METHANOL SYNTHESIS REACTOR

Abstract

The invention relates to a methanol synthesis reactor for producing methanol from a synthesis gas mixture. The reactor according to the invention includes a pressure jacket having an interior in which a first and a second process unit are arranged one atop the other. Both process units are fluidically interconnected at least in respect of the process gases and configured as plate heat exchangers, preferably pillow plate heat exchangers. The plate interiors are traversable from bottom to top by cooling media while the plate interspaces are traversable from top to bottom by process gases, in particular synthesis gas and methanol-containing product streams. At least the first of the two process units has a methanol synthesis catalyst on the plate interspace side. The second process unit is used for cooling or further conversion of the product stream obtainable in the first process unit.

Claims

1. A methanol synthesis reactor for producing methanol from a synthesis gas mixture comprising: (a) a pressure jacket having an interior, wherein at least a first process unit and a second process unit fluidically interconnected are arranged one atop the other in the interior; (b) a first process unit, wherein the first process unit is configured as a reactor stage RS1 for synthesis of methanol from a synthesis gas stream over a catalyst bed CB1, thus making it possible to produce a methanol-containing product stream RP1, and the first process unit is in the form of a plate heat exchanger, wherein the first process unit comprises a multiplicity of plates arranged vertically and parallel to one another with traversable plate interiors and plate interspaces are present between adjacent plates, wherein a solid methanol synthesis catalyst forming the catalyst bed CB1 is arranged in the plate interspaces and the first process unit is configured such that the plate interspaces are traversable from top to bottom by the synthesis gas stream and/or by the methanol-containing product stream RP1 and the plate interiors are traversable from bottom to top by a first cooling media stream CM1, thus making the methanol-containing product stream RP1 coolable in countercurrent by the first cooling media stream CM1, and wherein the first process unit comprises means for withdrawing the methanol-containing product stream RP1 from the first process unit; (c) a second process unit arranged below the first process unit, wherein the second process unit is in the form of a plate heat exchanger, wherein the second process unit comprises a multiplicity of plates arranged vertically and parallel to one another with traversable plate interiors, and plate interspaces are present between adjacent plates, wherein the second process unit is configured such that the plate interiors are traversable from bottom to top by a second cooling media stream CM2 and wherein (c1) the second process unit is in the form of a cooling stage and configured such that the plate interspaces are traversable from top to bottom by the methanol-containing product stream RP1, thus making the methanol-containing product stream RP1 coolable in countercurrent by the second cooling media stream CM2 or (c2) the second process unit is in the form of a reactor stage RS2 and configured for synthesis of methanol from the methanol-containing product stream RP1 withdrawable from the first process unit over a catalyst bed CB2, thus configuring the methanol synthesis reactor to produce a methanol-containing product stream RP2, and wherein a solid methanol synthesis catalyst forming the catalyst bed CB2 is arranged in the plate interspaces and the second process unit is configured such that the plate interspaces are traversable from top to bottom by the methanol-containing product stream RP1 and/or the methanol-containing product stream RP2, thus making the methanol-containing product stream RP2 coolable in countercurrent by the second cooling media stream CM2.

2. The methanol synthesis reactor according to claim 1, wherein the plates of the first process unit and/or the plates of the second process unit are in the form of pillow plates.

3. The methanol synthesis reactor according to claim 1, wherein the second process unit is configured such that the plate interiors are traversable by the synthesis gas stream, wherein the synthesis gas stream fulfils the function of the second cooling media stream CM2, thus configuring the methanol synthesis reactor to produce a preheated synthesis gas stream.

4. The methanol synthesis reactor according to claim 3, wherein the methanol synthesis reactor comprises a means for discharging the preheated synthesis gas stream from the second process unit and comprises a means for introducing the preheated synthesis gas stream into the first process unit to produce the methanol-containing product stream RP1.

5. The methanol synthesis reactor according to claim 1, wherein the plate interiors of the first process unit and the plate interiors of the second process unit are arranged at least partially in serial alignment and/or the plate interspaces of the first process unit and the plate interspaces of the second process unit are arranged at least partially in serial alignment.

