Abstract: Chemical reactor with high speed rotary mixing, system thereof, and method thereof, for catalytic thermal conversion of organic (hydrocarbon-containing) materials (coal, plastics, rubber, plant matter, wood shavings, biomass, organic wastes) into diesel and other liquid fuels (automobile or/and jet engine fuels). Relevant to non-conventional commercial scale production of liquid fuels, and to commercial scale processing and disposing of organic waste materials. Chemical reactor includes: integrated combination of a reactor stationary assembly (RSA), having only stationary components remaining stationary during chemical reactor operation, and a reactor rotary mixing assembly (RRMA), having only rotatable components rotating during chemical reactor operation. May include anti-abrasion shield for shielding inner surface of reactor central housing from abrasion during chemical reactor operation. Rotor may include a reinforcement disc.

Abstract: A chemical reaction apparatus includes a horizontal flow-type reactor in which a content horizontally flows with an unfilled space being provided thereabove, a microwave generator that generates microwaves, and at least one waveguide that transmits the microwaves generated by the microwave generator to the unfilled space in the reactor.

Abstract: Chemical reactor with high speed rotary mixing, system thereof, and method thereof, for catalytic thermal conversion of organic (hydrocarbon-containing) materials (coal, plastics, rubber, plant matter, wood shavings, biomass, organic wastes) into diesel and other liquid fuels (automobile or/and jet engine fuels). Relevant to non-conventional commercial scale production of liquid fuels, and to commercial scale processing and disposing of organic waste materials. Chemical reactor includes: integrated combination of a reactor stationary assembly (RSA), having only stationary components remaining stationary during chemical reactor operation, and a reactor rotary mixing assembly (RRMA), having only rotatable components rotating during chemical reactor operation. May include anti-abrasion shield for shielding inner surface of reactor central housing from abrasion during chemical reactor operation. Rotor may include a reinforcement disc.

Abstract: A slurry bubble column reactor with a gas distribution arrangement comprising an upper sparger, a lower sparger, and an open-ended tube. Gas from the lower sparger enters the tube and lowers the density of slurry in the tube. The difference in slurry density causes the slurry in the tube to rise, causing slurry outside the tube to move down, maintaining circulation and flushing catalyst from the vessel wall.

Abstract: The present invention is concerned with a fluid circulation apparatus for use as a bioreactor or the like, the apparatus comprising a flexible bag like container within which is disposed a collapsible and at least partially inflatable draft tube which is tethered to a base of the container such that when inflated the draft tube rises off the base and maintains the correct shape as a result of the inflation thereof, and which includes perforations in order to allow the inflation gas to escape and rise upwardly through the draft tube to generate counter current circulation within the container.

Abstract: An apparatus for mixing viscous material includes a chamber having a cylindrical sidewall and a bottom and receiving viscous material to be mixed; a cylindrical draft tube fixed at an inside center of the chamber to be spaced from the bottom and the sidewall and forming a space between the draft tube and the sidewall to allow passage of the viscous material, and including a heat medium passage therein; a carrying impeller installed in the draft tube and driven by a motor to transfer the viscous material above or below the draft tube and suck the viscous material in the space into the draft tube; and a sweeping impeller installed in the space and rotated in a circumferential direction by a motor to apply a pressure to the viscous material so that the viscous material in the space is not adhered to the draft tube and the sidewall.

Abstract: The present invention relates to a slurry bed loop reactor comprising a riser and at least one downcomer (3), wherein two ends of the riser are connected to two ends of the downcomer (3) via lines (16) and (7), respectively. The riser comprises a reaction section (1) and a settling section (2) with an increased tube diameter disposed on the reaction section (1). A gas outlet (13) exists at the top of the settling section (2). Each of the downcomers (3) is divided into a filtrate section (5) and a slurry section (6) by filter medium (4), wherein the filtrate section (5) is connected to a liquid outlet (10); two ends of the slurry section (6) are respectively connected to two ends of the riser, and the filtrate region (5) may further be connected to a back purging system.

Abstract: A gasification system is disclosed having a combustion or reaction vessel, a scrubber housing, and a filter housing. A carbonaceous fuel is partially combusted in the reaction vessel to generate a combustible gas. An improved ash support and removal system reduces clogging and other problems in the reaction vessel. The combustible gas passes through the scrubber housing to remove matter such as tar and oil, and the scrubbed gas passes through a hybrid blower to the filter housing. Wood chips are used in the filter housing to provide a relatively clean, dry gas. Wastewater and other waste products from the scrubber housing and filter housing are captured and returned to the reaction vessel.

