Abstract: Fischer-Tropsch synthesis is performed using a compact catalytic reactor unit (10) defining channels in which is a gas-permeable catalyst structure (16), the channels extending between headers (18). The synthesis occurs in at least two stages, as the reactor unit provides at least two successive channels (14, 14a) for the Fischer-Tropsch synthesis connected by a header, the gas flow velocity through the first channel being sufficiently high that no more than 65% of the carbon monoxide undergoes conversion. The gases are cooled (25) in the header between the two stages, so as to condense water vapor, and then pass through the second channel at a sufficiently high gas flow velocity that no more than 65% of the remaining carbon monoxide undergoes conversion. This lowers the partial pressure of water vapor and so suppresses oxidation of the catalyst.

Abstract: A catalytic reactor comprises a plurality of sheets defining flow channels between them. Within each flow channel is a foil of corrugated material whose surfaces are coated with catalytic material. Flow channels for a first gas extend in oblique directions relative to the flow channels for a second gas. The reactor incorporates header chambers to supply gas mixtures to the flow channels, the headers communicating with adjacent channels being separate. The reactor enables different gas mixtures to be supplied to adjacent channels, which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets separating the endothermic reaction. When the catalyst in one set of flow channels becomes spent, it can be replaced by removing a header.

Abstract: A fuel gas is passed into one set of channels in a compact reactor (12) consisting of a plurality of metal sheets (41) arranged to define first and second gas flow channels (14 and 15), the channels being arranged alternately to ensure good thermal contact between the gases in them and each channel containing a removable metallic heat conducting insert (44) coated with a ceramic. In the set of channels carrying the fuel the ceramic supports particles of a transition metal oxide, which is reduced by the combustion gas to form metal particles. In the other set of channels the ceramic supports particles of a transition metal, and these channels carry a flow of an oxidizing gas, which oxidises the metal. The flows to the two sets of channels are then exchanged. If the oxidizing gas is steam, the result is a stream of pure hydrogen.

Abstract: A catalytic reactor comprises a stack of sheets defining flow channels between them. Within each flow channel is a flexible wire structure whose surfaces are coated with catalytic material. Flow channels for a first gas extend along S-shaped curved paths whereas the flow channels for a second gas are straight. The reactor incorporates header chambers to supply gas mixtures to the flow channels, each header chamber being a rectangular cap attached to a face of the stack. The reactor enables different gas mixtures to be supplied to adjacent channels, which nay be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets separating the adjacent channels, from the exothermic reaction to the endothermic reaction. When the catalyst in one set of flow channels becomes spent, it can be replaced by removing a header.

Abstract: Natural gas is processed to generate longer-chain hydrocarbons, the process comprising subjecting the gas to steam reforming to generate a mixture of carbon monoxide and hydrogen, and then subjecting this mixture to Fischer-Tropsch synthesis. The Fischer-Tropsch synthesis is performed at an elevated temperature above 230° C. and with a gas hourly space velocity greater than 10 000 hr?1 so as to achieve a selectivity to the production of C5+ hydrocarbons that is less than 65%. The resulting liquid product can be used as a vehicle fuel, while the tail gases may be used to generate electricity.

Abstract: Methane is reacted with steam, to generate carbon monoxide and hydrogen in a first catalytic reactor; the resulting gas mixture can then be used to perform Fischer-Tropsch synthesis in a second catalytic reactor. In performing the steam/methane reforming, the gas mixture is passed through a narrow flow channel containing a catalyst structure on a metal substrate, and adjacent to a source of heat, in a time less than 0.5 s, so that only those reactions that have comparatively rapid kinetics will occur. Both the average temperature and the exit temperature of the channel are in the range 750° to 900° C. The ratio of steam to methane should preferably be 1.4 to 1.6, for example about 1.5. Almost all the methane will undergo the reforming reaction, almost entirely forming carbon monoxide. After performing Fischer-Tropsch synthesis, the remaining hydrogen is preferably used to provide heat for the reforming reaction.