6. The methanol synthesis reactor according to claim 1, wherein the methanol synthesis reactor comprises a support structure, wherein the support structure is in the form of a propping means which is at least partially arranged below a process unit and/or in the form of a suspending means arranged at least partially above a process unit and thus forms a mechanical connection between a process unit and the pressure jacket.

7. The methanol synthesis reactor according to claim 6, wherein the first process unit has a support structure which is arranged at least partially below the first process unit and is in the form of a propping means and the second process unit has a support structure which is arranged at least partially above the second process unit and is in the form of a suspending means.

8. The methanol synthesis reactor according to claim 6, wherein the first process unit has a support structure which is arranged at least partially above the first process unit and is in the form of a suspending means and wherein the first and the second process unit are mechanically connected to one another via a connecting element.

9. The methanol synthesis reactor according to claim 3, further comprising a synthesis gas inlet port extending through the pressure jacket, wherein the synthesis gas inlet port is fluidically connected to the plate interiors of the second process unit and is configured for introducing the synthesis gas stream into the second process unit.

10. The methanol synthesis reactor according to claim 9, wherein the second process unit comprises in the bottom region a distributor system which is fluidically connected to the synthesis gas inlet port and the plate interiors of the second process unit and is configured for distributing the synthesis gas stream entering via the synthesis gas inlet port to the plate interiors of the second process unit.

11. The methanol synthesis reactor according to claim 3, wherein the second process unit comprises in the top region a collector system which is fluidically connected to the plate interiors of the second process unit and is configured for collecting the preheated synthesis gas stream exiting from the plate interiors of the second process unit.

12. The methanol synthesis reactor according to claim 11, wherein the first process unit comprises in the top region a distributor system which is fluidically connected to the collector system of the second process unit and configured for distributing the preheated synthesis gas to the plate interspaces of the first process unit.

13. The methanol synthesis reactor according to claim 12, wherein the collector system of the second process unit and the distributor system of the first process unit are connected via a conduit bypassing the first process unit and at least partially running inside the pressure jacket.

14. The methanol synthesis reactor according to claim 1, wherein the first cooling media stream CM1 comprises boiling boiler feed water and the first cooling media stream CM1 is especially evaporable upon traversal of the plate interiors of the first process unit.

15. The methanol synthesis reactor according to claim 1, wherein an interspace region is arranged within the pressure jacket between the first process unit and the second process unit, wherein the interspace region is fluidically connected to the plate interspaces of the first process unit and the plate interspaces of the second process unit) and is configured for transferring the methanol-containing product stream RP1 from the first process unit into the second process unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] The invention is hereinbelow more particularly elucidated by exemplary embodiments. In the following detailed description reference is made to the accompanying figures which form a part of the exemplary embodiments and which contain an illustrative representation of specific embodiments of the invention. In this connection, direction-specific terminology such as top, bottom, front, back, etc., is used with reference to the orientation of the described figure. Since components of embodiments may be positioned in a multiplicity of orientations, the direction-specific terminology is used for elucidation and is in no way limiting. A person skilled in the art will appreciate that other embodiments may be used and structural or logical changes may be undertaken without departing from the scope of protection of the invention. The following detailed description is therefore not to be understood in a limiting sense, and the scope of protection of the embodiments is defined by the accompanying claims. Unless otherwise stated, the drawings are not true to scale.

[0141] In the following description and in the drawings identical elements are described with identical reference numerals. Arrows illustrate the flow direction of the process media, i.e. of the synthesis gas stream and the methanol-containing product streams RP1 and RP2 and the cooling media CM1 and CM2.

