DE3318098A1 - A process and reactor for carrying out an endothermic or exothermic reaction - Google Patents

Abstract

In a process for carrying out an endothermic or exothermic reaction, a reacting fluid 13 is passed in the radial direction through a reaction zone 2. Tubes 10 which serve for bearing a heating fluid or cooling fluid are incorporated in the reaction zone. The tubes extend in an axial preferential direction through the reaction zone (Figure 1). <IMAGE>

Description

Procedure and reactor for implementation

an endothermic or exothermic reaction The invention relates to a method to carry out an endothermic or exothermic reaction in which a reactive Fluid a reaction zone indirectly heated or cooled by a heating or cooling fluid flows through, the heating or cooling fluid 'in the preferred axial direction through the Flows reaction zone, as well as a reactor for carrying out the process.

Such a method is already known for synthesis reactions. For example, DE-OS 30 07 202 shows a reactor for carrying out a methanol synthesis with a cylindrical reaction zone covered with a bed of catalyst particles is filled. The synthesis gas is passed through the reaction zone in the axial direction. Pipes for guiding a cooling fluid are arranged in the catalyst bed, -through which dissipates the heat released during the reaction. The pipes are up A core tube is wound and the synthesis gas flows essentially across it.

The preferred direction of flow for the cooling fluid is axial Direction, so that the cooling fluid flows parallel to or in countercurrent to the synthesis gas. In this procedure becomes largely isothermal in the reaction zone Temperature profile achieved.

However, in this process, due to the flow conditions a large pressure drop for the synthesis gas as it passes through the reaction zone be accepted.

In addition to the energetic disadvantages that this pressure loss entails brings, is also the maximum possible size of the reactor due to the pressure drop limited.

The invention is therefore based on the object of a method of To develop the type mentioned at the beginning, with a low pressure drop of the reacting Fluids can be carried out and that also enables the processing of large amounts of fluid.

the advantageous approximately isothermal temperature profile in the reaction chamber should be preserved.

According to the invention, this object is achieved in that the reacting Fluid is passed in the radial direction through the reaction zone.

In the method according to the invention, the supply or discharge takes place of the reacting fluid or the reaction product on the circumference of the reaction zone, while the discharge or supply of the reaction product or the reacting fluid takes place in the axis of the reaction zone. Advantageously, it is reactive Fluid out in such a way that the cold end "of the reaction process at the periphery so that the outer jacket of the reactor is not exposed to high temperatures. This means that in the event of an exothermic reaction, the reacting fluid is advantageous is guided radially from the outside to the inside, while vice versa in the case of an endothermic Reaction, the reacting fluid is advantageously guided radially from the inside to the outside.

The implementation of the method according to the invention enables retention the largely isothermal temperature profile in the reaction zone, with now however, the pressure drop experienced by the reacting fluid as it passes through the reaction zone suffers, is minimized and no longer depends on the length of the reactor. Even in the case of very large reactor units, therefore, with a fixed reactor cross-section, a low pressure drop obtained. The flow guidance according to the invention results in high Heat coefficient, reduces the risk of overheating in the reaction zone ("hot spots") and reduces the temperature gradients in the reaction zone.

The method according to the invention is suitable for both implementation catalytic reactions, such as syntheses, as well as non-catalytic reactions, such as cleavage reactions.

It proves to be advantageous if, in a further embodiment of the The method according to the invention, the reacting fluid at least two axially from each other flows through separate reaction sub-zones. Here, depending on the process conditions, the reacting fluid passed in parallel through the reaction sub-zones or it flows through the sub-zones one after the other in a zigzag pattern.

The division of the reaction zone into several sub-zones offers the Advantage that different temperature ranges can be set in the reaction zone. The temperature can be set, for example, by varying the local density of the cooling surface vary. In this way, a conversion temperature profile is achieved that corresponds to the respective procedural and / or economic process optimal conditions closest comes.

It can prove to be useful if the rea- yawing Fluid mixed in after flowing through a partial reaction zone, cold unreacted fluid will.

In a further development of the method according to the invention, it is proposed that that reacted portions of the fluid before entry into the second partial reaction zone be separated.

Using the example of a catalyzed synthesis of SO2 from a mixture of SO31 ° 2 and inert gases, this means that what is formed in the first partial reaction zone S03 is separated from the gas stream before it enters the second partial reaction zone is directed.

