[Gasification] activated-carbon

[Peter Singfield]

Talking about fine tuned gasifiers ---

And this should cross over to the stove list -- in regards to their
discussion of adding some steam to the "burn" --

How about ending up with activated carbon char??

http://www.activated-carbon.com/1-2.html

Steam Activation

This technique is generally used for the activation of coal and coconut
shell raw material, which is usually processed in a carbonised form.
Activation is carried out at temperatures of 800 - 1100°C in the presence
of steam. 
Initially, gasification of the carbonised material with steam occurs; a
reaction known as the Water-Gas reaction:- 

C + H20 -> CO + H2 -175,440 kJ/(kg mol)

This reaction being endothermic, temperature is maintained by partial
burning of the CO and H2 formed:- 

2CO + O2 -> 2CO2 +393,790 kJ/(kg mol) 
2H2 + O2 -> 2H2O +396,650 kJ/(kg mol) 
 


The air is added so as to burn the gases without burning the carbon. 

The resultant activated carbon is graded, screened and de-dusted. 

Activated carbons produced by steam activation generally exhibit a 'fine'
pore structure, ideal for the adsorption of compounds from both the liquid
and vapour phase. 

CPL Carbon Link specialises in the use of steam activation for the
production of coconut shell and coal based activated carbons. 

Experience gained over many years of operation is used to ensure that
products are of uniform quality for consistent high performance

*************another interersting ref****************

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_ui
ds=16510239&dopt=Abstract

Preparation of steam activated carbon from rubberwood sawdust (Hevea
brasiliensis) and its adsorption kinetics.Prakash Kumar BG, Shivakamy K,
Miranda LR, Velan M. 
Department of Chemical Engineering, Alagappa College of Technology, Anna
University, Chennai 600025, India.

Activated carbon was produced from a biowaste product, rubberwood sawdust
(RWSD) using steam in a high temperature fluidized bed reactor. Experiments
were carried out to investigate the influence of various process parameters
such as activation time, activation temperature, particle size and
fluidising velocity on the quality of the activated carbon. The activated
carbon was characterized based on its iodine number, methylene blue number,
Brauner Emmet Teller (BET) surface area and surface area obtained using the
ethylene glycol mono ethyl ether (EGME) retention method. The best quality
activated carbon was obtained at an activation time and temperature of 1h
and 750 degrees C for an average particle size of 0.46 mm. The adsorption
kinetics shows that pseudo-second-order rate fitted the adsorption kinetics
better than pseudo-first-order rate equation. The adsorption capacity of
carbon produced from RWSD was found to be 1250 mg g(-1) for the Bismark
Brown dye. The rate constant and diffusion coefficient for intraparticle
transport were determined for steam activated carbon. The characteristic of
the prepared activated carbon was found comparable to the commercial
activated carbon.

PMID: 16510239 [PubMed - in process]

Full link for entire paper -- from 

 J Hazard Mater. 2006 Aug 25;136(3):922-9. Epub 2006 Feb 28

http://linkinghub.elsevier.com/retrieve/pii/S0304-3894(06)00050-1