KR20070019995A - Downcomers for slurry bubble column reactors - Google Patents

Abstract

A downcomer (61) for use in a slurry bubble column reactor (60) comprises: an upper part (62) including a slurry inlet (66) through which slurry can enter the downcomer (61), gas separation means (65) arranged to separate gas bubbles from the slurry, and a gas outlet through which the separated gas can escape; an elongate, tabular-shaped intermediate section (63) which extends vertically in use and through which slurry can pass downwards; and a lower portion (64) which has a slurry outlet (71). The slurry outlet (71) is defined by a wall (69) which is inclined relative to the longitudinal axis of the intermediate section (63). ® KIPO & WIPO 2007

Description

DOWNCOMERS FOR SLURRY BUBBLE COLUMN REACTORS}

The present invention relates to a downcomer for a slurry bubble column reactor.

The downcomer is used to provide a more suitable and uniform catalyst particle body in the vertical direction of the slurry phase, and slurry bubbles so as to obtain a more uniform temperature distribution in the slurry bubble column reactor (SBCR). Used in column reactors. Generally, the downcomer is a tubular structure located vertically in the slurry bubble column reactor, and the downcomer is provided with gas venting means and means for restricting entry of rising gas bubbles into the bottom of the downcomer structure.

International patent publication WO 98/50494 discloses a downcomer in which the gas discharge zone is located on top of the downcomer. A conical baffle below the bottom of the downcomer prevents upwardly moving gas bubbles from entering the downcomer.

EP 0674610 discloses a downcomer with both ends open and completely submerged in a slurry phase. The bottom end of the downcomer is shielded by a baffle device that diverts the gas bubbles from the bottom of the slurry bubble column reactor to prevent gas bubbles from entering the bottom end of the downcomer. The baffle device can take a conical shape similar to the shape of WO 98/50494.

It is an object of the present invention to obtain a more uniform vertical distribution of catalyst particles in a slurry bubble column reactor.

According to the invention, as a downcomer for use in a slurry bubble column reactor, a slurry inlet configured to allow a slurry to pass through and enter a downcomer, and a gas outlet configured to allow the separated gas to leak out A top portion comprising an elongated tubular intermediate zone configured to extend vertically in use and to allow the slurry to pass through and to the bottom, and a lower portion having a slurry outlet, wherein at least a portion of the slurry outlet is The slurry outlet is defined by a wall inclined with respect to the longitudinal axis and the slurry outlet is an orifice defining an aperture of the intermediate zone in the wall, wherein the hole is a slurry outlet in which gas moves upwards in use. Duck in a plane perpendicular to the axis of the intermediate zone so that entry into the downcomer through A downcomer is provided for use in a slurry bubble column reactor that is the region of the opening from the piece to the intermediate zone and is less than two thirds of the intermediate zone cross sectional area.

Preferably, the upper portion comprises separation means arranged to separate the gas bubbles from the slurry.

The hole can be regarded as the surface area under the downcomer, which is illuminated by rays traveling downwardly from the interior of the downcomer in a direction parallel to the axis of the intermediate zone, the surface being perpendicular to the axis of the intermediate zone.

Preferably, the inclined portion takes a smooth, curved shape and can be part of the tube bend.

The outlet is formed by a frusto-conical wall zone, such that the outlet has an area smaller than the cross sectional area of the intermediate zone. The perimeter of the outlet can be inclined or parallel at an oblique angle with respect to the axis of the intermediate zone. The outlet may be biased from the intermediate zone when viewed in the axial direction of the intermediate zone.

Preferably, any substantial portion of the downcomer wall takes a steeper slope than the angle of repose of the catalyst particles under effective conditions to prevent the catalyst from being formed at that location.

Preferably, the intermediate zone comprises means for restricting the passage of gas upwards into the intermediate zone in use. Preferably, the means for limiting the passage of gas comprises a disc disposed horizontally inside the intermediate zone, said disc covering at least 20% of the intermediate zone cross sectional area.

Preferably, when the slurry bubble column reactor is in use, the middle zone comprises means for collecting gas bubbles in the slurry. Preferably, the means for collecting the gas bubbles comprises a tube with an extended edge at the lower end. Preferably, the tube extends to the top of the downcomer.

The present invention extends to a reactor such as a slurry bubble column reactor comprising one or more downcomers as described above. Preferably, the vertical length of the downcomer is in the range of 30-120% of the intended depth of the slurry in the reactor in use. Preferably, a gas phase is present above the slurry and the gas outlet from the upper portion is in communication with the gas phase.

The present invention extends to the process of using such a reactor to carry out a Fischer-Tropsch synthesis reaction.

1 to 5 show five alternative embodiments of the lower end of the downcomer according to the present invention.

