graham
Junior Member
Posts: 74
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Post by graham on Jul 27, 2019 22:48:44 GMT -8
What's the maximum floor temperature and when is that achieved?
How long does it take to reach 500 deg C?
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Post by wiscojames on Jul 28, 2019 4:08:29 GMT -8
For pizza, I brought it to 425 C in about 4 hours. Not super fast, but very efficient with fuel, I believe, compared to a fiRe on the floor of the dome.
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graham
Junior Member
Posts: 74
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Post by graham on Aug 4, 2019 16:19:59 GMT -8
I'm having second thoughts about using a 5 minute riser again due to the possibility of ceramic fibers becoming airborne and then being inhaled.
So I'll probably tear down all my cooking stoves with black ovens that use the 5 minute riser and just use fire brick instead.
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Post by Vortex on Aug 5, 2019 2:26:38 GMT -8
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graham
Junior Member
Posts: 74
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Post by graham on Aug 5, 2019 11:11:11 GMT -8
Or, maybe just encapsulate the fibres of the ceramic blanket in rigidiser.
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Post by esbjornaneer on Aug 15, 2019 6:29:45 GMT -8
Hmm, it could work with just some chicken wire (or several single wires) on the outside of the blanket in that case... but with a min order of 500kg it would be in the region of 100 tubes surely? And the price range/kg being so large I wonder how expensive it would be even with a min order...
If the suggestion came due to the risk of airborne fibers I would suggest a biodegradable blanket instead. It is only rated for 1200C but It survived a test burn for a DSR2 core with a 1 meter chimney.
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graham
Junior Member
Posts: 74
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Post by graham on Aug 19, 2019 11:19:06 GMT -8
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JonS
New Member
Posts: 18
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Post by JonS on Apr 21, 2020 10:16:21 GMT -8
Hello, I have been working on a pizza oven with a 4" PBB that leads to a half barrel shaped oven. The dome is made out of Geopolymer (Thanks sksshel and Karl) and appears to be very strong. I wanted the system to be light enough to roll around on a cart but be large enough to make a reasonably large pizza as well as bake. I also wanted it to be able to heat up in a short amount of time. This is what it currently looks like:  As I read through this thread i realized that it is going to be hard to heat the floor of the oven. I was able to borrow a data logger and did some testing. I want to figure out the best arrangement before i mortar the dome on and and changes become more difficult. I know that i should have done different configurations starting from a cold oven but i only had the data logger for the weekend... These are the configurations i tried: -riser just entering the bottom of the oven. -extend the riser close to the top of the dome so it hits with more velocity and raps down the side.  -plate directing the flame at the floor.  -A mini dome to direct the heat down.  I placed a TC in the fire box, at the bottom of the riser, the top of the dome and the floor of the dome. As you can see, it is hard to heat the floor of the oven. (the gray trend). I kind of liked the mini dome condition because it seemed to warm the floor and the top of the dome didn't heat as hot (sort of like more heat was directed down instead of it all going up... ) My next firing I will try starting out with the mini dome and a fuller load of wood to start out. Does anyone have a recommendation on another way to heat the floor that i could try as well? I was trying to think of a ridge after the mini dome that worked sort of like a snow fence to pull the heat down but wasn't sure where to place it. I think getting the floor of the oven up to 200C should cook a pizza but i don't want it to take 2 hours. Also, the batch rocket is awesome! I over fueled it a couple times but it recovered quickly and the smoke went away. 1100C is impressive and i don't know if my K-type TCs are accurate at a much higher temp! ![]() |
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Deleted
Deleted Member
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Post by Deleted on Apr 22, 2020 1:11:45 GMT -8
The simplest way to get a quick warming floor
is a flame path below a thin plate.
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JonS
New Member
Posts: 18
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Post by JonS on Apr 22, 2020 5:04:44 GMT -8
Thanks for the feedback Karl. I just realized that the temperature plot didn't post. I will try again.  I was sort of thinking about a set of pizza stones ~1" above the top of the riser but I figured that they wouldn't be able to handle the thermal shock. When the bottom of the riser hits 1100C the top is ~1000C. Perhaps a geopolymer plate to take the brunt of the heat and then pizza stones further away? |
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JonS
New Member
Posts: 18
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Post by JonS on Apr 27, 2020 17:05:39 GMT -8
Yesterday I tried a firing with just the mini dome above the heat riser for the entire run. The floor got up to 200C in 40 minutes and 277C in an hour. That is a little longer than I would prefer but it also keep it's heat for a long time after the fire died down. I'm going to try pizzas tomorrow so I guess that will be the true test...
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Deleted
Deleted Member
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Post by Deleted on Apr 29, 2020 6:38:43 GMT -8
One can use white high purity (>99%) corundum as an addition to geopolymer or fire cement to increase heat conductivity and capacity.
Specific gravity 3.95–4.10
Thermal conductivity 41.9 W / (m · K) and the thermal capacity 754 J / (kg · K)
Silicon carbide
Specific gravity 3.16
Technical SiC approx. 100–140 W / (m · K)
Thermal capacity
20°C ~ 670 J / (kg · K)
1000°C ~ 1270 J / (kg · K)
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JonS
New Member
Posts: 18
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Post by JonS on Apr 29, 2020 9:17:54 GMT -8
Thanks Karl,
Do you have any thoughts on using cordiorite grog as a portion of the mix instead of kaolin? I have some on hand and considered experimenting with it but didn't know if it would disrupt the chemistry.
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Deleted
Deleted Member
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Post by Deleted on Apr 30, 2020 4:50:45 GMT -8
Cordierite is an aluminosilicate with additional magnesium Mg2Al3[AlSi5O18] or maybe with magnesium and iron (Mg,Fe)2Al3[AlSi5O18]. Geopolymerization should work with pure cordierite grog or mixtures of cordierite grog and other aluminosilicates. Pure cordierite grog is rarely used for geopolymers because it is very expensive, but there are some papers about mixtures of fly ash or metakaolin and cordierite grog.
Effect of cordierite addition on compressive strength and thermal stability of metakaolin based geopolymer |
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Post by ahansen on Jun 3, 2020 22:57:35 GMT -8
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