Abstract
A synthesis device may include a pressure vessel with an inlet and an outlet for fluid, a catalyst bed that is disposed within the pressure vessel, a plate heat exchanger that is disposed in a flow path of fluid between the inlet of the pressure vessel and the catalyst bed such that fluid flowing into the catalyst bed is heated by fluid flowing out of the catalyst bed. The plate heat exchanger may be disposed outside a reactor volume occupied by the catalyst bed in the pressure vessel. The catalyst bed may be one of a plurality of catalyst beds disposed axially over one another in the pressure vessel.
Claims
1.-18. (canceled)
19. A synthesis device for exothermic reactions with heterogeneous catalysis, the synthesis device comprising: a pressure vessel that includes an inlet and an outlet for fluid; a catalyst bed disposed within the pressure vessel, the catalyst bed having a cylinder ring form or hollow cylindrical configuration; and a plate heat exchanger disposed in a flow path of fluid between the inlet of the pressure vessel and the catalyst bed such that fluid flowing into the catalyst bed is heated by fluid flowing out of the catalyst bed, wherein the plate heat exchanger is disposed outside a reactor volume occupied by the catalyst bed in the pressure vessel, wherein the plate heat exchanger is disposed on an inside of the catalyst bed such that the catalyst bed surrounds the plate heat exchanger concentrically.
20. The synthesis device of claim 19 wherein the plate heat exchanger is one of a plurality of heat exchangers.
21. The synthesis device of claim 19 wherein the plate heat exchanger is a first plate heat exchanger, wherein a second plate heat exchanger is disposed below the catalyst bed.
22. The synthesis device of claim 19 wherein the plate heat exchanger is a first plate heat exchanger, wherein a second plate heat exchanger is disposed in a region between the catalyst bed and an inner wall of the pressure vessel.
23. The synthesis device of claim 19 wherein the catalyst bed is one of a plurality of catalyst beds disposed axially over one another in the pressure vessel.
24. The synthesis device of claim 19 wherein the plate heat exchanger comprises a plurality of plates with a flow-traversible interspace between adjacent pairs of the plurality of plates, with the flow-traversible interspaces of a first group being in fluid communication with a common first fluid channel running perpendicularly to the plurality of plates and being sealed off from surroundings of the plate heat exchanger, with the flow-traversible interspaces of a second group being in fluid communication with the surroundings and being sealed off from the interspaces of the first group.
25. The synthesis device of claim 24 wherein the interspaces of the first group and the interspaces of the second group are disposed in alternation.
26. The synthesis device of claim 24 wherein each of the plurality of plates has a circular shape.
27. The synthesis device of claim 24 wherein the interspaces of the second group have lateral inflow openings that allow fluid to flow into the interspaces of the second group.
28. The synthesis device of claim 24 wherein the interspaces of the first group are in fluid communication with a plurality of second fluid channels that run perpendicularly to the plurality of plates and are disposed such that fluid flows through the interspaces of the first group, starting from the common first fluid channel, radially to the plurality of second fluid channels, or through the interspaces of the first group, starting from the plurality of second fluid channels, radially to the common first fluid channel.
29. The synthesis device of claim 28 wherein the interspaces of the second group are in fluid communication with a plurality of third fluid channels that run perpendicular to the plurality of plates and are disposed such that fluid flows through the interspaces of the second group, starting from lateral inflow openings of the interspaces of the second group, radially to the plurality of third fluid channels.
30. A method for producing a product, the method comprising: providing a reactant stream comprising reactants, wherein the reactants include at least hydrogen and nitrogen; introducing the reactant stream into a pressure vessel; preheating the reactant stream in a plate heat exchanger that is disposed in a flow path of the reactant stream between an inlet of the pressure vessel and a catalyst bed; conveying the reactant stream that has been preheated onto the catalyst bed; reacting at least a portion of the reactants of the reactant stream on the catalyst bed under an adiabatic regime to form a product stream comprising reactants and product, wherein the product stream comprises ammonia; and introducing the product stream into the plate heat exchanger, the product stream being cooled.
31. The method of claim 30 wherein the catalyst bed is a first catalyst bed, wherein the product stream is a first product stream, the method comprising: introducing the product stream into a second catalyst bed; and reacting at least a portion of the reactants of the first product stream in the second catalyst bed to form a second product stream comprising reactants and product.
32. The method of claim 30 wherein the reaction is an exothermic reaction with heterogeneous catalysis.
33. The method of claim 30 wherein the preheating comprises preheating the reactant stream to a temperature of at least 300 C.
