EP1562697A1 - MISCHVORRICHTUNG F R ZWEIPHASEN-PARALLELSTROMBEHûLTER - Google Patents

MISCHVORRICHTUNG F R ZWEIPHASEN-PARALLELSTROMBEHûLTER

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Publication number
EP1562697A1
EP1562697A1 EP03769259A EP03769259A EP1562697A1 EP 1562697 A1 EP1562697 A1 EP 1562697A1 EP 03769259 A EP03769259 A EP 03769259A EP 03769259 A EP03769259 A EP 03769259A EP 1562697 A1 EP1562697 A1 EP 1562697A1
Authority
EP
European Patent Office
Prior art keywords
flow
mixing
velocity
reactor
phase
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP03769259A
Other languages
English (en)
French (fr)
Inventor
Morten MÜLLER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Morten Mueller Ltd Aps
Original Assignee
Morten Mueller Ltd Aps
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Morten Mueller Ltd Aps filed Critical Morten Mueller Ltd Aps
Publication of EP1562697A1 publication Critical patent/EP1562697A1/de
Ceased legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D3/00Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14Fractional distillation or use of a fractionation or rectification column
    • B01D3/16Fractionating columns in which vapour bubbles through liquid
    • B01D3/18Fractionating columns in which vapour bubbles through liquid with horizontal bubble plates
    • B01D3/20Bubble caps; Risers for vapour; Discharge pipes for liquid
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20Mixing gases with liquids
    • B01F23/23Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/232Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using flow-mixing means for introducing the gases, e.g. baffles
    • B01F23/2323Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using flow-mixing means for introducing the gases, e.g. baffles by circulating the flow in guiding constructions or conduits
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40Static mixers
    • B01F25/42Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions
    • B01F25/421Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions by moving the components in a convoluted or labyrinthine path
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/04Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds
    • B01J8/0446Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical
    • B01J8/0449Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical in two or more cylindrical beds
    • B01J8/0453Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds the flow within the beds being predominantly vertical in two or more cylindrical beds the beds being superimposed one above the other
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/04Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds the fluid passing successively through two or more beds
    • B01J8/0492Feeding reactive fluids
    • CCHEMISTRY; METALLURGY
    • C10PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10GCRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G49/00Treatment of hydrocarbon oils, in the presence of hydrogen or hydrogen-generating compounds, not provided for in a single one of groups C10G45/02, C10G45/32, C10G45/44, C10G45/58 or C10G47/00
    • C10G49/002Apparatus for fixed bed hydrotreatment processes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008Controlling the process
    • B01J2208/00017Controlling the temperature
    • B01J2208/00327Controlling the temperature by direct heat exchange
    • B01J2208/00336Controlling the temperature by direct heat exchange adding a temperature modifying medium to the reactants
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00796Details of the reactor or of the particulate material
    • B01J2208/00823Mixing elements
    • B01J2208/00831Stationary elements
    • B01J2208/00849Stationary elements outside the bed, e.g. baffles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00796Details of the reactor or of the particulate material
    • B01J2208/00893Feeding means for the reactants
    • B01J2208/00929Provided with baffles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/32Details relating to packing elements in the form of grids or built-up elements for forming a unit of module inside the apparatus for mass or heat transfer
    • B01J2219/332Details relating to the flow of the phases
    • B01J2219/3322Co-current flow

Definitions

  • the present invention relates to a mixing device for admixing gas or vapor and liquid in a vessel where a vapor phase and a liquid phase are flowing concurrently.
  • the purpose of the device is to equilibrate the temperature and chemical composition of the outlet mixture exiting the device.
  • the invention is suited for but not limited to the application of admixing hot hydrogen rich treatgas and hot hydrocarbon liquid with a cold quench stream between two adjacent beds of catalyst in a hydroprocessing reactor like a hydrotreating or hydrocracking reactor.
  • the invention furthermore relates to a catalytic reactor comprising a mixing device mentioned above, a method of admixing vapor and liquid in a concurrent flow thereof and a product produced by said method.
  • Type 1 Vortex mixers with inlet chutes provided in a collection tray:
  • the mixer consist of a horizontal collection tray plate 6.
  • the collection tray plate is provided with a plurality of sloped chutes 32/34.
  • the entire process stream of vapor and liquid from the catalyst bed above passes through these inlet chutes at high velocity.
  • Below the collection tray is an annular mixing box 8.
  • the exit jets from the chutes have horizontal components and are resulting in a swirling fluid motion inside the annular mixing box.
  • the fluids are then passing over an internal weir 12 and then vertically downward through a center opening 10.
  • the cold quench fluid is added through perforated distributor pipes in a spider arrangement 30.
  • a distribution tray 14 is located for rough distribution of the liquid. Tray 14 also serves as impingement plate for the high velocity fluids exiting opening 10.
  • Below the rough distribution tray a distribution tray 4 is located for final distribution of the liquid.
  • Type 2 Swirl box mixers with radial/horizontal inlet flow: An example of such a design is given in US patent 3,353,924.
  • the mixer consists of a collection plate 6.
  • the cold quench media is added through a perforated pipe ring 11 above the collection plate.
  • the vapor and liquid from the catalyst bed 3 above the mixer and the quench fluid are entering the swirl box 7 through a plurality of inlet ports 8.
  • the inlet ports are provided with vanes 9 which introduces a swirling motion to the fluids inside the swirl box 7.
  • Below the center opening a perforated impingement plate 14 is provided with vertical baffles 16.
  • the mixer consist of a collection plate 16 and a cap 18 & 19 overlaying a downcomer 17.
  • the cap and downcomer defines the first mixing swirl chamber.
  • the sidewalls of the cap 19 are provided with angled openings. As the vapor and liquid enters the first swirl chamber through the angled openings a swirling motion is introduced. The fluids are flowing first upwards and over the upper edge of downcomer 17 and then downwards through the downcomer and central opening in plate 16.
  • the present mixer is also provided with a second swirl chamber located below the first swirl chamber with inward radial flow.
  • bubble cap like mixers are given here:
  • the mixer consists of a collection plate 1125, which holds a certain liquid level.
