[Gasification] Fluidised bed reactor

Pannirselvam P.V pannirbr at gmail.com
Sat Nov 30 11:37:51 CST 2013 

Dear Tom , Thomas , Jim

   Tom  said
By injecting exhaust into the gasifier you are recycling a lot of inert gas
(CO2, N2) and very little heat

       If the engine  use pyrogas derived  syngas not much  c02 and less
No2c problems from combustion exhaust  gas  thus the out put c02  exhaust
can be sucessfly used upt0 30 porcent  recycling back both enegy and co2,
for gasification . more  than this amount  othewise there can  be co2 and
N2 build up ,rightly pointed out by tom  as there is closed loop via direct
c02v  with no purge

    The possibilty of integrated innovative  design  very urgent indeed ,
the closed  c02 to   co  looping via combustion and  chacoal gasification
.We believe that  the gasification of chacoal with exchaust gas can reduce
the c02 to c0.  both via indirect pyrlysis  one sucg as GEK gasifier   and
also  co2  and h2  chacoal  gasifiction as done   done well by recent DTU
 viking gasifier reactors  need futher study regarding energy integration.

  int his context milled charcoal cola with exhaust  co2 and steam  via
spouted or fluidezed bed  gasification can play key role to arrive at
practical technology . However c02 and c0 equilibrium temperature limited
one  , mass transfer and heat rnsfer problems  need to be understood before
one arrive practical  small sacle fluidized bed  gasifier.

    Tom know  well  than any other that  Brazilian ceramic bricks made low
cost  gasogen was very much pracical energy generator iduring second wor
lwar  even in remote place of Brazil, now chinese  doing  more work  with
low cost charcoal gasifier.The pyrogas economy , charcoal economy ,syngas
sofc fuel all very mature to become  reality to  decentralized bioenergy
small smart grid   power.Inthis context  pyrolysis reactor as weel spouted
bed gasification can  make possible  the smaal biopower competetive with
large scale

   Yours sincerly with kind regards
   Pannirselvam P.V, Brasil


ᐧ

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On Sat, Nov 30, 2013 at 6:34 AM, Thomas Koch <tk at tke.dk> wrote:

