DE102016114563A1 - Apparatus and method for reforming a hydrocarbon - Google Patents

Abstract

The present invention relates to a device for reforming a hydrocarbon having a reaction tube for passing the hydrocarbon, a particulate catalyst bed arranged inside the reaction tube and a firing device arranged outside the reaction tube for heating the reaction tube, wherein at least one heat transfer element is transverse in one direction within the reaction tube is arranged to a longitudinal axis of the reaction tube, that it extends from a first inner side of the reaction tube to an opposite, second inner side of the reaction tube.

Description

State of the art

The present invention relates to a device for reforming a hydrocarbon with a reaction tube for passing the hydrocarbon, a particulate catalyst bed arranged inside the reaction tube and a firing device arranged outside the reaction tube for heating the reaction tube. Furthermore, the invention relates to a method for reforming a hydrocarbon, wherein the hydrocarbon is passed through a reaction tube, within which a particulate catalyst bed is arranged, and wherein the reaction tube is heated by a firing device arranged outside the reaction tube.

Such devices are also referred to as steam reformers and typically include multiple reaction tubes in which catalytic conversion of the hydrocarbons into a product occurs. In such devices, gaseous hydrocarbons, for example, with the addition of steam can be catalytically converted to synthesis gas, ie to mixtures of hydrogen and carbon monoxide. Further, in such devices, it is possible to react propane to form a propylene and hydrogen-enriched product stream.

In the reaction tubes of the device, a particulate catalyst bed is arranged, which is traversed by the hydrocarbon. Since the reactions are endothermic, the reaction tubes are heated from the outside by a firing device. The heat provided by the firing device is transferred to the catalyst bed via the wall of the reaction tube. It has proved to be disadvantageous that sets an uneven temperature distribution within the catalyst bed both in the axial and radial directions. This can lead to unwanted side reactions.

Disclosure of the invention

The object of the present invention is to reduce the likelihood that undesirable side reactions will occur in the reaction tubes.

The object is achieved by a device for reforming a hydrocarbon with a reaction tube for passing the hydrocarbon, a arranged inside the reaction tube, particulate catalyst bed and arranged outside the reaction tube firing device for heating the reaction tube, wherein within the reaction tube at least one heat transfer element so in one direction is arranged transversely to a longitudinal axis of the reaction tube, that it extends from a first inner side of the reaction tube to an opposite, second inner side of the reaction tube.

By means of the heat transfer element arranged inside the reaction tube, the heat, which is transmitted from the firing device from the outside to the reaction tube, can be conducted into the interior of the reaction tube. Since the heat transfer element extends from a first inner side of the reaction tube to an opposite, second inner side of the reaction tube, the heat transfer into the interior of the reaction tube can take place from two opposite sides of the reaction tube. In this respect, the heat transfer is promoted to the arranged inside the reaction tube catalyst bed and / or flowing through the reaction tube hydrocarbon. In a direction perpendicular to the flow direction of the hydrocarbon, a temperature profile can be achieved in the reaction tube, which has lower fluctuations compared to a known reaction tube without heat transfer elements. Due to the homogenized temperature distribution, the occurrence of undesirable side reactions can be reduced.

The reaction tube preferably has a round cross section. Alternatively, the reaction tube may have an oval, triangular, quadrangular or polygonal cross-section. The reaction tube may be formed of a metal, for example a steel. The heat transfer element is preferably formed of the same material as the reaction tube, for example of a steel. Particularly preferably, the heat transfer element is firmly connected to the reaction tube, in particular welded, so that the best possible heat transfer between the reaction tube and the heat transfer element can be achieved.

The device advantageously comprises a plurality of reaction tubes, so that a reaction throughput can be made possible, which corresponds to a multiple of a single reaction tube. The plurality of reaction tubes can be heated by the same firing device. It is preferable if a plurality of firing devices are provided to heat the single reaction tube or the plurality of reaction tubes. In an advantageous embodiment, several firing devices in a burner chamber of Device arranged, wherein the reaction tubes extend through the burner chamber. Here, the interior of the reaction tubes is preferably not in gas exchange with the burner chamber.

Further advantageous embodiments of the invention are the subject of the dependent claims and will be explained below.

