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bwsaunders

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  1. bwsaunders

    Old Alpine Conversion

    Neil- that was a concern for us as well, but there is actually about inches between them. We're going to wrap about 18" of it with kaowool just in case.
  2. bwsaunders

    Old Alpine Conversion

    Wanted to post an update as its been a couple months. Since I posted last the kiln has been moved onto the foundation and bolted down, had a frame welded for the chimney and the stack cut in through the roof, and most of the burner manifold built. Once we get the union aligned, it will be time to build the chimney and move closer to first firing. So nice to see a project coming together after a long time.
  3. bwsaunders

    Old Alpine Conversion

    Neil, well, as I have it designed, there would be a 5" channel following the taper off the interior walls from the fire box all the way up. I'm not sure about what size shelves were originally used, but would love to know if you do. If I do use a row of bricks on each side of the firebox, I'd have 27" of space along the bottom ( side to side) which I may do to avoid having the bottom row get too hot during during. What size would you suggest?
  4. bwsaunders

    Old Alpine Conversion

    Wanted to post an update. Since I first posted, the kiln has been repainted (in progress in the photo), moved just outside the studio area and a kiln footing poured. As the 4 burners will be firing up into the side fireboxes, more height was needed than that from the 6" legs (removing the old rusted wheels so the feet set solid on the pad. I'm waiting for the cement to dry and will hopefully have our neighbor use their forklift next wed and move the kiln into position, and then I can add the structural bolts to secure it in place. With help, I've rerouted the gas lines and added a shutoff, and now need to build the burner/pilot manifold and hook it up, and build the chimney. I'll be building the manifold with 4 MR-750 burners, and the chimney out of soft brick (tied in with some angle iron and iron webbing. I secured a nice stack out of stainless steel, and feel pretty good about my design for the chimney. The only thing I'm still looking into is shelves. Towards the bottom, a 32x20" shelf area would be optimal, with that tapering towards 24x20" towards the top. I was thinking of buying (4) 20x20" shelves and cutting each of them down to 16x20's. I hate doing that, but I don't know of any that size, and I'd like to use as much space as possible. Any ideas? Mark, picked up the colloidal silica and the milled zircon for the kiln coating from Phoenix today. Will probably spray the bricks once I get the kiln in place and finish up doing the cutting for the new exit flue. More as it happens. Hoping to have it firing by May 1.
  5. bwsaunders

    Chimney Entrance Reduction

    Agreed. It's hard for me to do things like this without clearer understanding. And because I don't build kilns very often, I'm definitely overthinking this. I'm sure it will be fine, I'll do the exit flue in a way that can be reduced, and the chimney such that the damper can control flow. I just get nervous thinking about a 9x4.5" chimney. It seems really small, but at the same time it's a small kiln.
  6. bwsaunders

