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INVENTION
Russian Federation Patent RU2136359

Reactor for carrying out heterogeneous exothermic synthesis

Reactor for carrying out heterogeneous exothermic synthesis

Name of the inventor: Maples OP .; Zolotarsky IA .; Daut VA .; Zuckerman MJ
The name of the patentee: Institute of Catalysis SB RAS im.G.K.Boreskova
Address for correspondence: 630090, pr.Lavrenteva 5, Institute of Catalysis, Head of the patent department T.D.Yudinoy
Starting date of the patent: 1997.07.14

The invention relates to processes and apparatuses of chemical technology and can be used for the exothermic heterogeneous synthesis, in particular in the production of methanol or ammonia synthesis gas. Describes a reactor which comprises a vertical body, lid and bottom, nozzle input feed gas mixture and desired product output, gas permeable horizontal partitions on which there are layers of catalyst, at least one mixing chamber for mixing the hot gas stream exiting from the catalyst bed, and cold gas stream supplied through the distribution means of fitting to enter the feed gas mixture, below and parallel to the gas permeable partition installed blind baffle, between which is formed an intermediate space, which receives the hot and cold gas flows, and the plenum communicates with the intermediate space and is provided with a flue which is mounted so that it goes through a further mixing up, the gas flow from the mixing chamber into the reactor space below the intermediate space. the mixing chamber is in the form of a hollow cylinder with a blind bottom and a cover and openings therein for receipt of a part of the mixed gas stream intermediate space, made in its wall at the level of the intermediate space. It is located coaxially along the axis of the reactor and hermetically connected to a gas-permeable partition and is partially immersed in the catalyst bed. Gas duct in the mixing chamber is in the form of a tube and is mounted coaxially with and along the reactor axis. The technical result - the elimination of overheating and deactivation of the catalyst.

DESCRIPTION OF THE INVENTION

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

It is known that in order to achieve optimal values ​​of conversion in the exothermic heterogeneous synthesis reaction is carried out by passing the reaction mixture through several in series of catalyst beds, wherein hot gas stream exiting each catalyst layer should be cooled before entering the next layer in order to avoid overheating and deactivation a catalyst layer. For the exothermic synthesis reactors of the supply means, mixing the reaction mixture cold with the hot gas exiting from the catalyst bed, thus providing the last direct cooling before entering the next layer.

Here, "hot gas" means a gas or a mixture of partially reacted gases coming out of the synthesis reactor catalyst layer in which an exothermic reaction occurs. For example, the exothermic methanol synthesis catalyst such hot gas has a temperature of 240 to 290 o C. The expression "cold gas" means a gas having a temperature below the temperature of the hot gas exiting from the catalyst bed. Typically, such gas comprises gaseous reactants in predetermined proportions and in the case of a methanol synthesis temperature of from 60 to 200 o C.

Known reactor design that enables the heterogeneous exothermic synthesis in successive adiabatic catalyst beds with the introduction into the interlayer space of the cold temperature of the reaction gas for the process control. The reactor consists of a vertical cylindrical body, and a bottom spherical cap, fittings for entering feed gas mixture and desired product withdrawal, the cold gas distributors arranged horizontally at various levels in the reactor and separating the solid catalyst layer of conventional successive layers (Japanese Application N 58- 47214, cl. C 07 C 31/04). The mixing of hot and cold gas takes place in hollow chambers having a vertical section in a diamond-shaped and arranged around the cold gas distributors. The walls of the chambers are made permeable to gas and impermeable to catalyst particles. Operating experience has shown reactor design such that they provide poor quality of mixing, which leads to lower productivity of the reactor due to the occurrence of the catalyst layer temperature inhomogeneities.

Known reactor design, allowing to increase the degree of mixing of hot and cold gas by placing each catalyst bed in a separate gas-permeable grid, space formation between the layers and the cold gas entering into this space through special valves (Japan application N 58-52692, cl. C 07 C 31/04). However, the degree of mixing of hot and cold flow in these reactors and unsatisfactory.

