RU2243028C1 - Reactor for a catalytic dehydrogenation of hydrocarbons - Google Patents

Abstract

FIELD: petrochemical industry; production of vinyl-aromatic hydrocarbons.

SUBSTANCE: the invention presents a reactor for a catalytic dehydrogenating of hydrocarbons. The reactor is dealt with the field of petrochemical industry and may be used for production of vinyl-aromatic hydrocarbons. The reactor has a cylindrical body and a coaxially installed basket with a catalytic agent. The basket consists of the external and internal perforated shells made out of profiled metal elements. The external and-or internal shell has a form of a polyhedron composed of the joint among themselves flat lattices of equal width consisting of the longitudinal located coaxially to the body of the reactor profiled elements and the transversal fastening rods. An area of a cross-section of a profiled element makes no more than 1.2 of an area of cross-section of a the rod, and the distance between the rods - no less than five diameters of a particle of the catalytic agent and width of the lattices is determined from the following dependence:

,provided that bL · Rrc and bL · 0.5 HL where: bL - width of a lattice of a corresponding shell, mm; dcp - a diameter of a catalyst particle, mm; Rrc - a radius of a circumference, on which vertexes of a polyhedron of a corresponding shell rest, mm; HL - height of a lattice of a corresponding shell, mm; k - a factor, which value is in the field of 0.5-15. The given design of the reactor ensures a raise of efficiency of its operation.

EFFECT: the invention ensures a raise of efficiency of the reactor operation.

16 cl, 25 dwg

Description

The invention relates to a device for the catalytic dehydrogenation of hydrocarbons and can be used in the petrochemical industry, for example, in the production of vinyl aromatic hydrocarbons, such as styrene, alpha-methyl styrene, vinyl toluene, divinylbenzod, as well as isoprene, butadiene, etc.

Known axial type reactor for the production of styrene, which is a cylindrical body with a fixed catalyst bed (NN Lebedev. Chemistry and technology of basic organic and petrochemical synthesis. Chemistry, 1975, p. 575).

A disadvantage of the known reactor is the large height of the catalyst layer and, accordingly, a large pressure drop across the layer, which reduces the dehydrogenation rate. Axial reactors are also characterized by difficulties in creating large unit capacities.

Closest to the proposed reactor and devoid of these drawbacks is a reactor for carrying out catalytic processes of a radial type, comprising a cylindrical body and a coaxially mounted basket with a catalyst, consisting of external and internal perforated shells of a cylindrical shape made of profiled metal elements and fastening rings (Pat. RF No. 2116825. Bull. No. 22, 08/10/98).

However, for this reactor, in relation to its use for the catalytic dehydrogenation of hydrocarbons, the following are characteristic:

- the complexity of the manufacture of fastening rings, as well as the assembly, disassembly and repair inside the reactor of perforated shells made of many profiled elements;

- insufficiently efficient distribution of gas flows over the catalyst bed;

- a narrow range of load changes for raw materials;

- high metal and energy intensity, if necessary, to assemble the reactor system of two or three reactors with adiabatic thermal conditions and intermediate heating of the reaction mixture in special heat exchangers installed between the reactors;

- a large temperature drop across the catalyst bed, as well as a large pressure drop across the reactor system, consisting of a number of sequentially arranged apparatuses, which reduces the efficiency of dehydrogenation processes;

- the location of the profiled elements having a hemisphere, semi-ellipse, triangle or truncated triangle cross-sectional view at the inlet of gas flows into the catalyst layer with a flat base towards the catalyst layer, which leads to erosion and destruction of the catalyst particles under the influence of gas jets.

The objective of the invention is to increase the efficiency of the reactor, reducing the complexity of manufacturing, assembling, disassembling and repairing perforated shells and reducing the metal consumption of the reactor.

