Why the Burn Box is our Friend

Ted Berg tberg at snf.stanford.edu
Wed Nov 20 13:52:49 PST 2002


Greetings all,
    As some or all of you might know the tools listed all go to one
CDO(BurnBox), The job of the burn box is to take whatever nasty stuff we
run in the furnaces, that does not react to make our desired film, and
break it down to a water soluable by-product.  This is a tough job for
our friend the burn box especially if we run 14:1 DCS to NH3 ratio where
a large amount of gas goes unreacted. In normal operation just a slight
amount of excess gas enters the burn box which runs at 850 degrees C and
it is burned.  This by-product is then washed down with a spray of water
to acid waste.  What has happened recently is that too much gas is
entering the burn box andthe by-product mostly silicon dioxide and maybe
some ammonium chloride and throw in a bit of oil mist from the pumps is
building up so fast we are forced to tear the burn box nearly every day
or the back pressure becomes too high.
    Which brings us to point B.  We have reserved a short window of time
every day between 6:00am and 8:00am.  This allows us to cool the burn
box and clean it.  We would really appreciate it if users could be
finished or at least in cool down by 6:00 am.
    Last point, Next week we will have 4 days of Holiday.  Users need to
be aware of burn box pressure and not run if pressure is above 3" H2O.
Thanks for your help in advance.ted




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