MX2008007231A - Co-current vapor-liquid contacting apparatus - Google Patents

Abstract

The invention is a high capacity and high efficiency co-current vapor-liquid contacting apparatus for use in distillation columns (10) and other vapor-liquid contacting processes. The apparatus is characterized by an arrangement of modules (20) in horizontal stages rather than tray-like construction. The modules define a co-current contacting volume (56) and in an exemplary configuration the modules (20) include a liquid distributor (22), a demister (24), a receiving pan (26) and a duct (28). The modules of one stage are rotated to be non-parallel with respect to the modules of an inferior stage, a superior stage, or both. Variations relate to the design of the individual elements such as the demister, liquid distributor, ducts, and contacting volumes, and the overall arrangement of the apparatus.

Description

VAPOR-LIQUID CO-CURRENT CONTACT DEVICE BACKGROUND OF THE INVENTION The present invention relates to a device useful for performing fractional distillation or other forms of vapor-liquid contact for mass or heat transfer. More specifically, the present invention relates to a process and device that provides a co-current flow fractioning device of high capacity and high efficiency, useful in fractional distillation columns to remove volatile compounds such as hydrocarbons. The vapor-liquid contact devices, such as trays and fractionation packages, are used to perform an almost infinite variety of separations in the petroleum and petrochemical industries. Fractionation trays are used, for example, in the separation of several different hydrocarbons such as paraffins, aromatics and olefins. Trays are used to separate specific compounds such as different alcohols, ethers, alkylaromatics, monomers, solvents, inorganic compounds, atmospheric gases, etc., and in the separation of various boiling mixtures such as petroleum fractions including crude oil, naphtha and LP gas . The vapor-liquid contact trays are also used to carry out gas processing, purification and absorption. A wide variety of trays and others have been developed contact devices that have various advantages and disadvantages. Fractions and fractionation trays are the predominant form of conventional fractional distillation devices. They are widely used in the chemical, petroleum and petrochemical industries to promote the vapor-liquid contact that is made in fractionation columns. The normal configuration of a fractionation column includes 10 to 250 individual trays. Many times the structure of each tray in the column is similar, although it is also known that the structures alternate in vertically adjacent trays. The trays are mounted horizontally, typically at uniform vertical distances known as "separation of trays from the column". This distance may vary in different sections of the column. Many times the trays are supported by a ring welded to the inner surface of the column. Traditionally, fractional distillation has been carried out in cross-flow or countercurrent contact devices that have, in general, a descending liquid flow and an ascending vapor flow. At some point in the device, the vapor and liquid phases come into contact to allow the vapor and liquid phases to exchange components with each other and tend to equilibrium.

Then the vapor and liquid are separated, moved to the proper direction and contacted again with another quantity of the appropriate fluid. In many conventional vapor-liquid contact devices, vapor and liquid are contacted at each stage in a cross-flow arrangement. An alternative device differs from traditional multi-stage contact systems in that while the overall flow in the device continues in countercurrent, each stage of the actual contact between the liquid and vapor phases is carried out in a co-current mass transfer zone . During the fractional distillation process using conventional trays, the steam generated at the bottom of the column is raised by a large number of small perforations dispersed over the shelf area of the tray, which supports a quantity of liquid. The passage of vapor through the liquid generates a layer of bubbles known as "foam". The upper zone of the foam helps to quickly establish a compositional equilibrium between the vapor and liquid phases in the tray. Then the foam is allowed to separate into vapor and liquid. During the mass transfer, the vapor loses less volatile material to the liquid, and therefore becomes slightly more volatile when ascending through each tray. Simultaneously, the concentration of less volatile compounds in the liquid increases as the liquid descends from one tray to another. The liquid separates from the foam and descends to the next lower tray. This continuous formation of foam and vapor-liquid separation is carried out in each tray. Accordingly, the vapor-liquid contactors perform the two functions of contacting the rising steam with liquid, and then allowing the two phases to separate and flow in different directions. When the steps are performed an appropriate number of times on different trays, the process causes the separation of chemical compounds from their relative volatilities. Many different types of vapor-liquid contact devices have been developed that include gaskets and trays, as a result of the desire to perfect the equipment that has this utility in the chemical, refining and petrochemical industries. Each device tends to have its own advantages. For example, multiple descending trays have high vapor and liquid capacities, as well as the ability to operate effectively at a significant range of operating speeds. Structured packaging tends to have a low pressure drop, so they are useful in low pressure or vacuum operations. Two extremely important characteristics of the steam-liquid contact equipment in which improvements are always sought are capacity and efficiency. It is considered that a Co-current contact device is the one that achieves a high capacity through the use of vapor-liquid separation devices such as denebulizers or centrifugal vanes to increase the vapor-liquid separation in each stage. The co-current contact device can also achieve a high mass transfer efficiency through the co-current contact of fine droplets of liquid with steam. In the U.S. patent No. 6,682,633 describes a co-current liquid vapor contact device having a parallel arrangement, which reveals a modular device for co-current contact of vapor and liquid in several structural units placed in horizontal layers in a column or other compartment. The structural units are horizontally separated in each stage or layer, to provide spaces for the descending tubes of the modules of the next higher stage. The structural units of each stage are aligned parallel to the structural units in the upper and lower stages. The down tubes supply the liquid to one of the two inclined contact channels, where the contact channels discharge the vapor and liquid into separation chambers at the top of a module. The steam flows upwards, from the separation chambers to the contact channel of the next upper module, and the liquid flows down through a central descending tube unique to the next lower contact channel. U.S. Pat. Nos. 5,837,105 and 6,059,934 disclose a fractionation tray having multiple co-current contact sections dispersed through the tray. The liquid collected in a sump flows through a plurality of descending tubes to the next lower tray, where it is mixed with steam that rises through steam openings in the tray, and is passed to one of the two separation devices in the tray. The liquid from each separating device then flows into a sump. Several dispositions are revealed, including the parallel and non-parallel alignment of stages. If a failure occurs in the distribution of liquid or vapor in a vapor-liquid contact device having a parallel arrangement in adjacent stages, it is known that the fluid may not be easily redistributed throughout the device. Thus, poor distribution of liquid or vapor can spread from one stage to the next, reducing the capacity and efficiency of the device. Accordingly, a co-current liquid vapor contact device with an additional degree of freedom for redistribution of fluid is necessary. In addition, the use of perforated platforms on a relatively small surface inside the column can greatly increase the pressure drop, even if the fractional open surface is large.

