MXPA99003901A - Downcomer for chemical process tower - Google Patents

Abstract

A chemical process tower tray construction incorporating a tapered semiconical downcomer (120) adaptive for discharging liquid along an arcuate edge portion of an underlying tray (130). The underlying tray (130) is of the type supported within the chemical process tower by support ring (98) which is positioned beneath the edge of the tray for the support thereof. The solid support ring (98) typically forms a nonactive area beneath this region of the tray and the tapered downcomer discharges liquid directly onto the inactive region wherein the remaining portion of the tray can be utilized for mass transfer.

Description

Drop tube for a chemical process tower Field of the Invention The present invention relates to chemical process towers and, more particularly, but in a limiting manner, to a drop tube assembly with gradual reduction to maximize the development of the mass transfer through the adjacent plate.

Background of the Invention The distillation columns are used to separate selected compounds from a multicomponent stream. Successful fractionation in the column depends on the intimate contact between the liquid and vapor phases. Some columns use devices for vapor or liquid contact such as dishes.

REF .: 30031 The dishes referred to above are generally installed on support rings within the tower have a plate or a solid cover with a plurality of openings in an "active" area. The liquid is directed on the plate by means of a vertical channel from the previous plate. This channel is referred to as the descent tube. The liquid moves through the active area and exits through a similar descent tube. The location of the descent tubes determines the flow pattern of the liquid. The steam rises through the openings in the plates and is in contact with the liquid that moves through the plate. The liquid and steam are mixed in the active area and fractionation occurs. The active area of the plate is a critical point.

The maximum capacity of fractionation of the plate increases generally with the increase of the active or bubbling area. The maximum utilization of the active area of a plate is an important consideration for the design of a tower of chemical processes. Dish regions that are not effectively used for vapor-liquid contact can reduce fractionation capacity and plate efficiency. Therefore, there is a need for an apparatus and methods that optimize the design of the active area of a fractionation plate in a chemical process tower.

It is well known that the difference in concentration between vapor and liquid is the force that makes mass transfer possible. This difference in concentrations can be affected in different ways; some reduce the fractionation efficiency. When the operating pressure is such that it produces a vapor density close to 1.0 lb / cu ft, there is a possibility that a certain amount of vapor bubbles will combine or become trapped with the liquid entering the descent tube . For example, while the operating pressure increases due to an increase in vapor concentration, the descending liquid begins to absorb steam as it moves through the plate. This is usually associated with the dissolved gas governed by Henry's law and represents much larger amounts of vapor bubbles that combine or "trap" with the liquid. This vapor is not carried firmly and is released into the drop tube, and, in fact, most of said steam must be released, otherwise the drop tube can not accommodate the liquid / vapor mixture and will flood this prevents the successful operation of the tower.

Similarly, an exothermic reaction in the drop tube will generate vapors of the equilibrium mixture, which will also be released. For conventional dishes, the steam released will oppose the frontal descent of the vapor / liquid mixture that flows into the descent tube. In different cases, this opposition causes a low tower operation and a premature nullification. Therefore, there is a need for an apparatus and methods that facilitate the release of vapor trapped in the liquid within a descent tube of a chemical process tower.

Another serious problem which is self-evident in the operational applications is the dragging of drops of liquid in the ascending vapor. This phenomenon, which is virtually the opposite of vapor creep, can prevent the effective contact with liquid vapor. The liquid dragged is, in a sense, a condition of dynamic flow. The high velocity of the steam flow can suspend the descent of the liquid droplets and prevent their effective passage through the underlying zone of the foam mixture. It is particularly difficult to prevent this problem when the applications of the tower require large volumetric flows of steam in a direction virtually opposite to the large volumetric flow of descending liquid. Therefore, there is a need for apparatus and methods that reduce the entrainment of liquid in the steam within a tower of chemical processes.

The efficiency of a dish is also reduced when the steam that rises through the process column is allowed to deviate from the active area of a dish. An area where steam can deviate from the active area of a. lato is the descent tube. When the steam is projected by the active area of a dish it does not intentionally pass through the down tube, it will reduce the flow of liquid through the down tube, it will reduce the efficiency of the active area in the dish. Also, the unintentional passage of steam through the down tube will reduce the flow of liquid through the down tube and potentially cause an accumulation of the liquid flowing through the process column. Therefore, there is a need for apparatus and methods that reduce the amount of steam flowing through a down tube.

