Q & A > Alkylation
Date  Replies
30/08/2020 Q: Is the UOP qualified vendor list for different process units such as NHT, DHT, ISOM, FB Platformer, CCR, FCC and Uniflex publicly available?

10/06/2020 Q: i'm working in a LAB plant. For dehydrogenation of paraffins there are 2 standby reactors. After deactivation of the catalyst (about 45 days) we changed to another one. Now we want to use both reactors at the same time in parallel. We increased the paraffin flow rate from 50 t/hr to 60 t/h. The hydrogen flow rate also increased from 10 t/h to 11.5 t/h according to our equipments capacity. I think it'll raise our conversion and increase the catalyst lifetime. Is this possible?

01/10/2019 Q: Hello,

In our refinery we have an alkylation unit with HF and in recent dates we have had many problems with the acid vaporizer of the HF regeneration column (acid leaks from the tubes). The tube bundle is monel 400 and the heating medium is tempered medium pressure steam. Do any of you have similar experiences and could you help us find the failure mechanism?

Thank you.
18/12/2018 Q: I saw an answer in Q&A, that portable electric desalters will screen the demulsifiers. I would like to screen some of my demulsifiers using portable electric desalter (PED). Can anyone suggest the suppliers of PED? it would be a great help. (3)
31/08/2018 Q: At present we face sudden increase in bromine index for benzen product in our aromatic plant. This cause our benzene product to goes to off spec as the BI exceeded the spec limit. We did several actions in order to improve the Bi level, hot clay treater for BT cut , one was isolated for replacement and only one remaining now in service and operated at higher temperatures, so is there any one has such experience. Please advise
Also the Bz losses in raffinate product from extractive column was increased to allow more lifting of heavy olefin, but still the observed effect is very minor ,so please share with us your experience if any for such case.
06/12/2017 Q: I wanted to understand the constituents that cause the coloring in say natural gasoline. I'm working on an NGL fractionation unit & the Debutanizer bottoms is routed to a Decolorizer column. Now, I'm not sure what is removed to actually meet the D-156 saybolt color 20 specification. its gas condensate...C5-C20, mercaptans inc heavy mercaptans i.e c5,c6 mercaptab, BTEX. No MEROX unit on the feed stream..so no DSO. Also no N2/ nitrogenous compounds.
I would be very grateful if somebody could share the HC compounds contributing to color other than the obvious DSO/ N2 compounds.
23/10/2017 Q: In our plant, we have 7 heaters for Distillation unit, NHT and CRU unit. Fuel Gas that is generating from CRU Unit (80% H2) is being used for all those heaters. But, gum or glue is observed at the pressure regulating system which is situated on fuel gas line which mean it is depositing at the reduced area due to restricted flow path. My question is that if the olefin/unsaturated compound present in the desulfurized naphtha ( CRU Feed), is it getting Oxygen from Oxygenated compound like MTBE, TAME or Methanol and so on to form gum or is it getting O2 from the existing system? If this is not the case then what could be the reason of forming gum in the fuel gas? (3)
16/05/2017 Q: During the drying of fusel oil, what are the correct proportions and quantities of fusel oil and sodium chloride solution used for mixing? What amount of the filtered solution is distilled?  
08/05/2017 Q: Fusel oil removed during distillation. It contains various higher alcohols. What is the standard procedure for separating isoamyl alcohol? (1)
21/01/2015 Q: We have a kettle type reboiler with weir plate and its liquid outlet is going regenerator in benfield process of co2 removal in ammonia plant. Is it necessary or required to put vortex breaker in the reboiler liquid outlet? Which design is applicable for designod reboiler? (1)
30/12/2014 Q: This question is related to kerosene merox unit. After processing kerosene in merox unit, what are the main reasons for poor saybolt color of kerosene product? If kerosene feed to the merox unit has saybolt color of +26, kerosene product from merox unit observes saybolt color of <16. Can someone explain the possible compounds which causes color problems to the kerosene product? If we go to Kerosene Hydrotreater, there will not be any issues of color problems and in fact it will be improved because of olefin and aromatic saturation. Please share any literature or chemistry related to the kerosene color problems in merox units. (3)
18/12/2014 Q: I'm doing a work about octane rating, but I haven't find the Research Octane Numbers of cis-1,2-dimethylcyclopentane and trans-1,2-dimethylcyclopentane. Who can tell me? (3)
25/09/2014 Q: Can we process FCC's Clarified oil (CLO) or Decant oil as feed to Hydro cracker? My question is that Unconverted oil from Hydro cracker is usually good feed to FCC, So I would like to know if we process FCC CLO in hydrocracker then how much of it will it to convert to Unconverted oil in Hydrocracker? We will use filters to reduce catalyst content in CLO so that hydro treater won't get affected. (2)
19/07/2013 Q: Can someone please help me with information on any recent advances in the alkylation process in a petroleum refinery and differences in the action of solid acid catalyst and liquid acid catalyst. (3)
22/05/2013 Q: Can propylene be used as a co-feed to H2SO4 Alkylation plant? The plant is designed for C4= with iso-C4 case only. What are the pros and cons of co-feeding? (1)
17/06/2012 Q: Excuse my ignorance; I am neither a chemist, nor an engineer. My question revolves around RVP and RON properties of aklylate and refomrate.
From what I have read (obviously not enough), my logic dictates:
1) Unsaturated hydrocarbon molecules are more volatile than that saturated ones, thus will have higher RVP
