Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
  • B01F23/20—Mixing gases with liquids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/16—Fractionating columns in which vapour bubbles through liquid
  • B01D3/163—Plates with valves

Definitions

• This invention relates to a fluids contacting and dispersing apparatus and it particularly pertains to a novel valve assembly for use in fractionation columns and other related apparatus.
• a number of horizontally oriented surfaces or trays are mounted in a sealed, vertically oriented vessel known in the industry as a column or tower.
• Each of the trays may contain numerous openings.
• a relatively heavier fluid is introduced on the upper surface of the uppermost tray deck. The introduction of this fluid at one end of the horizontal tray is referred to as the upstream end or portion.
• a crossflow forms as the fluid flows across from the upstream end of the tray to the downstream end or portion of each tray.
• a weir which leads to a downcomer.
• the downcomer of an upper tray leads down to an unperforated upstream area or downcomer seal area on the next lower tray.
• a lighter fluid is introduced into the lower end of the column.
• Some columns utilize multiple sets of flow paths including a downcomer, active area and downcomer seal transition area for each section.
• valves associated within the tray openings and others have fixed assemblies over the holes or apertures.
• the valves may consist of generally flat plates or bubble caps to deflect the rising gases. These valves rise upwardly and fall due to gravity by the introduction of fluid pressure from below the valve.
• each individual valve introduces a small area of blockage across the each aperture of the tray deck thereby reducing the interaction or exchange between the fluids. This small, central area above each valve is a stagnant zone or an inactive area where minimal mass transfer exchange occurs.
• valve cover plate having opposed recesses into which an arched guide band is clipped to extend over the valve cover plate and downwardly through the recesses to guide the valve during when it is lifted by upwardly flowing fluid. Partial closure of the valve allows minimum free passage of fluid between the cover plate and the tray at all times. While the guide band of Van't Sant is useful in providing the easily assembled, two part valve body that it was intended to do, any fluid escaping upwardly under the guide band will be minimal and will not be directed towards the central stagnant zone over the valve cover plate leaving this zone undisturbed.
• This invention relates to a fluids contacting and dispersing apparatus of the type used in distillation and absorption systems for mass transfer exchange between two fluids of differing masses.
• a fluids contacting column, tray opening, fluid dispersing apparatus with a cover plate having at least one bleed fluid perforation.
• the cover plate is positioned over the tray opening to provide a fluid escape passage between the cover plate and a tray deck surface. Lighter fluid flows upwardly through the tray opening between the tray deck and the cover plate while heavier fluid flows across the tray deck surface.
• a bleed fluid deflecting member spans the fluid perforation from both side-to-side to provide at least two oppositely facing outlets.
• the configuration of the deflecting member disperses the fluid into two distinct bleed fluid streams which flow away from one another and passes over a central zone of the cover plate. These two bleed fluid streams are different in size from the fluid that passes between the cover plate and the tray deck at the fluid escape passage.
• the apparatus is a valve assembly and the cover plate rests over the tray thereunder by means of slidable legs. At least two legs are provided to slide in and extend downwardly in the tray opening. For each leg, at least one tray engaging projection is provided on that leg to limit the upward displacement of the cover plate when the upwardly flowing vapor pressure pushes against the cover plate. This defines fluid escape passages between the cover plate and the tray deck.
• At least two perforations are provided and the legs are at positions that lie between the perforations but are spaced outwardly therefrom, on the cover plate.
• the or each bleed fluid deflecting member may be a hump bridge over the fluid opening.
• the or each hump bridge may be a portion of the cover plate which has been formed by providing pairs of parallel slits in the cover plate and upwardly pressing the portion of the cover plate between the slits to provide the perforation there/below leading to the oppositely facing outlets on each side thereof.
• Three perforations with deflecting members may be provided, and in plan view, they may be arranged in a V-formation around the center of the cover plate with the deflecting member hump bridges extending along parallel, spaced paths .