A reactor for catalytic dehydrogenation of hydrocarbons is proposed, comprising a cylindrical body and a coaxially mounted basket with a catalyst, consisting of external and internal perforated shells made of profiled metal elements, in which the external and / or internal shell has the shape of a polyhedron composed of interconnected planar lattices of the same width, consisting of longitudinal profiled elements located transverse to the reactor vessel and transverse fastening rods. The cross-sectional area of the profiled element is not more than 1.2 of the cross-sectional area of the rod, and the distance between the rods is not less than five diameters of the catalyst particles, and the width of the gratings is determined by the dependence

provided that

b _p ≤ R _o and b _p ≤ 0.5 N _p ,

where b _p is the width of the lattice of the corresponding shell, mm;

d _to - the diameter of the catalyst particles, mm;

R _about is the radius of the circle on which the vertices of the polyhedron of the corresponding shell lie, mm;

N _p - the height of the lattice of the corresponding shell, mm;

k is a coefficient whose value lies in the range of 0.5-15.

The catalyst basket of the reactor can be divided into cells by flat or spiral-shaped continuous and / or perforated baffles attached to shells at the vertices of the polyhedra.

Between the outer and inner shells, one or more additional perforated shells may be installed.

Solid partitions can be made hollow, while the internal cavity of the partitions can have an oval, ellipse, semi-oval, semi-ellipse, rectangle, triangle, truncated triangle or spiral cross section and communicated with pipes for supplying and discharging the coolant.

Hollow partitions having a cross section of a triangle, a truncated triangle or spiral can be installed in such a way that their larger base is located on the outer shell.

The side walls of the partitions can have corrugations of a straight or zigzag shape, located transversely or at an angle to the direction of flow of the reaction mixture.

The partitions can be made of pipes located coaxially with the reactor vessel and connected to the nozzles for supplying and discharging the coolant.

Additional shells can be made of pipes located at a distance from each other coaxially to the reactor vessel and connected to pipes for supplying and discharging the coolant.

Profiled elements having a cross section of a semicircle, semi-ellipse, triangle, or truncated triangle can be arranged with a flat base facing the flow of the reaction mixture, while the distance between the profiled elements is not more than 0.9 of the diameter of the catalyst particles, and the width of the perforated element is not more than 1 8 times the length of the catalyst particle.

The essence of the device is illustrated by drawings, where in Fig.1 shows a reactor according to the first embodiment; figure 2 - reactor according to the second embodiment; figure 3-10 shows sections in the horizontal plane of the various options for the catalyst baskets installed in the reactor; 11-16 illustrate options for assembling gratings from various profiled elements and fastening rods (in FIGS. 11, 12, 13 — cuts of gratings in the vertical plane and, respectively, FIGS. 14, 15, 16 — cuts of gratings in the horizontal plane); on Fig 17 shows a variant of the Assembly of the shell (section of the shell in the horizontal plane); in Fig.18 shows sections in the horizontal plane of various options for hollow partitions, in Fig.19-21 shows side views of partitions having corrugations of various shapes, and Fig.22-25 - cross sections of these partitions.

The reactors shown in figures 1 and 2 consist of a cylindrical body 1, inside of which there are external 2 and internal 3 perforated shells, between which there is a catalyst layer 4. The body has nozzles for entering the steam-raw material mixture 5, leaving the reaction mixture 6, supplying coolant 7 and heat transfer fluid 8. In the catalyst layer coaxially with the reactor vessel, heat transfer pipes 9 are connected to the nozzles for supply and removal of heat transfer fluid. The heat exchange pipes in the reactor of Fig. 1 are tubular elements of two pipes — a pipe in a pipe in which the inner pipe 10 is connected to a pipe for supplying a heat transfer medium, and the annular space of the heat exchange pipe 9 is connected to a pipe for transferring a heat transfer medium.

In the reactor of FIG. 2, a cylindrical baffle 11 divides the heat exchange tubes into a two-way system in which the outer row of tubes is connected to a nozzle for supplying a coolant, and the inner row of tubes is connected to a nozzle for withdrawing a coolant.

The reactor of FIGS. 1 and 2 has a distribution manifold 12 and a collecting manifold 13, as well as a collecting chamber 14, 16 and a distributing chamber 15.

