Chemical cleaning instead of steam purge during refinery S/D

[1906]

Re the shut-down of refinery utilizing chemical cleaning instead of steam purge to avoid H.C emission, if you guys have good experiences and materials please let me know.

We still wonder whether this practice really good in view of cleaning performance. Your comment will be very helpful.

 

[Jason5000]

I avoid chemical cleaning wherever possible. Planning it is a hassle, and execution has potential to turn into a real mess. The condensate and/or effluent needs to be carefully controlled and likely captured to avoid upset to the waste water plant or sour water handling systems.

That being said, chemical cleaning does have its place. It has been my experience that heavy oil circuits like reduced crude, vacuum units, cokers, FCC, etc. can benefit from chemical cleaning; just don't expect them to be totally spotless even after a good chemical cleaning. Also, anywhere you have a packed column that you'll be working with chemical cleaning can be beneficial. If experience or type of unit suggests high likelihood of pyrophorics being present some neutralization may be in order.

Something as simple as injecting a little potassium permanganate can go a long way towards oxidizing pyrophoric material. Bleach solutions used to be used sometimes, but they've fallen by the wayside in favor of permanganate due to a few safety reasons. Bleach in the presence of ammonia can produce chloramine which is toxic and can be explosive under the right conditions. Also, when bleach and alkanolamines get together they make a nitrogen mustard that is not only an inhalation hazard, but also a a blistering agent. The chlorides in bleach can go a long way towards cracking austenitic stainless steels too. This is why its really important to know and understand what's in your pipes and how it might interact with anything different you add to it during a shut down.

In terms of commercial solutions, PSC's LifeGuard and United's Zyme-Flow come to mind for chemical cleaning purposes, and these companies could help assess potential hazards too.

 

[Jason5000]

There is also no better time that chemical cleaning to contaminate your utilities and cause untold headaches. Never count on heat exchanger bundles not leaking. Getting cleaning solutions into your cooling water or condensate systems can really ruin your day. I'd recommend blinding utilities prior to cleaning to be assured of positive isolation.

If cleaning chemicals will be coming in contact with pump seals then compatibility should be evaluated as well. Particularly if the pump is in autoignition or highly hazardous service. If you're pumping methyl-ethyl-death and experience a seal failure upon startup because a cleaning solution chewed it up...well, have your resume updated.

There are a whole lot of things that I've seen go wrong during and after chemical cleaning, and other members on here can probably chime in with plenty of their own horror stories that have never even occurred to me as possibilities. Long story short, due to the hazards of putting foreign chemicals in a process unit and managing transient conditions I always default to a simple steam out unless the circumstances really do warrant additional precautions and the benefits of doing something beyond a traditional steam out truly outweigh the risks of chemical cleaning.