[0142] In the figures:

[0143] FIG. 1 shows a much simplified schematic representation of a methanol synthesis reactor as per alternative c1 according to a first example of the invention,

[0144] FIG. 2 shows a much simplified schematic representation of a methanol synthesis reactor as per alternative c1 according to a second example of the invention,

[0145] FIG. 3 shows a much simplified schematic representation of a methanol synthesis reactor as per alternative c2 according to a third example of the invention,

[0146] FIG. 4 shows a much simplified schematic representation of a methanol synthesis reactor as per alternative c2 according to a first example of the invention,

[0147] FIG. 5 shows a typical temperature profile of a catalyst bed over the length of a methanol reactor as determined by measurement and by means of a simulation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0148] FIG. 1 shows a highly simplified schematic representation (outline sketch) of a methanol synthesis reactor 1 according to a first example of the invention. According to alternative c1 the methanol synthesis reactor 1 has a first process unit 13 which is in the form of a reactor stage RS1. Furthermore and according to alternative c1 the methanol synthesis reactor 1 has a second process unit 14a which is configured as a cooling stage.

[0149] The methanol synthesis reactor 1 is shown in a front view on the left-hand side of FIG. 1. FIG. 1 further shows a side view of a portion of the first process unit 13 at the top right and a side view of a portion of the second process unit 14a at the bottom right.

[0150] The methanol synthesis reactor 1 according to FIG. 1 shows a pressure jacket 11 in whose interior 12 a first process unit 13 and a second process unit 14a are arranged. The first process unit 13 is arranged in an upper portion of the interior 12 while the second process unit 14a is arranged in a lower portion of the interior 12 and below the first process unit 13. Both process units 13 and 14a are fluidically interconnected, for example via corresponding pipe conduits of distributor and collector systems (not shown).

[0151] The methanol synthesis reactor 1 is in the form of a one-stage reactor having a reactor stage RS1 and a cooling stage. The reactor stage RS1 is formed by the first process unit 13 and the cooling stage by the second process unit 14a. Boiling boiler feed water is used as the cooling media stream CM1 in the first reactor stage. The cooling media stream CM2 used in the cooling stage is the synthesis gas stream which is also used in the reactor stage RS1 for converting into methanol over a catalyst bed CB1. The synthesis gas stream is preheated in the second process unit 14a and may subsequently be introduced as preheated synthesis gas stream into the first process unit 13 for conversion into methanol.

[0152] The first process unit 13 is in the form of a plate heat exchanger, wherein the plate heat exchanger comprises a multiplicity of traversable (heat exchanger) plates which are in the form of pillow plates (pillow plate structure not shown). The plates are arranged vertically and are accordingly traversed in the vertical direction. The plates 15 each have a traversable plate interior 16 which is traversed from bottom to top by the cooling media stream CM1 33. The stream of the fresh cooling medium CM1 33 enters a plate 15 from below and exits from the top of the relevant plate 15 as a stream of exhausted cooling medium CM1 34. The fresh cooling media stream CM1 33 is boiling boiler feed water. The exhausted cooling media stream CM1 34 is steam. Two adjacent plates 15 of the first process unit 13 are spaced apart from one another such that they form a plate interspace 17. Pellets of a methanol synthesis catalyst, indicated by the black dots, are arranged in the plate interspaces 17. The entirety of the catalyst pellets form the catalyst bed CB1 18a. A preheated synthesis gas stream 29 enters the plate interspaces 17 from above and is at least partially converted into a mixture of methanol and water (raw methanol) in an exothermic reaction over the catalyst bed CB1 18a. The plate interspaces are cooled, and the temperature in the plate interspaces thus controlled, by the cooling media stream CM1 33 in countercurrent. In the context of this exothermic reaction a product stream RP1 comprising at least methanol, water and unconverted synthesis gas (residual gas) is formed. This product stream RP1 30 exits from the bottom of the plate interspaces 17.

[0153] The second process unit 14a is also in the form of a plate heat exchanger, wherein the plate heat exchanger comprises a multiplicity of traversable (heat exchanger) plates 15 which are in the form of pillow plates (pillow plate structure not shown). The plates are arranged vertically and are accordingly traversed in the vertical direction. The plates 15 of the second process unit each have a traversable plate interior 16 which is traversed from bottom to top by the cooling media stream CM2 28. The stream of the fresh cooling medium CM2 28 enters the plate 15 from below and exits from the top of the plate 15 as a stream of exhausted cooling medium CM2 29. The fresh cooling media stream CM2 28 is the synthesis gas stream. The exhausted cooling media stream CM2 29 is the preheated synthesis gas stream.

