Turbulators

[Eric Johnson]

I didn't know what these were until I helped slowzuki load up his Jetstream gasification boiler when he drove down here from New Brunswick to pick it up. Ken and the guy selling the boiler showed me the turbulators and explained that they direct the flow of the hot gas through the boiler's heat exchangers in a spiral pattern, which I seem to recall them saying effectively increased the dwell time in the tubes and thus the heat transfer.

I told them about the EKO, which has long sprial-bent pieces of steel in each firetube for cleaning. When you pull the lever on the hx cleaning assembly, these things move up and down (probably about 2 or 3 inches) in the tubes, knocking any accumulated soot back down into the ash pit. They're the same shape as the turbulators in the Jetstream, though they look like mild steel instead of stainless, and are not nearly as smooth or precisely manufactured.

But nonetheless, I suspect they serve a dual function as both turbulators and hx cleaners.

Does anybody know that for sure? Can any of you boiler gurus tell us a bit more about turbulators and their role in boiler design and operation?

 

[Corey]

Don't know about the boilers, but heat exchangers in general - any time you can break up a smooth / laminar flow, you can increase the heat transfer. Increasing the dwell time also increases the heat transfer. So the turbulators are a good idea for increasing overall efficiency.

I think the flue of my water heater has something similar...imagine taking a 3" x 5" piece of metal and giving it a 90 degree twist along the length, then stack up several of these so that they always meet at 90 degrees. It makes a twisty / corkscrew type thing that helps the flue gas transfer heat to the water.

The only downside (in my case) is that it also lowers the flue gas velocity and temperature, so in my natural draft system, it can't be too extreme of a turbulator. With forced draft if could be much more agressive.

 

[EricV]

I purchased the turbolators for my Tarm as an option. I don't think they have a cleaning function as when I clean the HX tubes I have to remove them and brush the tubes. It's a very fast but dirty job with the fly ash.

They are just pieces of 1/4" steel, maybe 2 inches wide with a wave pattern in them.

Eric

 

[Eric Johnson]

Sounds like the same thing without the cleaning function.

Since they're an option on the Tarm, what was the sales pitch? More heat transfer efficiency, I'm assuming.

 

[EricV]

Yes, more heat transfer but only recommended for installations with a storage tank as it does reduce the flue temp about 100 to 150 degrees. They recommend not using them for the first month or so.

I pulled them this am and did a good cleaning.



Eric

 

[slowzuki]

I have the drawing to make the Jetstream turbulators, they are just strips of sheet metal sheared and twisted with a hole drilled in the end, nothing too crazy. As mentioned their normal use is to increase heat xfer, I think the shifting them up and down to clean the fire tube is a great idea and will be seeing if I can do the same on the Jetstream.

 

[hkobus]

My EKO does not have this, but I will install them. A great product to use for this is flexauger coil. A barn equipment dealer would have this and is available in many sizes, even to fit in less than 2" tube.

 

[Eric Johnson]

Here's a pic of the top of the hx cleaner assembly. The turbulators/cleaners hang on a cam arrangement that rocks back and forth, pulling the rods up and down, when you pull on the handle. The soot winds up at the bottom of the tubes in the gasification/ash chamber.

 

[Nofossil]

Dang - another modification I have to make to my poor little EKO 25. If I get a 150 degree decrease in flue temperature, I'll be cooling the room with my chimney ;-)

 

[BrownianHeatingTech]

They are used in oil boilers, as well. They may not be "intended" for cleaning, but they sure help speed the process. Bang that thing around, spin it a few times, and scrape it up and down. After that, there is very little soot left to brush out.

Only downside to using them is when they sometimes warp, and won't come out. I expect the better ones are annealed after manufacturing, to make sure thye have no stresses in the metal which will deform it when heated.

Joe