Patent Description:
A wide variety of processes use co-current flow reactors, where a fluid or fluids flow over a solid bed of particulate materials, to provide for contact between the fluid and solid particles. In a reactor, the solid may comprise a catalytic material on which the fluid reacts to form a product. The fluid can be a liquid, vapor, or mixture of liquid and vapor, and the fluid reacts to form a liquid, vapor, or a mixture of a liquid and vapor. The processes cover a range of processes, including hydrocarbon conversion, gas treatment, and adsorption for separation.

Co-current reactors with fixed beds are constructed such that the reactor allows for the fluid to flow over the catalyst bed. When the fluid is a liquid, or liquid and vapor mixture, the fluid is usually directed to flow downward through the reactor. Multibed reactors are also frequently used, where the reactor beds are stacked over one another within a reactor shell. Typically, they are stacked with some space between the beds.

The interbed spaces are often created to provide for intermediate treatment of the process fluid, such as cooling, heating, mixing and redistribution.

In exothermic catalytic reactions, the control of fluid temperature and distribution is important. The temperature and composition of the fluids from an upper catalyst bed and from outside of reactor should be well mixed before being distributed to the lower catalyst bed. Initial poor temperature and composition distribution at top of a catalyst bed can persist or grow as the process fluids move down the reactor. Hot spots can develop and cause rapid deactivation of the catalyst and shorten the reactor cycle length. The space between catalyst beds is for the injection of a quench gas or liquid and for fluid mixing and distribution. In hydrocarbon processing, the quench gas is often a cool hydrogen/hydrocarbon stream. However, cooling a fluid without controlling the mixing and distribution leads to uneven reactions and uneven temperature distribution in subsequent reactor beds. And complex mixing and distribution systems takes up valuable space in a reactor chamber holding multiple catalyst beds.

Due to constraints in the height of the space between reactor beds, there is a limited amount of space for introducing a quench fluid and mixing the vapor and liquid along with the quench fluid. Particularly, for existing hydroprocessing reactors, the space between catalyst beds is already set, and sometimes it is difficult to install new internals for improving mixing of fluids within the existing interbed space without reducing the height of catalyst beds. Even for new reactors, it is often desired to reduce the overall size of the reactors to reduce capital expenditure and the profile of the reactor in a processing plant. Therefore, it is desirable to provide for good mixing of fluids between adjacent catalyst beds in a relatively short interbed space.

Previous attempts to overcome these limitations have included vortex or turbulent type mixers which generally include providing flow of the fluids together in a manner to affect mixing. An example of a vortex type mixer is described in <CIT>. The cylindrical mixing device <NUM> is positioned on a collecting tray and includes inlets <NUM> and <NUM> and a single outlet <NUM> in the bottom center of the bottom wall. The fluid and liquid enter the device together through inlets <NUM> and <NUM>. These devices are limited in that mixing is affected by the turbulent or swirling flow of fluids together within the device in the same general direction and with vapor atop of liquid.

The design of reactor internals to overcome these limitations can save significantly on the valuable space within a reactor. New reactor internals that improve the utilization of the space within a reactor shell can maximize catalyst loading, and obviate the need for new reactor shell components, as well as prevent the down time for replacing an entire reactor.

<CIT> relates to a device for the collection, mixing and distribution of fluid between reactor catalyst beds. According to various aspects, the device includes a collection tray, a mixing chamber in fluid communication with the collection tray, a rough distribution tray in fluid communication with the mixing chamber, and a fine distribution tray in fluid communication with the rough distribution tray. The mixing chamber includes at least one vapor chimney positioned about the mixing chamber central outlet. <CIT> relates to a chimney tray for a reactor, wherein a gas reactant and a liquid reactant are mixed well in chimneys and which includes a tray having a plurality of through-holes, and a plurality of chimneys perpendicularly inserted into the through-holes of the tray and having one or more outlets penetrating there through and facing each other, wherein each of the plurality of chimneys includes a conical lower end which is formed such that it extends from the lower surface of the tray to make an angle of <NUM>¼ <NUM>° with respect to the direction of the normal line of the tray. <CIT> relates to a heat exchanger device used especially between catalyst beds in a reactor vessel, including a liquid-liquid pre-mixing baffle upstream of a gas-liquid heat exchange section. <CIT> relates to a device providing mixing of quench gas and process fluids in the height constrained interbed space of a catalytic reactor. The quench zone mixing device includes a collection tray (<NUM>) for receiving vapor and liquid, and a spillway (<NUM>) for the downward passage of vapor and liquid into a mixing chamber (<NUM>) below the collection tray (<NUM>). The mixing chamber (<NUM>) is annular in shape and has a central outlet fitted with a weir (<NUM>) allowing liquid to pass over to a distributor tray underneath. A vertical, continuous solid baffle (<NUM>) is attached to the underside of the collection tray (<NUM>), located between the central outlet and the spillway (<NUM>). <CIT> relates to a vertical downflow reactor, including quench nozzle configurations for symmetrical introduction of a quench fluid into a quench zone. In one embodiment, the quench nozzle includes a closed-ended conduit having longitudinal exit ports or slots proximate its closed end. In another embodiment, the conduit terminates in a "tee", the lateral leg of the "tee" being sealed off and the quench fluid exiting from the downwardly extending leg. <CIT> also is directed to an interzone mixing apparatus in vertical communication with the bottom of the quench zone. An inwardly sloping collector tray has an opening concentric with the vertical axis of the reactor vessel for receiving liquid from the quench zone. A mixing device is provided on the upper surface of collector tray in axial alignment with and covering the opening in the collector tray for mixing and contacting liquid and vapor components entering from above the collector tray and conveying the mixed vapor and liquid downwardly through the opening in the collector tray. Flow deflectors are positioned immediately below the collector tray opening for directing liquid flow towards the axial centerline of the reactor. A horizontally disposed collection pan is connected to the collector tray below and axially aligned with the collector tray opening for collecting liquid flowing through the collector tray opening. The collection pan is provided with a radially outwardly flared downwardly extending skirt to disperse the liquid flow from the collector pan toward the reactor walls, onto a perforated tray them onto a distributor tray through which the vapor and liquid may be delivered to the horizontal cross-section of a reactor vessel second catalyst zone in a conventional manner. A vertical spiral weir may be provided on the surface of the tray panel to add residence time to the liquid on the tray and to utilize the collector tray surface for initiating mixing of the liquid. <CIT> relates to a means to provide mixing of gas and fluids in a height constrained interbed space of a catalytic reactor.

