Feedstock injection device of an FCC unit

Abstract

The invention relates to an injection device (10) for atomizing a liquid into droplets using a gas, comprising a hollow tubular body (12) having a longitudinal direction (X). An inner wall (13) defines a first region, referred to as contact region (Z1), and a second region (Z2). The body includes: —at least two inlet ports (14; 16) for injecting liquid and an inlet port for injecting gas, all of said ports extending to the first region (Z1); —at least one outlet port (18), located downstream of the first and second regions, for discharging the atomized liquid. The body (12) has an inner cross-section that varies continuously or constantly over the entire length thereof. Between regions (Z1) and (Z2), the inner wall (13) includes at least one baffle (261) which is shaped such that in each plane running perpendicularly to the longitudinal direction of the body containing said baffle, the baffle reduces an inner cross-section of the body over the entire periphery of the inner wall (13).

Claims

1. An injection device configured to atomize a liquid into droplets using a gas, comprising a hollow tubular body extending in a longitudinal direction (X) and of which an internal wall defines a first zone referred to as a first contact zone (Z1) and a second zone (Z2) situated downstream of the first zone with respect to a direction in which the liquid and the gas circulate inside the body, the latter having: at least two inlet openings opening into the first contact zone (Z1), to inject a liquid into the first zone, the said openings each having an axis oriented in such a way that the streams of liquid emanating from the said openings converge on a longitudinal line (X) extending inside the body, an inlet opening into the first contact zone (Z1), so as to inject an atomizing gas into the first contact zone, at least one outlet orifice situated downstream of the first and second zones, for removing the atomized liquid from the body, characterized in that the body has an internal cross section that varies continuously or is constant along its entire length and the internal wall of the body is provided, between the first and the second zones, with one or more chicanes configured so that, in each plane perpendicular to the longitudinal direction of the body containing the one or more chicanes, the one or more chicanes reduce an internal cross section of the body over the entire periphery of the internal wall, wherein the internal wall is provided with a plurality of disjointed chicanes, wherein more than one adjacent chicanes have heights, measured perpendicular to the longitudinal direction of the body, which are non-zero and different, and wherein in the longitudinal direction of the body, the heights of the adjacent chicanes increase up to a maximum and to decrease.

2. The injection device according to claim 1, wherein the internal wall is provided with a single chicane extending over a length, in the longitudinal direction, at least equal to a maximum internal dimension of the body measured perpendicular to the longitudinal direction.

3. The injection device according to claim 2, wherein the single chicane has an irregular profile in the longitudinal direction of the body.

4. The injection device according to claim 1, wherein at least one chicane is spaced away from at least one other chicane in the longitudinal direction of the body.

5. The injection device according to claim 1, wherein the one or more chicanes define a wall projecting from the internal wall and one edge of which is secured to the internal wall.

6. The injection device according to claim 5, wherein the wall defined by the one or more chicanes exhibits a free edge distant from the internal wall.

7. The injection device according to claim 5, wherein the internal wall is toothed or crenelated.

8. The injection device according to claim 5, wherein the one or more chicanes have orifices passing right through it.

9. The injection device according to claim 1, wherein the one or more chicanes have a height, measured perpendicular to the longitudinal direction of the body, that is non-zero and equal to at most ½ of a maximum internal dimension of the body perpendicular to the longitudinal direction of the body.

10. The injection device according to claim 1, wherein the one or more chicanes have, on the side of the inlet openings, a curved face arranged so as to direct a fluid impinging on the face towards the inside of the body.

Description

(1) The invention is now described with reference to the appended, non-limiting drawings, in which:

(2) FIG. 1 is a schematic depiction in longitudinal section of an injection device according to one embodiment of the invention;

(3) FIG. 2a is a view in section on AA of a chicane of FIG. 1, according to one embodiment;

(4) FIGS. 2b, 2c and 2d are views in section similar to those of FIG. 2a according to other embodiments;

(5) FIG. 3 partially depicts a longitudinal section of an injection device according to another alternative form;

(6) FIG. 4 partially depicts a longitudinal section of an injection device according to another alternative form;

(7) FIG. 5 depicts a face-on view (along the longitudinal axis X) of several chicanes according to another alternative form;

(8) FIG. 6 depicts a face-on view (along the longitudinal axis X) of one and the same chicane according to another alternative form, and views in section in two distinct directions A′A and B′B which are perpendicular to the longitudinal direction;

(9) FIGS. 7 and 8 partially depict views in longitudinal section of chicanes having free edges of different shapes,

(10) FIG. 9 partially depicts a longitudinal section of an injection device according to yet another alternative form.

(11) In the various figures, elements that are identical bear the same references.

(12) FIG. 1 schematically depicts an injection device 10 which has a hollow tubular body 12 which extends in a longitudinal direction X.

(13) The body 12 comprises an internal wall 13 which defines a first zone Z1 referred to as contact zone, and a second zone Z2 situated downstream of the first zone Z1 with respect to a direction in which the liquid and the gas circulate inside the body (in this instance from left to right in FIG. 1).

