Process Technologies

For the post-treatment of FCC gasoline, fixed-bed HDT is by far the most trusted solution because of its low capex, its ease of operation, and its flexibility.

Hydrogen consumption in a hydrotreater comes from hydrotreatment reactions but also from losses within the process.

In order to ensure that there are no solids in the amine system, Axens recommends an amine filtration package which filters a slipstream of the lean amine to remove solid particles. The amine filtration package also includes an activated carbon filter for hydrocarbon elimination and a polishing filter to remove any charcoal fines.

Shutdown operations of the sour water stripper unit should maximise the removal of H2S and NH3 from water, especially for long duration shutdowns, to minimise the safety concerns and corrosion issues during maintenance. If the sulphur recovery unit is not available, the sour gas should be routed to flare, then start the shutdown by decreasing the sour water feed to the unit manually and slowly.

Catalytic systems towards better coke and/or dry gas selectivities will certainly help, especially to face contaminant metals which catalyse side reactions. If not limited by catalyst circulation, low delta coke catalysts will increase cat/oil but coke yield should stay constant.

There is certainly an advantage in challenging the catalyst formulation in order to better suit your needs. This could result in a better conversion at same operating conditions or, as suggested, similar conversion at reduced riser outlet temperature (ROT).

With the fall of pump prices, US consumers have responded relatively quickly by increasing gasoline demand, which has led to increased gasoline crack spreads and incentives for refiners to switch from middle distillates to gasoline in the short term. This phenomenon has been especially true in markets affected by unexpected outages.