Better flow mixing reactors reach providing mixing of streams into the mixing chamber (US patent N 3787189, cl. C 07 C 31/04).

But in this case the presence of the mixing chamber (US patent N 3787189, cl. C 07 C 31/04) does not establish central column required for reactors with diameters greater than 3 m, without jeopardizing the quality of the mixing, because the main contribution to the mixing of streams makes the collision and turbulence of the jets in the center of the reactor.

Known and reactors, in which the displacement is carried out in a curvilinear channel, placed between the catalyst beds to provide a high mixing flow but requires in this case a sufficiently large height for the installation of the mixer, thereby reducing the degree of use-core volume, which is important for economic characteristics synthesis reactors, employed typically under high pressure.

The closest to the number of similar features to the claimed a reactor for heterogeneous exothermic synthesis (US patent N 3480407, cl. C 07 C 31/04), having a vertical cylindrical housing and a bottom cap, for fitting the input feed gas mixture and desired product O and horizontal gas permeable septum and on which there are catalyst layers. Between gas permeable partitions with the catalyst layers there is a mixing chamber, formed by two horizontal partitions deaf placed with a gap relative to each other. Miscible hot and cold gas flows come into the mixing chamber through a window formed in a side wall of the chamber, which connects the horizontal partitions. The hot stream in the catalyst bed is formed, and the cold stream coming from nozzles entering feed gas mixture through the distribution means. To provide additional mixing chamber is provided with gas flows vertically arranged blades, creating in her peripheral turbulence. Out of the mixing chamber is designed as a hole at the bottom of the horizontal partition in the center of the reactor. This reactor is taken as a prototype of the invention.

The disadvantage of this reactor design is that it does not allow to eliminate the temperature inhomogeneity in the gas stream entering the successive catalyst bed after mixing chamber. The reactor is provided by mixing the hot and cold gas streams, but when the hot gas stream are temperature inhomogeneities generated in the preceding catalyst zone, they are not eliminated in the mixing chamber remain in the mixed gas stream and transmitted thereby to the subsequent catalyst bed.

The invention aims to achieve a homogeneous mixing of hot and cold gas streams, which almost completely eliminates the occurrence of temperature inhomogeneities in the gas stream entering the catalyst bed, and as a result, overheating of the catalyst in the reactor and stable operation.

This result is achieved in that the reactor for carrying out exothermic heterogeneous synthesis comprises a vertical body, lid and bottom, nozzle input feed gas mixture and desired product output horizontal gas permeable septum, in which catalyst beds are placed in at least one mixing chamber, wherein the mixing of hot gas effluent from the catalyst bed, and a cold gas stream entering through the distributor means from the nozzle for input of the initial gas mixture, the dead partition positioned below and parallel to said gas-permeable partition, between which is formed beneath the intermediate space catalyst, which receives hot and cold gas flows and the mixing chamber is connected with the intermediate space and is provided with a gas duct which is mounted so that it enters the pre-mixed in the intermediate space and the mixing chamber the gas flow passes through it, further stirring and is homogeneously mixed within the scope reactor below the intermediate space. mixing chamber may have any shape suitable for premixing gas streams, but performance is preferably in its cylindrical shape and with a leakproof lid and bottom openings at the intermediate space in the side walls. For optimal use of reactor volume mixing chamber is located along the reactor axis is sealed with a gas-permeable partition and is 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 throughout the height of the mixing chamber, with minimal clearance relative to its cover, providing a flow of the gas stream to it.

Reactor for carrying out heterogeneous exothermic synthesis Reactor for carrying out heterogeneous exothermic synthesis

FIG. 1 is a sectional view of a multilayer reactor for heterogeneous exothermic synthesis. FIG. 2 shows an enlarged fragment of the reactor, including the catalyst layer, the intermediate space, a mixing chamber and a flue.