According to various aspects, the mixing device and system, and method for using the same, disclosed herein are disposed in the space between beds in a co-current flow vessel. For ease of explanation the following will be described in terms of a downflow reactor including two or more spaced catalyst beds. The catalyst beds in a reactor are separated by space for quench, mixing and distribution of the fluids, where the mixing zones are designed to cool/heat, mix, and sometimes condense effluent fluids from a catalyst bed above. In one example, as illustrated in <FIG>, the mixing device and system are included in a hydroprocessing downflow reactor <NUM> and fluid flows from superior catalyst bed <NUM> to an inferior catalyst bed <NUM>. The fluid may include vapor, liquid, or a mixture of vapor and liquid. The reactor fluid may be quenched with a quench gas or liquid (collectively referred to as "quench fluid" herein) from a quench fluid distributor <NUM>, and the fluid is mixed and then distributed to the inferior catalyst bed <NUM> in quench zone <NUM>. It should be noted that the term "fluid" as used herein refers to either or both of liquid and vapor. The fluid is mixed to minimize temperature and composition differences before being distributed to the inferior catalyst bed <NUM> below the quench zone. In current systems, there is considerable space between the reactor beds for quench and mixing. A reduction in the amount of space needed for these functions can advantageously provide for maximum catalyst loading within the reactor <NUM> to improve processing and performance without replacing an entire reactor. Similarly, new reactors may be designed with smaller profiles and at smaller capital expense if the height of quench zones is minimized.

Good distribution of liquids over catalyst beds is important to avoid adverse effects, such as uneven temperature rise and hot spots within the catalyst bed. Hot spots occurring in the catalyst beds can lead to a shortened catalyst life or to poor product quality. The methods and devices described herein are designed to reduce the height of quench zone without sacrificing fluid mixing and distribution performance.

By one aspect, a system <NUM> is provided for vapor-liquid contacting in a quench zone between catalyst beds in co-current flow reactor <NUM>. In one example, the reactor <NUM> may be a generally cylindrically shaped downflow reactor. The system <NUM> includes a liquid collection tray <NUM> that may be supported by a support structure within the reactor <NUM>, for example, a support ring or other structures not shown. The liquid collection tray <NUM> preferably extends substantially across the area of the reactor <NUM> to restrict fluids from bypassing the mixing zone <NUM>, and openings are typically provided through the liquid collection tray <NUM> to allow distribution of fluids to the inferior catalyst bed <NUM>. At least a portion of the liquid collection tray <NUM> collects fluids traveling downwardly from the superior catalyst bed <NUM> thereon.

Referring to <FIG>, a mixing device <NUM> is provided for mixing liquid and vapor within the quench zone <NUM>. The mixing device is preferably supported by the liquid collection tray and is positioned thereabove, although the mixing device <NUM> may be positioned below the liquid collection tray, or have portions thereof above or below the liquid collection tray <NUM>. By one aspect, the mixing device <NUM> is supported on the liquid collection tray <NUM> and includes an outer wall <NUM> separating the mixing device <NUM> from a liquid collection zone <NUM>. The outer wall <NUM> may be generally circular as illustrated or may be polygonal or another suitable shape. The liquid collection zone <NUM> may include a gap between the outer wall <NUM> and the reactor wall <NUM> extending entirely or at least a portion about the outer wall <NUM>. During operation, liquid from the superior catalyst bed <NUM> is collected in the liquid collection zone <NUM>. In one example, in order for the liquid collecting zone to provide sufficient space for existing reactor shell attachments, installation of the mixing device and for accommodating the quench distributor <NUM> the outer wall <NUM> is positioned between <NUM> and <NUM> in. from the reactor wall. In another example it is between <NUM> and <NUM> in. from the reactor wall. By one approach, a baffle <NUM> extends across the liquid collection zone to facilitate flow in a single direction about the mixing device outer wall <NUM> to improve pre-mixing of the liquid. As illustrated in <FIG>, to provide additional mixing area within the mixing device <NUM>, by one aspect the outer wall <NUM> may be positioned in close proximity or adjacent to the reactor wall <NUM>. In one approach, the outer wall <NUM> is positioned between <NUM> and <NUM> in. from the reactor wall. To provide sufficient area for liquid collection, in this approach, a liquid collection well <NUM> may be provided in a gap in the outer wall <NUM>.

