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Posted by barnstable1197 on November 27, 2006 at 23:13:02:
I am currently a control room operator of 2 200,000 lb an hr, balanced draft, pulverized coal fired boilers.These boilers provide process steam for a facility that constantly has load swings(40 to 50k in a matter of minutes). FD fans were always controlled by the trim setting(usually 4%o2). This worked well for several years with the ability to maintain o2 consistently + or - 1/5% of setpoint. Controls were upgraded and now the FD fan control is dominated by steam flow(so much so that the o2 meter can be taken out of service without a noticeable difference in o2) The problem is the o2 now swings between 3 and 7% with spikes down(maybe once every few hours) to as low as 1%.I am interested if many other facilities operate these type boilers with this FD fan control setup.
Thank You