DE2504343C2 - Process and reactor for carrying out exothermic catalytic reactions - Google Patents

Description

The invention relates to a method for the exothermic catalytic conversion of a feed medium into a catalyst system consisting of one or more layers, in which the feed medium is in at least two substreams is divided, the first substream having the catalyst system in its flows through the entire length and the further partial flow or the further partial flows individually at different Places are introduced into the catalyst system.

From DE-AS 17 67 355 such a method known It has three mutually independent

ίο Catalyst layers on, between the other components are switched. The feed stream is divided into two substreams, one of which is initially through indirect heat exchange with hot reaction products and then preheated through the whole

: 5 catalyst system is performed. The second partial flow, which in turn can be divided into partial flows, is used without preheating the first partial flow as a cooling medium before the first and / or second catalyst layer mixed in. An essential feature of this known method is that part of the a reaction zone exiting reaction product circulated and in an injector with preheated fresh gas or a gas mixture emerging from a previous reaction stage and then fed back to the reaction zone.

This known method proves to be disadvantageous in that it is complicated and therefore prone to failure Procedural requires. In addition, the Dissipation of the heat of reaction by heat exchange with the feed stream, as it takes place here in the Carrying out strongly exothermic reactions is always associated with risks, since a reliable protection against a Damage to the reactor through inadmissible temperature rise is hardly possible if the coolant at the same time is the feed stream.

Furthermore, from US-PS 31 28 163 a method is known in which a gas mixture in a reactor with several catalyst layers is introduced in order to be subjected to an exothermic reaction there.

The heat of reaction released in the process becomes part of it delivered to a medium that is introduced at one or more points between the catalyst layers is, and that is able to due to endothermic processes such. B. evaporation or thermal Cleavage to absorb heat. This process is therefore a combination of the exothermic reaction with an endothermic process in which a direct heat exchange takes place.

This process has the disadvantage that it is introduced into the reaction mixture to absorb heat Medium has to be removed from the end product with some effort if it is not in it is desired. In addition, a suitable medium must be used for each desired temperature range this area has endothermic change of state, or a suitable mixture, its components endothermic reacting with one another in this area can be found. These disadvantages limit that Procedure in its applicability and in its economic efficiency.

Furthermore, from DE-OS 14 42 750 a method for regulating the temperature within a multilayer Catalyst system for the implementation of

. Exothermic high pressure reactions known in which the hot gas mixture emerging from a reaction zone is divided into two partial flows, one of which is fed to indirect cooling. After this the product streams are reunited, they become the

This process provides information on the conduct of the process according to the invention Neither can be found in that from DE-AS 22 21 288 or from US Pat. No. 3,751,232 known procedures. DE-AS 22 21 288 shows only a reactor with several catalyst zones, between each of which heat exchangers are provided for cooling the reaction product. It is essential that the coolant circuits can be regulated individually, but all of them are connected to a main coolant circuit are connected. The US-PS 37 51 232 finally shows a reactor with a single annular Katäiysatorschicht from an undivided feed stream is flowed through several times in the radial direction. The multiple flow is through accordingly arranged baffles ensured It is mentioned that for temperature control at Hydrogenation reactions are fed cold hydrogen after each pass through the catalyst system can.

The present invention has the object based on developing a process of the type mentioned above that is as economical as possible in its Working method and as comprehensive as possible in its applicability

This object is achieved in that at the same time the heat of reaction at least partially through indirect Heat exchange dissipated with a cooling medium within the catalyst layers and furthermore Cooling medium is passed through the catalyst layers in cross-flow to the feed medium.

The process according to the invention enables the thermal conditions in the reactor to be controlled possible in a particularly flexible way and. at the same time a particularly effective reaction procedure is ensured The heat dissipation by indirect heat exchange with a coolant has the advantage that the for the Heat absorption favorable temperature range, e.g. B. with an evaporating cooling medium, by pressure change can be shifted within wide limits. In the case of a multi-zone catalyst system, the Step-by-step supply of the input medium is also possible by letting it out or switching it on again one or more catalyst zones to achieve better adaptation to load fluctuations.

The routing of the cooling medium in a cross flow to the input medium offers some essential advantages compared to the usual guidance of the coolant in simple countercurrent. The indirect heat exchange between the coolant and the reaction gas is namely when the corresponding flows are guided in a cross-flow manner cheaper than with parallel guidance, and the unwanted pipe wall flow is also eliminated.