  • the collection plate is provided with vertical baffles 1130 which promotes a swirling motion of the liquid on the plate 1125.
  • the swirling motion is further intensified by quench fluid jets exiting from pipes 1140.
  • a bubble cap like mixer consisting of a slotted cylindrical cap 1150 overlaying a cylindrical downcomer 1165 is mounted over a central opening in plate 1125.
  • the annular space between the cap and the downcomer is provided with semi spiral shaped baffles 1155. The vapor is entering the annular space through the slots in the cylindrical wall of cap 1150.
  • Type 4 Mixers with separate mixing of vapor and liquid
  • the mixer consist of a collection plate 20 with a center opening 30. Above the center opening a vapor swirl box 100/55 for mixing the vapors is located. The vapor swirl box is provided with apertures 95 and swirling means 105. The collection plate 20 is provided with other openings 40 for liquid flow. The openings are connected with channels 65 to direct the liquid towards the centerline of the reactor. During normal operation the collection plate 20 holds a certain liquid level and the vapor enters the vapor swirl box mixer 100/55 and exits through the center opening 30 while the liquid is bypassing the swirl box mixer through the parallel liquid passages 40/65. Below the mixer a rough distributor/impingement plate 90 is located below the mixer.
  • Type 5 Baffled box mixer with vertical flow
  • the mixer consists of an inlet feed conduct 12 where the vapor and liquid enters the mixer. From the inlet feed conduct the fluids are passed through two circular mixing orifices formed by doughnut plates 32 & 36 and through one annular flow restriction formed by the disc 34.
  • Type 6 Baffled box mixer with horizontal flow
  • the mixer is build as an integral part of the catalyst support system. Vapor and liquid is collected in the annular collecting trough 24. Quench fluid is added to the annular collection trough through quench pipes 22 and 23. The vapor and liquid is flowing through the annular collection trough to the mixer box 30 located between the support beams 14 & 15. The entire process stream is entering the mixer box at the inlet 36.
  • the mixer box consists of a single flow channel with 360° turn in flow direction. After the 360° turn in the mixer box the fluid exits through the center opening 37.
  • US patent 3,705,016 describes a mixer consisting of a screen 11/12 located on a collection and catalyst support plate 8. The screen is covered by inert support material 7. Quench fluid is injected in the catalyst bed above plate 8. The vapor and liquid can pass through the screen 11/12 while the inert material cannot. After having passed through the screen the vapor and liquid is flowing vertically through the center opening in collection plate 8. Below the collection plate a horizontal mixing box consisting of horizontal bottom plate 16 and vertical baffles 20, 21 , 22 and 23 is located below the collection plate 8. The fluids exiting the center opening are first divided into two horizontal streams. Then each of the two streams is again divided into two streams resulting in a total of four streams.
  • the mixer needs to have flow restrictions or mixing orifices with a high flow velocity.
  • the high velocity will disperse the liquid into the vapor or the vapor into the liquid.
  • the dispersed flow results in a large interphase area available for heat and mass transfer.
  • the high velocity also results in a high degree of turbulence, which again results in good mixing.
  • the high velocity further results in high mass transfer and heat transfer coefficients for heat and mass transfer between the liquid and vapor phases.
  • the mixer shall have areas with lower flow velocity downstream the mixing orifices to allow for some hold-up time for the vapor and liquid and to create turbulent flow conditions in the transition from high flow velocity to lower flow velocity. Hold-up time is needed for heat and mass transfer. Turbulent flow conditions are needed to mix the phases.
  • the mixer shall be as compact as possible to reduce the height requirement of the reactor/vessel.
  • a hydrotreating or hydrocracking reactor the room taken up by the mixer cannot be utilized for the active catalyst. A given total volume of catalyst is required in order to convert the reactants into the desired products. Therefore the space occupied by the mixer adds to the required reactor size/height.
  • Hydrocracking reactors are designed for operation up to 200 bar and 450°C with high partial pressures of both hydrogen and hydrogensulfide. Typically the reactors are designed with internal diameters up to 5 meter. Due to the severe design conditions the hydrocracking reactor has a thick shell which is typically constructed of 2.25 Cr 1.0 Mo steel with internal lining of austenitic stainless steel such as 347 SS. The cost of one meter of reactor straight side may be as high as one million US dollar (year 2002). Therefore there is a large potential saving if more compact mixer designs are utilized.
  • the type 1 mixers the vortex mixers with inlet chutes, are the most commonly used mixer designs in commercial hydrotreating and hydrocracking applications today.
  • the major part of the mixer pressure drop is used in the inlet chutes.
  • these chutes represent parallel flow paths. Therefore criterion B is not fulfilled.
  • the distribution of vapor and liquid to each inlet chute may be poor due to an unleveled collection plate or due to other fabrication tolerances.
  • Some chutes may pass a major fraction of the liquid while other chutes are passing the major fraction of the vapor. In such a case the vapor and liquid is not contacted efficiently in the inlet chutes.
  • the holdup time in the annular box is normally insufficient to allow for one full rotation, 360 degrees, of the fluids, so the fluids from different chutes, different sides of the reactor, are never mixed thoroughly.
  • the flow velocity in the inlet chutes is normally too high to allow for liquid separation in the annular box as originally claimed.
  • the entire process stream is contacted in the center opening of the mixer, however the fluids spread all over the reactor cross section immediately after. There is no confined volume to allow for hold up time for heat and mass transfer downstream the center opening. Therefore criterion C is not fulfilled either.
  • the type 1 mixers are relatively compact mixers.
  • the Swirl box mixers with radial/horizontal inlet flow the inlet to the swirl chamber takes up a major part of the pressure drop. Again these inlets represent parallel flow paths. Therefore criterion B is not fulfilled.
  • the entire process stream is contacted in the center opening. However the fluids spreads all over the reactor cross section immediately after. There is no confined volume to allow for hold up time for heat and mass transfer downstream the center opening. Therefore criterion C is not fulfilled either.
  • mixers with separate mixing of vapor and liquid part of the mixer pressure drop is used in premixers to premix the vapor and liquid separately and in parallel.
  • Each single phase premixer in itself also consist of parallel flow paths like parallel inlet chutes or vanes.
