Author Topic: The power of coal  (Read 1055 times)

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Offline shuboyje

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The power of coal
« on: April 04, 2014, 12:33:09 PM »
I thought some of you guys might enjoy this video showing the insane heat capacity of coal.  This is during one of my test fires in my new coal oven.

http://m.youtube.com/watch?feature=youtube_gdata_player&v=BOgZbgIYf1I
-Jeff


Offline scott123

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Re: The power of coal
« Reply #1 on: April 04, 2014, 12:56:38 PM »
That's HOT! I'm sweating just looking at it!  ;D

How tall is the wall between the coal and the baking chamber?  Do you think that's going to be tall enough? The divider at Pepe's feels like it's about 7/8th the height of the oven.


Offline shuboyje

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Re: The power of coal
« Reply #2 on: April 04, 2014, 07:52:12 PM »
The wall is 2" above the floor.  So far it's functioning perfectly(I've done a few pie's in the oven but none is optimal situations yet).

I could easily extend the wall up if needed, but do not think that would function well in this design.  I can tell you from experience that the oven does not function well with the flue inlets lower then that wall until it is very hot.  It takes a good amount of pressure to get it to down draft like that.  If the wall was higher the flue inlet would have to be pretty far up and I would lose a lot of heat during warmup.

In this design the wall serves 3 purposes.  It increases the height of the fire box which leads to increased airflow,  it blocks the direct straight line radiation from the coal to the edge of the pizza, and it has secondary air inlets built into to supply pre-heated secondary air for burning volatile fuels(wood).  It is working very well in all three functions.
-Jeff

Offline scott123

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Re: The power of coal
« Reply #3 on: April 04, 2014, 08:29:19 PM »
Well, perhaps I'm letting the video color my perception a bit too much (you'd obviously never bake pizza with that much flame) but it feels like, even with a weak coal fire, the wall may not block enough radiation. If your pies are baking well, though, then that's all that matters.

I'm curious, do you foresee yourself needing to rotate the pies about as frequently as a traditional coal oven, or have you designed this oven to require less turning?

Offline shuboyje

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Re: The power of coal
« Reply #4 on: April 04, 2014, 08:43:16 PM »
The oven is 1200F in that video Scott, no pizza getting cooked then, lol. 

I hope with a very saturated oven and a proper amount of heat coming from the coal the oven is pretty even, but in my experience so far it will require some turning no matter what. 
-Jeff

Online Pete-zza

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Re: The power of coal
« Reply #5 on: April 04, 2014, 08:52:23 PM »
Jeff,

Would you mind telling us why you are designing a coal fired oven? For example, it it for your personal use and to learn from the experience, or might it be a precursor to a commercial oven?

Peter

Offline scott123

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Re: The power of coal
« Reply #6 on: April 04, 2014, 08:57:11 PM »
Would you mind telling us why you are designing a coal fired oven?

+1

Inquiring minds want to know  ;D In a similar vein, you haven't documented this build as much as your Neapolitan oven adventures.  Are you keeping this under wraps or just haven't had the time to document?

Offline shuboyje

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Re: The power of coal
« Reply #7 on: April 04, 2014, 09:16:10 PM »
Jeff,

Would you mind telling us why you are designing a coal fired oven? For example, it it for your personal use and to learn from the experience, or might it be a precursor to a commercial oven?

Peter

When I built my second wood oven I put in an 18" door so I could make 18" coal oven style pizza.  I promptly fell in love with this style.  Being the idealist I am I've wanted to build a coal oven ever since to cook them in, so I finally jumped in with both feet and did it.  I haven't documented it for a few reasons, but the biggest being this oven is working with a lot of unknowns.  Where do you find the info for fire box size ratio compared to the oven size?  What flue height should a sealed chamber coal oven have?  The list goes on and on.  I've dug and pulled info from lots of unconventional sources...for instance the fire box sizing came from a manual on design coal burning reverbatory furnaces for melting metal. 

