Coke drum vibration

[jooyeonpark]

Hi, I’m currently working in refinery company
I have few questions about coke drum vibration issues

[ Current situation ]
-HDO witness noticeable vibration during the operation.
-Witness the stronger vibration while one drum at 60 to 70 % feed rate and other decoking
-Vibration consultant has measured the vibration and provided us with the analysis of
vibration data using “DIN 4150 Vibration Criteria of 10 mm/sec”

[ Operational significant ]
-HDO has installed the bottom auto unheading valve(delta valve) in May 2014. With this modification,
the feed entrance has changed to side from the center. Moreover, flow rate has been
increased by 10% after the installation
-Coking cyle reduced from 16 hrs to 13-1/2 hours(36,000BD) after bottom auto unheading addition
-HDO uses heavy crude after year 2014

[ Questions ]
1)Are there any other companies which have the similar experience like us after installing the bottom delta valves?
-Especially, when feed entrance changed to side from center as HDO’s case

2)How did the particular company which had the same issue solve this vibration problem?

[evan]

Hello –

I have participated in some vibration harmonic analysis of some units with severe vibration issues. One example had 1 hz period with a magnitude of deflection that exceeded 20 cm in some piping. The issues come and go but seem to be related to a number of issues…..

+ feed composition and vaporization rate in the transfer line
+ heater COT
+ Angle of inlet nozzle
+ Random channeling in the coke bed

Are you able to reproduce the problem with every drum or does it only occur on some drums?
Do you have skin TI around the coke drum to monitor for differential heating?

I’m not sure I understand what you mean about feed rate effects on 1 drum during decoking. I believe you only have a 2 drum unit at HDO so this should always be the case.

Have you considered the Deltavalve center feed device. If the problems are severe and consistent, this would be a good solution for your plant.

[evan]

Hello –

I have participated in some vibration harmonic analysis of some units with severe vibration issues. One example had 1 hz period with a magnitude of deflection that exceeded 20 cm in some piping. The issues come and go but seem to be related to a number of issues…..

+ feed composition and vaporization rate in the transfer line
+ heater COT
+ Angle of inlet nozzle
+ Random channeling in the coke bed

Are you able to reproduce the problem with every drum or does it only occur on some drums?
Do you have skin TI around the coke drum to monitor for differential heating?

I’m not sure I understand what you mean about feed rate effects on 1 drum during decoking. I believe you only have a 2 drum unit at HDO so this should always be the case.

Have you considered the Deltavalve center feed device. If the problems are severe and consistent, this would be a good solution for your plant.

[Author]

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