The biggest contributor to utility cost per barrel in a hydrotreater is probably the unit operating pressure. Higher pressure units require more energy to pump up the charge, hydrogen, amine and wash water.

There are several considerations when deciding if jet fuel and diesel should be co-processed or hydrotreated separately. The most important consideration is if the jet fuel will be blended into the diesel product or if separate products are desired. The decision may depend on if you are looking at constructing new facilities or making the best use of existing equipment.

Regulatory specifications for the gasoline and diesel pool, which are constantly evolving, have been in the forefront of refiners’ challenges in the last 15 plus years. In particular, the gasoline sulfur regulations have been a main driver for the remodeling of many refineries’ configurations.

Maintaining control means that the dog walker – needs to be able to hang on to the dog – even if it starts to walk or run away. This takes adequate reserve strength - and an early detection and response when the dog just begins to become distracted or when we begin to feel the pull on the leash.

10% ethanol in gasoline regulation which lowered the gasoline octane required from the refinery.  At 10% blending ethanol raises the (R+M)/2 octane of regular gasoline about 2 numbers. 

Refiners have been pursuing the use of more atypical feeds to their olefin oligomerization units for various reasons. Units have historically operated on FCC LPG cuts, but an interest to process Coker LPGs or even heavier FCC olefins have begun.

The recycle compressor is water washed at every catalyst regeneration (typically once per year) after the chlorination step. In addition, if there is any extended outage for mechanical work, the compressor will be water washed anytime there is an opportunity to do so as precaution.

As a first step and low investment solution, refiners will perform a visual check on the color of tubes to check for color differences or perform a thermal scan of the tubes. These solutions are not very accurate due to iron scale formation and ceramic coating on the tubes.

With increasing quantities of lower octane naphthas reaching the gasoline pool and potential for higher octane demand in the finished stocks, the octane boost from isomerization units has grown in importance. While the installation of new units is ideal, many refineries have been looking at utilizing idled units or converting existing units to isomerization type operation.

On-the-fly catalyst replacements are becoming more common, but still an economic decision for the refiner based on trade-offs between the continuous replacement approach and the historical changing at turnaround approach. On-the-fly catalyst replacement allows for full catalyst replacement while catalyst circulation is maintained, with both reaction and regeneration sections still in operation to allow for reduced unit downtime.