old 12-10-2017, 11:51:14 AM
JT240Z JT240Z is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

That "gift" is going to cost you a ton to operate.
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Old 12-10-2017, 06:35:33 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

Yes 'Big Pig' will use a fair clip of fuel. My calcs are a little better than the above estimation of GPH burn but do understand this is a big piece. My demand range for my house would realistically be in the 8K (lowest without heat and the water heaters cycled off) to 25-35K (highest). As can be heard in the video the sound is the WIND in our area (Columbia River Gorge). Its not uncommon for us to loose power for a few hours (often) or days (rare but it happens) a few times each winter. Ironically our power was out during the video and the second time in the last few days. I estimate the generator will be running at 10-20% load and we will only use it during awake-occupied times.

-My plan is to use 4x 100# tanks (ganged) and have 6x or so 30# 'forklift LP' tanks as backup.



Quote:
Originally Posted by pegasuspinto View Post
The device labeled "maxtrol" in the picture is the demand regulator and that is the component that will need changed.



Natural gas gensets, especially this big, use pressures more in the 11-14 inches range.

I am a little puzzled because the demand regulator is normally installed with the 'snout' straight up or straight down, because it's calibrated with a weight inside. Sometimes all you need to do to convert them is to flip it over and remove the spring.
I found this from Maxitrol for this 'LMP 53' regarding using this with propane:

Remove the cap on the end of the cone & notice the white plastic threaded adjuster that compresses the spring.
Remove the adjuster with a screwdriver & take out the spring.
Turn in the adjuster approx 2/3 - 3/4 of the way down the threaded cone so there is room to store the spring above the adjuster.
Replace the threaded cap at the end of the cone.
The spring is now just in storage and NOT used to regulate pressure, so now instead the regulator controls volume or flow, based on engine demand created by vacuum from the engine.
The device must now be positioned with the cone pointed DOWN, so that the internal "valve" will drop down and shut off the fuel until engine demand / vacuum calls for it.



Got the big pig to run!

I didnt point the Maxitrol down during test but it is now. I also have not connected the coolant passage lines to the gasifier or connect the back purge device. I just wanted to see if it fired and ran ok.

https://www.facebook.com/jonny.hotnu...3624522303418/


I was actually shocked how fast it started after not being run since 2003.
It fired in a split second and was running very smoothly.

Now the big question:

Now that shes running, how can I tell if its running healthy? Meaning if this was a gas engine I could check AFR/EGT or read plugs or listen to any knock to get an idea of engine health.
Some have mentioned that I may need to adjust mixture/jetting but how can you tell if any changes made are beneficial/detrimental?

Sorry if this is a bone headed question; this propane stuff is WAY out of my wheelhouse.

Oh....AND BIG PIG LIVES! LOL

~JH
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Old 12-10-2017, 06:48:47 PM
Wayne 440 Wayne 440 is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

I claim no expertise, but FYI- years ago my employer installed a 30kW Kohler and used 4 x 100 lb tanks as a fuel supply. The actual load was about 10kW, and the tanks would not vaporize an adequate volume below about 40 degrees.

My advice- consider liquid feed and a much larger tank arrangement.
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Old 12-10-2017, 07:04:00 PM
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Default Re: Genset 100kw ENBA NG to propane questions.

Jonny We don't have stupid questions on this site. If you knew the answer you would't be asking. So ask any question you need to. That is how you learn.
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Old 12-10-2017, 07:56:43 PM
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Default Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by Jonny Hotnuts View Post
...My calcs are a little better than the above estimation of GPH burn but do understand this is a big piece...
What is your estimate on propane usage, and how did you get it?

I based mine on the Onan gaseous fuel manual, interpolating between other similar-sized sets.
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Old 12-10-2017, 08:05:44 PM
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Default Re: Genset 100kw ENBA NG to propane questions.

The "Maxitrol" regulator can be used as a pressure regulator or as a "zero" regulator or "demand" regulator. It's counter-balanced with a spring on the underside of the diaphragm. (Under the cover with the four screws) which converts it to a "zero" regulator
The fuel mixture adjustment is the lock-nutted screw on the mixer.
Adjust the demand reg with line pressure applied, and adjust to zero flow.
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Old 12-10-2017, 08:25:26 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by Wayne 440 View Post
I claim no expertise, but FYI- years ago my employer installed a 30kW Kohler and used 4 x 100 lb tanks as a fuel supply. The actual load was about 10kW, and the tanks would not vaporize an adequate volume below about 40 degrees.

My advice- consider liquid feed and a much larger tank arrangement.