Abstract: Disclosed is a reactor for separating an aluminum layer from multi-layer film wastes to reuse a multi-layer film waste without burying or incinerating the multi-layer film waste including the aluminum. The reactor comprises a cylindrical casing which is filled with a solution to dissolve aluminum layers of the multi-layer film wastes pulverized into a predetermined size, a partition dividing an inner portion of the casing into a reactor tub in which the solution reacts with the aluminum layer and a separator tub which is provided at a portion of the reactor tub to decompose the pulverized multi-layer film wastes in which the aluminum is completely dissolved by the solution, and a stirrer which is installed at an upper portion of the reactor and stirs the solution in the reactor to activate the reaction between the solution and the aluminum in the reactor tub and to transfer the multi-layer film wastes to the separator tub.

Abstract: Method of combustion with a gas burner having a burner head at one end of an inner gas pipe surrounded by an outer protective pipe, wherein gases from the burner head flow inside the inner pipe and inside the outer pipe and thereafter flow into an exhaust channel. The inner pipe terminates short of the burner head; a sleeve downstream of the burner head, is inserted into and/or placed concentrically with the inner pipe so that the sleeve orifice is located within the inner pipe; a gap is provided between the opening of the inner pipe and the sleeve. The gap is sized such that the mixture of fuel and combustion air from the burner head and recycled exhaust gases passing through the gap will be mixed in quantities at which the temperature of combustion will be lower than the temperature in which NOx is formed.

Abstract: In an upflow reactor for reacting heavy hydrocarbons with hydrogen gas in a liquefied catalyst slurry, that mixture is recirculated down through a downcomer having an upper degassing section which includes a frusto-conical upper surface. The mixture is caused to flow along that surface in a downward helical path, such that heavier components are centrifugally urged outwardly, and lighter components, e.g., gas, migrate inwardly. The gas bubbles can thus coalesce such that small bubbles become bigger bubbles having a greater tendency to rise out of the downcomer. Baffles placed on the upper surface can maximize the residence time of the mixture in the degassing section.

Abstract: A gasification system having a combustor vessel, an optional scrubber vessel, an optional fixer vessel, an optional cyclone vessel and an optional demister vessel. A wide variety of possibly moist solid or semi-solid carbonaceous fuels may be partially combusted in the combustor to generate a combustible gas and a mineral ash. An improved ash support and removal subsystem reduces clogging and other problems. The combustible gas is conveyed by optional heavy-duty blowers through the optional vessels to remove liquids and particulates and to undergo catalytic chemical reactions to provide a relatively clean, dry, highly-combustible hydrocarbon gas that captures a relatively high fraction of the potential heating value of the fuel. Internal gases, liquids and particulates from the vessels may be recycled inside the system to improve efficiency and prevent liquid waste. A portion of the internal liquids may also be extracted for other uses.

Abstract: A downcomer for a reactor for downwardly conducting a multi-phase mixture, the downcomer includes a transport section having an interior comprised of inner and outer regions separated horizontally by a vertical barrier, and a baffle structure disposed on an inner surface of the barrier. The baffle structure is arranged to induce the mixture to flow in a downward generally helical path such that denser components of the mixture are centrifugally urged outwardly away from a center of the downcomer and less dense components migrate toward the center. The barrier includes openings enabling the denser components to travel from the inner region to the outer region to be collected herein.

Abstract: A method and apparatus for treating wastewater. The apparatus comprises a reactor having a flow channel generally centrally located in a reactor and immersed in the water or wastewater in the reactor. An agitator is disposed within the flow channel and induces water or wastewater to enter the open upper end thereof and to move downwardly through the flow channel where the water or wastewater is discharged via a flow divider. A reagent is injected into the water or wastewater and the agitator within the flow channel serves to mix the reagent with the water or wastewater passing therethrough and in the process causes at least a slightly turbulent and downward axial flow through the flow channel.

Abstract: The invention relates to improvements in internal loop reactors. The reactor of the invention is characterized by a plurality of cooling tubes which form the annulus between the riser and the downcomer path of said internal loop reactor. The reactor also provides improvements in hydroformylation reactions using the improved reactor.

