Q & A > Question Details
We have a semi regen platformer unit. After regenerating the catalyst, unit was started up and observed that reactor 1 delta temperature (we have 3 reactors ) is low and almost same as reactor 2 delta temperature. And the Platformate RON is also low at about 92 whereas the expected RON at start of run is about 94. This is the first time we experience this kind of a behaviour. There was no sulfur ingress or any other change in the feed stock (Heavy naphtha). The issue seems to be in reactor 1 and other two reactor delta temperatures are similar to the previous cycles. Can anyone help me on possible causes for this issue?

Additional info:
Appreciate the valuable comments. To add some more information, We do process only the virgin naphtha. Sulfur and nitrogen are less than 0.5 ppm as required. Feed is from Murban crude which does not have high metal content.However, it appears that the reactor 1 delta temp is in decreasing trend and reactor 2 delta temp has increased slightly. H2 purity also low and gases and lpg are on higher side. PONA test indicated that paraffin conversion is low compared to previous cycle SOR conditions. Catalyst samples were checked after oxidation and reduction steps. Appearance of reactor 1 samples were better compared to reactor 3 except the reddish rust coating in reactor 1 was high. But, this coating in reactor 1 was same as in previous cycles samples as well. Also, we are maintain little higher cl level as this is the 9th cycle of the catalyst and expect lower cl retention in catalyst.

New info:
By today, the reactor 1 delta temp has further decreased and reactor 2 also is seems to be in decreasing trend. A new information is that there was a upset in recycle gas compressor during regeneration (oxidation step). Seal oil loss increase due to seal damage and both the seals were replaced along with damaged bearings. But, labyrinths haven't changed. And we observed some seal oil in compressor discharge line ( some drops of seal oil leaking at the compressor discharge isolation valve flange). Therefore, we checked at casing drain line and another low point in discharge line. First day (two days ago), we found some significant amount of oil collected. After draining them, the next two days found only small collection. Anyhow, now we are doubtful about a lub oil contamination. In addition, can there be a possibility of channeling the first reactor? Because if so we have to dump the catalyst during regeneration. Another thing is that during regeneration, there was a strong detection of hcl in reactor 1 outlet ( more than 500 ppm).
 
Answers
30/11/2016 A: Patrick Bullen, UOP, patrick.bullen@uop.com
If the lube oil used is a synthetic type with low metals, then it would likely just generate coke on the catalyst. However, many conventional oils have metal levels that could cause catalyst deactivation. As others have stated, there are a number of contaminants that could be a source of lead reactor deactivation. An improper chloride/water balance could also cause catalyst activity to fall. High chloride levels are an indicator of chloride stripping which is typically caused by high water concentrations.
If you would like more detailed help, you can go the following or contact your local UOP representative:
Login to the UOP Customer Portal www.AccessUOP.com to explore our Knowledge Base, Frequently Asked Questions, Tools and more. Not a portal member? Click on Registration to create your user credentials.
29/11/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
you may estimate seal oil loss. Seal oil that reaches furnace will generate water leaching more chlorine. modern regn methods yield high hcl in RG. If seal oil has caused poor regn, you will regain activity after fresh regn. unless permanent poisoning occurred. I observed successful regn in spite of seal oil loss.
29/11/2016 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
I assume you do not have a standby load of catalyst. Some refiners keep a standby reconditioned load. With your issues and 9 regenerations, I would shut down and replace the catalyst and send out the current load for reconditioning. It is expensive to own extra noble metals but would set you up for future unexpected change-outs.
29/11/2016 A: Satyalal Chakravorty, Sr Consultant, satya1354@yahoo.co.in
Then it is the case of Sulphate (SO4) formation on the catalyst during the regeneration undertaken. One has to undertake sulphate stripping procedure, as recommended by the licenser. During such operation, monitoring of the parameters & other actions are essential.
28/11/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
Drop in RON of 2 units corresponds to an increase in RIT by about 5 degree C suggesting catalyst deactivation. The deactivation may be due to various reasons. Some of which are:
1- Improper regeneration. The reactor 1 coke burn and oxychlorination data to be looked into seriously. Whether R1 has experienced sulfur upset prior to shut down of regeneration. It could partially lead to sulfatation of alumia suport.
2- Post regeneration sulfiding of catalyst.
3- As per kinetics the drop in 1st reactor could shift to 2nd reactor and is not observed by you. it could reflect issue in 2nd reactor too
4- Higher H2/HC mole ratio could also reflect in reduction in delta T to some extent because of high heat capacity of additional hydrogen
5- Low chloride in catalyst in R1 also leads to catalyst deactivation effecting delta T and reactions.
6- keep a watch on moisture content in charge stock and RG
7- Probably check for permanent poisoning of R1 catalyst
I hope by now situation would have improved
26/11/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
The drop in temperature of reactor 1 is dependent
On number of factors some are as follows:
1- Napthene content of charge or say PONA
2- State of cat. activity. Whether it is poisoned by sulfur or any other poison. The reason can be investigated with suitable analysis.
3- Whether poisoning of catalyst has occurred due to improper regeneration like sulfation of support or improper oxychlorination and poor water - chlorine balance
4- The change in delta t of 1st reactor has impact on 2nd reactor.
5- Higher H2/ HC rstio also has some impact on delta t due heat capacities.
6- Thruput or charae rate.
26/11/2016 A: Satyalal Chakravorty, Sr Consultant, satya1354@yahoo.co.in
Please trace the regeneration steps undertaken including the oxichlorination steps (which rejuvenate the catalyst with chlorides) carried out. Otherwise the reactor 1 delta temperature should have been highest.
26/11/2016 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Calibrate the No. RIT. If the temperature is actually low, you could have the conditions described. I agree with comparing the yield structure and moisture. If the light ends are not high, try increasing chloride.
25/11/2016 A: JUAN SEGURA, PDVSA, SEGURAJH@PDVSA.COM
The main causes of a reduced temperature drop (DT) is due to contaminants in the feed. As you mentioned that there were no changes in the feedstock, it is important to verify if there is any chance that feedstock can be contaminated some how (eg. possible entrainment from other tanks, external naphtha from ships, etc). Sulphur and/or nitrogen can cause a reduced DT. In some cases when you lose DT in 1st reactor then DT in 2nd reactor can increase due to naphthenes dehydrogenation is verified then in 2nd reactor. But in your case you mention that both DT in 1st and 2nd reactors are almost the same, so maybe you will experiment later an increased DT in 2nd reactor for a period of time before contamination reaches 2nd reactor. It is important to verify more information, such as H2S content in recycle gas, LPG production (eg, for sulphur contamination LPG yield increase), recycle gas purity, and H2 yield, C1 and C2 production and reformate yield. additionally, do you process virgin naphtha only or you have a fraction of cracked naphtha in your feed? because you need to consider metals, nitrogen content. The last thing that I can mention is the metal dispersion during regeneration was not correct and the activity of the catalyst (metallic function is affected). Check also PIANO to verified nathphenes.
25/11/2016 A: NS Murthy, Suez, murthy.ns.ext@suez.com
During regeneration, chloride in catalyst may get leached. Addition of per chloro ethylene would help to raise the activity. Further, you did not mention on pr drop. Is there any increase post regeneration operation? Also, look at moisture level in recycle gas. If high check for water ingress thru feed. I hope PONA of feed composition is same as previous,