This invention relates to a catalytic chemical reactor comprising a liquid distribution tray device that improves liquid distribution over the cross-sectional area of a vessel following the tray. The catalytic reactors liquid distribution tray also intimately contacts the fluid phases to achieve thermal and compositional equilibrium. The reactor can be a down-flow catalytic reactor which includes vertically superimposed packed beds of particulate catalytic material. This type of reactor is used in the petroleum and chemical processing industries for carrying out various catalytic reactions, such as sulphur and nitrogen conversion (HDS/HDN); hydrogenation of: olefins (HYD) and aromatics

(hydrodearomatisation - HDA), metals removal (hydrodemetallisation - HDM), oxygen conversion (hydrodeoxygenation - HDO) and hydrocracking (HC). BACKGROUND OF THE INVENTION

In catalytic chemical reactors it may be necessary to evenly distribute a liquid phase of the process fluid over the cross-sectional area of a catalytic bed. Therefore, it is known to install a plate section, a liquid distribution tray, with evenly distributed apertures across its area above and process fluid upstream the catalytic bed. The tray then collects liquid which drips/flows through the apertures to the catalytic bed below. A problem may arise is the tray is not perfectly horizontal arranged, the liquid flow through the apertures then becomes uneven across the area of the tray. This has an impact on the chemical reactions and performance of the catalytic bed below, which is then also uneven and not optimal. The performance of a liquid distribution trays are rated based on the homogeneousness of liquid dispersion over the catalyst, whereas correctly performing trays disperse the liquid in a fully homogeneous fashion throughout the whole cycle length.

A distribution tray typically comprises a plurality of downcomers transferring the process gas and liquid downstream. Various technologies are applied to ensure that the amount of liquid entering each downcomer is more or less constant: the most common are bubble cap and vapour-lift transfer tubes, chimney and Venturi-enhanced chimney.

The dispersion of the liquid downstream is typically achieved either by arranging the downcomers in a tight pitch configuration or by a dispersion technology, the most common of which is a splash platelet.

A configuration with a tight pitch is a rugged technology choice. However, as the high pitch is achieved through a large number of downcomers, this technology is associated with a large amount of steel, which increases production price and the environmental footprint of manufacturing of a distribution tray.

Splash platelets are effective in spraying the liquid over a significantly larger area than the cross section of the downcomer exit. However, they protrude below the distribution tray, thereby imposing restriction to the minimum distance between the tray and the top of the catalyst bed. Furthermore, they are shown to plug in presence of dirty feed thereby reducing the effectiveness of dispersion over the cycle and requiring maintenance of the platelets from below the tray. Dispersion by means of a swirling flow are also known from the art. There are several means to achieve swirling flows. Technology for the generation of a swirling flow in a vapour and liquid transfer pipe known in the art require complex mechanical constructions involving additional parts, additional welding and / or cast moulded structures. All of the above is associated to high manufacturing costs.

Thus, a technology for producing a swirling flow by means of simple material readily available in a mechanical workshop, with limited number of parts and limited part of handling is wanted. Distribution by means of a very large number of transfer tubes (or dripping points) is effective in evenly distribute across the surface of a catalyst regardless of the distance of the catalyst bed. On the contrary, expanding flows, as those created by splash platelets and the swirling flows technologies disclosed in the art, require a certain empty space from the bottom of the tray to the top of the catalyst (or grading, or hold down material) to develop. In the absence of an empty space to develop the expansion, catalyst coverage is not even.

In order to maximize the use of reactor space to the benefit of the reaction, the catalyst (or grading, etc.) must be loaded as close as possible to the bottom of the distribution tray. Particularly for small reactors, loading distances of 100 mm or less are not uncommon. Distribution trays comprising a dispersion technology as known in the art have limitation with regards to the balance between the maximum allowable pitch and the minimum allowable distance from the catalyst surface if the even wetting of the catalyst must be obtained. There us therefore the need of a dispersion technology securing even wetting, while the maximum allowable pitch is independent of the minimum allowable distance from the catalyst surface.

