Stricter environmental regulations and increased availability of natural gas have resulted in gradually decreasing demand for refinery bottoms streams. Refiners around the world are evaluating options to upgrade low value refinery residuals to higher value products.
This paper compares different refinery residue upgrading schemes with the objective of generating low value feed to a gasification complex for production of high value chemical feedstock. The refinery bottoms upgrading processes evaluated include ROSETM (Residuum Oil Supercritical Extraction) solvent deasphalting, visbreaking, and delayed coking. The extra heavy refinery residual stream from the bottoms upgrading unit is gasified to produce syngas in an environmentally friendly manner. The impact of the feedstock value on gasification economics is discussed.
Syngas from gasification of refinery residuals can be used for the generation of electrical power, steam, and hydrogen as well as feedstock for production of a wide variety of chemicals. Syngas can also be converted to a range of liquid hydrocarbon products via the Fischer-Tropsch technology. The gasification complex is not only a source of valuable chemical feedstock but is also a generator of inexpensive utilities for the refinery as well as the petrochemical complex.
Fuel refineries around the world have changed substantially during the past two decades primarily due to changing crude oil supply, varying product patterns, and environmental regulations. The increasingly severe restrictions on the levels of SOX, NOX, CO2 and other emissions from the combustion of heavy fuels has led to decreased demand for residual fuel oil products. Additionally, the increased availability and use of natural gas as fuel for power plants has compounded the decreased demand for fuel oil. Figure 1 shows the total world demand growth for crude and petroleum products from 1999 to 2010.