December 9, 2020 at 12:08 pm #31882
We are evaluating the exchange of strutured packing from the main fractionator from stainless steel 316L to 410 which is cheaper. The problem of 410 is that it is easier to sulphide formation with risk during maintenance. What is the frequency of changing packing in the main tower? We change every two campaigns (6 years each). What is recommended?
December 10, 2020 at 8:46 am #31883
I have commissioned and operated in 4 delayed cookers. My experience is 4 to 5 years
December 12, 2020 at 4:32 pm #31885
This somehow came to me. I worked on a FCC that had structured packing. It needed to be changed every T/A for us. Where we dealt with cat / coke fines from reactor, the Coker deals with coke fines only. Unfortunately, coke is the problem when dealing with packing. We could not clean out the coke which then had to kept wet. Easier to just replace. I witnessed 2 fires when packing was first introduced and was “cleaned”. As far as the 316L and 410, you should use a metallurgist to answer that question.
December 28, 2020 at 2:30 pm #31969
I think the rational to change the packing is driven by the tower internal inspection criteria. Once every 10 years is what is recommended in API 510 Pressure Vessel inspection.
There is a discussion about vessel internals, “When vessels are equipped with removable internals, internals may need to be removed, to the extent necessary, to allow inspection of pressure boundary surfaces. The internals need not be removed completely as long as reasonable assurance exists that damage in regions rendered inaccessible by the internals is not occurring to an extent beyond that found in more accessible parts of the vessel.” that would allow the packing to stay in place longer as long as all the conditions are met.
I agree with the other comments concerning the fouling of the packing. Replace the packing and investigate why coke is being formed or entrained into the packing.
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