  • the mixers do therefore not fulfill criteria B.
  • European patent 716,881 no two-phase mixing orifice is present at all, so criteria A is not fulfilled here either.
  • baffled box mixer with vertical flow US Pat. No. 4,223,269 represents an excellent design regarding mixing performance and fulfills all the criteria A through D given above.
  • the type 5 mixers results in very large mixer heights and does thus take up a significant volume of the reactor/vessel.
  • the type 6 mixers, baffled box mixer with horizontal flow, US patent 3,705,016 and US patent 3,977,834 represent mixer designs with more parallel fluid paths and do thus not fulfill criterion B.
  • US patent 3,977,834 do not fulfill criterion A either since the entire process stream is never contacted in one mixing orifice.
  • US patent 3,705,016 do not fulfill criteria D since the liquid exits the mixer in an uneven pattern.
  • the type 6 mixer, US patent 5,690,896, is a reasonable good mixer.
  • the mixer does not fulfill criteria C. After having brought the entire process stream together in the mixing orifice there is not sufficient hold up time downstream of the orifice for heat and mass transfer. Also criteria D is not fulfilled since the fluids approaches the center orifice from one side only. The resulting liquid spread at the mixer exit is uneven.
  • the invention is a mixing device for admixing gas or vapor and liquid in a vessel with concurrently flow of vapor and liquid.
  • the invention belongs to the mixer type 6, baffled box mixer with horizontal flow, as defined above.
  • One of the main objects of the invention is to provide for such mixing with a relatively small loss of reactor volume and with relatively low energy requirements.
  • this and other object and advantages are obtained by providing a mixing device for use in a catalytic reactor and arranged between an upper catalyst bed and a lower catalyst bed thereof for admixing gas or vapor and liquid flowing concurrently inside the vessel of said reactor through said mutually superimposed catalyst beds, said mixing device being adapted for defining a flow path through said mixing device for said vapor and liquid flowing from said upper catalyst bed to said lower catalyst bed or vice versa, said flow path comprising: at least one inlet aperture of said mixing device, - at least one outlet aperture of said mixing device, a first and at least one second mixing orifice or passage arranged sequentially along said flow path, said first and said at least one second mixing orifice being arranged and adapted such that substantially the entire combined flow of liquid and vapor is constrained to flow through each of said mixing orifices having such a flow-through area relative to the flow rate of said combined flow that the no-slip two-phase flow velocity of said combined flow in the mixing orifice is between 3 m/s and 15
  • the invention provides for a mixing device for use in a catalytic reactor and arranged between an upper catalyst bed and a lower catalyst bed thereof for admixing gas or vapor and liquid flowing concurrently inside the substantially vertical vessel of said reactor through said mutually superimposed catalyst beds, said mixing device being adapted for defining a flow path through said mixing device for said vapor and liquid flowing from said upper catalyst bed to said lower catalyst bed or vice versa, said mixing device comprising: a top wall provided with at least one inlet aperture, a bottom wall provided with at least one outlet aperture, a lateral wall extending between the periphery of said top wall and the periphery of said bottom wall for defining an enclosed space between said top and bottom walls, interior partition walls extending between said top and bottom walls adapted for defining said flow path together with said top and bottom walls, said partition walls furthermore being adapted for defining a first and at least one second mixing orifice or passage arranged sequentially along said flow path, said first and said at least one second mixing orifice being arranged and adapted such that
  • the invention in one embodiment, is a flow-obstructing horizontal mixing box located between the walls of a cylindrical reactor.
  • the mixing box has one or more openings for essentially vertical fluid flow into the mixer.
  • the mixing box comprises a horizontal circular top wall, a horizontal circular bottom wall and a vertical cylindrical wall, which may be a section of the inner wall of the reactor.
  • the diameter of the mixing box is preferably close to or identical to the inner diameter of the reactor.
  • vertical flow baffles are provided inside the horizontal mixing box.
  • the vertical flow baffles form mixing orifices where the entire process stream is flowing through at high flow velocity.
  • the mixing orifice is followed by a "tee", dividing the process stream into two side streams with lower flow velocity.
  • the horizontal mixing box consist of a series of these mixing orifices followed by tee's meaning that the fluids are first combined at high flow velocity in a first flow restriction then split into two streams of lower velocity by a first tee, then recombined at high velocity in a second flow restriction etc.
  • the liquid is dispersed in the vapor to provide a large interphase area for heat and mass transfer.
  • the high flow velocity in the mixing orifices also results in high heat and mass transfer coefficients and in turbulent conditions, which provides mixing. Criterion A is therefore fulfilled. Since the entire process stream is passed through each mixing orifice Criterion B is also fulfilled.
  • Criterion C is therefore also fulfilled.
  • the fluids After having passed through the series of mixing orifices and tee's the fluids exit in a vertical direction through one or more openings in the circular horizontal bottom wall.
  • Criterion D is therefore also fulfilled.
  • Below the opening in the circular horizontal bottom wall an impingement plate is located to break down the high velocity of the two-phase jet and to spread the liquid over the cross section of the reactor.
  • Quench fluid may be added upstream the first mixing orifice either above the horizontal top wall or between the horizontal top and bottom walls. Quench fluid may also be added between two mixing orifices. While the existing type 6 mixers do not fulfill all of the criteria for proper mixing performance A through D, the present invention does. Compared to the present art the invention has improved mixing performance in terms of achieving an outlet stream from the mixer which has been equilibrated regarding temperature and composition. Further, unlike most mixers described in the present art, the invention utilizes most of the reactor cross section for the mixing box. The large diameter of the mixing box has helped reducing the height requirement of the invention compared to the present art.
  • the calculated height of the present invention is compared with the calculated height of the vortex mixer of US patent 4,836,989 for twelve commercial hydroprocessing applications. Both mixers have been designed for the same total pressure drop for each of the twelve commercial applications. As seen the height reduction achievable if the present invention is applied instead of the vortex mixer is 35 mm to 440 mm or 15% to 55%. This is the achievable height reduction of the mixer itself.