The efficiency of an active area in a dish is also influenced by the flow of the liquid through the active area. At the initial point of contact of the liquid from a descent tube on the dish, the flow of the liquid is typically not a flow characteristic that provides the optimum efficiency of the active area of a dish. Therefore, there is a need for apparatus and methods that assist in changing the flow characteristics of the fluid from a descent tube over the active area of a dish. The present invention provides a method and apparatus for maximizing the efficiency of mass transfer in chemical process towers.

Brief Summary of the Invention The present invention relates to the configuration of a descent tube in a plate of a tower of chemical processes. more particularly, one aspect of the present invention comprises a drop tube with gradual reduction placed near a plate of the chemical process tower. The plate is supported by a support ring and the drop tube has a gradual reduction to discharge the liquid directly on the plate region directly on the support ring. A dam is provided in a generally curved manner on the plate in the region of the periphery of the support ring to define the entrance area of the plate and which controls the discharge of the liquid from it onto the plate.

In another aspect, the present invention includes a tower, a descent tube, and a dish. The tower has at least one support plate. The descent tube has an outlet for liquid flow from it and is placed inside the tower near the plate holder. The plate is supported on the plate support inside the tower and under the support tube. The plate has a plate support region placed near the support ring of the tower plate. The plate also has an internal area of the plate located in an area to receive liquid from the outlet of the down tube. The support of the tower plate and the outlet of the drop tube are positioned such that the entrance area of the plate is substantially within the support area of the plate.

In another embodiment, the present invention comprises an improved method for mixing gas with a liquid in a drop tube in a process tower using a plate, the improvements comprising the steps of supporting the plate in the process column with a plate holder located under a support area of the plate, and placing the drop tube such that the liquid of the drop tube flows over an inlet area of the plate that is substantially within the support region of the plate where the fluid from the outlet of the tube of descent is in contact with the plate.

In another embodiment, the present invention comprises a process column comprising a tower, a drop tube placed inside the tower and having an outlet for the flow of liquid therefrom, and a dish placed inside the tower below the tube of descent. The plate includes an inlet dam that surrounds the entrance region of the descent tube where the fluid from the outlet of the descent tube is in contact with the plate.

In another embodiment, the present invention comprises mounting an improved dish for use in a process column of the type where the liquid from a drop tube passes over the dish to join a gas rising through the column, the improvement comprises of a dam in the entrance that surrounds an entrance area of the descent tube of the dish where the liquid of said descent tube is in contact with the dish.

Brief description of the Drawings For a more complete understanding of the present invention and for other objects and advantages thereof, the reference may not have had to follow the description taken in conjunction with the accompanying drawings in which: FIG. 1 is a perspective view of a column packed with several sections of separate cuts to illustrate a variety of internal parts of the tower and one embodiment of a mounting of the drop tube and the dish constructed in accordance with the principles of the present invention found herein; FIG. 2 is a perspective, enlarged, fragmented view of a mounting of the drop tube and the plate of FIG. 1, with portions of cuts separated from the tower and illustrating the construction of the drop tube and the dish of the present invention; FIG. 3 is a perspective view, enlarged, fragmented of a mounting of the drop tube and the plate of FIG. 2, taken from inside the tower; FIG. 4 is a cross-sectional, elevated, diagrammatic view of an assembly of the drop tube and the plate of FIGS. 2 and 3 that illustrate the operating principles of this; 'FIG. 5A is an enlarged fragmentary top view of one embodiment of the mounting of the drop tube and the plate of FIGS. 2 and 3; FIG. 5B is an enlarged fragmentary top view of another embodiment of the down tube assembly and the plate of FIGS. 2 and 3; Y FIG. 5C is an enlarged fragmentary top view of another embodiment of the down tube assembly and the plate of FIGS. 2 and 3.