The mixing device <NUM> includes a mixing channel <NUM> for mixing vapor and liquid. The mixing channel <NUM> is one or more elongate channels to facilitate the flow of liquid and vapor therethrough. Since vapor flows through the mixing channel <NUM>, at least a portion of the mixing channel <NUM> is substantially enclosed to maintain vapor within the mixing channel <NUM> during mixing. As illustrated in <FIG>, the mixing channel <NUM> is an elongate generally annular channel extending about the center axis of the reactor <NUM> and/or the mixing device <NUM>. The annular mixing channel <NUM> may be round as illustrated, polygonal or other shapes. By one aspect the mixing channel <NUM> is formed between the outer wall <NUM> and an inner wall <NUM>. The outer wall <NUM> and inner wall <NUM> may be formed by baffles extending upwardly from the mixing channel bottom wall <NUM>, which may be a portion of the liquid collection tray. The outer wall <NUM> and inner wall <NUM> may include two or more separate baffles as illustrated in <FIG> or a single baffle extending in an inwardly swirling pattern.

By one aspect, the mixing channel <NUM> includes a liquid inlet <NUM> at an inlet end portion <NUM> thereof and an outlet <NUM> at an outlet end portion <NUM> thereof. In one approach the liquid inlet <NUM> includes an opening <NUM> in the side of the outer wall <NUM> or other wall of the mixing channel <NUM> at the inlet end portion <NUM>. It should be noted that as used herein, the term "opening" refers to any type of opening or other structure capable of providing the passage of fluid therethrough, including, but not limited to apertures, nozzles, perforations, slots, tubes, and spouts. The liquid inlet opening <NUM> may be positioned at a lower portion of the mixing channel <NUM>. In this regard, liquid collected on the liquid collection tray <NUM> can enter through the opening <NUM>, however, the low position of the opening <NUM> allows liquid to flow through preferentially than vapor. To this end, the liquid inlet opening <NUM> may be formed with a top portion <NUM> near or beneath an expected operating liquid level above the liquid collection tray <NUM> at full vapor and liquid design loading. The opening is positioned at a bottom <NUM>% of the height of the mixing channel <NUM> and in one example, at a bottom <NUM>% of the height of the mixing channel <NUM>. In one example, at least <NUM>% of an open area of the liquid inlet opening <NUM> is in a bottom <NUM>% of the height of the mixing channel <NUM> and in a bottom <NUM>% of the height of the mixing channel in another example. In this manner, fluid flowing through the liquid inlet is comprised substantially of liquid. In one approach, at least <NUM>% of opening is for liquid flow. In another example, at least <NUM>% of the opening is for liquid flow.

Liquid entering the liquid inlet <NUM> travels through the mixing channel <NUM> and in a generally downstream direction toward the outlet <NUM>. By one aspect, the mixing device includes one or more vapor inlets for passing vapor from an upper catalyst bed and outside of reactor into the mixing channel <NUM>. The vapor inlet <NUM> is positioned along the mixing channel <NUM> downstream of the liquid inlet <NUM> for improving contacting of the vapor with the liquid which passes through the mixing channel <NUM>. A vapor inlet opening <NUM> may be provided in the outer wall <NUM> of the mixing channel, and may be positioned at a bottom portion of the mixing channel <NUM> to improve vapor-liquid contacting as the vapor enters through the vapor inlet opening <NUM> even when the level of the liquid flowing through the mixing channel <NUM> is relatively low. In one approach, a mixing channel weir <NUM> may extend across a portion of the mixing channel <NUM>. The weir <NUM> maintains a minimum amount of liquid in the mixing channel so that vapor will contact liquid even when only a small amount of liquid flows through the mixing channel <NUM>, for example during startup or shutdown. The weir can be positioned in various angles relative to the mixing channel for improving liquid mixing. In one example the opening <NUM> is positioned at a bottom <NUM>% of the height of the mixing channel <NUM>. In another example, the vapor inlet opening <NUM> is positioned at a bottom <NUM>% of the height of the mixing channel <NUM> and at a bottom <NUM>% of the height of the mixing channel <NUM> in another example. In one example, at least <NUM>% of an open area of the vapor inlet opening <NUM> is in a bottom <NUM>% of the height of the mixing channel <NUM> and in a bottom <NUM>% of the height of the mixing channel <NUM> in another example.

According to one aspect, a vapor chimney <NUM> surrounds the vapor inlet opening <NUM>. The vapor chimney <NUM> includes a chimney wall that extends up from the collection tray and includes an upper chimney inlet or opening <NUM> to provide for passage of vapor into the chimney <NUM> and through the vapor inlet opening <NUM>. The vapor chimney opening <NUM> may be at the top of the chimney <NUM> or an aperture through the chimney wall at a first height above the liquid collection tray <NUM>. Unless specified, as used herein, upper opening refers to one or more openings that are elevated above a bottom wall or liquid level, for example the liquid collection tray <NUM> or a bottom wall of a portion of the mixing device <NUM>, and may include, but are not limited to openings in a top or side of a vapor chimney. The opening <NUM> is preferably positioned at a height above the liquid collection tray <NUM> above a normal operation liquid level to restrict liquid from entering the chimney <NUM> and through the vapor inlet <NUM> with the vapor. In one example, at least <NUM>% of the fluid entering vapor inlet <NUM> is vapor. In another example, at least <NUM>% of the fluid entering vapor inlet <NUM> is vapor.

