EA036977B1 - Tubular reactor - Google Patents

Abstract

The invention relates to chemical reactor designs, in particular, to structural execution of horizontal plug-flow reactors, and can be used for isomerization of vinyl norbornene (VNB) to ethylidene norbornene (ENB). The invention objective is simplification of the reactor design making it possible to maintain the turbulence mode and to provide an efficient contact of a reaction mix with a catalyst in order to carry out isomerization of VNB into ENB. Said objective is achieved by the proposed design of a tubular reactor, which comprises a horizontally placed tube with a heat-exchange system, pipes for feeding raw materials and catalyst components to the reaction space, and for discharging reaction products; the tube houses a turbolizer which is a rod located along the reactor axis, where half-ring partitions are rigidly secured, the outer radius of the partitions forms a 0.0001-0.0015 m gap with the inner tube surface, the partitions being located along the entire reactor length checker-wise at equal distances from each other. As can be seen, the proposed reactor design has a range of advantages: it has a low metal consumption, is easy to execute, allows for carrying out isomerization of VNB to ENB with a high yield of the target fraction.

Description

The invention relates to the design of chemical reactors, in particular to the design of horizontal plug-flow reactors, and can be used for isomerization of vinyl norbornene (VNB) to ethylidene norbornene (ENB).

In plug-flow reactors (PIV), the reaction mass moves in one direction without longitudinal or transverse movement. In view of the similarity of the movement of the reaction mass with the movement of the piston, this mode is also called piston. RIV are usually tubular devices or columns, the length or height of which significantly exceeds the diameter. The reactor can be horizontal, vertical or inclined, coil-shaped, and the like.

In the known method for producing ENB, it is indicated that the process of isomerization of VNB is carried out in a tubular reactor [1]. A structural description of the reactor is not provided.

Known invention, which describes the production of ENB in three stages, indicating the stage of isomerization of VNB in the third reactor [2]. The design of the reactor is not described.

Known tubular reactor [3], designed to carry out cationic oligomerization of olefins, which is made in the form of a pipe with a diameter of 0.05-0.15 m and a length of 1-10 m with a cooling jacket, branch pipes for one-sided input of raw materials (located at the pipe inlet at an angle of 90 ° to its axis) and catalyst (located at the pipe inlet along its axis) and a branch pipe for product output (located at the pipe outlet).

The disadvantages of this type of reactor are mainly unsuccessful design solutions: the location of the branch pipes for introducing the catalyst leads to unsatisfactory mixing of the reactants and the catalyst; effective and fast mixing of the reaction mass is not provided; a sharp increase in the temperature gradient between the inlet of the reactants and the outlet of the products from the reactor when the reactor is scaled up.

Closest to the present invention is a tubular reactor designed to carry out cationic oligomerization of olefins [4] (prototype). The reactor is made in the form of an inner tube with a total height of 1 to 5 m with an external cooling tubular jacket and is equipped with nozzles for introducing raw materials and catalyst components into the reaction space, nozzles for introducing and removing refrigerants and a nozzle for withdrawing products. Additionally, it is equipped with a reaction mass turbulator, which is a set of five to seven shaped or perforated plates rigidly connected to the outer surface of the pipe with the smallest diameter or to pipes with an odd number with an interval of 0.1-0.5 m, placed in the tubular reaction space, as well as sensors for temperature, pressure and flow rate of reagents at the inlet and outlet, a device for sampling, as well as additionally from 3 to 10 pipes of various diameters, coaxially located in the inner pipe and forming, together with it, a tubular-slot reaction space from 0.002 to 0.02 m.

The disadvantages of this reactor are the presence of additional parts that complicate its design and operation, and reduce the useful reaction space.

The objective of the invention is to simplify the design of the reactor, allowing you to maintain the turbulence mode and effective contact of the reaction mixture and the catalyst for the process of isomerization of VNB in ENB.

The task is achieved by the proposed design of a tubular reactor, which is a horizontally located pipe with a heat exchange system, nozzles for introducing raw materials and catalyst components into the reaction space and withdrawing reaction products, inside which a turbulator is located, which is a rod located along the axis of the reactor, on which it is rigid fixed partitions made in the form of half-rings, the outer radius of which forms a gap of 0.0001-0.0015 m with the inner surface of the pipe, while the partitions are staggered along the entire length of the reactor at an equal distance from each other.