Abstract: The invention relates to improvements in internal loop reactors. The reactor of the invention is characterized by a plurality of cooling tubes which form the annulus between the riser and the downcomer path of said internal loop reactor. The reactor also provides improvements in hydroformylation reactions using the improved reactor.

Abstract: A method for producing aniline or toluenediamine is disclosed which comprises forming a dispersion comprising hydrogen gas bubbles dispersed in a liquid medium comprising either nitrobenzene or dinitrotoluene, wherein the hydrogen gas bubbles have a mean diameter less than 1 micron; and subjecting the dispersion to hydrogenation reaction promoting conditions comprising pressure less than about 600 kPa and temperature less than about 200° C., whereby at least a portion of the nitrobenzene or dinitrotoluene is hydrogenated to form aniline or toluenediamine, respectively. A system for carrying out the method is also disclosed.

Abstract: A unique reactor configuration especially suitable for interphase mass transfer and mixing of multiple phases, i.e. gas(es), liquid(s), and solid(s) where reaction is catalyzed by a solid catalyst comprises a draught tube reactor wherein the solid catalyst particles are maintained in an annular space between the draught tube of the reactor and an annulus-defining wall by means of filter elements positioned downstream and optionally also upstream from the catalyst bed.

Abstract: The present invention also relates to a fluid processing device using material pieces, which is usable for processing liquid and gas. The hexagon nut shaped material pieces of stainless steel and the like are heat-treated and oriented such that the material pieces form up into a kind of concentric circles and make single plane, with drawing lines linked the center points of the hexagonal nut shaped material pieces positioned the outermost circumferentially periphery of the concentric arrangement forming up into an equilateral hexagon and such arrangement is retained. Also, a fluid processing device comprises a hollow container that such field converter is positioned in.

Abstract: A system and method for mixing high viscous liquids with gas is provided. The disclosed embodiments include a reactor or mixing vessel having a draft tube disposed therein, a gas injection subsystem adapted to inject gas into the reactor or mixing vessel proximate the entrance of the draft tube. The embodiments also include an agitator disposed within the draft tube which makes the draft tube the primary site for the gas-liquid mixing. In particular, the agitator is adapted to create gas bubbles having an average diameter between about 0.3 mm and 3.0 mm which are then ejected into the reactor or mixing vessel. The mass transfer efficiency associated with the present system and method is enhanced from the combined effect of gas dissolution into the high viscous liquid within the draft tube and greater bubble residence time within the high viscous liquid.

Abstract: The invention relates to improvements in internal loop reactors. The reactor of the invention is characterized by a plurality of cooling tubes which form the annulus between the riser and the downcomer path of said internal loop reactor. The reactor also provides improvements in hydroformylation reactions using the improved reactor.

Abstract: A unique reactor configuration especially suitable for interphase mass transfer and mixing of multiple phases, i.e. gas(es), liquid(s), and solid(s) where reaction is catalyzed by a solid catalyst comprises a draught tube reactor wherein the solid catalyst particles are maintained in an annular space between the draught tube of the reactor and an annulus-defining wall by means of filter elements positioned downstream and optionally also upstream from the catalyst bed.

Abstract: Disclosed is a process for reacting feed in and an apparatus comprising a radial flow reactor including a first catalyst bed disposed between an outer wall and a centerpipe of the vessel and a second catalyst bed disposed within a centerpipe. Also disclosed is a method of loading catalyst into the radial flow reactor.

Abstract: A gas siphon type reactor (10) is used to carry out a three phase chemical reaction under pressure, such as the reduction of uranyl nitrate to uranous nitrate by hydrogen, in the presence of a catalyst made up of platinum on a silica carrier. The control of the pressure in the reactor (10) is provided by regulating the liquid and gas flow rates from separator (52), into which the liquid and the gas leaving the reactor (10) are routed. The liquid in the reactor (10) is tapped from a lateral branch pipe (32) fitted with a filter (36) and emerging in the upper area (30), behind a profiled wall (34).

Abstract: The invention relates to a method and a mixer for mixing flows of a papermaking process. In the invention, a first flow is conveyed through a tube, and turbulence is generated in it by means of form parts located on the inner periphery of the tube. The mixing zone of the mixer comprises feed openings on the inner periphery of the tube for feeding a second flow from a feed channel outside the tube into the first flow, whereby the flows are mixed as a result of the turbulence generated by the form parts. According to a preferred embodiment of the invention, at least one form part comprises a feed opening.

