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Author Topic: Exploding Sawdust  (Read 9346 times)

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Offline Ianab

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Re: Exploding Sawdust
« Reply #20 on: January 22, 2004, 01:02:52 PM »
Have come across this effect a few times, and it's pretty safe to experiment throwing a handfull of dry sawdust on a rubbish fire. But stand back cos it will probably make a little fireball. As others have said, the effect gets bigger fast  :o
A bucketfull will remove your eyebrows and as Buzz says, a sackfull in an enclosed place would be a major explosion.
Had an incident at work here where a customer emptied waste photocopier toner onto a rubbish fire. This is made of very fine plastic powder and carbon black  :o Results looked a lot worse than they actually were because of the carbon black, but it took a while for the kids eyebrows to grow back.

Be safe out there

Ian
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Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #21 on: January 23, 2004, 04:18:41 AM »
   Buzz sawyer, your link was missing. (I mean that in a nice way. Some days my link is not only missing, but I suspect I am the missing link..)

  I did the 'pinch' of material test, using cedar shavings that were very dry (supposedly)- grinding them as fine as I could- the results were sparkly but not impressive. Then I tried a pinch of flour and the reaction was more complete and brisk. I think particle size is critical. I bet sanding would give a finer material to start.

  Thanks, Ian, for the quantitative estimates.

  I cannot IMAGINE the copier powder reaction- that stuff is ultrafine.

  Buzzsawyer- I do want to read about the sawdust vortex furnaces- that sounds like the application I was wondering about. I'm not a bit surprised if someone already thought of it, tried it, and it worked. The commercial breakpoint would be in the handling and the costs of preparation as compared to burning the rregular stuff as it comes from the tree- or the pelleted sawdust .  I will do a web search on sawdust vortex furnaces but if you have a link that wouild be kewl to read.  lw
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #22 on: January 23, 2004, 04:46:29 AM »
   OK, yes there is plenty online. www.shirleyassociation.com/history_of_drummond.htm is kinda cute, if only a peripheral mention of it. Talks about 1400*C temperatures and corrosive exhaust gases.

www.eabioenergy-task32.com/overview/largescale.html gets more specific, and
www.fwc.com/publications/tech_papers/powgen/pdfs/DesignIssuesforCoFiringBiomass.pdf
really gets down to it, showing BTUs for wood dust as compared to some of the coal dusts (check out the names for the coal dust..) and implies that while the btu is less, the corrosive components to be removed from exhaust gases are also less. Getting low on coal dust? Bleed in a little sawdust.

  I don't think they'll be making one that will run my car, somehow. There were a few sites talking about H2 production from wood via pyrolysis- I guess that could go into a fuel cell.  lw
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #23 on: January 23, 2004, 04:54:11 AM »
   That 2nd link should be
www.ieabioenergy-task32.com/overview/largescale.html  

  lw
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline Duane_Moore

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Re: Exploding Sawdust
« Reply #24 on: February 08, 2004, 12:02:13 AM »
 :-[ found a no-no- was working on a hot rod today on the brakes, grandson showed up to help.....4yrs old.... anyway he spilled the brake fluid. so I kinda wiped it up before Grandma caught up. then Grandma cleaned it up good..... she got the Beach out...no-no-no-....do not mix bleach and brake fluid as we found out....Smoke and lots of it... I mean Lots...  won't do that one again.... Duh---Duane :-[
village Idiot---   the cat fixers----  I am not a complete Idiot. some parts missing.

Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #25 on: February 08, 2004, 03:24:15 PM »
   Bleach and brake fluid!!?? Who knew? Now I gotta finger that one out.. lw
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline PatrickG

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Re: Exploding Sawdust
« Reply #26 on: February 22, 2004, 07:42:58 AM »
 :) Bleach and brake fluid... There are lots of "home" chemicals that are generally safe to use but can be dangerous when mixed.  Bleach can give off chlorine gas when mixed with the wrong stuff.  I choose to not elaborate here but trust me there are lots of wrong combinations.

See also: "Anarchist's Cookbook"

Now then back to the topic... dust explosions.  A Jr. Highschool science demonstration to illustrate the danger of dust goes like this...

Required materials:

1. A closed container, don't use a compression lid (paint can style) as it will explode too violently. A large metal can with friction fit lid like you see for potato chips and such is good.
1.1  OK you can use a 5 gal can with a compression lid but for goodness sakes do it outside away from windows and anytihing that a flying lid might damage.  After you understand the process, ask yourself how you will safely get the large compression lid on the can withought risk.  Some folks have hust layed a piece of plywood over the can.  Beware exploding seams!

2. a few feet (3-10) of flexible tubing (plastic, rubber, I don't recommend garden hose or large diameter tubing if you detonate by blowing by mouth)
2.1  You can use a shop air hose instead of blowing by mouth.

3. a candle

4. A few teaspoons of plain white wheat flour or extremely fine sanding dust.

Assembly directions:  Punch a hole in the bottom of the can near one side not near the center (About half the diameter of the large end of the funel from the sidewall.) It should be a snug fit to the tubing. Insert the tubing through the hole and insert the small end of the funnel into the tubing.  You want a tight fit between funnel and tube. With a little fussing you can make the tube fit tightly to the hole in the can and to the funnel.

Place a couple teaspoons of regular flour (not Bisquick or other baking mix but plain white flour OR alternatively sanding dust from sanding wood) into the funnel.

Place the can on a table or workbench or better yet on a chair located outside.  

A. Put on your hearing protection

(The rest of these instructions are to be performed in rapid succession.)

