Case 3 – Increasing hydrogen partial pressure - Case 3a – Diesel hydrotreater increase H2/oil ratio? purify hydrogen? change liquid feed? decrease pressure drop? Case 3b – Naphtha hydrotreater    

Case 4 – Pressure Drop Situation 1 – Poor catalyst loading or poor start-up procedures Situation 2 – Internals, catalyst strength or corrosion impurities coming into the catalyst bed    

Case 4 – Pressure Drop Possible causes for pressure drop Reactor - coking, polymerization, particles (FeS), catalyst loading, maldistribution, metal poisons Exchangers - salts deposition, coking, polymerization, particles deposits

Case 4 – Pressure Drop Reasons for this high pressure drop build-up?? 3/4" inert balls Reasons for this high pressure drop build-up?? Reasons for the higher pressure drop in the second bed?? ACT 065 - 12 mm ACT 075 - 6 mm HMC 841 - 3 mm 1/4" inert balls 3/4" inert balls HR-448 1.2 mm DENSE LOAD 1/4" inert balls 3/4" inert balls

Case 4 – Pressure Drop

Case 4 – Pressure Drop Catalyst grading bed – trickle bed reactors

Case 4 – Pressure Drop Scale baskets – Gas phase bed reactors Scale baskets are needed in order to provide longer resistance to pressure drop build up. The role of the basket is not intended to retain the fines which should be trapped on the top layer of inert balls, but to act as a fuse in case of pressure build up They should remain clean Vapors + fines Vapors free of fines Fines accumulation Inert balls 3/4" Inert balls 3/4" Catalyst bed

Case 4 – Pressure Drop Pressure drop must be corrected for process conditions, as gas and liquid flowrates for example Delta P measured Delta P predicted

Desulphurized product Case 4 – Pressure Drop Feed + H2 After start-up a very high pressure drop Was observed across the reactor Desulphurized product + H2 + H2

Case 5 – Hydrogenation Activity + 2H2S S + 2H2

Case 5 – Hydrogenation Activity Régime thermodynamique (HDA) Régime cinétique Equilibre thermodynamique HDA Soufre effluent (ppm) % HDA HDS T1 T2 Température (°C)

Case 5 – Hydrogenation Activity quench (0 t/h) four lit 1 lit 2 lit 3 R1 R2 Opération normale Diminution de la température dans le dernier lit température

Case 6 – Unit Shut-Down In the race of increasing severity in sulphur specifications - NZSD, optimising the unit shut-down and scheduling it as a non routine event is as important for the overall unit performance as a Formula 1 pit stop can be to wining distribution tray removal (mechanical details) reactor inspection under air atmosphere regenerated catalyst pool catalyst activation method catalyst drying catalyst unloading catalyst loading reactor cool down Dedicated flow-bins - FUTURE

  Case 6 – Unit Shut-Down Cooling loop for hydrotreatment units Air coolers  HP separator Gasoil cooling loop To LP separator stripper Pre-heat exchangers Normal operating circuit Compressor stripper By pass to be opened at 150°C Pre-heat exchangers dryer Air coolers  reactor From HP separator Furnace maxi cold GO to storage LP separator