The vapor inlet opening <NUM> may include one or more openings through the outer wall <NUM> of the mixing channel <NUM> as illustrated in <FIG> and <FIG>. Alternatively, according to various aspects, the vapor inlet chimney <NUM> may extend into the mixing channel <NUM> and the vapor inlet opening <NUM> may be formed in the chimney wall. In any event, the opening <NUM> is in fluid communication with the mixing channel <NUM>, and vapor entering the mixing channel <NUM> from the vapor inlet opening <NUM> may be introduced into the mixing channel <NUM> generally across the mixing channel <NUM> and into and across the liquid stream traveling therethrough. It has been identified injecting or dispersing the vapor toward and across the liquid stream in this manner provides improved intimate contact between the vapor and liquid in the channel and improved mixing of the liquid and vapor as compared to introducing the vapor and liquid streams into a mixing channel together through a common opening with vapor atop of liquid. Further, creating a sufficient pressure drop in the vapor chimney causes the vapor to be dispersed into the mixing channel <NUM> with sufficient velocity and momentum to travel across the downstream flowing fluid stream to improve mixing. In one example, the pressure drop through the vapor chimney <NUM> may be between <NUM> kPa (<NUM> psi) to <NUM> kPa (<NUM> psi), between 2kPa (<NUM> psi) and <NUM> kPa (<NUM> psi) in another example, and between <NUM> kPa (<NUM> psi) and <NUM> kPa (<NUM> psi) in yet another example.

Further, injecting the vapor into a liquid swirling about an annular mixing channel or a liquid with turbulent flow provides additional mixing due to the flow of the vapor and liquid together once the vapor has been introduced. The vapor may be directed through the vapor openings transversely or obliquely to the mixing channel. As mentioned, by one aspect, as illustrated in <FIG>, the vapor inlet includes two or more openings <NUM> positioned at different heights above the liquid collection tray <NUM>. Providing the openings <NUM> at different heights allows the optimum contact between vapor and liquid.

While introducing the vapor orthogonally or near orthogonally to the liquid stream flowing therethrough has been shown to provide good mixing, introducing the vapor in an oblique downstream direction relative to the mixing channel outer wall <NUM> may provide good mixing while reducing interruption with the flow of fluid in the downstream direction. In this regard, by one aspect, baffles <NUM> may be provided for directing the vapor entering the mixing channel downstream and obliquely to the liquid stream. The baffles <NUM> may extend from the opening at an acute angle to the outer wall <NUM> as illustrated in <FIG>. In one example the baffles extend generally downstream at an acute angle to the mixing channel outer wall <NUM>. In one example, the acute angle is between <NUM> and <NUM> degrees, and <NUM> and <NUM> degrees from outer wall <NUM> in another example.

In one aspect, one or more additional vapor inlets <NUM> having vapor inlet openings are positioned downstream of the liquid inlet <NUM> at different downstream distances than the first vapor inlet <NUM>. It has been identified that providing two or more vapor inlets at different positions along the mixing channel <NUM> may improve vapor-liquid contacting by gradually directing the vapor into the liquid stream as the liquid stream passes through the mixing channel. The additional vapor inlets <NUM> may also include vapor chimneys <NUM> having upper openings. The heights of the upper chimney openings <NUM> and <NUM> of the different vapor chimneys may be different such that a chimney having a lower opening height may provide liquid overflow into the vapor chimney and through the vapor inlet in the event of excess liquid accumulation on the liquid collection tray <NUM> during operation. By providing other chimneys having higher upper chimney opening heights above the tray <NUM>, those chimneys may still restrict excess liquid from entering the chimney with the vapor, allowing primarily vapor to pass through the chimney and into the mixing channel, maintaining vapor-liquid contacting therein. Although various combinations of vapor inlet chimney upper opening heights are possible, preferably an upstream chimney has a lower low opening height than a downstream chimney (downstream along the mixing channel). In this regard, if the liquid level in the liquid collection zone rises, the liquid can overflow into the upstream chimney while vapor still flows through the downstream chimney to contact the liquid that bypassed the liquid opening and entered the mixing channel <NUM> via the upstream chimney.

As described further below with regard to <FIG>, by one aspect the mixing channel includes an outer mixing channel <NUM> and an inner mixing channel <NUM> positioned inwardly of the outer mixing channel <NUM>. In accordance with this aspect, one or more internal vapor inlets <NUM> may be provided within the mixing channel to provide vapor to the inner mixing channel <NUM>. The internal vapor inlet <NUM> includes a chimney vapor opening <NUM> through a wall of the inner mixing channel <NUM> or through a chimney <NUM> of the internal vapor inlet. Similar to the vapor inlet <NUM>, the internal vapor inlet opening <NUM> may be positioned in a lower portion of internal mixing channel <NUM> so that the vapor entering the mixing channel <NUM> through the opening <NUM> is directed toward the liquid stream flowing therethrough. An internal chimney upper opening <NUM> may extend above the top plate <NUM> to allow vapor to pass from above the top plate through the chimney <NUM> and into the inner mixing channel <NUM>. In one approach, the chimney opening may be positioned above an upper surface of the top plate <NUM> to restrict liquid from entering the chimney <NUM> along with vapor.

