top of furnace

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zappymax
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Joined: Wed Dec 26, 2012 6:59 pm

top of furnace

Post by zappymax » Fri Dec 28, 2012 2:39 am

1) is it "better" to use a metal covered hat on top of furnaces (with refractory material inside, under the metal cover ) or just a steel circle with refractory (the two with exhaust holes on top) as heating and cooling cycles will always produce some breaking of the refractory stuff used. Is the metal covered top more resistant ?
2) if i use compressed air with a LP gas venturi , should the air injector be directed in a specific way or just parallel to the LP gas sprayer ? In such a case, should the end of the air injector be in a specific form/design, and be installed just before, just next the gasifier or "more inside" of the gas sprayer into the furnace ? Any advice welcome.
3) The furnace is practically soldered, now need inside lining. Picts will follow.
4) Is it a good idea to use fiberglass outside of the steel furnace to help keeping heating process and spare fuel ?
Thanks
Pat

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
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Re: top of furnace

Post by Harold_V » Fri Dec 28, 2012 4:28 am

zappymax wrote:1) is it "better" to use a metal covered hat on top of furnaces (with refractory material inside, under the metal cover ) or just a steel circle with refractory (the two with exhaust holes on top) as heating and cooling cycles will always produce some breaking of the refractory stuff used. Is the metal covered top more resistant ?
My opinion?
A steel band, one that is capable of clamping the refractory material to keep it intact. I'd personally avoid a metal cover, if for no other reason, its ability to conduct heat (exposed to the exhaust stream) and to corrode, possibly dropping oxides in to the heat, contaminating the charge.
2) if i use compressed air with a LP gas venturi , should the air injector be directed in a specific way or just parallel to the LP gas sprayer ? In such a case, should the end of the air injector be in a specific form/design, and be installed just before, just next the gasifier or "more inside" of the gas sprayer into the furnace ? Any advice welcome.
Compressed air? Like from a piston type compressor?
I used old upright vacuum cleaner motors for two furnaces I built, both of which were fired on natural gas. I introduced the gas at a right angle to the air stream on both of them, which appeared to work quite well. I regulated the gas flow as well as the air flow with gate valves. Remember, you really want the gas to mix with the combustion air, not just be introduced to the furnace randomly. The air/gas mixture should be introduced to the furnace on a tangent, so the fire swirls around the chamber, from bottom to top. The flame should not impinge directly on the crucible.
3) The furnace is practically soldered, now need inside lining. Picts will follow.
Soldered? That may not be a good idea, depending on what you expect from the furnace. You're generally better served to weld, or use fasteners that can't fail when heated.
You have options with lining---it can be poured, or you can use a ramable lining. I highly recommend you invest in a commercial refractory, assuming you expect the furnace to perform well and be used reliably. No Portland cement should be used in furnace lining, for example, as it breaks down with heat. Refractories are formulated to perform at elevated temperatures, and generally contain no Portland cement.
4) Is it a good idea to use fiberglass outside of the steel furnace to help keeping heating process and spare fuel ?
My opinion? It's not a good idea to use fiber glass in the melting room, not for any reason. If you've ever seen a fiber glass fire, you'd understand. If you are concerned with heat loss, there are refractory linings that can be used to limit heat loss. You might consider pouring your lining in two layers, the outer one being a light weight refractory, intended to be used for insulation. The inner lining would be one that would tolerate the heat you intend to create. You can also wrap the exterior with an insulating blanket, once again, made from refractory products. They're readily available from foundry supply houses, refractory distributors. Check the yellow pages in your area for a supplier.

Be aware, refractory materials have a shelf life. Outdated materials may fail to cure properly, and will fail in use. Been there, done that.
If you intend to pour clean metals, avoid using a metallic melting vessel. If you insist on using metal, line the item with a refractory wash, to limit oxidation and contamination of the heat. The best scenario is to buy commercially made crucibles. If you limit, or avoid fluxing, they have a respectable life expectancy, and won't contaminate your heats.

Crucible furnaces are not known for their ability to pour cast iron, although some folks have enjoyed mixed success. If your goal is gray iron, I suggest you consider it carefully. Crucible furnaces are very good for non-ferrous materials, however.

Please do post a picture or two!

Welcome to the Chaski board.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

zappymax
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Joined: Wed Dec 26, 2012 6:59 pm

Re: top of furnace

Post by zappymax » Sat Dec 29, 2012 2:20 pm

trying to post some picts of previous stages, but even very small the server always replays " The image must be at least 0 pixels wide, 0 pixels high and at most 1024 pixels wide and 1024 pixels high. The submitted image is 2448 pixels wide and 3264 pixels high.". Could be a problem between apple and (your) windows server ?

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: top of furnace

Post by Harold_V » Sat Dec 29, 2012 3:37 pm

zappymax wrote:trying to post some picts of previous stages, but even very small the server always replays " The image must be at least 0 pixels wide, 0 pixels high and at most 1024 pixels wide and 1024 pixels high. The submitted image is 2448 pixels wide and 3264 pixels high.". Could be a problem between apple and (your) windows server ?
No problem with the server. Your pictures are just too large, and there's no reason they need to be.
Shrink them so they maximum size falls within those guidelines and they'll be accepted. If you don't have a good photo managing software, here's a link to IrfanView. It's a free download--and easy to use.
http://www.irfanview.com/

If you link them to the board, but have them stored elsewhere, make sure they're not wider than 800 pixels. If they are, I'll edit your post so they have to be clicked in order to be viewed. Pictures that are wider cause readers with older monitors to have to scroll side to side to read text, so I don't allow them on the board. The height of pictures doesn't create any issues, so we allow pictures that are up to 1024 pixels tall. Anything taller is most likely too wide, so they would have to be clicked to be viewed, too.