An advantageous embodiment provides that the heat transfer element is formed as a plate, wherein a main extension plane of the plate is arranged perpendicular to the longitudinal axis of the reaction tube and wherein the plate has at least one opening for passage of the flow. Due to the plate-shaped configuration of the heat transfer element, an improved heat transfer from outside the reaction tube into the interior of the reaction tube can be made possible. The plate has at least one, preferably a plurality, openings through which the gaseous hydrocarbon can be passed. The openings may have a round, oval, angular or circular arc segment-shaped cross-section.

In this context, it has been found to be particularly advantageous if the opening to the inner wall of the reaction tube has a distance which is smaller than a distance of the opening to a central axis of the reaction tube. In this respect, the opening is arranged in an edge region of the plate formed as a heat transfer element. As a result, turbulence of the gaseous hydrocarbon can be formed near the inside of the reaction tube. Due to the turbulence, the time available for heat transfer from the reaction tube to the gaseous hydrocarbon is increased. This helps to transfer more heat from the reaction tube to the hydrocarbon. Preferably, a plurality of openings in the edge region of the plate are arranged, for example on a circular path, so that at several points of the edge region of the plate, preferably in the entire edge region of the plate, turbulence are generated.

According to an alternative, advantageous embodiment, the heat transfer element is designed as a network, so that the heat transfer element can deform in order to adapt to the catalyst bed.

A further alternative, advantageous embodiment provides that the heat transport element is designed as a wire. Preferably, a plurality of wires are arranged in the reaction tube.

An embodiment has proved to be advantageous in which the heat transport element has a cross-shaped cross section. The heat transfer member may have two intersecting struts each extending from an inner side of the reaction tube to an opposite inner side of the reaction tube. By the cross-shaped configuration, the stability of the reaction tube and / or the heat transfer element can be increased.

It is advantageous if the heat transfer element extends in a direction parallel to the longitudinal axis of the reaction tube, whereby an increased heat exchange between the heat transfer element and the catalyst bed can be made possible. The temperature distribution within the catalyst bed can consequently also be homogenized in a direction parallel to the longitudinal axis of the reaction tube. In addition, the heat transfer from the heat transfer element to the reaction gases can be improved. With the heat transport element, therefore, heat can be transported both in a direction perpendicular to the longitudinal axis of the reaction tube and in a direction parallel to the longitudinal axis.

Furthermore, it is advantageous if the heat transfer element is arranged within the catalyst bed so that a direct transfer of heat from the heat transfer element to the catalyst bed, in particular the individual particles of the catalyst bed, is made possible. Preferably, the heat transfer element is completely enclosed by the catalyst bed.

A preferred embodiment provides that a particulate heat-conducting material is arranged within the catalyst bed, wherein the particulate heat-conducting material has a higher thermal conductivity than the catalyst bed. For example, the thermal conductivity of the Wärmeleitmaterials be greater than the thermal conductivity of the material of the catalyst bed.

It is advantageous if a plurality of heat transfer elements are arranged in the reaction tube, so that at several points in the reaction tube, the heat transfer between the reaction tube and the catalyst bed is increased. The plurality of heat transfer elements are preferably arranged within the catalyst bed.

To solve the object mentioned above also contributes to a method for reforming a hydrocarbon, wherein the hydrocarbon is passed through a reaction tube, within which a particulate catalyst bed is arranged, wherein the reaction tube is heated by an outside of the reaction tube firing device, and wherein within the Reaction tube at least one Heat transfer element is arranged such that extends from a first side of the inner wall of the reaction tube to an opposite side of the inner wall.

In the method, the same advantages can be achieved as have already been described in connection with the device.

Further details, features and advantages of the invention will become apparent from the drawings, as well as from the following description of preferred embodiments with reference to the drawings. The drawings illustrate only exemplary embodiments of the invention, which do not limit the inventive concept.

Brief description of the figures

The 1 shows a device according to an embodiment of the invention in a perspective sectional view.

The 2 shows a first embodiment of a reaction tube according to the invention with a heat transfer element in an exploded perspective view.

The 3 shows a second embodiment of a reaction tube according to the invention with a heat transfer element in a perspective view.

The 4 shows a third embodiment of a reaction tube according to the invention with a heat transfer element in a perspective view.

The 5 shows a fourth embodiment of a reaction tube according to the invention with a heat transfer element in a side sectional view.