Accordingly, a co-current vapor-liquid contact device with non-parallel stages and structures for transferring liquid from one stage to the next lower stage is necessary, without reducing the liquid handling capacity. In addition, such a device is required with optimal use of column space for fluid flow and contact to achieve high capacity and efficiency, and low pressure drop. SUMMARY OF THE INVENTION The present invention is a new high-capacity vapor-liquid co-current contact device and efficiency for use in fractionation columns and other vapor-liquid contact processes. The device is characterized by an arrangement of contact modules in horizontal stages, instead of a tray-like construction. The modules of a stage are rotated to be non-parallel with respect to the modules of a lower stage, an upper stage, or both. The contact modules include at least one liquid distributor and a denebulizer that define a contact volume. The rising steam enters the contact volume and drags the liquid that is discharged from the liquid distributor that transports it in a co-current direction to the de-aerator. The de-aerator, also known as a vapor-liquid separator, breaks off steam and liquid so that vapor and liquid can flow separately up and down, respectively, after being contacted. The liquid from the denebulizer flows into a receiving tank and through a duct. Each of the ducts associated with each receiving vessel directs the liquid to a separate liquid distributor, which is associated with a lower contacting stage. The variations refer to the number and design of each element, such as the denebulizer, the liquid distributor, the ducts, and the contact volumes, and the general arrangement of the device. In one embodiment, the present invention includes a device for performing the co-current vapor-liquid contact. The device comprises a plurality of stages having one or more contact modules. The contact module includes a liquid distributor having an outlet close to a contact volume, a receiver tank oriented essentially parallel to the liquid distributor, at least one duct, and a denebulizer. Each of the ducts has an upper end in fluid communication with the receiving tank, and a lower end in fluid communication with a separate lower liquid distributor. The denebulizer has an entrance surface close to the contact volume, and an exit surface superior to the receiving tank. The contact module of at least one stage is rotated with respect to the contact module of another stage. In another embodiment, the present invention includes a device for making vapor-liquid co-current contact. The device comprises a plurality of stages that have at least one contact module and a plurality of receiver cells. The contact module includes a pair of separate and essentially parallel denebulisers, and a liquid distributor located between the pair of denebulizers. The liquid distributor cooperates with the denebulizers to define a contact volume, and has an output in fluid communication with the contact volume. Each denebulizer of each module has an input surface in fluid communication with the contact volume, and an output surface greater than the receiving cell of each stage. At least one portion of the contact module is located between the pair of receiver cells associated with the pair of denebulizers. Each receiving vessel has at least one duct, and each duct of each receiving vessel provides fluid communication to a separate lower liquid distributor. At least one of the stages is rotated with respect to another stage, so that the contact modules of the two stages are in non-parallel alignment with respect to each other. In another of its forms, the present invention includes a vapor-liquid contact method. The method it includes the steps of passing a rising steam stream to a contact volume, and directing liquid through an outlet of a first liquid distributor to a contact volume. Drag the liquid into the steam stream within the contact volume to flow co-current to a de-nebulizer. Separate the liquid from the steam stream in a de-fogger. Supply the liquid that leaves the denebulizer to a receiving tank and pass the vapor current leaving the denebulizer to a higher contact volume. Pass the liquid from the receiving tank through at least one duct that directs the liquid to a lower liquid distributor. Each duct associated with a receiving tank directs the liquid to a separate lower liquid distributor. The lower liquid distributor is non-parallel with respect to the first liquid distributor. An advantage of the present invention is that the non-parallel orientation of a contact stage with respect to a vertically adjacent stage adds a degree of freedom to distribute the vapor and liquid in multiple directions. If a maldistribution of liquid or vapor occurs, the fluid is easily redistributed. Thus, a poor distribution of liquid or vapor is eliminated in only one or two stages, thereby increasing the capacity and efficiency of the devices of the conventional technique. The present invention also provides a passage relatively without obstructions of the vapor rising from a lower stage to a higher contact volume, which has the advantage of a lower pressure drop compared to the previous devices. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a cross section of a vapor-liquid contact column using the co-current contact modules of the present invention. Figure 2 is a cross section of a module. Figure 3 is a top view of a stage of the column of Figure 1, showing the de-aerators and the liquid dispenser. Figures 4A and 4B are views of the denebulizers of Figure 3. Figure 5 is a top view of a stage of the column of Figure 1, showing the receiving vessels and the liquid distributor. Figure 6A is a schematic top view of a receiving vessel of Figure 1. Figure 6B is a cross-sectional view of a receiving vessel of Figure 1. Figure 7 A is a schematic top view of a liquid distributor of the Figure 1. Figure 7B is an isometric view of the end of a liquid distributor of Figure 1.