(14) The injection device 10 further comprises: an inlet opening 14 opening into the first zone Z1, so as to inject an atomizing gas into the first zone, a second inlet opening 16 opening into the said first zone Z1, so as to inject a liquid into the first zone, a third inlet opening 17 opening into the first zone Z1, likewise so as to inject a liquid into the first zone, at least one outlet orifice 18 situated downstream of the first and second zones, for removing the atomized liquid from the body,

(15) The first opening 14 is thus intended to be connected to a gas supply pipe, while the openings 16 and 17 are intended to be connected to a liquid supply pipe. As described in document WO2015/170034A1 (incorporated by reference), a single liquid supply pipe may be provided, which supplies a chamber communicating with the openings 16 and 17, or one supply pipe per opening may be provided.

(16) The second and third openings 16, 17 each have an axis 16′, 17′.

(17) These axes 16′, 17′ are oriented in such a way that the streams of liquid emanating from the openings 16, 17 converge on a longitudinal line extending inside the body, here the longitudinal axis X. In this example, the axes 16′, 17′ extend perpendicular to the longitudinal direction of the body and are arranged in such a way that their axes 16′, 17′ intersect at one single same point I on the longitudinal axis X. The invention is not restricted to this embodiment provided that the streams or jets of liquid emanating from the openings converge towards one another and impinge on a longitudinal line internal to the body.

(18) Inside the body 12, the fluids circulate from the inlet openings 14-17 towards the outlet orifice 18.

(19) Here, the first zone Z1 and the second zone Z2 take the form of a straight internal pipe connecting the first inlet opening 14 to the outlet orifice 18 in an axial direction of the said body. This internal pipe in this example has a constant internal diameter. The invention is not, however, limited by this embodiment. The internal cross section of this pipe (in other words of the body) could vary continuously or be constant over the entire length of the pipe (i.e. of the body), without, however, being circular.

(20) In the embodiment depicted, the body 12 is a cylinder, in other words the internal wall 13 here is cylindrical, its axis coinciding with the longitudinal direction X of the body. It will be noted that the body 12 is produced in a single piece. Nevertheless, it could be produced in two or more parts welded together. The opening 14, on the one hand, and the openings 16, 17 on the other, each accept a respective element 15, 19 for the introduction of the fluids. It will be noted that these elements do not project into the body. This arrangement may be provided for a body that is non-cylindrical.

(21) The jets of liquid entering via the openings 16 and 17 are sprayed towards one another and strike one another substantially at the point I. The burst jets of liquid are carried away in the form of droplets by a stream of atomizing gas introduced at high speed via the opening 14. Atomization of the liquid takes place in two stages. A first part of the atomization occurs at the point I by impact of the jets with one another. The jets of liquid thus burst are sheared by the incoming gas by the gas introduced through the opening 14. The second part of the atomization occurs at the reduced-diameter outlet orifice 18, where the narrowing in diameter accelerates the fluids.

(22) In the example depicted, the two openings 16, 17 face one another (their axes 16′, 17′ coincide). However, it is possible to conceive of a higher number of openings for the liquid, for example 3 or 4 or even more, arranged in such a way that the jets of liquid strike one another at the point I on the axis X in the stream of gas entering via the opening 14. In general, the liquid is thus injected radially into the body, which has no target.

(23) According to the invention, the internal wall 13 of the body is also provided, between the first zone Z1 and the second zone Z2, with at least one chicane 26i (where i, the number of chicanes, is a non-zero whole number). Because this chicane locally reduces the diameter of the internal wall 13, it disrupts the movement of the fluid, encouraging mixing. In particular, the presence of a chicane makes it possible to avoid the formation of a film of liquid on the wall by bringing the liquid back into the axis of the stream of gas.

(24) One or more chicanes may be provided. The injection device 10 may thus comprise a single chicane 26.sub.1, as depicted in FIG. 2a, situated at the line of section A-A of FIG. 1. This chicane 26.sub.1 takes the form of a solid collar extending over the entire periphery of the internal wall 13. Here, the chicane 26.sub.1 defines a wall extending at right angles to the longitudinal direction X.

(25) FIGS. 2 to 9 depict other embodiments which differ from those previously described in terms of the number and/or shape of the chicanes. In these figures, the chicanes are denoted by the reference “26i” or “J26i”, the suffix “i”, a non-zero whole number, representing the number of chicanes, embodiments differing from those previously described being identified by J (a whole number from 1 to 6 in the examples), the alternative forms of one and the same embodiment being identified by the prime (′) and double prime (″) symbols.

(26) FIG. 2b is a view in cross section of a chicane according to another embodiment, in which the chicane 126.sub.1 is perforated. Orifices 27 pass right through it, allowing the passage of fluid. This arrangement makes it possible to improve the dispersion of the fluid downstream of the chicane, causes less disruption to the flow of the fluid, while at the same time re-orientating this fluid towards the axis of the body 12.

(27) FIGS. 2c and 2d are views in cross section of a chicane according to another embodiment, in which the chicane 226.sub.1, 226′.sub.1 has a free edge 227, 227′ respectively, distant from the internal wall 13 which is either toothed (in the case of the chicane 226.sub.1) or crenellated (in the case of the chicane 226′.sub.1). These arrangements have a similar effect to that of FIG. 2b.

