RU2366499C2 - Reactor for implementation of heterogeneous catalytical reactions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: one or more catalyst baskets with perforated gas inlet and gas outlet walls are arranged in-line along the gas pass. The additional collectors perforated lengthwise are installed in the basket/baskets along the perimetre of gas outlet wall.

EFFECT: enhancing of the reliability and efficiency of reactor operation.

6 cl, 4 dwg

Description

The invention relates to reactors for conducting heterogeneous catalytic reactions, for example, for the synthesis of ammonia, the conversion of carbon monoxide with water vapor, and can be used in the chemical and petrochemical industries.

Known radial catalytic reactor containing a housing with fittings for input and output of reagents. Inside the housing, the inner and outer perforated cylinders are coaxially located, between which a layer of granular catalyst is placed (Nitrogen Guide. M: Chemistry 1986, 2nd edition, pp. 156-157).

The described reactor is used for conducting exothermic chemical reactions at medium pressure, for example, the conversion of carbon monoxide with water vapor.

Reactors for conducting exothermic pressure reactions, for example, ammonia synthesis, are also known. In the casing of each reactor, annular catalyst baskets with perforated walls located opposite each other are placed, in which each catalyst layer is equipped with means for providing a radial and axial-radial gas flow through them (Patent RU 2154524, B01J 8/04, 08.20.2000, , patent RU 2262381, B01J 8/04, 10.20.2005).

Closest to the proposed invention is a reactor for conducting heterogeneous catalytic reactions, comprising a housing, inside of which there are three catalyst baskets with perforated gas supply and gas outlet side walls and a catalyst inside. The reactor has bypass devices for controlling the temperature between the catalyst baskets, inlet and outlet manifolds, internal heat exchangers and a central pipe (US Patent 5171543, CL 422/148, B01J 8/04, 12/15/1992).

The disadvantages of these reactors is that to create a uniform flow of reagents through the catalyst bed, the perforation of the walls of the catalyst baskets is performed with an extremely small free section. The walls of the baskets form narrow gaps with gas-tight walls of the inner case, ending in a dead end at the bottom. These gaps serve as collectors for the supply of reagents to the catalyst layers and the withdrawal of reaction products from them.

The operating experience of reactors for the synthesis of ammonia of such a design showed that in a stationary mode the velocity of gas outflow through the perforation of the gas supply shell of the catalyst basket reaches 30–40 m / s. Under starting conditions, the gas outflow velocity can exceed 50 m / s. Under such conditions, the destruction of the catalyst particles adjacent to the perforation occurs. The consequence of this is the formation of catalyst dust and its ingress into the gas stream with an increase in the erosive effect of the stream on the grid and the catalyst. The crushed dust migrates through the granular catalyst layer and is carried out through the output collector of the previous layer to the input collectors of the subsequent layers. There is a gradual accumulation of catalyst dust in the catalyst layers and reservoirs and, accordingly, an increase in hydraulic resistance. In addition, the accumulation of catalyst dust in the collectors violates the uniformity of the flow of reagents in the catalyst bed, which leads to a decrease in the degree of conversion. All together, it forces a shutdown of production to repair the internal devices of the reactor, remove catalyst dust and replace the catalyst, which reduces the reliability and efficiency of the reactor.

The technical result to which the invention is directed is to increase the reliability and efficiency of the reactor.

The technical result is achieved in that in a reactor for carrying out heterogeneous catalytic reactions, comprising a housing, inside of which one or more catalyst baskets are arranged in series along the gas, with perforated gas supply and gas outlet side walls and a catalyst inside, collectors for supplying and removing gas, according to the invention inside the catalyst basket or catalyst baskets, additional collectors with gas permeation are installed around the perimeter at the gas supply wall mymi the entire length of the walls. Additional collectors are made mainly in the form of pipes, installed at a distance from the gas supply wall of the catalyst basket, providing free filling of the gap formed by the catalyst. The gas-permeable walls of the additional collectors are closed on all sides by a grid in one or more layers, with mesh sizes not exceeding 0.8 of the grain diameter of the catalyst. In addition, devices for collecting catalyst dust and catalyst particles, made as a part of a torus repeating the profile of the bottom of the catalyst basket, are located at the lower end of each additional collector.

