SRU Run-Down Leg Rodding Procedure

[Noel VicenteMember]

Stephen Bleakley
Process Engineer at Calumet Specialty Lubricants

There must be a safer way! I am currently supporting two 20 LTPD sulfur plants with the traditional below-ground sulfur seal legs. The vertical seals, as well as the horizontal run down legs plug very frequently. The current method for rodding out the seal and run down is via a steam lance. This poses several risks to the operator doing this task. Aside from the obvious safety risks, we all know what combining sulfur and water usually lead to. Until above-ground seals are purchased and installed, any recommendations on how to safely and effectively rod out run down lines and seals? Any recommendations/information would be greatly appreciated!

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Roger Maduell
Project Manager

Stephen, It’s hard to provide advice without knowing exactly how your equipment is heated, but you shouldn’t have problems with clean sulphur freezing in the system piping and seal legs if they are properly designed. You may be able to do a retrofit on the existing piping and seal legs rather than replacing them, either with partial jackets or internal tracing. Proper steam heating is the key.Show less

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Fawaz Al-Qattan
Operations Engineer (Amine Unit/Sulfur Recovery)
KNPC, Kuwait

hydroblasting the rundown lines (after isolation) is more effective than using steam lance or simple rodding. It is also effective with traditional seal legs.

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Noel Vicente, P. Chem., P. Eng.
Sulfur Specialist at Refining Community
Calgary, Alberta, Canada

Hello Stephen, flush test is an excellent tool to detect partial plugging but it can also flush the plug before completely blocking the line. Do you experience completely plug lines?

Temperature can play a big role as well, take note that optimum temperature of liquid sulfur for smooth flow is around 145C.

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Ian Beattie
Engineering Consultant
IMERGE SOLUTIONS LIMITED
Billinge, Merseyside, United Kingdom

Hi Stephen, talk to Clearguard.com they have a branch in Spring Texas, and are very active in the refineries.

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Fawaz Al-Qattan
Operations Engineer (Amine Unit/Sulfur Recovery)
KNPC, Kuwait

I wanna add that prevention is key here. We had a frequent plugging issue earlier due to frequent fuel/acid gas firing at low SRU feed. after investigation, one of the causes was that Control room operators were too afraid of tripping the plant that they were switching to mixed firing too early and too long. All we had to do is reduce a little bit the Air Flow Low-Low trip (it was too high initially) and it avoided the issue all together. Now we’ve been running for few months and plugging has not been a concern for some time.Show less

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Fawaz Al-Qattan
Operations Engineer (Amine Unit/Sulfur Recovery)
KNPC, Kuwait

I am not saying that this might be the exact issue in your plant. It could helpful doing a root cause analysis of the issue to tackle the root causes. After that, using steam lance or whatever method will not be a big concern because, i hope, you will not do it that often.

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Stephen Bleakley
Process Engineer at Calumet Specialty Lubricants

Thank you all for the input. I’ve been working turnaround nights in an unrelated unit and haven’t had a chance to respond or try some of these recommendations. Once I get some time back to focus on this issue, I will be sure to respond with feedback!

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Pete Bisila
Flint Hills Resources
Greater Minneapolis-St. Paul Area

First choice is to avoid having to rod out the lines by eliminating the source of the plug. As alluded to above, process conditions may be causing the fouling. Capture and analysis of the plug may tell you if it is carbon based, iron based, or catalyst/refractory based. If you have to rod the lines, the use of a packing gland is highly recommended along with full splash protection PPE. Sometimes a flush of the legs will clear partial buildup by blocking in the condenser outlet and building a liquid level that can then be released into the seal leg. Redesign of the seal leg piping to reduce the number of turns and blowing catalyst fines out of the beds prior to start up is also a recommended best practice

[Becky PetersonModerator]

To view the original discussion on the Sulfur Recovery Linked In group, please use this link – https://www.linkedin.com/groups/3760704/3760704-6144653771994648576

[rohansingh123Participant]

I am looking after maintenance of SRUs in our refinery. We had similar issues earlier in the SRUs. We were able to identify all the root cause and rectify all of them. Currently we are having no issues with sulfur rundown lines. Following are very important when it comes to avoiding solidification of sulfur:
1. Design and fabrication of sulfur jacketing lines.
2. Slope of all Sulfur rundown lines from condensers.
3. proper monitoring of steam traps.
4. Avoid refractory carry over to sulfur rundown lines.
5. Avoid water stagnation at the bottom of sulfur seal legs
6. proper insulation and proper sealing of insulation joints
7. Monitoring of steam inlet temperature

Apart from these, there were several other minute details which were corrected to avoid sulfur solidification. Rodding during initial start-up period is being done with chain pulley block arrangements which are comparatively much safer for workers.

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