Distributor tray for gas/liquid exchange column with liquid deflector

Abstract

The present invention relates to a distributor tray (2) for a column intended for heat and/or material exchange between a gas and a liquid. The tray comprises gas passage means (4), liquid passage means (6) and distribution means (5) for distributing the liquid with a preferred orientation. The invention also relates to a heat and/or material exchange column, and to the use of the column.

Claims

1. A column intended for heat and/or material exchange between a gas and a liquid, comprising: a structured packing comprising a plurality of plates; and at least one distributor tray comprising: a tray provided over a section of the column; at least one casing provided on the tray, each casing having a gas passage configured to allow the gas to pass through the tray; at least one chimney provided on the tray, each chimney having a liquid passage, separated from the gas passage of the at least one casing, configured to allow the liquid to pass from above the tray, through the tray to an underside of the tray; and at least one deflector projecting beyond a lower part of the tray configured to distribute the liquid coming from the at least one chimney with a preferred orientation, the at least one deflector comprising a pipe fastened to the at least one chimney and having a longitudinal axis arranged parallel to the tray and extending in a longitudinal direction substantially perpendicular to a principal direction, in a transverse horizontal plane, of the plates of an upper layer of the structured packing, the pipe having a plurality of orifices provided through the pipe arranged along the longitudinal axis of the pipe, and a dispersion plate arranged in the pipe and located below the at least one chimney for dispersing a jet coming from the at least one chimney towards the plurality of orifices.

2. A column as claimed in claim 1, wherein said at least one deflector is fastened to said at least one chimney by screwing, welding, gluing or insertion in said at least one chimney.

3. A column as claimed in claim 1, wherein the at least one deflector is configured to distribute the liquid in form of at least one jet.

4. A column as claimed in claim 1, wherein a plurality of chimneys is provided and each deflector is shared by several chimneys.

5. A column as claimed in claim 1, wherein said plurality of orifices is located in an upper part of said pipe, said at least one deflector being provided with a further deflector for sending the liquid at an outlet of said plurality of orifices downwards.

6. Use of a column as claimed in claim 1 for a gas treatment, CO.sub.2 capture, distillation or air conversion method.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other features and advantages of the method according to the invention will be clear from reading the description hereafter of embodiments given by way of non limitative example, with reference to the accompanying figures wherein:

(2) FIG. 1, already described, illustrates the particular case of a gas treatment or CO.sub.2 capture column top equipped with a distributor tray,

(3) FIG. 2, already described, illustrates a distributor tray according to the prior art,

(4) FIG. 3 illustrates an example of a structured packing,

(5) FIG. 4 illustrates an example of a distributor tray according to the invention,

(6) FIG. 5 illustrates a chimney of a distributor tray according to the invention,

(7) FIG. 6 diagrammatically illustrates the liquid distribution means of a distributor tray according to the invention,

(8) FIG. 7 illustrates a first embodiment of the liquid distribution means according to the invention,

(9) FIG. 8 illustrates a second embodiment of the liquid distribution means according to the invention,

(10) FIG. 9 illustrates a third embodiment of the liquid distribution means according to the invention,

(11) FIG. 10 illustrates a fourth embodiment of the liquid distribution means according to the invention,

(12) FIG. 11 illustrates a fifth embodiment of the liquid distribution means according to the invention,

(13) FIGS. 12a and 12b illustrate a sixth embodiment of the liquid distribution means according to the invention.

DETAILED DESCRIPTION

(14) The invention relates to a distributor tray for a column intended for heat and/or material exchange between a gas and a liquid, conventionally comprising at least one means allowing passage of the gas through the tray, such as a casing, at least one chimney for passage of the liquid through the tray and at least liquid distribution means. The distributor tray allows to form a liquid guard level on the upper surface thereof. The casings and the chimneys project beyond the upper part of the tray (oriented towards the top of the column), whereas the liquid distribution means project beyond the lower part of the tray (oriented towards the bottom of the column). According to the invention, the liquid distribution means distribute the liquid coming from the chimneys below the tray with a preferred orientation. The preferred orientation is determined depending on the application of the tray (distillation, gas treatment, etc.) and/or the type and the orientation of the contactor (structured packing for example) used in the column. The distributor tray according to the invention is suited for counter-current flows in the heat and/or material exchange column, the gas flowing upward through the casings and the liquid flowing downward through the chimneys and the distribution means. However, it is also suited for co-current flows.

(15) FIG. 4 illustrates a distributor tray according to an embodiment of the invention. For this embodiment example, distributor tray (2) is equipped with casings (4) allowing passage of the gas through the tray, chimneys (6) allowing passage of the liquid through tray (2) and liquid distribution means (5). Liquid distribution means (5) are connected to chimneys (6) and they are all oriented in the same direction so as to distribute the liquid in a preferred direction. The liquid is distributed through orifices provided on the liquid chimneys towards liquid distribution means (5), also referred to as deflectors. According to the embodiment illustrated by way of example, there is a liquid distribution means (5) for each chimney (6).