• the cover plate legs may be along paths which extend from the center of the cover plate, between the three deflecting members.
• the or each deflecting member may be a portion of the cover plate which has been formed by providing pairs of parallel slits in the cover plate and upwardly pressing portions of the cover plate on the outer sides of the or each pair of parallel slits to provide the perforations there/below leading to oppositely facing outlets on each side thereof.
• the valve assembly of the present invention provides for a finer dispersion of the lighter fluid over a traditionally inactive area of the valve assembly. This provides for a greater active area than conventional tray assemblies which rely on traditional valve configurations thereby increasing the efficiency of the mass transfer and thus, lowering the energy requirements. More efficient mass transfer allows for a decreased energy requirement for the entire mass transfer exchange system while increasing the efficiency and maintaining the purity of the desired products.
• Figure 1 is a simplified, schematic of a mass transfer exchange column of the present invention showing horizontal tray decks connected to downcomers within the column;
• Figure 2 is an overhead view of a horizontal tray deck
• Figure 3 is a corner view of a conventional, prior art valve device used in the horizontal tray decks
• Figure 4 is an exploded isometric view of a movable valve and tray for providing a valve tray assembly of the mass transfer exchange column of Figure 1;
• Figure 5 is a side view of Figure 4 with the movable valve inserted into in the tray of Figures 1 and 2;
• Figure 6 is a above, top view of the valve assembly of Figures 4 and 5 showing the perforations and deflecting members;
• Figure 7 is a graph showing test results of the efficiency of the assembly shown in Figures 4 and 5 compared to the efficiencies of conventional valve device in Figure 3
• Figures 8 and 9 are graphs showing test results of the entrainment (liquid transported by the gas to the tray above/vapor carrying liquid droplets) of the heavier fluid in the lighter fluid, using the assembly shown in Figures 4 and 5 and conventional valve devices shown in Figure 3;
• Figures 10 and 11 are graphs showing the pressure drop of heavier fluid using, the assembly shown in Figures 4 and 5, and conventional valve devices shown in Figure 3;
• Figure 12 is a corner view of a fixed, fluid dispersing assembly and tray of a mass (transfer) exchange column.
• the term "fluid” is adopted from the terminology of mass transfer applications, in order to describe generally, without restriction to mass transfer technology, the kind of particulates that would flow through the valve of the present invention.
• the particulates in mass transfer operations generally consist of droplets or bubbles at the molecular level or on a microscopic scale.
• vapor or "gas” is a lighter fluid
• liquid is a heavier fluid.
• the dispersion tray valve of the present invention is ideally utilized in a high fluid pressure environment, such as in a trayed tower column. This high fluid pressure environment allows for the separation or fractionation of vapors, gases and liquids.
• tray and "tray deck” refer to the surface within a tower column used in mass transfer applications.
• the tray may also be described as a fluid contacting fractionation tray. In a typical tray installation, the upper surface of the tray is toward the top of the tower and the lower surface of the tray is toward the bottom of the tower. Many different trays may be contained within a trayed or fractionation column.
• tray openings are positioned throughout the tray deck surface. Ordinarily, valves or other devices are positioned above the tray openings to regulate the flow of vapors through the liquids.
• the term tray herein means simply any surface through which a valve, such as in the present invention, is mounted.
• the valve assembly or other device of the present invention may be constructed to fit within the mass transfer fractionation trays.
• the dispersion tray valve is illustrated, described and claimed, generically and in preferred specific embodiments.
• the valve assembly or other device of the present invention is preferably inserted into the openings of the trays for use in a tower column and fluid environment. However, it is not intended to restrict the application of the invention to a valve for use in only a fluid environment or a tower column.
• valve assembly or other device of the present invention preferably moves in an upward and downward motion relative to the tray deck. This movement allows for the fluid to pass from one side of the tray deck to the other side to accomplish the fractionation of fluids required by mass transfer technology.
• the distance between the tray deck and the dispersion valve defines a fluid escape passage or opening where upwardly flowing particles pass through.