[0154] Two adjacent plates 15 of the second process unit 14a are spaced apart from one another such that they form a plate interspace 17. In contrast to the plate interspaces of the first process unit 13, the plate interspaces 17 of the second process unit do not have a methanol synthesis catalyst arranged in them since the second process unit is used only for cooling and optionally condensing the methanol-containing product stream RP1 30. The plate interspaces 17 traversed from top to bottom by the methanol-containing product stream RP1 30 are cooled by the cooling media stream CM2 28 in countercurrent, thus cooling the initially hot methanol-containing product stream RP1 30 to afford the cold methanol-containing product stream RP1 31. Depending on the configuration of the second process unit 14a the methanol-containing product stream RP1 31 may be obtained in merely cooled but still gaseous form, in partially condensed form or in completely condensed form with respect to the condensable proportions.

[0155] As is shown on the right hand side of FIG. 1, the traversable plates 15 with their plate interiors 16 and the plate interspaces 17 of the first and second process unit 13 and 14a are each arranged in serial alignment with one another. In other words, the plates and plate interspaces of the first and second process unit 13 and 14a are each arranged in series along a common longitudinal axis.

[0156] The first process unit 13 of the methanol synthesis reactor 1 is mechanically connected to the pressure jacket 11 via a support structure 19, the support structure 19 thus establishing a mechanical connection between the first process unit and the pressure jacket 11 (connection to pressure jacket in plane of the drawing). The support structure 19 is in the form of a propping means and at least partially arranged below the first process unit 13. In contrast to an arrangement at the side of the first process unit 13 this arrangement has the advantage that the diameter of the methanol synthesis reactor 1 is not significantly affected, in particular not significantly increased. The configuration of the support structure 19 as a propping means allows the first process unit to expand freely upwards. This especially refers to the packet of the heat exchanger plates and components mechanically connected thereto. Components mechanically connected to the heat exchanger plates are in particular the collector and distributor systems 24, 25 and 26.

[0157] The second process unit 14a of the methanol synthesis reactor 1 is mechanically connected to the pressure jacket 11 via a support structure 20, the support structure 20 thus establishing a mechanical connection between the second process unit and the pressure jacket 11 (connection to pressure jacket in plane of the drawing). The support structure 20 is in the form of a suspending means and at least partially arranged above the first process unit 14a. In contrast to an arrangement at the side of the second process unit 14a this arrangement has the advantage that the diameter of the methanol synthesis reactor 1 is not significantly affected, in particular not significantly increased. The configuration of the support structure 20 as a suspending means allows the second process unit 14a to expand freely downwards. This especially refers to the packet of the heat exchanger plates and components mechanically connected thereto. Components mechanically connected to the heat exchanger plates are in particular the collector and distributor systems 22, 23 and 27.

[0158] The flow management in the inventive reactor 1 is elucidated hereinbelow. The synthesis gas stream 28 enters the methanol synthesis reactor 1 via a synthesis gas inlet port (not shown) which extends through the pressure jacket 11 in the horizontal direction. The synthesis gas stream 28 is subsequently distributed via a distributor system 22 (shown in simplified form and for simplicity as part of a block with the components 22, 27) to the individual plate interiors 16 of the first process unit. The synthesis gas subsequently flows from bottom to top through the plate interiors 16, thus cooling the product stream RP1 30 on the side of the plate interspaces 17 in countercurrent. The synthesis gas stream 28 fulfils the function of the cooling media stream CM2. The preheated synthesis gas stream 29 or exhausted cooling media stream CM2 is combined in a collector system 23 and passed to the top of the first process unit via a bypass conduit (indicated by the dashed line). The preheated synthesis gas stream 29 there enters a distributor system 24 (shown in simplified form and for simplicity as part of a block with the components 24, 26) which distributes the synthesis gas over the plate interspaces 17 of the first process unit. In the plate interspaces 17 of the first process unit the preheated synthesis gas reacts over the methanol synthesis catalyst of the catalyst bed to afford methanol and water and thus forms the product stream RP1 30 which also comprises unconverted synthesis gas (residual gas). The product stream RP1 30 flows from top to bottom and is withdrawn from the first process unit 13 in the bottom region thereof, flows through an interspace region (not shown) and subsequently enters the plate interspaces 17 of the second process unit 14a for cooling. The cooled product stream RP1 31 is combined using a collector system 27 (shown in simplified form and for simplicity as part of a block with the components 22, 27) and discharged from the reactor via a product stream outlet port (not shown). The thus-obtainable raw product is subsequently sent to a further treatment (for example further cooling and gas-liquid separation) and workup (for example distillation).

