Natural Gas-Driven Emergency Generator Exhaust

[KLH]

Hi,

Does anyone know the purpose of the conical shaped device located between the generator and the silencer?

Thanks.

 

[ivymike]

not offhand... what's it connected to above? Is it actually exchanging gases with a duct (the way it looks in the picture)?

 

[KLH]

It is not connected to anything. The duct is several feet above the exhaust piping.

What you see at the top is some sort of cap, about the size of a garden hose.

 

[ivymike]

maybe it's an exhaust take-off for a (disconnected) EGR system? do you see any provisions on the inlet side of the engine for connecting similar-size tubes (sized like the plug on top)?

 

[KLH]

I didn't notice. I'll have to check during my next visit.

Thanks for your help!

 

[MiketheEngineer]

Maybe some plumber ran out of pipe and these "just fit"..

 

[rmw]

It looks to me like a crude attempt at a vacuum type jet. But I can't imagine what someone would have wanted to pull into the exhaust stream at this point.

rmw

 

[Compositepro]

It looks like a venturi design. Perhaps intended for mixing air or water into the exhaust to cool it. Something like that might be used for marine applications.

 

[bcs5274]

venturi setup that i have seen used to pull crankcase fumes/pressure and dispose of as to not fume up the building/enclosure it is in

 

[ivymike]

venturis are also used with some inlet air filtration schemes (separators) to dispose of the collected dirt, especially in dusty environments...

but if this thing is supposed to be a venturi, it doesn't look like one that would work very well. I'm not liking the step change in diameter upstream of it, and unless the side tube curves inside the device to get to the throat, it's not getting the suction.

 

[btrueblood]

Which might explain the cap. Somebody built what he thought would be a venturi (for use in one or more of the above schemes), but fubbed it, and the darn thing blew smoke in his face when he fired up the motor. So, he cut the pipe and capped it, and walked away red-faced.

 

[btrueblood]

Another thought, my original one, was that the tap was intended to be upstream of the restriction, and the tapped exhaust was going to be passed through a heat exchanger for a co-gen application (thought that was what the adjacent duct was).

 

[racookpe1978]

I agree with the "home-made/jury-rigger/jerry-rigged/redneck" set of parts (trying) to make a venturi at the end.

The first "step reducer" is actually a spoolpiece hand-made after original de-construction to replace a removed valve or fitting or adapter/tee/pipe section. This removed pipe section would have fit between the first large flange on the right and the same size flange on the venturi inlet.

 

[racookpe1978]

Is the direction of flow from right to left?

Pipe diameters keep getting smaller !!! if start from the right and go left, but you'd want your exhaust to get bigger (or stay the same at least) to improve efficiency of the flow.

Sudden start/stops, changes in diameter for no (now) good reason, sharp bends and decreasing pipe sizes screw up flow big time.

Replace the whole thing, starting at the reducing street elbow at the first bend. Use long radius elbow, as big a NEW pipe as you can afford, and as straight a run as possible.

 

[KLH]

Yes, the direction of flow is from right to left. The facilities people haven't a clue regarding its purpose.

Thanks to all for your help.

We are replacing all the exhaust piping and silencer. 2" for each manifold. 4" silencer and main to roof.

I was just curious what it was, never saw one before.

Thanks again.

 

[racookpe1978]

At your connection between the two 2" lines, try for a Y rather than a Tee going into the 4 inch line. Not essential, but try.

Alt: Use a 2 x 2 x 4 Tee

 

[Artisi]

It would be interesting to see the inside if and when you replace that section of exhaust.

 

[Ron]

If right to left flow, why would you want to increase the velocity of the gas through the silencer. Looks like a screw-up. Could also be some bastardized pressure relieve valving set up. Take it out and see what happens!

 

[ivymike]

well, if you note the diameters going into the gizmo and into the muffler, you'll see that velocity should be about the same before and after (if not for losses).

 

[MikeHalloran]

I could swear that it's a commercial _something_, that I have seen before, not a homebrew something ... but I can't remember what it is.



Mike Halloran
Pembroke Pines, FL, USA