CA1333470C - Packing for a mass and heat exchange column - Google Patents
Packing for a mass and heat exchange columnInfo
- Publication number
- CA1333470C CA1333470C CA000607954A CA607954A CA1333470C CA 1333470 C CA1333470 C CA 1333470C CA 000607954 A CA000607954 A CA 000607954A CA 607954 A CA607954 A CA 607954A CA 1333470 C CA1333470 C CA 1333470C
- Authority
- CA
- Canada
- Prior art keywords
- packing
- uppermost layer
- liquid distributor
- elements
- packing elements
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/30—Loose or shaped packing elements, e.g. Raschig rings or Berl saddles, for pouring into the apparatus for mass or heat transfer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/30—Details relating to random packing elements
- B01J2219/302—Basic shape of the elements
- B01J2219/30215—Toroid or ring
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/30—Details relating to random packing elements
- B01J2219/304—Composition or microstructure of the elements
- B01J2219/30408—Metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/30—Details relating to random packing elements
- B01J2219/304—Composition or microstructure of the elements
- B01J2219/30416—Ceramic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/30—Details relating to random packing elements
- B01J2219/304—Composition or microstructure of the elements
- B01J2219/30433—Glass
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/30—Details relating to random packing elements
- B01J2219/304—Composition or microstructure of the elements
- B01J2219/30466—Plastics
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physical Or Chemical Processes And Apparatus (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
Abstract
The invention relates to a packing (2) for a mass and heat exchange column (1) in which a gaseous and a liquid phase are brought into contact with one another, and comprising a large number of identical packing elements (4) having essentially the shape of a circular hollow cylinder whose wall (6) is circumferentially concave towards the outside and convex towards the inside, forming two outer, circumferential rims (11), and having a large ratio of outer diameter (D) to height (H). In order to keep the pressure loss to a minimum and to increase capacity and effectiveness, provision is made for the packing (2) to consist of a large number of superimposed layers (3) of flat-lying packing elements (4), randomly distributed in each layer (3) and having internally an open cross section, also possessing a ratio of outer diameter (D) to height (H) of about 6:1 up about 10: 1.
Description
Packing for a mass and heat exchange column The invention relates to a packing for a mass and heat exchange column in which a gaseous and liquid phase are brought into contact with one another, and comprising a large number of identical packing elements having essentially the shape of a circular hollow cylinder whose wall is circumferentially concave to the outside and convex to the inside, with two outer circumferential rims, and exhibiting a large ratio of outer diameter to height.
In mass and heat exchange columns in which a gaseous phase is brought into contact with a liquid phase, a transfer of mass and heat takes place; for example, absorption occurs as a component makes the transition from the gaseous into the liquid phase, or desorption occurs when a component makes the transition in the opposite direction, or rectification occurs when the transition of components takes place in both directions. Since as a rule temperature differences exist, a transfer of heat also simultaneously takes place, and this is why mass exchange columns are always at the same time heat exchange columns as well. As a rule, the gaseous phase is allowed to flow through the column counter-current to the liquid phase; only in rare cases is the co-current flow principle employed (while cross-current flow is considered only for cooling towers in which heat exchange takes place). The columns are provided with filler elements whose task it is to ensure a high exchange performance (efficiency) between the gaseous and the liquid phase, also a high throughput (capacity) for both phases and the lowest possible pressure loss.
Filler elements for mass and heat exchange columns may take the form of unordered as well as ordered packings.
Ordered packings consist preferably of coarsely folded lamellae arranged with their crests crossing at an angle to each other and to the column axis, and also provided with a fine structure in the form of grooves and holes, or similar. It is a relatively complicated matter to manufacture and arrange these packings in the column.
- 13334~l~
Unordered packings consist of individual packing elements which are simply poured into the columns. Compared with ordered packings, it is therefore a much simpler matter to arrange these packings in the column. Such packing elements include the Raschig rings, which have been known for a long time and which possess a ratio of about 1:1 between their diameter and height. A further refinement of these structures are the Pall rings, which possess small tongues extending inwards and leaving corresponding holes in the rings, thereby considerably boosting capacity. Dead zones have been reduced in the Pall rings by reducing the ratio between diameter and height to 3:1, by leaving out a row of tongues.
