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Posted by Paul James on March 07, 2008 at 13:47:56:
In Reply to: drum level shrink and swell posted by barnstable1197 on January 24, 2008 at 22:57:27:
: Your feed control system probably consists of three element feed system. I have experienced problems in past with clogged pipe nipples that feed transmitters. First, constant leg on drum level (TOP) may be partially blocked. Also, steam flow may be cloggeds sending erroneous signals to DCS. Just a thought.
: I operate a large industrial coal fired boiler. In the past when we experienced large steam load swings the boiler drum level would go up or down a couple of inches off setpoint due to shrink and swell. Within minutes we would be back at setpoint. It seems now that with the same amount of steam load swings the drum level goes up or down as much as 7 inches off setpoint due to shrink and swell. The controls still manage to get back to setpoint in a timely fashion. My question is:What could cause the amount of shrink and swell to change on a boiler,if in fact it can change?