Re: Bag house?

["Sam McClintock" <scmcclintock@ipass.net>]

  > From: Alan Watson <alanwatson@gn.apc.org>
  > ..and they sometimes burst, or catch fire, dumping a large part 
  > of their contents into the neighbouring environment.  Also in 
  > some UK MSW incinerators the old bags are burned on site even 
  > though they are hazardous (special) wastes. 
  
  Having been present at a particularly nasty baghouse fire, I can
  confirm Mr. Watson's observation.  Though I don't think he has quite
  caught the true picture when a large baghouse catches fire - the huge
  cloud of dust and smoke, 100% dense, traffic coming to a complete
  standstill because you can't see more than 25 yards, people downwind
  panicking because they have no idea where the cloud started, the first
  tenuous minutes as the fire fighters and facility workers try to figure
  out if the flames will spread or not, hospitals start to fill up as
  people have coughing fits and trouble breathing . . .   It may only
  take ten minutes for the worst of it to pass, but it can be a real bad
  ten minutes.
  
  ON THE OTHER HAND, the majority of baghouse applications are very
  innocuous, harmless, and do exactly what they are designed for, the
  capture of particulate material.  Lime injection can be used prior to
  the baghouse, with the baghouse capturing excess lime and the reacted
  acid components very effectively.  Properly designed and maintained
  baghouses last for decades; all types of bags are designed for various
  applications and temperatures.  Baghouses are normally engineered so
  that part of the structure can have problems and be serviced for
  maintenance without significantly impacting its collection abilities.  
  
  It is not a cure for all sources, though.  A cement kiln is a good
  example - the baghouse will collect a large amount of particulate
  (99+%), but the 1000+ tons of NOx compounds produced by the kiln each
  year will pass right through it.  Some dioxins will be caught as
  particulate material, but a lot will just pass right on through as a
  gaseous phase into the atmosphere.  In these cases you either have to
  add material to the baghouse, design additional control technology to
  be used in conjunction with the baghouse, or change the process so as
  not to provide a challenge for the baghouse.
  
  
  Sam McClintock
  scmcclintock@ipass.net