Mechanical briquette press

[posterslo]

Dear Sirs,

we have bought a mechanical piston operated briquett press and we have a question regarding mechanical briquette presses, if anyone has any knowledge about them. We produce briquettes mainly from dryed oak wood, 8-10% kiln dryed.

The problem: we have a mechanical briquette press from a company Spaenex (Germany)... the output is 300-400kg/h and the power is 15kw. The problem is that the briquets are pressed but they get soft and break very easy.

Our theory is that the problem is something with the conic (tapared) die? The conic (tapered) die is maybe not the right shape, how should the die be like? The die must be smaller at the start and then bigger to the end? We habe so far made 2 dies but we didnt get the best results yet...

With best regards,

Nejc

 

[posterslo]

I ment bigger aht the start and smaller at the end...sorry

 

[Jabberwocky]

I'm having a hard time visualizing your request - can you post a simple diagram that shows your issue? Pictures always help!

 

[dvd]

Since the press is from Germany you need to use metric trees! I have heard of charcoal briquets being produced with a binder similar to clay. What does Spaenex recommend?

 

[btrueblood]

Based on the reference below, you may need to get the feed material drier, preferrably to 6%. See bottom of page 4.

http://www.fpl.fs.fed.us/documnts/fplrn/fplrn075.pdf

 

[hydtools]

How do you know you are getting sufficient pressure into the briquette form for oak? You may not be getting enough compaction to force the oak fibers to bind or enough temperature to bind the oak.

Were any answers to your question on the physics forum helpful?

Ted

 

[GregLocock]

I worked for a couple of years on a straw briquetting press. 15 kW is not very much, I doubt that you are getting the sawdust hot enough to bind properly. I also find it hard to believe that you could get 300 kg/h. What diameter are the briquettes? Is this an auger type compressor or a piston?

We used to heat and dry the straw.

Do you have adjustable jaws after the cone? these are used to control the back pressure in the machine. You need to tighten these up to improve the briquettes.







Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[posterslo]

thanks for your help, yes the problem is we cant finds anybody who knows exactly how the die must be, we know that it must be slightly tapered from start, but how much, for how long...etc...we tryed to contact companys who produce these maschines with no response yet....

the press goes from 200kg/h to 400kg/h, it depends on the materials, at the end there are pneumatic clamps(picture attached) to control the back pressuere of the briquette.

 

[posterslo]

heres the picture of the die, the diameter of the briquette is 50mm.The sawdust is kiln dryed 7-10%.

 

[arunmrao]

Perhaps you need to improve the green strength of the briquette and also use some solid lubricant to assist ejection.



I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
_____________________________________

 

[GregLocock]

My gut feel is to make the taper almost the full length of the die.

The wear at the piston end will control how small you can make that diameter.

Bear in mind that the first 15 minutes of any run is a bit dubious as things haven't got up to temperature. We used to add paraffin to the material during the warmup to prevent sticking, but it wrecked the briquettes of course.

Slightly off topic, how does your mention handle the precompression stage? Ours used an auger to feed material into a pair of jaws that then clamped together, then the piston pushed through from the end and rammed the material into the die.




Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[posterslo]

The maschine has a screw for feeding the material in front of the piston, theres where the pre-compresion takes place. Also the die has pre-heaters, for easy starting. I now have some contact with a manufacture of that kind of presses, i hope he can help with the problem.

With best regards.

Nejc

 

[ornerynorsk]

My father used to work with this process. Binders are often required, depending on the material feedstock. I would check and see what the mfr recommends, and if they can do a sample run for you at their facility to validate a "recipe".

 

[jkrogers]

is the die heated, this plasticizes the outer layer at 200-300c and seals the briquette from moisture, otherwise they soak up the moisture and fall apart