2) Lighter hydrocarbon molecules are more volatile than longer chains, thus will have a higher RVP.
Questions that are driving me nuts:
1) How can a naphtha feed (with more saturated content) going into a catalytic reformation can have a higher RVP, than the resulting reformate which has more aromatics (unsaturated, cyclical = more volitile) content?
2) Why does alkylate which has more saturated molecules than reformate have lower RON and higher RVP?
3) Which is the most important contributor to RVP of a gasoline blendstock - the length of the hydrocarbon chain or it being un/saturation with hydrogen atoms? In other words, which has higher RVP - an unsaturated aromatic benzene molecule or a saturated paraffin pentane?
13/05/2012 Q: Basic differences between AFQRJOS Issue 25 v Issue 26 may please be explained. (1)
01/05/2012 Q: Over past 5 months, we have suffered from increased (by 25%, 30 ton/day) sulfuric acid consumption of our alkylation unit.
Now, we doubt increased non-regenerated alkyl sulfate formed by butadiene and / or increased acid soluble oil formed by olefin polymerization.
1. Actually, the butadiene content of C4 olefin feed has widely been ranged from 0.2 to 1.0% according to our lab analysis (thru PONA analysis), and apparently there is no tend that the butadiene content has been increased. Are there any methods to analyze the butadiene content more precisely. It's known that the butadiene makes non-regenerated alkyl sulfate by strong reaction with sulfuric acid and goes to acid phase, which reduces acid concentration. Are there any methods to analyze the alkyl sulfate content in the spent acid?
2. The C4 olefin feed comes from our RFCC unit which uses ZSM-5 as an additive to boost propylene production as other RFCC's. Can ZSM-5 increase the butadiene content in the C4 olefin feed? Actually, we have used ZSM-5 for a long time in the RFCC unit, and recently we changed the brand of ZSM-5 at the end of last year. Can the butadiene content in the C4 olefin feed be much affected by the type and vendor of ZSM-5?
3. Are there any methods to analyze the acid soluble oil content in the spent acid? Can higher iC4/Olefin ratio reduce the acid soluble oil content in the spent acid?
02/03/2012 Q: How to keep the pH in neutralization pit neutra? Alkylation unit uses HF and in the neutralization pit we use KOH. The pH is very erratic ranging from 8-14. (2)
30/10/2011 Q: With regard to application of catalysts in Isomerisation process, I would like to know about the overall comparison between tradition catalyst i.e. Aluminium Chloride and novel catalysts based on platinium element. In point of view of economical criteria which case has been suggested? (3)
01/11/2010 Q: I am interested in knowing more about the options of value addition to C4 stream produced in FCC / CDU.
C4 produced consists of a mixture of N-Butane, Iso-Butane and Butylenes.
Following value addition routes exist:
a) Recover Butylenes and convert them to Propylene using OCT (Olefins conversion technology).
b) Recover Butylenes, Isobutane and convert them to Alkylate in Alkylation.
c) Recover Iso-butane and use as a feed to Alkylation.
I would like to know if there are other routes of value addition available or any synergy with a Petrochemical complex. What are the options for N-Butane for value addition?
09/07/2010 Q: What is odorless kerosene? And how is it processed? (2)
21/05/2010 Q: I am working on CDU as a field operator.
I want to know why NH3 or NH3H2O is injected in overhead line of distillation column?
Why dont we use NAOH for nutralization there? Even NAOH is cheaper then Ammonical water.
11/09/2009 Q: What are the typical benefit one could expect from APC implementation in Alky (sulphuric acid based) unit? Also, has anyone used early event system to forewarn operator on reaction section operation? (1)
12/05/2009 Q: I read that most of the existing alkylation units use HF in their process and the newer ones sulfuric acid. How is the flow of HF measured - and the H2SO4?  
01/05/2008 Q: What are the conditions leading to brine production in a Catalyst cooler?  
03/12/2007 Q: Would you please share experiences of C4/C5 alkylation?
We are adding C5 alkylation to existing C4 alkylation.
It has a SAR (Sulfuric Acid Regeneration) unit.
Do they usually feed C4 and C5 mixture?
1. Is there any existing unit which is fed C4 and C5 separately?
C5 segregation cause any problem? Licensor says we consume less Sulfuric Acid than mixed feed.
2. With segregated C5 feed, spent acid strength will be 87wt%. Are there any critical reliability issues due to lower spent acid strength?
- reactor corrosion
- spent acid disposal and regeneration unit (SAR)
29/11/2007 Q: What is the present global alkylation capacity? And the largest alkylation unit? (5)
16/09/2007 Q: If my gasoline pool is not limited by Rvp, then is it advisable to go for a isomerization unit if I have iso pentane availability. Iso pentane RON is 83.5 and isomerate is 87.5 (2)
11/09/2007 Q: Can anybody share experiences of using high efficiency trays in an isostripper column? (1)
05/09/2007 Q: What is the status of the first commercialization projects using solid alkylation catalysts? (3)
17/08/2007 Q: In our naphtha hydrotreating unit, iron contents in stripper overhead boot are being reported on higher side for the last month. So far we have tried the following:
1. Increased corrosion inhibitor injection from 3 wt ppm (design) to 7 wt ppm.
2. Replaced the corrosion inhibitor
3. Cold condensate injection in reactor effluent increased from 3 to 5.5% of feed.
But iron contents are still high (2~3 ppm).
What could be the possible cause and what is the solution?
22/07/2007 Q: Are there any recent alkylation projects that you can comment on where mass transfer efficiency improvements showed significant reductions in required acid consumption? Also, what recent improvements have resulted in reduced water wash or caustic wash requirements? (5)