Figure 3 presents cross sections of the catalyst basket for various reactor designs.

In FIGS. 3-5 and 7, the inner and outer shells have the shape of a polyhedron; 6 and 8, the outer shells are in the form of a polyhedron, and the inner shells are in the form of cylinders; 9 and 10, the inner shells have the shape of a polyhedron, and the outer shells have the shape of a cylinder,

Figure 3 shows a variant of the catalyst basket, the perforated shells of which 2 and 3 are assembled from flat lattices of width b _p consisting of profiled elements of width b _e having a cross-section in the shape of a triangle, the flat base of which is directed towards the flow of the reaction mixture entering the catalyst layer from central distribution manifold 12.

Figure 4 shows a variant of the catalyst basket, divided into cells by flat 17 and perforated 18 partitions attached to the shells at the vertices of the polyhedra, as well as an additional perforated shell 19.

Figure 5 presents an option for using flat hollow partitions having the shape of a rectangle 20 in cross section, and figure 6 is a variant of the hollow partitions in the form of a spiral 21.

Fig.7 shows the division of the catalyst basket with an additional shell 22 of pipes, for example, for the reactor version of Fig.1, and Fig.8 is a basket with two shells 23 and 24 of pipes, for example, for the reactor version of Fig.2.

Figure 9 shows the division of the catalyst basket into cells and sections with flat partitions 25 and an additional shell 26 made of pipes.

Figure 10 shows the division of the basket into cells with spiral walls 27 of pipes.

For the variants of FIGS. 6 and 10, various types of spirals can be used, such as Archimedean, hyperbolic, logarithmic, and others. Preferred is a reamer (involute) of the circumference of the inner perforated shell of the catalyst basket. In this case, the cells in which the catalyst is located are spiral channels, the cross section of which in the direction of the reaction mixture can be, for example, the same or increasing, taking into account the increase in the volume of the reaction mixture during the dehydrogenation process and maintaining the linear velocity of the gas flow along the channel constant.

Figures 11-16 show some of the possible options for assembling flat gratings of width b _p , consisting of longitudinal profiled elements 28 of width b _e with a distance between them a and transverse fastening rods 29 with a distance between them b _c . On Fig shows a variant of the Assembly of the shell of the lattice width b _p .

The cross section of the hollow partitions can be in the form of an oval, ellipse, semi-oval, half-ellipse, rectangle, triangle, spiral, etc. Some of them are shown in Fig. 18. The side walls of the partitions have corrugations of a straight or zigzag shape, which can be obtained, for example, by stamping methods (see Fig.19-21). Possible corrugation profiles (cross-section of partitions) are shown in Fig.22-25.

Gaseous or liquid high-temperature coolants can be used as the heat transfer medium, with the use of superheated water vapor being preferred.

Gaseous feedstock (steam-feed mixture) enters the reactor through the pipe 5 and then through the distributing manifold 12 and the inner perforated shell 3 are uniformly distributed in the horizontal direction throughout the volume of the catalyst layer 4.

The reaction mixture (contact gas) leaves the catalyst layer through the outer perforated shell 2 and leaves the reactor through the collecting manifold 13 and nozzle 6.

In a possible embodiment of the process in the reactor of FIG. 1, superheated water vapor is supplied through the nozzle 7 and the inner pipes 10 to the heat exchange tubes 9, forming an annular, permeable contact gas additional partition 22 (see FIG. 7), which divides the catalyst layer into two steps. Having passed through heat exchange pipes, where superheated water vapor transfers heat passing through the catalyst layer of the reaction mixture, water vapor passes through the collection chamber 14 and pipe 8 to leave the reactor. Thus, in this reactor, a two-stage dehydrogenation of hydrocarbons is carried out with intermediate heating of the reaction mixture with superheated steam through the blank wall of the heat exchange tubes.