A similar development has also taken place in the case of roof-shaped, semi-cylindrical, saddle-shaped, or similarly shaped packing elements which are also poured in random manner into the column and which are provided with increasingly complicated surface configurations in the form of holes, ribs, grooves, projections, depressions, tongues, etc.
Due to their structural characteristics, unordered packings exhibit a relatively high pressure loss in the axial direction of the column which impairs the capacity of the packing and the effectiveness of the mass exchange.
This is also true of packings which are manufactured from packing elements of the kind described in DE-A-2 164 144.
These packing elements may be circularly cylindrical in shape, with possi~ly a concave outer surface and with inward-pointing ribs, which may also project axially relative to the cylindrical section. The ribs are intended to prevent the packing elements from becoming wedged inside one another when they are poured into the column, and the drop in pressure which would be caused by this partial alignment of the packing elements is, as a result, reduced. It is a compli~ated matter to provide these ribs, at least in the case of packing elements made of cold-formed metal, and when the packing elements are poured into a column they do not arrange themselves in a well-ordered structure, but instead the packing structure is random and unordered, and it contains not only flat-lying, but also obliquely and vertically oriented 1333k7~
packing elements which still cause a relative high loss of pressure.
It is an object of the invention to provide a packing of the kind mentioned at the beginning, which results in a reduced pressure loss and increased capacity and effectiveness of the mass exchange.
This problem is solved by producing the packing from a large number of layers arranged one on top of the other, each layer containing flat-lying, randomly distributed packing elements each having a free cross sectional opening and with a ratio of external diameter to height of about 6:1 to about 10:1.
The packing elements used consist of a ring, similar to a bicycle wheel rim, with a relatively high ratio of diameter to height, so that in a free fall onto a flat substrate, the packing elements assume a flat-lying position in which they rest on a circumferential edge. The probability that at the end of the fall they will come to rest in a vertical position is extremely slight, because this position is an unstable state of balance which would be eliminated by the slightest vibration, or similar, for example the impact of further falling packing elements. As a result, it is possible, by gradually pouring packing elements into a column and distributing them therein, to build up a packing consisting of successive layers of flat-lying packing elements; such a packing is, so to speak, ordered in the axial direction of the column, while the packing elements in each layer are randomly distributed in an unordered manner and each packing element is practically always offset in relation to the immediately adjacent element above or below. In a packing of this kind, the pressure loss is considerably reduced relative to a completely disordered packing, thus permitting considerable improvements in the capacity and effectiveness of the mass exchange. For the same capacity and effectiveness, the volume and thus the weight of the packing are reduced.
In addition, the packing can be built up from packing elements which are very easy to manufacture and also require relatively little effort to install when the column is being filled.
Further features and advantages of the invention are contained in the following description and in the sub-claims.
The invention is described in more detail below on the basis of the embodiments depicted in the attached Figures.
Fig. 1 shows a section of a packing in a mass and heat exchange column; the rings are shown offset in the plane of the drawing while, for reasons of clarity, rings which have been cut through are not shown.
Fig. 2 shows a top view of a section of the packing seen in Fig. 1.
Fig. 3 shows a possible design of a packing element for the packing in Fig. 1.
In accordance with Fig. 1, a column 1 contains a packing 2 supported on an appropriate base (not shown) and consisting of superimposed layers 3 of packing elements 4. A
liquid distributor 5 is located above the packing 2.
The packing elements 4 have the shape of an annular hollow cylinder, and the wall 6 of the hollow cylinder is of essentially uniform thickness and is provided circumferentially with a concave outer side 7 and a convex inner side 8. In addition, the ratio of the outer diameter D to the height H of the hollow cylinder is so large that when they are poured into a column 1, the packing elements 4 assume a flat-lying position on the floor of the column or on a layer of identical packing elements 4. The ratio of the outer diameter D to the height H of the hollow cylinder is preferably between 6:1 and 10:1.
By carefully filling such packing elements 4 into a column 1, and allowing them to spread out in the column, a packing 2 of superimposed layers 3 of flat-lying packing elements 4 is built up. A packing 2 of this kind exhibits an irregular arrangement of the packing elements 4 in each layer 3, with more or less large spaces being left between the individual packing elements 4, although individual packing elements 4 are also in contact with each other at certain points; however, the packing 2 is ordered in the direction of the column axis.
