Hydroprocessing Reactor Internals

Abstract

As discussed in other chapters, catalytic hydrotreating upgrades petroleum fractions by saturating olefins and aromatics with hydrogen, and by converting contaminants such as sulfur, nitrogen and sometimes oxygen into H₂S, NH₃, and H₂O respectively. Hydrotreating also remove trace elements such as Ni, V, Fe, Si, As and Hg. Catalytic hydrocracking converts heavy hydrocarbons into lighter material by breaking carbon-carbon bonds.

The hydroprocessing process is exothermic, and thus produces heat as the process stream and treat gas are reacted in the catalyst bed. Controlling temperature rise is a major concern during design and operation. Flow distribution is also important. Inside reactors during normal operation, fluid flow is the only significant way to remove process heat. Uneven fluid flow can impair performance. It can lead to hot spot formation, which can jeopardize process safety and catalyst life.

While proper catalyst loading and grading is very important, reactor design, specifically the internals, is the key to controlling both the exotherm and fluid flow.

This chapter provides an overview of essential components of reactor internals, with emphasis on the relative performance of different designs.