EKO 40 refractory block failure..

[hkobus]

My unit is just in the start of the 2nd season and on my last full clean up past Saturday, I pull the refractory blocks to gain access to the back of the secondary chamber in order to remove any ashes and crud from the HX. I do this about every 2 weeks. This time the first block was clean and no problem, the second block just crumbled in my hands as I pulled it to the front of the chamber. It is now in about 6 pieces and more cracks in the largest piece are visible. :bug:

Has anyone had this experience, I have experimented with the regular fire brick and had a row of 1 inch brick under the blocks to raise it and it greatly reduced the fly ash and burned the embers that dropped through the nozzle much better. I also blocked the back by moving the blocks against the back wall, and the front with some 1 inch firebrick. ( these don't last more than a few months.

My concern is that if the material used in the blocks is the same as the floor around the nozzle, how long is this all going to last....? :sick:

Henk.

 

[sdrobertson]

My unit is just in the start of the 2nd season and on my last full clean up past Saturday, I pull the refractory blocks to gain access to the back of the secondary chamber in order to remove any ashes and crud from the HX. I do this about every 2 weeks. This time the first block was clean and no problem, the second block just crumbled in my hands as I pulled it to the front of the chamber. It is now in about 6 pieces and more cracks in the largest piece are visible. :bug:

Has anyone had this experience, I have experimented with the regular fire brick and had a row of 1 inch brick under the blocks to raise it and it greatly reduced the fly ash and burned the embers that dropped through the nozzle much better. I also blocked the back by moving the blocks against the back wall, and the front with some 1 inch firebrick. ( these don't last more than a few months.

My concern is that if the material used in the blocks is the same as the floor around the nozzle, how long is this all going to last....? :sick:

Henk.

I'm just guessing here but with the refractory blocks up the extra inch it probably increased the temp that these had to endure to the high end of what they will endure. I think the nozzles are made of a different material and the hottest temps that the stove sees are right under the nozzles as there is air flowing through the nozzles to mix with the smoke. I would think that the hottest point would be about 2 inches below just like a torches hottest point. I think the rest of the bottom chanber will last as they don't get the full effect of the "jet engine". Keep in mind that I;m wrong allot of the time as shown by how many times I've changed my system!

 

[Brooksie1964]

Hey
The refactory brick is the same in the upper and lower chamber. Your problem is the flame is too close to the brick and that is what caused the brick to crumble. You need to have that extra inch away from the flame. I tried a full coal burn in my boiler after being told I could burn a 50% coal burn with no problem. I was told to put the coal on top of the wood and I would get a longer burn time. I did that and I did. So I asked why can't I burn all coal. They told me they didn't want that because if a clunker gets cause someone might crack the refactory nozzle. So I built a stainless steel form to go over the nozzle that prevented anything bigger the 1/2 from falling thru the nozzle. The Burn was great but.... after I let it got out to check my little s/s design I found the fire ws so hot it destroyed my grate. Next thought was to use tungsten for my grate. But after closer inspection of my nozzle I found the extra heat caused my nozzle to crumble around the edges. My nozzle is now about a 1/2 larger than I started.
The refactory brick is made to take so much heat than it crumbles, lower your brick ad I think it will last longer
Brooksie

 

[Nofossil]

I've had a long saga investigating refractory materials. The previous posts are right - the highest temps and most hostile environment is at the tips of the flame. My best guess is that that region sees temps as high as 2700 degrees - well into the ash fusion range where ashes fuse together from the heat. The original EKO refractory block is designed to trap ashes and allow the ashes to protect the refractory to some degree. Any changes that you make could expose the refractory pieces to higher temps and shorten their life.

They do make a high density / high alumina firebrick that's rated for 3000 degrees. These are available in full size and 'splits' (half thickness) and they hold up better than anything else I've seen. With a sacrificial layer of ceramic tile and ashes directly below the nozzle, I've had no failures.

 

[kb richard]

My furnace has soft bricks (Insulating refractory) They cut with a wood saw. However hard rbricks are a btch to cut. Use a small body grinder to score a grove then keep hitting harder and harder with a chilsel and hammer.

 

[Nofossil]

My furnace has soft bricks (Insulating refractory) They cut with a wood saw. However hard rbricks are a btch to cut. Use a small body grinder to score a grove then keep hitting harder and harder with a chilsel and hammer.

Or use a diamond saw blade and a Skil saw that you don't care about. Wear a mask and use water.....

 

[hkobus]

Well it sure looks that this experiment may have been the issue, all though there is only an issue with the one of two blocks. The second looks perfect and was the one most exposed to the direct flame.
I do agree that the standard firebrick don't stand up to the temps the ECO produces, I have a friend at a cement plant, they make their own liner for kiln and he claims the mix they use will handle the temps. We may try some of that the re-manufacture the blocks and at the same time redesign them a bit.
Since I raised the blocks, I have reduced the amount of ashes and the amount of wood I use. Also have the fan dailed way down. It looks to me like I am gaining on efficiency but being a little hard on the equipment.
This may just call for some more tinkering.. ;-)

Thanks for the comments.