Dear Sir, I watched your video on UA-cam, and it is very nice. In our gas plant ,we have Vertical Cylindrical natural draft fired gas heater. Tube design temp is 350 C, temp at the inlet of convection zone is 700 C Convection zone consist of 7 rows, first three rows from bottom to top is non-finned tubes. The rest from 4 to 7 are finned tubes. We have repeated failures in the convection zone, most tubes fails are at the fourth and fifth rows. The heater is working for regenerating the molecular sieve of the gas dryers, so it is working cyclic , 5 hours heating and then off 3 hours. At the end of heating the burners shut off and fuel cut off inside tubes at the same time while the temp at the inlet of convection tube is 700. The questions are : - Do you think the temp of the tube metal increase at moment of closing the valve of the gas inside the tubes while flue gases temp inside the heater is 700 C causing the tube failure? Is it a good idea to keep , the gas flowing inside tube after shutting off the burners to protect the tubes from flue gases high temp? - Why we have repeated failure at the first 2 rows at the finned tubes in the convection zone? Is because of the design ? Here is the design of finned tubes: Location First put in service Number of failures Fins Dimensions: Spacing (fins/m) Height (mm) Thickness (mm) MCX 2006 11 197 25.4 1.5 API560 : 197 (MAX) 25.4 (MAX) 1.3 (MIN)
Dear Sir,
I watched your video on UA-cam, and it is very nice.
In our gas plant ,we have Vertical Cylindrical natural draft fired gas heater.
Tube design temp is 350 C, temp at the inlet of convection zone is 700 C
Convection zone consist of 7 rows, first three rows from bottom to top is non-finned tubes. The rest from 4 to 7 are finned tubes.
We have repeated failures in the convection zone, most tubes fails are at the fourth and fifth rows.
The heater is working for regenerating the molecular sieve of the gas dryers, so it is working cyclic , 5 hours heating and then off 3 hours.
At the end of heating the burners shut off and fuel cut off inside tubes at the same time while the temp at the inlet of convection tube is 700.
The questions are :
- Do you think the temp of the tube metal increase at moment of closing the valve of the gas inside the tubes while flue gases temp inside the heater is 700 C causing the tube failure? Is it a good idea to keep , the gas flowing inside tube after shutting off the burners to protect the tubes from flue gases high temp?
- Why we have repeated failure at the first 2 rows at the finned tubes in the convection zone? Is because of the design ?
Here is the design of finned tubes:
Location First put in service Number of failures Fins Dimensions: Spacing (fins/m) Height (mm) Thickness (mm)
MCX 2006 11 197 25.4 1.5
API560 : 197 (MAX) 25.4 (MAX) 1.3 (MIN)
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