When carrying out the process in the reactor of Fig. 2 and, respectively, in Fig. 8, superheated water vapor is supplied through the pipe 7 and the distributing chamber 15 to the heat transfer pipes of the external additional partition 23 and then passing the heat exchange pipes of the internal additional partition 24 through the collecting chamber 16 and the pipe 8 leaves the reactor. In this reactor, three-stage contacting of the feedstock with the catalyst is carried out during the intermediate heating of the reaction mixture between the steps. In this case, the most effective countercurrent regime of the coolant and the reaction mixture is carried out.

The use of assembled, including by machine, flat lattices outside the reactor of longitudinal profiled elements and transverse fastening rods significantly reduces the complexity of manufacturing, assembling, disassembling, and reconditioning perforated shells in the form of polyhedra in comparison with the prototype.

With the same width of flat lattices (the width of the faces of the polyhedron), the symmetry of the structure is achieved, which is necessary for uniform distribution of the reaction mixture over the catalyst layer.

The location of the profiled elements in the lattice coaxially with the reactor vessel (vertically) helps to maintain the uniformity of the catalyst layer during its shrinkage during catalyst loading and reactor operation.

The claimed ratio of the cross-sectional areas of the profiled element and the fastening rod, as well as the distance between the rods corresponds to the achievement of the necessary strength of the shell while ensuring its allowable hydraulic resistance.

The proposed dependence for determining the width of lattices (faces of a polyhedron) is a modified formula for calculating the length of the chord of the circumference of the corresponding shell at the height of the segment cut off by the chord equal to the particle diameter of the catalyst used, taking into account the indicated limitations.

The thickness of the catalyst layer at the vertices of the polyhedron exceeds the minimum thickness by (h _o2 -h _o1 ) - see figure 3. The possible non-uniformity of the flow of gas flows is eliminated by installing partitions in the catalyst basket attached to the shell at the vertices of the polyhedra, taking into account the increased permeability of the catalyst layer along the surface of the partitions.

The installation between the outer and inner shells of additional perforated shells dividing the volume of the catalyst basket into sections improves the distribution of gas flows over the entire volume of the catalyst due to the effect of sectioning and redistribution of the gas stream on the additional perforated shells. At the same time, sections along the reaction mixture can be loaded with a catalyst with different activity, particle size distribution, fresh, spent catalyst, inert packing, and also at the exit from the catalyst basket to remain empty, which increases the manufacturability of the reactor in existing plants, and also allows, if necessary carry out processes at a reduced load on raw materials.

The implementation of the endothermic processes of catalytic dehydrogenation of hydrocarbons in reactors with the placement of heat-conducting elements inside the catalyst layer — hollow partitions, including pipes, (FIGS. 5-10) allows us to approach more efficient conditions with an isothermal and even increasing profile of temperature changes in the catalyst layer along the reaction mixture in comparison with the prototype having a decreasing temperature profile.

The location of the hollow partitions having a cross section of a triangle, a truncated triangle or spiral with a large base on the outer shell allows increasing the linear velocity of the gas flow along the catalyst bed, especially in the second half of the layer, and improving the gas distribution over the layer.

The corrugated side walls of the hollow partitions increase the strength of the partitions and improve heat transfer between the coolant and the reaction mixture, and the arrangement of the corrugations vertically or at an angle to the vertical promotes free shrinkage of the catalyst when it is loaded into the reactor and during its operation.

The location of the profiled elements with a flat base facing the flow of the reaction mixture under these conditions extinguishes the gas jets in the expanding section of the channel between the elements and reduces erosion and destruction of the catalyst particles at the gas inlet to the layer.

The multi-stage contacting of the raw materials in the proposed reactor with intermediate between the stages of heating the reaction mixture with superheated steam through the blank wall of the heat exchange tubes significantly reduces the temperature drop on the catalyst layers during the implementation of endothermic hydrocarbon dehydrogenation processes, which allows to increase the average integral temperature over the catalyst layer, which leads to a decrease in water vapor consumption aimed at diluting the feedstock, increasing the conversion and selectivity of percent ssov dehydrogenation, and also reduces the metal content of the reactor compared to the prototype system.

