MXPA00004717A - Liquid dispenser for distilling column, and corresponding distilling column - Google Patents

Abstract

The invention concerns a dispenser (1) comprising:a primary dispenser (3) defining a closed volume provided with openings (8) for pre-dispensing liquid emerging in the column;means for supplying the primary dispenser (3) with liquid under pressure very much higher than the pressure inside the column;and a secondary dispenser (4) taking up substantially the whole section of the column, which comprises a gaseous roof communicating with the column internal space and which is subdivided by internal partitions (13, 17) into a plurality of compartments (16) each of which receives the liquid coming from at least one of the primary dispenser (3) said orifices (8), said secondary dispenser (4) comprising a base (9) provided with orifices (12) dispensing fine liquid over almost the whole section of the column, said orifices being much more numerous than the primary dispenser openings (8). The invention is applicable to air distilling on offshore floating terminals or on drilling platforms.

Description

LIQUID DISTRIBUTOR FOR DISTILLATION COLUMN, AND THEIR CORRESPONDING DISTILLATION COLUMNS Field of the Invention The present invention relates to a liquid distributor for distillation column. It applies in particular to air distillation columns shipped on floating structures such as floating oil platforms or vessels.

A -beceden-tes of the Invention.

The pressures that will be addressed below are absolute pressures.

Floating oil platforms produce waste gases. For economic and environmental reasons, it is increasingly necessary to recover these gases. One method is to convert them into heavier hydrocarbons, in liquid form and therefore more easily transportable, through the process Ref: 120046 Fischer-Tropsch, which consumes large amounts of oxygen.

It would therefore be interesting to be able to ship an air distillation column on a floating platform or a boat, but the proper functioning of such equipment faces serious difficulties. For example, a first imperative is that the liquid is evenly distributed in the upper part of the column over the entire section of the column despite the oscillations of its axis caused by the wave.

Description of the invention The object of the invention is to provide a liquid distributor whose operation is very insensitive to such oscillations.

For this purpose, the object of the invention is a liquid distributor for distillation columns, characterized in that it comprises: a primary distributor delimiting a closed volume provided with liquid predistribution openings that open into the column; - means for feeding the primary distributor in liquid under a pressure clearly higher than the internal pressure of the column; and a secondary distributor that occupies the entire section of the column, which contains a gaseous sky in communication with the interior space of the column and which is subdivided by partitions into a multiplicity of compartments, each of which receives liquid originating from less one of said openings of the primary distributor, said secondary distributor comprising a bottom of holes for fine distribution of the liquid over substantially the entire section of the column, the number of such openings being much greater than that of the openings of the primary distributor.

The dispenser according to the invention may comprise one or more of the following characteristics: each compartment receives liquid from a single opening of the primary distributor; all compartments have almost the same area and the same drilling rate; the primary distributor comprises a network of perforated pipes; the network of perforated tubes comprises a series of parallel perforated tubes, each of which is plumbed from a rectilinear gutter of the secondary distributor; said feeding means comprise a phase separator and a compression and feeding conduit connected upwardly of the lower part of this separator; the feeding means pass through a subcooler.

The invention also relates to a distillation column comprising a distributor as defined above.

In one embodiment of such distillation column, said liquid distributor is disposed at a first level of the column, in particular at the top of the column, and this comprises, at least at a second level, collection means of the liquid that crowns a second liquid distributor as defined above and whose primary distributor is connected to second means of understanding the liquid collected.

Next, an embodiment of the invention will be described with reference to the appended drawing, in which: - Figure 1 represents schematically, in vertical section according to line I-I of Figure 2, a liquid distributor according to the invention; - Figure 2 is a schematic plan view of this distributor; - Figure 3 is a partial view analogous to Figure 1, on a larger scale; Y Figure 4 schematically illustrates an air distillation column according to the invention, boarded on a floating structure.

The distributor 1 shown in Figures 1 and 2 is intended to be mounted on top of an air distillation column 2, schematized in Figure 4 as a low pressure column of a double air distillation column.

The distributor 1 is constituted by two parts, namely a primary distributor 3 and a secondary distributor 4 arranged below.

The primary distributor 3 is constituted by a tube 5 which forms a supply manifold, sealed at one end 6, from which several perforated horizontal tubes 7, parallel to each other, are sealed perpendicularly, sealed at their opposite end to the collector. Each tube 7 comprises in its lower generatrix several calibrated holes 8 all identical and whose diameter is between 2 and 5 mm.

