Q & A > Question Details
Our NHT feed is designed for C5-90 cut Straight naphtha with no olefins, We are facing problem of increase in reactor outlet temperature of approx. 5 degc(from 324 to 329 degC) for the last 2-3 days . our feed comes from storage tanks( N2 blanketing) which is directly coming from avu column
what could be the possible reasons for high temperature increment in NHT Reactor exotherm?
Please kindly suggest the causes
08/02/2016 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
You state no olefins. It means bromine number/ bromine index have already been checked. C5 - 90 is a light cut may be meant for C5 - C6 isomerization? I hope you have thermocouple measurement at inlet and outlet only. 5 degree of exotherm may result only due to hydrotreating of unsaturate that could be present. Otherwise light cut would not give that much of rise. Try to measure accurately and correlate with furnace outlet, reactor inlet and outlet temperatures with previous runs.
13/01/2016 A: Yogesh Bhintade, Raffinerie Heide, bhintadeyogesh@gmail.com
Forgot to say if nothing works please make a routine check up of the thermocouples.
13/01/2016 A: Yogesh Bhintade, Raffinerie Heide, bhintadeyogesh@gmail.com
Could you please check the delta T over the reactor. If the feed is coming from CDU units or from N2 Blanketed storage tanks the possibility of olefins in feed can be neglected. Also check if you are processing any import naphtha. Check if you have increased the RIT. Check WABT/ WAIT.
09/01/2016 A: Satyalal Chakravorty, Sr Consultant, satya1354@yahoo.co.in
The likely root cause is the presence of olefins the feed stock, the source may be from slop processing at AVU. This may be checked.
06/01/2016 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
If the feed composition has changed, so will the hydrogen consumption. Have you made that comparison?
05/01/2016 A: NS Murthy, Suez, murthy.ns.ext@suez.com
NHT design is stated to be without olefins. But no info given on actual feed. Check BI or Bromine number to verify the presence of olefins in feed. Also, check other species in feed viz. S, N, TAN and Ar level. Further check the recycle gas flow and purity if hydrogen to validate the temp rise noticed.