RE: GAS-L: Torrefied-densified biomass

[Weststeijn A <A.Weststeijn@epz.nl>]

Dear Mr Reed,

Densification of biomass will be quite a relevant subject in the near future
for small systems as well as large.

Although CV's in the order of 20-23 MJ/kg for uncompressed torrefied biomass
constitute a substantial improvement even over pre-dried wood, generally
speaking there still remains the problem of lower specific volume. 

I.e. the question remains how to feed sufficient product into a system
designed for higher CV as well as for higher density fuel. Like in case of
cofiring biomass in a coal fired utility grade power plant. A clear
constraint for future truely high cofiring rates certainly is to be found in
the "volume transport" of the fuel supply system. I can imagine that this
applies to other systems, non-specificly designed for biomass conversion, as
well. The general trick to make biomass conversion pay here is: minimal
plant modification at maximal energy input per unit of volume.

So, densification may be part of the answer to technically allow for higher
cofiring rates. And economical densification, by lowering pelletizing power,
the more so. Not to mention bulk transportation cost reductions almost
proportional to reduced volume. Therefore, a combination of pelletizing and
torrefaction in my opinion is certainly worth while investigating. Also,
there may be other shapes for the pressed product than small pellets.
Please count me in to help develop data for cofiring.

Best regards,
Andries Weststeijn
EPZ
Netherlands

> ----------
> Van: 	Reedtb2@cs.com[SMTP:Reedtb2@cs.com]
> Antwoord naar: 	gasification@crest.org
> Verzonden: 	dinsdag 9 januari 2001 14:21
> Aan: 	gasification@crest.org
> CC: 	Stoves@crest.org; bioenergy@crest.org
> Onderwerp: 	GAS-L: Torrefied-densified biomass
> 
> Dear All: 
> 
> The widespread use of biomass energy depends on a convenient supply of
> large 
> quantities of biomass.  Densification can help with this because it makes 
> many kinds of waste into a very acceptable - desirable fuel.  Gasifiers, 
> pellet stoves and woodgas stoves all benefit from using densified wood.   
> 
> In 1979 we found in static tests on pelletizing that 
> 
> Preheating reduced the needed pressure required by a factor of 2 
> 
> Energy for densification was also reduced by a factor of 2 at 225 C 
> 
> The energy content of the resulting pellets rose from 19.3 kJ/g at room 
> temperature to 21.4 kJ/g at 225 C (23.0) at 250 C) 
> 
> ["Biomass Densification Energy Requirements", T. Reed, G. Trezek, and L. 
> Diaz, in Thermal Conversion of Solid Wastes", J. L. Jones and S. B.
> Radding, 
> ACS Symposium Series 130, Was. D.C., 1980.  I still have the pellets in my
> 
> "museum".] 
> 
> In a recent article the Asian Institute of Technology found significantly 
> reduced energy and die wear from preheating biomass before pelletizing.   
>                                                       ~~~~~ 
> 
> Now (1982 actually) comes torrefied wood, (wood roasted at 200-250 C to 
> remove primarily water and CO2, leaving a higher energy content and, lower
> 
> mass for shipping).   
> 
> The next obvious step would be to combine the two processes, Torrefying
> the 
> wood and then immediately densifying it while it is hot and weak, thus 
> compounding the benefits of both processes.   
> 
> If anyone is interested in pursuing this I would be happy to cooperate
> with 
> them.   
> 
> In a message dated 12/19/00 8:41:32 AM Mountain Standard Time, 
> heat-win@cwcom.net writes: 
> 
> 
> 
> 
> 
> 	Dear All, 
> 
> 	In connection with greenhouses you will find much interesting 
> 	information re. charcoal and torrefied wood at . 
> 
> 	If for example tomatoes are being grown, the vines left over can be 
> 	torrefied and used to fuel the greenhouse heating. If there aren't 
> 	enough, then other renewable fuels such as wood pellets can be used.
> 
> 
> 	Regarding the lime kilns, have a look at , in 
> 	particular the RofireTM link you will find there. Cement kilns are
> now 
> 	being heated using RofireTM pellets made from the un-reusable
> fibres, 
> 	plastic, etc, left over from the recycling of paper. 
> 
> 	Whatever else you do to counter the natural gas and oil price
> crises, 
> 	please go out and plant more trees! 
> 
> 	Regards, 
> 
> 	Thomas J Stubbing 
> 
> 
> 	John Flottvik wrote: 
> 
> 
> 
> 
> 
> 
> Thomas B. Reed 
> President - The Biomass Energy Foundation 
> 1810 Smith Rd., Golden, CO 80401 
> Reedtb2@cs.com;  303 278 0558 
> 
> Research Director, 
> The Community Power Corporation, 
> 8420 S. Continental Divide Rd. 
> Littleton, CO 80127 
> 303 933 3135
> 

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