In the example shown, seven tubes 7 are provided, and the number of holes 8 is four for both end tubes, twelve for the central tube and ten for the other four tubes. In any case, the total number n of holes of the tubes 7 is much lower than the number N of liquid distribution holes necessary to ensure a fairly uniform distribution of the liquid over the section of the column 2, this number N being typically of the order from 1000 to 3000 for a column of 4 m in diameter. In addition, the diameter of the holes 8 is sufficient to avoid any risk of plugging by impurities contained in the liquid to be distributed.

The secondary distributor 4 comprises a bucket open upwards, with a horizontal bottom 9 and a peripheral cylindrical wall 10 which rises on this bottom. The base 9 comprises six lights 11 of elongated shape according to the direction parallel to the tubes 7, which leave free on the one hand a peripheral annular crown and on the other hand, five bands parallel to said direction. This crown and these bands are perforated by N holes 12 previously mentioned, which have, like the holes 8, a sufficient diameter to avoid any risk of clogging.

Each light 11 is entirely bordered by an ascending vertical wall 13, which delimits with the peripheral wall 10 five rectilinear gutters 14 to lead of the mentioned bands, and a peripheral annular gutter 15 communicating with all the gutters 14.

In addition, the gutters 14 and 15 are all subdivided into compartments 16 by a set of vertical walls 17 extending between the walls 13 and between these and the peripheral wall 10.

The compartments 16 all have the same area and the same perforation rate and each one is below an orifice 8 and only one.

The column 2 is fixed to a floating structure S, schematized in figure 4, just like the medium pressure column of the double distillation column (not shown). In figure 4 only the elements useful for the understanding of the present invention are represented, but the double column comprises all the elements conventional in the art.

More particularly, the column 2 is subdivided into an upper section of distillation 18 and a lower section of distillation 19, both constituted by corrugated-crimp coatings. As it is well known, such a coating comprises a superposition of stretches or packs 20 of corrugated-corrugated coating, each with the shape of a cylindrical disc that occupies the entire section of the column.

Each pack 20 is constituted by a stack of corrugated strips 21 with oblique waves 22. Each band comprises a vertical general plane, all the bands have the same height and the waves are alternately inclined in each direction from one band to the next. In this way, the waves of the adjacent bands touch on a large number of intersection points. further, the packs 20 are angularly offset 90 ° from one pack to the other with respect to the general axis of the column. Above the upper section 18, the column contains a distributor as described above, which is a distributor of the upper part 1A of the column. Below section 18, the column contains a device 23 for collecting the liquid from this distillation section. Below this device 23 and above the distillation section 19, a second distributor is arranged as defined above, which constitutes an intermediate distributor IB.

In service, the "lean liquid" (almost pure nitrogen extracted at the top of the medium pressure column) coming through a supply conduit 24, is compressed at a pressure of the order of 3 bars by a pump 25, then of which is introduced into the feed manifold 5A of the distributor 1. This liquid is released at a pressure of the order of 1.2 bar through the holes 8, falling into the respective compartments 16. From there, it falls through the set of the holes 12 on the upper pack 20 of the distillation section 18.

The liquid coming from this section 18, enriched in oxygen, is collected by the device 23, _sale of the column by a conduit 26 and is sent to a phase separator 27. The liquid collected in the latter is mixed with "rich liquid" of equal composition (air enriched in oxygen, collected in the bucket of the medium pressure column) from the medium pressure column through a conduit 28. Then this liquid is compressed at the mentioned pressure of the order of 3 bars by a pump 29, and inserted into the feed manifold 5B of the distributor IB. From there, it is released and distributed in two stages as before, to supply the reflux of the lower distillation section 19.

By the way, the liquid that descends in column 2 is in relation of matter and heat exchange with the gaseous oxygen obtained by heating of liquid oxygen, collected in the tank of column 2, by nitrogen gas from the top of the medium pressure column. This gas is progressively enriched in nitrogen when ascending to column 2.

The gaseous circulations have not been represented in figure 4 for clarity. However, it is understood that the ascending gas passes through the distributors 1A and IB without difficulty through their lights 11. Likewise, the collector device 23 contains steps that allow this free ascending passage. In fact, it is constituted by a series of rectilinear gutters 30, each of which comprises a lateral wall obliquely upwards at 31 to cover the interval separating it from the gutter next to it, leaving a passage 32 for the gas free.

When structure 18 is at sea, the axis of column 2 oscillates around its normally vertical position. The terms "horizontal" and "vertical" used previously to describe the distributor 1, should be understood for this median position of the column, but, when it is inclined, the tube layer 7, the bottom 9 and the walls 10, 13 and 17 are tilted at the same angle, as represented by figures 1 and 3.

Thanks to the preesurization of the liquid in the primary distributor 3, everything happens as if the holes 8 were crowned by a liquid height of the order of 20 m, if of course the corresponding height space. Accordingly, the height variations between the most extreme holes 8 have a very little influence on the flow rates produced by these orifices.

Furthermore, in each compartment 16, the small distance separating the holes 12 (Figure 3) results in the height of liquid crowning them varying little from one hole to the other. It is also observed that at all times, the strongly-fed orifices 12A are next to the holes 12B poorly fed from an adjacent compartment, so that both flow rates are easily compensated in the same region of the upper pack 20 of the distillation section. immediately underlying.

In total, a distribution of the liquid with satisfactory uniformity is obtained throughout the section of the column even in the case of a relatively strong inclination of the column.

To avoid flash phenomena (vapor formation) when the liquid is released in the holes 8, it is convenient to subcool the compressed liquid, by any appropriate means, in particular by heat exchange with a cooler fluid, available in the installation of distillation. This fluid can be impure nitrogen from the top of the column and / or liquid nitrogen under a pressure lower than that of the liquid in question.

In addition, the compression of the liquid to be distributed can be obtained, with or without pump, depending on the case, using a hydrostatic head. The liquid is then traced back to a phase separator at an appropriate level. For this purpose, an entrained gas can be used under a sufficiently high pressure and / or with a thermosiphon effect by partial evaporation of the liquid in a heat exchanger.

As can be understood, the invention also applies to the distribution of reflux liquid in a fixed column but whose axis is not perfectly vertical.

The application WO-A-90/10 497 discloses, inter alia, a coating analogous to the aforementioned wavy-cross coatings, but perforated differently. The term "corrugated-crimp coating" used herein also comprises such a coating, as well as any analogous coating.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

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

Claims (10)

Claims

1. A liquid distributor for distillation column, characterized in that it comprises: - a primary distributor delimiting a closed volume provided with liquid predistribution openings that open into the column; means for feeding the primary distributor in liquid under a pressure clearly higher than the internal pressure of the column; and a secondary distributor that occupies almost the entire section of the column, which contains a gaseous sky in communication with the interior space of the column and which is subdivided by partitions into a multiplicity of compartments, each of which receives liquid from at least one of the openings of the primary distributor, the secondary distributor comprising a bottom provided with holes for fine distribution of the liquid over practically the entire section of the column, the number of such holes being much greater than that of the openings of the primary distributor .

2. The dispenser according to claim 1, characterized in that each compartment receives liquid from a single opening of the primary distributor.

3. The dispenser according to claim 1 or 2, characterized in that all the compartments have almost the same area and the same perforation rate.

4. The dispenser according to any of claims 1 to 3, characterized in that the primary distributor comprises a network of perforated tubes.

5. The dispenser according to claim 4, characterized in that the network of perforated tubes comprises a series of parallel perforated tubes, each of which is plumbed from a rectilinear gutter of the secondary distributor.

6. The dispenser according to any of claims 1 to 5, characterized in that the feeding means comprise a phase separator and a compression and supply conduit connected upwards in the lower part of this separator.

7. The dispenser according to any of claims 1 to 6, characterized in that the feeding means passes through a subcooler.

8. A distillation column, characterized in that it comprises a liquid distributor according to any of claims 1 to 7.

9. The distillation column according to claim 7, characterized in that the liquid distributor is disposed at a first level of the column, specifically at the top thereof, and because the column comprises, at least at a second level, means of collecting the liquid ascending to a second liquid distributor according to any of claims 1 to 7 and whose primary distributor is connected to second means of understanding the liquid collected.

10. The distillation column according to claim 8 or 9, characterized in that it is shipped on a floating structure such as a floating oil platform or a vessel. Summary of the Invention A dispenser comprising - a primary distributor (3) delimiting a closed volume provided with liquid pre-distribution openings (8) opening "on the column; - means for feeding the primary distributor (3) in liquid under a pressure clearly greater than the internal pressure of the column, and a secondary distributor (4) that occupies almost the entire section of the column, which contains a gaseous sky in communication with the interior space of the column and which is subdivided by partitions (13, 17) into a multiplicity of compartments (16), each of which receives liquid from at least one of said openings (8) of the primary distributor (3), the secondary distributor (4) comprising a bottom (9) provided with holes (12) of fine distribution of the liquid over practically the entire section of the column, the number of such holes being much greater than that of the openings (8) of the primary distributor.The invention is applicable to the distillation of air on floating oil platforms or vessels.