This means that the aerodynamic resistance is reduced compared with that of a totally unordered packing and thus the 1~3347~
drop in pressure within the column 1 is reduced. Because of the partially ordered packing which can be achieved with the packing elements 4, these packing elements 4 also take up less space for the same specific surface area, i.e. the packing factor is reduced or the capacity of the packing 2 can be substantially increased for the same packing volume.
The concave wall 6 of the packing element 4 provides the latter with sufficient strength and also serves to ensure that a packing element 4 can practically never become jammed obliquely or vertically in a horizontal packing element 4, thus preventing the formation of layers 3 at least in certain sections of the packing; but instead, in such a position the packing element would be in an unstable state of equilibrium and therefore, as further packing elements 4 spread out or fall in the column, it would tip over into the horizontal position because of the unstable state of equilibrium.
Advantageously the wall 6 has a circular, and especially a semi-circular, cross section but partially oval concavities are also, for example, possible.
The concave wall 6 also achieves a corresponding increase in surface area, which reduces the pressure loss and increases the effectiveness and the capacity.
The concave wall 6 also means that the liquid phase flows out without any liquid accumulating, so the dwell time of the liquid phase in the packing 2 is correspondingly short. As a result, polymerizations in substances which tend to polymerize can be avoided in the column 1. In addition, the liquid phase does not hold back any solids held in suspension or entrained in any other way.
In a packing 2 according to Fig. 1, the gaseous phase always flows from top to bottom in the axial direction of the column 1 and thus essentially in the axial direction of the individual packing elements 4, and these create a pressure difference between the area adjacent to the outer side 7 and the area adjacent to the inner side 8, and the static pressure pl at the outer side 7 is greater than the static pressure p2 at the inner side 8 tsimilar to the pressure conditions around the wing 1333~70 of an aircraft). This means that a negative pressure exists inside each individual packing element 4, having internally an open cross section, without any inwards projecting ribs, or similar built-in elements. This gives rise to intense gas turbulences and thus to corresponding cross mixing of the gaseous phase, particularly since each individual packing element 4 is slightly offset relative to the adjacent elements in the layers above and below.
Since the liquid phase runs at least partially along the lower edge of the packing element 4, until it comes into contact with the upper edge of a subjacent packing element 4, this causes a mixing of the downward-flowing liquid phase in the direction transverse to the column axis. In this way, an essentially h~mogeneous composition of the liquid phase over the column cross section is achieved.
The cross mixing of the gaseous and liquid phases means that optimum use can be made of the driving temperature and/or concentration gradient.
Precise horizontal adjustment of the packing 2 or of the packing elements 4 is not necessary; a slight inclination leads to a corresponding outflow of the liquid phase.
The thickness of the wall 6 may, for example, be between about 0.2 and 5.0 mm, while the outer diameters D are usually selected in the range from 10 to 300 mm. The minimum ratio that can be selected between column diameter and packing element diameter, without suffering any loss of effectiveness, is about 4.6:1, compared with a minimum ratio of 8 to 12:1 in the case of customary unordered packings so that, in particular in laboratory equipment, packing elements 4 having relatively large diameters D can be used without any disadvantage.
In the case of packing elements 4 having a smaller diameter D, it is observed that these can sometimes come to rest vertically or at an oblique angle against the walls of the column. This is advantageous in columns 1 having a small column diameter in which normally a large amount of liquid flows down the wall of the column, because the liquid is deflected away from the wall into the interior of the column. For this purpose, it is 133~470 also possible to set up packing elements 4 correspondingly along the wall of the column, as shown in Fig. 1.
The packing elements 4 may be made of a variety of materials, for example metal such as carbon steel, stainless steel, titanium, copper, brass, aluminium, etc., which can ideally be cold formed; or they can be made from thermoplastic material such as polypropylene, polyvinyl chloride, polyethylene or similar; ceramic material, rubber or glass may also be used.
The starting material used in the manufacturing process can be provided before, during or after manufacture with a coarse structure, e.g. by forming gas flow openings 9 (Fig. 3), or similar, over which the liquid phase does not normally flow, or similar, and/or they can be given a fine structure in the form of grooves, elevations, depressions, small holes, or similar. The forming of these structures depends on the way in which the packing elements 4 are shaped. Also, the packing elements 4 may be produced from woven material, e.g. from a wire mesh material.