Detailed description of the invention Referring to FIG. 1, here is a perspective, fragmented view of an illustrative packaged ion exchange tower or column with several separate cutting sections to show a variety of internal parts of the tower and the use of an improved mounting mode of the down tube the present invention. The exchange column 10 of FIG. 1 comprises a cylindrical tower 12 having packed beds 38 and 39, and the mounting of the lowering tube and the plate 100 incorporating the principles of the present invention set forth herein. The tower 12 of the column 10 includes a skirt 28 for the support of the tower 12. A plurality of man inputs 16 are constructed to facilitate access to the internal region of the tower 12. A line feeding line is provided. of steam or return line of the reboiler 32 in the lower part of the tower 12 and an outlet or upper line 26 is provided in an upper portion of the tower 12. A return line of the reflux 34 is provided in an upper portion of the tower 12 and an outlet line of the bottoms stream 30 at the bottom of tower 12. An outlet line of lateral stream 20 and a lateral liquid supply line 18 are also provided in tower 12.

Even referring to FIG. 1, in operation, steam 15 is fed into the tower 12 through the return line 32 and liquid 13 is fed into the tower 12 through the reflux return line 34 and the inlet feed line of the side stream 18. Steam 15 flows up through column 10 and finally leaves tower 12 through steam outlet 26. Liquid 13 flows down through column 10 and finally leaves tower 12 through separation of the lateral stream 20, or in the line of separation of the bottom current 30. In this downward flow, the liquid 13 is exhausted from some material which is gained by the vapor 15 while it passes through the assembly of the plate 100 and packed beds 38, 39 of column 10, and steam 15 is depleted of some material which is gained by liquid 13.

Referring still to FIG. 1, it can be seen that the upper packed bed 38 is of a structured packing variety. Shown are for purposes of illustration the regions of the exchange column 10 below the upper packing 38 and include a liquid collector 40 positioned below a support grid 41 in support of the upper structured packing 38. A liquid distributor 42, adapted to redistribute the liquid 33 is placed in the same way here below. A second type of manifold 42a is shown below the cut line and is positioned near the lower packed bed 39. The internal array of column 10 is a single diagram representation and different arrays of compounds are provided here.

Referring now to FIGS. 2 and 3, here are two fragmented perspective views of the mounting of the drop tube and the plate 100 in FIG. 1 shots from opposite angles relative to the tower 12. In this embodiment, the mounting of the drop tube and the plate 100 includes a first plate 110 connected to a first drop tube 120, and a second plate 130 connected to a second tube of descent 140. Plates 110 and 130 are generally flat panels having central active areas 111 and 131, respectively. Plates 110 and 130 are supported by support rings 98 and 99, respectively of tower 12. Obstructions are placed at exit 112 and 132 of a first and second platens, respectively, adjacent to descent tubes 120 and 140, respectively . The obstructions of the outlet 112 and 132 are preferably a plate or an ascending strip welded to the flat panels of the plates 120 and 140.

Even referring to FIGS. 2 and 3, the descent tubes 120 and 140 have semi-conical walls 121 and 141, respectively, having gradual reduction from the exit obstructions 112 and 132 of the plates 110 and 130, downward toward the inner surface of the tower 12. walls 121 and 141 of the descent tubes 120 and 140 are preferably formed of flat plates 121a-d and 141a-d, respectively, which are welded together in a configuration shown here. The current construction of the drop tube may vary in accordance with the principles of the present invention. For example, the segmented angle construction of the side walls of the drop tube may be modified with most sections of drop tube or a few sections of the drop tube and a curved or bent construction. The outlets of the descent tubes 122 and 142 are placed directly 122 and 142 are formed between the bottom of the walls 121 and 141 and the inner surface of the tower 12. In one embodiment, the exits of the descent tube 122 and 142 are placed directly above the plate support rings 98 and 99 of the tower 12 and have an open area that is substantially contained within the area directly above the support rings 98 and 99.

Referring even to FIGS. 2 and 3, the plate 130 has an internal obstacle 133 positioned around the area directly below the outlet of the drop tube 122. The internal obstacle 133 is preferably a vertical strip or plate welded to the flat panel of the plate 130. In one embodiment, the internal obstacle 133 has a vertical height that extends upwards from the position of the outlet of the drop tube 122. The lower portion of the drop tube 120 is supported by supports 134 which are welded to the inner dam 133 and bolted to the lower portion of the down tube 130.

