[Gasification] Empirical data on dryer systems

[Rodenhuis, E.J. (Erik Jan, Student TBK)]

Hey all!

Is this topic not worth considering a thought? I hoped to get some get
some ideas and figures about dryers. Couldn't find much discussion on
this topic in the archives Or do you just not have a clue ;-)

Erik

-----Oorspronkelijk bericht-----
Van: gasification-bounces at listserv.repp.org
[mailto:gasification-bounces at listserv.repp.org] Namens Rodenhuis, E.J.
(Erik Jan,Student TBK)
Verzonden: donderdag 7 december 2006 13:46
Aan: gasification at listserv.repp.org
Onderwerp: [Gasification] Empirical data on dryer systems

Dear list,

 

For downdraught gasification of biomass generally is assumed that the
moisture content of the biomass is below 15% (wb). As the moisture
content of green wood is mostly higher and I have seen sawmills use
water-cooled band saws, you need to dry the wood waste before it is
suitable to gasify. Main options seem to be drum drying of flash/ring
drying.

 

Drum Drying:

-        Co-current to reduce fire hazard

-        Tair,in = 230 - 1100 degr. Celsius

-        Tair, out = 70 - 110 degr. Celsius

-        Empirical data on energy consumption 5 - 12 GJ/ton of water
evaporated, see poster presentation Mani:
http://www.biocap.ca/images/pdfs/conferencePosters/Mani_S_P1.pdf

-        General statements made in diverse publications: "high"
investment cost, "low energy use"

 

 Flash Drying

-        short residence time < 30 sec

-        drying at lower temperatures Tair,in = 100 - 650 degr Celsius

-        "low investment, high energy use"

 

A few other systems available:
http://barr-rosin.com/english/pdf/airstream.pdf 

 

As we have will have with a downdraught gasifier with an ic-engine some
low quality waste energy streams are available, namely from gas cooling
(gas-gas shell-and-tube heat exchanger) and from the exhaust gases, I am
interested to know what the general ideas about which drying system
suits best. There might be some other criteria like the controllability
of the process and fire hazards.

 

Maybe there is somebody who can give some rule of thumb for investment
cost and energy consumption of a 1 ton/h drying system. When assuming
that we want to dry the wood waste (let's assume chips) from MCwet 30%
to a moisture content of 15% we need to evaporate 115 kg H2O/h.

 

Any hints or leads to good literature on the web on this topic??

 

Regards,

 

Erik Jan Rodenhuis 

_______________________________________________
Gasification mailing list
Gasification at listserv.repp.org
http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
http://www.repp.org/discussiongroups/resources/gasification