In particular in the case of metal packing elements 4, a piece of channel-shaped section or flat strip can be bent into a ring shape, possibly while simultaneously forming the concavity, and a small gap 10 may be left between the two opposite ends (Fig. 3). The width of this gap should be much smaller than the height H of the packing element 4, so that no other packing element 4 can become wedged or hooked up in this gap when the column 1 is filled.
The ends of a section of profiled strip which has bent into a ring shape may, however, also be joined together by rivetting, soldering, bonding, etc.
Because of the outwardly concave structure of the wall 6, the packing element 4 possesses two circumferential rims 11, one of which may be slightly set back in relation to the other, i.e. the diameter of the two rims 11 may be slightly different, so that the packing element 4 is additionally encouraged to fall into the flat-lying position. The difference in diameter may be so large that the projection of the centre of gravity of the packing element 4 in its substantially vertical position lies on a plane outside its actual base area.
1333~0 In the form depicted, the liquid distributor 5 comprises a feed channel 12 for the liquid phase, which overflows into distribution channels 13. The bottoms of the latter possess a number of outlet conduits 14 with outlet openings 15. The outlet conduits 14 are grouped in such a way that their outlet openings 15 lie in a circle corresponding to one of the packing elements 4 situated beneath them in the uppermost layer 3 of the packing 2. Through this design, the liquid emerging from the outlet openings 15 can be directed onto the packing elements 4 in the uppermost layer 3 and cannot fall free in a random stream through the packing 2. In order to ensure the alignment of the packing elements 4 in the uppermost layer 3 with the groups of outlet conduits 14, whose outlet openings 15 are arranged in a circular pattern, the packing elements 4 in the uppermost layer 3 may be joined by struts 16 or similar, so that the uppermost layer 3 of the packing 2 is placed in the column 1 together with the liquid distributor 5.
Instead of this, the uppermost layer 3 of the packing 2 may also consist of interlinked packing elements 4, and ideally one packing element 4 in the first layer 3 is arranged beneath each outlet opening 15.
The uppermost layer 3, which forms a unit, can at the same time be used as a hold-down for the packing 2 to prevent the latter from lifting up under the action of excess gas pressure.
The liquid distributor 5 by itself or together with the uppermost layer 3 can form the hold-down unit, or both may be a part of the hold-down unit.
In the case of packing elements 4 with a correspondingly small diameter, the outlet openings 15 or the outlet conduits 14 are usually not grouped together, although it is advantageous if at least one outlet opening 15 is assigned to each packing element 4, and this openin~ delivers the liquid phase flowing ~rom it ont~ thi~ packing element 4 in the uppermost layer 3.
g
In mass and heat exchange columns in which a gaseous phase is brought into contact with a liquid phase, a transfer of mass and heat takes place; for example, absorption occurs as a component makes the transition from the gaseous into the liquid phase, or desorption occurs when a component makes the transition in the opposite direction, or rectification occurs when the transition of components takes place in both directions. Since as a rule temperature differences exist, a transfer of heat also simultaneously takes place, and this is why mass exchange columns are always at the same time heat exchange columns as well. As a rule, the gaseous phase is allowed to flow through the column counter-current to the liquid phase; only in rare cases is the co-current flow principle employed (while cross-current flow is considered only for cooling towers in which heat exchange takes place). The columns are provided with filler elements whose task it is to ensure a high exchange performance (efficiency) between the gaseous and the liquid phase, also a high throughput (capacity) for both phases and the lowest possible pressure loss.
Filler elements for mass and heat exchange columns may take the form of unordered as well as ordered packings.
Ordered packings consist preferably of coarsely folded lamellae arranged with their crests crossing at an angle to each other and to the column axis, and also provided with a fine structure in the form of grooves and holes, or similar. It is a relatively complicated matter to manufacture and arrange these packings in the column.
- 13334~l~
Unordered packings consist of individual packing elements which are simply poured into the columns. Compared with ordered packings, it is therefore a much simpler matter to arrange these packings in the column. Such packing elements include the Raschig rings, which have been known for a long time and which possess a ratio of about 1:1 between their diameter and height. A further refinement of these structures are the Pall rings, which possess small tongues extending inwards and leaving corresponding holes in the rings, thereby considerably boosting capacity. Dead zones have been reduced in the Pall rings by reducing the ratio between diameter and height to 3:1, by leaving out a row of tongues.