The 6 shows the reaction tube according to 5 in a top view.

The 7 shows a fifth embodiment of a reaction tube according to the invention with a heat transfer element in a side sectional view.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference numerals and are therefore usually named or mentioned only once in each case.

In the 1 is a device designed as a steam reformer 1 for reforming a hydrocarbon with multiple reaction tubes 2 shown for passing the hydrocarbon. Inside the reaction tubes 2 is a particulate catalyst bed 3 arranged. For heating the reaction tubes 2 from the outside, a number of firing devices designed as burners are located outside the reaction tubes 4 arranged. The firing devices 4 are located on the ceiling of a burner chamber 5 , The burner chamber 5 is from the inside of the reaction tubes 2 gas-tight isolated. However, it takes over the wall of the reaction tubes 2 a heat exchange between the combustion chamber 5 and the interior of the reaction tubes 2 instead, leaving the inside of the reaction tubes 2 can be heated.

The reaction tubes 2 are at their upper end each with an input header 6 connected, via which they are charged with hydrocarbon and / or steam. At its lower end are the reaction tubes 2 each with an output bus 7 connected, via which the product gases are discharged.

Inside the reaction tubes 2 each is at least one heat transfer element 10 arranged, through which the heat transfer from the walls of the reaction tubes 2 into the interior and in particular to the catalyst bed 3 is increased. Based on 2 to 7 Below are some embodiments of such heat transfer elements 10 to be discribed.

In 2 is a first embodiment of a reaction tube 2 with two heat transfer elements 10 shown. The heat transfer elements 10 are inside the reaction tube 2 such in a direction Q transverse to a longitudinal axis L of the reaction tube 2 arranged that they are from a first inside of the reaction tube 2 to an opposite, second inside of the reaction tube 2 extend. In the 2 shown longitudinal axis L coincides with the central axis M of the reaction tube 2 together, which through the cross-sectional center of the reaction tube 2 runs. The reaction tube 2 is designed as a cylindrical round tube. The heat transfer elements 10 are formed as plates, which have a round cross section, which on the inner cross section of the cylindrical reaction tube 2 is adjusted. The main extension plane of the plate is perpendicular to the longitudinal axis L of the reaction tube 2 arranged. For passage of the hydrocarbon, the plate has a plurality of openings 11 on.

At the top of the 2 illustrated heat transfer element 10 are the openings 11 in the edge region of the heat transfer element 10 arranged. In this respect, the openings point to the inner wall of the reaction tube 2 a distance smaller than the distance of the opening 2 to a center axis M of the reaction tube. This will be close to the inside of the reaction tube 2 Turbulence formed, which are indicated by an arrow T.

At the bottom of the 2 shown heat transfer element are the openings 11 near the central axis M of the reaction tube 2 arranged.

The heat transfer elements 10 can be arranged within the catalyst bed, not shown for reasons of clarity.

In the 3 is another embodiment of a reaction tube 2 with a heat transfer element 10 shown. The heat transfer element 10 has a cross-shaped cross-section. It extends perpendicular to the longitudinal axis L of the reaction tube from a first inner side of the reaction tube 2 to an opposite, second inside of the reaction tube. In addition, it extends in a direction parallel to the longitudinal axis L of the reaction tube 2 , The catalyst bed is in this reaction tube 2 between the arms of the cross-shaped heat transfer element 10 arranged so that the heat transfer element 10 is arranged in the catalyst bed during operation of the device.

The 4 shows a third embodiment of a reaction tube 2 with a heat transfer element 10 , This heat transfer element has a cross-shaped cross-section, wherein the arms of the cross have a curvature. Also this heat transfer element 10 is arranged in the operation of the device in the catalyst bed.

5 and 6 show a fourth embodiment of a reaction tube 2 with formed as wires heat transfer elements 10 , The heat transfer elements 10 extend in the cross-sectional direction Q of the reaction tube 2 each from an inner side of the reaction tube to the opposite inner side of the reaction tube 2 , The heat transfer elements 10 are on the inside of the reaction tube 2 firmly connected to this, for example, welded. The catalyst bed 3 is in for clarity 6 merely hinted. In operation, the heat transfer elements 10 arranged within the catalyst bed so that they are completely surrounded by this.

