We are using born heaters for CRU unit where all heaters inlet lines are covered with ceramic fiber Jacket as air seal purpose but few outlets pipeline from radiation section are not covered. Currently bluish flame is observed coming out from gap/clearance between the outlet pipe and and heater shell casing pipe during night time. What could be the reason for that (from 3rd Heater which has no convection section but has common stack with 1st & 2nd heaters) ?
Another day in the same heater, red hot spot at the inlet of pilot line (pressurized ) was observed and became normal just after the pilot air line had been isolated/closed. But at the pilot inlet found little flame coming out from pilot fuel gas line and disappeared when pilot fuel was isolated. Although pilot should remain close just after the main burner lighted but in our case we keep the pilot in on position all the time. What could be the reason of this red hot spot?
We have VFD operated blower , some time blower noise becomes very high and try to reduce the noise by adjusting the VFD speed . So, what could be the reason for high sound ?