DESCRIPTION

BUBBLE COLUMN TYPE HYDROCARBON SYNTHESIS REACTOR

TECHNICAL FIELD

The present invention relates to a bubble column type hydrocarbon synthesis reactor, and in particular to a reactor that carries out a Fischer-Tropsch synthesis reaction by introducing a synthesis gas into a slurry having solid catalyst particles suspended in a liquid hydrocarbon.

The present application claims priority to Japanese Patent Application No. 2006-20659 filed on January 30, 2006, the entire contents of which are incorporated herein for reference.

BACKGROUND ART

As one of the reaction systems for a Fischer-Tropsch synthesis reaction (hereinafter called FT reaction) that generates a hydrocarbon compound and water by a catalytic reaction from a synthesis gas which is mainly composed of hydrogen and carbon monoxide, a bubble column type slurry phase FT reaction system that carries out a FT reaction by introducing a synthesis gas into a slurry in which solid catalyst particles are suspended in a liquid hydrocarbon is available. Further, a hydrocarbon compound synthesized by the FT reaction is mainly utilized as a raw material for fuel oil and lubricant oil.

In an FT reactor used for the bubble column type slurry phase FT reaction system, it is necessary to equally scatter catalyst particles in a liquid hydrocarbon in the reactor in order to keep the reaction temperature uniform inside the reactor.

However, since it is usual that the specific gravity of the catalyst particles is heavier than that of a liquid hydrocarbon, there is a tendency for the catalyst particles to be unevenly distributed and accumulated in the vicinity of the bottom of the reactor.

A technology has been proposed as solving means of such a problem, which improves a dispersed state of catalyst particles by providing another gas introducing portion separately from the main introducing port on the upper part of the main introducing port (distributor) of a synthesis gas (For example, refer to US Patent No. 5,252,613).

However, in the case of the system as described in the above-described patent document, since it is necessary to provide another gas introducing port separately from the main introducing port, there is a problem in that the internal structure of the reactor becomes complex, and the piping outside the reactor also becomes complex.

It is necessary to adjust or regulate the flow rate of gas supplied into the slurry between the main introducing port and another gas introducing port. Therefore, there is another problem in that a regulation mechanism (for example, regulator valve, etc.) is required.

The present invention was developed in view of such problems. It is therefore an object of the invention to evenly disperse catalyst particles in a liquid hydrocarbon in a reactor without providing another gas introducing port separately from the main introducing port of a synthesis gas in a bubble column type hydrocarbon synthesis reactor that carries out a Fischer-Tropsch synthesis reaction.

DISCLOSURE OF THE INVENTION

The inventor et al. found, based on earnest research and study to solve the above-described problems, that it is possible to disperse catalyst particles, which are

about to be accumulated on a screen, by means of an agitation effect of gas ejected from a introducing port by installing the screen, the mesh of which is smaller than the catalyst particles, directly below the introducing port (distributor) of a synthesis gas, and completed the invention based on the findings.

That is, a bubble column type hydrocarbon synthesis reactor according to the invention synthesizes a hydrocarbons by a chemical reaction of a gas whose main components are hydrogen and carbon monoxide, and a slurry having solid catalyst particles suspended in a liquid, and includes: a reactor main body for accommodating the slurry; a reaction gas-feeding portion that is disposed at the lower part of the reactor main body and feeds the gas into the slurry by ejecting the same; and a barrier member that is disposed forward of the ejecting direction of the gas ejected from the reaction gas-feeding portion and restricts the flow of the slurry.

In the bubble column type hydrocarbon synthesis reactor according to the invention, the barrier member may be installed in a range where the flow of the slurry, which is produced by the gas ejected from the reaction gas-feeding portion, is reached.

In the bubble column type hydrocarbon synthesis reactor according to the invention, the barrier member may be disposed equidistantly from all the gas ejecting ports for ejecting the gas downward of the gas ejecting ports of the reaction gas-feeding portion.

In the bubble column type hydrocarbon synthesis reactor according to the invention, the barrier member may include a filtering element that does not allow the catalyst particles in the slurry to pass therethrough.

In the bubble column type hydrocarbon synthesis reactor according to the invention, the filtering element may be installed in a part of the barrier member.