As mentioned, the mixing channel <NUM> includes inner and outer walls <NUM> and <NUM> for defining a fluid passageway. The mixing channel <NUM> further includes a bottom wall <NUM> and a top wall <NUM>. The bottom wall <NUM> may include a portion of the liquid collection tray <NUM> beneath the mixing channel. The top wall <NUM> may be provided in the form of top plate or tray <NUM> covering at least a portion of the mixing channel <NUM>. In one approach, the inner and outer walls <NUM> and <NUM> include one or more baffles attached to and extending upwardly from the liquid collection tray <NUM>. Preferably top portions <NUM> and <NUM> of the one or more baffles are at similar heights above the liquid collection tray so that the top plate <NUM> can be positioned in close proximity or contacting the top portions <NUM> and <NUM> to provide a generally enclosed mixing channel <NUM>. The top plate <NUM> may be supported, at least partially, on the baffles or it may be supported by other structure. In this respect, flanges may be provided at the top portions <NUM> and <NUM> to support and/or attached the top plate.

As illustrated in <FIG>, by one aspect the outer wall <NUM> includes a baffle <NUM> extending about a center portion of the reactor <NUM> and spaced from the reactor walls. The inner wall <NUM> may be formed by another baffle <NUM> adjacent to or contacting an inner surface of the outer wall <NUM> and extending therefrom. It should be noted that each baffle may be formed from a single piece of material or two or more pieces of material joined together. By another aspect, as illustrated in <FIG>, the outer wall <NUM> is positioned in close proximity to the reactor wall and a baffle <NUM> extends in an inward spiraling pattern toward the center portion <NUM> of the reactor so that the baffle <NUM> serves as both the inner wall <NUM> and the outer wall <NUM> of the mixing channel <NUM>. In yet another example, as illustrated in <FIG>, the inner wall <NUM> may be formed from a baffle <NUM> separate from and spaced inwardly from a baffle <NUM> forming the outer wall <NUM>. In this approach, a separator baffle <NUM> may separate the inlet end portion <NUM> from an outlet end portion <NUM> of the mixing channel <NUM>. The separator baffle <NUM> may also serve as a contact surface to disrupt the swirling flow of fluid through the mixing channel <NUM> before the fluid exits the mixing channel <NUM> and enters a distribution zone <NUM> of the mixing device <NUM> to facilitate separation and distribution of the vapor and liquid therefrom.

As mentioned previously, by one aspect, the mixing channel <NUM> can include an inwardly spiraling channel having an outer channel portion <NUM> and an inner channel portion <NUM> positioned inwardly therefrom as illustrated in <FIG>. An intermediate wall <NUM> may be positioned between the outer wall <NUM> and the inner wall <NUM> and may be formed of the same or a different baffle from the one or more baffles forming the outer wall and the inner wall. Alternatively, the outer wall <NUM> can be positioned in close proximity to the reactor wall as illustrated in <FIG> with only a single mixing channel <NUM> to provide a wider mixing channel.

By one aspect, the mixing system <NUM> further includes a distribution zone <NUM> for distributing the fluid from the mixing device to a final vapor and liquid distribution tray <NUM>. The distribution zone <NUM> may include an inlet portion <NUM> in fluid communication with the outlet end portion <NUM> of the mixing channel <NUM>. The distribution zone <NUM> may be generally coplanar with the mixing device <NUM> to reduce an overall height of the mixing device <NUM> and the necessary interbed space required between the superior and inferior catalyst beds <NUM> and <NUM>. As is typical, a final distribution tray <NUM> may be included below the mixing device, including the distribution zone <NUM>, for providing high quality fluid distribution across the inferior catalyst bed <NUM>.

By one aspect, the distribution zone <NUM> includes one or more liquid distributors <NUM> and one or more vapor distributors <NUM>. In one approach the liquid distributors <NUM> include openings <NUM> through a bottom portion of the distribution zone <NUM>, for example a distribution zone bottom wall <NUM>. The vapor distributors <NUM> may include one or more openings or vapor distribution chimneys <NUM>. The vapor distribution chimney <NUM> includes an outer wall to restrict liquid flow through the chimney <NUM> and an upper opening to allow passage of vapor into and downward through the chimney. The vapor distribution chimney <NUM> includes a bottom opening <NUM> through the distribution zone bottom wall <NUM> to allow vapor to pass downwardly therethrough. The distribution zone bottom wall <NUM> may be formed by a portion of the liquid collection tray <NUM> extending below the distribution zone <NUM>. By one aspect, the mixing device <NUM> includes an annular mixing channel <NUM> and the distribution zone <NUM> is positioned inwardly of the mixing channel toward a center portion of the mixing device <NUM> with an inlet portion <NUM> of the distribution zone <NUM> in fluid communication with the mixing channel outlet portion <NUM>.