Figure 8 is a cross-sectional diagram of a liquid distributor of Figure 1 having an alternative duct. Figures 9A-9G are extreme schematic views of various vapor-liquid separator structures of the present invention. Figures 10A-10B show alternative embodiments of contact modules of the present invention. The corresponding reference characters indicate corresponding parts in the various views. The examples described herein illustrate various embodiments of the present invention, but should not be construed in any way as limitations on the scope of the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, an embodiment of the co-current liquid vapor contact device of the present invention is shown within a container 10. The container 10 may be, for example, a distillation column, a absorber, a direct contact heat exchanger, or another container used to make vapor-liquid contact. The container 10 contains contact steps 12 in accordance with the present invention, and two optional manifolds / manifolds. An upper portion of the column contains the upper manifold / distributor 14 and the lower portion of the column contains the lower manifold / distributor 16. For simplicity, only three contact stages are shown. Co or is well known in the art, a distillation column can contain several sections. Each section may contain numerous contact stages, and there may be a plurality of feeds or fluid outlets between and within the sections. In addition, different contact devices can be mixed as co-current contact devices and other conventional distillation devices in the same section or different sections of the same column. The container 10 includes an outer layer 11 whose typical shape is cylindrical or, alternatively, any other shape. In the present embodiment, which is shown in Figure 1, each contact stage 12 is oriented with a 90 ° rotation with respect to the directly superior and inferior stages. Thus, each contacting stage 12 distributes liquid in a direction orthogonal to the immediately higher stage, and reduces the maldistribution of the liquid. In other embodiments, the vertically adjacent contact stages may be oriented with a rotation of between 0o and 90 °. In other embodiments, the contact stages are rotated between 9 ° and 90 °. The degree of rotation between the contact stages may be the same at each stage, or may vary. That is, the present invention also encompasses modalities in which the degree of rotation between vertically adjacent contact stages may vary. In the illustrated embodiment, each contact stage 12 comprises a plurality of contact modules 20 and receiving cells 26. As shown in Figures 2, 3, and 5, the contact modules 20 of this embodiment include a liquid distributor 22. located between a pair of denebulizers 24. The liquid distributor and the denebulizers cooperate to define the co-current contact volume of fluids 56. In addition to the contact modules 20, each stage also includes a plurality of recipient cells 26 possessing a plurality of ducts 28. Figure 5 illustrates a top view of two adjacent stages in which the denebulizers have been removed to more clearly show the arrangement of receiving cells 26, ducts 28, and liquid distributors 22. At each stage, the receiving cells 26 are separated and essentially parallel in the cross-section of the container. The liquid distributor 22 of a module is located between each pair of adjacent receiving cells 26, which results in an alternating pattern of receiving cells 26 and modules 20. The receiving cells located between two modules are designated in the present central receiving tanks, and the receiving cells located between a module and the container layer are designated in the present recipient cells terminals. It can be seen that the central receiver cells are shared by two adjacent modules. In another embodiment not illustrated, a pair of receiver cells is incorporated in each contact module. When these modules are arranged in essentially parallel alignment along the stage, the modules are adjacent in such a way that there are two receiving cells between each pair of adjacent liquid distributors. A vertical screen 21 is optionally included between two adjacent contact modules 20, in order to intercept the vapor emanating from the denebulizers 24 and, in general, to reduce any tendency of the emerging fluids to interfere with each other in the transfer volume of fluids 58 above the receiver cells 26. The vertical screen 21 is located between the demisters 24 of adjacent contact modules 20, and is essentially parallel thereto. The liquid dispenser 22 of the present embodiment has a liquid distributor inlet 32 in an upper portion and a plurality of outlets 34 in a lower portion. Two inclined walls of liquid distributor 30 cause the liquid distributor 22 to be tapered in the downward direction. The bottom of the liquid distributor, essentially V-shaped, can be pointed, curved or flat, as shown in Figure 2. Alternative modalities can be contemplated where the distributor of Liquids are in several different ways, such as staggered or inclined and staggered. In still other embodiments, the transverse shape of the liquid distributor may be regular, such as rectangular or square, or may be curved, irregular or with any other configuration, to define the desired contact volume, and supply liquid thereto. However, the V-shaped liquid distributor is used in the present embodiment to provide a combination of a large contact volume between the denebulizers 24 and the liquid wall distributor walls 30 in the lower portion of each stage 12, and a large liquid distributor inlet 32 in the upper portion to accommodate enlarged ducts 28 to increase liquid handling capacity. The inlet liquid distributor 32 is configured to be connected with the ducts 28. The optional inlet plates 36 are located between vertically adjacent liquid distributors. The inlet plates 36 of the liquid distributor cover the inlet of the liquid distributor near the liquid distributor outlets 34 of an upper liquid distributor 22. Two edges 38 in each inlet plate 36 direct liquid from the upper liquid distributor 22 to the volume above the demister 24, where the liquid is entrained by the rising steam. This provides an additional advantage to ensure high efficiency, where liquid is prevented enter the liquid distributor 22 directly from the upper liquid distributor, which would elude a contact opportunity. The liquid distributor outlets 34 are formed by a plurality of slots or other types of perforations disposed in one or more rows near the bottom of the liquid distributor 22. The outlets 34 may be located in the walls 30 and / or the bottom of the liquid distributor. In operation, a liquid level in the liquid distributor forms a seal which prevents the rising vapor from entering the liquid distributor through the inlets 34. The perforations 34 are preferably distributed along the liquid distributor 22, and can arranged so that the perforations are of varying sizes or numbers, or are disposed in the portions of the liquid distributor 22 that are above a lower liquid distributor. Accordingly, the arrangement of the outlets of the liquid distributor can be used as another way to prevent the liquid from flowing directly from a liquid distributor to a lower liquid distributor. The combinations of these and other devices that will be discussed later can be used to prevent this possibility that the liquid eludes a contacting step. The denebulizers 24 run along the liquid distributor 22 in rows on both sides thereof, as can be seen in Figure 3. It should be noted that the receiving cells are not shown in Figure 3, to better illustrate the orthogonal relationship of the modules in adjacent stages of the present embodiment. The rows of denebulizers 24 can be assembled from a plurality of de-fogging units 40 which are shown in Figures 4A and 4B. The de-fogging units 40 may further include a male end plate and a female end plate 48, where each cooperates with an end plate complementary to an adjacent de-fogging unit 40 to form a seal that essentially prevents leakage of fluid through the joints. These male and female end plates represent a type of interlocking mechanism that can be used to construct a row of denebulizers 24 from modular units of denebulizers 40. Any known interlacing