B. Place a lighted candle inside the can on the side opposite the funnel.

C. Place the lid securely on the can without bumping the can much or allowing your head to be over the top of the can.

D. Hunker down with your head under the chair (or whatever is supporting the can)

E. Blow sharply into the tube.

Expected results:  Relatively violent explosion that may rupture the side seam of the metal can and will likely shoot the lid to quite a height.

This used to be a relatively common demonstration of a dust explosion.  Of course, coal dust, fine sawdust, or whatever burnable substance can be substituted.  The finer the fuel dust the more violent the explosion. Finer fuel gives more surface area in contact with atmospheric oxygen and a faster burn rate per unit weight of fuel.

When I was in the USAF a Senior Master Sgt special ordered "Electrical Safety Shoes" for everyone in the Training Devices Section" flight simulators and such.  We worked around dangerous voltages.  Everyone was trying on their new safety shoes but I read the labels and instructions in the shoe box first.  There were instructions on how to measure the conductivity of the shoes to ensure they were operable.  Another sticker went on say how they met bureau of mines specification such and such.  Well my little light came on to a dim glow as I realized that THESE ELECTRICAL SAFETY SHOES were built for the purpose of grounding the wearer to prevent the build up of static charges that could set off an explosion in a mine, grain elevator, spray booth, flour mill, gun powder or explosives plant or wherever explosive or highly combustable products were handled.  

Unfortunately we needed shoes to insulate us from ground not directly connect us to it.  These shoes could have got one of us killed.  I did a slightly unprofessional thing like shouting. "Sgt. Mc Bride, you idiot, you're going to get us killed" as I threw the shoes about 50 ft in his direction.  To save face at base supply he refused to return the shoes.  He told veryone to take them home and wear them to work on their cars or something where the steel toes would make you safe.

8) 8)   Pat    8) 8)

Offline Buzz-sawyer

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Re: Exploding Sawdust
« Reply #27 on: February 22, 2004, 08:25:20 AM »
LW
You remind me of me.....with all the curiosity and experimentation.....have you studied wood gasification...that will run your car!!!! people were doin it 60 years ago .....
    HEAR THAT BLADE SING!

Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #28 on: February 23, 2004, 03:11:52 PM »
   no, I haven't seen that- I've seen propane cars. Is it like that- gasify, collect in a tank etc- or do ya load a few chunksa wood inta the hopper and drive off?  lw
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline L. Wakefield

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Re: Exploding Sawdust
« Reply #29 on: February 23, 2004, 03:15:50 PM »
Quote


snip

2. a few feet (3-10) of flexible tubing (plastic, rubber, I don't recommend garden hose or large diameter tubing if you detonate by blowing by mouth)
2.1  You can use a shop air hose instead of blowing by mouth.

snip



  I'm a mite skeered of that one- whatever you do, don't inhale!   :D :D :D
L. Wakefield, owner and operator of the beastly truck Heretik, that refuses to stay between the lines when parking

Offline Hunter

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Re: Exploding Sawdust
« Reply #30 on: April 09, 2004, 08:09:52 PM »
One of my good friends works at a mill in Maine.
He is in the bagger house, bagging the shavings.
They have to be super catuios about the dust. all of there wood is dried and they get all the by products in there room. they have massive air movers and absolutly no open flames.
One guy did try to light a cigerette and the forman punched him in the mouth and asked him if he was wanting to kill them.
Needless to say, they have very strict rules and they dont take it lightly.
Hunter
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614-554-2169
Dolmar / Efco / Redmax / Silvey Grinders Sales



Offline james

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Re: Exploding Sawdust
« Reply #31 on: April 11, 2004, 09:45:21 AM »
its also refered to as a fuel-air explosive used by the military and for demolition :o

Offline sawguy21

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Re: Exploding Sawdust
« Reply #32 on: November 16, 2004, 06:20:50 PM »
Just about any fine dust suspended in the air is a recipe for a ka-boom. A co-worker was using corn starch in a media blasting cabinet. I heard a loud WHOOOMP and ran over to see him standing there, his gloved hands inside the cabinet and his eyes and mouth the size of hubcaps. He had bumped the light in the cabinet
Reminds me of Halloween when us kids bought calcium carbide at the local machine shop until they figgered out what we were doing with it but that's another story.
old age and treachery will always overcome youth and enthusiasm

Offline ksu_chainsaw

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Re: Exploding Sawdust
« Reply #33 on: November 17, 2004, 02:52:37 AM »
Thats the reason that grain elevators explode too.  When I was woking on them to repair them, we couldnt use a torch on the larger elevators because of the exlposion risk, and we had to wet down everything around the area we were working.  Seveal years ago, an elevator in the Witchita area exploded from a buildup of too much grain dust.

Charles

Offline Ianab

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Re: Exploding Sawdust
« Reply #34 on: November 17, 2004, 03:21:13 AM »
Not that I've been experimenting or anything...
but a cupfull of that really fine sawdust from the belt sander dust bag should only be thrown on the rubbish fire from a safe distance upwind... :D

Disclaimer... If You or any of your dumb buddys try this and loose your eyebrows... dont blame us

Another version is Milk Powder.. Dairy factory up north of here lost part of it's roof after a flash fire in stray powder.
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Offline sawguy21

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Re: Exploding Sawdust
« Reply #35 on: November 17, 2004, 05:56:18 AM »
Careful of them Darwin Awards. Don't want one.
old age and treachery will always overcome youth and enthusiasm


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