According to the bubble column type hydrocarbon synthesis reactor of the

invention, catalyst particles accumulated on the barrier member are agitated by an agitation effect of gas ejected from the distributor, and thus the dispersion effect into the slurry can be improved. As a result, the temperature inside the reactor can be maintained more uniformly, wherein the composition of the liquid hydrocarbon product can be stabilized.

Also, according to the bubble column type hydrocarbon synthesis reactor of the invention, since it is not necessary for another gas introducing port to be provided separately from the distributor, the structure inside the reactor and arrangement of the piping outside the reactor can be simplified. Further, it is not necessary to provide a mechanism for adjusting or regulating the flow rate of gas supplied into the slurry between the distributor and another gas introducing port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view showing the entire configuration of an FT reactor according to Embodiment 1 of the invention.

FIG. 2 is an enlarged longitudinal sectional view showing the major parts of the FT reactor according to Embodiment 1 of the invention, which is depicted in FIG. 1.

FIG. 3 is an enlarged longitudinal sectional view showing a synthesis gas feeding nozzle that composes the distributor depicted in FIG. 2.

FIG. 4 is a cross-sectional view showing the FT reactor depicted in FIG. 2, which is taken along the line III-III.

FIG. 5 is a top plan view showing a barrier member according to Embodiment 1 of the invention, which shows an example having a screen provided on the entire surface thereof.

FIG. 6 is a top plan view showing a barrier member according to Embodiment 1 of the invention, which shows an example having a screen provided on a part of the surface thereof.

FIG. 7 is a view showing a method for diffusing catalyst particles according to Embodiment 1 of the invention, which shows a state where the catalyst particles are accumulated on the screen.

FIG. 8 is a view showing a method for diffusing catalyst particles according to Embodiment 1 of the invention, which shows a state where the catalyst particles are agitated.

FIG. 9 is a view showing a state where catalyst particles are agitated by a distributor according to a modified version of Embodiment 1 of the invention.

BEST MODES FOR CARRYING OUT THE INVENTION A detailed description is given of a preferred embodiment of the invention with reference to the accompanying drawings. In the specification and the drawings, components that are substantially identical to each other in function and configuration are given the same reference numerals, and overlapping description thereof is omitted. (Embodiment 1)

First, based on FIG. 1, a description is given of a bubble column type slurry phase FT synthesis reactor (hereinafter merely called an FT reactor) 1 that is one example of a bubble column type hydrocarbon synthesis reactor according to Embodiment 1 of the invention.

As shown in FIG. 1, the FT reactor 1 according to the present embodiment is essentially provided with a reactor main body 10, a distributor 20, a barrier member 30 and a cooling tube 40.

The reactor main body 10 is a roughly cylindrical vessel made of metal, the diameter of which is 1 to 20 meters, preferably 2 to 10 meters, and the height of which is 10 to 50 meters, preferably 15 to 45 meters. Slurry 12 having solid catalyst particles 124 suspended in a liquid hydrocarbon (product of the FT reaction) 122 is contained in the interior of the reactor main body 10.

The distributor 20 is one example of a reaction gas-feeding portion according to the present embodiment. The distributor 20 is disposed at the lower part in the interior of the reaction main body 10, and ejects a synthesis gas, the main components of which are hydrogen and carbon monoxide, downward and feeds the same into the slurry 12. The distributor 20 is provided with a synthesis gas feeding pipe 22, a nozzle header 24 attached to the distal end part of the synthesis gas feeding pipe 22, and a plurality of synthesis gas feeding nozzles 26 attached to the side part of the nozzle header 24. The details thereof are described later.

The barrier member 30 is installed forward of the ejecting direction of the synthesis gas ejected from the distributor 20, that is, downward of the distributor 20, and restricts the flow of the slurry 12. Also, the barrier member 30 may include a filtering element that does not allow the catalyst particles 124 in the slurry 12 to pass therethrough. The liquid hydrocarbon 122 is separated from the catalyst particles 124 by the filtering element, and only the liquid hydrocarbon 122 can be discharged through the liquid hydrocarbon discharge port 14 secured at the bottom part of the reactor main body 10. On the other hand, when it is not necessary for the liquid hydrocarbon 122 to be discharged from the bottom part of the reactor main body 10, it may not be necessary for the filtering element to be provided in the barrier member 30. The details of the barrier member 30 will also be described later.