  • the quench fluid distributor may be build as an integral part of the present invention, while a separate quench distributor located above the mixer is required for the vortex mixer. See US pat. no. 4,836,989. The separate quench fluid distributor takes up some additional height.
  • Graph 1 The height of the present invention compared to the height of the vortex mixer (US pat, no. 4.836.989..
  • Figure 1 is a schematic sketch showing a typical layout of catalyst and internals in a hydroprocessing reactor with two beds of solid catalyst particles. Figure 1 is also showing the typical location of the mixing device between two adjacent catalyst beds inside the reactor.
  • Figure 2 is a schematic perspective isometric cut-away view of one embodiment of the mixing device according to the present invention.
  • Figure 3A is an overhead view of the embodiment of the mixing device from figure 2.
  • Figure 3B is a side sectional view taken along the segment A-A of figure 3A.
  • Figure 3C is a side sectional view taken along the segment B-B of figure 3A.
  • Figure 4A, 5A, 6A, 7A, 8A, 9A and 10A are overhead views of alternative embodiments of the present invention.
  • Figure 4B, 5B, 6B, 7B, 8B, 9B and 10B are the corresponding side sectional views taken along the segments A-A.
  • Figure 4C, 5C, 6C, 7C, 8C, 9C and 10C are the corresponding side sectional views taken along the segments B-B.
  • Figure 7D is the side sectional view taken along the segment C-C in figure 7A.
  • hydroprocessing reactors The reactions taking place in hydroprocessing reactors are exothermic. Heat is therefore released during reaction and is causing the temperature to rise when the reactants are converted to products in presence of a hydroprocessing catalyst at elevated temperature and pressure.
  • the two-phase mixture of reactants is flowing trough a bed of solid catalyst particles.
  • the ideal flow pattern in such a reactor is plug flow where liquid is flowing downwards with the same velocity (based on empty reactor) at all points of the reactor cross-section.
  • the ideal plug flow case the same is true for the vapor phase: The vapor is flowing downwards with identical velocity (based on empty reactor) at all points of the reactor cross-section.
  • a first example is a diesel hydrotreating reactor where sulfur containing hydrocarbon components and H 2 is converted to sulfur free hydrocarbon components and H 2 S. If non-uniform temperatures exist, then a fraction of the feed oil is reacted at higher temperature and maybe also at lower space velocity due to lower liquid velocity as discussed above. Another fraction of the feed oil is reacted at lower temperature and maybe also higher space velocity due to higher liquid velocity. The result is that the organic sulfur tends to "by-pass" the catalyst bed through the areas with low temperature and high space velocity.
  • This by-pass significantly increases the content of organic sulfur in the overall product.
  • the refiner needs to reduce the feed rate or increase the reactor operating temperature to compensate for the non-uniform temperatures and composition. Reducing the feed rate has a significant cost in terms of lost production.
  • Increasing the reactor temperature results in increased energy consumption and reduced run length with increased frequency of shutdowns for catalyst generation/replacement. The increased frequency of shutdowns has significant costs as discussed above.
  • a second example is a hydrocracking reactor where heavier hydrocarbon components and H 2 are converted to lighter hydrocarbon components. Again if non-uniform temperatures exist then a fraction of the feed oil is reacted at higher temperature and maybe also at lower space velocity due to lower liquid velocity. Another fraction of the feed oil is reacted at lower temperature and maybe also higher space velocity due to higher liquid velocity. The result is that part of the heavy feed oil is "overcracked" so that the production of unwanted
  • Non-uniformities in temperature and chemical composition in the horizontal plane of a catalyst bed are unavoidable in commercial hydroprocessing reactors. However the non-uniformities can be minimized by installing suitable reactor internals.
  • a good inlet distributor needs to be provided to ensure equal distribution of the liquid and vapor over the cross section of the reactor.
  • the fluids entering this distributor need to be properly mixed upstream the distributor to ensure that compositional and thermal equilibrium has been achieved. Sufficient mixing of the fluids is most often provided in the piping routing the reactants to the reactor.
  • the inlet stream to a subsequent catalyst bed is the outlet stream from an upstream catalyst bed where a non-uniform temperature and chemical composition will exist at the bed outlet. Therefore it is essential to have a mixing device located between the upstream catalyst bed and the distributor. Otherwise the non-uniformity in temperature and chemical composition may proceed from one bed to the next and worsen.
  • the purpose of the mixing device is to produce an outlet stream, which is equilibrated regarding temperature and composition.
  • a quench fluid which is colder than the fluids inside the reactor, is often injected into the hydroprocessing reactor between two adjacent catalyst beds in order to cool down the hot effluent from one catalyst bed before the fluids enter the next bed. This allows for operation of the reactor closer to isothermal conditions, which has several benefits in terms of increased run length and improved product quality.
  • a further objective of the mixing device in this case is to mix the cold quench stream with the effluent from one catalyst bed to achieve thermal and compositional equilibrium before the stream enters the next catalyst bed.
  • Figure 1 shows a sketch of a typical hydroprocessing reactor 1 with two beds of catalyst particles 2 and 3.
  • Figure 1 is intended to define the typical location of the mixing device relative to the catalyst beds and to other reactor internals.
  • the reactants enter the reactor through an inlet nozzle 4.
  • the fluids now enter the top distribution tray 5, which distributes the vapor and liquid evenly over the cross section of the reactor before the fluids enter catalyst bed 2.
  • Catalyst bed 2 is resting on a screen or catalyst support grid 6. Large forces are normally acting on the catalyst screen or support grid due to the large weight of the catalyst and due to the forces introduced by the fluid flow through the catalyst bed. Therefore support beams 7 are normally required to absorb these forces.
  • Below the catalyst support system 6 & 7 the mixing device 8 is located below the catalyst support system 6 & 7 .
  • Quench fluid may be added through a quench nozzle 9.
  • an impingement device 10 for spreading the liquid and for breaking down the high velocity of the jet exiting the mixing device, may be located.
  • a second distribution tray 11 is located which distributes the vapor and liquid evenly over the cross section of the reactor before the fluids enter the next catalyst bed 3. The product from the reactor exits through the outlet nozzle 12.
  • the number of mixing devices 8 is typically N-1 where N is the number of catalyst beds in the reactor.