[0159] The interspace region between the first and the second process unit may likewise exhibit a corresponding collector system for the product stream RP1 in the bottom region of the first process unit 13 and a corresponding distributor system for the product stream RP1 at the top region of the second process unit 14a.

[0160] The fresh cooling media stream CM1 33 enters the reactor via a horizontally arranged cooling media inlet port (not shown) which extends through the pressure jacket 11 and is distributed to the plate interiors 16 of the first process unit 13 via a distributor system 25. This causes the boiling boiler feed water used for the cooling media stream CM1 33 to evaporate, thus effecting a cooling of the product stream RP1 formed on the plate interspaces. The steam or exhausted cooling media stream CM1 34 is combined in a collector system 26 (shown in simplified form and for simplicity as part of a block with the components 24, 26) and discharged from the reactor 1 via a horizontally arranged cooling media outlet port which extends through the pressure jacket.

[0161] The examples according to FIGS. 2 to 4 will not be elucidated in detail again below. Only differences with respect to the example of FIG. 1 will be addressed.

[0162] FIG. 2 shows a highly simplified schematic representation (outline sketch) of a methanol synthesis reactor 2 according to a second example of the invention. According to alternative c1 the methanol synthesis reactor 2 also has a first process unit 13 which is in the form of a reactor stage RS1. Furthermore and according to alternative c1 the methanol synthesis reactor 2 has a second process unit 14a which is configured as a cooling stage.

[0163] The methanol synthesis reactor 2 of FIG. 2 differs decisively from the methanol synthesis reactor 1 of FIG. 1 in terms of the type of mechanical fixing of the first and second process units 13 and 14a. Otherwise the methanol synthesis reactor 2 is also configured as a single-stage reactor having a first process unit 13 in the form of a water-cooled reactor stage RS1 and a second process unit 14a in the form of a gas-cooled cooling stage 14a.

[0164] The methanol synthesis reactor 2 according to the example of FIG. 2 has only one mechanical support structure 20 which mechanically connects the first process unit 13 to the pressure jacket 11. The support structure 20 thus establishes a mechanical connection between the first process unit 13 and the pressure jacket 11 (connection to the pressure jacket in plane of the drawing). This support structure 20 is in the form of a suspending means and at least partially arranged above the first process unit 13. In contrast to an arrangement at the side of the first process unit 13, and as already mentioned in connection with the example of FIG. 1, this arrangement has the advantage that the diameter of the methanol synthesis reactor 2 is not significantly affected, in particular not significantly increased.

[0165] In contrast to the example of FIG. 1 the second process unit 14a is not mechanically connected to the pressure jacket 11 via a support structure. On the contrary, the first process unit 13 and the second process unit 14a are mechanically connected to one another via a connecting element 21. However, the connecting element 21 does not establish a mechanical connection to the pressure jacket 11. As a result the first process unit 13 and the second process unit 14a can freely expand downwards. Especially in the case of large steam amounts in respect of the cooling media stream CM1 34 this embodiment has the advantage that the feed conduit of the cooling media stream CM1 33 may be made mechanically more flexible in contrast to the embodiment of FIG. 1.

