[Stoves] [biochar] Gasifier stove grant (and semi-gasifiers)

Kevin kchisholm at ca.inter.net
Wed Oct 31 21:50:44 CDT 2012


  

Dear Paul


  ----- Original Message ----- 
  From: Paul Anderson 
  To: Discussion of biomass cooking stoves ; biochar at yahoogroups.com 
  Sent: Tuesday, October 30, 2012 4:05 PM
  Subject: [biochar] Gasifier stove grant (and semi-gasifiers)


    
  Stovers, and Gasifier folks,

  Let's give a big round of applause to Colorado State University and also to Envirofit for their strong entry into the world of gasifier cookstoves!!!

  One million dollars worth of encouragement for a strong entry is fantastic.   Congratulations.   Details are at:



  http://www.news.colostate.edu/Release/6485


  # Interesting article!

  The press release states:

    "It [semi-gasifier] separates the combustion process into two phases. In the first phase, combustible gasses are released from solid biomass. In the second phase, those combustible gasses are mixed with air and create a secondary flame," Tryner said.

  I think that definition is a good one for "gasifiers" and is certainly how the term has been used for a decade and more regarding cooking stoves.  

  # I would suggest that a good definition of a "Gasifier" is as follows:
  Gasifier: A Gasifier is a device for converting a solid or liquid fuel into a fuel gas.

  # There are three main types of "Gasifiers":
  1: Retort:  A fuel placed in a sealed vessle, with no access to oxygen, and heated with an external source of heat can yield  "pyrolysis gases" that can be captured and led away for chemical recovery, purification, for use as a fuel gas elsewhere, etc.  
  2: Air Blown Gasifier: Air/oxygen is contacted with a solid fuel at a temperature above its ignition point, to initiate pyrolysis and combustion, in the "Reaction Zone", and  CO2 and H2O in partially combusted gases are reduced back to CO and H2 by incandescent char in the "Reaction Zone", leaving little to no residual charcoal. An "Air Blown Gasifier" can be characterized by the intentional supply of only "Primary Air", for gasification of the fuel, and with none of the air supplied leaving the gasifier as "products of intended combustion. "
  3: Semi-Gasifier: A "Semi-Gasifier" is identical to an "Air Blown Gasifier", EXCEPT that by design,  or by operation, it leaves a significant portion of its initial carbon content as an ungasifier char residue.

  #  A"Gasifier" differs fundamentally from a "Combustor", where a fuel is burned to completion. A "Combustor" can be easily distinguished from a "Gasifier" by the presence of "purposefully added provision for the introduction of secondary air, to a fuel gas intended for combustion to completion." 

  So I will ask the first question:    

  Please define the difference between a "semi-gasifier" and a "gasifier" in the terminology used by CSU.   (I hope you just drop the "semi-" part.)

  # The difference between a "Gasifier" and a "Semi-Gasifier" is that a "Gasifier" converts substantially all the fuel provided into a gas, while a "Semi-Gasifier" converts only part of the supplied fuel to a gas, and leaves behind a significant portion of the carbon energy content of the initial fuel as char which was not gasified..

  # Following is a copy of a picture from the website:
   http://www.news.colostate.edu/content/photos/Semi%20gasifier%20schematic.jpg



  # This is puzzling... they term their device a "Semi-Gasifier Stove", yet 
  1: It is NOT a semi-gasifier, in that neither in the schematic, nor in their website text, do they acknowledge the production of char.
  2: There is clear provision of "secondary air" for the intended combustion of the products of gasification, ie, it is a "combustor". (or stove.)
  It should more properly be termed a "Gasifier Stove" in that all the fuel is gasified, with no residual char.

  # On the other hand, a TLUD is clearly a "Semi-Gasifier Combustor" (Stove), in that 
  1: A significant portion of the supplied fuel leaves the system as char
  2: There is definite provision for the introduction of secondary air, to burn the products of gasification to completion.

  The folks at CSU do GREAT work, and I am sure that their entry into this aspect of improved cookstoves will result is some great benefits.

  # I must be missing something here, but aren't they simply re-inventing the pellet stove?"

  Best wishes,

  Kevin

  Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

  -------- Original Message -------- 
        Subject:  Re: you and Hugh and biochar 
        Date:  Tue, 30 Oct 2012 08:23:21 -0600 
        From:  John Field <john.l.field at gmail.com> 
        To:  Paul Anderson <psanders at ilstu.edu> 
        CC:  Hugh McLaughlin <wastemin1 at verizon.net> 





  However, the general consensus is that only forced-draft gasifier cookstoves deliver remarkably low emissions, whereas natural draft gasifiers tend to be similar or only marginal better than most rocket stove designs.  This is an impression reinforced by my own (very limited) work, as well as by the attached recent paper by Abishek Kar of the Surya project.  In contrast, the recent paper by Jim Jetter's group is more difficult to interpret, and includes a natural draft gasifier with better high-performance emissions than all other stoves tested, as well as a forced-draft gasifier among the worst performers.  Go figure!






  On Mon, Oct 29, 2012 at 5:35 PM, John Field <john.l.field at gmail.com> wrote:

    Apologies for the lack of communication here- I was away all last week at the ASA-SSSA-CSSA conference.  No new stoves/biochar news at the moment; I'm totally preoccupied preparing for my prelim exam for the next several weeks.  

    Hope you well,
    john 






    On Mon, Oct 29, 2012 at 5:05 PM, Paul Anderson <psanders at ilstu.edu> wrote:

      John,

      Sorry that you and Hugh did not meet when he was in Boulder last week.

      Are there any more developments involving you and stoves and biochar?

      Doc

      -- 
      Paul S. Anderson, PhD  aka "Dr TLUD"
      Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
      Website:  www.drtlud.com






    -- 
    Thank you,
    John Field
    NSF IGERT Fellow, Multidisciplinary Approaches to Sustainable BioEnergy
    Department of Mechanical Engineering, Colorado State University

    email:  john.L.field at colostate.edu
    cell:  (317) 748-9792
    bioenergy-igert.colostate.edu
    bioenergyigert.wordpress.com





  -- 
  Thank you,
  John Field
  NSF IGERT Fellow, Multidisciplinary Approaches to Sustainable BioEnergy
  Department of Mechanical Engineering, Colorado State University

  email:  john.L.field at colostate.edu
  cell:  (317) 748-9792
  bioenergy-igert.colostate.edu
  bioenergyigert.wordpress.com








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