The cooling tube 40 is provided along the height direction of the reactor main

body 10 in the interior of the reactor main body 10 and cools the slurry 12, the temperature of which is raised due to heat generated by the FT synthesis reaction. The cooling tube 40 may be formed so as to reciprocate a plurality of times (for example, it reciprocates two times in FIG. 1) vertically in the perpendicular direction by bending a single tube as shown in, for example, FIG. 1. However, the shape and number of cooling tubes are not limited to the above-described shape and number, but may be such that the cooling tubes are evenly disposed in the interior of the reactor main body 10 and contribute to uniform cooling of the slurry 12. For example, a plurality of cooling tubes having a double-tube structure of a so-called bayonet type may be installed in the interior of the reactor main body 10.

Cooling water (for example, the temperature of which is different by -50 through 0 ⁰ C from the interior temperature of the reactor main body 10) introduced from the cooling tube inlet 42 is made to circulate in the cooling tube 40. By exchanging heat between the cooling water and the slurry 12 via the tubular wall of the cooling tube 40 in the process during which the cooling water circulates in the cooling tube 40, the slurry 12 in the interior of the reactor main body 10 is cooled down and reaction temperature is constant. Some of the cooling water is discharged from the cooling tube outlet 44 as steam. In addition, the medium for cooling the slurry 12 is not limited to cooling water as described above, but, for example, a straight chain, branched-chain and annular paraffin, olefin, low-molecular-weight silane, silyl ether, and silicone oil, etc., of C4 through ClO may be used as the medium.

Next, based on FIG. 1 through FIG. 4, a detailed description is given of the configuration and operations of the distributor 20 and the barrier member 30 according to the embodiment.

As described above, the distributor 20 is provided with the synthesis gas

feeding pipe 22, nozzle header 24 and a plurality of synthesis gas feeding nozzles 26.

The synthesis gas feeding pipe 22 passes through the side wall of the reactor main body 10 and is bent downward toward the perpendicular direction at the middle part of the interior of the reactor main body 10 and in the vicinity thereof. The nozzle header 24 is attached to the distal end part of the bent synthesis gas feeding pipe 22, and the nozzle header 24 is made to extend in the diametrical direction of the reactor main body 10. Also, a plurality of synthesis gas feeding nozzles 26 (nine nozzles at one side of the nozzle header 24 in the present embodiment) are provided in a direction roughly orthogonal to the nozzle header 24 at both sides in the lengthwise direction of the nozzle header 24. In the embodiment, the respective synthesis gas feeding nozzles 26 are made longer and longer as they approach the middle part of the nozzle header 24 in compliance with a circular sectional shape of the reactor main body 10, and are made shorter and shorter as they approach both the ends thereof, so that the synthesis gas is evenly distributed in the slurry 12 in the interior of the reactor main body 10. However, the shape and number of the nozzle header 24 and synthesis gas nozzles 26 are not specially restricted.

Furthermore, as shown in FIG. 3 and FIG. 4, a plurality of synthesis gas-ejecting ports 26a, 26b and 26c are formed along the lengthwise direction in the synthesis gas feeding nozzle 26 (in FIG. 4, the synthesis gas-ejecting ports 26a and 26c are not illustrated for convenience). It is preferable that the synthesis gas-ejecting ports 26a, 26b and 26c be installed in the lower half area of the synthesis gas feeding nozzle 26 so that the synthesis gas is ejected downward (in the direction toward the bottom part of the reactor main body 10). However, the synthesis gas-ejecting ports 26a, 26b and 26c are not necessarily formed in the lower half area of the synthesis gas feeding nozzle 26, wherein if such a structure is employed by which the synthesis gas

is ejected downward, these ports may be formed at any optional position. In addition, ports for ejecting the synthesis gas upward may be formed in the upper half area of the synthesis gas feeding nozzle 26 in addition to the ports for ejecting the synthesis gas downward.

Further, as shown in FIG. 3, the synthesis gas ejecting ports 26a, 26b and 26c according to the embodiment are formed so that the ejecting directions of the ejecting ports adjacent to each other are shifted by 45° in order that the synthesis gas can be evenly and efficiently ejected. However, the arrangement of the synthesis gas-ejecting ports 26a, 26b and 26c is not limited to the above-described arrangement, and the number of ejecting ports is not limited to three ports.