  • FIGS. 2 through 9 represent alternative structures of the mixing device according to the present invention.
  • the figures are presented only to characterize the invention and alternatives. They are not intended to limit the scope of the concepts disclosed herein or to serve as working drawings. They should not be construed as setting limits on the scope of the inventive concept.
  • the relative dimensions shown by the drawings should not be considered equal or proportional to commercial embodiments.
  • FIG. 2 is a schematic perspective isometric cut-away view of a mixing box 8 consisting of a circular top plate 13, a circular bottom plate 14 and a cylindrical side wall 15.
  • the cylindrical side wall 15 may be a section of the inner reactor wall or it may be a separate wall with smaller diameter than the reactor. Preferable the diameter of the cylindrical wall 15 is close to the reactor diameter in order to minimize the height of the mixer.
  • the mixing box form an essential leak tight flow obstruction inside the reactor 1 except from openings 16 in the top plate 13. In the case where the diameter of the cylindrical wall is smaller than the inner diameter of the reactor a tray plate or other means will have to be used to ensure an essential leak tight seal between the mixing box 8 and the inner walls of reactor 1.
  • Quench fluid is injected into the mixing box 8 through a perforated quench distributor 17.
  • Flow baffles 18, 19 and 20 are installed inside the mixing box to form a series of mixing orifices 21 & 22 with high velocity and combined flow and flow channels 23 & 24 with lower velocity and divided flow.
  • the flow baffles form an essential leak tight installation except from the openings 21 , 22 and 24 and are thus forcing fluid to flow through these openings only.
  • a circular outlet opening 25 concentric with the reactor centerline is provided in the bottom plate 14. This circular opening serves as the third and final mixing orifice in the mixer.
  • Figure 3A is an overhead view of the mixer from figure 2.
  • Figure 3B is a sectional view along segment A-A of figure 3A.
  • Figure 3C is a sectional view along segment B-B of figure 3A.
  • Figure 3A and 3B is showing the circular impingement plate 26 which is concentric with and located below the circular opening 25.
  • the intended flow through the device is indicated with arrows on figure 3A, 3B and 3C.
  • the vapor and liquid exiting the catalyst bed 2 will flow through the openings 16 and into the mixing box.
  • Cold quench fluid is added through distributor 17.
  • the entire process stream is now passed through the mixing orifice 21 where the flow velocity is high and where the liquid is dispersed into the vapor.
  • the stream is divided into two streams with lower velocity by the flow baffle 19.
  • the two streams now flow in the two symmetrical channels 23 to the next mixing orifice 22 where the stream is again recombined at high flow velocity.
  • the stream is again divided into two streams with lower velocity by flow baffle 20 and the two streams now flow through the two symmetric openings/channels 24 to the center opening 25 where the stream is recombined at high flow velocity in this third and last mixing orifice.
  • the impingement plate 26 will ensure that the fluids exit the mixer in an outwards radial direction.
  • the impingement plate prevents the mixer from sending a high velocity jet directly towards the distributor tray 11. Such a jet may disturb the liquid level on the distribution tray and it may entrain the liquid.
  • the impingement plate 26 will further ensure a good spread of the liquid across the cross section of the reactor before the fluids enters the distribution tray 11.
  • the flow baffles in the mixing box can have many different shapes. They can be straight, curved, angled etc. also the baffles do not need to be strictly vertical it is sufficient that the baffles have a vertical component.
  • the inlet and outlet openings 16 and 25 may also have different shapes such as semi segmental as shown in figure 2 and 3, ellipsoidal, circular, rectangular, triangular etc. The number of inlet openings and outlet openings respectively, may vary from one and upwards.
  • the cross section of the mixing box itself can have any shape. It can be a circle as for the mixer in figure 2, 3A, 3B and 3C, it can also be a triangle, rectangle or polygon. A circle or a polygon with many sides are preferred since the mixing box in this case can be designed with a cross sectional area which is close to the inside cross sectional area of the vessel.
  • FIG. 4A is an overhead view of an alternative mixing box 8.
  • Figure 4B is a sectional view along segment A-A in figure 4A.
  • Figure 4C is a sectional view along segment B-B in figure 4A.
  • the mixing box consist of a top wall 13 and a bottom wall 14 ' both with the shape of a polygon with eight sides and side wall 15 ' .
  • the top wall is provided with two circular openings 16 ' for fluid flow to the mixing box 8. Quench fluid is added downstream the openings 16 ' and between the top and bottom plates 13 and 14 through a perforated quench fluid distributor 17.
  • Flow baffle 19 ' is located in the mixing box to first divide the stream from mixing orifice 21 into two channels 23 ' and later to recombine the two streams into one stream in a second mixing orifice 22 ' .
  • the corners of flow baffle 19 close to mixing orifice 21 are curved while the corners of flow baffle 19 close to mixing orifice 22 ' are angled.
  • Downstream mixing orifice 22 ' an angled flow baffle 20 ' is located.
  • Flow baffle 20 ' is dividing the stream from the second mixing orifice 22 into two flow channels 24 ' before the entire stream is recombined in a third and last mixing orifice which is a square outlet opening 25 ' . Below outlet opening 25 an impingement plate 26 is located.
  • the mixers on figure 2, 3A, 3B, 3C, 4A, 4B and 4C have three mixing orifices 21 , 22 and 25 (or 21 , 22 and 25). However the mixing device can be constructed with two or more mixing orifices.
  • Figure 5A, 5B and 5C represents an example of a mixing box 8 with four mixing orifices. The flow path through the mixer is indicated by arrows.
  • Figure 5A is an overhead view of the mixing box 8.
  • Figure 5B is a sectional view along segment A-A in figure 5A.
  • Figure 5C is a sectional view along segment B-B in figure 5A.
  • the mixing box consist of a circular top wall 13 " , a circular bottom wall 14 and a cylindrical side wall 15 " .
  • the top wall is provided with one rectangular opening 16 " , which serves as passageway for fluid flow to the mixing box 8 and as a first mixing orifice. Quench fluid is not added in the mixing box 8 but may be added upstream the mixing orifice 16 " .