A similar development has also taken place in the case of roof-shaped, semi-cylindrical, saddle-shaped, or similarly shaped packing elements which are also poured in random manner into the column and which are provided with increasingly complicated surface configurations in the form of holes, ribs, grooves, projections, depressions, tongues, etc.
Due to their structural characteristics, unordered packings exhibit a relatively high pressure loss in the axial direction of the column which impairs the capacity of the packing and the effectiveness of the mass exchange.
This is also true of packings which are manufactured from packing elements of the kind described in DE-A-2 164 144.
These packing elements may be circularly cylindrical in shape, with possi~ly a concave outer surface and with inward-pointing ribs, which may also project axially relative to the cylindrical section. The ribs are intended to prevent the packing elements from becoming wedged inside one another when they are poured into the column, and the drop in pressure which would be caused by this partial alignment of the packing elements is, as a result, reduced. It is a compli~ated matter to provide these ribs, at least in the case of packing elements made of cold-formed metal, and when the packing elements are poured into a column they do not arrange themselves in a well-ordered structure, but instead the packing structure is random and unordered, and it contains not only flat-lying, but also obliquely and vertically oriented 1333k7~
packing elements which still cause a relative high loss of pressure.
It is an object of the invention to provide a packing of the kind mentioned at the beginning, which results in a reduced pressure loss and increased capacity and effectiveness of the mass exchange.
This problem is solved by producing the packing from a large number of layers arranged one on top of the other, each layer containing flat-lying, randomly distributed packing elements each having a free cross sectional opening and with a ratio of external diameter to height of about 6:1 to about 10:1.
The packing elements used consist of a ring, similar to a bicycle wheel rim, with a relatively high ratio of diameter to height, so that in a free fall onto a flat substrate, the packing elements assume a flat-lying position in which they rest on a circumferential edge. The probability that at the end of the fall they will come to rest in a vertical position is extremely slight, because this position is an unstable state of balance which would be eliminated by the slightest vibration, or similar, for example the impact of further falling packing elements. As a result, it is possible, by gradually pouring packing elements into a column and distributing them therein, to build up a packing consisting of successive layers of flat-lying packing elements; such a packing is, so to speak, ordered in the axial direction of the column, while the packing elements in each layer are randomly distributed in an unordered manner and each packing element is practically always offset in relation to the immediately adjacent element above or below. In a packing of this kind, the pressure loss is considerably reduced relative to a completely disordered packing, thus permitting considerable improvements in the capacity and effectiveness of the mass exchange. For the same capacity and effectiveness, the volume and thus the weight of the packing are reduced.
In addition, the packing can be built up from packing elements which are very easy to manufacture and also require relatively little effort to install when the column is being filled.
Further features and advantages of the invention are contained in the following description and in the sub-claims.
The invention is described in more detail below on the basis of the embodiments depicted in the attached Figures.
Fig. 1 shows a section of a packing in a mass and heat exchange column; the rings are shown offset in the plane of the drawing while, for reasons of clarity, rings which have been cut through are not shown.
Fig. 2 shows a top view of a section of the packing seen in Fig. 1.
Fig. 3 shows a possible design of a packing element for the packing in Fig. 1.
In accordance with Fig. 1, a column 1 contains a packing 2 supported on an appropriate base (not shown) and consisting of superimposed layers 3 of packing elements 4. A
liquid distributor 5 is located above the packing 2.
The packing elements 4 have the shape of an annular hollow cylinder, and the wall 6 of the hollow cylinder is of essentially uniform thickness and is provided circumferentially with a concave outer side 7 and a convex inner side 8. In addition, the ratio of the outer diameter D to the height H of the hollow cylinder is so large that when they are poured into a column 1, the packing elements 4 assume a flat-lying position on the floor of the column or on a layer of identical packing elements 4. The ratio of the outer diameter D to the height H of the hollow cylinder is preferably between 6:1 and 10:1.