The main distinguishing features of the proposed reactor are that inside the catalyst basket or catalyst baskets around the perimeter of the gas supply wall, additional collectors are perforated along the entire length.

Additional distinctive features is that the additional collectors are made predominantly in the form of pipes, installed at a distance from the gas supply wall of the catalyst basket, providing free filling of the resulting gap with the catalyst. The perforated walls of the additional collectors are also covered on all sides by a grid of one or several layers with mesh sizes not exceeding 0.8 of the grain diameter of the catalyst, and devices for collecting catalyst dust and catalyst particles placed in the form of a torus are placed at the lower ends of each additional collector repeating the profile of the bottom of the catalyst basket.

The present invention meets the condition of patentability "novelty", since the prior art failed to find a technical solution, the essential features of which would completely coincide with all the features available in the independent claim.

The present invention meets the condition of patentability "inventive step", since the prior art could not find a technical solution, the essential features of which ensured the fulfillment of the same technical task to which this invention is directed.

The proposed reactor is depicted in:

figure 1 - General view of the reactor, a longitudinal section,

figure 2 - additional collector,

figure 3 - the first catalyst basket, a longitudinal section,

figure 4 is a section aa of figure 3.

The reactor contains: a high pressure vessel 1, an inner vessel 2, a mixing chamber for the flows of the reaction mixture 3, located in the superlayer space of the first catalyst basket 4, the second and third catalyst baskets 5 and 6, supply 7, 8, 9 and discharge 10, 11, 12 collectors on each catalyst basket.

Inside the basket, the catalyst 13, 14, 15 are filled. The catalyst baskets have perforated gas inlets 16, 17, 18 located opposite each other and gas outlet walls 19, 20, 21 and impermeable elliptical bottoms 22, 23 and 24, additional perforated collectors 25, 26 and 27 located around the perimeter at the gas supply walls 16, 17, 18 of the catalyst baskets 4, 5, 6. All additional perforated collectors 25, 26 and 27 are covered with a protective mesh 28 in one or more layers with mesh sizes of no more than 0.8 of the grain diameter catalyst and have on the lower ends of the catalyst dust collecting device 29, made in the form of a part of a torus repeating the profile of the bottoms 22, 23, 24 of the catalyst baskets 4, 5, 6. To regulate the temperature, bypass devices 30, 31 and 32 are installed between the catalyst baskets 4, 5 and 6 A heat exchanger 33 is placed in the upper part of the reactor vessel. A heat exchanger 34 is installed between the exhaust gas perforated walls 19 and 20 of the catalyst baskets 4 and 5. The central pipe 35 is connected to the tube space of the heat exchanger 33 to discharge the reacted gas mixture from the reactor.

The reactor operates as follows.

The cold reaction mixture before entering the reactor is divided into main and bypass flows. The main stream of the mixture enters the lower part of the reactor and passes from bottom to top along the gap between the high pressure vessel 1 and the inner vessel 2 of the reactor, then through the annular space of the upper heat exchanger 33 and enters the mixing chamber 3. The second stream through the bypass 31 passes through the intermediate pipes heat exchanger 34 and enters the same mixing chamber 3. The third stream of cold reaction mixture bypass 32 is injected directly into the mixing chamber 3.

The total flow after mixing chamber 3 at the temperature of the beginning of the reaction enters the catalyst layer of the first basket 4 in three ways:

- on the catalyst layer 13 in the axial direction,

- along the supply manifold 7 through the gas supply wall 16 of the catalyst basket 4 in the radial direction,

- on additional collectors 25 through their perforation in the radial direction.

