[Gasification] The addition of steam to gasifier beds

[andy schofield]

Dear Mr. Black,

  In the days of making blue water-gas, the temperatures must have swung 
widely between making very hydrogen-rich gas to almost putting the fires 
out. Each cycle must have passed ideal conditions where steady-state 
hydrogen-production would be possible  if the operators only had better 
instruments and valves.

  I understand your work is with fluidized-bed systems. Is there any rule of 
thumb with respect to pressure, temperature, type of fuel, fuel-moisture 
content, steam-flow into the bed, and of hydrogen-production you can tell us 
about, true of all gasifiers?

  Can all water-vapor from the fuel, and that admitted on purpose be 
dissociated in the gasifier?

Andy Schofield
Great Lakes Renewable Fuels



>Re - the addition of steam to gasifiers
>
>In larger gasifiers, where heat loss is not a significant factor in the
>energy balance, steam can be used to control reaction  temperature.
>
>By controlling the steam to air ratio, the heat released by the  exothermic
>(heat producing) oxidation reaction of carbon to carbon monoxide  could be
>balanced by the endothermic (requiring heat) reaction of carbon  with 
>steam.
>
>This produces a better carbon burn-out in charcoal  or coal gasifiers while
>it
>avoids problems associated with ash  sintering or melting.   It is usually
>not
>necessary in biomass  gasifiers, since biomass drying and pyrolysis both
>require heat.    Also the amount of charcoal produced after pyrolysis is
>much
>smaller than in  coal gasifiers.
>
>John
>
>
>
>First Dr. Anderson wrote posing the interesting question about Mr Hao's
>gasifiers:
>
>Does the "water gas reaction" (is that the correct  name?) going to come
>into play?  What are the gains of injecting the  steam?
>
>Finally Dr Reed Wrote in reply to [Stoves] FW: Steam into a 800 ?C  hot 
>fire
>burns stronger;is common known by firemen .  (Thomas Reed):

>Dear Jeff and All:

>The "Blue Watergas" process broke H2O down with water according to

>C + H2O ==> CO + H2

>Since the reaction is very endothermic, there were two vessels cycling back 
>and forth, one being blown with air to raise the temperature (and make CO) 
>and the other being blown with steam.  It was widely distributed for many 
>years.

>TOM REED

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/