SUMMARY OF THE INVENTION

These problems are solved by the present invention, catalytic chemical reactor with a fluid distribution tray comprising swirl distribution units, a distribution technology comprising dispersion by means of a swirling flow. The swirling flow can be achieved by combining two open chambers one inside the other. The internal chamber has a round cross section. The external chamber is closed at the top. Many different geometrical shape forming the cross section of the external chamber may serve the purpose. The two chambers are not necessarily coaxial and the distance between the walls of the two open chambers is not constant. Both chambers have each at least one carved out section creating an opening (by itself or by cooperation of other walls of the structure): for the external chamber the opening serves for the collection of the multiphase fluid from the tray upper environment. In the internals chamber the opening causes the transfer of the multiphase fluid downstream. An embodiment of the invention is shown in the attached file. In the embodiment, the round pipe enveloping the internal chamber, has four carved-out sections at the top. The upper part of the round pipe, is in contact with the ceiling of the external chamber. In this embodiment, the external chamber is enveloped by a portion of a cube - the cube is closed at the top and have for slots that serve as openings. In this embodiment, the internals side of the lateral walls of the cube are in close contact with the external walls of the round tube. During operation, the vapour and the vapour-lifted liquid enter the slots of the cube and move upwards towards the carved-out section of the tube. Due to the close contact between the lateral walls of the cube and the walls of the round pipe, the multiphase fluid has also a tangential component of the velocity. The flow keeps the tangential component entering the round pipe, thereby creating the swirl.

It is obvious that this is only one embodiment as the invention may be realised by plenty of shape combinations. The evenness of spraying can be achieved by designing a nozzle ring at the tip of the tube enveloping the round tube.

The technology may be used with Vapour-Lift transfer tubes (bubble caps, VLTs), with chimney transfer tubes (the opening of the external chamber are not immersed in the liquid, the internal chamber has openings to permit the flowing of the liquid only) and with Venturi-assisted transfer tray.

The swirl distribution units of the invention may be installed on top of a corrugated tray. The angle of the corrugated tray can be modified to envelop the angle of expansion of the jet. The corrugated tray is calibrated such that “all” of the expansion is obtained already at the bottom of the tray. The corrugated structures offer the additional advantage to stiffen the whole tray. Thus, by designing the corrugation in suitable directions, a tray can be built that minimized deflections for the same amount of structural steel.

A further addition to the corrugated tray is that baskets with same shape of the depressions of the corrugated tray may be positioned in the depressions. The baskets are removable, and they have the function to collect dirt. During maintenance, the basket can be removed and conveniently cleaned outside the reactor. The invention provides a simple, cheap and rugged mechanical construction, which can be applied without empty space between tray and upper level of the packed bed.

The catalytic reactor for chemical reactions according to the invention comprises at least one catalyst bed and at least one distribution tray plate located above the catalyst bed within the catalytic reactor. The purpose and function on the distribution tray plate is to evenly distribute liquid, vapor and gas i.e.. fluid, across the cross-sectional area of the top of the catalyst bed. As described, using a distribution tray plate is well known. The catalytic reactor according to the present invention is special in that the distribution tray plate comprises a plurality of swirl distribution units which are simple, rugged and cheap, end effective in evenly distribution of fluid even with a short distribution space between the distribution tray plate and the top of the catalyst bed. The swirl distribution units comprise two main parts, an inner swirl chamber and an outer swirl chamber, both are hollow elongate chambers, their elongate direction is as close to vertical as is practical and feasible with regard to installation. The inner swirl chamber is cylindrical and thus has the shape of a pipe and is open in both the upper and the lower end. The outer swirl chamber, which at least partly encompasses the inner swirl chamber is not restricted by the function of the swirl distribution unit to the shape of a cylinder, but may have many different shapes, such as for example square, triangular, oval cylindrical an many more. Also the outer swirl chamber need not be coaxial with the inner swirl chamber, but it may be. Both the inner and the outer swirl chamber has at least one transfer opening each. The transfer openings allow for a fluid flow from the outer to the inner swirl chamber. Driven by pressure difference between the upper and the lower side of the distribution tray plate, process fluid flows from the upper side of the distribution tray plate, through the swirl distribution units and further to the lower side of the distribution tray plate and the catalyst bed. In the swirl distribution units, the process fluid flow in through the at least one transfer opening and also through the open lower end of the outer swirl chamber, from here it flows further to the corresponding at least one transfer opening of the inner swirl chamber. Because the transfer opening of the inner swirl chamber is angularly twisted relative to the corresponding transfer opening around the axis of the inner swirl chamber, a swirling motion relative to the axis of the inner swirl chamber is induced to the process fluid flow. From the transfer opening(s) of the inner swirl chamber, the process fluid flows down through the inner swirl chamber and out to the catalyst bed through the open lower end of the inner swirl chamber, while all the way keeping the induced swirling motion, which ensures a wide and even spread and distribution of the process fluid beneath each swirl distribution unit.

It is noted, that the open upper end of the inner swirl chamber is at least partly closed by the closed upper end of the outer swirl chamber which at least partly encompasses the inner swirl chamber.

In an embodiment of the invention, as already mentioned above, the outer swirl chamber may have a quadratic cross-sectional shape. This provides for a very cheap and easily manufactured swirl distribution unit, since both the inner and the outer swirl chamber may be manufactured from readily available tubes and a plate part to close the upper part of the outer swirl chamber. In this embodiment it may be beneficial to have four transfer openings in the outer swirl chamber as well as four corresponding transfer openings in the inner swirl chamber, since the circular/square cross-sectional shapes of the inner and the outer swirl chambers provides four intermediate passages/chambers between the inner and the outer swirl chambers. In another embodiment of the invention, the outer swirl chamber may have a triangular cross-sectional shape. In this embodiment it may be beneficial to have three transfer openings in the outer swirl chamber as well as three corresponding transfer openings in the inner swirl chamber, since the circular/triangular cross-sectional shapes of the inner and the outer swirl chambers provides three intermediate passages/chambers between the inner and the outer swirl chambers.

To provide even better fluid distribution and control of the distribution angle tailored to each application, the inner swirl chamber further has a nozzle ring fixed to the lower end of the inner swirl chamber in a further embodiment. By varying the angle of the nozzle ring throat, the angle of the distribution swirl may also be varied and adapted to the swirl distribution unit pattern on the distribution tray plate as well as the distance from the distribution tray plate to the top of the catalyst bed.

The transfer opening or openings in the outer swirl chamber may in an embodiment be an elongate aperture or cut-out in the outer swirl chamber. The elongation may run in a vertical direction, but angled directions may also apply.

In an embodiment, the transfer openings or openings in the inner swirl chamber may simply be cut-outs or carve outs of material in the open upper end of the inner swirl chamber. When assembled, the sides of the cut-outs, the inner sides of the outer swirl chamber and the closed upper end of the outer swirl chamber the forms the transfer opening(s) in the inner swirl chamber.

But the transfer openings in both inner and outer swirl chambers may also be holes. In yet a further embodiment of the invention, the swirl distribution units are arranged above and around the apertures in the distribution tray plate, but a part of the swirl distribution units also below the distribution tray plate, whereby the lower edge of the swirl distribution units may also act as a drip edge for the liquid to the catalytic bed arranged below the distribution tray plate.

In an embodiment of the invention, the catalytic reactor is a hydroprocessing reactor.

FEATURES OF THE INVENTION

1. Catalytic reactor for chemical reactions comprising a catalyst bed and further comprising a distribution tray plate located above the catalyst bed within the catalytic reactor for even distribution of liquid, vapour and gas across the cross sectional area of the top of the catalyst bed, said distribution tray plate comprises a plurality of swirl distribution units fixed to the distribution tray plate above and around apertures in the distribution tray plate, the swirl distribution units comprise

• an elongate, cylindrical inner swirl chamber, with at least one transfer opening for passing of fluid

• an elongate outer swirl chamber at least partially encompassing the inner swirl chamber and with at least one transfer opening for passing of fluid, corresponding and in fluid connection to the transfer opening in the inner swirl chamber, wherein the inner swirl chamber is open at its upper and lower ends and the outer swirl chamber is open at its lower end, the swirl distribution unit is adapted to allow fluid flow from the at least one transfer opening in the outer swirl chamber via the corresponding transfer opening in the inner swirl chamber and further out through the lower open end of the inner swirl chamber; the transfer opening in the inner swirl chamber is angularly twisted relative to the corresponding transfer opening in the outer swirl chamber around the axis of the inner swirl chamber, thereby inducing a swirling motion to the fluid flow. 2. Catalytic reactor according to feature 1 , wherein the outer swirl chamber has a quadratic cross-sectional shape. 3. Catalytic reactor according to feature 1 or 2, wherein the inner swirl chamber and the outer swirl chamber has four transfer openings each.

4. Catalytic reactor according to feature 1 , wherein the outer swirl chamber has a triangular cross-sectional shape.

5. Catalytic reactor according to feature 1 or 4, wherein the inner swirl chamber and the outer swirl chamber has three transfer openings each.

6. Catalytic reactor according to any of the preceding features, wherein the inner swirl chamber further has a nozzle ring fixed to the lower end of the inner swirl chamber.

7. Catalytic reactor according to any of the preceding features, wherein the at least one transfer opening in the outer swirl chamber is an elongate aperture or cut-out oriented with its longitude direction along the axis of the outer swirl chamber.

8. Catalytic reactor according to any of the preceding features, wherein the at least one transfer opening in the inner swirl chamber is a cut-out in the upper end of the inner swirl chamber or a hole located in the upper end of the inner swirl chamber.

9. Catalytic reactor according to any of the preceding features, wherein the at least one transfer opening in the inner swirl chamber is formed between the edges of a cut-out in the upper end of the inner swirl chamber and the outer swirl chamber wall and closed upper end. 10. Catalytic reactor according to any of the preceding features, wherein the inner swirl chamber is concentric with the outer swirl chamber.

11. Catalytic reactor according to any of the features 1 - 10, wherein the inner swirl chamber is eccentric with the outer swirl chamber.

12. Catalytic reactor according to any of the preceding features, wherein the inner swirl chamber is made from steel pipe and the outer swirl chamber is made from steel pipe or plate, or steel pipe and plate.

13. Catalytic reactor according to any of the preceding features, wherein a part of the swirl distribution unit is arranged below the distribution tray plate.

14. Catalytic reactor according to any of the preceding features, wherein said catalytic reactor is a hydroprocessing reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further illustrated by the accompanying drawings showing examples of embodiments of the invention.

FIG. 1 shows an isometric side view of the swirl distribution unit according to an embodiment of the invention.

FIG. 2 shows an isometric side view of the inner swirl chamber according to an embodiment of the invention.

FIG. 3 shows an isometric vertical cut side view of the swirl distribution unit according to an embodiment of the invention. Fig. 4 shows an isometric vertical cut bottom view of the swirl distribution unit according to an embodiment of the invention.

Fig. 5 shows an isometric vertical partial cut side view of the nozzle ring according to an embodiment of the invention.

Fig.6 shows three principle bottom views of the swirl distribution unit according to different embodiments of the invention.

POSITION NUMBERS

01. Swirl distribution unit.

02. Inner swirl chamber. 03. Outer swirl chamber.

04. Nozzle ring. 05. Transfer opening.

DESCRIPTION OF THE DRAWINGS

Some specific embodiments of the invention will be explained in more detail in the following with reference to the drawings as seen on Fig. 1 to Fig. 6.

A catalytic reactor (not shown) comprises a liquid distribution tray with a distribution tray plate with a plurality of apertures on a uniform square or triangular pitch (not shown, known art). One swirl distribution unit 01 is fitted down through or above and around each aperture.

The swirl distribution unit 01 design concept is shown in FIG. 1. The outer swirl chamber 03 encompasses the upper and some of the lower part of the inner swirl chamber 02, whereby only two of the transfer openings 05 in the outer swirl chamber are visible, whereas the transfer openings in the inner swirl chamber is hidden. In the shown embodiment, the outer swirl chamber is made from a square tube with an upper end closed by a plate part. The dimension of the square tube is adapted to snug fit the inner swirl chamber outer side to the inner side of the outer swirl chamber. The inner swirl chamber is seen in more detail in Fig. 2, showing also the transfer openings of the inner swirl chamber which in this embodiment are four carved out parts of the upper end of the inner swirl chamber. When assembled, the carved-out parts along with the sides and closed end of the outer swirl chamber forms the transfer openings in the inner swirl chamber, as seen more clearly in Fig. 3 and in Fig. 4. Fig. 3 (as well as Fig. 5) also clearly shows the nozzle ring 04 fixed to the lower end of the cylindrical inner swirl chamber. The cross sectional cut of the nozzle ring shows the angled face of the upper side of the nozzle ring, which as explained earlier can control the angle of the swirl cone of the fluid exiting the swirl distribution unit. The swirling motion of the fluid is induced by the angular rotation of corresponding transfer openings in the outer and inner swirl chambers. This is seen in Fig. 4 and in a principle drawing also in Fig. 6.

In Fig. 6, three different embodiments are shown in a principle drawing, bottom view. In all three embodiments, the inner swirl chamber has a circular cross section. In the first embodiment (embodiment furthest left in the drawing) also the outer swirl chamber is cylindrical and thus has a circular cross section. The inner and outer swirl chamber are assembled in a linear, vertical assembly thereby creating one inner passage between the inner and the outer swirl chamber. As can be seen the transfer opening in the inner swirl chamber is significantly angularly twisted relatively to the transfer opening in the outer swirl chamber. Thus, when fluid flows in the inner passage from the transfer opening in the outer swirl chamber to the transfer opening, a swirl is induced as symbolized by the arrow. In the second embodiment (middle in the drawing) the outer swirl chamber has an oval cross section (which could be achieved by pressing a tube with a circular cross section), the narrow inner part adapted to fit the outer circumference of the inner swirl chamber. This provides two inner passages between the inner and the outer swirl chamber, and with two sets of corresponding transfer openings in the inner and outer swirl chamber, a swirl is induced to fluid flowing through the swirl distribution unit as symbolized by the arrows. Same principle applies to the third embodiment (furthest left in drawing, Fig. 6), only here the outer swirl chamber has a triangular cross section, which provides for three inner passages between the inner and the outer swirl chamber, when the inner sides of the outer swirl chamber are adapted to fit the outer circumference of the inner swirl chamber cylinder. Accordingly, three sets of corresponding transfer openings in the inner and the outer swirl chamber provides an induced swirl to the fluid flowing through the swirl distribution unit as symbolized by the arrows.