When posting pictures, consider that some folks are on a dial-up, so a picture of the size you mentioned is most likely so large in file size that, for them, it is impossible to view. The net result is that your thread may be ignored, so you risk losing valuable input from others who may be very knowledgeable, but unable to share what they know because they can't read the thread.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

zappymax
Posts: 5
Joined: Wed Dec 26, 2012 6:59 pm

Re: top of furnace

Post by zappymax » Tue Jan 01, 2013 7:24 pm

Hil Happy new year !

The picts are actually small (abt 300 kbs) and apparently no way to make those smaller... do you mean your server only accepts 30 o 25 kbs picts ?

Furnace is now running, details of position/angle of Venturi already modified, and gases control now is in process. Aluminium ingot just obtained in a metal crucible with top. Air compressor used, but another option will be considered, as actual compressor is noisy and the other is in repair. Movies are available, but donno if could be uploaded.

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: top of furnace

Post by Harold_V » Wed Jan 02, 2013 1:41 am

zappymax wrote:Hil Happy new year !

The picts are actually small (abt 300 kbs) and apparently no way to make those smaller... do you mean your server only accepts 30 o 25 kbs picts ?
A Happy New Year to you, too!

Smaller isn't shrinking file size, it's changing pixel count, which is what the board is telling you to do. Doesn't matter how small you make the file size if the pictures are too wide, which yours are. The maximum size is 1,024 pixels in width, with anything larger being rejected. Even those will be resized to a decent sized thumbnail (by the software), which can then be clicked to be viewed larger. We had to put limits on pictures because some individuals were posting pictures that were thousands of pixels in width, and several MB in file size. That creates no end to potential problems for the owner of the board. It's all related to reader inconvenience and limits in regards to servers.

Did you explore the link I provided? It has all of the required features to convert your pictures so they'll be acceptable.

File size, too, should be a consideration. You can post perfectly acceptable pictures of a file size no greater than 100 kb in size, assuming you shrink them first. Simply reducing pixel count lowers the demand for large file size, so you can shrink pictures without loss of detail.

There are people on this board who are locked in to a dial-up connection. For them, a 300 kb file may be too large to conveniently download, so they may simply ignore your post. We have to cater to everyone here, and find it's far less inconvenient for one individual to resize his pictures than it is for readers to be inconvenienced every time they look at a thread. Another consideration is that it takes only one picture that is oversized (larger than 800 pixels in width) on any given page in a thread to spread text off the screen for all posts on the same page, for folks with older monitors. Many of our readers are retired folks, who may or may not have the funds at their disposal to buy the latest and greatest in the way of computer gear, so I make it a point to look out for their best interest.
Furnace is now running, details of position/angle of Venturi already modified, and gases control now is in process. Aluminium ingot just obtained in a metal crucible with top. Air compressor used, but another option will be considered, as actual compressor is noisy and the other is in repair.
I'd recommend you abandon the notion of using an air compressor. There is no need, and it makes little sense to have that piece of equipment be a part of your melting procedure.

While I have no experience with self aspirating burners, there are designs at your disposal that require no air, aside from that which they siphon in use. If you're just melting aluminum, I can't imagine one not serving your needs adequately. No additional noise, and no equipment in operation unnecessarily.
Movies are available, but donno if could be uploaded.
The board accepts YouTube presentations, so if that's what you have, sure, post the link. If what you have is not acceptable, the board will simply reject, just as it does with oversized pictures. No harm done.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

zappymax
Posts: 5
Joined: Wed Dec 26, 2012 6:59 pm

Re: top of furnace

Post by zappymax » Wed Jan 02, 2013 1:40 pm

hi again,
will check options to post correctly ! but reducing pixels count is not common for me, and "generally" servers for upload can adapt themselves the size from normally (600 kbs) sized uploaded jpg to their necessity of compression or reduction.

The aluminium was used just to check the process , the bronce melting is the next option .

The air siphoned normally with the gas LP intake works, but produces less power, apparently.

The positive pressure from a vacuum cleaner will be used too, but the actual system works apparently well , and with a portable air compressor the equipment is perfectly transportable if necessary. The furnace can be moved on steel wheels. This combination is just a little bit noisy (compressor) compared to a vacuum, but the furnace also is noisy.

if you need the link to a MOV, could we use dropbox to simplify the process ?

but I will look the upload option you mentioned.

Cheers, Pat.

zappymax
Posts: 5
Joined: Wed Dec 26, 2012 6:59 pm

Re: top of furnace

Post by zappymax » Wed Jan 02, 2013 2:14 pm

meanwhile you could have a look on the stuff through https://www.facebook.com/Infrart.

will try linking trough youtube too. cheers

Harold_V
Posts: 17696
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: top of furnace

Post by Harold_V » Wed Jan 02, 2013 4:12 pm

zappymax wrote:if you need the link to a MOV, could we use dropbox to simplify the process ?
Any link would be fine, assuming readers don't have to use a password or subscribe to view your offering. The information can be stored anywhere, so long as it is readily accessible. Just try to keep it user friendly, so folks don't have to jump several hurdles in order to share what you offer.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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