RU1780825C - Radial chemical reactor - Google Patents

Abstract

Field of use: chemical engineering, in particular radial type reactors with a catalyst bed. SUMMARY OF THE INVENTION: A reactor includes a catalyst bed, an external and an internal cylindrical grating, end walls, a housing, a distribution channel, a receiver, a displacement rod, a discharge channel, an output pipe, a supply pipe, a distribution manifold, hollow generators, a collecting manifold, and pipes for removing a cooling medium. The mixture of reagents from the receiver through the distribution channel enters the catalyst bed, from where the reaction products, cooled on the inner cylindrical grating, enter the outlet channel and are led out of the reactor through the outlet pipe. The cooling medium through the nozzles and the distribution manifold enters the hollow generators of the inner cylindrical grate and is discharged from the reactor through the collecting manifold and the discharge nozzles. 1 s P. f-ly, 3 ill. sl c

Description

The invention relates to chemical engineering, in particular to radial type reactors with a catalyst bed located between two cylindrical coaxial grids and blown reactants in the radial direction.

A radial type chemical reactor is known comprising two coaxial perforated cylinders, the annular space between which is filled with solid granular material, and a gas distribution device.

In this reactor, a minimum acceptable level of product yield is achieved by compensating for axial unevenness in gas distribution by installing a switchgear.

The disadvantages of the reactor are instability to thermal disturbances, design complexity, and low product yield.

A radial type chemical reactor is known including a cylindrical body, a coaxially mounted annular basket with a catalyst, inside which a central body of revolution is placed.

In this reactor, an increase in the yield is achieved by increasing the stability of the work by equalizing the differential pressure in the radial direction by positioning the central body of revolution.

The disadvantage of the reactor is its relatively low product yield, hydro and thermomechanical instability of operation.

The closest technical solution to the proposed one, accepted as a prototype, is a radial type chemical reactor containing a catalyst layer bounded by two coaxial cylindrical gratings, distribution and discharge channels.

In this reactor, an increase in operational stability is achieved by equalizing the differential pressure in the radial direction by profiling both the distribution and the discharge channels.

The disadvantage of such a reactor is the low yield of products due to the occurrence of thermomechanical instability, since equalization of the differential pressure in the radial direction only has an indirect effect on thermal stability.

The aim of the present invention is to increase the yield of products by reducing the likelihood of thermomechanical instability,

This goal is achieved in that the elements forming the inner cylindrical grid are hollow.

The implementation of the elements forming the inner cylindrical lattice, hollow is the main distinguishing feature of the claimed decision from the prototype and determines compliance with the criterion of novelty.

Comparison of the claimed solution not only with the prototype, but also with other technical solutions in the art allows us to conclude that they do not have features similar to the essential distinguishing features of the claimed reactor, and to recognize for the declared solution the essential criteria distinguish.

SUMMARY OF THE INVENTION

Consider the flow of reagents through the filling of the catalyst, provided that the reaction is exothermic. An insignificant local increase in temperature (caused, for example, by inhomogeneous filling) will lead to an increase in viscosity and a decrease in gas density. This will cause an increase in the local hydraulic resistance of the section and a decrease in the mass filtration rate through it, which contributes to a further increase in temperature and resistance, and so on. In the backfill, a section with an increased relatively optimal (calculated) temperature appears. Due to the constant consumption of reagents around the overheated area

there is an increase in the filtration rate relative to the calculated one and, associated with this, a local decrease in temperature below the optimum. Indignation grows

while processes of the opposite nature (thermal conductivity, convective and radiant transfer) stabilize the situation. It should be emphasized that it is similar to thermo; - mechanical instability is essentially

manifests itself only in radial-type apparatuses: in which the presence of a grained layer sandwiched between two gratings and radial gas pumping is combined. The tightness of the layer sharply weakens convective processes, and the uniformity of the radial distribution strongly depends on the hydraulic characteristics of the granular layer. In apparatuses of other types — a fluidized bed, axial with a free granular backfill (with one grating), hot spots are usually destroyed by convection even before their significant manifestation.

The reaction at non-calculated temperature leads to a decrease in yield

received products. Quantitatively, the effect of thermomechanical instability is determined by the excess of the temperature in the hot region over the average in the apparatus. This excess is determined in

ultimately the temperature difference between the inlet and outlet of the gas from the reactor. Therefore, cooling the reaction products at the outlet will reduce the likelihood of thermomechanical instability and, therefore, increase the yield of the resulting product.