By one aspect, the distribution zone <NUM> includes a liquid separation and distribution zone <NUM> as illustrated in <FIG>. The zone <NUM> may be provided for separating liquid and vapor and distributing the liquid therebelow. The zone <NUM> includes a channel <NUM> between an outer wall <NUM> and an inner wall <NUM>. The channel <NUM> may have an arcuate or annular configuration, or other suitable shape such as, for example, polygonal, and be positioned within the annular mixing channel <NUM>. In this regard, the mixing channel inner wall <NUM> may form all or a portion of the channel outer wall <NUM> such that they are provided via a common baffle extending upwardly from the bottom wall and/or liquid collection tray <NUM>. A center vapor distribution chimney <NUM> may have a chimney wall that forms the inner wall <NUM> of the channel. Without intending to be bound by theory, it is believed that as the fluid passes from the outlet of the mixing channel <NUM> through the channel <NUM>, the centrifugal forces acting on the fluid as it swirls around the liquid separation channel <NUM> causes the heavier liquid to separate from the vapor. The liquid distributors <NUM> may be provided in the bottom wall <NUM> of the liquid separation channel for so that the liquid is collected on the bottom wall <NUM> and distributed therebelow through the distributors <NUM>.

As illustrated in <FIG>, by one aspect, a center vapor distribution chimney <NUM> may be positioned inwardly of the liquid separation channel <NUM>, and as mentioned above, form an inner wall of the liquid separation channel <NUM>. The vapor distribution chimney <NUM> may have a chimney wall <NUM> extending above the bottom wall of the distribution zone bottom wall <NUM>. The distribution chimney includes an upper opening <NUM>. The vapor chimney allows vapor to pass through the upper opening while restricting the flow of liquid therethrough. By one aspect, the vapor distribution chimney wall <NUM> extends upwardly only part-way to an upper wall of the distribution zone, which may be a portion of the top plate or a separate wall. In this regard, the upper opening is provided between an upper portion of the distribution chimney wall <NUM> and the top plate <NUM>. As shown in <FIG>, a spacer <NUM> may be provided above the chimney wall <NUM> between the upper portion thereof and the top plate <NUM> to support the top plate <NUM> thereabove. The spacer <NUM> may include one or more bars or other obstructions extending across the vapor chimney. In one example, a generally X-shaped support <NUM> is positioned between vapor distribution chimney <NUM> and the top plate <NUM> to support the top plate <NUM>. The support may advantageously arrest the swirling flow of vapor in the distribution zone <NUM>.

According to another aspect, as illustrated in <FIG>, the distribution zone <NUM> may include a bottom wall having a plurality of liquid outlets <NUM> therein. The outlets <NUM> according to this aspect may include a plurality of openings <NUM> through the bottom wall <NUM>. The openings <NUM> for liquid flow are preferentially positioned at locations such that the liquid flows from these opening will not fall on to top of the distributors on the vapor-liquid distribution tray below. The bottom wall <NUM> may include a portion of the liquid collection tray <NUM>. One or more vapor distribution chimneys <NUM> may extend upward from bottom wall <NUM>. Each vapor distribution chimney <NUM> includes a vapor chimney wall <NUM> and an upper vapor chimney opening <NUM> to restrict liquid from entering the vapor distribution chimney <NUM>. The vapor distribution chimney <NUM> encloses an opening <NUM> through the bottom wall <NUM> to vapor passes through the opening and is distributed therebelow.

By one aspect, the liquid distributor bottom wall <NUM> forms a part of, or is at least generally co-planar with, the liquid collection tray <NUM>. By another aspect, the bottom wall <NUM> may include a bottom tray <NUM> offset below the liquid collection tray <NUM> as illustrated in <FIG>. The bottom tray may extend beyond the distribution zone <NUM> and below at least a portion of the mixing channel <NUM>. In this manner, the bottom tray <NUM> has a larger cross sectional area than is possible where the bottom wall <NUM> is co-planar with the liquid collection tray <NUM> to provide for improved distribution therefrom. The expanded rough liquid distribution zone will reduce liquid height gradient and liquid momentum flux on vapor-liquid distribution tray below. In this approach, the distribution zone may include at least one opening <NUM> therethrough for passing fluid to the bottom tray <NUM>. By one aspect, the one or more vapor distribution chimneys <NUM> may extend up from the bottom tray <NUM>, through the opening <NUM>, and into the distribution zone <NUM>. In this regard, the bottom tray <NUM> may be spaced closely to the liquid collection tray <NUM> while still providing for sufficient vapor distribution chimney wall height. In one example, the bottom tray is spaced between <NUM> (<NUM> in) and <NUM> (<NUM> in. ), in another example between <NUM> (<NUM> in) and <NUM> (<NUM> in. ), and in yet another example between <NUM> (<NUM>. 5in) and <NUM> (<NUM> in. ) from the liquid collection tray <NUM>. The distribution zone can also be expanded into the bottom of mixing channel by raising the bottom of the mixing channel above the collection tray so that the distribution zone is co-planar with the liquid collection tray.

