The world’s first commercial plant to produce middle distillates from natural gas was started up by Shell in April 1993. The $660-million unit is built next to the Bintulu liquefied natural gas plant in the State of Sarawak, Malaysia. From 100 million cubic feet per day of natural gas feedstock, the daily output of liquid fuels is approximately 12,500 barrels per day.
The Shell Middle Distillates Synthesis (SMDS) process is based on modernized Fischer-Tropsch (F-T) technology which reacts an intermediate synthesis gas with a highly active and selective catalyst. The Shell catalyst minimizes coproduction of light hydrocarbons, unlike classical F-T catalysts. The plant has operating flexibility so that while maintaining maximum output, the composition of the product package, which will contain low molecular weight paraffins and waxes, can be varied to match market demand.
Since 1994, due to low prices for distillate fuels, Shell has shifted production toward higher-valued wax products, solvents, detergent feedstocks and waxy raffinates.
In December 1997 the plant was disabled by an explosion and fire. The plant is being reconstructed to be fully operational by April 2000.
In the process of reconstructing, Shell is planning to increase the plant’s capacity by 25 percent. Second-generation catalysts and an innovative exhaust gas turbine are two of the new technology developments under way.
The turbine would burn some of the low-BTU off-gas from the Heavy Paraffins Synthesis (HPS) process units, supplemented by natural gas.
Shell’s second-generation HPS catalyst is expected to produce more F-T wax than the first-generation catalyst. Shell wants more output of F-T wax because Shell can realize a premium on this wax compared to middle distillates. In addition to the new catalyst, larger reactors will be used, bringing output capacity to 9,000 barrels per day per multitubular reactor.
Shell will also increase reactor capacity in its Shell Gasification Process (SGP) unit. Each SGP unit processes 20 million cubic feet per day of gas, converting over 95 percent of the methane into carbon monoxide.