mechanism can be used. In other embodiments, the modular units 40 may be held together by any device known as rivets, staples, bolts, crimps or bands, or by welding or glueing. Mechanisms such as the combination of flange and groove male and female can provide advantages for rapid assembly and disassembly. The modular configuration of the denebulizers 24 allows a manufacturer to produce defoamer units 40 in one, or a few standard sizes, to be assembled into rows of denebulizers 24 of variable length. Desizing units 40 of special sizes could be required for rows of particularly short defoamers 24, or to coincide with the length of a liquid distributor 22, depending on the dimensions of the device and the variety of standard size demister units 40 available. The modular design has the additional advantage that it facilitates the assembly of the contact module 20, since the de-fogging units 40 are lighter than a row of denebulizers formed in a single unit. However, in other embodiments a single denebulising unit 40 defines a complete row of denebulisers 24. The denebulising units 40 comprise a vapor-liquid separation structure 41 which may be of conventional design. Various known designs are used to de-drag drops of liquid from a vapor stream. An example are dehumidifiers, such as a blade-type demister, which have several channels and grilles, so that the fluid flow through the de-nebulizer must undergo several changes of direction, which causes droplets of liquid to collide. with portions of the separation structure 41 and flowing towards the bottom of the de-aerator. Another example of known vapor-liquid separation devices are meshes or interwoven metal wires. They can also be used combinations of these dew-removing technologies. As shown in Figure 2, several optional elements may cooperate with or incorporate into the denebulizer to further improve the performance or structural integrity of the device. For example, a perforated inlet plate 42 is shown as an inlet surface, a perforated outlet plate 44 as an outlet surface, and a non-perforated top plate 45. Perforated plates are a type of flow manipulator that can cooperate with the denebulizer. Other non-limiting examples of flow manipulators include expanded metal, porous solids, meshes, screens, gratings, screens, interwoven shaped wires and honeycombs. It has been found that the fractional open surface of the flow manipulators affects both the separation efficiency and the pressure drop of the de-nebulizer. The open fractional surface of the flow manipulators may vary on different sides and on the same side of the de-nebulizer, to optimize the separation efficiency and pressure drop of the de-nebulizer. Various types of flow manipulators can be used in a single denebulizer. In other embodiments, the flow manipulators are not used in some, or any, of the inlet and outlet surfaces of the denebulizer. The perforated entrance plate 42 is close to the liquid distributor 22. Perforated outlet plate 44 extends over most of the side of the denebulizer opposite the perforated inlet plate 42 and along the bottom of de-nebulizer unit 40. The non-perforated upper plate 45 prevents liquid exit defoaming unit 40 directly on top of the unit, and increase the vapor-liquid separation efficiency. The non-perforated top plate 45 has bands flexed on both sides, one that follows the wall of the liquid distributor 30 to join the wall, and the other that follows the perforated outlet plate 44 of the denebulizer 40 to connect to the outlet plate perforated 44. It has been found that the non-perforated strip extending a distance from the top of the perforated outlet plate 44 also improves the efficiency of vapor-liquid separation. In one embodiment, the band extends to cover 10% of the height of the denebulizer outlet. In another embodiment, the strip extends up to 30% of the height of the denebulizer outlet. In yet another embodiment, the band extends to 50% of the height of the denebulizer outlet. Each of the receiving cells 26 shown in Figures 2, 5, 6A, and 6B includes edges that extend vertically around a flat base 50. The de-nebulizer support rails 52 are formed by joining a metal plate formed at each of the two edges along the tub 26. The terminal receiving cells may include only one de-nebulizer support rail 52. The liquid collected in the receiving cell 26 is directed to the plurality of ducts 28 In one embodiment, the liquid receiving cell 26 includes an optional screen 54, which is shown in Figures 6A and 6B. The support rails 52 are joined to the base of the de-fogging units 40 in a particular row of denebulizers 24. A support angle attached to the bottom of each de-fogging unit 40 is inserted into the support rail 52, and the Top of the denebulizer to the wall of the liquid distributor 30, near the inlet of the liquid distributor 32. The support rails 52 provide structural support for the de-fogging units 40 even before the de-fogging units 40 have been attached to the liquid distributor 22. In this embodiment, each central receiving tank supports two rows of denebulizers 24, one from each of two adjacent contact modules 20, while the terminal receiving tanks next to the wall of the container 11 support a denebulizer of the terminal modules of The phase. Thus, two contact modules can share a receiving cell 26. Thus, as described for the present embodiment of the invention, the construction of each stage can be the same in at least part of a column, sowhich simplifies the manufacture and installation of the device. The plurality of ducts 28 extend through the receiving tank 26 and into the inlet of the liquid distributor 32. Each of the ducts 28 extending through a receiving tank 26 in particular directs liquid to a different lower liquid distributor 22. , as best shown in Figure 5. In the current embodiment, the upper part of the duct 28 is flush with the horizontal surface 50 of the receiving tank 26, whereby the liquid can flow freely from the receiving tank 26 towards the duct 28 without any obstruction. In other embodiments, the ducts may hang from the receiving tub having an edge resting on the flat base 50 of the receiving tub when the ducts are placed through the openings. The ducts can also be mounted on the bottom surface of the receiver cells. Any conventional way can be used to connect the receiving ducts and vats, including, without limitation, hanging, riveting, welding and press fitting. Packages or sealants can be used to prevent leakage between the receiving tanks and the ducts. In other embodiments, the ducts can be defined at least partially by the portion of the flat base of the receiving tub, which can be cut and bent or pushed when the openings are formed. In addition, the top mouth of the duct 28 can be widened to make it more wide that the inlet of the liquid distributor 32, as shown in Figure 2, to increase the liquid handling capacity, and reduce the drowning tendency at the inlet of the duct. The side walls of the ducts 28 are inclined, so that the ducts 28 remain inside the liquid distributor 22 and leave a gap for easy installation and purge of steam, which is shown in Figures 2 and 7. The steam can enter to the liquid distributor 22 with liquid flow from an upper stage, or through the outlets of the liquid distributor 34 when the outlets are not completely sealed by the liquid in the liquid distributor 22. If the vapor in the liquid distributor 22 it is not properly purged from the upper part of the liquid distributor 32, it will be forced into the ducts 28, which can choke the flow of liquid through the ducts, and thereby cause severe drag and premature flooding of the device. Accordingly, an advantage of the present embodiment is that the vapor in the liquid distributor 22 is purged by the separations between the ducts 28 and the liquid distributor 22, or the openings in the upper part of the liquid distributor 22 between the ducts 28. The bottom of the duct 28 opens with a plurality of nozzles or a continuous groove or a single large opening, to allow liquid to flow to the liquid distributor 22. Under operating conditions Normally, the ducts 28 are sealed against vapor flow, either dynamically by the liquid in the ducts 28, or statically by the liquid in the liquid distributor 22. In an alternative embodiment shown in FIG.