By carefully filling such packing elements 4 into a column 1, and allowing them to spread out in the column, a packing 2 of superimposed layers 3 of flat-lying packing elements 4 is built up. A packing 2 of this kind exhibits an irregular arrangement of the packing elements 4 in each layer 3, with more or less large spaces being left between the individual packing elements 4, although individual packing elements 4 are also in contact with each other at certain points; however, the packing 2 is ordered in the direction of the column axis.
This means that the aerodynamic resistance is reduced compared with that of a totally unordered packing and thus the 1~3347~
drop in pressure within the column 1 is reduced. Because of the partially ordered packing which can be achieved with the packing elements 4, these packing elements 4 also take up less space for the same specific surface area, i.e. the packing factor is reduced or the capacity of the packing 2 can be substantially increased for the same packing volume.
The concave wall 6 of the packing element 4 provides the latter with sufficient strength and also serves to ensure that a packing element 4 can practically never become jammed obliquely or vertically in a horizontal packing element 4, thus preventing the formation of layers 3 at least in certain sections of the packing; but instead, in such a position the packing element would be in an unstable state of equilibrium and therefore, as further packing elements 4 spread out or fall in the column, it would tip over into the horizontal position because of the unstable state of equilibrium.
Advantageously the wall 6 has a circular, and especially a semi-circular, cross section but partially oval concavities are also, for example, possible.
The concave wall 6 also achieves a corresponding increase in surface area, which reduces the pressure loss and increases the effectiveness and the capacity.
The concave wall 6 also means that the liquid phase flows out without any liquid accumulating, so the dwell time of the liquid phase in the packing 2 is correspondingly short. As a result, polymerizations in substances which tend to polymerize can be avoided in the column 1. In addition, the liquid phase does not hold back any solids held in suspension or entrained in any other way.
In a packing 2 according to Fig. 1, the gaseous phase always flows from top to bottom in the axial direction of the column 1 and thus essentially in the axial direction of the individual packing elements 4, and these create a pressure difference between the area adjacent to the outer side 7 and the area adjacent to the inner side 8, and the static pressure pl at the outer side 7 is greater than the static pressure p2 at the inner side 8 tsimilar to the pressure conditions around the wing 1333~70 of an aircraft). This means that a negative pressure exists inside each individual packing element 4, having internally an open cross section, without any inwards projecting ribs, or similar built-in elements. This gives rise to intense gas turbulences and thus to corresponding cross mixing of the gaseous phase, particularly since each individual packing element 4 is slightly offset relative to the adjacent elements in the layers above and below.
Since the liquid phase runs at least partially along the lower edge of the packing element 4, until it comes into contact with the upper edge of a subjacent packing element 4, this causes a mixing of the downward-flowing liquid phase in the direction transverse to the column axis. In this way, an essentially h~mogeneous composition of the liquid phase over the column cross section is achieved.
The cross mixing of the gaseous and liquid phases means that optimum use can be made of the driving temperature and/or concentration gradient.
Precise horizontal adjustment of the packing 2 or of the packing elements 4 is not necessary; a slight inclination leads to a corresponding outflow of the liquid phase.
The thickness of the wall 6 may, for example, be between about 0.2 and 5.0 mm, while the outer diameters D are usually selected in the range from 10 to 300 mm. The minimum ratio that can be selected between column diameter and packing element diameter, without suffering any loss of effectiveness, is about 4.6:1, compared with a minimum ratio of 8 to 12:1 in the case of customary unordered packings so that, in particular in laboratory equipment, packing elements 4 having relatively large diameters D can be used without any disadvantage.
In the case of packing elements 4 having a smaller diameter D, it is observed that these can sometimes come to rest vertically or at an oblique angle against the walls of the column. This is advantageous in columns 1 having a small column diameter in which normally a large amount of liquid flows down the wall of the column, because the liquid is deflected away from the wall into the interior of the column. For this purpose, it is 133~470 also possible to set up packing elements 4 correspondingly along the wall of the column, as shown in Fig. 1.
The packing elements 4 may be made of a variety of materials, for example metal such as carbon steel, stainless steel, titanium, copper, brass, aluminium, etc., which can ideally be cold formed; or they can be made from thermoplastic material such as polypropylene, polyvinyl chloride, polyethylene or similar; ceramic material, rubber or glass may also be used.