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>
> Tom
>
> I agree very much to your description of the status of FB gasifiers.
> Not real upscaleable to an interesting size  - to many operations problems
> - too big carbon or thermal losses and too dirty gas to real interesting !
> The 2 Danish FB biomass gasifier - Pyroneer and Skive are struggling a
> real lot with gas cleaning.
>
> Do you have any idea of the status of the Viking gasifier development?
>
> I have asked several times if it is possible to visit the plant for over 2
> years - or if there is a public report available with a little data?? but
> no luck sofar.
>
> The last information I have from the project is from linked-in where saw
> that the only engineer I knew on the project have left  this summer.
>
> Best regards
>
> Thomas Koch
>
>
> -----Oprindelig meddelelse-----
> Fra: Gasification [mailto:gasification-bounces at lists.bioenergylists.org]
> På vegne af Tom Miles
> Sendt: 30. november 2013 07:01
> Til: 'Kevin'; 'Discussion of biomass pyrolysis and gasification'
> Emne: Re: [Gasification] Fluidised bed reactor
>
> If you want to use the engine exhaust in a gasifier you must consider the
> heat and material balance for a gasifier and IC engine.
>
> Fuel input 100%
> Heat loss in FB gasifier 5%
> (Sensible) Heat loss to cooling the gas 25% Cold clean gas efficiency to
> engine 70% (20% C0, 20% H2, 2% CH4, 12% CO2, 44% N).
> Heat conversion in engine ~25%
> 33% to power (~14-17% fuel to power)
> 33% to engine jacket heat (17% net)
> 33% to exhaust. (17% net, mostly CO2 and N)
>
> By injecting exhaust into the gasifier you are recycling a lot of inert
> gas (CO2, N2) and very little heat. The best use of the exhaust gas heat
> may be in preconditioning the fuel. Danish Technological University (DTU
> Viking gasifier, 1990-2010,  that is now being commercialized by Weiss) and
> later All Power Labs (Power Pallet, 2009) have used heat from the exhaust
> to indirectly dry and pyrolyze incoming fuel. The dried and partially
> devolatilized wood, along with preheated combustion air, appears to
> contribute to a stable oxidation zone. Both units make a very good quality
> gas. These are both fixed bed downdraft gasifiers with pre-pyrolysis zones.
> Peak temperatures reach 1000 C-1200 C in the oxidation zone and 800-900C
> in the reduction zones.
>
> http://www.btgworld.com/en/references/publications/handbook-biomass-gasifica
> tion-second-edition
>
> We have worked with many fluidized bed gasifiers in research and in
> industrial applications, for producer gas, and for synthesis gas. The
> fluidized bed is an intriguing reactor that has its use in industrial
> applications but they are expensive to build and operate.
>
> Fluidized bed (FB) gasifiers are unique because distributor plates or
> nozzles in the bed uniformly distribute the reactant (air, steam) in the
> sand (or media) bed. It is therefore imperative that the fuel be
> distributed uniformly for good gasification. This good distribution affords
> good temperature control as the fuel goes through the exo- and endo-
> thermic reactions that Kevin described. The ideal arrangement is to feed
> the fuel into the bed and allow sufficient time (depth) for it to
> completely react before breaking the surface into the vapor space above the
> bed. Of course there are variations on fluidized bed reactors such as
> spouted beds, fast beds, or entrained flow reactors. The latter are used
> for fast pyrolysis to liquid fuels by companies like Ensyn. I think that
> Dynamotive is the only company that uses a bubbling bed for pyrolysis. Many
> of the biomass to liquid reactors consumes the char to drive the process so
> there is no excess char
>
> When used for gasification fluidized beds can be pretty stable in the
> 650-750 C range. The higher temperatures are needed to provide thermal
> inertia when wetter fuel (>20% MC) is used. Higher temperatures are
> generated by adding oxidants as Kevin has described. Higher vapor space
> temperatures (750 C) can be achieved by adding air above the bed. The
> partial oxidation can reduce NOx precursors in the fuel gas. You can think
> of the heat balance as consuming between 25% and 33% of the fuel to convert
> the remainder to chemical (producer gas or syngas) and sensible energy.
> Producer gas is burned directly in a boiler or reformed for use in engines.
> Synthesis gas is usually made using enriched air or oxygen as the reactant
> or by indirect heating, as in a dual fluid bed. The variety of catalytic
> reformers used to make synthesis gases can be seen online in the
> presentations at the TC Biomass 2011 and 2013 conferences.
> http://www.gastechnology.org/tcbiomass2013/Pages/2013-Presentations.aspx
>
> There are a few small commercial (50-100 tpd) fluidized bed/entrained flow
> pyrolyzers that are making specialized products (liquid smoke) for the food
> industry. In general there are no commercial small scale fluidized bed
> gasifiers or combustors.
> Attempts by US boiler makers and several small entrepreneurs have failed
> to sustain commercial operation of fluidized bed gasifiers or combustors at
> the small scale.
>
> Tom  Miles
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org]
> On Behalf Of Kevin
> Sent: Friday, November 29, 2013 9:23 AM
> To: Discussion of biomass pyrolysis and gasification
> Subject: Re: [Gasification] Fluidised bed reactor
>
> Dear Rex
>
> ----- Original Message -----
> From: "Rex Zietsman" <rex at whitfieldfarm.co.za>
> To: <gasification at lists.bioenergylists.org>
> Sent: Friday, November 29, 2013 4:18 AM
> Subject: [Gasification] Fluidised bed reactor
>
>
> > Kevin,
> >
> > What you say is correct. However, there is benefit in returning some
> > exhaust
> > back to gasification as you force a higher production of CO relative to
> > CO2
> > production. I suspect it is an equilibrium thing...
>
> # For a gasifier having a relatively high exit temperature, then engine
> exhaust additions to the gasifier intake air could indeed be a way to both
> lower the gasifier exit temperature, and to raise the CO level.
>
> There is a CO/CO2 equilibrium consideration, and also a kinetics or "speed
> of reaction" consideration.
>
> Best wishes,
>
> Kevin
> >
> > Rex
> >
> >
> > ---
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> >
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