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Recent Questions
Date  Replies
18/04/2018 Q: What is the typical distribution of catalyst carbon content (coke in wt%) in 4 reactors of CCR (continuous catalyst reformer unit)?  
11/04/2018 Q: Which companies have particular and extensive expertise in executing turnaround of stacked type FCC Orthoflow Units?  
08/04/2018 Q: I have difficulty in drawing product from my side stripper of the atmospheric distillation tower. Whenever I raise the Stripping steam rate, this problem will occur. My initial suspect is due to the hydraulic limitation when the stripping steam is above a certain value. The technical reasoning would be when there is high vapor rate rising up the stripper tower, the vapor load creates high pressure drop across the stripping trays. Liquid flowing from the top will ultimate be restricted from flowing down the stripper tower and creates hydraulic limitation. Do you all agree on this observation? (2)
07/04/2018 Q: High AT in transfer line beetween heater and drum.
After a maintenance shut down of the unit where we have some modifications in this pipe, the AT between heater and drum has increased from 18ºC until 27ºC (average values). We process heavy crudes with a 25%w concarbon and 20% C7 asphaltene.
For this crude, which is the minimum inlet drum T in order to avoid problems with coke formation? (Our current minimal T is around 468ºC)
Which is the maximum coil outlet T to avoid aceletated fouling in the heater? (now we would need to increase up to 500ºC)
We use fierglass insulation in this pipe. Have you tested any better insulation (e.g. aerogel)?
We are thinking to try an electric heat tracing, do you have any reference of this option being used in delayed cokers? Would it cause fouling in the pipe?
(2)
25/03/2018 Q: In our FCC, we process two feeds namely, Coker Gasoline and Mixed feed (Mixture of Residual crude Oil & Coker Fuel Oil). In one of our unit shutdowns, we found very hard coke formed in the Riser at the area of feed nozzles. We did not observe this type of phenomenon in past. What would be the probable causes for formation coke in the Riser? (4)
Recently Answered Questions
Date  Replies
25/02/2018 Q: In our FCC unit, We have two temperature indications in the stripper bed. During start-up of the unit, we observe the two temp. indications show almost same temperature, but during normal operation of the unit, the temp. difference of nearly 100 deg. C between the two temp. indications is being observed. What would be the reason? (1)
26/01/2018 Q: In our refinery, C5/C6 isomerization process uses zeolite based catalyst and reaction loop pressure is maintained at 18 kg/cm2g. The ISOM unit uses H2 makeup from CRU and there is continuous purging of recycle gas from ISOM separator.
the design basis is 1635 kg/hr of purge gas (contains 187 kg/hr of H2) with 63 vol% H2 purity.
No HCL. 5-12 ppm of H2S.
Please advise how economical will it be to recover the H2 from purge gas using membrane separation process?
is there any refinery currently using membrane separation process for recovering H2 from purge gases at 18 kg/cm2g?
(4)
16/03/2018 Q: For a reboiler furnace in NHDT, is better:
to have reboiling liquid 34 m3/hr and furnace COT at 208 C or to have reboiling liquid flow at 40 m3/hr and furnace COT at 203 C?
Note: Reboiler furnace is the limitation for maintaining max throughput.
(7)
08/04/2018 Q: I have difficulty in drawing product from my side stripper of the atmospheric distillation tower. Whenever I raise the Stripping steam rate, this problem will occur. My initial suspect is due to the hydraulic limitation when the stripping steam is above a certain value. The technical reasoning would be when there is high vapor rate rising up the stripper tower, the vapor load creates high pressure drop across the stripping trays. Liquid flowing from the top will ultimate be restricted from flowing down the stripper tower and creates hydraulic limitation. Do you all agree on this observation? (2)
07/04/2018 Q: High AT in transfer line beetween heater and drum.
After a maintenance shut down of the unit where we have some modifications in this pipe, the AT between heater and drum has increased from 18ºC until 27ºC (average values). We process heavy crudes with a 25%w concarbon and 20% C7 asphaltene.
For this crude, which is the minimum inlet drum T in order to avoid problems with coke formation? (Our current minimal T is around 468ºC)
Which is the maximum coil outlet T to avoid aceletated fouling in the heater? (now we would need to increase up to 500ºC)
We use fierglass insulation in this pipe. Have you tested any better insulation (e.g. aerogel)?
We are thinking to try an electric heat tracing, do you have any reference of this option being used in delayed cokers? Would it cause fouling in the pipe?
(2)
Post