Reactor for heterogeneous exothermic synthesis

 

(57) Abstract:

The invention relates to processes and apparatuses of chemical technology and can be used to implement the exothermic heterogeneous synthesis, in particular in the production of methanol or ammonia from synthesis gas. Describes a reactor that includes a vertical housing, the cover and bottom, fitting for input gas mixture and the output of the target product, gas-permeable horizontal partitions, which are the catalyst layers, at least one mixing chamber for mixing hot gas stream exiting the catalyst layer, and a cold gas stream supplied through the distribution means from the connection to the input gas mixture, below and parallel to the gas-permeable partition installed a blank wall, between which is formed an intermediate space which receives hot and cold gas streams, and the mixing chamber communicates with the intermediate space and is equipped with a flue, which is mounted so that through him out, additional mixing, the gas flow from the mixing chamber into the volume of the reactor below the intermediate space. The camera is ichno mixed in the intermediate space of the gas stream, made in its wall at the level of the intermediate space. It is located coaxially along the axis of the reactor sealed and connected with the gas-permeable wall and partially immersed in the catalyst bed. The flue gas in the mixing chamber is made in the shape of a tube mounted coaxially along the axis of the reactor. The technical result is the elimination of stress and deactivation of the catalyst. 1 C.p. f-crystals, 2 Il.

The invention relates to processes and apparatuses of chemical technology and can be used to implement the exothermic heterogeneous synthesis, in particular in the production of methanol or ammonia from synthesis gas.

It is known that to achieve the optimal values of the conversion process exothermic heterogeneous synthesis reaction occurs, passing the reaction mixture through several consecutive layers of catalyst, whereby the hot gas flow coming from each layer of the catalyst, should be chilled before serving in the subsequent layer to prevent overheating and deactivation of the catalyst layer. For this purpose, the reactor exothermic synthesis supply means, mixing the cold reaction mixture with hot gas leaving the layer.

Here the expression "hot gas" means a gas or mixture of partially reacted gases exiting the catalyst in the synthesis reactor, in which there is an exothermic reaction. For example, when an exothermic catalytic synthesis of methanol such hot gas has a temperature of from 240 to 290oC. the Expression "cold gas" means a gas with a temperature lower than the temperature of the hot gas emerging from the catalyst layer. Typically this gas consists of a gaseous reactant in predetermined proportions and has in the case of methanol synthesis temperature from 60 to 200oC.

Known for the design of the reactor, allowing for heterogeneous exothermic synthesis in consecutive adiabatic layers of the catalyst entering in the interlayer space of cold reactive gas for temperature regulation process. The reactor consists of a vertical cylindrical casing, a spherical cap and the bottom of the socket for input gas mixture and the output of the target product, distributors cold gas horizontally at different levels in the reactor and separating the solid layer of the catalyst on the conditional consecutive layers (Basal section in the shape of a diamond and placed around the distribution of cold gas. The walls of the chambers are made permeable to gas and impermeable to catalyst particles. The experience of operating reactors of this design showed that they provide low quality mixing, which leads to performance degradation of the reactor due to the occurrence in the catalyst temperature inhomogeneities.

Known for the design of the reactor, which allows to increase the degree of mixing of hot and cold gas by placing each layer of catalyst on a separate gas-permeable grate, education space between the layers and enter the cold gas in this space through special distributors (Japan's Bid N 58-52692, class C 07 C 31/04). However, the degree of mixing of hot and cold streams in these reactors also unsatisfactory.

Better mixing of the flows reach the reactor, providing for the mixing of streams in the mixing chamber (U.S. Patent N 3787189, class C 07 C 31/04).

However, the presence of the mixing chamber (U.S. patent N 3787189, class C 07 C 31/04) does not allow to set the Central column required for reactors with a diameter of more than 3 m, without the risk of degrading the quality of mixing, since the main contribution to the mixing by the x offset is carried out in a curved channel, placed between layers of catalyst that provides excellent mixing threads, but requires a large enough height for mounting of the mixer, thereby reducing the degree of use of the reactor volume, which is important for the economic characteristics of the synthesis reactors working, usually under high pressure.

The closest number of similar features to the claimed is a reactor for heterogeneous exothermic synthesis (U.S. patent N 3480407, class C 07 C 31/04) having a vertical cylindrical housing, the cover and bottom, fitting for input gas mixture and the output of the target product, as well as horizontal gas-permeable walls, which are the catalyst layers. Between the gas-permeable walls with layers of catalyst has a mixing chamber formed by two horizontal blank walls placed with a gap relative to each other. Mix hot and cold gas streams enter the mixing chamber through a window made in the side wall of the chamber, which connects the horizontal septum. Hot flow is formed in the catalyst bed, and the cold stream is directed from the nozzles enter the new flow chamber provided with vertically spaced blades, creating in her peripheral turbulent flows. The exit of the mixing chamber made in the form of holes in the lower horizontal partition in the Central part of the reactor. This reactor is taken as a prototype of the invention.

The shortcoming of this reactor is that it is not possible to eliminate the temperature inhomogeneity in the gas stream entering the next layer of the catalyst after the mixing chamber. The reactor is provided by mixing hot and cold gas streams, however, in cases where the hot gas stream has a temperature anisotropy generated in the previous layer of the catalyst, they are not eliminated in the mixing chamber, remain in the mixed gas stream and passed thus in the subsequent catalyst bed.