Abstract: A valve assembly (10) comprises a valve stem (14) with a bore (15) and radial apertures (17), and a sleeve (18) closed atone end and slidable over the valve stem (14) to obstruct the apertures (17). At the end of the valve stem opposite the outlet end, the valve stem (14) defines a fluidic vortex chamber (22) with both tangential inlets (28) and non-tangential peripheral inlets (26), and with an axial outlet (24) communicating with the bore (15). The sleeve (18) defines at least one radial port (32) near its closed end. The valve assembly operates in a conventional fashion except when approaching closure. Once the last of the apertures (17) in the valve stem has been closed, the only flow path is through the fluidic vortex chamber (22). Further movement of the sleeve (18) alters the distribution of the flow between the non-tangential inlets (26) and the tangential inlets (28), so adjusting the strength of the fluidic vortex and the resistance to fluid flow.

Abstract: Fischer-Tropsch synthesis is performed on a CO/H*2 feed gas using a plurality of compact catalytic reactor modules (12) each defining catalytic reaction channels and coolant channels, in two successive stages, with the same number of reactor modules for each stage. The gas flow velocity in the first stage is sufficiently high that no more than 75% of the CO undergoes conversion. The gases are cooled (16) between successive stages so as to remove water vapour, and the pressure is reduced (20) before they are subjected to the second stage. In addition the reaction temperature for the second stage is lower than for the first stage, such that no more than 75% of the remaining carbon monoxide undergoes conversion during the second stage too. The deleterious effect of water vapour on the catalyst is hence suppressed, while the overall capacity of the plant (10) can be adjusted by closing off modules in each stage while keeping the numbers equal.

Abstract: Natural gas is processed to generate longer-chain hydrocarbons, the process comprising subjecting the gas to steam reforming to generate a mixture of carbon monoxide and hydrogen, and then subjecting this mixture to Fischer-Tropsch synthesis. The reforming reaction (20) is performed at 0.4–0.5 MPa and the Fischer-Tropsch synthesis (50) at 1.8–2.1 MPa, and two compressors (36, 44) are used to raise the pressure, the gas mixture being cooled (26, 32, 40) before and after the first compressor (36). This reduces both the operating cost and capital cost of the plant.

Abstract: A valve system (10) controls the fluid flow between an inlet (12) and an outlet (14). The system (10) splits the flow into two parallel flow ducts (15, 16) and recombines the flows through opposed tangential inlets (18) and (19) of a fluidic vortex valve (20) which has an axial outlet (22). An adjustable valve (24) controls the flow through one of the parallel flow ducts (15), controlling the strength of the vortex generated within the vortex valve (20). Hence a small valve (24) can control and adjust the flows in both ducts (15 and 16).

Abstract: Small crystals are made by mixing a solution of a desired substance with an anti-solvent in a fluidic vortex mixer in which the residence time is less than 1 s, for example 10 ms. The liquid within the fluidic vortex mixer (12) is subjected to high intensity ultrasound from a transducer (20, 22) in or on the wall of the mixer, or coupled to a pipe supplying liquid to the mixer. The solution very rapidly becomes supersaturated, and the ultrasound can induce a very large number of nuclei for crystal growth. Small crystals, for example less than 5 ?m, are formed that may be of a suitable size for use in inhalers.

Abstract: A chemical plant for performing a chemical reaction between particles of a material such as lithium metal, and a reagent such as butyl chloride in solution in hexane, in which one reaction product is a solid material, includes a reaction vessel (12). Several ultrasonic transducers (16) are attached to a wall of the vessel (12) so as to irradiate ultrasonic waves into the vessel, the vessel being large enough that each transducer irradiates into fluid at least 0.1 m thick, each transducer irradiating no more than 3 W/cm2, and the transducers being sufficiently close to each other and the number of transducers being sufficiently high that the power dissipation within the vessel is at least 10 W/liter but no more than 200 W/liter. The high intensity of ultrasound ensures that lithium chloride is cleaned off the surface of lithium metal particles throughout the vessel (12).