(16) The casing intended for passage of the gas allows, for a column operating in counter-current mode, passage of the gas from the underside to the top side of the tray. Advantageously, the gas passage casing has a substantially parallelepipedic shape, so as to provide a wide opening for passage of the gas and to limit pressure drops. Furthermore, when the distributor tray comprises several casings for passage of the gas, they can be arranged parallel to one another. The gas passage casings are preferably covered with a cap (also referred to as bevel) for preventing the liquid from flowing into the casings.

(17) The liquid passage means allow passage of the liquid from the top to the underside of the tray. According to the invention, the means allowing passage of the liquid through the tray consist of a set of chimneys. These chimneys, of substantially tubular shape, are arranged between the casings allowing passage of the gas. The number of chimneys is advantageously larger than the number of gas passage casings. The pitch of the chimneys for passage of the liquid can be triangular or square.

(18) FIG. 5 is an example of a chimney (6) that can be used for the distributor tray according to the invention. Height H of chimney (6) is lower than the height of the gas passage casings (for example, a chimney (6) can be 600 mm high and a casing can be 700 mm high). In order to prevent liquid from flowing into the gas passage casings when the liquid guard height is great, the chimney has an opening (10). This opening also allows the pressure to be balanced within the chimney. Furthermore, chimney (6) has a cap (or bevel) for preventing liquid from flowing directly into chimney (6). Chimney (6) comprises at least one and preferably, as shown, two radial orifices (9) for inflow of the liquid into the chimney, the liquid being conveyed by gravity beneath the tray. Preferably, when chimney (6) comprises at least two radial orifices (9), they are located at different heights: h.sub.R1 and h.sub.R2. Thus, when the liquid flow rate is low, the liquid guard height on the tray (height of liquid in relation to the tray level) is low, only the first radial orifice allows liquid to flow through the tray. When the liquid flow rate is higher, the liquid guard height increases, and the first and second radial orifices allow the liquid to flow through the tray. Due to this characteristic, the distributor tray is suited to various flow rates, it is therefore flexible. The chimney can also comprise several orifice levels (more than 2).

(19) The liquid distribution means allow to distribute the liquid contained in the chimneys onto a contactor, notably a packing (FIG. 1). Packing (3) can be a structured packing as shown in FIG. 3. In this figure and in the next figures, the packing is diagrammatically shown in a non limitative way. A structured packing is generally made up of a set of plates so oriented as to promote exchanges between the liquid and the gas. An example of a structured packing is notably described in patent FR-2,913,353 (US-2010/0,213,625). According to the example illustrated in FIG. 3, the structured packing consists of at least two structured packing sections (T1 and T2). Conventionally, sections (T1 and T2) arranged one above the other are oriented perpendicular to one another. In order to increase the exploited surface area of upper section (T1), the liquid distribution is oriented by the liquid distribution means. The liquid distribution means can therefore be arranged substantially perpendicular to the direction, in a transverse plane, of the plates of upper section (T1) of the structured packing. Indeed, the plates that make up the structured packing comprise, in the transverse plane, a principal direction and the liquid distribution means (5) are orthogonal to this direction. Thus, all the packing plates of the first section are also exploited.

(20) According to one embodiment of the invention, the distribution means have the shape of a cylindrical pipe equipped with means of connection to at least one chimney. Alternatively, the pipe can occur in other shapes, for example prismatic, parallelepipedic, etc. The pipe can be substantially parallel to the tray. The pipe can be equipped with liquid passage means, notably in form of orifices or tubes, preferably bevelled, the liquid passage means allowing distribution with the preferred orientation of the liquid from the pipe to the packing. Advantageously, the liquid passage means distribute the liquid in form of a liquid jet without forming droplets. The pipe is fastened to at least one chimney by the connecting means, notably by screwing, welding, gluing or insertion in the chimney. Connection of the pipe can notably be achieved by means of an internal or external thread.

(21) FIG. 6 illustrates an example of a distributor tray (2) arranged above a structured packing (3). In FIG. 6, the means allowing passage of the gas through tray (2) are not shown. According to the embodiment illustrated, chimneys (6) allowing passage of the liquid project on both sides of tray (2). Cylindrical pipes (5) are fastened onto the projection of chimneys (6) on the lower side of tray (2). Cylindrical pipes (5) are parallel to tray (2) and perpendicular to the orientation of structured packing (3), i.e. to the direction of the plates of the upper layer of said structured packing (3) in the transverse plane. The plates that make up the structured packing comprise, in the transverse plane, a principal direction, pipes (5) being orthogonal to this direction. The cylindrical pipes comprise several liquid passage means forming liquid jets on structured packing (3). Liquid jets (L) are represented in black in FIG. 6. Thus, the liquid is more homogeneously distributed over the packing with a preferred orientation and in form of a jet, which promotes material and/or heat exchanges between the gas and the liquid at the packing.