In the 7 is another embodiment of a reaction tube 2 with a heat transfer element 10 shown. The heat transfer element 10 is thus in a direction transverse to the longitudinal axis L of the reaction tube 2 arranged that it is from a first inside of the reaction tube 2 to an opposite, second inside of the reaction tube 2 extends. In the area above the heat transfer element 10 is a catalyst bed 3 arranged. Within the catalyst bed is a particulate Wärmeleitmaterial 13 , which has a higher thermal conductivity than the catalyst bed. Furthermore, particulate heat conduction material is above the catalyst bed 13 intended.

The reaction tubes described above 2 for the passage of the hydrocarbon each have at least one heat transfer element 10 which is so in a direction transverse to a longitudinal axis L of the reaction tube 2 is arranged that it is from a first inside of the reaction tube 2 to an opposite, second inside of the reaction tube 2 extends. In a direction perpendicular to the flow direction of the hydrocarbon, therefore, a temperature profile can be achieved, which has lower fluctuations compared to a known reaction tube without heat transfer elements. Further, the conditions for desired reactions in the reaction tube are improved, so that increased productivity can be achieved. The lower temperature gradients can reduce the risk of catalyst breakdown due to thermal stress and increase the life of the catalyst. In addition, it becomes possible to use reaction tubes having a larger diameter than the prior art.

LIST OF REFERENCE NUMBERS

1

 Device for reforming a hydrocarbon

2

 reaction tube

3

 catalyst bed

4

 firing device

5

 burner chamber

6

 Input manifold

7

 Output manifold

10

 Heat transfer element

11

 opening

13

 thermal interface material

M

 central axis

L

 longitudinal axis

Q

 Cross-sectional direction

T

 turbulence

Claims (11)

Device for reforming a hydrocarbon with a reaction tube ( 2 ) for passing the hydrocarbon, one within the Reaction tube ( 2 ), particulate catalyst bed ( 3 ) and one outside the reaction tube ( 2 ) ( 4 ) for heating the reaction tube ( 2 ), Characterized in that (within the reaction tube 2 ) at least one heat transfer element ( 10 ) in a direction transverse to a longitudinal axis (L) of the reaction tube ( 2 ) is arranged so that it is from a first inner side of the reaction tube ( 2 ) to an opposite, second inside of the reaction tube ( 2 ). Apparatus according to claim 1, characterized in that the heat transfer element ( 10 ) is formed as a plate, wherein a main plane of extension of the plate perpendicular to the longitudinal axis (L) of the reaction tube ( 2 ) and wherein the plate has at least one opening ( 11 ) for the passage of the hydrocarbon. Apparatus according to claim 2, characterized in that the opening to the inner wall of the reaction tube ( 2 ) has a distance which is smaller than a distance of the opening ( 11 ) to a central axis (M) of the reaction tube. Apparatus according to claim 1, characterized in that the heat transfer element ( 10 ) is designed as a network. Apparatus according to claim 1, characterized in that the heat transfer element ( 10 ) is formed as a wire. Apparatus according to claim 1, characterized in that the heat transfer element ( 10 ) has a cross-shaped cross-section. Apparatus according to claim 1 or 4 to 6, characterized in that the heat transfer element ( 10 ) in a direction parallel to the longitudinal axis (L) of the reaction tube ( 2 ). Device according to one of the preceding claims, characterized in that the heat transfer element ( 10 ) within the catalyst bed ( 3 ) is arranged. Device according to one of the preceding claims, characterized in that within the catalyst bed ( 3 ) a particulate heat conducting material ( 13 ), wherein the particulate heat-conducting material ( 13 ) a higher thermal conductivity than the catalyst bed ( 3 ) having. Device according to one of the preceding claims, characterized in that in the reaction tube ( 2 ) a plurality of heat transfer elements ( 10 ) are arranged. Process for reforming a hydrocarbon, wherein the hydrocarbon is passed through a reaction tube ( 2 ), within which a particulate catalyst bed ( 3 ), and wherein the reaction tube ( 2 ) through an outside of the reaction tube ( 2 ) ( 4 ) is heated, characterized in that within the reaction tube ( 2 ) at least one heat transfer element ( 10 ) is arranged such that from a first side of the inner wall of the reaction tube ( 2 ) extends to an opposite side of the inner wall.

Images