| American Fuel & Petrochemical Manufacturers

Question 7: Comment on your experience with the value generation potential of each of the refinery gasoline processing units - reforming, naphtha hydrotreating, isomerization, alkylation, and FCC-gasoline post-treating. What interplay exists between the units that can be leveraged?

The naphtha catalytic reforming unit can be partially unloaded, by subtracting from its traditional feedstock the higher-boiling C6 hydrocarbons, including naphthenes, benzene and hexane.

Question 6: What are the best practices for mitigating and monitoring Corrosion Under Insulation (CUI) in cold services such as Alky/Isom units?

What are the best practices for mitigating and monitoring Corrosion Under Insulation (CUI) in cold services such as Alky/Isom units?

Question 5: What are your experiences with alternatives to gauge glasses in alkylation units? Are there any specific services where you prefer glass gauges?

Although gauge glasses can and have been used successfully in HF service, it is essential that proper design and very special operating procedures be followed in order to prevent serious incidents. In the past, gauge glasses were sometimes the only option to provide a reliable secondary indication of liquid levels in the HF Alky units in order to verify the sometimes-unreliable primary level instruments.

Question 4: What are the recent safety improvements in the procedures or equipment for sampling sulfuric acid?

What are the recent safety improvements in the procedures or equipment for sampling sulfuric acid?

Question 3: What considerations do you make in determining the need for a safety instrumented system (SIS) in an Isomerization unit? What safety integrity level (SIL) do you use for temperature excursions, liquids fed to the regeneration superheater, or other significant safety events? What typical unit design features do you implement to mitigate these safety events?

For chlorided-alumina catalyst systems (Penex™ and Butamer™ units), the top hazard events for which interlock systems are provided are: Reactor temperature excursion Excessive Temperature in Regenerant (Electric) Superheater.

Question 2: Have seal-less pumps (magnetic drive or canned pumps) been used successfully in HF and sulfuric acid alkylation units? What services are considered for this equipment?

Have seal-less pumps (magnetic drive or canned pumps) been used successfully in HF and sulfuric acid alkylation units? What services are considered for this equipment?

Question 1: What independent protection layers (IPLs) are you using in cyclic reformers during regeneration to prevent hydrocarbon and oxygen mixing through isolation valves? What IPLs are you employing to prevent improper valve switching?

Protection of over-pressuring of upstream equipment is complicated. UOP takes multiple approaches to reduce this risk. Use of two check valves with dissimilar design in series reduces the reverse flow rates.

Question 91: What are your top three causes of unit slowdowns, and what is the loss in onstream factor for each? Please provide the same information for your top three causes of unit shutdowns.

FCC/RFCC units are the one of the major secondary units in almost all of IOCL’s refineries. Irrespective of demand positions, these units are always required to operate at high capacities. All of our refineries had been participating in the benchmarking surveys conducted by Solomon Associates, and the results comparing IOCL FCC units with rest of the world (2014 study) are indicated below.

Question 90: We are planning to purchase a new flue gas steam generator. What is your preferred configuration? What are the critical operating parameters you employ to ensure reliable operation? What is your sparing philosophy?

The configuration of the flue gas steam generator will be predominantly governed by FCC design. For a partial-combustion unit, it will be a CO boiler or a CO incinerator cum FGC (flue gas cooler) combination. For complete combustion, it will be a FGC or waste heat boiler alone. By CO boiler, typically we mean a boiler where the steam generating tubes are exposed to direct flame.

Question 89: For an equipment revamp/replacement, what are the factors you consider when choosing between hot-wall and cold-wall refractory design, including advantages and disadvantages of each?

Shell has experience with both cold-wall and hot-wall refractory designs for reactors and stripper vessels, but regenerator vessels are always cold-wall refractory designs. Depending on the reactor and stripper vessel, refractory type and standpipes, liftpots, and external portions of the riser can be either cold-wall or hot-wall designs.