• Figures 1 and 2 there is shown, in simple schematics, a vertical oriented tower or column 50 and an above view of a tray deck 1. A number of tray decks 1 are horizontally spaced apart and mounted within column 50.
• Liquid is fed to the uppermost tray deck by a fluid line 61 at an upstream end 56 of the tray deck. Downcomer passages 65 lead down from one tray deck to the next lower tray deck at downstream end 57.
• a lighter fluid or vapor is introduced at the bottom of the tower through feed line 62. As the heavier liquid flows across the tray deck surface 1, the vapor ascends through the openings 10 in the tray to create a bubble or active area 55. In the active area 55, intimate and active contact occurs between the heavier fluid and lighter vapor.
• FIG. 3 shows a prior art valve assembly 70 of conventional construction.
• Valve assembly 70 is mounted in openings 10 of the tray deck 1.
• the valve 70 includes a non-perforated cover plate 71 with legs 73, 73A and 73B to allow the valve to be mounted within tray deck 1.
• a fluids contacting column, tray opening 10, fluid dispersing assembly comprising: a. a bleed fluid perforation, 200, 201 and 202, containing cover plate 21, for the tray opening 10 of tray 1; b. downwardly extending cover plate legs, 23, 23A and 23B, for, in operation, supporting and positioning the cover plate 21 over the tray opening 10 and providing escape passages, such as that designated 110, between the cover plate 21 and the tray deck 1 for fluid 11 flowing upwardly through the opening 10; c.
• bleed fluid deflecting members 224, 225 and 226 contact the lighter fluid streams 200/200A, 221/221A and 222/222A to disperse the fluid streams into finer fluid streams than the fluid stream 110/llOA passing through the fluid escape passages 20.
• the assembly 18 is a valve assembly and the cover plate 21 rests on the tray over the opening 10 thereunder, the legs 23, 23A and 23B are slidable, in and extending downwardly in the tray opening 10, and, for each leg 23, 23A and 23B, at least one tray engaging projection, 230, 230A and 230B respectively, is provided on that leg 23, 23A and 23B for limiting cover plate upward displacement, by upwardly flowing fluid, to reveal the escape passages such as that designated 20.
• three perforations 200, 201 and 202 are provided, and the legs, 23, 23A and 23B, are at positions that lie between the perforations, 200, 201 and 202, but are spaced outwardly therefrom, on the cover plate 21.
• the bleed fluid perforations are arranged in a V-shaped formation such that the fluid streams pass over a traditionally inactive and central area of the valve Z.
• the legs 23, 23A and 23B prevent lateral displacement of the cover plate 21 over the tray 1.
• the valve assembly 18 is made from a material, preferably metal, that will be suitable for the fluids contacting application with which the column (not shown) is intended to be used.
• the valve may be constructed of other materials such as plastics when the valve assembly is to be used in mass transfer applications when the fluids do not interact with the plastic. Valves constructed of plastic lower the cost of the equipment for the column.
• the cover plate 21 is circular, for covering a circular opening 10, and the three legs 23, 23A and 23B, are integral therewith and are circumferentially spaced therearound at 120 degrees from one another to lie along paths which extend from the center of the cover plate 21, between the deflecting members 224, 225 and 226.
• tray engaging projection 230 which is a central tongue portion of leg 23 formed from an inverted, elongated, u-shaped cut portion of the leg 23 which has been bent to extend outwardly therefrom in an upward direction, preferably at an acute angle; and ii) .
• tray engaging projection 230A which is a side tongue portion of leg 23A formed from an inverted, L-shaped cut portion of the leg 23A which has been bent to extend outwardly therefrom, in an upwardly direction, preferably at an acute angle.
• the distance 15 between the upper end of the tray engaging projection 230 and the cover plate 21 determines the maximum height of the escape passage 110 when the cover plate 21 is fully displaced by being floated upwardly by lighter fluid to the position shown in Figure 5.
