Off-grid business operations, silencing experiments

[ToddT]

Hi, I've had a Changfa style S1100/12kw for a couple of years but am just starting to incorporate it into my day to day operations. I also picked up a S195/8kw recently that I'll either use at the shop or at the house as emergency power.

For the past three years, I've run my entire small business off the grid using a diesel generator on biodiesel. Currently, I use a 6kw light plant that has a 3 cyl Mitsubishi engine (just under 1 liter in displacement). It's fairly quiet and economical. Now, I want to run the 12kw Chinese diesel and must do something to silence it.

I have a small chemical company (industrial specialty cleaning) and want to do some cogeneration for process heat. Here are some of my plans. I invite any tips and suggestions y'all might share.

Sound deadening: A friend is going to loan me an industrial sound level meter. My plan is to fab a doghouse to go over the generator, adding layers of silencing and testing the loudness at each step. These include:
Automotive exhaust (will check exhaust back pressure to make sure I don't add any more, goal 1.5psi to 3psi max)
Run exhaust through water drum to capture heat
New air breather with larger pleated air filter

Quiet Doghouse:
-plywood box, 3/4"
-add dense foamboard house insulation
-add space between foamboard and plywood to create dead airspace
-coat interior of plywood with industrial undercoating material, keeping dead airspace
-apply indoor/outdoor carpet to interior surface of foam board

The exhaust and coolant will be located outside the doghouse.

I have run heated WVO/biodiesel in my Ford F-250 for over 200,000 miles (over 7 years). I plan on putting together a two tank system for the generator: start on diesel/biodiesel and switch over to heated WVO once up to temp.

Beyond the chemical business (all biodegradable, mostly using sustainable ingredients) I do a lot of biomass work. I have done biomass gasification and am working on ethanol and methane now. Someday I may fuel the diesel generator with woodgas, keeping at least 15% liquid fuel in the mix.

Tips? Suggestions? Warnings? Thanks in advance for any brainstorming y'all might be able to add.

Todd

[rcavictim]

Todd,

I would not use thermally insulating foam board like Styrofoam SMTM as an example.  It will not do much for sound deadening.  Use rockwool panels.  One brand is Roxall, Roxaul(sp?) These panels are extremely effective at trapping acoustical energy and turning it into heat.  If you cannot get the rockwool get compressed slab pink fiberglass wool.  I have that in 2" thickness lining much of the generator room in my shop and it makes a huge difference in the noise level both inside and outside of this room.  It won't melt and deform or catch fire either as styrofoam board can, the exception being it it gets fuel or oil sprayed on it.  In that case it will soak the fuel like a sponge and become flamable the same way a wick is in a kerosene lantern..

[playdiesel]

I am not into co-gen but you have two other sources of noise besides the exhaust. You need to work with the intake noise as much as the exhaust on a Chinese single. There are  intake silencers made for both engines and compressors. My guess is that a compressor unit would be easier to source tha an engine unit of the correct size?  The ignition knock noise is heavy on my DI 1115, REAL heavy, an IDI will be much quiter. Probably goes without saying but you will need to use all that heat stored when you enclose the engine in a hut, cant just vent it ya know? 

[Tom Reed]

Here's the intake silencer I'm planning to use on the s195 http://www.ecompressedair.com/filtration/filter-assemblies/air-intake-filter-assemblies/solberg-fs-30p-200-inlet-air-filter-assembly.aspx

I've built a lot of generator enclosures and found 2" rigid fiberglass insulation to work very well for sound deadening.

[ToddT]

Thanks for the great suggestions. I've been thinking about the intake noise. Here's the breather I bought. My original was damaged so I got this one from Surpluscenter.com: https://www.surpluscenter.com/item.asp?item=28-1711-A&catname=engines

I wasn't planning on using "styrofoam" type insulation board. At Home Depot I found some that seemed much denser. However, I can see the merits in using a fiberglass panel.

With the radiator and the exhaust located outside the doghouse, how hot do y'all think it will get in the doghouse? Maybe I should paint it white to reflect as much as possible.

[dieselgman]

You will no doubt have to also provide for ventilation... Just how much? Be sure to instrument that engine and monitor it carefully for water temps, if they rise too high, you might have to open things up and or provide forced air cooling.

dieselgman

[ToddT]

Planning on oil pressure, oil temp, water temp, hour meter and hz/volt meter. By the way, how do you have an hour meter without a sparkplug? Just 12v off key? In that case, would need a three position key switch: off, on, start (momentary on). Options?

[mbryner]

Hi ToddT,

Welcome.   I don't know about the intake silencer you got from Surplus Center, but I use a Solberg silencer like Tom suggested on my Listeroid and it works great.   

For an hour meter, you can get hour meters that run off 120 VAC.   As soon as the gen head is producing power the hour meter runs.   That's how I keep track on my 6/1.

Marcus

[rcavictim]

Hi ToddT,

Welcome.   I don't know about the intake silencer you got from Surplus Center, but I use a Solberg silencer like Tom suggested on my Listeroid and it works great.   

For an hour meter, you can get hour meters that run off 120 VAC.   As soon as the gen head is producing power the hour meter runs.   That's how I keep track on my 6/1.

Marcus

You have to be careful about what type of 120 VAC chronometer you use.  One that has a built in DC power supply and uses a quartz x-tal timebase internally will be OK.  One that assumes the frequency of the provided 120 volts is 60 Hz to be accurate will be problematic for obvious reasons to those of us that aren't too picky about the frequency of the power we make if the loads don't care.  I picked up a couple of DC powered units from Princess Auto and plan to run them from the 120 volt AC generated output as you suggest through a DC power supply like a wall wort.  That will make accurate accounting of actual hours regardless of generator speed and frequency.

[mbryner]

That's logical.   I stopped running at 450 about 1 year ago, now only at 60-65 Hz so it should be relatively accurate.   Just throwing it out there as an option if you don't have an alternator but you do have a ST head.   Didn't know about the difference between the DC & AC hour meters, though.   Thanks.

[BruceM]

There are some lithium battery self powered engine hours units that sense vibration for counting engine time.  I use one of these since I sometimes run just the air compressor.  If only I could remember the brand name?!

[rcavictim]

Further to my discussion about DC hour meters.  In the case of my VW diesel powered plant I have a 12 volt starting battery and the injection pump required 12 VDC applied to turn it ON.  I plan to merely connect the DC hour meter to the ON-OFF fuel control solenoid port on the IP.  I could go a step further and put a spst 120 vac coil relay in there so that the relay would have to be pulled in for contact closure from the spinning alternator.  The relay contacts would enable the 12 VDC to the hour meter.  No actual engine spinning even though the IP was still activated would not be counted as engine running hours.

[KeithO]

As far as sound insulation goes , being a tight git, I just built a wooden frame and clad it with multiple layers of heavy old rubber conveyor belt.
Considering that an air cooled Ruston is a noisy old beast I'm relatively pleased with it.

A piece with a lace join makes a nice door hinge too

Cheers
Keith