Relationship Between Ash Accumulation and Smoke Output?

[Eric Johnson]

My boiler burns absolutely clean most of the time. People, including me, can't believe that a firebox full of burning wood produces nothing but heat waves. I can't believe you can get that much heat with so little environmental impact.

But occasionally, it will smoke. I've tried to figure this out without much luck. We're not talking much smoke--just a little white wispy trail that has very little smell (and not a bad smell, at that) and dissipates quickly once it gets into the air. But it bugs me. At first I thought it was steam, but I believe it's smoke. I've entertained a number of theories about this, most of which have been documented here in one place or another, and most of which have been discounted either through logic or observation.

Well, my theory de jour is that there is a direct relationship between smoke and ash buildup in the gasification chamber. When the boiler is smoking, in other words, it's time to clean out the ashes. Tried it yesterday and it worked. Prior to this, I've waited until the firebrick labyrinths below the nozzles basically filled with ash and coals before doing the cleanout, which is to say every 3 or 4 days. Now I'm inclined to start doing it more often.

 

[Nofossil]

My boiler burns absolutely clean most of the time. People, including me, can't believe that a firebox full of burning wood produces nothing but heat waves. I can't believe you can get that much heat with so little environmental impact.

But occasionally, it will smoke. I've tried to figure this out without much luck. We're not talking much smoke--just a little white wispy trail that has very little smell (and not a bad smell, at that) and dissipates quickly once it gets into the air. But it bugs me. At first I thought it was steam, but I believe it's smoke. I've entertained a number of theories about this, most of which have been documented here in one place or another, and most of which have been discounted either through logic or observation.

Well, my theory de jour is that there is a direct relationship between smoke and ash buildup in the gasification chamber. When the boiler is smoking, in other words, it's time to clean out the ashes. Tried it yesterday and it worked. Prior to this, I've waited until the firebrick labyrinths below the nozzles basically filled with ash and coals before doing the cleanout, which is to say every 3 or 4 days. Now I'm inclined to start doing it more often.

Most interesting. Of course, the labyrinth is probably the biggest difference between yours and mine.

IMHO, ash removal / ash management is the weakest aspect of the EKO's design. I wish it had a V-sloped floor in the upper chamber, and a fall-through floor with a cleanout pan below in the lower chamber.

My HX tubes are due for a cleaning as well. I haven't gotten the material to add turbulators, and it's a manual process for me :-(

 

[Eric Johnson]

How is that new labby working out for you, by the way? Looks like it would work pretty well, but I was wondering about where the ash goes and how often you have to clean it out. Can you do that without taking it out of the chamber?

 

[Nofossil]

How is that new labby working out for you, by the way? Looks like it would work pretty well, but I was wondering about where the ash goes and how often you have to clean it out. Can you do that without taking it out of the chamber?

It's a long and somewhat mournful story, perhaps better for another thread. My lightweight alumina bricks are becoming expensive lightweight gravel. I'm trying denser 3000 degree bricks next, perhaps faced with a layer of the lightweight stuff. The labyrinth gives me faster startup to gasification and lower stack temps, so I'm motivated to keep trying.

It's specifically designed to be easy to clean out without removing it. The end block on the top passage slides out, and the EKO-supplied 'hoe' tool is used to push the ashes (and melted ceramic debris) out the back of the top passage, where they fall to the bottom. Then, the same tool is used to rake out everything from the bottom passage as well as both sides. I have to remove it a couple of times per season to clean ashes out from the extreme back, below the HX tubes. I clean ashes about once per week - twice if I'm burning a lot.

 

[Eric Johnson]

The hoe tool works pretty well, I think. With the stock bricks, you just pull the hoe forward and the ashes drop into a shovel, and then into the can. It's easy and relatively clean, which is why I don't mind doing it every couple of days.

With my other two boilers, cleaning the ashes was a potentially huge mess and always a PIA. So they tended not to get cleaned out as much as they should have. (Notice I'm blaming them--not me--for that).