The invention also relates to a reactor for carrying out the Process according to the invention with a reaction zone and with in the reaction zone extending pipes for guiding a heating or cooling fluid, which in a preferred direction run, as well as with facilities for the supply of a reactive and for discharge a reacted fluid which is characterized in that the means for feeding and the devices for discharging in planes perpendicular to the preferred direction the tubes are arranged.

According to a preferred embodiment of the reactor according to the invention is a first device for supply and discharge through a flow space on the circumference the reaction zone formed by a jacket provided with passage openings the reaction zone is separated. The jacket is expediently at a distance arranged to the housing of the reactor and forms with this a flow space of annular cross-section.

In a further advantageous embodiment, a second supply or discharge through a flow space inside the reaction zone, the through a with Central tube provided with passage openings from the surrounding reaction zone is separated.

It has proven to be advantageous if the central tube also functions as the winding core is designed for the heating or cooling pipes.

In an advantageous further development of the subject matter of the invention, it is proposed that that in the reaction zone at least one perpendicular to the axial direction Partition is arranged.

It also proves to be expedient if the heating or cooling surface density varies in the reaction zone.

The local temperature can be better on the-from by means of this measure Process sequence her most favorable value can be set.

A different cooling surface density can be achieved, for example achieve that pipes with different diameters and / or different mutual spacing and / or different cooling fins or cooling fins are used will.

In a preferred embodiment of the reactor according to the invention the reaction zone contains a bed of catalyst.

The reactor according to the invention is preferably suitable for reactors with rapid product formation, those with a relatively short flow-through reaction zone get by, and the large flow cross-sections to achieve large amounts of product require. An example of such a reaction is the synthesis of SO3 from SO2.

Further application examples for the reactor according to the invention are Methanol synthesis, ammonia synthesis, formaldehyde production, gasoline production from methanol, Methanation and CO shift The invention and further details of the invention are explained in more detail with the aid of schematically illustrated exemplary embodiments.

The figures show: FIG. 1 a reactor according to the invention in longitudinal section FIG. 2 shows a further embodiment of a reactor according to the invention in longitudinal section FIG. 3 shows a section of a reactor according to the invention with an associated one Temperature profile.

The reactor shown in Figure 1 has a housing 1 in which a catalyst bed is arranged. The housing 1 contains a filling opening 3 and an emptying opening 4 for the catalyst bed 2. Above and below the catalyst bed 2 is filled with inert material 5 in order to avoid bypasses and. to save expensive catalyst material.

The catalyst bed is on its outer circumference by a Passage openings provided jacket 6 limited, for example made of perforated plate and a mesh screen. The jacket 6 is arranged at a distance from the housing 1 and forms with this together a space 7 with an annular cross-section. In the room 7 open out connection 8 for the supply of a reactive fluid. Inside the catalyst bed 2, a central tube 9 is arranged, which in the area of the catalyst bed 2 with Perforations' is provided. The central tube 9 is on its upper side closed while it is passed down through the housing 1 to the outside and as a discharge opening is designed for reactive fluid.

Within the catalyst bed 2 pipes 10 are arranged, which are combined at their ends in pipe collectors 11, 1 2. The tubes 10 run straight in the embodiment shown, the tubes could just as well be wrapped around the central tube 9. The tubes 10 are used to guide a heating or cooling fluids, depending on whether there is an endothermic or an exothermic reaction in the reactor to be held. In any case, the preferred direction of flow runs into the Tubes 10 guided fluids in the axial direction.

If an exothermic synthesis reaction is carried out in the reactor according to the invention, e.g. a methanol or NH3 synthesis is carried out, the reacting fluid, which is at a lower temperature than the reaction product over which Nozzle 8 supplied. The fluid is initially distributed evenly in the space 7 and then flows through the catalyst bed 2 in the radial direction of outwards inwards, as indicated by arrows 13. The one with the catalytic Heat released from synthesis is removed from cooling fluid carried in tubes 10, e.g. evaporating water, absorbed and discharged. The course of the cooling fluid is through Arrows 14 indicated. After flowing through the reaction zone, the reacted arrives Fluid into the interior of the central tube 9 and leaves the reactor through this downwards.