Figure 8, the duct 28 extends only slightly below the inlet of the liquid distributor 32, and has an opening in the bottom of the same size as the main body of the cross section of the duct 28. The duct 28 is not sealed by the liquid in the duct 28 or by the liquid in the liquid distributor 22. Instead, a sealing plate 37 can be installed and the inlet of the liquid distributor 32 closed. The ducts 28 are placed snugly by the inlets in the sealing plate, to prevent steam from entering the ducts 28 from the top of the liquid distributor 22. The first embodiment has an advantage over this alternative embodiment because if, in the alternative embodiment, steam enters the liquid distributor 22 through the outlets 34 or with the liquid flow from an upper stage, the steam is not purged from the top of the liquid distributor 32. Instead, steam is forced into the ducts 28 and towards the upper stage, which can choke the flow of liquid through the ducts. The volume between the inlet surface of a denebulizer 24 and the adjacent wall 30 of the distributor of liquid 22 forms a fluid contact volume 56, which is shown in Figure 2. Fluid contact continues in de-fogging units 40 before separating the vapor from the liquid. The perforated plate 42 or other flow manipulator at the inlet of the de-aerator improves the distribution of fluid flow to the de-nebulizer, and improves the vapor-liquid separation. The inlet flow manipulator can also improve fluid contact and mass transfer. The volume above a receiver cell 26 and between the rows of denebulizers 24 it supports defines a fluid transfer volume 58. The rows of denebulizers 24 can be oriented at an angle to the vertical, as illustrated in Figure 2, to provide an improved combination of a contact volume 56 which, in the present embodiment, has a decreasing volume from top to bottom, to coincide with the decreased fluid flow and a fluid transfer volume 58 which, in the present embodiment, It has an increasing volume, from low to high, to coincide with the increasing steam flow. The liquid dispenser 22 and receiver cells 26 can be supported by support rings (not shown) which are fixed to the inner surface of the column wall, by welding or other conventional means. The distributor of liquids 22 and tanks Receivers 26 can be riveted, stapled or otherwise secured to the support ring so that the liquid dispenser 22 and receiving cells 26 are held in their position during operation. In a particular embodiment, the end of the liquid dispenser 22 includes an end seal 59a and a clamp 59b, as shown in Figure 7B. The end seal 59a is welded to the end of the liquid distributor 22, thereby sealing the end of the liquid distributor 22. The clamp 59b is welded to the bottom of the end seal 59a, and is riveted, stapled or otherwise fixed to the support rings. The ends of the rows of denebulizers 24 and the receiving chambers 26 with the end seal 59a and the clamp 59b can be welded. In some embodiments, the liquid distributor 22 and the receiving cells 26 are the main supports for the contact module 20; however, it may be necessary to add additional support beams for significantly larger columns. In addition, reinforcing features such as ribs, clamps, increased material thicknesses and additional supports can be used with the liquid dispenser 22 and receiving basins 26. The ends of the liquid dispenser 22 can be configured in various ways to follow the contour of the container. container wall. For example, Figure 7A shows that the opposite ends of the liquid distributor 22 can follow the contour of the container wall stepwise or continuously. In some embodiments of the present invention, the denebulizer is a blade type dehumidifier having formed or corrugated sheets, flat sheets and integral grids. The corrugated sheets and the flat sheets are placed in layers, so that the arrangement of integral sheets and grids creates at least one tortuous channel of fluid flow, from an inlet to a steam outlet of the device. One compartment or outer frame is sufficient to hold the plates. Some variations include the order of the layers of corrugated sheets and flat sheets, and whether the grids are formed on the corrugated sheets, the flat sheets, or both. Other variations include the size and shape of the grids, as well as the size and shape of the corrugated sheets and the configuration of the outer frame. An advantage of this type of moisture scavenger is that the flat and corrugated sheets with grids simply form layers, to form a self-supporting spacer structure 41. That is, the sheets in layers and the defined fluid flow channels can maintain the separation desired without requiring other elements such as spacers, fasteners or welding. In addition, variations in the design of the blades and grids can be provided to achieve a high vapor-liquid separation, and at the same time prevent falls from unacceptable pressure. Although the outer frame may include solid and perforated plates as described and illustrated for the denebulisers of Figure 2, the frame may be a sloped or flat material that secures the edges of the sheets in layers and self-supported. In other modalities, belts or bands define the frame that joins the leaves together. A frame may comprise a variety of these and other commonly known elements for holding the sheets together. The frame can be secured by any known way. Non-limiting examples include welding, rivets, glue, fasteners, pressing, hinges and pressure fittings. Thus, the frame is sufficient to press the sheets with one another, so that the surfaces or points of joint in which the leaves in layer are joined are sealed, and a significant amount of fluid is not leaked through the joint points between leaves. The use of layers of corrugated and flat sheets, and of integral grids, to define a vapor-liquid separator structure of a denebulizer, has many variations, of which some non-limiting examples are shown in Figures 9A-9G. The separating structure 41 shown in Figure 9A includes formed (corrugated) sheets 60, sandwiched between two planar sheets 62. A plurality of integral grids 64 are formed by cutting and bending the sheets. formed sheets 60, as shown with dotted lines on the left side of Figure 9A. The vapor with entrained liquid flows generally in the direction of the arrows and through the gaps in the formed sheet 60 that remains through the formation of the grids 64. Droplets of liquid are trapped by the pockets formed by the grids 64, and they are therefore separated from the vapor as the vapor-liquid mixture passes through the flow channels of the de-nebulizer, as it is required to change direction several times. The steam continues through the spaces, and the liquid is drained downward, by the formed sheets 60 towards the lower portion of the perforated outlet plate 44. The separating structure 41 in Figure 9B shows a similar structure having formed sheets 60 and flat sheets 62; however, the