  • flow baffle 27 " is located to divide the stream from mixing orifice 16 " into two flow channels 28 " .
  • Flow baffles 18 are located in the mixing box to form a second mixing orifice 21 where the entire process stream is recombined.
  • Flow baffle 19 is located in the mixing box to first divide the stream from mixing orifice 21 into two channels 23 " and later to recombine the two streams into one stream in a third mixing orifice 22 .
  • Downstream mixing orifice 22 " a flow baffle 20 " is located.
  • Flow baffle 20 " is dividing the stream from the third mixing orifice 22 into two flow channels 24 " before the entire stream is recombined in a fourth and last circular mixing orifice 25 .
  • Below mixing orifice 25 a circular impingement plate 26 " is located.
  • Figure 6A, 6B and 6C represent an example of a mixing box 8 with two off-center outlet openings 25 " .
  • the flow path through the mixer is indicated by arrows.
  • Figure 6A is an overhead view of the mixing box 8.
  • Figure 6B is a sectional view along segment A-A in figure 6A.
  • Figure 6C is a sectional view along segment B-B in figure 6A.
  • the mixing box consist of a circular top wall 13 " , a circular bottom wall 14 " and a cylindrical side wall 15 " .
  • the top wall is provided with one circular opening 16 " , which serves as passageway for fluid flow to the mixing box 8 and as a first mixing orifice. Quench fluid is added downstream the first mixing orifice 16 through the perforated quench fluid distributor 17 " located between the top wall 13 and the bottom wall 14 " .
  • flow baffle 27 is located to divide the stream from mixing orifice 16 into two flow channels 28 '" .
  • Flow baffles 18 are located in the mixing box to form a second mixing orifice 21 " where the entire process stream is recombined.
  • Flow baffle 20 is located in the mixing box to divide the stream from mixing orifice 21 into two channels 24 '" .
  • Flow baffle 19 " is located in the mixing box to form a third mixing orifice 22 " where the stream flowing in channels 24 are recombined.
  • the flow direction through mixing orifice 22 " is the reverse of the flow direction through mixing orifices 22, 22 ' and 22 " on figure 2, 3A, 4A and 5A.
  • the entire process stream exiting the third mixing orifice 22 is divided into two channels 23 leading to the outlet openings 25 " .
  • An optional divider baffle 29 may be used to obtain a more uniform split of the liquid to each of the channels 23 for improved liquid distribution to the distribution tray 11.
  • the streams exit the mixing box through the two rectangular openings 25 " . Below each outlet opening 25 an impingement plate 26 is located.
  • the mixer has the disadvantage compared to the previous examples that poor distribution or poor spread of the liquid to the distribution tray 11 may occur. This is because the fluid approaches each outlet opening 25 "' only from one side, because the outlet openings are not located in the center of the reactor and because the liquid flow rate through each of the openings 25 " may differ due to uneven split of the liquid at the exit of mixing orifice 22 " .
  • the mixing device can be constructed with two or more mixing orifices.
  • Figure 7A, 7B, 7C and 7D represents an example of a mixing box 8 with two mixing orifices 21 * and 22 * .
  • Figure 7A is an overhead view of the mixing box 8.
  • Figure 7B is a sectional view along segment A-A in figure 7A.
  • Figure 7C is a sectional view along segment B-B in figure 7A.
  • Figure 7D is a sectional view along segment C-C in figure 7A.
  • the flow path through the mixer is indicated by arrows.
  • the mixing box consist of a circular top wall 13 * , a circular bottom wall 14 * and a cylindrical side wall 15 * .
  • the top wall 13 * is provided with two circular inlet openings 16 * , which serves as passageway for vapor and liquid flow to the mixing box 8.
  • a cylinder 30 * which is open in both the upper and lower ends is mounted over or through each of the inlet openings 16 * to form an essentially leak free joint between the top wall 13 * and cylinder 30 * .
  • the upper rims of the cylinders are provided with V-notches. During operation the top wall 13 * will hold a certain liquid level and due to the V-notches the liquid flow to the inlet openings 16 * will be stable in time. Fluctuations in liquid inlet flow rate to the mixer are thus avoided.
  • the cylinders 30 * with V-notches serves for liquid distribution to each inlet opening 16 * so that the liquid flow rate to each of the inlet openings will be close to identical.
  • the channels 30 * are shown as cylinders but could have any other cross section such as ellipsoidal, rectangular, triangular or polygonal.
  • the upper rim of cylinders 30 * are shown to be provided with V-notches but other shapes of the openings for liquid flow in the cylinder 30 * could be used such as slots or circular holes.
  • Quench fluid is not added inside the mixing box 8 but may be added upstream the circular inlet openings 16 * , not shown.
  • Inside the mixing box two flow baffles 18 * are located to form a first mixing orifice 21 * where the entire process stream is flowing through.
  • Flow baffle 20 * is located in the mixing box to divide the stream from mixing orifice 21 * into the two flow channels 24 * .
  • Flow baffle 19 * is located in the mixing box to form a second mixing orifice 22 * wherein the stream flowing in channels 24 * are recombined.
  • the entire process stream exiting the second mixing orifice 22 * is divided into two channels 23 * each leading to a rectangular outlet opening 25 * .
  • An optional divider baffle 29 * may be used to obtain a more uniform split of the liquid to each of the two flow channels 23 * for improved liquid distribution to the distribution tray 11.
  • the streams exit the mixing box through the two rectangular outlet openings 25 * . Below each outlet opening 25 * an impingement plate 26 * is located below each outlet opening 25 *.
  • the present mixer has the disadvantage that poor distribution or poor spread of the liquid to the distribution tray 11 may occur. This is because the fluid approaches each outlet opening 25 * only from one side, because the outlet openings are not located in the center of the reactor and because the liquid flow rate through each of the openings 25 * may differ due to uneven split of the liquid at the exit of the second mixing orifice 22 * .
  • a disadvantage of the present mixer compared to the previous examples is a slightly reduced mixing performance since there are only two mixing orifices instead of three or more.
  • the mixer also has some advantages: Since the mixer only has two mixing orifices the flow velocity through the mixer can be higher for a given pressure drop than for mixers with three or more mixing orifices.