Abstract: A unique reactor configuration especially suitable for interphase mass transfer and mixing of multiple phases, i.e. gas(es), liquid(s), and solid(s) where reaction is catalyzed by a solid catalyst comprises a draught tube reactor wherein the solid catalyst particles are maintained in an annular space between the draught tube of the reactor and an annulus-defining wall by means of filter elements positioned downstream and optionally also upstream from the catalyst bed.

Abstract: A gasification reactor apparatus (10) comprising a gasification vessel (12), a gas-fired combustion chamber (70) and a combination fan and cyclone unit (20) in an upper part (12′) of the vessel (12) with two functions: first, the fan (62, 64) impels incoming feedstock (14, 14′) centrifugally into contact with the hot inside surface of the vessel to produce rapid onset of gasification. Second, the unit (20) exerts a cyclonic motion on the product gas causing outward separation of particulate matter from the gas, which passes to the outlet via a path through the middle of the vessel (12).

Abstract: An axial conveyor is described, in particular for conveying gas/liquid dispersions, wherein the conveying elements comprise a wall-sweeping edge pointing in the direction of the pressure side of the conveying elements. The axial conveyor is particularly suitable as a circulating member in loop reactors. A process comprising conveying gas/liquid dispersions as well as a process for carrying out chemical reactions directly reacting gas with gases not completely dissolved in a liquid medium, or optionally in the presence of finely divided solids, through the use of an axial conveyor, is also disclosed.

Abstract: A multi-stage loop reactor, employed in various gas-liquid or gas-liquid-solid chemical reaction systems, which comprises a reactor body, draft tube(s) inside the reactor body, and a gas distributor at the bottom of draft tube. The draft tube can include one or more sections. The multi-stage loop reactor of the present invention has a higher mass transfer rate because the different phases are well mixed throughout the reactor, and the gas bubbles are distributed evenly everywhere. The reactor of this invention can be extensively applied in various gas-liquid or gas-liquid-solid reaction processes including the oxidization process, hydrogenation process, hydrocracking process, coal liquification process, fermentation process, hydrocarbon processing process, and biological treatment of waste water, etc.

Abstract: A steam reformer for producing H2 from a low pressure hydrocarbon gas (preferably propane) using an improved gaseous hydrocarbon fuel and steam delivery system comprising two coaxial tubes, an outer tube for delivery of steam which is gradually reduced in diameter to form a truncated conical tip for the outflow of steam around the end of an inner tube for the outflow of gaseous hydrocarbon. The outflow ends of both tubes are positioned in the same plane perpendicular to their axis. The outflow end of the second tube is preferably also gradually reduced in diameter in order to provide higher velocity of gaseous hydrocarbon to be mixed with the steam entering the reformer for optimized yield of hydrogen by optimizing the mixing of the steam and gaseous hydrocarbon in order to optimize the yield of hydrogen for the optimized generation of wattage for the same fuel-cell power generating system.

Abstract: The invention provides processes and apparatus for producing hydrogen from water, including the steps of heating water to a water dissociating temperature to form a dissociated water reaction mixture comprising hydrogen gas and oxygen gas. A vortex is formed of the reaction mixture to subject the reaction mixture to a centrifugal force about a longitudinal axis of an interior space of a vortex tube reactor, so that there is radial stratification of the hydrogen gas and the oxygen gas in the interior space of the vortex tube reactor. Hydrogen or oxygen is preferentially extracted from the reaction mixture at spaced apart points along the length of the interior space of the vortex tube reactor.

Abstract: Arrangement for understoichiometric gasification of spent liquor from chemical pulp production, comprising an upper reactor part (2), which upper reactor part is provided with a burner (5) for the spent liquor and with an internally clad reactor jacket (4), and lower separating part (8) for separating a phase of solid and/or molten material, formed on gasification, from a phase of combustible gaseous material. According to the invention, at least the upper reactor part (2), with its clad reactor jacket, is surrounded by an outer vessel (1), with a gap (13) being present between the reactor jacket (4) and the outer vessel (1). Connected to the said gap (13) there are one or more inlets (14) and at least one outlet (21) for a coolant medium.

