RU2539984C1 - Reactor with stationary layer of catalyst - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: annular space by the partitions is sectioned into odd number of paths so that all paths, except for the last one, are located on periphery of pipe lattice, and the last - at the centre, and the diameter of this path by the size coincides with the diameter of the reactionary zone, and the pipe ends are arranged uniformly along the cross section of this zone.

EFFECT: reactor has improved overall performance and decreased metal consumption.

3 cl, 6 dwg

Description

The invention relates to chemical reactors with a stationary catalyst bed and can be used in processes with a large thermal effect.

Catalytic processes proceeding with a large adiabatic change in the temperature of the reaction mixture are carried out in shelf (sectioned) reactors made in the form of columns, inside which the catalyst is placed on the lattice shelves and means for cooling or heating the reaction mixture are placed between the catalyst layers.

A known reactor for conducting exothermic catalytic reactions, including a housing with hatches, bottoms with devices for introducing vapors of raw materials and product outlet, catalyst layers and means for removing heat of reaction, made in the form of distributing devices for supplying cooling gas and convective heat exchangers (RF Patent No. 2206384, B01J 8/04 of 02/21/2002). Each heat exchanger is located in the narrowing of the free section of the reactor formed by the surfaces of the shaped inserts in the reactor vessel. Each distribution device is located under the shaped insert in the expansion zone of the free section of the reactor.

The disadvantage of this reactor is its limited use exclusively for gas-phase reactions that occur at high speed and do not require high catalyst layers.

Closest to the proposed reactor is a partitioned type reactor, including heat exchangers for cooling the reaction stream between the catalyst beds (Petrochemistry Handbook, revised by Ogorodnikov SK, Chemistry, v.1, p.130, 1978). Changing the temperature of the reaction stream in such a reactor can be carried out by controlling the flow rate of the coolant through the heat exchanger or its temperature.

The disadvantages of this reactor are the large surface of the heat exchangers and the high inertia of the heat exchange method used. The number of sections in such a reactor (usually no more than 10) and the distribution of the catalyst between them are determined based on the values of the adiabatic temperature difference and the optimal degree of conversion in each layer. Cooling (heating) of the reaction mixture between the shelves is carried out by built-in or external heat exchangers. The reaction mixture is fed into the tube, and the coolant in the annulus.

Preference is given to built-in heat exchangers, which gives compactness and reduces metal consumption. However, the built-in heat exchanger in this type of reactor has low thermal efficiency, especially in reactions occurring in the liquid phase on a finely divided catalyst. This is due to the fact that in a dense layer of a finely dispersed catalyst, due to the high hydraulic resistance, the speed of the reaction mass is limited to no more than 0.1 m / s, and in most cases no more than 0.01 m / s. The same speed order is maintained in the tubes of the heat exchanger due to the need for uniform distribution of the flow of the reaction mixture over the cross section of the reactor.

The objective of the invention is to increase the efficiency of the built-in heat exchange device, which leads to a reduction in the number of sections and a decrease in the metal consumption of the reactor.

The technical result achieved is achieved by a reactor with a stationary catalyst bed consisting of a multi-section housing, a cover and a bottom, fittings for supplying and outputting reaction products, each section of which consists of a reaction zone — a cylindrical body with a device for holding a fine-grained catalyst, and a heat-exchange zone of a shell-and-tube heat exchanger, into the tubes of which the reaction mixture is supplied, and into the annular space - the coolant, while the tube space with the help of partitions is divided into echetnoe number of turns so that all passages except the last, are arranged around the periphery of the tube sheet, and the last - in the middle, the diameter of the turn size coincides with the diameter of the reaction zone, and the pipe ends are uniformly distributed over the cross section of the zone.

Additionally, the reactor is equipped with an inclined blank plate for receiving the reaction mixture in the next section.

In addition, the strokes of the upstream heat exchanger are provided with a drainage hole.

Dividing the pipe space into passages increases the heat transfer efficiency, an odd number of strokes allows you to organize the flow of products along the axis of the reactor without additional strapping, and a uniform arrangement of the ends of the pipes along the cross section of the reaction zone allows the effective distribution of the reaction mixture in the catalyst bed.

Figure 1, figure 2, figure 3 and figure 4 presents a diagram of the proposed reactor and heat exchange device to it.