  • the cross section of the mixing orifices and the flow channels in the mixer can therefore be smaller. Smaller required cross sectional area of the mixing orifices and the flow channels result in a mixer with lower height than mixers designed with three or more mixing orifices. Also the design with the two off-center outlet openings 25 * and with identical flow direction through mixing orifices 21 * and 22 * helps reducing the mixer height further.
  • the mixer thus represents a very compact design with low height, which may be utilized in small diameter reactors with little room available for the mixing device. For small diameter reactors the liquid distribution or spread to the distribution tray is less critical since the level gradients introduced on the distribution tray 11 in case of poor liquid spread from the mixer is not as significant as for large diameter reactors.
  • FIG. 8A, 8B and 8C represent an example of a mixing box 8 with two mixing orifices 16 ** and 22 ** where both mixing orifices has a circular cross section.
  • Figure 8A is an overhead view of the mixing box 8.
  • Figure 8B is a sectional view along segment A-A in figure 8A.
  • Figure 8C is a sectional view along segment B-B in figure 8A. The flow path through the mixer is indicated by arrows.
  • the mixing box consist of a circular top wall 13 ** , a circular bottom wall 14 ** and a cylindrical side wall 15 ** .
  • the top wall 13 ** is provided with one circular inlet opening 16 ** , which serves as the first mixing orifice and as passageway for fluid flow to the mixing box 8. Quench fluid is not added inside the mixing box 8 but may be added upstream the circular inlet opening 16 ** , not shown.
  • a flow baffle 27 ** is located inside the mixing box 8 but may be added upstream the circular inlet opening 16 ** , not shown.
  • Another flow baffle 19 ** is located in the mixing box to form a second mixing orifice 22 ** wherein the two streams flowing in channels 28 ** are recombined.
  • the entire process stream exiting the second mixing orifice 22 ** is divided into two channels 23 ** each leading to a square outlet opening 25 ** .
  • An optional divider baffle 29 ** may be used to obtain a more uniform split of the liquid to each of the two flow channels 23 * for improved liquid distribution to the distribution tray 11.
  • the streams exit the mixing box through the two rectangular outlet openings 25 ** .
  • the present mixer has the disadvantage that poor distribution or poor spread of the liquid to the distribution tray 11 may occur and the disadvantage of slightly reduced mixing performance compared to the mixer designs with three or more mixing orifices.
  • the present mixer represents a very compact design with low height, which may be utilized in small diameter reactors with little room available for the mixing device.
  • Figures 9A, 9B and 9C represents an example of a mixing box with three mixing orifices similar to the mixer from figures 2, 3A, 3B and 3C. However the inlet opening 16 *** , the flow baffles 19 *** and 20 *** and the quench distributor 17 *** have been modified. The flow path through the mixer is indicated by arrows.
  • Figure 9A is an overhead view of mixing box 8.
  • Figure 9B is a sectional view along segment A-A in figure 9A.
  • Figure 9C is a sectional view along segment B-B in figure 9A.
  • the mixing box consist of a circular top wall 13 *** , a circular bottom wall 14 *** and a cylindrical side wall 15 *** .
  • the top wall is provided with a segmental cut away which is forming the inlet opening 16 *** for fluid entrance to the mixing box 8.
  • Quench fluid is added downstream the inlet opening 16 *** through a quench fluid distributor 17 *** located between the top and bottom plates 13 *** and 14 *** .
  • the quench fluid distributor can be of different types and the quench fluid exit direction from the distributor can have any direction. In this case a perforated "Tee" distributor with the fluid jets pointing downwards are shown.
  • two flow baffles 18 *** are located forming a first mixing orifice 21 *** where the entire process stream is flowing through at high flow velocity.
  • a curved flow baffle 19 is located in the mixing box to first divide the stream from mixing orifice 21 *** into two channels 23 *** and later to recombine the two streams into one stream in a second mixing orifice 22 *** .
  • Downstream mixing orifice 22 *** a stepped flow baffle 20 *** is located.
  • Flow baffle 20 *** is dividing the stream from the second mixing orifice 22 *** into two flow channels 24 *** before the entire stream is recombined in a third and last circular mixing orifice and outlet opening 25 *** .
  • the mixing box 8 is preferably orientated so that the flow direction through the mixing orifice with horizontal flow, such as mixing orifice 21 on figure 2, is parallel to any support beams 7 extending below the surface of the catalyst screen or support grid 6. This is in order to minimize the pressure drop for fluid flow from the outlet of catalyst bed 2 to the inlet opening to the mixing box 16. Any significant pressure drop in this area is unwanted since it will result in an uneven flow pattern through the catalyst bed 2.
  • the inlet opening(s) 16 of the previous mixer examples are all located close to the side wall 15 of the mixer. This location of the inlet openings tends to increase the above mentioned pressure drop for vapor and liquid flowing from the outlet of the upstream catalyst bed 2 to the inlet opening(s) 16 of the mixer. In order to reduce this pressure drop the inlet opening(s) may be located closer to the reactor centeriine.
  • Figure 10A, 10B and 10C represent an example of a mixing box 8 with a segmental inlet opening 16 x located closer to the center of the mixer and closer to the center of the reactor.
  • Figure 10A is an overhead view of the mixing box 8.
  • Figure 10B is a sectional view along segment A-A in figure 10A.
  • Figure 10C is a sectional view along segment B-B in figure 10A.
  • the flow path through the mixer is indicated by arrows.
  • the mixer has two mixing orifices.
  • the mixing box consist of a circular top wall 13 x , a circular bottom wall 14 x and a cylindrical side wall 15 x .
  • the top wall 13 x is provided with the segmental inlet opening 16 x which serves as passageway for fluid flow to the mixing box 8. Quench fluid is not added inside the mixing box 8 but may be added upstream the segmental inlet opening 16 x , not shown.
  • Two semicircular flow baffles 18 x are located to form the first mixing orifice 21 x and the second mixing orifice 22 x .
  • the entire process stream flowing through inlet opening 16 x is entering the first mixing orifice 21 x .
  • the process stream exiting the first mixing orifice 21 ** is divided into two channels 23 x .