The reacted mixture from the catalyst layer of the first basket 4 enters through the exhaust gas perforated wall 19 into the exhaust manifold 10, mixes with cold gas (bypass 30) and enters the catalyst layer of the second catalyst basket 5 in a similar way:

- on the catalyst layer 14 in the axial direction,

- on the inlet manifold 8 through the gas supply wall 17 of the catalyst basket 5 in the radial direction,

- on additional collectors 26 through their perforation in the radial direction.

After the second catalyst basket 5, gas enters through the exhaust gas perforated wall 20 into the exhaust manifold 11, then into the annular space of the heat exchanger 34, is cooled by cold gas in the tube space and enters the catalyst layer of the third catalyst basket 6 in a similar way:

- on the catalyst layer 15 in the axial direction,

- along the supply manifold 9 through the gas supply wall 18 of the catalyst basket 6 in the radial direction

- on additional collectors 27 through their perforation in the radial direction.

The reacted reaction mixture through the gas exhaust perforated wall 21 enters the exhaust manifold 12 of the third catalyst basket 6. Next, the gas stream passes into the central pipe 35 and enters the tubes of the heat exchange device 33, transfers its heat to the cold gas and exits the reactor.

Thus, the gas flow enters the catalyst layer in three ways: through the side perforated wall of the catalyst basket, through additional collectors with perforated walls along the entire length, installed around the perimeter at the gas supply wall of the catalyst basket, and in the longitudinal direction through the gate catalyst layer.

This makes it possible to approach the most uniform distribution of the gas flow over the entire catalyst layer and to evenly use the entire loaded catalyst, thereby achieving the highest product yield under the selected operating conditions. Similarly, the accumulation of dust in the collectors and the catalyst bed is prevented, which allows us to assert the immutability of the hydraulic resistance of radial-axial triple-flow reactors over the lifetime.

By installing additional collectors in the catalyst basket or in the catalyst baskets, the following is achieved:

1. Uniform distribution of the gas flow over the catalyst layer and, as a result, in each catalyst basket a uniform profile of concentrations and temperatures along the axial coordinate in any radial position.

2. Low hydraulic resistance of the synthesis reactor, depending mainly on the distribution of perforation of the exhaust gas perforated walls of the catalyst baskets (adjustable parameter).

3. Low gas velocity at the outlet of the holes of the gas supply perforated walls of the catalyst baskets, which eliminates the destruction of the catalyst network and the adjacent catalyst layer and, as a result, the appearance of catalyst dust and its entry into the gas supply manifold.

4. The exception of the accumulation of catalyst dust due to special devices in the gas supply manifolds - dust collectors, which bring it to the bottom of the catalyst baskets.

5. Almost the same hydraulic resistance of the reactor throughout the life of the catalyst due to the absence of catalyst dust.

6. A flexible temperature control system in the catalyst layer, ensured by equal accessibility of all catalyst layers for cold bypasses.

Thus, the reliability and efficiency of the reactor are increased.

Claims (6)

1. A reactor for conducting heterogeneous catalytic reactions, comprising a housing, inside of which one or more catalyst baskets are installed in series along the gas, with perforated gas supply and gas outlet side walls and a catalyst inside, manifolds for supplying and discharging gas, characterized in that inside the catalyst basket or catalyst baskets around the perimeter at the gas supply wall, additional collectors perforated along the entire length are installed. 2. The reactor according to claim 1, characterized in that the additional collectors are made mainly in the form of pipes. 3. The reactor according to claim 1, characterized in that the additional collectors are installed at a distance from the gas supply wall of the catalyst basket, providing free filling of the resulting gap with the catalyst. 4. The reactor according to claim 1, characterized in that the perforated walls of the additional collectors are closed on all sides by a grid in one or more layers, with mesh sizes of not more than 0.8 of the grain diameter of the catalyst. 5. The reactor according to claim 1, characterized in that at the lower end of each additional collector placed a device for collecting catalyst dust and catalyst particles. 6. The reactor according to claim 5, characterized in that the devices are made as part of a torus repeating the profile of the bottom of the catalyst basket.

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