Claims (16)

1. A reactor for catalytic dehydrogenation of hydrocarbons, comprising a cylindrical body and a coaxially mounted basket with a catalyst, consisting of external and internal perforated shells made of profiled metal elements, characterized in that the outer and / or inner shell has the shape of a polyhedron composed of interconnected flat lattices of the same width, consisting of longitudinal profiled elements arranged coaxially with the reactor vessel and transverse fastening rods, while the cross-sectional area of the profiled element is not more than 1.2 of the cross-sectional area of the rod, and the distance between the rods is not less than five diameters of the catalyst particles and the width of the gratings is determined by the dependence:

provided that b _p ≤ R _o and b _p ≤ 0.5 N _p , where b _p is the width of the lattice of the corresponding shell, mm; d _to - the diameter of the catalyst particles, mm; R _about is the radius of the circle on which the vertices of the polyhedron of the corresponding shell lie, mm; N _p - the height of the lattice of the corresponding shell, mm; k is a coefficient whose value lies in the range of 0.5-15. 2. The reactor according to claim 1, characterized in that the shaped elements having a cross section of a semicircle, half-ellipse, triangle or truncated triangle are arranged with a flat base facing the flow of the reaction mixture, while the distance between the shaped elements is not more than 0.9 of the diameter of the catalyst particles, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 3. The reactor according to claim 1, characterized in that the catalyst basket is divided into cells by flat or spiral-shaped solid and / or perforated baffles attached to shells at the vertices of the polyhedra. 4. The reactor according to claim 3, characterized in that the shaped elements having a semicircle, semi-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the shaped elements is not more than 0.9 of the diameter of the catalyst particle, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 5. The reactor according to claim 1 or 3, characterized in that between the outer and inner shells one or more additional perforated shells are installed. 6. The reactor according to claim 5, characterized in that the shaped elements having a semicircle, half-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the shaped elements is not more than 0.9 of the diameter of the catalyst particle, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 7. The reactor according to claim 3, characterized in that the solid partitions are hollow, while the internal cavity of the partitions in cross section has the shape of an oval, ellipse, semi-oval, semi-ellipse, rectangle, triangle, truncated triangle or spiral and communicated with nozzles for supplying and heat transfer fluid. 8. The reactor according to claim 7, characterized in that the shaped elements having a semicircle, half-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the shaped elements is not more than 0.9 of the diameter of the catalyst particle, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 9. The reactor according to claim 7, characterized in that the hollow partitions having a cross section of a triangle, a truncated triangle or spiral are installed in such a way that their larger base is located on the outer shell. 10. The reactor according to claim 9, characterized in that the profiled elements having a semicircle, semi-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the profiled elements is not more than 0.9 of the diameter of the catalyst particle, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 11. The reactor according to claim 7 or 9, characterized in that the side walls of the partitions have corrugations of a straight or zigzag shape located transversely or at an angle to the direction of flow of the reaction mixture. 12. The reactor according to claim 11, characterized in that the profiled elements having a semicircle, semi-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the profiled elements is not more than 0.9 of the diameter of the catalyst particles, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 13. The reactor according to claim 3, characterized in that the partitions are made of pipes arranged coaxially with the reactor vessel and connected to the nozzles for supplying and discharging the coolant. 14. The reactor according to item 13, wherein the profiled elements having a semicircle, semi-ellipse, triangle or truncated triangle section are arranged with a flat base facing the flow of the reaction mixture, while the distance between the profiled elements is not more than 0.9 of the diameter of the catalyst particles, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles. 15. The reactor according to claim 5, characterized in that the additional shells are made of pipes located at a distance from each other coaxially to the reactor vessel and connected to pipes for supplying and discharging the coolant. 16. The reactor according to p. 15, characterized in that the shaped elements having a cross section of a semicircle, half-ellipse, triangle or a truncated triangle are arranged with a flat base facing the flow of the reaction mixture, while the distance between the shaped elements is not more than 0.9 of the diameter of the catalyst particles, and the width of the profiled element is not more than 1.8 times the length of the catalyst particles.

Images