6 shows the embodiment of FIG. 1 on an enlarged scale.

7 is a cross-sectional view taken along the cutting line AA in FIG. 6.

8 is a vertical sectional view through a reactor including a downcomer according to the present invention.

9 is a cross-sectional view taken along the line BB of FIG. 8.

10 is a graph showing the effect of gas velocity on downcomer operation.

11, 12, and 13 illustrate alternative shapes for the downcomer exit.

FIG. 14 is a graph showing the shape effects for the alternative in FIGS. 11, 12, and 13.

FIG. 15 is a graph showing the communication effect of the gas space and the downcomer above the slurry phase. FIG.

FIG. 16 is a graph similar to FIG. 10, but showing the case of having particles in the liquid; FIG.

17, 18, and 19 are graphs showing catalyst condensation profiles at various gas velocities.

The present invention can be implemented in various ways, and various embodiments are described by way of example with reference to the accompanying drawings.

The embodiment shown in FIG. 1 represents one detailed experimental apparatus illustrating the principles and operation of the present invention. It should be understood that such embodiments may not be suitable for full size industrial applications.

The lower portion of the downcomer 11 is formed from a 7.62 cm (3 inch) tube having a bend at the bottom that defines an orifice 13 set at an angle of 45 ° to the axis of the tube. In practice, such a design works well.

In FIG. 2, the tube forming the downcomer 21 has a diameter of 127 mm (5 inches). The tube has an elbow joint 22 defining an orifice 23 parallel to the axis of the tube. Even if the flow rate through the downcomer is low, such a design works well in practice.

The design shown in FIG. 3 is similar to the design in FIG. 2 but additionally includes a disk 34 about 50 cm above the orifice 33 and inside the downcomer 31. The disk 34 occupies about half of the cross-sectional area of the downcomer 31. In addition, this design works well, but when the disk 34 is replaced with a small disk that occupies about a quarter of the cross-sectional area and positioned 150 cm above the orifice 23, the performance of the downcomer becomes unsatisfactory.

The downcomer 41 shown in FIG. 4 is also similar to the downcomer of FIG. 2, but is connected to a tube 45 extending upwardly to open up from the top of the slurry phase and located on the inverting funnel located above the orifice 43. inverted funnel) (44).

The downcomer 51 shown in FIG. 5 is similar to the downcomer in FIG. 2, but in this case the truncated cone 54 in which the lower part defines a smaller orifice 53 parallel to the axis of the tube. Terminates in

Both embodiments shown in FIGS. 4 and 5 work well.

6 and 7 the concept of a hole defined by an orifice is expanded. As described in connection with FIG. 1, the downcomer 11 terminates at the bend 12 defining the orifice 13. The oval shape 15 outlines the orifice 13, while the outline of the tube is shown as circle 14 in FIG. 7. The area 16 delimited by the two regions of the circle 14 and the elliptical shape 15 is a hole. 2, 3, 4, 5, 8, 9, 12, and 13 it can be seen that the hole has a value of zero.

8 and 9 show the downcomer 61 extending vertically in the slurry bubble column reactor 60. In practice, it can be appreciated that there are usually several downcomers in the reactor.

The downcomer 61 includes an upper portion 62, an intermediate region 63, and a lower portion 64.

The upper portion 62 is about 260 cm high, the top is open and has an inner diameter of about 11.2 cm. The bottom 78 cm of the upper portion 62 has an increased inner diameter of 21 cm and constitutes the gas removal zone 65. Degassing zone 65 includes a series of slurry inlets 66 inside the downcomer located about 50 cm above the bottom of the degassing zone 65. The area of the slurry inlet 66 is 1.9 times the cross-sectional area of the gas removal zone 65 and 6.7 times the cross-sectional area of the middle zone 63 of the downcomer 61.

The middle section 63 is a tube having a height of 1200 cm and a diameter of 11.2 cm.

The lower portion 64 comprises a tube 68 having a diameter of 11.2 cm and a bend 69 terminating at an orifice 71 parallel to the axis of the downcomer 61. In total, the lower portion has a height of about 97 cm.

The reactor 60 has a height of about 1600 cm and an inner diameter of about 50 cm and contains the slurry liquid 72 up to a height 73 of about 1550 cm, which is below the open top height of the downcomer 61. The open top of the downcomer is represented by the gas space 74 above the liquid 72. At the top of the reactor 60 is a gas outlet 75.

Near the bottom (not shown) of the reactor 60 is a gas inlet 76 and a gas distributor 77. The relative position of the downcomer 61 and the gas inlet are shown in FIG. 9. Reactor 60 further has a slurry outlet (not shown).

