September 30, 2009 at 2:48 pm #2985
I would like to hear from others in the Sulfur, Amine and Sour Water processes. I am especially keen on learning from others who have experienced those very very bad days, where something has gone wrong. I have made my share of mistakes and thankfully I have learned from them. If you’re willing please post your “Tales from the Darkside” it would be much appreciated
September 30, 2009 at 5:45 pm #5985
With my compliments to the USW for deligent reporting, I discovered a list of Lessons Learned on the web. It is documentation such as this that we all learn from. I would suspect all of us would find ourselves somewhere in these incidents…or at least very close.
January 19, 2010 at 3:16 pm #5828
See my post in the waste heat steam generator thread. It’s in the process of being a bad day as we have yet to figure out what we are doing wrong.
The other bad day I had was when the sulfur pit overflowed on start up after a TA because both sulfur pumps were found locked up with corrosion products/sulfurcrete.
Smaller bad days were due to lean amine leaks caused by extreme localized corrosion of the heat affected zone of butt welds in hot lean amine piping. 360 degree corrosion of the HAZ was found, almost like it was machined.
Also have had unplanned shutdowns due to knocking the trays out of one side of the amine regenerator tower. Tracer scan on one side looked liked the tower was fine. Opened up the tower and could look from the top to bottom on the other side of the tower. Lesson- scan both sides of the tower when you have split trays.
Lean/Rich Amine exchanger fouling also caused an unplanned shutdown (in January in Minnesota, naturally). Fouling composition was mostly iron, sulfur, silica, and alumina/aluminum. Still not sure where it all came from.
Life is good. There’s no end of lessons to learn in the yellow cokers!
January 19, 2010 at 4:09 pm #5826
You are right about the “lessons to learn” in SRU’s.
The plant I worked in had a 1.5 mile long molten sulfur transfer line between the SRU and the SFU. Among other things, I learned how to troubleshoot steam supply, condensate recovery and jacketed piping just trying the get the sulfur to flow !
Anybody building a new SRU should really pay attention to these details, to avoid having problems later.
January 19, 2010 at 4:57 pm #5825
New technologies improve reliability on long sulfphur transfer lines. Skin effect heat tracing systems are better option (so you can forget about steam traps and jacketed piping!)
January 20, 2010 at 12:23 am #5823
First I would like to say I have had some bad days out in the SRU, but that would be putting it mildly. They were actually days and nights…all blurred together. I think at one point I was just sitting out at the Sulfur Pits in the middle of the night mumbling to myself as to why I couldn’t get our sulfur vapor recovery unit off the pits to work properly and why we were “burping” the pits. Turns out we had air purges on much of our instrumentation that went back into the process. When the unit was out of service for any amount of time, and the process valves were opened back up…Whoopee…we’ve got sulfur folks
January 20, 2010 at 12:27 am #5822
You’ve got that right Claus Graf. We had Vapor lines running from a Sulfur tank two blocks away from our scrubber. Of course all of it was jacketed and steam trapped to kingdom come. Funny how silly steam traps end up being like the Heater Charge pumps in your coker. They don’t work and everything plugs up.
January 20, 2010 at 12:48 am #5821
That is a bad day…those pit pumps are pretty important…how did you find out you overflowed? Hard wire HI LEVEL alarm at the board?
January 20, 2010 at 9:17 am #5820
Well………we outsmarted ourselves, again. We have a single air bubbler level transmitter in the pit that is setup 0-100% at something less than the actual dimensions of the pit. Neither one of our pit pumps would run (there’s another long story beyond that) so we were in scramble mode to get another pump retrofitted and in service. We were over 100% on the level indicator, but we made some manual measurements of the pit depth, level of sulfur, and assumed height of the pit and ‘calculated’ how long we had before we needed to pull the plug on the feed. Unfortunately, we were off on our calcs by about 12 hours. I happened to notice sulfur oozing up through the roof of the pit around the steam coil piping and notified the operators. It was a rather embarrasing day, to say the least.
January 20, 2010 at 9:22 am #5819
Can you elaborate on the skin effect tracing systems? I’m not sure what you are talking about. How do they work? Websites?
I prefer jacketed piping to steam tracing in sulfur service based on my experience. It’s too easy to lose the insulation on traced systems.
Steam traps are an issue, even when considered ‘critical tracing’. You can inspect them all you want, but they can fail the very next minute. There are several trap monitoring devices being marketed that will continuously monitor trap performance and send a wireless signal back to a receiver that allows real time monitoring. It does require setting up a wireless data network, however.
January 20, 2010 at 9:30 am #5818
Claus, one of our challenges is evaluating the risk of a rundown line failure versus the cost of preventing it or mitigating it. We have a single 4″x6″ jacketed rundown line about 1/2 mile long between our sulfur pits and our storage tanks/rail loading unit. Loss of this line would shut down the refinery. Replacing the line/ adding a redundant line is ~$3,000,000. It’s carbon steel piping with 70# steam tracing on the jacket. Theoretically, there are very few damage mechanisms in these services. Loss of steam appears to be the main probable reason for loss of the line, although contaminants and poor steam quality have also been identified. The problem becomes, how do you evalaute the probability of a failure? What are other people doing for reliability strategies around rundown lines?
January 28, 2010 at 9:41 pm #5800
Hey here’s a link that gives a pretty good description on skin effect tracing
http://www.thermon.com/catalog/us_pdf_files/TEP0041.pdf. The link was mentioned before, I believe.
Unfortunately, not everyone’s budget is going to let them get the cadillac heat tracing. Sometimes we just battle it out with steam and traps.
February 8, 2010 at 3:41 pm #5786
The skin effect tracing looks like some cool stuff, and beats standard electric tracing all hollow. I see is has a rating up to 50W/ft on 5000Volts. How does that compare to steam jacket or controtrace heat inputs? Does anyone out there have this installed on a sulfur run down line? Are there any safety concerns or special marking on the line to identify the tracing? Just curious. Thanks
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