The starting material used in the manufacturing process can be provided before, during or after manufacture with a coarse structure, e.g. by forming gas flow openings 9 (Fig. 3), or similar, over which the liquid phase does not normally flow, or similar, and/or they can be given a fine structure in the form of grooves, elevations, depressions, small holes, or similar. The forming of these structures depends on the way in which the packing elements 4 are shaped. Also, the packing elements 4 may be produced from woven material, e.g. from a wire mesh material.
In particular in the case of metal packing elements 4, a piece of channel-shaped section or flat strip can be bent into a ring shape, possibly while simultaneously forming the concavity, and a small gap 10 may be left between the two opposite ends (Fig. 3). The width of this gap should be much smaller than the height H of the packing element 4, so that no other packing element 4 can become wedged or hooked up in this gap when the column 1 is filled.
The ends of a section of profiled strip which has bent into a ring shape may, however, also be joined together by rivetting, soldering, bonding, etc.
Because of the outwardly concave structure of the wall 6, the packing element 4 possesses two circumferential rims 11, one of which may be slightly set back in relation to the other, i.e. the diameter of the two rims 11 may be slightly different, so that the packing element 4 is additionally encouraged to fall into the flat-lying position. The difference in diameter may be so large that the projection of the centre of gravity of the packing element 4 in its substantially vertical position lies on a plane outside its actual base area.
1333~0 In the form depicted, the liquid distributor 5 comprises a feed channel 12 for the liquid phase, which overflows into distribution channels 13. The bottoms of the latter possess a number of outlet conduits 14 with outlet openings 15. The outlet conduits 14 are grouped in such a way that their outlet openings 15 lie in a circle corresponding to one of the packing elements 4 situated beneath them in the uppermost layer 3 of the packing 2. Through this design, the liquid emerging from the outlet openings 15 can be directed onto the packing elements 4 in the uppermost layer 3 and cannot fall free in a random stream through the packing 2. In order to ensure the alignment of the packing elements 4 in the uppermost layer 3 with the groups of outlet conduits 14, whose outlet openings 15 are arranged in a circular pattern, the packing elements 4 in the uppermost layer 3 may be joined by struts 16 or similar, so that the uppermost layer 3 of the packing 2 is placed in the column 1 together with the liquid distributor 5.
Instead of this, the uppermost layer 3 of the packing 2 may also consist of interlinked packing elements 4, and ideally one packing element 4 in the first layer 3 is arranged beneath each outlet opening 15.
The uppermost layer 3, which forms a unit, can at the same time be used as a hold-down for the packing 2 to prevent the latter from lifting up under the action of excess gas pressure.
The liquid distributor 5 by itself or together with the uppermost layer 3 can form the hold-down unit, or both may be a part of the hold-down unit.
In the case of packing elements 4 with a correspondingly small diameter, the outlet openings 15 or the outlet conduits 14 are usually not grouped together, although it is advantageous if at least one outlet opening 15 is assigned to each packing element 4, and this openin~ delivers the liquid phase flowing ~rom it ont~ thi~ packing element 4 in the uppermost layer 3.
g
Claims (15)
1. A packing for a mass and heat exchange column in which a gaseous and liquid phase are brought into contact with one another, comprising a large number of identical packing elements having essentially the shape of a circular hollow cylinder, whose wall is circumferentially concave to the outside and convex to the inside and forms two external circumferential rims, in which the ratio of outer diameter to height is large, wherein the packing consists of a large number of layers superimposed one on top of the other, and each layer contains a random distribution of packing elements having an internally open cross section, and also having a ratio of outer diameter to height of about 6:1 to about 10:1.
2. A packing according to Claim 1, wherein in the packing elements, the diameter of one circumferential rim is slightly smaller than the diameter of the other circumferential rim.
3. A packing according to Claim 1, wherein packing elements rest vertically or at an angle against the inner wall of the column to deflect any liquid phase flowing down the inner wall of the column into the interior of the column.
4. A packing according to one of the Claims 1, 2 or 3, wherein that the packing elements possess a surface structure to improve the distribution of liquid thereon.
5. A packing according to one of the Claims 1, 2 or 3, wherein the wall of the packing elements is provided with gas flow openings.
6. A packing according to one of the Claims 1, 2 or 3, wherein the packing elements are made from cold formed metal.
7. A packing according to one of the Claims 1, 2 or 3, wherein the packing elements are made from cold formed metal, from a section of flat strip, leaving a narrow gap between the ends of the strip.
8. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor.
9. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the liquid distributor has outlet openings of which at least one in each case is allocated to a packing element in the uppermost layer of the packing.
10. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the liquid distributor has outlet openings of which at least one in each case is allocated to a packing element in the uppermost layer of the packing, the liquid distributor being provided with a large number of outlet openings arranged in circular groups, each of which is positioned above a designated packing element in the uppermost layer in such a way that the liquid emerging from the outlet openings impinges on the packing elements in the uppermost layer.
11. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the packing elements in the uppermost layer are connected to the liquid distributor.
12. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the packing elements in the uppermost layer are connected with each other.
13. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the packing elements in the uppermost layer are connected to the liquid distributor, the liquid distributor and/or the uppermost layer, which forms a unit, constituting or forming a part of a hold-down device.
14. A liquid distributor for a packing according to one of the Claims 1, 2 or 3, having a supply channel, from which branch off distribution channels and from these distribution channels branch off outlet conduits provided with outlet openings, wherein the outlet openings in the outlet conduits are grouped in circular patterns, each group corresponding to one of the underlying circular packing elements in the uppermost layer of packing elements in the packing.
15. A packing according to one of the Claims 1, 2 or 3, wherein the uppermost layer of the packing is arranged in a predetermined manner relative to an overlying liquid distributor, such that the packing elements in the uppermost layer are connected to the liquid distributor wherein a layer of flat-lying, adjacent packing elements is connected with the liquid distributor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BRPI8804209 | 1988-08-11 | ||
| BR8804209A BR8804209A (en) | 1988-08-11 | 1988-08-11 | DISORDERED FILLING |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1333470C true CA1333470C (en) | 1994-12-13 |
Family
ID=4045403
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000607954A Expired - Fee Related CA1333470C (en) | 1988-08-11 | 1989-08-10 | Packing for a mass and heat exchange column |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0396647B1 (en) |
| JP (1) | JPH03500384A (en) |
| AU (1) | AU617516B2 (en) |
| BR (1) | BR8804209A (en) |
| CA (1) | CA1333470C (en) |
| DE (1) | DE58909845D1 (en) |
| MX (1) | MX172894B (en) |
| WO (1) | WO1990001368A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004027996A1 (en) * | 2004-06-09 | 2005-12-29 | Julius Montz Gmbh | Packings and packing for heat and mass transfer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1427712A (en) * | 1972-02-28 | 1976-03-10 | Mass Transfer Ltd | Fluid-fluid contact apparatus |
| GB1385672A (en) * | 1970-12-18 | 1975-02-26 | Mass Transfer Ltd | Fluid-fluid contact apparatus |
| DE2310434C2 (en) * | 1970-12-18 | 1985-02-28 | Mass Transfer Ltd., Kendal, Westmorland | Packing for exchange and contact columns |
| GB8412927D0 (en) * | 1984-05-21 | 1984-06-27 | Mass Transfer Ltd | Packing elements |
-
1988
- 1988-08-11 BR BR8804209A patent/BR8804209A/en not_active Application Discontinuation
-
1989
- 1989-08-05 JP JP50828489A patent/JPH03500384A/en active Pending
- 1989-08-05 DE DE58909845T patent/DE58909845D1/en not_active Expired - Fee Related
- 1989-08-05 AU AU40418/89A patent/AU617516B2/en not_active Ceased
- 1989-08-05 WO PCT/EP1989/000928 patent/WO1990001368A1/en active IP Right Grant
- 1989-08-05 EP EP89908971A patent/EP0396647B1/en not_active Expired - Lifetime
- 1989-08-10 CA CA000607954A patent/CA1333470C/en not_active Expired - Fee Related
-
1994
- 1994-01-19 MX MX9417158A patent/MX172894B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR8804209A (en) | 1988-11-29 |
| AU617516B2 (en) | 1991-11-28 |
| MX172894B (en) | 1994-01-19 |
| EP0396647A1 (en) | 1990-11-14 |
| WO1990001368A1 (en) | 1990-02-22 |
| JPH03500384A (en) | 1991-01-31 |
| AU4041889A (en) | 1990-03-05 |
| DE58909845D1 (en) | 1998-11-26 |
| EP0396647B1 (en) | 1998-10-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |