Shell partial oxidation process

Figure 14 Shell partial oxidation process flow diagram.

Shell operated its middle-distillate synthesis process (SMDS) in Malaysia from 1993 to 1997, but closed the facility in 1997 while better Fischer-Tropsch catalysts were being developed for future operation. Synthesis gas produced by the Shell partial oxidation process was converted to dhstillates and waxes in a tubular high-pressme Fischer-Tropsch reactor. A sluny phase reactor using an improved catalyst is being developed (40-46 atm 120-130°C). 

ER E discussions with Texaco and with Shell on bottoms processing are summarized herein. Texaco has indicated that its partial oxidation process could be applied to coal liquefaction bottoms on a commercial scale and that operation of their 12 T/D pilot plant with coal liquefaction bottoms representative of a projected commercial feedstock would be adequate to set the design basis for a commercial facility. Texaco indicated that three to four years after successful operation of the 12 T/D unit a commercial facility could be ready for startup. In initial discussions, Shell has indicated that development of the Shell/ Koppers partial oxidation process for coal liquefaction bottoms would involve operations of both their 6 T/D pilot plant and their 150 T/D demonstration unit. It was estimated that the 150 T/D facility might become available in the late 1980/early 1981 time frame for possible operation on vacuum bottoms. 

The Entrained system is a high temperature, high reaction rate process in which coal, oxygen (or air) and steam combine rapidly to produce LBG or MBG. The commercial processes aim primarily at the use of oxygen. Several developmental processes use oxygen or air. The most widely used commercial process (Koppers-Totzek) is operated at atmospheric pressure. The Texaco partial oxidation process used with oil and gas is under development for use with coal. Shell and Koppers are developing a pressurized version of the current Koppers-Totzek process. The advantages of the entrained... 

Combinations of physical and chemical absorption are also used, as in Shell s Sulfinol process in which a mixture of diisopropanolamine and sulfolane in water is utilized. For the hydrogen sulfide-free gases from the steam-reforming process, chemical scrubbing with activated potassium carbonate solutions or alkanolamines is preferred. In the case of hydrogen sulfide-containing gases from the partial oxidation process, physical absorption alone or in combination with chemical absorption is preferred. 

The current producers of partial oxidation processes are BASF, Texaco, Shell, and Hydrocarbon Research. A process block diagram showing the three process steps can be seen in Figure 2.18 [30]. The first step is the gasification process with the addition of oxygen and water. A detailed schematic of the Shell Gasification plant (SGP) is shown in Figure 2.19 [28]. The most important features of the process are the reactor, waste-heat-boiler, carbon catcher,... 

Heavy Hydrocarbon BasedPartial Oxidation Processes, Two major partial oxidation processes are commercially available, the Shell process (38) and the Texaco process (39). Operating conditions in the gas generator vary from 1200 C to 1370 0 and from 3100 kPa to 8270 kPa (450—1200 psig). Generally, heavy oils are the hydrocarbon feeds however, the process can also accommodate feeds from natural gas to residual oils. 

Process Refinements. Handling the carbon slurry is an important aspect of partial oxidation processes. The traditional approach to handling the carbon slurry was to contact it with a hydrocarbon to retain the carbon, which could thus be recycled to the reactor. The early Shell units used fuel oil as the extraction medium. This allowed atmospheric operation, providing a plant with low investment costs and, at least initially, low operating costs as well. The economics of this approach deteriorated with heavier feedstocks. The pelletizing oil had to be purchased at a premium to the main... 

The principal partial oxidation processes are known as the Texaco, Shell, arxi Koppers-Toteek processes. The Koppers-Totzek process is also used for coal and will be described urxier that heading. The Shell and... 

Texaco processes are generally similar. The Shell gasifier operates at 3.5-6 MPa, and the Texaco gasifier operates up to 9 MPa, Figure 6.19 is a flow diagram of the partial oxidation process. 

Development and Current Status. Development of the Shell gasification process for partial oxidation of oil and gas began in the early 1950s. More than 50 commercial Shell partial-oxidation plants have been built worldwide to convert a variety of hydrocarbon liquids and gases to carbon monoxide and hydrogen (1). This gas is most coromonly used as synthesis gas to produce high-value chemicals, such as ammonia and methanol. 

Non-catalytic partial oxidation is applied indnstrially by Texaco and Shell for the conversion of heavy oils to synthesis gas. In the ease of the Shell, basic partial oxidation process, liqnid fnel is fed to a reactor together with oxygen, and steam. A partial combustion takes place in the reactor, which yields a product at around 1150°C. It is this high temperature that poses a particular problem for conventional partial oxidation. The reactor has to be made of expensive materials to withstand the high temperatures, and the... 

Kramer G.J., Wieldraaijer W., Biesheuvel P.M., and Kuipers H.P.C.E. (2001) The determining factor for catalysts selectivity in shell s catalytic partial oxidation process , American Chemical Society, Fuel Chemistry Division Preprints, 46(2), 659-660. 

There are about a dozen gasification processes under development in this country and in Europe. A number of them have reached the stage of large pilot plants. The one that is probably closest to commercialization is the Texaco partial oxidation process. Texaco and Shell have both licensed partial oxidation processes for use with a variety of petroleum feeds since the late 19A0 s, and over 250 gasifiers have been installed, largely for making... 

The conversion of hydrocarbons with oxygen (reaction (5)) is done in the partial oxidation processes (Texaco, Shell) and also in a hybrid between thermal and catalytic reaction in an "autothermal reformer . 

Gas-adsorbent carbon. This is made by carbonization of coconut shells, fruit pits, coal, lignite, and wood. It must be activated, essentially a partial oxidation process, by treatment with hot air or steam. It is available in granular or pellet form and is used for recovery of solvent vapors from gas mixtures, gas masks, collection of gasoline hydrocarbons from natural gas, and the fractionation of hydrocarbon gases. It is reviviHed for reuse by evaporation of the adsorbed gas. 

Operation at very low temperatures with very sharp separations results in relatively complex flow schemes. This, combined with the need for low level refrigeration, leads to high plant costs. As a result, most applications of the Rectisol process represent relatively difficult gas treating conditions where other gas treating processes are not suitable for one reason or another. Typical applications are the purification of gas streams in the heavy oil partial oxidation processes of Shell and Texaco and the Lurgi coal gasification process, as used at the Sasol plants in South Africa. 

Successful commercialization of partial oxidation processes has been achieved by both Shell and Texaco. Figure 14 [17] displays a schematic of the Shell process, and Figure 15 [17] displays a schematic of the Texaco process. Both processes are similar. Commercial units based on Shell and Texaco partial oxidation processes (considered in total) number in the several hundreds. 

Strelzoff, S. (1974), Partial oxidation for syngas and fuel (comparaison des precedes Texaco, Shell et Union Carbide) . Hydrocarbon processing, Vol. 53, No. 12, p. 79. 

Oxidation Step. A review of mechanistic studies of partial oxidation of propylene has appeared (58). The oxidation process flow sheet (Fig. 2) shows equipment and typical operating conditions. The reactors are of the fixed-bed shell-and-tube type (about 3—5 mlong and 2.5 cm in diameter) with a molten salt coolant on the shell side. The tubes are packed with catalyst, a small amount of inert material at the top serving as a preheater section for the feed gases. Vaporized propylene is mixed with steam and ak and fed to the first-stage reactor. The feed composition is typically 5—7% propylene, 10—30%... 

ER E has studied these alternatives for the utilization of coal liquefaction bottoms in the production of hydrogen and fuel gas and in doing so has had discussions of partial oxidation with Texaco and Shell. These studies have identified a potentially attractive processing sequence utilizing FLEXICOKING to produce additional liquids and plant fuel, and partial oxidation to produce hydrogen. 

Non-catalytic partial oxidation (POX) of hydrocarbons from residual fuel oils to methane is commercially proven by two processes, one offered by Texaco and the other by Shell. Davy has experience with both processes. Each process has a large number of plants in operation, with feeds varying from natural gas to high sulfur residual oil. (In fact, so long as the feedstock can be pumped, it is a suitable feestock for a partial oxidation gasifier. 

The noncatalytic partial oxidation of hydrocarbons by the Shell gasification process (SGP) takes place in a refractory-lined reactor that uses a specially designed burner. The oxidant is preheated and then mixed with steam... 

Fif. 1.7. Hydrogen munuracturu hy partial oxidation. Shell process. 

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