[0166] FIG. 3 shows a highly simplified schematic representation (outline sketch) of a methanol synthesis reactor 3 according to a third example of the invention. According to alternative c2 the methanol synthesis reactor 3 has a first process unit 13 which is in the form of a reactor stage RS1. Furthermore and according to alternative c2 the methanol synthesis reactor 3 has a second process unit 14b which is configured as a further or second reactor stage RS2.

[0167] In contrast to the examples of the methanol synthesis reactor according to FIGS. 1 and 2 the methanol-containing product stream RP1 30 exiting the first process unit 13 is not only cooled in the second process unit 14b but rather also converted into a methanol-containing product stream RP2 32. This is made possible because the methanol-containing product stream RP1 30 comprises unconverted synthesis gas (carbon oxide(s) and hydrogen) due to the establishment of a thermodynamic equilibrium. This unconverted synthesis gas or residual gas is further converted into methanol and water on the plate interspace side, i.e. within the plate interspaces 17 of the second process unit 14b over the catalyst bed CB2 18b arranged therein. The cooling of this exothermic reaction is carried out via the synthesis gas stream 28 or fresh cooling media stream CM2 28 introduced in the bottom region of the second process unit. Accordingly the methanol synthesis reactor 3 is in the form of a two-stage reactor, wherein the first reactor stage (process unit 13) is configured as a water-cooled reactor stage RS1 with boiling boiler feed water as cooling media stream CM1 33 and the second reactor stage RS2 is configured as a gas-cooled reactor stage with synthesis gas as cooling media stream CM2 28.

[0168] The mechanical fixing of the first and second process unit 13 and 14b to the pressure jacket 11 via the support structures 19 and 20 corresponds to the mechanical fixing as shown and described for the example of the methanol synthesis reactor 1 in FIG. 1.

[0169] FIG. 4 shows a highly simplified schematic representation (outline sketch) of a methanol synthesis reactor 4 according to a fourth example of the invention. According to alternative c2 the methanol synthesis reactor 4 has a first process unit 13 which is in the form of a reactor stage RS1. Furthermore and according to alternative c2 the methanol synthesis reactor 4 has a second process unit 14b which is configured as a further or second reactor stage RS2. As in the example of the reactor according to FIG. 3, the methanol synthesis reactor 4 is also in the form of a two-stage reactor, wherein the first reactor stage RS1 is configured as a water-cooled reactor stage and the second reactor stage RS2 is configured as a gas-cooled reactor stage.

[0170] The mechanical fixing of the first and second process unit 13 and 14b to the pressure jacket 11 via the support structure 20 and the connection of the first and second process unit 13 and 14b via the connecting element 21 corresponds to the configuration as shown and described for the example of the methanol synthesis reactor 2 in FIG. 2.

LIST OF REFERENCE SYMBOLS

[0171] 1, 2, 3, 4 Methanol synthesis reactor [0172] 11 Pressure jacket [0173] 12 Interior [0174] 13 First process unit (reactor stage RS1) [0175] 14a Second process unit (cooling stage) [0176] 14b Second process unit (reactor stage RS2) [0177] (Heat exchanger) plate [0178] 16 Plate interior [0179] 17 Plate interspace [0180] 18a Catalyst bed CB1 [0181] 18b Catalyst bed CB2 [0182] 19 Propping means (support structure) [0183] 20 Suspending means (support structure) [0184] 21 Connecting element [0185] 22 Distributor system (for synthesis gas stream) [0186] 23 Collector system (for preheated synthesis gas stream) [0187] 24 Distributor system (for preheated synthesis gas stream) [0188] 25 Distributor system (for cooling medium) [0189] 26 Collector system (for cooling medium) [0190] 27 Collector system for product stream RP1 or RP2) [0191] 28 Synthesis gas stream (cooling media stream CM2, fresh) [0192] 29 Preheated synthesis gas stream (cooling media stream CM2, exhausted) [0193] 30 Product stream RP1 [0194] 31 Cooled product stream RP1 [0195] 32 Product stream RP2 [0196] 33 Cooling media stream CM1, fresh [0197] 34 Cooling media stream CM1, exhausted

[0198] It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.