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Friday, July 8, 2011

Fired Heaters

Norm. I have attended your seminar many years ago. My question is why do my operators say that they don’t have enough air, yet the air registers at the bottom of the heater are halfway closed. The stack damper is always left open. We could run more crude if we had more air to the heater. Hope you remember me.

--Robert, Indiana


Robert. The problem is not lack of air, but lack of draft. If you open the air registers further, the delta P of the flue gas thru the convective section tube banks will increase and you will develop a positive pressure below the lowest rows of convective tubes. This is dangerous. Hot flue gas with SO2 can blow-out of the upper part of the firebox. Your operators are right to restrict air flow thru the air registers. Is your stack damper truly wide open? Have you tried cleaning the outside of your convective tubes? Have you used your steam soot-blowers regularly? Make sure all tramp air leaks in the convective section have been sealed. Unfortunately, I don’t remember you at all.

--Norm

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