The reaction products are cooled by interacting with an internal cylindrical lattice made in

in the form of hollow elements installed along generators and connected by means of collectors with nozzles for supplying and removing refrigerant. If you use straight pipes with a single

the passage of the refrigerant, then in the lower part of the reactor, cooling will be more efficient than in the upper because of the greater temperature difference between the refrigerant and the reaction products. Therefore execution

hollow elements in the form of coils with several passages of the coolant can significantly increase the uniformity of cooling the grating and reduce the likelihood

occurrence of thermomechanical instability.

A schematic diagram of a radial type chemical reactor is shown in FIG. 1 (section along the longitudinal axis); in FIG. 2 - section of an internal cylindrical lattice; FIG. 3- hollow device

elements of the inner cylindrical lattice in the form of coils.

A radial type chemical reactor includes: a catalyst layer 1, an external 2 and an internal 3 cylindrical gratings, end walls 4, a housing 5, a distribution channel b, a receiver 7, a displacement rod 8, a discharge channel 9, an outlet pipe 10, an inlet pipe 11, distribution manifold of cooling gas 12, hollow forming elements 13 (in the form of coils), collecting manifold 14 and branch pipes of the cooling gas outlet 15.

The catalyst layer 1 is located between the outer 2 and inner 3 coaxial cylindrical gratings and the end walls 4 in the housing 5 so that between the inner surface of the housing 5 and the outer cylindrical grate 2 an annular distribution channel b is formed, connected to the receiver 7. The volume limited by the inner cylindrical grate 3 and the displacement rod 8 forms an annular outlet channel 9 connected to the outlet pipe 10. The cooling gas supply pipes 11 are connected through a distribution manifold 12 sec. bubbled generators 13 of the inner cylindrical screen 3. At the top of the hollow body 5 forming a collecting manifold 13 through 14 is connected to the discharge nozzles 15 of the cooling gas.

The reactor operates as follows. The mixture of reagents from the receiver 7 through the distribution channel 6 enters the catalyst bed 1, from where the mixture of reaction products cooled on the hollow elements 13 of the inner cylindrical grating 3 enters the outlet channel 9 and is discharged from the reactor through the pipe 10. The cooling gas enters through the nozzles 11 into the distribution manifold 12, is heated inside the hollow elements 13, is collected in the manifold 14 and exits the reactor through the nozzle 15.

In a radial type chemical reactor of the proposed design, experiments were carried out to obtain formaldehyde from methanol on a silver-containing catalyst. The diameter of the working zone of the reactor is 200 mm; the height is 100 and 200 mm. The cooling of the inner cylindrical lattice was carried out due to forced circulation of cooling water

inside hollow elements in the form of coils installed along generators.

The reaction mixture, containing 35% methanol, 14% oxygen and 51% inert 5 gzz, enters the catalyst bed, which is a T mm diameter bead sprayed with silver. A reaction takes place in the catalyst bed, which each results in a mixture containing formaldehyde,

0 hydrogen, unreacted methanol, oxygen, water, carbon dioxide and inert gases.

If there is no cooling of the internal cylindrical grate, the output

5 formaldehyde was 31%. With cooling, the yield of formaldehyde increased by 0.5% at a height of the working zone of the reactor of 100 mm and by 0.8-1% at a height of the working zone of 200 mm.

0 Thus, the use of the invention in comparison with the prototype will increase the yield by 0.5-1%.

Execution of elements forming

5, the internal cylindrical grating allows, in comparison with the prototype, to provide the following technician o-economic advantages: to increase the yield of products by 0.5-1%.

0 In addition, an additional positive effect will be:

-the possibility of hardening reaction products;

- reduction of hydraulic losses in the outlet channel 5 due to wall cooling;

-increasing the dynamic stability of the flow in the outlet channel by reducing the disturbing effect of the mass influx,

Claims (2)

1. A radial type chemical reactor containing coaxially placed gratings, between which a catalyst is located, distribution and discharge channels, characterized in that, in order to increase the yield of the product by reducing the likelihood of thermomechanical instability, the inner cylindrical grate is made in the form 0 hollow elements installed along generators and connected by means of manifolds to the inlet and outlet pipes of the refrigerant. 2. The reactor according to claim 1, characterized in that the hollow elements are made in the form coils. /// G x Pi s / / fifteen eleven /// /// /// // I Fig 1