The invention is further illustrated in the following examples. The device used is the device described with reference to FIGS. 8 and 9. In a commercial installation, it should be understood that the downcomer may have a size other than the downcomer referenced in the following examples.

Example  One

Effect of gas velocity

The column with the downcomer shown in FIGS. 8 and 9 is filled with water, air is injected near the reactor bottom, and the surface gas velocity, u _g , changes. The expanded liquid height, Δh _top , above the top of the slurry inlet region remains nearly constant. In the table below, the corresponding liquid velocity in the downcomer, u _1, is recorded. The pressure difference inside and outside the downcomer, ΔP, is further included to indicate the relationship between this parameter and the liquid velocity. The results are shown in Table 1 and also graphically shown in FIG. 10.

TABLE 1

u _g (m / s) Δh _top (m) u ₁ (m / s) ΔP (mmH ₂ O) 0.107 1.25 1.25 392 0.217 1.25 1.18 331 0.302 1.25 1.03 211

The results indicate that the efficiency of the downcomer decreases with increasing gas velocity. However, it should be borne in mind that the function of the downcomer is to reduce the axial catalyst concentration profile. This profile decreases with increasing gas velocity. Therefore, it is most important that the downcomer has good efficiency at low gas velocities.

Example 2

Other available Downcomer  Exit shape

The downcomer exit zone helps to prevent gas bubbles from entering the downcomer. Various other shapes are possible in addition to the 90 ° bending shown in FIGS. 8 and 9. A short length (6.6 m high) column as shown in FIGS. 8 and 9 is used for a 5 inch diameter downcomer, and three other possible shapes were studied. Three

There is no bending at the slurry outlet, but the outlet diameter is reduced such that the outlet cross section is reduced by 50%;

135 ° bend, top half of slurry outlet area plugged;

-90 ° bending, funnel covering half of the cross-sectional area with a gas collection device inside. The shapes are shown as in FIGS. 11, 12, and 13.

The results are shown in FIG. 14 and show no substantial difference in downcomer performance for the various options.

Other options for downcomer outlets that worsen downcomer performance have also been tested. In this test, the ΔP measurements are used to indicate performance, not flow meters. The tested structure

No bending at the slurry outlet and no decrease in outlet diameter;

The case has a hole area greater than FIG. 16 and a 45 ° bend.

The experimental results for the last option are shown in Table 2 below (ΔP values close to zero indicate no liquid flow (or very small) inside the downcomer).

TABLE 2

Δh _top (m) u _g (m / s) ΔP (mmH ₂ O) 0.9-1.2 0.25-0.3 1.18 1.2 ~ 1.4 0.1-0.2 1.36 1.2 ~ 1.4 0.2 ~ 0.25 1.33

Example  3

Effect of the upper part of the degassing zone

EP 0674610 uses a downcomer completely submerged in a slurry phase. In this embodiment, the downcomer with the slurry inlet is compared to the unlocked downcomer, with the slurry inlet on the side of the gas removal zone. A column with the downcomer shown in FIGS. 8 and 9 is used except that only the downcomer zone below the slurry inlet is in use. The expanded liquid height above the top of the slurry inlet region, Δh _top, remains nearly constant. Table 3 below shows the corresponding liquid velocity, u ₁ , in the downcomer. The results shown in Table 3 are compared to the results obtained with the downcomer (i.e., the present invention) with the slurry inlet on the side of the gas removal zone but not submerged in FIG.

TABLE 3

u _g (m / s) Δh _top (m) u ₁ (m / s) 0.106 One 0.98 0.108 1.05 0.98 0.208 1.25 0.92 0.312 1.2 0.847

Example  4

Effect of Catalyst Concentration Profile

Columns with downcomers shown in FIGS. 8 and 9 are further used in this embodiment. In addition to water, the column is now filled with particles. The particles used are made of silicon carbide (SiC) and have an average particle size of about 75 μm. The concentration of the particles is about 200 g / l. The expanded liquid height above the top of the slurry inlet region, Δh _top, remains nearly constant. The corresponding liquid velocity, u ₁ , in the downcomer is shown in Table 4 and FIG. 16.

TABLE 4

Δh _top (m) u _g (m / s) u ₁ (m / s) 1.1 0.101 1.4 1.2 0.199 1.32 1.1 0.281 1.18

At each gas velocity, a sample of slurry was withdrawn from the column to determine the catalyst concentration. The downcomer inlet was then sealed and the experiment repeated for all three speeds. The catalyst concentration profiles in the experiments with and without downcomers in use are shown for various gas velocities in FIGS. 17, 18, and 19. The figure clearly shows the effect of the downcomer. If there is a downcomer in use, the catalyst concentration is more uniform throughout the column than there is no downcomer in use. (Note: the numbers on the x-axis of Figures 17, 18, and 19 represent the distance above the gas distributor. A negative number means that the sample is retracted below this height).