In the distributor 20 having such a structure as described above, the synthesis gas supplied from the exterior of the reactor main body 10 into the distributor 20 via the synthesis gas feeding pipe 22 passes through the interior of the nozzle header 24 and is ejected into the slurry 12 downward (that is, the direction shown by the arrow in the drawing) from the synthesis gas-ejecting ports 26a, 26b and 26c secured at the lower part (the bottom part side of the reactor main body 10) of the synthesis gas feeding nozzle 26. Thus, the synthesis gas introduced from the distributor 20 into the slurry 12 is made into bubbles 28 and drifts from bottom to the top toward the height direction (the perpendicular direction) of the reactor main body 10 in the slurry 12. In the process, the synthesis gas is dissolved in the liquid hydrocarbon 122 and is brought into contact with the catalyst particles 124, whereby a synthesis reaction of a liquid hydrocarbon (FT synthesis reaction) is carried out.

Still further, the synthesis gas is introduced from the distributor 20, which is disposed at the lower part of the interior of the reactor main body 10, into the slurry 12, and the synthesis gas thus introduced in is made into bubbles 28 and is passed upward

in the interior of the reactor main body 10, whereby, in the interior of the reactor main body 10, as shown by thick arrows in FIG. 1, an ascending flow of the slurry 12 is generated in the middle part of the reactor main body 10 and in the vicinity thereof (that is, in the vicinity of the center axis of the reactor main body 10), and a descending flow thereof is generated near the inner wall of the reactor main body 10 (that is, near the inner-circumferential portion).

As shown in FIG. 2, the barrier member 30 is composed of a screen 32 operating as one example of the filtering element according to the embodiment and a screen supporting member 34 for supporting the screen 32 from its downside, and the barrier member 30 is installed forward in the ejecting direction of the synthesis gas ejected from the distributor 20, that is, downward of the distributor 20.

The screen 32 may be, for example, a filter that includes a plurality of slits having a smaller slit width than the size of the catalyst particles 124, does not permit the catalyst particles 124 to pass through, and allows only the liquid hydrocarbon 122 and bubbles 28 to pass through. By installing such a screen 32 at the bottom part of the reactor main body 10, only the flow of the catalyst particles downward of the screen 32 is restricted.

The screen supporting member 34 is a member for supporting the screen 32 from its downside and is composed so as to permit at least the liquid hydrocarbon 122 and bubbles 28 to pass through so that it does not hinder the role of the screen 32 as a filter.

Herein, a detailed description is given of the configuration of the barrier member 30 according to the embodiment with reference to FIG. 5 and FIG. 6.

First, where the screen is provided on the entire surface of the barrier member 30, as shown in FIG. 5, the screen 32 including a plurality of slits 32a having a smaller

width d than the size of the catalyst particles 124 and wires 32b provided at both sides of the slit 32a is installed on the entire upper surface of the barrier member 30. It is preferable that the slit width d of the screen 32 be sufficiently smaller than the mean particle size of the catalyst particles 124 so that the catalyst particles 124 are not permitted to pass through downward of the screen 32. That is, it is preferable that the slid width d be, for example, 50% or less of the mean particle size of the catalyst particles, preferably 10 through 30% thereof.

Thus, since the screen 32 including a plurality of slits 32a having a sufficiently smaller slit width d than the mean particle size of the catalyst particles 124 is installed, the liquid hydrocarbon 122 and the catalyst particles 124 are separated from each other, and only the liquid hydrocarbon 122 can be discharged from the liquid hydrocarbon discharge port 14 installed at the bottom part of the reactor main body 10.

On the other hand, since the catalyst particles 124 are not permitted to pass through the screen 32, they will be accumulated on the screen 32. However, the catalyst particles 124 that will be accumulated on the screen 32 are raised upward of the reactor main body 10 by ejecting the synthesis gas from the above-described distributor 20 onto the screen 32. Further details are described later.

Next, where the screen 32 is installed on a part of the barrier member 30, as shown in FIG. 6, for example, the screen 32 installed at the opening 33 formed at the middle part of a shield plate 36 is supported from its downside by the screen supporting member 34. Therefore, a barrier member having the screen 32 operating as a filtering element installed at the middle part and having the shield plate 36 installed at the peripheral portion (that is, the inner wall side of the reactor main body 10) is provided in the interior of the reactor main body 10.