• the tray opening 10 may be provided with at least one anti-rotation tab, such as that designated 1A, Figure 4.
• the tab la protrudes slightly inwardly, radially from the perimeter of the tray opening 10 so that when leg 23 is in the opening 10 rotation of the cover plate 21 in the opening 10 is restricted. This facilitates a more uniform passage of fluid through all of the escape passages, such as that designated 110, and ensures a more predictable fluid flow rate calculations to be made to achieve higher efficiency.
• Anti-sticking tabs such as that designated 24 in Figures 4, 5 and 6, protrude slightly downwardly form the cover plate 21.
• the tabs 24 ensure that there is always a gap between the underside of the cover plate 21 and the tray 1. This avoids the cover plate 21 becoming completely suction attached to the tray deck 1 during use so that the cover plate 21 may be floated.
• the bleed fluid deflecting members 224, 225 and 226 may be described as hump bridges, sun roof projections or canopies providing bleed fluid openings, such as those designated 22 on opposite sides of the bleed fluid deflecting members 224, 225, and 226.
• the three bleed fluid deflecting members 224, 225 and 226 when viewed from above are in a V-formation around the center of the cover plate 21, and extend upwardly over in and span the perforations 200, 201 and 202 from side-to-side, along parallel, spaced paths, and may be provided by cutting parallel slits in the cover plate 21 and either upwardly pressing the portion of the cover plate 21 between the lists by stamping, or molding, an upwardly curved bridge or canopy to provide the perforations 200, 201 and 202, with the bleed fluid deflecting members 224, 225, and 226 spanning them.
• the tray opening 10 and the cover plate 21 including the perforations 200, 201 and 202 may be other geometric shapes such as round, square or triangular. While three perforations 200, 201 and 202 are provided in this embodiment, the number, size and configuration of the perforations and the bleed fluid openings, such as those designated 22, will be determined by the size of the openings 10 in the tray 1, and the dispersed fluid dispersion effect desired.
• a relatively heavier fluid stream flows over the top of the tray 1, in the direction of arrow X, while a relatively lighter fluid 11 flows upwardly through the opening 10 ( Figure 4) lifting the assembly 1 to reveal the escape passages, such as that designated 10.
• a portion of the lighter fluid 11 passing through the opening 10 escapes as streams of relatively large droplets or bubbles 110 and 110A from the fluid escape passages 20, such as that designated 10, into the heavier stream, while another portion thereof passes upwardly through the perforations 200, 201 and 202 to be deflected by the deflecting members 224, 225 and 226, as two emerging streams of relatively finer bubbles, 220 and 220A into the heavier streams, from the oppositely facing outlets, such as those designated 22 and 22A.
• the streams of finer bubbles 220 and 220 A flow in opposite directions, away from one another, form the outlets, such as those designated 22 and 22A, over the cover plate 21 before ascending through the heavier liquid.
• This flow pattern of the finer bubbles 220 and 220A i) directs finer bubbles 220 and 220A into portions of the heavier fluid in the central zone Z of the cover plate, which would otherwise be stagnant, that is, free of bubbles of lighter fluid of any size, and ii) .
• Provides greater surface area contact between the lighter and heavier fluids, and these two features increase the assembly 18 and tray 1 efficiency thus lowering operation costs by increasing the rate of reaction when compared with conventional assembly and tray designs.
• F represents the square root of kinetic energy of the vapor for a superficial vapor velocity of 0.46 m/s to 2.3 m/s
• E represents the exchange efficiency, that is, as a ration of the change of composition of the tray to the change that would occur on a theoretical tray.
• -•- represents a conventional tray with 8% of the tray surface area perforated and with cover plates containing no perforations.
• - ⁇ - represents the tray of -•- with cover plate perforated
• -o- represents the tray of -•- with the cover plate having perforations and deflecting members as shown in Figures 4 and 5 according to the present invention.
• valve assembly of Figures 4 and 5 offers approximately a 10% increase in efficiency over the conventional tray at the normal operating range of the flows tested.