(22) FIGS. 7 to 12 show different embodiments of the distribution means in form of a cylindrical pipe. For these figures, identical elements have the same reference signs. For the description of these figures, only the changes brought to the distribution means of FIG. 6 are described.

(23) FIG. 7 shows a first embodiment of the distribution means according to the invention. According to this embodiment, the lower part of distribution pipe (5) comprises several orifices (7) sufficiently small to maintain a water guard level and thus to evenly distribute the liquid stream. Orifices (7) can be aligned in the axial direction of cylindrical pipe (5). Advantageously, orifices (7) are substantially circular. Pipe (5) is fastened by connecting means to the outer face of the lower projection of chimney (6).

(24) FIG. 8 shows a second embodiment of the liquid distribution means. According to this embodiment where liquid passage means (7) are identical to those of FIG. 7, pipe (5) furthermore comprises a plate or a deflector (8) arranged in cylindrical pipe (5) and located below liquid chimney (6) so as to disperse the descending liquid flow inertia and to prevent supply heterogeneity. As illustrated in this figure, the lower projection of chimney (6) is bevelled. The shape of the chimney projection is not limitative and it can be combined with all the embodiments described.

(25) FIG. 9 shows a third embodiment of the liquid distribution means. According to this embodiment, the liquid passage means are provided in the lower part of cylindrical pipe (5) by means of a slot (11). Slot (11) can have a rectangular, oblong or similar shape. In this figure, a deflector (8) is shown, but it is optional.

(26) FIG. 10 shows a fourth embodiment of the liquid distribution means. According to this embodiment, chimney (6) comprises no lower projection on the lower side of tray (2) and the primary liquid outlet is provided by an orifice flush with lower plate (2) of the distributor, the tube of cylindrical pipe (5) being inserted in this orifice, by screwing for example. As illustrated here, cylindrical pipe (5) comprises several orifices (7) such as described in reference to the first embodiment. This embodiment can be combined with the third embodiment, orifices (7) can be replaced by a slot (11). Moreover, in this figure, a deflector (8) is shown, but it is optional.

(27) FIG. 11 shows a fifth embodiment of the liquid distribution means. According to this embodiment, cylindrical pipe (5) is simultaneously fastened to several chimneys (6) projecting beneath tray (2), notably so as to run right through the column from one end to the other. This embodiment is illustrated with a series of orifices (7) and a series of deflectors (8). However, the series of orifices (7) can be replaced by one or more slots (11). Furthermore, deflectors (8) are optional.

(28) FIGS. 12a (front view) and 12b (profile view) show a sixth embodiment of the liquid distribution means. According to this embodiment, cylindrical pipe (5) is equipped with an opening in the upper part thereof in form of a slot and with a deflector (12) for driving the liquid downwards while preventing the formation of fine droplets. The arrows in FIG. 12b illustrate the flow of the liquid in cylindrical pipe (5).

(29) Alternatively, according to variant embodiments that are not shown, orifices (7) of the first, second and fourth embodiments can be replaced by vertical tubes. In order to optimize the orientation of the liquid jet on the packing, the tubes can be bevelled.

(30) The liquid distribution means (deflector) can be made for new distributor trays or they can also be installed in existing distributors in case of modification of an existing tray.

(31) The invention thus allows to improve the distribution at least over a first structured packing section through oriented distribution means. The invention also allows to increase the number of injection points with small space requirements. Thus, the invention allows a 3% to 5% potential gain in total exploited surface area over a packing height between two distributors. The gain can even be higher because the distribution on the second packing section is also improved.

(32) The invention also relates to a column (1) for material and/or heat exchange between two fluids, wherein two fluids are contacted by means of at least one gas/liquid contactor (3), column (1) comprising at least a first inlet for a liquid fluid, at least a second inlet for a gaseous fluid, at least a first outlet for a gaseous fluid and at least a second outlet for a liquid fluid. Column (1) also comprises a distributor tray (2) as described above, allowing distribution of the fluids onto contactor (3).

(33) In the particular case where the distributor is positioned at the column top, said distributor can be equipped with a divider arranged above the distributor so as to break the liquid jet coming from the main delivery line of the column. The divider also provides good distribution of the liquid onto the distributor.

(34) Advantageously, gas/liquid contactor (3) is a structured packing bed. In this case, the distribution means are oriented perpendicular to the orientation of the upper layer of the structured packing so as to distribute the liquid in a preferred direction promoting material and/or heat exchanges in the packing.

(35) Preferably, the gas and the liquid flow through column (1) under counter-current conditions.

(36) The column according to the invention can be used in gas treatment, CO.sub.2 capture (amine wash for example), distillation or air conversion methods. Furthermore, the invention can be used with any solvent type.