(28) In the example depicted in FIG. 1 and FIGS. 2a-2d, the chicanes take the form of planar walls perpendicular to the longitudinal direction X. In other words, one edge of the wall of each chicane is thus secured to the internal wall 13 along a line extending in a plane perpendicular to the longitudinal direction of the said body.

(29) These walls could also be curved. Thus, FIG. 3 is a partial depiction in axial section of the injection device 10 provided with a chicane 326.sub.1 that is curved, notably in the direction of the central longitudinal axis of the body 12. Here, the concavity of the chicane is orientated towards the outlet orifice 18. Nevertheless, provision could be made for it to be orientated in the opposite direction. Provision could also be made for one and the same chicane to have parts that are curved in opposite directions.

(30) One single chicane is depicted in the example of FIGS. 1, 2a-2d, 3, though other chicanes 26i, 126i, 226i, 226′i, 326i spaced apart in the direction X could nevertheless be provided.

(31) The embodiment of FIG. 4 shows 5 chicanes 426.sub.1, 426.sub.2, 426.sub.2, 426.sub.4, 426.sub.5, spaced apart in the longitudinal direction X of the body 14. It will be noted that each chicane has a height that is constant over its entire periphery (as in the example of FIG. 2a), but that adjacent chicanes have different heights. In the example, the heights of the chicanes increase until they reach a maximum and to decrease.

(32) Whatever the embodiment, the chicane or chicanes may have a radial dimension or height (perpendicular to the longitudinal direction X) that is relatively small, for example less than ⅛.sup.th of the diameter of the internal wall 13, or even of the order of 1/10.sup.th of this diameter, but not zero. This height may have a value in a range defined by any combination of the aforementioned limits.

(33) This height may differ from one chicane to another, as in the embodiment of FIG. 4. This height may also vary along the periphery of a chicane, as in the examples of FIGS. 2c, 2d and 5. In FIG. 5, the chicane 526.sub.1 has 4 notches 527 where its height is reduced, but non-zero.

(34) It will be noted that, whatever its shape (curved or planar), a chicane (or the tangent thereto at the point at which it meets the internal wall 13 of the body) may define a predetermined angle with respect to a plane orthogonal to the longitudinal direction of the body (see FIGS. 3, 6, 7(b) and 8(a)). This angle may be variable for one and the same chicane 226″.sub.1, as visible in FIG. 6.

(35) The chicane or chicanes inclined in this way may be inclined in the direction of the outlet orifice 18.

(36) Whatever its shape (curved or planar), the free edge of a chicane (the opposite edge to the edge secured to the internal wall of the body) may have a face 28a of rounded shape (FIG. 7(a)), a face 28′a that is bevelled (FIG. 7(b)), two faces 28a, 28b with a rounded shape (FIG. 8a)) or two faces 28′a, 28′b with a bevelled shape (FIG. 8(b)).

(37) When just one face is provided, it is preferably situated on the side of the mixing zone Z1 in the longitudinal direction X.

(38) The aforementioned non-zero thickness (or length) of the chicanes, measured in the longitudinal direction X of the body is, for example, at most 16 to 35 mm.

(39) It will be noted that the chicane or chicanes described with reference to FIGS. 1, 2a-2d, and 3 to 8 define a (planar or non-planar) wall of which the dimension in the longitudinal direction X is less than the dimension in a direction perpendicular to the longitudinal direction. In the embodiment of FIG. 9, the chicane no longer defines a wall insofar as the length (in the longitudinal direction X) is greater than its dimension perpendicular to the longitudinal direction X.

(40) In the embodiment depicted in FIG. 9, the internal wall 13 is thus provided with a single chicane 626.sub.1 extending over a length, in the longitudinal direction, at least equal to a maximum internal dimension of the body measured perpendicular to the longitudinal direction, or in other words to the internal diameter of the body in this example. It will be further noted that the chicane 626.sub.1 has an irregular profile in the longitudinal direction of the body. Thus, its height is variable in the X direction. The shape of this profile may be tailored to suit: it may be similar to the overall profile of the 5 chicanes in FIG. 4 or form undulations as depicted in FIG. 9. Furthermore, the height of the chicane could also be variable in each transverse section of the chicane.

(41) The chicane or chicanes are arranged between the first and second zones Z1, Z2. Typically, the second zone has a length (in the longitudinal direction X) 2 to 10 times greater than the length of the first zone. The chicane or chicanes, notably the first chicane, may be situated at a distance “1” from the axis of the openings 16, 17 of the maximum internal dimension of the internal cross section of the body (in this instance the diameter) or even less than the maximum internal dimension of the internal cross section of the body, at the level of the first zone, for example at a distance corresponding to ¾ of this maximum internal dimension (for the sake of clarity, the figures are not drawn to scale).

(42) The chicanes described hereinabove may be produced as one piece with the body 12, for example by moulding or machining, or may be added-on elements which are fixed, for example welded, held between flanges, or the like. When several chicanes are present, they may be identical or different, it being possible to combine the various shapes and arrangements of chicanes described hereinabove.