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Posted by Bob D. on September 17, 2004 at 07:39:06:
In Reply to: Economizer posted by Prabakaran on September 16, 2004 at 09:34:16:
It a little difficult to tell without a lot more information, such as the size of the boiler, the fuel, operating conditions (excess air, or stack gas oxygen), percentage of blowdown, feedwater flow rate, etc. At first glance, I'm not sure how you came up with < 29% heat recovery. I "guessed" at some reasonable values for an "typical" 50,000 PPH boiler (100 GPM feedwater flow, #2 F.O. giving 73,000 PPH dry flue gas at 0.24 BTU/lb-F, etc.) and figure the economizer is recovering about 80% (but hey, I've been wrong before!). Anyway, if you think the unit is actually performing poorly, there may be a reason (by design, such as to prevent too low of a gas-side outlet temperature), or it could simply have been undersized to begin with. Maybe it's just very badly fouled, even though your incoming feedwater temp is right up there where it should be. If firing heavy fuel oil, could soot blowing be necessary? Maybe some tubes are plugged as a result of previous corrosion failures.