The invention is aimed at achieving homogeneous mixing of hot and cold gas streams, which allows you to virtually eliminate the occurrence of temperature inhomogeneities in the gas stream entering the catalyst layers, and as a result, overheating in the reactor catalyst and stable operation.

This result is achieved by a reactor for carrying out Ekster the new mix and output of the target product, horizontal gas-permeable partition that hosts the catalyst layers, at least one mixing chamber, in which there is a mixing of the hot gas stream exiting the catalyst layer, and a cold gas stream flowing through a distribution means from the connection to the input gas mixture, a blank wall, below and parallel to the aforementioned gas-permeable partition between which is formed under the layer of catalyst intermediate space which receives hot and cold gas flows and the mixing chamber associated with the intermediate space and is equipped with a flue, which is thus what it comes pre-mixed in the intermediate space and the mixing chamber, the gas stream passes through it, additionally mixed, and goes homogeneous mixed in the volume of the reactor below the intermediate space. The mixing chamber may be of any shape suitable for the implementation of the pre-mixing of gas streams, but preferably execute it in the form of a cylinder with a sealed lid and bottom and holes in the intermediate space in the side stance connected with the gas-permeable wall and partially immersed in the catalyst bed. The most appropriate to achieve complete mixing of the gas stream is the location of the duct coaxial with the axis of the reactor over the entire height of the mixing chamber, with a minimum clearance with respect to its cover, to ensure the delivery of a gas stream.

In Fig. 1 shows a sectional multilayer reactor for heterogeneous exothermic synthesis. In Fig. 2 in an enlarged scale shows a fragment of the reactor comprising the catalyst layer, the intermediate space, the mixing chamber and flue.

The reactor heterogeneous exothermic synthesis consists of a vertical cylindrical casing 1, a cover 2 and a bottom 3, the socket for input gas mixture 4 and output of the target product 5, a horizontal gas-permeable walls 7, which are the catalyst layers 8, the horizontal solid partition 9 placed with a gap under the gas-permeable walls, which together form the intermediate space 10, which receives hot gas flow through the gas-permeable wall of the catalyst layer, fittings 11 and nozzle 12 and distributors of cold gas 13 through which the intermediate space 10 comes Jolo is cnym space 10, duct 16 having an inlet 17 in the upper part of the mixing chamber 14 above the gas-permeable partition 7 and the outlet 18 located below the hollow partitions 9. The mixing chamber is closed at the top and bottom sealed by the walls 19 and 20. At the output 18 of the pipe 16 is installed distribution means 21 for uniform distribution of the mixed flow at the entrance to the next catalyst bed.

The reactor operates in the following way. The flow of the source gas mixture enters the reactor through the inlet fitting 4 is a first layer of catalyst 8, the gas-permeable wall 7 and enters the intermediate space 10, changes the direction of movement under the influence of hollow partitions 9 and is mixed with the cold gas flowing through the nozzle 11, pipe 12 and valve 13. Then partially mixed in the intermediate space, the flow of hot and cold gas from the intermediate space 10 through the openings 15 is fed into the mixing chamber 14. Passing through the annular space between the wall of the mixing chamber 14 and the duct 16, and then through the flue 16, the gas flow is completely homogeneous mix. Then the gas flow through the exit 18 of the duct 16 extends into the volume of the reactor, passes distribution Soroko and subsequent layers of catalyst are completely identical to those described. After passing the last in the reactor catalyst layer stream of the target product through an outlet fitting 5 is outside of the reactor.

Example. In the methanol synthesis reactor, the design of which corresponds to that shown in Fig. 1, with the diameter of 4.38 m and a height of 9.0 m on four gas-permeable walls posted a total of 140 tons of catalyst. At the entrance to the first layer serves synthesis gas in the amount of 340 thousand m3/h, heated to 220oC . Between the first and second layers is injected through the valve 170 thousand m3/h cold synthesis gas, between the second and third layers - 195 thousand m3/h, between the third and fourth - 150 thousand m3/h with a temperature of 50oC. survey Results of temperature distribution at the outlet of the catalyst after five months of operation recorded a slight temperature nonuniformity present in the catalyst. The maximum temperature difference in each layer was not more than 5oC. Provided almost complete mixing of the hot gas emerging from the catalyst layer, and add to it cold gas. The temperature distribution of the gas stream at the entrance to the next layer of the catalyst uniformly - maximum of resonator in this example, allowed to increase by 3-4% yield of methanol while reducing energy consumption for transportation of gas flow through the reactor by reducing the degree of recycling by increasing the conversion in a single pass gas through the catalyst layers.

1. Reactor for heterogeneous exothermic synthesis, comprising a vertical casing, the cover and bottom, fitting for input gas mixture and the output of the target product, gas-permeable horizontal partitions, which are the catalyst layers, and at least one mixing chamber for mixing hot gas stream exiting the catalyst layer, and a cold gas stream flowing through a distribution means, coupled with fitting for input gas mixture, and the mixing chamber has a capability message from the intermediate space formed between the gas permeable partition and the corresponding blank wall mounted below and parallel to the gas-permeable walls, characterized in that it is provided with a duct mounted coaxially to the mixing chamber and the axis of the reactor and is made in the form of a pipe connected to the volume of the reactor below the hollow partitions, while the mixing chamber is hermetically connected with a gas-permeable wall and partially immersed in the catalyst bed.

2. The reactor under item 1, characterized in that the mixing chamber is made in the form of a hollow cylinder with blind lid and techno mixed in the intermediate space of the gas stream.

 

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