The process according to the invention can advantageously be applied to the generation of a methane-rich gas from a gas mixture consisting essentially of carbon oxides and hydrogen in the presence of water vapor, the carbon oxides being converted by conversion and methanation. _w

It can also be used with advantage to carry out other exothermic reactions, such as. B. the extraction of methanol from hydrogen and carbon monoxide or formaldehyde from methanol and oxygen or air can be used. _ω

To carry out exothermic reactions in the manner described above, it is advantageous to use a To use the reactor, which is in the manner of a wound tube bundle heat exchanger with a winding core tube is formed, wherein the wound tubes are used to guide the cooling medium, the catalyst system is arranged in the outer space of the tubes and gas supply tubes open into the catalyst system.

Compared to the usual reactors, in which the catalysts are filled into straight reaction tubes and the cooling medium flows in the outer space, such a reactor offers some essential advantages. Of the indirect heat exchange between coolant and reaction gas is appropriate when guiding Cross-flow flows are cheaper than parallel flow. The unwanted pipe wall flow as shown in pipes filled with catalyst occurs is eliminated. Furthermore, the repair of leaks is on relatively easy to achieve by closing individual tubes. This affects the operation of the Reactor not because there is only a minor intervention in the cooling 'system while in the case of with Catalyst-filled tubes in r. ', Ii reaction process would intervene. At Vertciirng the Kaiaiyxatorniasse in the outer space of the tubes there can also be a significantly larger catalyst volume in the reactor be accommodated. By reducing the pipe diameter and increasing the number of pipes, a larger heat exchange surface can be made available. But while when filled with catalyst Pipes the reduction of the pipe diameter by the nature of the catalyst filling as well as the Pipe wall flow limits are set, this is not the case in the reactor according to the invention, since a Reduction of the pipe diameter here by increasing the flow rate of the cooling medium can be easily compensated for.

For the purpose of supplying the further substreams in the catalyst system, the reactor is also designed so that between the wound pipe layers in axial direction gas supply pipes are arranged, which open in groups into the catalyst system. In particular, in the case of a reactor with webs arranged in the axial direction between the pipe layers be advantageous that at least a certain number of the webs is designed as gas supply pipes. Through this the necessary mechanical stability is guaranteed, while space can be saved at the same time.

With regard to the gas supply pipes combined in groups, it is expedient if the gas supply pipes are brought together outside the tube bundle to form manifolds. There is the possibility that the headers are arranged in the radial direction, and that at least a certain number of the headers opens outside the Recktormantels in an annular tube surrounding the jacket, in particular it can be provided that at least a certain number of the radial headers into the winding core opens which is connected to a feed pipe passed through the reactor jacket. Furthermore, for the arrangement of the manifolds there is the possibility that the manifolds within the reactor are annular pipes arranged concentrically about its longitudinal axis, which are connected to supply pipes passed through the reactor jacket.

Furthermore, it can be useful that radially through the reactor jacket into the interior of the Catalyst system are led into gas supply pipes, the walls of which have openings distributed like a sieve

exhibit.

Further details can be found in the figures explained below:

Fig. 1 illustrates schematically the procedure according to the invention, in particular the management of the input and cooling media.

The F i g. 2 to 6 show schematically different embodiments of the reactor according to the invention. These are essentially variants in the manner in which the further streams of oil are supplied. The catalysts are shown in FIGS. 2 to 6 not shown.

In Fig. 1, a catalyst system 2, 3, 4 structured in layers is arranged within a reactor 1. A cooling medium flows in cooling coils 5, 6, 7 in indirect heat exchange with the catalyst system and the feed medium heated by the reaction. The entire Einsat7: medium is conveyed through line 8 brought up and in a first partial stream 9 and several other partial streams flowing in line OK divided, the first substream 9 flowing through the catalyst system 2,3.4 in its entire length and the other substreams are fed to the catalyst system at various points. The entire Feed medium leaves reactor 1 after the reaction through line 11.