The reactor (FIG. 1) is a section consisting of heat exchange zones 1 and reaction zones 2 located below them with holding grids 3. FIG. 1 shows two sections. The proposed design allows you to use the number of sections necessary for a particular process. To supply raw materials to the heat exchange zone, fitting 4 is mounted, and to reduce (or to increase) the temperature of the reaction mass, the annular space of the heat exchange zone is equipped with fittings for supplying and withdrawing heat carrier 5 and 6, respectively. To connect the reaction products from the bottom of the last reaction zone, a fitting 7 is mounted. The intermediate reaction zones have blind inclined plates 8 located below the holding grids with a drain into the heat exchange zone of the underlying section. The bias of the blank plate towards the discharge of the reaction mixture helps to remove catalyst dust, which can be carried away with the flow of the reaction mixture.

The solid catalyst is poured onto the holding device, which is used as a holding grid 3 and a mesh with a cell placed on it, the size of which is smaller than the grain size of the catalyst. A neutral nozzle can be placed on the mesh to hold catalyst dust. A neutral packing can also be stacked on top of the catalyst bed to improve the distribution of the reaction mixture in the upper catalyst bed.

Figure 2, 3, 4 presents a diagram of a heat exchange device.

The heat exchange device consists of an upper cover 9, an upper tube sheet 10, a lower tube sheet 11 and a lower cover 12, tubes 13 mounted in a tube sheet.

The inner surface of the upper cover 9 and the end section of the upper tube sheet 10 are divided by vertical partitions into an odd number of parts (in this case, the partitions A, B into three parts), limited by these partitions, and the end section of the lower tube sheet 11 and the inner surface of the lower cover 12 also divided vertically by an odd number of parts (in this case, partitions C, D into three parts), limited by these partitions.

Partition diagrams A, B, C, D are shown in FIGS. 5 and 6.

Depending on the breakdown of the tube sheet into a circle or a square, the configuration of the partitions changes accordingly.

This separation of the tube sheets allows any reasonable number of strokes in the tube space to be used, with the last stroke at the exit of the reaction mixture to the reaction zone occupying the entire section of the reactor, and the tubes are evenly distributed over this section. The arrangement of moves involves a commensurate number of pipes in each sector.

In this case, the sectors formed by the partitions A, B, C, D are five moves 14, 15, 16, 17, 18.

The internal passages 15 and 17, in which there is an upward flow, are provided with a drainage hole (not shown in the diagram), which also serves as the release of catalyst dust carried away by the flow of the reaction mixture.

The reactor with a stationary catalyst bed (figure 1) works as follows.

The initial products enter the tube space of the heat exchange zone 1 of the first section through the nozzle 4, where they acquire the temperature necessary for the catalytic process due to the coolant supplied to the annular space through the nozzle 5.

Heat transfer in the tube space occurs during the sequential passage of the starting products through the passages of the heat exchange zone 14, 15, 16, 17 and 18 (Figs. 2, 3, 4). A five-fold increase in the speed of flow allows a significant increase in the efficiency of heat transfer.

At the exit of the course 18, the flow is evenly distributed over the cross section of the reaction zone 2, which favorably affects the subsequent results when a chemical reaction proceeds on a solid catalyst.

Passing from top to bottom, the starting products undergo chemical transformation in a given proportion, and the reaction heat is released (absorbed), as a result of which the temperature of the reaction mixture acquires a limiting set temperature. The uniform distribution of the reaction mixture over the cross section of the reaction zone is extremely important, since the unevenness leads to the formation of stagnant zones (internal circulation), which is expressed in a local violation of the temperature regime and deterioration.

After passing through the catalyst bed, the reaction mixture enters an inclined blank plate into the next section in the heat exchange zone to obtain the required temperature.

Alternating processes of temperature control - chemical transformation take place in a given number of sections and after the completion of the chemical reaction, the reaction mixture through the nozzle 7 is displayed for processing.

Claims (3)

1. A reactor with a stationary catalyst bed, consisting of a multi-section vessel, a cover and a bottom, fittings for supplying and outputting reaction products, each section of which consists of a reaction zone — a cylindrical body with a device for holding a fine-grained catalyst, and a heat exchange zone — a shell-and-tube heat exchanger, in the tube of which the reaction mixture is supplied, and the coolant is introduced into the annulus, characterized in that the tubular space is divided into an odd number of strokes by means of partitions in such a way The reason is that all the passages except the last one are located on the periphery of the tube sheet, and the last one is centered, the diameter of this stroke being the same as the diameter of the reaction zone, and the pipe ends are evenly distributed over the section of this zone. 2. The reactor with a stationary catalyst bed according to claim 1, characterized in that for receiving the reaction mixture in the next section, it is equipped with an inclined blank plate. 3. The reactor with a stationary catalyst bed according to claim 2, characterized in that the passages of the upstream heat exchange device are provided with a drainage hole.

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