Such a shield plate 36 as described above prevents the synthesis gas ejected

from the distributor 20 from being permitted to pass through downward, differing from the screen 32 having the slits 32a formed therein. Therefore, the catalyst particles 124 can be more efficiently raised upward than by the screen 32, wherein it is possible to effectively disperse the catalyst particles 124 in the slurry 12 in the interior of the reactor main body 10. In addition, by installing the screen 32 at a part of the barrier member 30, the liquid-phase component (liquid hydrocarbon 122) in the interior of the reactor main body 10 can be discharged through the liquid hydrocarbon discharge port 14 at the bottom part of the reactor main body 10.

Furthermore, the range where the screen 32 is provided, that is, the size of the opening 33 of the shield plate 36 is not especially limited. However, it is preferable that the range be determined by taking into consideration the balance between the discharge efficiency of the liquid hydrocarbon 122 and dispersion effect of the catalyst particles 124. Further, a steel plate, aluminum plate, or any optional material may be used as the shield plate 36 as long as the material has such a shape as described above, sufficient mechanical strength and heat-resisting temperature.

The catalyst particles 124 are likely to be accumulated at the peripheral portions of the barrier member 30. Therefore, as in the embodiment, if the screen 32 operating as one example of the filtering element is disposed at the middle part of the reactor main body 10, and the shield plate 36 having an excellent dispersion effect for the catalyst particles 124 is disposed at the peripheral portions in the interior of the reactor main body 10, it is possible to further effectively disperse the catalyst particles 124 in the slurry 12.

Also, when it is not necessary for the liquid hydrocarbon 122 to be discharged from the bottom part of the reactor main body 10, a metal plate such a steel plate may be used as the barrier member 30 without providing any filtering element in the barrier

member 30. This case is not substantially different from a reactor of a flat bottom part being used.

Further, it is preferable that the barrier member 30 be installed in the range accessible by the flow of the slurry, which is produced by a synthesis gas ejected from the distributor 20. In detail, for example, the barrier member 30 may be installed so that the distance between the barrier member 30 and the distributor 20 becomes 30 cm or less, preferably 10 cm or so. Thus, if the barrier member 30 is installed at a distance sufficiently close to the distributor 20, the flow of the slurry 12, which is produced by the synthesis gas ejected from the distributor 20, reaches the catalyst particles which will be accumulated on the screen 32 of the barrier member 30, wherein the catalyst particles 124 can be sufficiently agitated, and the catalyst particles 124 can be effectively dispersed in the slurry 12.

Still further, the barrier member 30 is installed parallel to the distributor 20, that is, so as to become parallel to the horizontal plane perpendicular to the height direction of the reactor main body 10. Normally, with the structural strength as a pressure vessel of the reactor taken into consideration, the bottom part of the reactor main body 10 is formed so as to form a curvature as shown in FIG. 2. In such a case, it becomes difficult for the synthesis gas ejected from the distributor 20 to reach the middle part of the bottom part of the reactor main body 10, wherein the catalyst particles 124 are likely to be accumulated at the bottom part thereof. Accordingly, as in the embodiment, by horizontally installing the barrier member 30, it is possible to prevent the catalyst particles 124 from being accumulated.

Next, based on FIG. 7 through FIG. 9, a description is given of a method for dispersing the catalyst particles 124 according to the embodiment. In FIG. 7 through FIG. 9, the configuration of the FT reactor 1 is described, after being simplified for

convenience of description.

As shown in FIG. 7, where a nozzle for introducing gas from upward of a distributor 200' as in the prior art is provided, the catalyst particles 124 are accumulated on the barrier member 30 unless a gas introducing nozzle is separately provided and the gas is introduced from downward of the barrier meter 30. In particular, the catalyst particles 124 are likely to be accumulated at the peripheral portions of the inner wall side of the reactor main body 10.

Accordingly, in the embodiment, as shown in FIG. 8, the distributor 20 is installed at a distance sufficiently close to the barrier member 30, and gas is ejected downward from the distributor 20 toward the barrier member 30, whereby, as shown by the thick arrows in FIG. 8, the catalyst particles 124 that will be accumulated on the barrier member 30 are raised upward, and the catalyst particles 124 are evenly dispersed in the slurry 12 in the interior of the reactor main body 10.