Abstract: A fluid contactor is taught for mixing and reacting of fluids. Mixing is enhanced by providing a suitable residence time and suitable surface area contact by forming eddy flow within the fluid and thereby the formation of vortexes. Such a contactor does not require the use of mechanical mixers. The contact chamber of the present invention can enhance chemical modification by use of chemical modifiers such as ultraviolet lamps, by allowing the positioning of such modifiers adjacent the vortexes.

Abstract: A mixer for preparing silver halide grains for photographic use has upper and lower impellers housed in a draft tube. The bottom impeller has flat blades for micromixing silver and halide reactants introduced into the bottom of the draft tube. The upper impeller has pitched blades for macromixing the bulk fluid. The impellers are spaced apart at least the distance of their diameters so that the upper and lower impellers operate independently of one another so that micromixing is independent of macromixing. A flow disrupter structurally associated with the draft tube and positioned above the top impeller prevents vortexing of the fluid during mixing. Baffles may be provided in the draft tube to discourage vortexing.

Abstract: A process for treating NF3 useful as a dry etching gas and cleaning gas in processes for producing LSI, TFT, and solar cell and in an electron photographic processes.

Abstract: Embodiments of a remediation reactor and mixer/contactor blade for the reactor are shown and described, the reactor (11) being for containing a liquid slurry, suspension or settled bed of solid particles containing microorganisms. Inside the vessel is a supply conduit and at least one generally horizontal stirrer blade (27) in fluid connection with the supply conduit. The stirrer blade is a mixer/contactor which has a leading side having openings through which fluid may pass. The stirrer blade rotates in the vessel, and this rotation is made easier by the hydraulic forces of fluid flowing out from the stirrer blade. The flowing fluid creates a fluidization zone in the slurry, suspension or settled bed at or near the leading edge of the stirrer blade. The fluidization zone is less dense than the rest of the sediment bed, and the stirrer blade tends to rotate into the fluidization zone.

Abstract: A downcomer for producing at least two slurries having different solids and gas concentrations from a single three phase slurry of particulate solids and gas bubbles in a slurry liquid has two or more concentric gas and solids disengaging zones, each having an open fluid conduit depending from an orifice in the bottom. The downcomer is useful in a slurry hydrocarbon synthesis process for forming a catalyst and gas reduced slurry which is passed to a liquid filter to remove hydrocarbon liquid from the slurry reactor.

Abstract: The present invention relates to an apparatus for the continuous manufacture of solid particles of alkali metal persalts by reaction of an aqueous hydrogen peroxide solution with an aqueous solution of an alkali metal salt and crystallization of the persalt. The persalt is formed in a crystallizer classifier, which is made up of stirred region and a growth region for the persalt crystals a non-stirred clarifying region for the solution and a classification region for the particles obtained by elutriation in a liquid stream withdrawn in the clarifying region.

Abstract: A method of separating a Fischer-Tropsch catalyst from the output slurry of a Fischer-Tropsch bubble column reactor, where the slurry comprises Fischer-Tropsch catalyst particles and liquid hydrocarbon product is disclosed. The method comprises contacting a compressed hydrocarbon solvent (e.g., a supercritical hydrocarbon solvent, or liquid hydrocarbon solvent which may be at near supercritical conditions) with the output slurry at a temperature and pressure where the liquid hydrocarbon product is soluble in the solvent to form a concentrated slurry phase containing the catalyst particles, and an enriched solvent phase containing liquid hydrocarbon product. This contacting step is then followed by the step of separating the concentrated slurry from the enriched solvent. Apparatus for carrying out the method of the invention is also disclosed.

Abstract: The invention relates to a reactor for the treatment of wastewater solutions containing cyanide and other dissolved organic material, having an elongated tube having an entrance (28) and an exit (32), and an energy source (22) for the tube, preferably positioned adjacent the exit. The energy source generates intense energy such that a cyanide/organic material-containing solution can be treated by passing it through the tube to expose it to said energy so that the solution absorbs sufficient energy from the energy source to degrade the cyanide and/or dissolved organic material contained therein. The source of intense energy is preferably a plasma, e.g. a plasma generated by a plasma torch or a DC electric arc. The invention also relates to a process of treatment of such a wastewater solution by passing it through such a reactor.

