RADIAL FLOW HORIZONTAL CATALYTIC REACTOR

Abstract

Horizontal adiabatic reactor (1) for heterogeneous catalytic reactions, comprising an outer cylindrical shell (2), an inlet (6) for reagent gases and an outlet (7) for gaseous products, a basket (10, 13) containing a catalytic bed (5a, 5b) positioned horizontally inside said reactor, wherein said reactor is configured in such a way that the gases cross said catalytic bed in a radial or axial-radial manner, said shell (2) has a cover (4) which can be opened and which defines an opening (20), and said basket (10, 13) is extractable horizontally from said opening.

Claims

1. Horizontal adiabatic reactor (1) for heterogeneous catalytic reactions, comprising: a cylindrical outer shell (2), an inlet (6) for a flow of reagent gases and an outlet (7) for a flow of gaseous products; at least one basket (10, 13) containing at least one catalytic bed (5a, 5b), said catalytic bed being positioned horizontally inside said reactor; characterized in that: said reactor is configured in such a way that said gas flow crosses said at least one catalytic bed in a radial or axial-radial manner; and said shell (2) has a cover (4) which can be opened and defines an opening (20) and said basket (10, 13) can be extracted horizontally from said opening.

2. Reactor according to claim 1, characterized in that said at least one catalytic bed (5a, 5b) has an annular configuration and radial symmetry.

3. Reactor according to claim 1, characterized in that said at least one catalytic bed has cylindrical inlet surfaces and outlet surfaces for said reagents and gaseous products, respectively.

4. Reactor according to claim 3, characterized in that said surfaces are defined by gas-permeable coaxial walls for containing the bed.

5. Reactor according to any one of the preceding claims, characterized in that said at least one basket (10, 13) is slidable along at least one linear guide.

6. Reactor according to any one of the preceding claims, comprising a first catalytic bed (5a) in the centre of which a coaxial heat exchanger (9) is housed, and a second catalytic bed (5b) in the centre of which a coaxial gas discharge tube (8) is housed.

7. Reactor according to claim 6, characterized in that said at least one basket (10,13) is delimited by an inner cylindrical wall (11, 14) and by an outer cylindrical wall (12, 15) which are at least partly permeable to said gas flows such that an axial or axial-radial flow crosses the catalytic bed.

8. Method for replacing catalyst in an adiabatic horizontal catalytic reactor according to claim 1, characterized by the following operations: horizontally extracting said basket (10, 13) from said shell (2); vertically positioning said basket; removing the used catalyst from said basket in a vertical position; inserting fresh catalyst inside said basket in a vertical position; and reintroducing said basket in a horizontal position and inserting it inside the shell.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] FIG. 1 shows a diagrammatic longitudinally sectioned view of the reactor in accordance with the present invention.

[0035] FIG. 2 shows a diagrammatic cross-sectional view of the reactor according to

[0036] FIG. 1 along the cross-sectional plane II-II.

[0037] FIG. 3 shows a diagrammatic cross-sectional view of the reactor according to FIG. 1 along the cross-sectional plane III-III.

[0038] FIG. 4 shows the sequence of operations for loading and unloading the catalyst into/from the reactor.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0039] FIG. 1 shows a horizontal adiabatic reactor 1 which comprises a cylindrical shell 2, with a longitudinal axis A-A enclosed by a base 3 welded to the shell 2 and by a cover 4 which can be opened and is flanged together with the shell 2.

[0040] The reactor comprises, in the example shown, two catalytic beds 5a and 5b with annular configuration and radial symmetry; it further comprises an inlet 6 for a gaseous flow of reagents and an outlet 7 for gaseous reaction products, said outlet 7 communicating with a header 8 coaxial with the second catalytic bed 5b. An inter-cooling heat exchanger 9 is instead arranged in the centre of the first catalytic bed 5a.

[0041] The first catalytic bed 5a is contained inside a basket 10 and is delimited by an outer cylindrical wall 11 and an inner cylindrical wall 12. Both said walls 11 and 12 are gas-permeable, for example perforated. Similarly, the second catalytic bed 5b is contained inside a basket 13 and is delimited by gas-permeable cylindrical walls 14, 15.

[0042] Said reactor 1 is configured in such a way that the gas flow entering the inlet 6 crosses the catalytic beds in a radial or axial-radial manner. In particular, said incoming flow travels along a space 10 around the catalytic beds (cooling the walls of the shell 2), and then enters the bed 5a via the perforated wall 11 and crosses the bed 5a with a centripetal radial flow.

[0043] In order to obtain an axial-radial flow, the surface 11 is gas-permeable, while a portion of the wall 11, for example the strip 11 on the right-hand side in FIG. 1, is gas-impermeable (not perforated). In this way a part of the gas enters the bed axially across the surface 11.

[0044] The flow leaving the first catalytic bed 5a, via the inner wall 12, passes into the shell side of the heat exchanger 9, where it is cooled releasing heat to a fluid entering via the connection 17, and is then conveyed to the second bed 5b. Said second bed 5b is also crossed with a centripetal radial or axial-radial flow, with inflow via the outer wall 14 and outflow via the inner wall 15 such that the reaction products are collected inside the outlet header 8.

[0045] Examples of embodiments of walls permeable to a gas flow and designed to contain a catalyst mass are described for example in EP 1818094 and EP 2014356.

[0046] The baskets 10 and 13 are extractable from the shell 2. Said baskets 10, 13 are preferably slidable on linear guides such as, for example, one or more longitudinal rails. For example FIG. 1 shows a guide wheel or roller 18.

[0047] FIG. 4 shows the sequence of operations for changing the catalyst contained inside the first catalytic bed 5a.

[0048] FIG. 4 A) shows the reactor 1, once the cover 4 has been removed. Said cover is of the fully opening type, namely it has the same diameter as the shell 2 and consequently its removal allows the basket 10 to be extracted from the opening 20, as can be seen in FIG. 4B).

[0049] From this position, the basket 10 can be freed by removing the existing mechanical and/or fluid connections which fasten it to the basket 13 of the second bed and separating the basket from the reactor as shown in FIGS. 4C) and D).

[0050] The basket extracted from the reactor may be arranged vertically, rotating it through 90 degrees for the operations of replacement of the catalyst. In particular, FIG. 4F) shows the unloading of the old catalyst which is performed from the bottom, through at least one discharge nozzle 19; FIG. 4G) shows the insertion of new catalyst which is poured in from above into the basket. Said operations may be performed using the known vertical reactor techniques.

[0051] The second catalytic bed 5b and associated basket 13 may be extracted for replacement of the catalyst using a similar procedure.

[0052] In a preferred embodiment said heat exchanger 9 uses water as a cooling fluid, with the production of steam which is used in other parts of the plant. As an alternative, said heat exchanger 8 may use as cooling fluid part of the cold gaseous reagents, therefore acting as a preheating system for said gaseous reagents.

[0053] It may be noted that the inlet and outlet sections of the catalytic beds are cylindrical walls, thus avoiding the risks of catalyst fluidization which were mentioned above and which affect the horizontal reactors of the prior art.

[0054] The radial or axial-radial flow allows to obtain a uniform flow of the gas inside the catalytic bed, therefore control over the optimum temperature and a high heat exchange. It ensures moreover a uniform distribution of the gas as in vertically arranged reactors.