Crude_Eng
Mechanical
- Apr 24, 2024
- 3
The scenario I'd like assistance on is as follows: There is a Waste Heat Boiler attached to a Steam Methane Reformer and uses the Flue gas from the SMR to generate steam required for the reforming process. The area of concern in the WHB section is the Steam Generator section which consists of 50 tubes which are finned. These 50 tubes are arranged into 5 passes in the steam generator section. Thirty tubes at the top of the steam generator have tube inserts (scrolls) installed while the remaining 20 below have nothing installed in them. Tubes are 4.5" OD and 9.5m in length.
There has been a repeated failure on the same tube, located in the line closest to the equipment wall. The failure has occurred every 4-5 months and occurs between the 12 o' clock and 3 o' clock position at approximately the midpoint along the length of the tube. The failure morphology is likened to that of a pinhole. When examining the flow through the pass, it is the first tube that does not contain a tube insert in that pass. However, none of the other tubes in the same location in other passes have experienced this frequent of a failure.
The remedial activities attempted in the past were as follows:
1) The tube was replaced with a like for like replacement upon the first and second of the frequent failures.
2) The entire pass was replaced with like for like material upon the third failure. Boiler Feedwater Flow rates between passes were also measured on site during commissioning to establish any discrepancies in the passes with none noted. The same tube has subsequently failed in a similar time frame with the same failure.
Are there any recommendations from experts regarding what could potentially be changed to alleviate this problem?
There has been a repeated failure on the same tube, located in the line closest to the equipment wall. The failure has occurred every 4-5 months and occurs between the 12 o' clock and 3 o' clock position at approximately the midpoint along the length of the tube. The failure morphology is likened to that of a pinhole. When examining the flow through the pass, it is the first tube that does not contain a tube insert in that pass. However, none of the other tubes in the same location in other passes have experienced this frequent of a failure.
The remedial activities attempted in the past were as follows:
1) The tube was replaced with a like for like replacement upon the first and second of the frequent failures.
2) The entire pass was replaced with like for like material upon the third failure. Boiler Feedwater Flow rates between passes were also measured on site during commissioning to establish any discrepancies in the passes with none noted. The same tube has subsequently failed in a similar time frame with the same failure.
Are there any recommendations from experts regarding what could potentially be changed to alleviate this problem?