As described previously, the mixing device <NUM> may include a top plate <NUM> for providing a cover for the mixing channel <NUM> and/or distribution zone <NUM>. The top plate <NUM> may be positioned near the bottom portion of the superior catalyst bed <NUM>. It should be noted, that as used herein, the terms superior catalyst bed <NUM> and inferior catalyst bed <NUM>, refer respectively to a catalyst bed system above the mixing stage and a catalyst bed system below the mixing stage, including supports and any other parts of the catalyst bed system as are generally understood in the art. The top plate <NUM> is preferably spaced from the bottom portion of the superior catalyst bed <NUM> so that it does not restrict the flow of fluid descending therefrom. In this regard, descending fluid may contact and/or accumulate on an upper surface <NUM> of the top plate <NUM>.

The top plate <NUM> may be configured to direct fluid in a desired manner. For example, the top plate may include weirs, an inclined surface, or other suitable features to direct fluid into a liquid collection zone <NUM> or a liquid collection well <NUM>. For example, referring momentarily to <FIG>, an opening or space may be provided in the top plate <NUM> above the well <NUM> to allow fluid to pass therethrough.

According to one aspect, the system for providing a quench gas and mixing vapor and liquid between the superior <NUM> and inferior <NUM> catalyst beds includes a quench gas distributor <NUM> as illustrated in <FIG>. The quench gas distributor <NUM> may be positioned within the reactor walls and configured to dispense a quench gas toward fluid descending from the superior catalyst bed <NUM> to cool the fluid. The quench gas distributor may include a quench gas line <NUM> in communication with a quench gas source (not shown). The distributor may include a line, tube or pipe <NUM> extending about at least a portion of the interior of the reactor <NUM>.

As illustrated in <FIG>, the quench gas distributor includes an arcuate pipe extending along the inner surface of the reactor wall between the reactor wall <NUM> and the mixing device <NUM>. The pipe <NUM> includes a plurality of quench gas outlets or nozzles <NUM> for dispensing the quench gas. The nozzles <NUM> may include any suitable outlet. By one aspect, the nozzles are positioned above an operation liquid level of the liquid collection tray <NUM> so that liquid does not enter the nozzles. It has been identified that hydrocarbon liquid entering the nozzles may harden upon shutdown of the system when the hydrocarbon liquid cools and block the nozzles for future use. In one approach, the nozzles <NUM> are positioned near a bottom portion of a superior catalyst bed <NUM>. The nozzles <NUM> may be configured to direct quench gas generally horizontally across the reactor to contact fluid descending from the upper catalyst bed <NUM>, although the nozzles may also direct the quench gas in other directions. In one approach, the nozzles are configured to direct fluid between the upper surface of the top plate <NUM> and the catalyst bed. In this manner, intimate contact may be made between the quench gas and the descending fluids.

In another example, as illustrated in <FIG>, the quench gas distributor <NUM> may be positioned to direct quench gas toward fluids flowing from the top plate <NUM>. For example, the quench gas distributor may be positioned to direct quench gas toward a mixing channel outer wall <NUM> to contact fluids cascading down from the top plate <NUM>. In one approach, as illustrated in <FIG> and <FIG>, a weir <NUM> may be provided about at least a portion of the top plate <NUM>. The weir <NUM> may include an opening <NUM> so that fluids are directed through the opening <NUM>. The nozzles <NUM> may be configured to direct the quench gas toward the opening <NUM> to increase the amount of contact between the quench gas and the fluids. The opening may include one or more apertures in the weir, a gap in the weir, a low portion of the weir, or any other type of opening that facilitates the flow of fluids therethrough. By one approach, the opening may include a low portion <NUM> of the weir <NUM> having an irregular upper portion, such as the zigzag pattern illustrated in <FIG>.

The quench gas distributor <NUM> may be positioned within the liquid collection zone <NUM>, as illustrated in <FIG>, or only extend about a portion of the reactor as illustrated in <FIG> and <FIG>.

In another example, illustrated in <FIG>, the quench gas distributor may be configured to direct quench gas downward toward liquid in the liquid collection tray <NUM>. Also, as illustrated in <FIG>, the quench gas distributor <NUM> may be partially or completely submerged in liquid on the liquid collection tray <NUM> to improve contacting between the quench gas and the liquid on the liquid collection tray <NUM>. However, as discussed above, care should be taken so that hydrocarbon fluid does not harden within the quench gas distributor nozzles <NUM> when it is cooled.

By one aspect, a final distribution tray <NUM> may be positioned below the mixing device <NUM> for final distribution of the liquid to the inferior catalyst bed <NUM>. Suitable final distribution trays are commercially available, and one such tray is described in <CIT>. While this description has been provided with regard to specific embodiments, it is to be understood that this description should not be limiting to the disclosed embodiments, but it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