grids 64 are rounded. The rounded shape reduces the pressure drop across the plates. Another design that reduces the pressure drop across the plates uses the diagonal grids 64 shown in Figure 9C. Figure 9C shows the spaces or separations between the corrugated sheets 60 and flat sheets 62, to clearly distinguish the layers of the two types of sheets. This separation is eliminated when the outer frame secures the sheets in layers with each other, and the denebulizer is complete. The separating structure 41 in Figure 9D includes the formed sheet 60 which has the grids 64 in addition to two flat sheets 62a and 62b between the corrugated sheets 60. The flat sheets 62a and 62b include screens 66a and 66b. The configuration results in bags oriented to and from the direction of fluid flow, which reduces re-entrainment of fluid and increases flow processing. An alternative embodiment shown schematically in Figure 9E is similar to the separation structure 41 of Figure 9D. However, the diagonal grids 64 are used to reduce the pressure drop across the plates. A further modification of the separating structure 41 of Figure 9E is shown in Figure 9F, and includes diagonal grids 64 and straight grids 66a and 66b. In yet another alternative embodiment of the separating structure 41, which is shown in Figure 9G, the formed sheet 60 does not contain grids and the flat sheets 62 include grids 66. In other embodiments not illustrated, the grids may have multiple flexures. To facilitate manufacturing and installation, the denebulizers, including their separating structures used in the present invention, will usually have the same configuration. Similarly, the configuration of each fluid flow channel in a denebulizer will be uniform. However, none of these is required. For example, terminal denebulizers may have a different configuration from central denebulizers, and fluid flow channelsnext to the end plates may have a different configuration from the other flow channels in the same denebulizer. In alternative embodiments, the denebulizing modules 40 use conventional separating structures, the designs of which may have many possible variations. An important factor is its effectiveness in separating liquid entrained from a stream of steam. At present, it is thought that this is related to the multiple obstructions to the fluid flow, which cause the liquid droplets to strike a solid surface. The closed path nature of the obstructions shown in the figures can result in the formation of relatively inactive regions, which also promote liquid separation. In some embodiments of the present invention, one or more manifolds / manifolds may be used. These devices are not required by the present invention, although they have the advantage of appropriately steering the vapor or liquid flows to maximize the vapor-liquid contact and the separation at each stage of the device. For example, in Figure 1 the upper part of the manifold / distributor 14 is shown, and includes a pipe distributor 70 and a through manifold 72. The pipe distributor 70 and the through manifold 72 direct the liquid towards the distributor. liquid distributor 22 of the upper contact stage 12. The upper manifold / distributor 14 also recovers the steam leaving the denebulizer rows 24 of the upper stage 12. The recovered vapor can be passed to a subsequent process or to a condenser to be reintroduced in part to the column as reflux liquid. In the absence of the upper manifold / distributor or other equivalent device, the descending liquid could flow to the fluid transfer volumes 58, and thereby bypass the vapor-liquid contact volumes of the upper stage. This liquid flow could also disturb the rising vapor vapor flow, and cause inefficiencies in one or more stages of lower contacts. The lower manifold / distributor 16 distributes steam below the lower contact stage, and collects liquid from the ducts 74 of the lower stage. The steam can be distributed between the ducts 74, instead of under them. The recovered liquid can be communicated to a subsequent process or to a boiler, to be reintroduced to the column in part, as steam. The ducts 74 in the lower stage may have a design different from that of the rest of the stages. For example, a continuous duct 74 may be used instead of a plurality of ducts 74 under a receiving trough 26. The openings in the receiving trough 26 are appropriately modified. In the absence of the collector / distributor lower or other equivalent device, a portion of the ascending vapor stream would bypass the vapor-liquid contact volumes of the lower stage, and would flow directly through the fluid transfer volumes. The rising steam could also re-entrain the liquid leaving the lower stage, and disturb the desired patterns of vapor and liquid flow. In addition to the above-described upper and lower manifolds / manifolds, additional manifolds / manifolds can provide a benefit at any point in the column into which a fluid stream is introduced or withdrawn, such as one or more feed streams or any other current product as a derivation. The fluid flow of a contact module 20 of an average stage 12 is described below. The liquid from an upper stage is directed to the liquid distributor 22 by several upper receiving tanks 26 through the ducts 28. The liquid leaves the liquid distributor 22 through the outlets of the liquid distributor 34, and enters the fluid contact volume 56. The ascending velocity of the vapor is high in the contact volume 56, and the liquid entering the contact volume 56 is entrained by the vapor. A portion of the liquid entering the contact volume 56 may fall on the inlet plate 36 at the top of a lower liquid distributor 22. The inlet plates 36, with edges 38, direct the liquid to the space possessing a high vapor velocity, where the liquid is drawn by the steam back to the contact volume 56. The inlet plate 36 on a lower liquid distributor prevents the flow of liquid pass directly from a distributor of liquid upper to the distributor of inferior liquid without having had contact with the steam. The entrained liquid is transported upwards by the steam to the inlet surfaces 42 of the de-fogging units 40. The steam and liquid are separated by the separating structures 41 within the de-fogging units 40, and the steam leaves the de-fogging units 40. through the outlet surface 44 towards the fluid transfer volume 58. The vapor then continues upwards, towards a contact volume 56 of an upper contacting stage 12. The liquid leaves the de-fogging units 40 through the lower portion of the outlet surface 44, and flows into the receiving vessel 26. The receiving vessel 26 directs the liquid towards the plurality of ducts 28, where each of the ducts 28 directs the liquid to a different lower liquid distributor 22. In an alternative embodiment, the contact stage 12 is arranged in a plurality of sections having parallel stages similar to those described in FIG.