Referring even to FIGS. 2 and 3, the platen 130 includes a plurality of venting chambers 135 that are positioned in an area of the platen 130 positioned on the opposite side of the entrance dam 133 of the outlet of the drop tube 122. The venting chambers 135 have a plurality of openings 135a to use the steam 15 to impart a horizontal flow to the liquid 13 leaving the entrance dam 133.

Referring now to FIG. 4, the liquid 13 crosses the active area 111 of the plate 110 that finds the vapor 15 that ascends through the active area 111. The exit dam 112 controls the flow of the liquid 13 that passes from the active area 111 of the plate 110 into the drop tube 120. The liquid 13 flows over the outlet dam 112 of the plate 110 passes down between the wall 121 of the down tube 120 through the outlet 122 and accumulates on the plate 130 in an area between the internal dam 133, and the inner wall of tower 12.

Even referring to FIG. 4, once the. level of the liquid 13 that accumulates in the area of the plate 130 between the inner wall of the tower 12 and the internal dam 133 reaches the height of the internal dam 133, the additional liquid 13 leaving the outlet of the descent tube 122 will cause that the liquid 13 passes or leaves the entrance dam 133. The vapor 15 of the vent chambers 135 imparts a horizontal vector flow to the liquid 13 that leaves the entrance dam 133 through the active area 131 of the dish 130. liquid 13 passing over the active area 131 of the dish 130 which finds steam 15 which rises through the active area 131.

Referring still to FIG. 4, the encounter of the liquid 13 passing through the active area 131 of the plate 130 with the vapor 15 rising through the active area 131 creates the foam 61. As previously stated, foaming or "foam" is a region of aeration where the liquid phase 13 is continuous. The foam 61 extends with a relatively uniform height, shown in phantom by the line 63, through the active area 131 of the plate 130. The height of the active area 131 of the plate 130 is governed by the distance between the entrance dam 133 and the exit dam 132. The exit dam 132 also controls the flow of foam 61 or liquid 13 that passes from the active area 131 of the dish 130 into the downflow tube 140, when the fluid leaves the dish 130 to the next process in column 10 Referring now to FIG. 5A, a top view of the plate 110 and the drop tube 120 illustrated in FIGS. 2, 3 and 4. The drop tube 120 is separated from the active area 111 of the dish 110 by the exit dam 112. In the embodiment illustrated in FIG. 5A, the drop tube 120 is a string-shaped drop tube characterized by the linear exit dam 112 of the platter 110 which defines the end of the dish 110 in the manner of a string.

Referring now to FIG. 5B, a top view of another embodiment of the plate 110 and the drop tube 120 of FIGS. 2, 3 and 4. In the embodiment illustrated in FIG. 5B, the drop tube 120r is the curved drop tube (or multi-string drop tube) and is characterized by the outlet dam 112 'having different segments. The outlet dam 112 'has first and second segments 112a' and 112b ', which are arranged in the manner of a collinear rope. A third section 112c 'is parallel to the first and second sections 112a' and 112b ', but are placed centrally between the first and second sections 112a' and 112b ', and is fixed towards the tower 12. The fourth and fifth sections 112d 'and 112e' of the exit dam 112 'connects the third section 112c' with the first section 112a 'and the second section 112b', respectively.

Referring now to FIG. 5C, a top view of another embodiment of the plate 110 and the drop tube 120 illustrated in FIGS. 2, 3 and 4. In the embodiment illustrated in FIG. 5C, the descent tube 120 is defined by the outlet dam 112. The exit dam 112"is characterized by the curved section which is semicircular extending towards the descent tube 120.