A first embodiment of the invention is a device for fluid contacting in a downflow vessel, comprising a liquid collection tray <NUM>, wherein at least a portion of the liquid collection tray <NUM> is configured to collect thereon fluids travelling downwardly from a superior catalyst bed <NUM>;; an enclosed elongate mixing channel <NUM>, wherein at least a portion of the mixing channel <NUM> is substantially enclosed such that vapor is maintained within the mixing channel <NUM> during mixing;; a liquid inlet <NUM> providing fluid communication between the liquid collection tray <NUM> and the mixing channel <NUM>, wherein the liquid inlet <NUM> includes at least one opening <NUM> in a wall <NUM> of the mixing channel <NUM> positioned at a bottom portion of the mixing channel <NUM>, wherein the at least one opening <NUM> is positioned at a bottom <NUM>% of the height of the mixing channel <NUM>; and a vapor inlet <NUM> of the mixing channel <NUM>, downstream of the liquid inlet <NUM>, configured to pass vapor into the mixing channel <NUM> wherein the vapor inlet <NUM> includes at least two openings <NUM> of the mixing channel <NUM> positioned at different heights above the liquid collection tray <NUM>. a vapor chimney <NUM> surrounding the vapor inlet <NUM>, having a chimney wall extending up from the collection tray and having an upper chimney opening <NUM> of the vapor chimney <NUM> at a first height above the liquid collection tray <NUM>. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising a second vapor chimney <NUM> surrounding a second vapor inlet <NUM> of the mixing channel <NUM> positioned at a different downstream distance from the liquid inlet <NUM> than the first vapor inlet <NUM>, and a second upper chimney <NUM> opening of the second vapor chimney <NUM> at a second height above the liquid collection tray <NUM> that is lower than the first height. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the vapor inlet includes an opening positioned in a lower portion of a mixing channel outer wall. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the vapor inlet <NUM> includes an opening <NUM> and a baffle <NUM> extending obliquely from the opening <NUM> into the mixing channel <NUM> in a downstream direction. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the chimney <NUM> is configured so that the pressure drop of vapor through the chimney <NUM> is between1.38kPa (<NUM> psi) to <NUM> kPa (<NUM> psi) An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the mixing channel <NUM> extends generally annularly. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the mixing channel <NUM> extends annularly and a baffle <NUM> extends between an inlet end portion <NUM> and outlet end portion <NUM> of the mixing channel <NUM> to separate the inlet end portion <NUM> from the outlet end portion <NUM>. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising a weir extending across the mixing channel at a first height and downstream of the vapor inlet to maintain a liquid level in the mixing channel. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, further comprising a top tray covering at least the mixing channel; a liquid collection well of the liquid collection tray for collecting liquid therein; and a space of the top tray providing communication between an upper surface of the top tray and the liquid collection well. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the top tray is configured to bias fluid on an upper surface of the top tray toward the top tray space. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein a mixing channel outer wall is spaced from edge portions of the liquid collection tray and liquid is collected therebetween. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein a mixing channel outer wall is in close proximity to edge portions of the liquid collection tray, and a liquid collection well including a gap of the mixing channel outer wall for collecting liquid therein.

A second embodiment of the disclosure is a device for contacting fluid in a downflow vessel and distributing the fluid there below comprising a liquid collection tray; an enclosed generally annular mixing channel having an outlet; a liquid inlet of the mixing channel having an opening at a bottom portion of the mixing channel for allowing liquid to enter the mixing channel; a vapor inlet downstream of the mixing channel and having a vapor inlet opening at a bottom portion of the mixing channel for directing vapor across liquid flowing through the mixing channel; and a liquid separation and distribution zone in fluid communication with the mixing channel outlet and positioned radially inwardly thereof for distributing fluid from the mixing channel to an inferior stage. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the liquid separation and distribution zone and the mixing channel are positioned above the liquid collection tray and are generally co-planar with each other to reduce an overall height of the device. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the liquid separation and distribution zone further comprises a separation channel with an arcuate outer wall and a plurality of openings through a bottom wall of the separation channel along and radially inwardly from the outer wall for separation of liquid and vapor. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the mixing channel spirals generally inwardly from the liquid inlet to the outlet thereof. An embodiment of the disclosure is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph, wherein the separation and distribution zone further comprises a separation channel with an arcuate outer wall and a plurality of openings through the collection tray along and radially inwardly of the separation channel outer wall for separation of liquid and vapor and passage of at least a portion of the liquid through the separation channel openings, and a distributor vapor chimney within the separation channel having an upper opening to allow vapor to pass through the distributor vapor chimney.

Claim 1:
A device for fluid contacting in a downflow vessel, comprising:
a liquid collection tray (<NUM>), wherein at least a portion of the liquid collection tray (<NUM>) is configured to collect thereon fluids travelling downwardly from a superior catalyst bed (<NUM>);
an enclosed elongate mixing channel (<NUM>), wherein at least a portion of the mixing channel (<NUM>) is substantially enclosed such that vapor is maintained within the mixing channel (<NUM>) during mixing;
a liquid inlet (<NUM>) providing fluid communication between the liquid collection tray (<NUM>) and the mixing channel (<NUM>), wherein the liquid inlet (<NUM>) includes at least one opening (<NUM>) in a wall (<NUM>) of the mixing channel (<NUM>) positioned at a bottom portion of the mixing channel (<NUM>), wherein the at least one opening (<NUM>) is positioned at a bottom <NUM>% of the height of the mixing channel (<NUM>); and
a vapor inlet (<NUM>) of the mixing channel (<NUM>), downstream of the liquid inlet (<NUM>), configured to pass vapor into the mixing channel (<NUM>),
wherein the vapor inlet (<NUM>) includes at least two openings (<NUM>) of the mixing channel (<NUM>) positioned at different heights above the liquid collection tray (<NUM>);
a vapor chimney (<NUM>) surrounding the vapor inlet (<NUM>), having a chimney wall extending up from the collection tray and having an upper chimney opening (<NUM>) of the vapor chimney (<NUM>) at a first height above the liquid collection tray (<NUM>).