• the results were obtained with a test column of
• the top tray was used to collect the entrainment which was measured by recording the time elapsed to fill a container.
• the top tray was also covered with a 30-mm layer of mist eliminator mesh to ensure that the entrained water was not carried out of the column.
• the bottom tray was designed as an air distributor and a weeping collector.
• FIGS 10 and 11 show pressure drop comparisons for the water flowing downwardly in the air/water systems of Figures 8 and 9.
• the water pressure drop for the assembly shown in Figures 4 and 5 is approximately 10 to 20% lower than those of conventional valve assemblies of Figure 3, depending on the flow rates of the fluids.
• the assembly as shown in Figures 4 and 5 was found to be able to provide a greater escape over the lighter fluid to pass upwardly through a tray than that of conventional trays .
• a cover plate 121 is attached to the tray 1 by three downwardly extending cover plate legs, two of which are shown and designated 123 and 123A.
• the legs such as 123 and 123A are spaced equidistant from one another around the cover plate 121, and secure the cover plate 121 in a fixed, raised position over opening 10 in the tray 1 to provide escape passages 124 to 126, between the tray 1 and cover plate 121, for upwardly flowing fluid through the opening 10.
• Three bleed fluid perforations 100, 100A and 100B are provided in the cover plate 121, each having a bleed fluid deflecting member 122, 122A and 122B, respectively, spanning that perforation 100, 100A and 100B, to provide oppositely facing outlets, such as, 128 and 128A.
• the cover plate 121, legs such as 123 and 123A, and members 122, 122A and 122B may be integral with the tray deck and pressed therefrom. In other embodiments, the cover plate 121, legs such as 123 and 123A, and members 122, 122A and 122B may be integral, and pressed from sheet, mounted in the tray 1 by springing the legs into the opening 10 until projections (not shown) secure the cover plate 121 at a fixed height over the opening 10.
• the assembly shown in Figure 12 operates in the same manner as that described with reference to Figures 4 and 5, except that the cover plate 121 is fixed in position over the opening 10 and is not lifted by the relatively lighter fluid.
• the perforations with deflecting members may be incorporated into any other configurations of valve cover plates or caps such as square, rectangular, triangular or other shapes as required by the specifications of the tower.
• different shapes and numbers of perforations and deflecting members may be incorporated into various valves.
• the perforations with the deflecting members may be incorporated into various valves .
• the perforations with the deflecting members may be adapted and used with other traditional valve designs such as other floating valves and other fixed valves such as bubble caps to increase the surface area contact between the lighter and heavier fluids and produce finer fluid droplets and bubbles as needed.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Extraction Or Liquid Replacement (AREA)
• Sampling And Sample Adjustment (AREA)

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Citations (8)

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• 1998
  • 1998-09-01 US US09/145,187 patent/US6145816A/en not_active Expired - Lifetime
  • 1998-10-09 DE DE69817762T patent/DE69817762T2/de not_active Expired - Fee Related
  • 1998-10-09 JP JP52248899A patent/JP2001505823A/ja not_active Ceased
  • 1998-10-09 EP EP98951030A patent/EP0951344B1/en not_active Expired - Lifetime
  • 1998-10-09 CA CA002274697A patent/CA2274697C/en not_active Expired - Fee Related
  • 1998-10-09 WO PCT/US1998/021394 patent/WO1999019054A1/en not_active Ceased
  • 1998-10-09 AT AT98951030T patent/ATE248641T1/de not_active IP Right Cessation
  • 1998-10-09 ES ES98951030T patent/ES2206998T3/es not_active Expired - Lifetime
  • 1998-10-09 CN CN98802384A patent/CN1104941C/zh not_active Expired - Fee Related
  • 1998-10-09 KR KR10-1999-7005187A patent/KR100504992B1/ko not_active Expired - Lifetime
• 2000
  • 2000-02-15 US US09/504,291 patent/US6270062B1/en not_active Expired - Lifetime

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