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Post by bmeagle on Jan 23, 2012 7:27:02 GMT -8
peterThanks, that is exactly the advice I was looking for!
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Post by satamax on Jan 26, 2012 11:50:18 GMT -8
Guys, if this can be of any intrest, an old friend of mine who's geologist, told me that quartzite is refractory, it's a stone, and often can be found localy. May be cruched it would be a good mixer.
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Post by bmeagle on Jan 30, 2012 0:44:35 GMT -8
I've ordered my kaolin. For possible future reference for anyone from SA. I am getting it from Hippo Industrial Chemicals in Boksburg who are a distributor for Serina Trading www.kaolin.co.za/kaolin.html |
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Post by bmeagle on Mar 22, 2012 11:22:45 GMT -8
@peterburg You have experience with castable ceramics. There is a local company here in SA called keramicalia. They have some intresting castable refractories, see: keramicalia.co.za/cellular-insulation.htmlThe company for whom I work has dealt with them. We had some high temperature stuff made by them. I am considering using this instead of insulating bricks for my burn tunnel and heat riser. Keralite2, Keralite8 or Kerapour seem like good choices. What do you think? I am going to contact the guy and hope that vibrating tables won't be necessary! |
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Post by peterberg on Mar 22, 2012 12:07:31 GMT -8
Keralite2, Keralite8 or Kerapour seem like good choices. What do you think? I am going to contact the guy and hope that vibrating tables won't be necessary! Properties of the materials look very good, although Keralite8 has 800 C only as the highest service temperature. What you need is at least 1200 C material, and not a very porous one because of the risk of damaging the sides and bottom of the feed tube. These properties aside, the lighter the material, the faster it will come up to the highest achievable temperature. It would be very interesting to build a rocket heater out of that. |
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Post by Deleted on Mar 23, 2012 1:55:05 GMT -8
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Post by bmeagle on Apr 1, 2012 12:00:07 GMT -8
Hi guys
This is what my plan to build the coming long weekend looks like.
Inspired by you all!
I drew this based on a 200mm x 100mm x 50mm (8" x 4" x 2") brick.
The chimney is 150mm x 150mm (6" x 6") square.
Hole for the flue pipe is 200mm x 200mm.
Burn tunnel is 200mm high and 150mm wide.
Feed tube hole is 100mm x 100mm.
This week I'll sort out my fire bricks, whatever I can get.
In SA firebrick is hard to get if you're a normal person, only the commercial guys with furnaces and guys building pizza ovens are the in the market. I'll see what keramicala comes up with, I think their stuff is going to be pricey.
Work is letting up to normal a bit, so hopefully I can post a photo soon!
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Post by Deleted on Apr 2, 2012 5:23:43 GMT -8
The most intresting stuff for casting and general insulation are the powders of hollow balls.
With them one can make almost everything self leveling and self deairing,
als even small amounts of the bubbles will lower viscosity a lot.
A cheaper alternative would be microballons of glass used as lite fills for resins and polymers.
Bulk density is about 130g - 150g per litter.
The glass will melt at high temperatures, but this will not be a real problem.
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Post by peterberg on Apr 2, 2012 6:04:51 GMT -8
bmeagle, It looks like you are going to make the burn tunnel higher than wide, and the largest section of the system. According to the drawing, feed tube is 100 cm2, heat riser 225 cm2, burn tunnel 300 cm2, outlet 400 cm2. The whole system should be the same sectional surface area except the bell, I'm afraid this won't work. In order to achieve good performance, it's also necessary to insulate the riser, tunnel and feed. And last but not least: it's best to have the riser centered inside in order to have the same temperature around in the bell. Please, do build one outside as an experiment and see how it performs.
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Post by bmeagle on Apr 2, 2012 6:48:18 GMT -8
peterThanks for reminding me about the sectional area. I'm going to use insulating fire brick for the feed tube, burn tunnel and riser (the yellowish brick, Al2O3 40.26% SiO2 44.9%, just got the quote this morning, about $2.4 each) The red brown brick will be normal clay pavers or facebricks. Somewhere in this forum I read that the feed tube sectional inlet area needs to be half of the riser sectional area, or am I confusing different things? My flue outlet size as drawn doesn't mean much, I just took out bricks to be able to fit a round pipe, will have to close up the gaps. I'll change my design to ensure the burn tunnel and riser have the same sectional flow area. Peter somewhere you stated all the action happens in the burn tunnel, from that I presume the hot air has finished expanding before entering the riser and my burn tunnel is probably too short then... My bell asymmetry has been bothering me, maybe I'll change this to look more like your first big tall single bell design, with a horizontal firefox / feedtube.
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Post by peterberg on Apr 3, 2012 8:38:33 GMT -8
Somewhere in this forum I read that the feed tube sectional inlet area needs to be half of the riser sectional area, or am I confusing different things? I think you do. Everybody want to make the feed tube wider and it won't work most of the time... So having all nearly the same area would be your safest bet. These insulating firebricks are very interesting, I am awaiting the results. Peter somewhere you stated all the action happens in the burn tunnel, from that I presume the hot air has finished expanding before entering the riser and my burn tunnel is probably too short then... Burn tunnel could be a bit longer, yes. But my statement was made about the experimental rocket with bells and whistles. The better it went, more of the action happened in the tunnel. I wouldn't dare saying it's an universal rule, there are lots of roads leading to Rome, after all. My bell asymmetry has been bothering me, maybe I'll change this to look more like your first big tall single bell design, with a horizontal firefox / feedtube. Placing the riser in the center of the bell will lengthen the tunnel somewhat, I'd think. |
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Post by bmeagle on Apr 5, 2012 2:40:22 GMT -8
Here is a picture of one of the culite h bricks. It is made with a sand and fine vermiculite mix and a binder.
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Post by bmeagle on Apr 15, 2012 12:07:11 GMT -8
Hi guys Today I report back with some video, I dry stacked my fire bricks and messed around a bit. Burnt some paper and then a stack of wood! Enjoy: youtu.be/nJpETIecX_QI messed around with some waste oil as well. I think burning waste oil together with wood, say about half way through the normal woud burn could work out. I'm going to experiment with that after this thing is up and running. @peterburg What do you use to cover the roof of the bell? Would normal concrete building lintels survive at the top of a bell? I suppose a lot of mixing of the hot gas from the riser should occur. |
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Post by leewaytoo on Apr 16, 2012 6:09:25 GMT -8
suggestions regarding shooting of video.. to be used or not..
think of shooting video as if you were writing a story..
a wide shot from the four 90degree pts of a compass to set the location.
then closer shots to capture the action or to explain what is transpiring..
sometimes move back to the wide shot to re-establish the location, as conditions change.
first and foremost, your effort to shoot the video and post on utube is the most important
contribution,
thank you.
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Post by peterberg on Apr 16, 2012 6:51:17 GMT -8
@peterburg What do you use to cover the roof of the bell? Would normal concrete building lintels survive at the top of a bell? Normally, refractory concrete or stepping in with fire bricks. On the other hand, when the top of the bell is sufficiently far away from the mouth of the riser, it's possible to use concrete pavers without steel rebar in it. The pavers are able to withstand a temperature of 300 C. without damage. The dangerous point is at 540 C. if I recall correctly. Around that temp the christals in sand are changing from one structure to another, accompanied with rapid expansion. So, concrete building lintels won't do because of the steel inside it. This will expand faster compared to the concrete and tear it apart. |
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