Gasification Process by Shell Global Solutions International

Application: The Shell Gasification Process (SGP) converts heavy refinery residual liquid hydrocarbon streams with high-sulfur and metals content into a clean synthesis gas (syngas) and marketable metal oxides. Sulfur (S) is removed by normal gas treating processes and sold as elemental S.

The process converts residual streams with virtually zero value as fuel-blending components into marketable, clean gas and byproducts. This gas can be used to generate power in gas turbines and for making hydrogen (H2) by the well-known shift and pressure swing adsorption (PSA) technology. It is one of the few environmentally acceptable solutions for residual hydrocarbon streams.

Products: Synthesis gas (CO + H2), sulfur and metal oxides.

Description: Liquid hydrocarbon feedstock (from very light such as natural gas to very heavy such as vacuum flashed cracked residue (VFCR) and ashphalt) is fed into a reactor, and gasified with pure O2 and steam. The net reaction is exothermic and produces a gas primarily containing carbon monoxide (CO) and H2. Depending on the final syngas application, operating pressures, ranging from atmospheric up to 65 bar, can easily be accommodated.

SGP uses refractory-lined reactors that are fitted with a gasification burner and syngas effluent cooler, designed to produce high-pressure steam—over 100 bar (about 2.5 tons per ton feedstock). Gases leaving the steam generator are at a temperature approaching the steam temperature; thus, further heat recovery occurs in an economizer.

Soot (unconverted carbon) and ash are removed from the raw gas by a two-stage waterwash. After the final scrubbing, the gas is virtually particulate-free; it is then routed to a selective-acid-gas-removal system. Net water from the scrubber section is routed to the soot ash removal unit (SARU) to filter out soot and ash from the slurry. By controlled oxidation of the filtercake, ash components are recovered as marketable oxides—principally vanadium pentoxide. The (clean) filtrate is returned to the scrubber.

Installation: Over the past 40 years, more than 150 SGP units have been installed that convert residue feedstock into synthesis gas for chemical applications. The Shell Pernis refinery near Rotterdam, The Netherlands, uses the SGP process in a close refinery integration. This highly complex refinery depends on the SGP process for its H2 supply. Recently, ENI refinery in Sannazzaro, Italy, has been successfully started-up. Similar projects are underway in Canada and China.

The Shell middle distillate synthesis plant in Bintulu, Malaysia, uses SGP to convert 100 million scfd of natural gas into synthesis gas that is used for petrochemical applications.

A related process—the Shell Coal Gasification Process (SCGP)—gasifies solids such as coal or petroleum coke. The reactor is different, but main process layout and work-up are similar. The Demkolec Power plant at Buggenum, The Netherlands, produces 250 mega watts based on the SCGP process. In total, over 20 licenses are in different phases of project execution using SCGP.

Licensor: Shell Global Solutions International B.V.