U.S. patent No. 6,682,633. However, each of the parallel stage sections is rotated with respect to the upper and lower stages. The step in the transition from one section to the other includes features in accordance with the present invention, to allow the proper flow of fluid between the non-parallel sections. The ends of the contact module 20, that is, the terminal portions of the module 20 facing the inner surface of the wall 11 of the container, can be sealed to prevent the vapor or liquid from eluding the contact device. In this embodiment, the ends of the module 20 are inclined or curved to conform to the curvature of the structure containing them. Alternatively, the ends of the modules 20 are flat, and a non-perforated plate of horizontal extension spans the space of the module 20 to the surrounding wall of the container. Those skilled in the art will recognize that there may be many more variations in the basic arrangement of the present invention. For example, the angle of inclination of the walls of the liquid distributor 30 may vary significantly, from 0 ° to 30 ° or more. In one embodiment, the angle of the side wall of the liquid distributor 30 is essentially vertical to 8 ° with respect to the vertical. Another inclined surface is that of the vertical walls of the rows of denebulizers 24. In one mode, the angle is 8o from the vertical, and the angle can vary from 0o to 30 °. In some embodiments, the upper portion of the denebulizer is closer to the central plane of the imaginary vertical of the module than to the lower portion of the denebulizer. Another variation is that the modules 20 can be used in conjunction with trays and distillation packages, above, below or interspersed with column sections using the present device. The modules of the invention can also be used in split-wall distillation columns. Another variation refers to the shape of the surrounding container or column. Although most fractionation columns are cylindrical, this is not dictated by the present device, and can work equally well in a column with a different cross section geometry, such as rectangular or square. It is contemplated that a fractionation column could contain from 10 to 250 or more contact steps 12. The design of the modules 20 can be essentially uniform along the column in many installations; however, it can vary in a column, for example to accommodate changes in fluid flow velocities in different parts of the column. The figures do not illustrate all the options or additions in the basic device. The number of such Additions is great, since it includes additional supports, clamps, clamps, etc., of a general mechanical nature that can vary almost infinitely. The contact modules 20 can be symmetrical with respect to an imaginary central vertical plane that bisects the module along its entire length, as can be seen in the cross-sectional view of the module in Figure 2, where the module comprises a liquid distributor 20 between a pair of denebulizers. Another embodiment, in which the contact module also comprises the receiving cells and associated ducts on both sides of the denebulizers, can also be symmetrical. Figures 10A and 10B are presented to emphasize that the modules need not be symmetrical, and to illustrate several additional non-limiting embodiments of the present invention. For example, Figure 10A shows that the liquid dispenser 22 'does not need to extend all the way to the level of the receiving cell 26 of the stage. The end portions of the liquid distributor can be configured to provide support, extending to the support ring attached to the wall of the container, or other support mechanism mentioned herein, as well as any other known in the art. The liquid distributor 22 'also shows that the walls 30' and the portion bottom or bottom of the liquid dispenser can have various configurations, such as outlets 34 'which direct the liquid further down than laterally. Variations in the denebulizers are also illustrated by the left denebulizer 24 ', which is positioned vertically and is separated from the upper portion of the liquid distributor. The perforated upper plate 45 'is configured to extend over the gap between the liquid distributor 22' and the decanter 24 ', to essentially seal the upper portion of the contact volume 56' and thus ensure that the contacted vapor and liquid -current then be separated by flowing through the denebulizers of the stage. In another embodiment not illustrated, the vertical demister 24 'joins the liquid distributor in an upper portion of the wall 30'. The wall 30 'is configured to define the contact volume 56' in cooperation with the vertical denebulizer 24 '. Figure 10B shows that the upper part of the liquid distributor 22"may be below the top of the deicers 24", and that the duct 28"or the walls of the liquid distributor 30" or portions thereof may be essentially vertical . As shown, it is not necessary that the outlets 34"be arranged symmetrically, the denebulisers 24" may be located on the flat bases of the receiving cells, in a vertical or inclined configuration. The lower inner surface of the denebulizer may be sealed by a solid plate or an extension of the receiving vessel, to prevent the liquid separated in the denebulizer from flowing back to the contact volume 56. "Again, the solid upper plate 45" may be configured to extend to the liquid distributor if necessary, to essentially seal the upper portion of the contact volume 56. "Even if a solid top plate is not used, as shown for the denebulizer on the right side of the module shown in FIG. Figure 10B, there is provided a device for sealing the upper portion of the contact volume to prevent it from being dislodged from the denebulizers, Thus, it can be appreciated that the denebulizers may be in an essentially parallel alignment, even if their configuration is not identical. Well the contact modules 20 can be very short, it is anticipated that they will be longer than wide, with the width measured as the maximum distance between the perforated exit plates 44 of the opposite rows of denebulizers 24. The length of the modules 20 is dictated by the internal dimension of the column or container covered by the modules. The modules 20 can be manufactured to be self-supporting, or they can be supported through structural members extending through of the internal volume of the column. As with the de-fogging units 40, a liquid distributor in any module 20 can extend across the width of the column, or the liquid distributor can be manufactured as two or more individual sections joined together, end-to-end or by overlapping sections, to extend through the column. Similarly, the contact modules 20 can be manufactured as sectional units including each module element, and connected end-to-end as they are installed to form the rows of contact modules. In another embodiment, the modules 20 may be manufactured as units that are half-modules attached lengthwise, for example during installation. This can easily be seen if the module shown in Figure 2 were divided along the imaginary central vertical plane that bisects the module over its length. This half module could function as a complete module if the liquid distributor and the receiving vessel were complete in accordance with the teachings herein. Accordingly, in one embodiment a module may comprise a liquid distributor, a de-nebulizer, and a receiving vessel that has at least one duct. In many applications, each stage will include a plurality of contact modules; however, in some modalities a single module may be sufficient in one stage to achieve the desired vapor-liquid contact. The figures are only representations of the real device, and are not to scale. The size of the various components of the device will be set by the maximum fluid flow velocities to be accommodated in the device. To provide a criterion for the design of the device, it is noted that the inlet 32 of the liquid dispenser 22 will typically have a width of 8 to 25 cm. In other modalities, the width has a range of between 10 and 15 cm. The vertical distance between equivalent points in two layers of the device is within the range of between 25 and 75 cm. In other modalities, the vertical distance is between 30 and 45 cm. The de-fogging units 40 have a width of between 7 and 20 cm, measured between the vertical inlet and outlet surfaces 42 and 44. The bottom of the de-fogging unit 40 is 2.5 to 7.5 cm above the receiving tank 26, so that a separation is formed between the bottom of the de-fogging unit 40 and the receiving tank 26, to facilitate the drainage of liquid from the de-fogging unit 40 to the receiving tank 26, and for the flow of liquid from the receiving tank 26 to the ducts 28 In other embodiments, the de-fogging unit 40 rests on the flat bases 50 of the receiving vessel. In other embodiments, the bottom of the denebulizer is up to 15 cm above the receiving tank 26.