Claims (23)

As a downcomer for use in a slurry bubble column reactor, A slurry inlet configured to allow the slurry to pass through and enter the downcomer, and a gas outlet configured to allow the separated gas to leak out, configured to extend vertically in use and allow the slurry to pass through downward An upper portion comprising an elongated tubular intermediate zone below the upper portion, and a lower portion below the intermediate zone having a slurry outlet zone, wherein the slurry outlet zone comprises at least a portion of the slurry outlet zone longitudinal axis of the intermediate zone. The slurry outlet zone is terminated at an orifice defining an aperture of the intermediate zone at the wall, the aperture being defined by a wall that is inclined to In a plane perpendicular to the axis of the middle zone so that entry into the downcomer through the exit is restricted Up from the orifice is the area of the opening to the middle section down keomeo for use in a slurry bubble column reactor, characterized in that less than two-thirds of the mid-section cross sectional area. The method of claim 1, Downcomer for use in a slurry bubble column reactor, the upper portion comprising separation means arranged to separate gas bubbles from the slurry. The method according to claim 1 or 2, Downcomer for use in a slurry bubble column reactor, wherein said aperture represents less than 50% of the cross-sectional area of the middle zone. The method of claim 3, Downcomer for use in a slurry bubble column reactor, wherein said aperture represents less than 25% of the cross-sectional area of the middle zone. The method of claim 4, wherein Downcomer for use in a slurry bubble column reactor, wherein said aperture represents 0% of the cross-sectional area of the middle zone. The method according to any of the preceding claims, Downcomer for use in a slurry bubble column reactor, characterized in that the geometrical projection of the lower portion in a plane perpendicular to the axis of the middle zone represents less than 110% of the cross section of the middle zone. The method according to any of the preceding claims, The outlet is formed by a frusto-conical wall zone such that the outlet has an area smaller than the cross sectional area of the intermediate zone. The method according to any of the preceding claims, Downcomer for use in a slurry bubble column reactor, characterized in that the circumference of the outlet is inclined at an oblique angle with respect to the axis of the intermediate zone. The method according to any one of claims 1 to 7, Downcomer for use in a slurry bubble column reactor, characterized in that the perimeter of the outlet is parallel to the axis of the intermediate zone. The method according to any of the preceding claims, Downcomer for use in a slurry bubble column reactor, characterized in that the outlet is biased from the intermediate zone when viewed in the axial direction of the intermediate zone. The method according to any of the preceding claims, Any substantial portion of the downcomer wall, under effective conditions, takes a steeper slope than the angle of repose of the catalyst particles, preventing formation of the catalyst at that location. Downcomer. The method according to any of the preceding claims, Downcomer for use in a slurry bubble column reactor, wherein the intermediate zone comprises means for restricting gas passing upwards within the intermediate zone when in use. The method of claim 12, Means for limiting gas passage include discs disposed horizontally within the intermediate zone, the discs covering at least 20% of the cross-sectional area of the intermediate zone for use in a slurry bubble column reactor. Downcomer. The method according to any of the preceding claims, A downcomer for use in a slurry bubble column reactor, when the slurry bubble column reactor is in use, the middle zone comprises means for collecting gas bubbles in the slurry. The method of claim 14, A downcomer for use in a slurry bubble column reactor, wherein the means for gathering gas bubbles comprises a tube with an extended edge at the lower end. The method of claim 15, Downcomer for use in a slurry bubble column reactor, characterized in that the tube extends to the top of the downcomer. A slurry bubble column reactor comprising a downcomer according to any one of the preceding claims fixed in a reactor. The method of claim 17, Slurry bubble column reactor, characterized in that the vertical length of the downcomer is in the range of 30-120% of the intended depth of the slurry in the reactor when in use. The method of claim 17 or 18, A slurry bubble column reactor, comprising a gas phase above the slurry, the gas outlet from the upper portion being in communication with the gas phase. The method according to any one of claims 17 to 19, Slurry bubble column reactor, characterized in that the downcomer extends from the top region of the slurry to the bottom region of the reactor. The method according to any one of claims 17 to 20, A slurry bubble column reactor comprising a plurality of downcomers. The process of using the slurry bubble column reactor according to any one of claims 17 to 21 for carrying out a Fischer-Tropsch synthesis reaction. Performing a Fischer-Tropsch synthesis reaction comprising supplying hydrogen gas and carbon monoxide gas to a slurry comprising a Fischer-Tropsch catalyst in the reactor of any one of claims 17 to 21. How to.

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