  • the vapor and liquid is flowing along the cylindrical side wall 15 x to the second mixing orifice 22 x where the entire process stream is recombined at high flow velocity.
  • An optional flow baffle 20 x may be used to split the stream exiting the second mixing orifice into two lower velocity streams before the fluids exit the mixer through the square outlet opening 25 x .
  • the flow baffle 20 x may be eliminated and an optional flow baffle 31 x located in the outlet opening 25 x may be used instead.
  • flow baffle 31 x The function of flow baffle 31 x is to prevent that the high velocity stream exiting the second mixing orifice is "shooting" towards one side of the reactor only as the stream is passing through the outlet opening 25 x . The result would be poor liquid spread to the distribution tray below.
  • the outlet opening 25 x and the inlet opening 16 x are not considered as mixing orifices since the flow velocity through these openings is fairly low. Below the outlet opening 25 x an impingement plate 26 x is located below the outlet opening 25 x.
  • the catalyst support system consists of catalyst screen 6 and support beams 7.
  • the catalyst support system and the mixing device 8 are shown to be separate structures on figure 1.
  • the mixing device of the present invention may be build as an integral part of the catalyst support system.
  • the mixing box itself may require support beams or other structures to absorb the forces caused by the pressure drop across the mixing box. These support beams or structures are not shown in any of the figures but may be located above or below the mixing box or may be an integral part of the mixing box and flow baffles. For any of the embodiments of the present invention low capacity drain holes may be provided.
  • the plates, which make up the mixer may be in one piece or assembled of several plate sections. Normally several removable sections will be provided in the mixer for easy access during inspection and cleaning procedures and to provide a man way through the mixing box.
  • the two phase no-slip flow velocity in a flow channel or opening is defined as the flow velocity in the case where there is no slip between the liquid and vapor phases, meaning that the velocity of the liquid phase is identical to the velocity of the vapor phase.
  • the no-slip velocity is therefore:
  • Q ⁇ is the volumetric liquid flow rate through the channel or opening
  • Q v is the volumetric vapor flow rate through the channel or opening
  • A is the cross sectional area of the channel or opening.
  • the mixing box 8 is typically close to horizontal meaning that the overall slope of the mixing box from one side of the reactor 1 to another is small.
  • the diameter of the mixing box 8 is typically between 50 and 100% of the inner diameter of the reactor.
  • the cross sectional area of each mixing orifice is selected to obtain a no-slip flow velocity of typically 3-15 m/s.
  • the cross sectional area of the channels with divided flow downstream a mixing orifice is selected to obtain a maximum no-slip flow velocity of typically 0.25 to 1.00 times the flow velocity in the corresponding mixing orifice.
  • the height of the mixer from top plate to impingement plate may vary from 100 mm for small diameter reactors to above 500 mm for large diameter reactors.
  • the horizontal width of the flow baffles 20 and 27 is typically between 1 and 3 times the maximum width of the upstream mixing orifice.
  • a mixing device for admixing vapor and liquid flowing concurrently inside a vertical vessel in which the vapor and liquid is obstructed by an essential horizontal mixing box which forces the vapor and liquid to pass through a plurality of mixing sequences in series.
  • one mixing sequence is defined as one mixing orifice followed by one tee.
  • a mixing orifice is defined as one opening where the combined process stream is flowing through at high velocity and a tee is defined as a stream split from one mixing orifice with high flow velocity into two flow channels with lower flow velocity.
  • the "essential horizontal" mixing box is defined as a mixing box where the overall slope of the mixing box from one side of the vessel to another side is less than 20% corresponding to an angle between the horizontal plane and the mixing box of maximum 11.5 degrees. Separate segments of the mixing box can have higher slopes as long as the overall slope from one side of the vessel to another side of the vessel is less than the 20% corresponding to 11.5 degrees.
  • the cross sectional area of the essentially horizontal mixing box in the plane perpendicular to the vessel walls is between 25% and 100% of the inner cross sectional area of the vessel.
  • the area between the mixing box and the vessel wall is sealed by plate or other means to obtain an essential fluid tight joint between the mixing box and the vessel walls.
  • a cold quench fluid may be added through a pipe or distributor upstream the first mixing orifice or between two mixing orifices to cool down the process stream.
  • the mixing box comprises at least two mixing orifices.
  • the no-slip two-phase flow velocity in the mixing orifice is between 3 m/s and 15 m/s.
  • the maximum no-slip two-phase flow velocity in the channels with divided flow downstream a tee is above 25% of the no-slip two-phase flow velocity in the upstream mixing orifice with combined flow.
  • the minimum no-slip two-phase flow velocity in the channels with divided flow downstream a tee is below 100% of the no-slip two-phase flow velocity in the upstream mixing orifice with combined flow.
  • the reactor vessel could be a vertical hydroprocessing reactor with downwards concurrent flow of vapor and liquid in which hydrocarbons are reacted with hydrogen rich gas in presence of a hydroprocessing catalyst.
  • one of the mixing orifices or passages may be subdivided into two or more adjacent orifices or passages with common walls.
  • the best results both as regards mixing performance as well as anti-fouling properties, is achieved with each mixing orifice or passage not being subdivided in any way.
  • Turbulence creating means such as for instance vanes, baffles, grids and the like may be provided upstream from or in the mixing orifices or passages.
EP03769259A 2002-11-08 2003-11-05 MISCHVORRICHTUNG F R ZWEIPHASEN-PARALLELSTROMBEHûLTER Ceased EP1562697A1 (de)

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DK200201718 2002-11-08
DKPA200201718 2002-11-08
PCT/DK2003/000757 WO2004041426A1 (en) 2002-11-08 2003-11-05 Mixing device for two-phase concurrent vessels

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WO2004041426A1 (en) 2004-05-21
CN1732040A (zh) 2006-02-08
AU2003277837A1 (en) 2004-06-07
JP4741237B2 (ja) 2011-08-03
EA200500791A1 (ru) 2005-12-29
CN100355494C (zh) 2007-12-19
EA007052B1 (ru) 2006-06-30
JP2006505388A (ja) 2006-02-16

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