In addition, as shown in FIG. 9, such a distributor 200 may be employed as a reaction gas-feeding portion for introducing a synthesis gas, which is provided with a two-stage gas introducing nozzle consisting of an upper-stage introducing nozzle 210 and a lower-stage introducing nozzle 220. In this case, the synthesis gas is ejected upward from the upper-stage introducing nozzle 210, and the synthesis gas is ejected from the lower-stage introducing nozzle 220 to at least the barrier member 30 downward. Further, synthesis gas may be ejected upward from the lower-stage introducing nozzle 220 in addition to downward ejecting of the synthesis gas.

Thus, by providing the gas introducing nozzle in two upper and lower stages, the catalyst particles 124 raised by the synthesis gas ejected from the lower-stage introducing nozzle 220 to the barrier member 30 can be raised further upward by an air-lift effect based on the synthesis gas ejected by the upper-stage introducing nozzle

210. Therefore, by employing the distributor 200 having two-stage gas introducing nozzles, the dispersion effect of catalyst particles 124 can be further improved compared to the case where a distributor 20 having a single-stage gas introducing nozzle as shown in FIG. 8 is employed, wherein the composition of the produced liquid hydrocarbon 122 can be further stabilized.

As described above, with the FT reactor 1 according to the embodiment, since gas ejected from the distributor 20 or the lower-stage introducing nozzle 220 of the distributor 200 is introduced onto the barrier member 30, the catalyst particles 124 that will be accumulated on the barrier member 30 are agitated, and dispersion of the catalyst particles 124 in the slurry 12 can be promoted. Therefore, the temperature of the interior of the reactor main body 10 can be maintained more uniform, wherein the composition of the liquid hydrocarbon, which is a product synthesized by the FT reaction, can be stabilized.

In addition, the barrier member 30 is horizontally provided in the reactor main body 10, and gas is ejected onto the barrier member 30 from the distributor 20 or the lower-stage introducing nozzle 220 of the distributor 200, whereby the dispersion effect of catalyst particles can be increased. That is, since it is not necessary to provide another gas introducing port separately from the distributor as in the prior art in order to increase the effect of dispersing the catalyst particles 124 in the slurry 12, it is possible to simplify the interior structure of the reactor main body 10 and the arrangement of pipes outside the reactor main body 10. Further, since the distributor 20 or the distributor 200 alone is sufficient as a member for introducing gas, it is not necessary to employ a mechanism for adjusting or regulating the flow rate of gas between a plurality of gas introducing nozzles as in the prior art.

A description was given above of a preferred embodiment of the invention

with reference to the accompanying drawings. It is a matter of course that the invention is not limited to the above-described embodiment, and it is obvious that various types of modifications and variations are conceivable by one skilled in the same art in the category described in the scope of claims of the invention. Therefore, it is understood that such various types of modifications and variations naturally belong to the technical scope of the invention.

For example, in the above-described embodiment, the shape of the reactor main body 10 is roughly cylindrical. However, the shape of the reactor main body is not specifically limited as long as the shape is able to upwardly raise catalyst particles which will be accumulated on the barrier member or on the bottom part of the reactor main body and to evenly disperse the catalyst particles in the slurry.

Also, in the above-described embodiment, the cooling tube 40 is formed so as to reciprocate a plurality of times vertically along the perpendicular direction by bending a single tube. However, as long as the type is evenly disposed in the reaction area in the interior of the reactor main body and can contribute to even cooling of the slurry, the shape and number of the cooling tubes are not specifically limited. For example, a plurality of a double-tube structure cooling tubes of a so-called "bayonet type" may be disposed in the interior of the reactor.

Additionally, a screen having a plurality of slits formed therein is used as a filtering element included in the barrier member. However, the filtering element may be, for example, a meshed filter having meshes whose apertures are sufficiently smaller than the size of the catalyst particles. Or, a porous sintered plate may be employed.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a bubble column type hydrocarbon synthesis reactor, and particularly to a reactor for carrying out a Fischer-Tropsch synthesis reaction by introducing a synthesis gas into a slurry having solid catalyst particles suspended in a liquid hydrocarbon.