In Fig. 2 are tubes of a tube bundle 22 at 23 and 24 passed through a reactor jacket 21. The tube bundle is wound around a winding core tube 25. Between the pipe layers protrude axially In the direction of gas feed pipes 26, 27 that feed the further partial flows of the input medium to serve. The gas supply pipes are grouped into groups of different lengths, each of special manifolds 28, 29 are branched off. In the case of FIG. 2, the collecting pipes follow radially outside through the reactor jacket 21. they are Distributed in a star shape over the circumference and flow into Annular tubes 30, 31 a. which are led around the reactor jacket. Each of these ring tubes becomes a Part of the Saizmediums fed into the gas supply pipes. which can also be designed as webs. However, since they generally end at different heights within the tube bundle, they can do not completely replace conventional bars.

The reactor can consist of several tube bundles that follow one another in the axial direction. Not that one The catalyst system shown is expedient

s be constructed in such a way that a catalyst layer is assigned to each tube bundle, the catalyst mass in close contact in the outer space of the tubes is arranged with these. The indirect heat exchange takes place between that flowing in the pipes

ίο Cooling medium on the one hand and the heated catalyst mass and the one heated by the reaction ninsalzmedium on the other hand instead.

In Fig. 3, the annular tube 30 of FIG. 2 through a Feed pipe 33 replaced by the reactor jacket is passed and with a chamber 32 of the Winding core tube 25 is in communication. The radial manifolds 28 also open into this chamber. which alternate with the manifolds 29 over the circumference.

in Fig. 4 simi the tu "Jen groups of gas / .ufiinrungsrohren 26, 27 belonging collecting pipes 34, 35 is not radially outwardly guided, but concentric to the reactor longitudinal axis of annular pipes, of which in turn supply pipes 36 branch off 37 defined by the

Reactor jacket are passed through to the outside.

The reactor in the embodiment according to FIG. 5 owns no manifolds inside the reactor jacket. A certain amount of the number of pipe layers flows here dependent: number of gas supply pipes 26, 27 side by side directly in the reactor jacket, whereby these tube groups are in turn distributed in a star shape over the circumference.

In the embodiment according to FIG. 6 is the principle the axial, possibly through manifolds too Groups combined gas supply pipes replaced by another: The other partial flows of the feed medium are here by specially designed, radially through the reactor jacket inside leading gas supply pipes 40, 41 in the Fed into the reactor, the surface of which has openings distributed like a sieve. As a result, in the area of Gas supply pipes 40, 41 themselves ensure a uniform distribution of the input medium supplied

For this purpose 3 sheets of drawings

Claims (9)

Patent claims: 1. Process for the exothermic catalytic conversion of a feed medium in one of one or; Catalyst system existing in the lower layers, in which the input medium is divided into at least two substreams, the first Partial stream flows through the catalyst system in its entire length and the further partial stream or the further substreams are introduced into the catalyst system at different points, thereby characterized in that at the same time the heat of reaction at least partially by indirect Heat exchange dissipated with a cooling medium within the catalyst layers and further the cooling medium is passed through the catalyst layers in cross-flow to the feed medium. 2. Reactor for performing the method according to claim 1, characterized in that the Reactor in the manner of a wound tube bundle heat exchanger is formed with a winding core tube (25), the wound tubes (22) for The catalyst system serves to guide the cooling medium is arranged in the outer space of the pipes (22) and gas supply pipes (26, 27, 40, 41) into the Open into the catalyst system. 3. Reactor according to claim 2, characterized in that the gas supply pipes (26, 27) are arranged between the wound pipe layers (22) in the axial direction and in groups in the Open into the catalyst system. 4. Reakto- according to claim 2 or 3 with arranged between the pipe layers in the axial direction Web, characterized in that at least a certain number of the webs as gas supply pipes is trained. 5. Reactor according to claim 3 or 4, characterized in that the gas supply pipes (26, 27) are brought together outside the tube bundle (22) to form manifolds (28,29,34,35). 6. Reactor according to claim 5, characterized in that the headers (28, 29) in radial Direction are arranged and that at least eip.e certain number of headers outside the Reactor jacket opens into an annular tube (30,31) surrounding the jacket. 7. Reactor according to claim 5, characterized in that the headers within the Reactor concentrically arranged around its longitudinal axis are annular tubes (34, 35) with through The feed pipes (36, 37) passed through the reactor jacket are connected. 8. Reactor according to claim 6, characterized in that at least a certain number of radial manifolds opens into the winding core tube (25), which with a through the reactor jacket is connected through feed pipe (33). 9. Reactor according to claim 2, characterized in that the gas supply pipes (40,41) through through the actuator jacket radially into the interior of the Catalyst system are led into it and have openings distributed like a sieve.