Wayne,

This is a liquid propane feed system with thermal vaporizer. I havent hooked up the coolant lines (what heats the vaporizer) yet but only intended to test run for a few seconds.

-In the future the generator and tanks will be housed in an insulated 'generator house' that will have some level of heating. The generator and tanks should never get very cold.


Quote:
Jonny We don't have stupid questions on this site. If you knew the answer you would't be asking. So ask any question you need to. That is how you learn.
THanks Billy but Ill bet before its all said and done you may rethink this stance after the crap I can come up with. LOL

~JH

Quote:
Originally Posted by Jim McIntyre View Post
What is your estimate on propane usage, and how did you get it?

I based mine on the Onan gaseous fuel manual, interpolating between other similar-sized sets.


I calced it by my estimated 'high side average' of my usage @ 20K watts, needing ~40hp and consuming 400,000btu per hour. A 'bbq' tank (4.7g) has about 442,000 btu. This would mean at a 20% load the generator would run about an hour, maybe a little more.

-Am I way off?

~JH
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Old 12-10-2017, 09:24:16 PM
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Default Re: Genset 100kw ENBA NG to propane questions.

^ I don't know. I have decent confidence in my 14 GPH full load estimate. But, this being a turbocharged set, I'm not too sure about the no-load estimate. My estimate above might have been pessimistic. I don't see the consumption spec in any of the ENBA manuals...
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Old 12-10-2017, 09:40:32 PM
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Default Re: Genset 100kw ENBA NG to propane questions.

Jonny I have been helping people since 1975. There have been more than a few that made me want to. Beat my head on the wall. But I keep trying. Always will. Besides just when you think you have heard it all. Some one new comes along.
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Old 12-10-2017, 09:45:24 PM
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Smile Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by ulgydog56 View Post
maxietrol is a pressure regulater,nat gas runs at 3.3 to3.8 in equip normally in usa,check equipment,ratings,lp gas normally runs at 10 to 12 ins of water collium, regs are adjustable,but from 1 gas to another u normally change regulators or springs and possably jet or orface size,should be a kit for it,make sure its got to be right......
lp bbq tanks won,t work,set at diff pressure than 100,250,500#tanks,u would be changen tanks like a madman with that460 lol
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Old 12-11-2017, 02:21:28 AM
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Default Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by Jonny Hotnuts View Post
....Now that shes running, how can I tell if its running healthy? Meaning if this was a gas engine I could check AFR/EGT or read plugs or listen to any knock to get an idea of engine health.
Some have mentioned that I may need to adjust mixture/jetting but how can you tell if any changes made are beneficial/detrimental?....
Are you saying you have access to an AFR meter? If so, it should have multiple fuels on it. Select LP and give it a check. Unfortunately, this check needs to be done at or very near full load. At full load, you'd want a lambda around .95~.96 for propane, or an LPG AFR of around 14.90~15.08. Adjust fueling with the power valve (see below.)

Seat of the pants method, again with full load, would be to turn the "power valve" adjustment on or near the mixer body, to "leaner", slowly, just until you hear the engine miss or falter, then slowly go back towards rich until smooth. You can also hook up a vacuum gauge while doing this and observe for the highest vacuum reading when slowly going back towards "rich." You just have to play with it a little by this method, until you're happy with it. If you shut it down hot, and do a rapid restart and it fires right off without backfiring or lighting some gas off in the muffler, you're close enough.

Make sure the plugs are set at 0.035", and timing is at 32 BTDC @ 1800 rpms.
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Old 12-11-2017, 03:15:43 AM
AngrySailor AngrySailor is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

You can use any heated o2 sensor as an AFR tester. just place it in the exhaust (with no leaks and well away from the end of the tail pipe to prevent reversion readings) and read it with a good volt meter. Check the sensor specs but 1.5v & lambda rings a bell but it's been a while since I did this.

EDIT: some quick research shows that output is 0-1v, increasing as oxygen decreases (richer mixture) lambda @ ~0.45v.

Last edited by AngrySailor; 12-11-2017 at 04:23:22 AM. Reason: Correction
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Old 12-11-2017, 12:46:50 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Wow guys, thanks for the info. Ill need to go over it all once I get home from dumb work.

-Quick question:

Will the OEM NG setup run leaner or richer if these settings are maintained and propane is used?

Lets just say I have some bad experiences in the past with lean conditions on other stuff. While the experiences are too difficult to speak of, Ill bet you can understand where Im going!

I dont mind if its fatter, I just dont want to be on the other side of the coin!

Thanks again, Im a little overwhelmed with the good info on this odd project.

~JH
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