Abstract: A method is provided for zeolite synthesis from a synthesis medium containing in particular a trivalent aluminum source, a tetravalent silicon source, at least an alkaline or alkaline-earth cation in hydroxide form and water in a reactor containing a solid helical moving body in a guiding tube defining an internal space and a space external to the tube. The invention is characterized in that the synthesis medium is circulated in the reactor in a continuous flow passing through the internal space then the space external to the tube and returning to the internal space, only driven by the roation of the solid helical moving body, at a speed of less than 500 rpm, in the tube which is kept fixed, the synthesis medium being kept at a temperature suitable for at least one of the ripening operations or the crystal growth of the synthesized zeolite. The invention also is directed to a device for implementing the method.

Abstract: Provided is a quench vessel containing at least two separate internal vessels. A receiving liquor is contained in the first internal vessel and a washing liquid bath is contained in a second internal vessel.

Abstract: The first agitating impeller and the second agitating impeller, which are arranged in the addition solution mixing chamber dipped in the primary component solution stored in the reaction vessel, are rotated independently from each other in the reverse direction, so that the generation of vortexes is suppressed.

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: A method for making zinc bromide from metallic zinc and bromine comprising contacting zinc with bromine dissolved in a reaction solvent containing a metal halide salt. During the practice of this method, the reaction temperature is maintained at less than 60.degree. C. The reaction solvent preferably comprises an alkali, alkaline earth or transition metal halide and the halide salt preferably comprises a chloride or a bromide. One preferred method includes the step of recirculating the zinc bromide product stream back to the reaction vessel. The reaction vessel can comprise either a one stage or a multiple stage reactor. The resulting product stream comprises a high density zinc bromide solution.

Abstract: A mixing apparatus for mixing black liquor from cellulose production with ash from flue gases which is generated on combustion of black liquor. The mixing apparatus contains a cylindrical tank, a stirrer mechanism having a propeller secured on the upper part of a vertical shaft, rotating baffles secured on the lower part of the shaft, and stationary, vertical, radial baffles arranged around, and at a distance from, the rotating baffles. The invention also provides a method for mixing black liquor and ash.

Abstract: Provided is a process for recovering chemicals and energy from spent liquor obtained when producing paper pulp by chemical delignificatation of fibrous raw material. The spent liquor is gasified in at least two reactors, a first and a second stream of solid and/or smelt material and of combustible gaseous material being formed. The formed material is treated in one or more devices (5, 6, 7, 8), whereby a first (9) and a second liquor (27) are formed. The pressure and/or temperature in the first reactor differ(s) from the pressure and/or temperature in the second reactor. In addition, one or more process chemicals are recovered selectively from the formed liquor and/or gas, and are thereafter returned in whole or in part to one or more of the reactors (1, 2) and/or to one or more of the devices (5, 6, 7, 8) for treatment of the formed material.

Abstract: This invention relates to a reactor 1 for the continuous production of linear or cyclic acetals, in particular trioxane, dioxolane, tetroxane, dimethoxymethane, diethoxymethane, diethoxyethane and dibutoxyethane. This reactor has internal adjacently arranged evaporator elements 2, which allow for flow-through of a heat transport medium, and which are at least two meters high so as to generate a thermosiphon flow. The clear cross section between the evaporator elements is 20 to 80% of the overall cross section. Using the reactor, circulation ratios of up to 250 can be achieved. Thus, the reliability and availability of a production plant is increased while the susceptibility to breakdown decreases.

Abstract: A reactor for corrosive and abrasive reaction mixtures having an upper setion and a conically tapered lower reaction section, with a screw mixer consisting of a jacketed band surrounding a conveyor screw, suspended fron the top of the reactor, and an inlet for solid reactants which leads directly into the vertical conveying device.

Abstract: The operation of a hydrocarbon synthesis reactor and catalyst distributed in the reaction slurry therein are improved by the presence in said reactor of one or more vertical downcomers open at both ends with gas disengaging areas located at their top end. The downcomer which circulates catalyst from the top of the reaction slurry to the bottom of said slurry is fully immersed in the reaction slurry and preferably extends from just above the bottom of the reaction zone of the reaction vessel to just below the top surface of the reaction slurry. The bottom end of said downcomer is shielded from intrusion of rising synthesis gas by the placement of a baffle which blocks rising gas entry but facilitates the exit of catalyst and liquid from the bottom of said downcomer and distributes them radially throughout the adjacent reactor slurry.