Reactor for the heterogeneous exothermic synthesis consists of a vertical cylindrical body 1, lid 2 and bottom 3, fittings for input of the initial gaseous mixture 4 and the output of the target product 5, horizontal gas permeable partitions 7 in which the catalyst layers 8 placed, horizontal deaf baffles 9 arranged with a gap a gas-permeable septa, which together form an intermediate space 10 that receives a hot gas stream through the gas permeable septum of the catalyst bed nozzles 11 and pipes 12 and valves of the cold gas 13, whereby the intermediate space 10 enters the cold gas stream, cylindrically shaped mixing chamber 14 communicating via holes 15 with the intermediate space 10, the flue 16 having an inlet 17 in the upper part of the mixing chamber 14 above the gas-permeable partition 7 and an outlet 18 disposed below the partition hollow mixing chamber 9 is closed above and below the sealed partitions 19 and 20. The output 18 of the nozzle 16 is dispensing means 21 for uniform distribution of the mixed stream at the inlet of the following catalytic bed.

The reactor is operated as follows. Stream feed gas mixture enters the reactor through the inlet nozzle 4 passes first catalyst layer 8, a gas permeable partition wall 7 and enters the intermediate space 10 changes the direction of movement under the influence of hollow partitions 9 and mixes with the cold gas entering through fitting 11, tube 12 and valve 13. The partially mixed in the intermediate space hot and cold gas flow from the intermediate space 10 through the openings 15 enters the mixing chamber 14. Passing through the annular space between the wall of the mixing chamber 14 and flue 16 and then through a flue 16, the gas flow is completely homogeneously mixed. Then the gas flow 18 through the outlet gas duct 16 goes into the reactor, passes the distributor means 21 and then fed to the next catalyst bed. Sequence gas stream passing the second and subsequent catalyst beds is fully identical to that described. After passing through the last reactor in the catalyst layer of the target product flow through the outlet nozzle 5 goes beyond the reactor.

Example. The methanol synthesis reactor, whose design corresponds to that shown in FIG. 1, a body diameter of 4.38 m and 9.0 m high gas permeable partitions on four 140 m taken total catalyst. The input layer of the first syngas is fed in an amount of 340 thousand. M 3 / h, heated to 220 o C. Between the first and second layers are introduced through the distributor 170 thousand m 3 / h of cold synthesis gas between the second and third layers -. 195 thousand m 3 / h, between the third and fourth - 150 thousand m 3 / h with a temperature of 50 o C. results of examination of the temperature distribution at the outlet of the catalyst layers after five months of fixed small temperature inhomogeneities that exist in the catalyst layers. The maximum temperature difference in each layer was not more than 5 o C. ensured almost complete mixing of the hot gas coming from the catalyst layer, and add to it the cold gas. The temperature distribution of the gas stream entering the successive catalyst bed uniformly - maximum temperature difference does not exceed o 1,0.

Elimination of temperature inhomogeneities in the catalyst layers in this example has increased the yield by 3-4% methanol while reducing the energy consumption for transportation of gas flow through the reactor by lowering the degree of conversion by increasing the recycle in a single pass of gas through the catalyst layers.

CLAIM

1. Reactor for exothermic heterogeneous synthesis comprising a vertical housing and a bottom cap, for fitting the input feed gas mixture and desired product output horizontal gas permeable septum, which catalyst layers are disposed, and at least one mixing chamber for mixing the hot gas stream exiting from the catalyst bed, and a cold gas stream entering through the distributor means connected with the nozzle for input of the initial gas mixture, wherein the mixing chamber is made to communicate with the intermediate space formed between the permeable wall and the respective hollow baffle mounted below and parallel to the gas-permeable partitions, characterized in that it is provided with a flue mounted coaxially with the mixing chamber and reactor axis and is made in the form of a tube having access to the hollow volume of the reactor below the partition, while the mixing chamber is sealed with a gas-permeable partition and is partially immersed in the catalyst bed.

2. The reactor of claim. 1, characterized in that the mixing chamber is configured as a hollow cylinder with a blind bottom and a lid, and at the intermediate space in the chamber wall provided with holes for receipt partially mixed in the intermediate space the gas stream.

print version
Publication date 09.04.2007gg