Here is a photo essay on the soda ash kiln we built awhile back.
Thanks to Ron Immer for his construction expertise and input. All photos by Kevin B.
The floor was constructed using large high alumina tile I found at a furnace rebuilding business. They were actually made to be used as a lid for the exit area of an industrial furnace. We leveled an area in my kiln shed and began with an idea.
The finished tile floor, minus the exit chimney floor which we added later. The high alumina tile withstand the soda vapors very well.
We used many of Fred Olsens equations on the design with a few alterations. We tried to stick with the input size of air coming in would match the exit flue coming out.
The lower wall was made with keyed tougue and groove brick sourced from the same furnace company. The walls are all 9" thick, the lower wall was lined on the outside with 9" x 9" K23 soft brick.
This photo shows the lower brick layup with the K23 soft brick lined up along the outside. Also visable are the burner and soda ports along with the exit flue.
With the lower wall installed we started on the chimney and damper slot. Here you can see the extension we added for the chimney. The damper is an old mullite shelve.
We used angle iron to support above a cut mullite tile to make sure we had strength above the damper slot span.
We used a welded steel fence sourced from the local farmers supply to " cage" the kiln. The frame is made with angle iron with welded tabs where we used 3/8" threaded rod to tie the frame together.
As the kiln started to take shape we "squared" up the frame with the threaded rod. Here you can see the tabs that were welded for the rod.
The upper walls were lined on the inside with K26 insulating brick. The outside with K23 brick.
A detail of how the angle iron and tabs fit.
This photo shows the completed walls up to the skewback and arch addition. The hot facing of the K26 softbrick are coated with a mixture of 50/50 Kaolin and silica. After numerous firings this has turned into a glassy surface which protects the soft brick material.
Now that the walls were getting in place it was time to build the arch support. I used 3/4 ply and cut the shape with a band saw.
I used a doorskin to span the arch and give support while we layed up the arch.
The arch support itself was installed and leveled used 2 x 4's screwed together so we could remove easily when the arch was completed. In this photo you can also see the start of the floor and baffle along side the flame box.
This is how we layed the brick in. The skewbacks were cut from hard brick and a 2.5 x 2.5 angle iron was behind the skewbacks for support along the wall.
The arch roughed in without yet trimming the front brick. You can see the skewback here along with he angle iron support.
With the arch in and the facing bricks trimmed and flush it was time to build the door. I used angle iron and expanded metal. I added an extra iron strap along the perimeter of the door for added support of the brick.
The door frame welded up and temporarly set into place. The two vertical pieces of iron will be the main support on which the door will hang.
Side view of welded door. The edge of the iron is up tight against the kiln frame which gives as much brick to brick contact as possible for insulation.
With the frame completed we hung the "I" beam in place, installed the door trolleys and hung the door frame. We moved the door over where we could tilt it to install the insulation. First we used insulating fiber board, then K26 layed flat, giving 5 1/2" of insulation. We used 3/8" threaded rod as far back from the hot face as we could manage and still hold the brick in. We also used "Sairset" morter to cement the brick in. The bricks were set in water to soak before the morter was applied.
This photo shows just how tight we were able to get the front face and door to fit. It also shows the door latching system I used to secure the door.
I used two B-4 burners rated at approx. 500,000 BTU's each. The propane gas pressure at each burner is about 6 lb's each. The kiln fires to cone 10 in about 9/10 hours.
Completed with peep and draw ring holes. I use a "Bartlett" pyrometer to gauge temperature rise.