Catalytic reactor for endothermic reactions

Details Catalytic reactor for endothermic reactions Catalytic reactor for endothermic reactions

1996-04-09

1999-08-10

Tran, Hien

Chemical apparatus and process disinfecting, deodorizing, preser

Chemical reactor

Including heat exchanger for reaction chamber or reactants...

422171, 422177, 422198, 422204, 422205, B01J 806, C01B 338

Patent

active

059355310

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention is directed to a catalytic reactor. For endothermic reactions. Examples of such reactions are the production of hydrogen by steam reformation of hydrocarbons and dehydrogenation processes that are carried out, e.g., for the production of styrene from ethylbenzene or of propylene from isobutane.
2. Description of the Prior Art
A catalytic reactor having an external cylindrical shape and a reaction chamber with a circular cross section is known from EP 0 380 192 B1. The input material to be catalyzed is introduced from the bottom into the reaction chamber which is filled with a catalytic material, while the obtained catalytically converted product is extracted from the upper end of the reaction chamber. This known reactor is heatable by means of a burner which is arranged below the base level of the reaction chamber and enclosed in the region of its combustion zone by a refractory shell. The flame direction of the burner is oriented coaxially to the longitudinal direction of the reaction chamber. The ascending combustion gases of the burner are guided along virtually the entire length of the reaction chamber in a heat distributor which is formed as a tubular body from a material with good heat conduction and directly adjoins the refractory combustion chamber wall. An annular gap remains open between the tubular heat distributor and the inner defining wall of the annular reaction chamber. The occurring hot combustion gases are therefore first guided upward by the heat distributor and are deflected into the annular gap at the upper end of the heat distributor. The combustion gases then flow downward through the annular gap and, in so doing, give off heat into the reaction space through the inner defining wall. At the same time, however, the combustion gases flowing downward past the wall of the heat distributor also absorb heat from the hot combustion gases flowing upward in the interior of the heat distributor so that the temperature of the gases in the annular gap remains virtually constant. In this way, the known device can be operated as an isothermal reactor in practice.
In another embodiment form, the reactor known from EP 0 380 192 B1 has a plurality of parallel heat distributors arranged in place of a central heat distributor. There is also only one burner provided in this device, this burner being arranged with its combustion space below the base level of the reaction chamber. Since practically no heat is given off externally in the combustion space itself, the combustion of the fuel used in each case takes place under adiabatic conditions so that, depending on the fuel, undesirably high flame temperatures are reached. In order to decrease the temperature of the combustion gases, the conventional amount of approximately 10% excess air can be considerably increased, e.g., to 50%. However, this leads to a compulsory corresponding increase in the amount of exhaust gas with the consequent heat losses, which is also undesirable. As an alternative to a reduction in temperature, EP 0 380 192 B1 proposes a return of exhaust gas to the combustion zone. This has the particular disadvantage of additional construction costs.
Another endothermic reactor is known from EP 0 369 556 B1. The reaction chamber of this reactor, which is filled with a catalyst, is designed as a tubular shell or sheathing tube which is closed at the bottom end. An ascending pipe is inserted into the latter in such a way that the material to be processed can flow in opposite directions through the annular space between the sheathing pipe and the ascending pipe, on the one hand, and through the ascending pipe, on the other hand, in order to pass the reaction space. In this apparatus, the hot combustion gas for heating the reaction space is generated in a separate part of the installation under adiabatic conditions and is subsequently introduced laterally into the refractory housing in the lower end region of the reaction space, this housing enclosing the reactor externally

REFERENCES:
patent: 4999089 (1991-03-01), Nakase et al.
patent: 5162104 (1992-11-01), Bezzeccheri et al.
patent: 5219535 (1993-06-01), Giacobbe et al.
patent: 5429809 (1995-07-01), Stahl et al.

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