[Gasification] mycoremediation of tarry water

Kevin kchisholm at ca.inter.net
Sun Feb 3 14:18:23 CST 2013


Dear Craig
  ----- Original Message ----- 
  From: Craig Kernan 
  To: gasification at lists.bioenergylists.org 
  Sent: Sunday, February 03, 2013 2:32 PM
  Subject: Re: [Gasification] mycoremediation of tarry water


  Some possibly naieve questions a bit outside the box::

  # Sometimes, seemingly naieve questions can be profoundly complex. :-)

  I assume we are considering mostly the cleanup of filters and equipment.

  # No... in the first instance, the problem is to get the "tar aerosols" out of the gas. A high percentage of them stay suspended in the water for a period of time, but over a period of time, some can settle out, or stick to container sidewalls. Others coat the inside of the gas/water contacting system and build up. Tars falling out of a water solution are not soluble, (or are of very limited solubility)  in water.   

  Can the chemical energy in these compounds be used in another process? 

  # It can always be burned, but with difficulty. Perhaps the simplest alternative is to scrape it off the equipment, and then recycle back to the gasifier, as a small percentage of the gasifier feed.

  Is water the only solvent that can be used?   (e.g. vegatable oil? .... )

  # The best thing to do is to try solvents available and afffordable to you and see what works. I have tried naphtha, furnace oil, and cooking oil with very limited success.

  Can the tars be captured is such a way as to become a useful fuel?  (e.g. fiber filters processed to? .... ) 

  # Dry wood chips and sawdust will filter some of the tars and dusts, and will absorb moisture from the gas. If such chips are dried, they can be fed back into a gasifier. Sawdust might be formable into bricks, or briquettes, and then used as fuel for a fire. 
  Best wishes,

  Kevin

  Craig

                       



  On 2/3/2013 9:50 AM, Kevin wrote:

    Dear Stuart
      ----- Original Message ----- 
      From: stuart mather 
      To: Kevin C ; gasification at lists.bioenergylists.org 
      Sent: Saturday, February 02, 2013 8:17 PM
      Subject: Re: [Gasification] mycoremediation of tarry water







--------------------------------------------------------------------------
      From: Kevin C <kchisholm at ca.inter.net>
      To: stuart mather <kneebraceboy at yahoo.com.au>; Discussion of biomass pyrolysis and gasification <gasification at lists.bioenergylists.org> 
      Sent: Saturday, 2 February 2013 2:50 PM
      Subject: Re: [Gasification] mycoremediation of tarry water



      Kevin wrote:
       ....While I have not seen a report showing that blackwater disposal is harmful to the environment, I have not seen one that says it is not harmful either. However, a competent Gasifier Operator sent me pictures of his blackwater dump site a few years after he stopped dumping blackwater there, and the plants growing there seemed just as vigorous and healthy as nearby plants outside teh dump zone.
      > 
      > Best wishes,
      > 
      > Kevin
       
      That's intriguing Kevin,
      So I wonder why there seems to be a general consensus that dumping tarry water in a pond amounts to environmental vandalism. Not saying your gasifier correspondent was making it up. But you would think the President of Myanmar would have better things to do than declare black water gasification leach ponds toxic sites  Military juntas aren't well known for their environmental awareness. So why the concern about tar ponds people?
      Stuart.

      # A "Tar Pond" or "Blackwater Disposal Pond" is a highly concentrated "disposal situation". Too much of anything is almost certain to be a problem. One cannot grow carrots or wheat in a pond used to dispose of distilled water, and ethanol alcohol is a poison when taken in excess quantities at high concentrations, as an extreme examples. The issues here are one of both toxicity and concentration. A "Gasifier Tarpond" could indeed become qualified as a 'superfund site." However, the same chemicals, if spread in dilute form over say 1, or 10, or 100 square miles may present no significant hazard, and may even yiled a net benefit. 

      # I would say intuitively that there is a combination of "toxicity and concentration" above which, gasifire tar disposal is "bad", and that there are "toxicity and concentration" combinations below which gasifier tars are not hazardous, and may even be beneficial. I don't know all the compounds in gasifier tars, and the concentrations below which they can be "generally considered as safe." In my opinion, nobody can responsibly say for certain that "gasifier tars are toxic" unless one specifies both the components and concentration. Neither can anyone say for certain that  "gasifier tars are safe" unless one has a rational data base to support the statement. 

      # The process of smoking fish, meat, and other food products can be looked on as a way to dispose of "gasifier tars." :-) The fact that such "smoke tars" preserve foods proves that such tars are toxic to some life-forms. Some studies suggest that smoked foods are bad, while others suggest that while there may be some "cancer deaths" as a result of eating such smoked foods, the benefits from reducing deaths from pathogenic organisms that would otherwise be present greatly exceed the "smoking detriments."

      # "The way to eliminate the gasifier tar problem is to eliminate tar formation in the first place." This is not that difficult with properly designed and operated gasifiers. This can be done, as is evidenced by the many gasifiers in operation fueling IC engines, with no tar problems. Stratified downdraft gasifiers, and updraft gasifiers are well known as "tarry gas producers." In some applications, such gasifier systems can be very appropriate, because of their generally lower capital cost, and their ability to handle a wider range of fuel sizing and moisture content. Such gases can often be burned directly, without need for tar removal. TLUD stoves, which are basically "an updraft gasifier with a build-in burner to destroy the tars" are an excellent example of a gasification system where tarry gas is not a problem. If one wants to pipe such gas to a burner at a distance from the gasifier, then tar build-up in piping is likely to be a problem. Water quenching of such gas will remove many of the tars, ash and char that cause pipes to plug. Then one has the problem and cost of dealing with the "blackwater." If the problem, and cost of dealing with it are big enough, then it may be better to employ a different gasifier, and different fuel preparation techniques, to produce a gas with an acceptable tar level. 

      Best wishes,

      Kevin



     

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