Optimized coke cutting method for decoking substantially free-flowing coke in delayed cokers

• US 20090057126A1
• Filed: 08/27/2007
• Published: 03/05/2009
• Est. Priority Date: 08/27/2007
• Status: Active Grant

• Current Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Inventors: Phillips, Glen E., Mart, Charles John
• Granted Patent: US 7,815,775 B2
• Time in Patent Office: Days
• US Class Current: 201/1
• CPC Class Codes: C10B 33/00 Discharging devices; Coke guides
• CPC Class Codes: C10B 41/04 by electrical means
• CPC Class Codes: C10B 43/08 with liquids

Abstract

A method for coke removal in delayed coker drums is provided. The method comprises the steps of draining from the drum of substantially free-flowing coke, performing a vibration signature analysis on the drum to identify whether and where any coke remains attached to the interior wall of the drum after the draining step, and cutting the coke from the areas identified by the signature analysis step.

Claims

1. A method for coke removal in delayed coker drums comprising the steps of:

(i) draining a drum containing substantially free-flowing coke;

(ii) performing a vibration signature analysis on the coke drum to identify any areas on the drum where coke remains attached to the wall of the drum after the draining step;

(iii) cutting the coke from the areas on the drum identified by the vibration signature analysis.

2. The method of claim 1 where the step of performing the vibration signature analysis is comprised of the steps of:

(i) ringing the drum to induce vibration of the drum;

(ii) measuring the vibration to obtain a ring signature;

(iii) comparing the ring signature with a previously determined clean condition signature of the drum;

(iv) determining if the ring signature varies within predefined limits of the clean condition signature;

(v) obtaining a drum signature profile if the determination in step (iii) reveals results outside the predefined limits;

(vi) analyzing the drum signature profile to identify areas on the drum where coke remains attached to the wall of the drum.

3. The method of claim 2 where the drum signature profile is obtained by:

passing a drill stem in cutting mode down the height of the drum; and

taking a series of measurements of the vibrations produced by the impact of the water from the drill stem corresponding to different heights on the drum.

4. The method of claim 3 where adjacent measurements in the series are compared to determine the presence of a shift in the signatures.

5. The method of claim 2 wherein the substantially free flowing coke is a slurry.

6. The method of claim 5 wherein the slurry is comprised of shot coke and water.

7. The method of claim 2 wherein the ring signature is measured in step (ii) using an accelerometer.

8. The method of claim 2 wherein the ring signatures are compared in step (iii) using pattern recognition software.

9. A method for determining whether a coke drum is clean by performing a vibration signature analysis on the coke drum to identify any areas on the drum where coke remains attached to the wall of the drum.

10. The method of claim 9 where the vibration signature analysis comprises the following steps:

(i) ringing the drum to induce vibration on the drum;

(ii) measuring the vibration to obtain a ring signature of the drum; and

,

(iii) comparing the ring signature with a previously determined clean condition signature of the drum.

11. The method of claim 10 wherein the signatures are compared in step (iii) using pattern recognition software.

12. The method of claim 11 wherein the signature is measured in step (ii) using an accelerometer.

13. A method for preparing a delayed coker drum for a new batch of feed after being drained of substantially free-flowing coke comprising the steps of:

(i) performing a vibration signature analysis on the coke drum to identify any areas on the drum where coke remains attached to the wall of the drum after the draining step;

(ii) cutting the coke from the areas on the drum identified by the vibration signature analysis.

14. The method of claim 13 where the step of performing the vibration signature analysis is comprised of the substeps of:

(i) obtaining a drum signature profile;

(ii) analyzing the drum signature profile to identify areas on the drum where coke remains attached to the wall of the drum.

15. The method of claim 14 where the drum signature profile is obtained by the substeps of:

(i) passing a drill stem in cutting mode down the height of the drum; and

(ii) taking a series of measurements of the vibrations produced by the drill stem corresponding to different heights on the drum.

16. The method of claim 15 wherein the vibrations are measured by an accelerometer positioned on the outer side of the drum.

17. The method of claim 15 where adjacent measurements in the series are compared to determine the presence of a shift in the signatures.

18. The method of claim 17 where cutting is directed toward the position or positions where there is a presence of a shift.

19. The method of claim 17 wherein the signatures are compared to determine the presence of a shift using pattern recognition software.

20. The method of claim 14 wherein the substantially free-flowing coke is a slurry.