This process management in an exothermic reaction offers the Advantage that the housing 1 by the reacting fluid, which is on a relatively low temperature is being cooled. If, on the other hand, a endothermic Reaction carried out in which the reacted fluid is at a lower temperature as the reacting Fluid.befindet, the flow direction of the reacting fluid is reversed, i.e. the reacting fluid is via the central tube 9 and flows through the catalyst bed 2 from the inside to the outside then leave the reactor via the nozzle 8.

In principle, it is also possible to stand the reactor upside down to operate, i.e. to arrange the nozzle 8 in the lower area and the central pipe 9 to lead up from the reactor.

Figure 2 shows a schematic representation of an inventive Reactor similar to that of Figure 1, but with the difference that the catalyst bed 2 by partition walls 15, 16 in three axially separated sections 17, 18, 19 is divided, form the reaction sub-zones. The upper partition 15 is sufficient outside up to the housing wall, while it ends inside at the central tube 9. The lower one Partition wall 16 ends on the outside of the jacket 6 and extends over the entire inside Cross section of the central tube 9. In this way, the supplied through the nozzle 8 is Fluid sequentially along arrows 20 on a zigzag flow path passed through the three sections 17, 18, 19 of the catalyst bed 2. The reaction zone is thereby extended. If necessary, different partial reaction zones can be used in the individual reaction zones Set cooling surface densities, for example by applying cooling fins or Cooling fins on the tubes 10. An arrangement is also conceivable in which the Partition walls only extend over the cross-sectional area of the catalyst bed 2, so that the sections of the catalyst bed lying between the partition walls are flowed through in parallel by the reacting fluid.

In the embodiment shown in Figure 2, the Fluid 20 after flowing through the first section 17 and / or the second section 18 cold unreacted gas mixed in to achieve additional cooling and to make better use of the catalyst. The supply takes place, for example Via gas supply devices (not shown in FIG. 2) into the central pipe 9 or in the space 7 below the partition 15.

FIG. 3 shows a section from the catalyst bed of a reactor according to the invention, the density of the cooling tubes 10 being here in the direction of flow of the reacting fluid changes. Below this section is the temperature profile of the reacting fluid on its way through the catalyst bed 2. The reacting fluid enters the reaction zone at temperature T E and heats up considerably as a result of the reaction that starts. The heat of reaction is of the Discharged cooling fluid which has a temperature TK. In the area where the Maximum temperature TM is to be expected, the pipe spacing is reduced by the heating surface density to increase and to overheating of the catalyst and / or undesired accompanying reactions to prevent. The outlet temperature is TA

Claims (11)

Claims method for performing an endothermic or exothermic Reaction in which a reacting fluid is indirectly heated by a heating or cooling fluid heated or cooled reaction zone flows through, wherein the heating oder'Kühlfluid flows through the reaction zone in the preferred axial direction, characterized in that that the reacting fluid is passed in the radial direction through the reaction zone 2. The method according to claim 1, characterized in that the reactive fluid flows through at least two axially separated partial reaction zones. 3 'method according to claim 2, characterized in that the reacting Fluid mixed in after flowing through a partial reaction zone, cold unreacted fluid will. 4. The method according to claim 2 or 3, characterized in that before entry into the second partial reaction zone, reacted fractions are separated from the fluid will. 5. Reactor for carrying out the method according to claim 1 with a Reaction zone and with pipes running in the reaction zone for guiding a Heating or cooling fluids that run in a preferred direction, as well as with devices for supplying a reacting fluid and for discharging a reacting fluid, thereby characterized in that the device for supply and the device for removal are arranged in planes perpendicular to the preferred direction of the tubes (10). 6. Reactor according to claim 5, characterized in that a first Device for supply or discharge through a flow space (7) on the circumference of the reaction zone is formed by a jacket (6) provided with passage openings from the Reaction zone is separated. 7. Reactor according to claim 5 or 6, characterized in that a second feed or discharge through a flow space in the interior of the reaction zone is formed by a central tube (9) provided with passage openings of the surrounding reaction zone is separated. 8. Reactor according to claim 7, characterized in that the central tube (9) is also designed as a winding core for the heating or cooling pipes (10). 9. Reactor according to one of claims 5 to 8, characterized in that that in the reaction zone at least one perpendicular to the axial direction Partition (15, 16). Is arranged. 10. Reactor according to one of claims 5 to 9, characterized in that that the heating or cooling surface density varies in the reaction zone. 11. Reactor according to one of claims 1 to 10, characterized in that that the reaction zone contains a bed of catalyst (2).