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R Fraser

Member Since 20 Oct 2011
Offline Last Active Apr 13 2013 04:14 PM
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Posts I've Made

In Topic: What direction is your wheel spinning?

08 April 2013 - 12:31 PM

I thought is was like toilets flushing and tropical storm rotation, it depends on your location relative to the equator?
Richard

In Topic: Building a cone 10 outdoor Gas/Salt Kiln

28 March 2013 - 02:21 PM

I too found finches book helpfull. The price on Amazon has got to be an error because that is where I bought mine and it was well less that 700 USD! Amazon was kind enough to offer to buy my used copy for 2.03 USD though! Talk about depreciation.
Richard

In Topic: help needed evening out my kiln temp differences

28 March 2013 - 02:14 PM

Since I'm a welder I don't think it would be that difficult for me to build. What I'm not sure about is whether I would get enough recycling of heat to be worth the trouble.


The Sandia Forge reported up to 30% improved efficiency if I remember corectly. Nils Lou suggested significantly increased efficiency with his recuperating power burner set up but I do not remember if he made any specific claims. I would be concerned that depending on the location of the recuperators and the temp of the exhaust gases a closed loop system relying on natural draft flow to feed the burners primary air the CFM flow of primary air may be low, possibly too low to offer any meaningfull cooling of the recuperators and thus the burner. This would also limit your ability to control the kiln atmosphere to regulating the secondary air flow. The more I think on it the more it seems that to use a recuperating design safely and effectively you are almost obligated to use a blower fed burner system.

Nils Lou's book "The Art of Firing" has a nice schematic outlining how to set up a recuperating kiln burner using a power burner system along with a ton of other great kiln construction info, probably the greatest information density per dollar of any kiln building books I bought second only to Olson's Kiln book. The plans and breif outline on design are at the end in an appendix if memory serves..

This is a link to the ABANA web site with the forge plans: ABANA Forge plans
Note that this is a very small volume chamber with very short primary air supply tubes to the atmospheric burners in more or less a closed loop design.

Richard

In Topic: help needed evening out my kiln temp differences

27 March 2013 - 03:15 PM

This relates to a project that I've been contemplating for my torchbearer.

I thought about building a heat exchanger around the exhaust port , then pumping the hot air back underneath the kiln so that it will be picked up by the burners. this would hopefully recycle some of the heat and feed warmer air into the bottom of the kiln. this might be particularly useful for me since where I fire the kiln it is often 30 to 40° in there. So it's getting very cold air coming in the bottom. Air few hundred degrees warmer might be helpful.

Has anyone tried anything like this?
Any thoughts about this strategy


This sounds like a recuperating (spelling?) type furnace I first read about when making my first blacksmith forge, I found the plans on the Sandia website (many years ago). It called for oval stainless steel pipe(s) running through the exhaust vent that was then collected and used to supply combustion air to the burner(s). These were atmospheric burners, and it was a small furnace < 2 cubic feet. In Nils Lou's book "The Art of Firing" he talks about a similar design for a ceramic kiln, but it is using a power burner with the blower first running through a pipe matrix in the exit flue to pick up heat before feeding the burner itself. I would say that everything from the flue to the burner would have to be stainless steel. I do not think this would be easily to make safe or simple using atmospheric burners.
Richard

In Topic: Building a cone 10 outdoor Gas/Salt Kiln

27 March 2013 - 02:58 PM

I just built a kiln of this size and to fire to cone 10 in 8 hours (roughly) it needs 320,000 BTU/Hr input, and I have 2 burners that are fueled by high pressure propane that will put out 150,000 BTU/Hr on 3.5 PSI. I have fired several times now and have to throttle back to make it to 8 hours. The design is mostly a modified Oregon Flat top design as discussed in Nils Lou book the art of firing. The Burner you have pictured looks like a MR 750 or MR 100 style burner, but as pointed out type of fuel and how supplied, your elevation, orifice size, size of supply pipe, regulator capcity all influence final burner output. Marc Ward is a super resource on burner questions.
Here is a link to the thread I started when I finished my kiln;

My First Kiln Build

Good luck!
Richard