Why are the furnace tubes of the diesel hydrogenation feed heater of different colors?
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There are 3 rows of furnace tubes in total; the left half of one of these rows is dark black, while the right half contains several tubes with whitish spots. The colors of the remaining two rows of furnace tubes are more uniform, being bright gray. Is there something wrong with this? It feels abnormal for it to be black; it’s too abrupt
It’s likely that the furnace tubes have coked, causing a deviation in the flow of heat through them. This can be determined by checking the surface temperature of each furnace tube, or the temperature at its inlet and outlet, or the pressure difference between these points
There was a coking incident once before, and after cleaning the furnace to remove the coke, special attention was paid to this issue. The pressure drop in the heating furnace remained around 0.35. The surface temperature of the furnace tubes was measured every two hours or so, using thermometers; however, these measurements might not be accurate. Nonetheless, the values obtained from the 8 measurement points were not very different from each other
Optimize the furnace flame. Also, consider the possibility of coking in the pipelines or uneven flow of materials
If it’s a flow deviation issue, is the flow higher in the black furnace tubes or in the gray furnace tubes?
Are there any photos? Under these circumstances, it is likely that the furnace tube has coked up, causing the deviation. The normal color of furnace tubes is fairly transparent; they do not turn black or dark