Referring now to FIGS. 2, 3, 4 and 5A-C in combination, the outlet of the drop tube 122 is narrower than the upper »region of the drop tube 120, causing an accumulation in the region of the tube outlet of descent 120. The accumulation of the liquid 13 in the region of the outlet of the descent tube 122 causes a dynamic seal which prevents the vapor 15 from ascending through the column 10 to pass through the descent tube 120 instead of the platen 110. A seal is also created by the relatively vertical height of the outlet 122 of the descent tube 120 and the entrance dam 133 of the platen 130. A liquid pool 13 of the descent tube 120 was created between the entry dam 133 and the inner wall of the tower 12. When the vertical height of the outlet 122 of the drop tube 120 is located near or below the vertical height of the entrance dam 133 of the plate 130, the outlet 122 will be immersed in the pond of the liquid accumulated between the entrance dam 133 and the internal surface of the tower 12. Because the outlet 122 of the descent tube 120 is at or below the level of a pool of accumulated liquid between the inlet dam 133 of the plate 130 and the inner surface of the tower 12, the vapor 15 rising through the column 10 will inhibit the flow through the down tube 120 and the passage through the plate 110.

Even referring to FIGS. 2, 3, 4 and 5A-C, the plate 130 has a region of the support ring 137 on the upper side 130a of the plate 130 directly above the location where the support ring 98 meets the plate 130. Due to the structural constraint, the support ring region 137 of conventional support rings can not ordinarily be used as an active area for the mixing of liquid 13 and vapor 15. (This aspect focuses on US Patent No. 5,547,617 assigned to the assigned of the present invention). The plate 130 also has an entrance area of the plate 138 located in the position on top side 130a of the plate 130 where the liquid 13 of the outlet of the drop tube 122 first comes into contact with the plate 130. Because the flow of liquid 13 from the outlet of the down tube 122, the inlet area 138 of the dish 130 can not easily be used as an active area for the mixing of the liquid 13 and steam 15. Because the outlet of the down tube 122 has an area contained above the plate support ring 98, the entrance area of the plate 138 is substantially within the region of the support ring 137 of the plate 130. By consolidating the entrance area of the plate 138 of the plate 130 substantially within the region of the support ring 137, the area of the plate 130 suitable for use as active area 131 is increased over conventional dish assemblies that do not place the entrance area of the dish substantially within the s support in the region of the plate 130 or otherwise. this publication is focused Even referring to FIGS. 2, 3, 4, and 5A-C, because of the support ring 98 is a narrow band around the inner circumference of the tower 12, the region of the support ring 137 of the plate 130 will be along the narrow region. In order for the entrance arch of the plate 138 to be substantially within the region of the support ring 137, the outlet of the drop tube 122 will usually need to be larger than the conventional drop tubes to accommodate the liquid 13 flowing through of the drop tube 120. However, as shown here, the length of the outlet of the drop tube 122 and the internal area of the corresponding plate 138 of the plate 130 can vary significantly within the region of the support ring of the plate 137 of the dish 130 without having any effect on the availability of the active area 131 internally of the region of the support ring 137.

It is thus believed that the operation and construction of the present invention will be apparent from the foregoing description. While the method and apparatus shown or described have been characterized as preferred it will be obvious that different changes and modifications can be made here without departing from the scope and perspective of the invention as defined in the following claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (26)

Claims

1. A process column, characterized in that it comprises: a tower having at least one supporting ring of the dish mounted therein; a plate supported on the plate support ring inside said tower, said plate has a region of support of the plate directly above the location where the support ring of the plate joins said plate; and a descent tube having a semicircular outlet for the flow of the liquid therethrough, said semicircular outlet having an internal substantially semicircular wall and positioned substantially above, and directed towards the support region of said dish, said descent tube it has a semi-circular wall that has a gradual reduction towards the substantially semicircular wall of the semicircular outlet.

2. The column of processes as set forth in claim 1, characterized in that said plate includes an entrance area of the plate where the liquid of said descent tube encounters said plate and an entrance dam placed on the upper surface of said plate encloses the area of the entrance of the dish.

3. The column of processes as set forth in claim 2, characterized in that the entrance dam of said plate includes an upper edge and where the semicircular outlet of said lower tube is placed below the upper edge of the entrance dam of said plate .

4. The column of processes as set forth in claim 2, characterized in that said plate includes an active area and at least one venting chamber for the passage of vapor such that said vapor exerts a force against the liquid of the entrance dam through the active area.