Abstract: A catalytic reactor (10) comprises a stack of sheets (12) defining flow channels (14) between them. Within each flow channel (14) is a flexible wire structure (16) whose surfaces are coated with catalytic material. Flow channels (14, 14a) for a first gas extend along S-shaped curved paths whereas the flow channels (14b) for a second gas are straight. The reactor (10) incorporates header chambers (18) to supply gas mixtures to the flow channels (14), each header chamber being a square cap attached to a face of the stack. The reactor (10) enables different gas mixtures to be supplied to adjacent channels (14), which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the sheets (12) separating the adjacent channels (14), from the exothermic reaction to the endothermic reaction.

Abstract: A valve assembly (10) comprises a vortex chamber (14) with an axial outlet port (20), a main inlet port (16) for a fluid to be controlled, and a substantially tangential inlet port (25); the fluid enters through an inlet chamber (13) in which is a mechanical valve (26) movable so as to obstruct fluid flow into the vortex chamber (14). A duct (24) links the inlet chamber (13) to the tangential inlet port (25) of the vortex chamber. The position of the mechanical valve (26) affects the flow of fluid through the duct (24), so the vortex chamber (14) amplifies the effect of the mechanical valve. Further movement of the valve (26) closes off flow altogether (40). The assembly may include a weir (36) in the outlet, to separate gas and liquid phases.

Abstract: Small crystals are made by mixing a solution of a desired substance with an anti-solvent in a fluidic vortex mixer in which the residence time is less than 1 s, for example 10 ms. The liquid within the fluidic vortex mixer (12) is subjected to high intensity ultrasound from a transducer (20, 22) in or on the wall of the mixer, or coupled to a pipe supplying liquid to the mixer. The solution very rapidly becomes supersaturated, and the ultrasound can induce a very large number of nuclei for crystal growth. Small crystals, for example less than 5 &mgr;m, are formed that may be of a suitable sise for use in inhalers.

Abstract: A chemical plant for performing a chemical reaction between particles of a material such as lithium metal, and a reagent such as butyl chloride in solution in hexane, in which one reaction product is a solid material, includes a reaction vessel (12). Several ultrasonic transducers (16) are attached to a wall of the vessel (12) so as to irradiate ultrasonic waves into the vessel, the vessel being large enough that each transducer irradiates into fluid at least 0.1 m thick, each transducer irradiating no more than 3 W/cm2, and the transducers being sufficiently close to each other and the number of transducers being sufficiently high that the poser dissipation within the vessel is at least 10 W/litre but no more than 200 W/litre. The high intensity of ultrasound ensures tat lithium chloride is cleaned off the surface of the lithium metal particles throughout the vessel (12).

Abstract: A catalytic reactor (10) comprises a plurality of fluid-impermeable elements (tubes or plates) (12) defining flow channels (15) between them. Tight fitting within each flow channel (15) is a sheet (16) of corrugated material whose surfaces are coated with catalytic material. At each end of the reactor (10) are headers (18) to supply gas mixtures to the flow channels (15), the headers communicating with adjacent channels being separate. The reactor (10) enables different gas mixtures to be supplied to adjacent channels (15), which may be at different pressures, and the corresponding chemical reactions are also different. Where one of the reactions is endothermic while the other reaction is exothermic, heat is transferred through the wall of the tube (12) separating the adjacent channels (15), from the exothermic reaction to the endothermic reaction.

Abstract: A method of, and apparatus for, preventing the formation of deposits on surfaces downstream of a mixer in which possibly supersaturated mixtures issuing from the mixer are surrounded by a sheath of unsaturated solution. In an arrangement described, the sheath of unsaturated mixture is obtained by bleeding off some of the mixture issuing from the mixer sufficiently downstream of the mixer definitely to be unsaturated and returning this portion of the mixture to surround that issuing from the mixer.

Abstract: Apparatus for the on-line treatment of chemical reagents, including a flow line for a reagent flow, a vortex mixer in the flow line for combining and mixing the reagent flow with at least one further reagent flow, a pulser in the flow line for causing the pulsing of the mixed flow from the vortex mixer, and a vessel having an array of vortex cells for receiving the pulsing mixed flow to cause development and growth of precipitate under narrow residence time distribution conditions. Flow lines mix a flow of reagents to initiate precipitation. The pulser pulses the admixed reagents and causes the pulsing mixed flow to swirl with a constantly reversing rotational flow to achieve development and growth of precipitate.