According to a particular embodiment, instead of the perforated entrance plates 42, a porous layer, such as a wire mesh, covers the entrance to the de-fogging units 40. It has been discovered that the use of this porous cover improves the steam separation -liquid especially during operation at higher vapor velocities. The porous cover may be of conventional mesh material used for dewatering liquid droplets, known as "dew eliminators." Typically it will comprise thinly interwoven strands, which form a low pressure drop cover of large area. The mesh cover is for a coalescence of small droplets and distribution of liquid to the separator.An alternative construction is to mount the mesh in an indentation in the separation structure 41, or completely within the denebulizing unit 40. Other materials, such as perforated plates, within the contact volume 56, to improve the vapor-liquid contact and the mass transfer The construction materials of the present device are those customarily used for vapor-liquid contact devices. invention can be considered the construction materials compatible with the vapor and liquid compositions, the s operating conditions of the vapor-liquid contact process, and the other construction materials used in the process. Common materials include metal of standard thickness, between gauge 7 and 30. The thickness of the metal required will vary in part depending on the strength of the metal and its composition. The metal can vary from semi-hard steel to stainless steel in more corrosive situations, or other metals, including titanium. The device can also be manufactured with composite and polymeric materials, including reinforced plastics. The device may be made of a single material as standard gauge metal or, alternatively, may be manufactured from a combination of materials. Another possible variation with the present device is to place a catalyst at various points within the device, such as inside the liquid distributor 22 or at other locations in the empty volumes used to transport steam or liquid, in order to perform catalytic distillation. The best placement of the catalyst will be determined in part if the desired reaction occurs in the liquid or vapor phase. The operating conditions for the fractionation column are confined by the physical properties of the compounds that are separated in the column. The temperatures and operating pressures of a column can be varied within these confines, to minimize the operating cost of the column, and accommodate other business objectives. The Operating temperature can vary from very low temperatures used in cryogenic separations, to temperatures that defy the thermal stability of the compounds. Accordingly, suitable conditions for the present process include temperatures in the wide range of between -50 to 400 ° C. The column is operated at a pressure sufficient to maintain at least a portion of the feed compounds present as liquid.

Claims (10)

1. CLAIMS 1. A device for making co-current vapor-liquid contact, comprising: a plurality of stages, which has at least one contact module and a plurality of receiver cells, wherein the contact module comprises; a) a pair of essentially parallel denebulizers separated from each other; b) a liquid distributor located between the pair of denebulizers and cooperating with the denebulizers to define a contact volume, where the liquid distributor has an outlet in fluid communication with the contact volume; and c) each denebulizer has an input surface in fluid communication with the contact volume, and an upper outlet surface for separating the receiving cells from this stage; wherein at least a portion of the contact module is located between a pair of receiving vessels, wherein each receiving vessel has at least one duct, where each duct of each receiving vessel provides fluid communication to a separate lower liquid distributor; and the contact module of at least one of the stages is in non-parallel alignment with respect to the contact module of another of the stages. The device of claim 1, wherein each of the ducts extends to the associated lower liquid distributor. 3. The device of claim 1, wherein each duct comprises an enlarged mouth, and wherein a vapor passage is formed between each of the ducts and the associated lower liquid distributor. 4. The device of claim 1, wherein at least one of the receiver cells is shared by two modules. The device of claim 1, wherein the denebulisers are supported by the receiving cells. The device of claim 1, further comprising an inlet plate that covers a portion of the liquid distributor near the bottom of a liquid top dispenser, wherein the inlet plate comprises a plurality of side walls configured to direct liquid to a volume that has a current of steam that flows inward. The device of claim 1, wherein at least one of the receiver cells further comprises a partition screen between at least two of the ducts. The device of claim 1, wherein the contact volume increases in the downward direction of the module. 9. The device of claim 1, further comprising a vertical outer container essentially closed containing the stages, where the container includes at least one feed inlet and two fluid outlets. 10. A method for contacting vapor-liquid, comprising the steps of: a) passing a rising steam stream to a contact volume; b) directing the liquid through an outlet of a first liquid distributor to the contact volume; c) dragging the liquid in the steam to flow co-current to a de-fogger; d) separating the liquid from the vapor in the denebulizer; e) passing the vapor stream leaving the denebulizer to a higher contact volume; f) supplying the liquid leaving the denebulizer to a receiving tank; and g) passing the liquid from the receiving tank through at least one duct directing the liquid to a lower liquid distributor; where each duct associated with one of the receiving vessels supplies liquid to separate lower liquid distributors, where the lower liquid distributor is in non-parallel alignment with respect to the first liquid distributor.