5. The column of processes as set forth in claim 1, characterized in that it also includes a top plate having an outlet dam, said top plate is positioned such that the fluid passes over the outlet dam flowing into the down tube.

6. The column of processes comp was set out in claim 5, characterized in that the outlet dam of said upper plate is an exit dam in the form of a rope.

7. The column of processes as set out in claim 5, characterized in that the outlet dam of said upper plate is a multi-sectioned exit dam.

8. The column of processes as set out in claim 5, characterized in that the outlet dam of said upper plate is an arched exit dam.

9. The process column as set forth in claim 8, characterized in that the arched exit dam is a semicircular outlet dam.

10. The column of processes as set forth in claim 5, characterized in that said plate includes an entrance area of the plate where the liquid of said descent tube meets said plate and an entrance dam placed on an upper surface of said plate surrounds the entrance area of the plate.

11. The column of processes as set forth in claim 10, characterized in that the entrance dam of said plate includes an upper edge and where the semicircular outlet of said down tube is placed below the upper edge of the entrance dam of said plate .

12. The column of processes as set forth in claim 10, characterized in that said plate includes an active area and at least one ventilation chamber for the passage of vapor such that said vapor exerts a force against the liquid from the entrance dam through the active area.

13. A method for forming a tower of chemical processes, characterized in that it comprises the steps of: mounting a dish support ring inside the chemical process tower; form a dish; supporting the plate on the plate support ring in the chemical process tower with a plate support region directly above the plate support ring; forming a descent tube with a semicircular descent tube outlet having a substantially semicircular internal wall and a semiconic shape that is gradually reduced towards the substantially semicircular internal wall of the semicircular descent tube outlet; and placing the outlet of the semicircular descent tube substantially over the plate support region and directing the exit of the semicircular descent tube substantially toward the plate support region to define a plate entry area substantially within the region of the plate. dish support.

14. The method set forth in claim 13, characterized in that it also includes the step of forming an entry dam on it. dish that surrounds the entrance area of the dish.

15. The method set forth in claim 14, characterized in that the step of forming an inlet dam includes forming the inlet dam with an upper edge, and where the step of placing the outlet of the semicircular descent tube includes placing the outlet of the down tube semicircular below the upper edge of the entrance dam on the plate.

16. The method set forth in claim 14, characterized in that the step of forming the inlet dam includes forming the inlet dam with an upper edge above the outlet of the semicircular descent tube.

17. The method set forth in claim 14, characterized in that the step of forming the plate includes forming the plate with an active area and further includes the step of forming at least one venting chamber on the plate for vapor passage such that steam exerts a force against the liquid from the entrance dam through the active area of the plate.

18. The method set forth in claim 13, characterized in that it further includes the steps of: forming a top plate with an outlet dam; and placing the upper plate such that the fluid passes over the outlet dam flowing into the down tube.

19. The method set forth in claim 18, characterized in that the step of forming the upper plate includes forming the upper plate with the exit dam that has the shape of a rope.

20. The method set forth in claim 18, characterized in that the step of forming the upper plate includes forming the upper plate with the exit dam that has the shape of a ball.

21. The method set forth in claim 18, characterized in that the step of forming the upper plate includes forming the upper plate with the outlet dam having an arcuate shape.

22. The method set forth in claim 21, characterized in that the arched shape of the exit dam is semicircular.

23. The method set forth in claim 18, characterized in that it also includes the step of forming an entrance dam on the plate that surrounds the entrance area of the plate.

24. The method set forth in claim 23, characterized in that the step of forming the entry dam includes forming the entry dam with an upper edge and where the step of placing the exit of the semicircular descent tube includes placing the outlet of the drop tube semicircular below the upper edge of the entrance dam on the plate.

25. The method set forth in claim 23, characterized in that the step of forming the inlet dam includes forming the inlet dam with an upper edge above the outlet of the semicircular descent tube.

26. The method set forth in claim 23, characterized in that the step of forming the plate includes forming the plate with an active area and further includes the step of forming at least one venting chamber on the plate for vapor passage such that the steam exerts a force against the liquid from the entrance dam through the active area of the plate.