The novelty of the invention is a constructive solution of a tubular reactor, not described in the patent literature, made in the form of a horizontally located pipe, and the turbulator is a partition made in the form of half rings, the outer radius of which forms a gap of 0.0001-0.0015 m with the inner surface of the body, while the half rings rigidly connected with a rod located along the axis of the reactor, and installed along its entire length in a checkerboard pattern at an equal distance from each other.

The efficiency of this design is ensured by the separation of the reaction mixture passing at a high volumetric velocity through the slit space formed by the turbulator and the reactor vessel, dividing into 2 streams: the main (jet) and additional (film), further mixing of which provides molecular and film mixing of the components, which increases the selectivity for the target product. The staggered arrangement of the turbulators ensures flow turbulence.

FIG. 1 shows a longitudinal section of the design of the proposed reactor, FIG. 2 shows a section of an element - a turbulator.

The tubular reactor includes a housing 1, a rod 2 with partitions 3 rigidly fixed on it in a staggered manner, pipes 4, 5 for introducing raw materials and catalyst and a pipe 6 for removing reaction products from the reaction space, a heat exchange system 7.

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The results obtained in the course of preliminary experiments showed that the optimal dimensions of a horizontal tubular reactor for the process of VNB isomerization in ENB are as follows: the length of the tubular reactor is 8 m, the inner diameter of the tubular reactor is 0.3 m, the length of the rod is 7.998, the diameter of the rod is 0.005, the distance between the half rings the turbulator is 0.32 m, the outer radius of the half-rings forms a gap of 0.0005-0.0015 m with the inner surface of the reactor.

Below are specific examples of the method for isomerization of VNB in ENB in a reactor with the specified optimal dimensions while changing the dimensions of the slot formed by the baffles and the inner surface of the reactor.

Example 1. VNB and a 10% solution of potassium amide in ammonia are introduced into the reactor in two simultaneous flows through the branch pipes at a feed: catalyst ratio of 10: 1. The slotted gap between the inner surface of the reactor and the half rings is 0.0005 m. The temperature regime is selected so that the temperature of the reaction mixture is 30 ° C. The reaction mixture is fed with a space velocity of 10 l / h. The time for the reaction mixture to pass through the reactor space is 9 minutes. The resulting products are removed from the reactor after the residence time. The ENB content (target fraction) is 99.1% by volume.

Example 2. The process is carried out under the conditions of example 1 in a reactor in which the gap between the inner surface of the pipe and the half rings is 0.001 m. The ENB content (target fraction) is 99.6 vol.%.

Example 3. The process is carried out under the conditions of example 1 in a reactor in which the slot gap between the inner surface of the reactor and the half rings is 0.0015 m. The ENB content (target fraction) is 99.3 vol.%.

Example 4. The process is carried out under the conditions of example 1 in a reactor, into which the reaction mixture is fed at a space velocity of 9 l / h. The ENB content (target fraction) is 99.2% by volume.

Example 5. The process is carried out under the conditions of example 1 in a reactor into which the reaction mixture is fed at a volumetric flow rate of 11 l / h. The ENB content (target fraction) is 99.0 vol.%.

Thus, the proposed design of the reactor has a number of advantages: it has a low metal consumption, is simple in execution, and allows the process of isomerization of VNB into ENB with a high yield of the target fraction.

List of references

1. Auth. wit. USSR No. 5911447

2. RF patent No. 2495862

3. Auth. wit. USSR No. 778199 dated 02/07/1979

4.Russian patent 2201799

Claims (1)

A tubular reactor made in the form of a pipe with a heat exchange system, nozzles for introducing raw materials and catalyst into the reaction space and withdrawing reaction products, inside which a turbulizer is located, characterized in that the reactor is a horizontally located pipe, and the turbulizer is a rod located along the axis of the reactor, on which partitions are rigidly fixed, made in the form of half rings, the outer radius of which forms a gap with the inner surface of the vessel with a size of 0.0005-0.0015 m, located along the entire length of the reactor in a staggered manner at an equal distance from each other.