Long story short I don't really want to document this oven too much until I know it works.
-Jeff

Offline scott123

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Re: The power of coal
« Reply #8 on: April 05, 2014, 01:16:13 AM »
Long story short I don't really want to document this oven too much until I know it works.

Got it.  Knowing your abilities, I think the chances of it working are astronomically high, but I can understand your need for due diligence.  When the time comes, I'm greatly looking forward to any detail you'd be willing to share.
« Last Edit: April 05, 2014, 01:29:00 AM by scott123 »

Offline stonecutter

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Re: The power of coal
« Reply #9 on: April 05, 2014, 12:49:39 PM »
What's the humming sound...the draw from the air inlet or a fan?   Looks like a cool project, you should put some build pics up.
http://oldworldstoneandgarden.com/

Look at a stone cutter hammering away at his rock, perhaps a hundred times without as much as a crack showing in it. Yet at the hundred-and-first blow it will split in two, and I know it was not the last blow that did it, but all that had gone before.
Jacob August Riis


Offline shuboyje

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Re: The power of coal
« Reply #10 on: April 05, 2014, 01:03:46 PM »
That would be the dryer vent running about 10 feet behind me, lol.  One of my main goals for this project was it had to be 100% natural convected.  I have designed it so I could add a blower worst case scenario, but I'm now confident I won't need to.
-Jeff

Offline scott123

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Re: The power of coal
« Reply #11 on: April 05, 2014, 01:07:46 PM »
No fan?!? WHAT?!?  ;D

Offline shuboyje

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Re: The power of coal
« Reply #12 on: April 05, 2014, 01:25:12 PM »
Of course no fan, who wants to tote around a fan.  This oven is also portable. 
-Jeff

Offline scott123

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Re: The power of coal
« Reply #13 on: April 05, 2014, 01:39:25 PM »
Portable?!?  :o

Alright, now you're just showing off  ;D

Offline shuboyje

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Re: The power of coal
« Reply #14 on: April 05, 2014, 01:49:32 PM »
It's just a little fella Scott, a one pie oven with a 22.5x22.5 cooking hearth
-Jeff

Offline scott123

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Re: The power of coal
« Reply #15 on: April 05, 2014, 01:54:21 PM »
Does the size relate to the fanlessness or can this be scaled up and still work with natural convection?

Offline shuboyje

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Re: The power of coal
« Reply #16 on: April 05, 2014, 02:05:54 PM »
If it works it could all be scaled up.  The lack of fan is created by the firebox design, which would stay the same just proportionally larger
-Jeff

Offline Tscarborough

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Re: The power of coal
« Reply #17 on: April 05, 2014, 02:16:35 PM »
It looks pretty cool, how hot have you gotten it, or rather, what is your desired temp range, 750-800?

Offline shuboyje

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Re: The power of coal
« Reply #18 on: April 05, 2014, 02:25:00 PM »
I'm shooting for a deck temperature of about 700F.  In my wood oven that puts out the type of bake I want with the WG bricks.  Like I mentioned early that video was just before the oven hit 1200F.  I designed it to allow wood on top of the coal for Neapolitan bakes as well, and that functionality works well.  If you didn't know better you would think I pumped gas into the secondary air inlets, they look like burners throwing flame across the oven when burning wood. 

The biggest learning curve is working with the coal, it's a whole different beast.  Full disclosure that video was taken about an hour AFTER I had cooked pizza with wood and coal.  I had messed with the coal trying to get it to radiate enough to heat the floor and finally added some wood which quickly heats the floor.  I let the wood burn down to coals then cooked some pizza at around 600F.  An hour later I went out to check on it and found THAT situation going on.  Obviously I'm messing with the coal to much.  My goal now it to get the coal burning like that and then to dial it down with the flue dampers.  In that video I hadn't even installed the dampers yet as there had been no need for them thus far.  So, I know the oven works now, I just don't know how to operate it, ROFL.

 
-Jeff

Offline scott123

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Re: The power of coal
« Reply #19 on: April 05, 2014, 02:37:07 PM »
Jeff, with the amount of natural convection going on, there's no chance that coal or wood ash will land on the pizza as it bakes (a la uuni), right?


 

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