    Chimney Entrance Reduction

    Thanks for the follow-up. I've done a lot of reading since posting (Fred Olsen's The Kiln Book, Nils Lou's The Art of Firing , Mel Jacobsen's 21st Century Kilns, and even Kiln Construction by Joe Finch), and have also plugged in numbers from different kilns in the books and those I have access to locally. Unfortunately, there are no consistent ratios here. I love the idea of the double venturi as described by Nils Lou, but after running the numbers on his MTF kiln (that he uses as an example of a double venturi), I found the area increases after the entrance to the exit flue as follows: 31.5"² @ exit flue >35"² @ base of chimney >41.5"² @ damper >81"²@ chimney >31.64"²@ the reduction at top of chimney/base of stack. The second venturi at the top of the chimney/base of the stack is really clear, but the exit flue into the chimney increases in area, which would decrease pressure and velocity, not demonstrating a venturi effect. Here are my numbers. 4 MR-100 burners firing into 3" diameter intake ports give me an intake area of 28.28" sq. I'm designing the exit flue to match that and will be 4.5" tall x 6.28" wide (28.28"sq). From here, Fred Olsen suggested a 25% reduction at the back of the exit flue, which would be consistent with a double venturi design. I'm creating a spot in the back of the exit flue/base of the chimney to insert brick and decrease the flow area. A 25% reduction is about 4.71" wide by 4.5" tall (21.2"sq), opening to my chimney base which will be 9x4.5" wide (40.5"sq). I can decrease again at the top of the chimney heading into the base of the stack to create a second venturi, but I'll figure that out once I get an exit flue and chimney size I feel good about. Two examples from research. A similarly designed downdraft at FireArts fires with 6 MR-750's, and has a combined intake size of 29.46"sq. The exit flue entrance is 42.19, opening to 64.12"sq, and opening again to 76"sq going through the damper. It then opens again to 108"sq above the damper. Not sure on the size of the decrease at the base of the stack. That means the exit flue is 43% larger than the intake, opening an additional 74% through the exit flue, and even more still through the damper and chimney. Next, we have Vince Pitella's Downdraft Soda Kiln. 3 MR-100's fire through 60"sq of intake. That feeds through a flue 9x7.5" (67.5"sq) and into a chimney 9x9" (81"sq). So, despite lots of research, I'm not all that clearer about the science. Thoughts?
  7. I have a question regarding some theory I read in the text The Kiln Book. On page 78 of the 4th Edition, it states that: "At the point where the exit flues enter the chimney, they should be restricted so that the chimney cross section is larger than this flue area" In the diagram (3-11) beneath this, it shows decreasing the point of entry to the chimney by 25% (from 4 bricks to 3), coming from the kiln exit flue. What's the thought behind this? I'm happy to trust my elders, but I'd also like to know what the theory is. I'm curious how this decrease affects the firing, vs keeping the same area of flow in the inlet flue>exit flue>chimney entry>chimney. As I'm building a chimney coming up in the next couple weeks, I'd love to figure this out. I can taper in the walls of the exit flue to the entry point of the chimney, which would accelerate flow heading into the chimney (while also creating slight backpressure?), which would then open back up to the full area of the chimney as it rises. Thoughts? Thanks in advance!
  8. bwsaunders

    Old Alpine Conversion

    Hi Mark. Yes, it's in Arcata. It was donated to FireArts, but has been sitting a while. Looking forward to getting it going again.
  9. bwsaunders

    Old Alpine Conversion

    Hi Neil. As none of the original burner/blower system remains, and as it's going to be cost prohibitive to rebuild it, I will need to modify the burners as outlined either way. As for the chimney, I need to cut a hole in the roof out of the firing area and add a storm collar, etc. and wont be able to move the chimney once it's installed (and there is only one position for the kiln, so I can't shift it). If I fire it updraft with the new burners and don't like it, I'll be stuck. For that reason, I'm going to stick with this updated design. Building a chimney out of softbrick isn't that complicated or expensive, even with the costs of welding the frame out of angle iron. Thank you for the suggestion though. If I had the option to build everything out and test fire it as updraft, without being locked in, I would.
  10. bwsaunders

    Old Alpine Conversion

    I'm beginning a kiln conversion/update project and thought I would create a thread here for those interested, and to get feedback as I go along. I have access to a late 1950's Alpine kiln, and now have a place to fire it. It's been sitting for a long time, but I believe will be perfect with a little time and TLC. All the bones are solid, and other than some rust on the exterior, I think it will work great (estimated 12-14 cubic feet). My primary interest is having it as a cone 10 reduction kiln, specifically to experiment with shinos. The kiln was originally designed as an updraft kiln, two forced air burners entering low on either side of the front next to the door. As I've read these kilns could be hard to fire evenly, I'm converting it into a downdraft kiln with floor fire burner placement. Ill plug up the original vents on top and need to build an exit flue and chimney behind the kiln. I've attached my designs for what I propose. At this point trying to decide between MR-750 and MR-100 Venturi burners (4 total firing on Natural Gas). Would love to hear from you if you have any positive suggestions. Thanks and I'll keep you posted as it unfolds.
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