Description
[0070] FIG. 1 shows a plate heat exchanger according to one working example in a sectional representation along a section plane oriented parallel to the plates of the plate heat exchanger.
[0071] FIG. 2a shows the plate heat exchanger according to FIG. 1 in a schematic sectional representation along a section plane oriented perpendicularly to the plates of the plate heat exchanger, in order to illustrate a flow regime according to the countercurrent principle.
[0072] FIG. 2b shows the plate heat exchanger according to FIG. 1 in a schematic sectional representation along a section plane oriented perpendicularly to the plates of the plate heat exchanger, in order to illustrate a flow regime according to the concurrent principle.
[0073] FIG. 3 shows a plurality of synthesis devices having heat exchangers to illustrate different installation scenarios of heat exchangers.
[0074] FIG. 4 shows the flow regime within a synthesis device having a heat exchanger which is disposed on the outside of the catalyst bed.
[0075] FIG. 5 shows the flow regime within a synthesis device having a heat exchanger which is disposed above the catalyst bed.
[0076] FIG. 1 shows a plate heat exchanger 7 according to one working exemplary embodiment of the invention. The plate heat exchanger 7 has a first fluid channel 1, which is disposed centrally along the longitudinal axis of the plate heat exchanger 7 perpendicularly to the individual plates 20 of the plate heat exchanger 7. The first fluid channel 1 has a circular cross section. Moreover, there are second 2 and third 3 fluid channels provided in the plate heat exchanger. The second 2 and third 3 fluid channels run perpendicularly to the plates 20 and are oriented parallel to one another. The second fluid channels 2 are preferably disposed in the region of the outer edge of the plates 20 of the plate heat exchanger 7. The third fluid channels 3 are preferably disposed around the first fluid channel 1. The second fluid channels 2 and the third fluid channels 3 are each arranged on an arc whose center point coincides with a longitudinal axis of the first fluid channel 1. The cross section of the second fluid channels 2 and of the third fluid channels 3 is circular in configuration. In deviation from this, the cross section of the second fluid channels 2 and of the third fluid channels 3 may be oval or V-shape in design.
[0077] The flow conditions within the plate heat exchanger 7 will be explained below with reference to the representations in FIG. 2a and FIG. 2b, with FIG. 2 showing operation of the plate heat exchanger in accordance with the countercurrent principle, and FIG. 3 showing operation in accordance with the concurrent principle. Disposed between the individual plates 20 are flow-traversable interspaces, which for the following consideration are divided into a first group 5 and a second group 6, with adjacent interspaces each belonging to different groups 5, 6. The flow-traversable interspaces of the first group 5 are in fluid communication with the first fluid channel 1 and are sealed off from the surroundings of the plate heat exchanger 7. Accordingly, the flow of a first fluid into and/or out of the interspaces of the first group 5 in a direction parallel to the plates 20 is prevented. The flow-traversable interspaces of the second group 6 are in fluid communication with the surroundings of the plate heat exchanger 7 and are sealed off from the interspaces of the first group 5. In order to allow a second fluid to flow into the interspaces of the second group 6 from an inflow direction disposed parallel to the plates 20, the plate heat exchanger 7 comprises lateral inflow openings 4.
[0078] FIG. 2a outlines the flow regime within the plate heat exchanger 7, the plate heat exchanger 7 being operated in countercurrent. A first fluid in this case flows via the first fluid channel 1 into the plate heat exchanger 7, flows through the interspaces of the first group 5, radially from the first fluid channel 1 to the second fluid channels 2, in other words from inside to outside, and departs the plate heat exchanger 7 via the second fluid channels 2. The interspaces of the first group 5 are in this case connected via the first fluid channel 1 in the manner of a parallel circuit, and so the stream of the first fluid guided in the first fluid channel 1 is divided into a plurality of substreams. A second fluid flows via the lateral inflow openings 4 into the interspaces of the second group 6, flows through these interspaces radially from outside to inside, and departs the plate heat exchanger 7 via the third fluid channels 3. The interspaces of the second group 6 as well are connected via the third fluid channels 3 in the manner of a parallel circuit, and so the second fluid is passed from different interspaces of the second group 6 into the common third fluid channels 3.
[0079] FIG. 2b outlines the flow regime within the plate heat exchanger 7, the plate heat exchanger 7 being operated in concurrent. In concurrent operation, the first fluid here flows via the second fluid channels 2 into the plate heat exchanger 7, flows through the interspaces of the first group 5, radially from the second fluid channels to the first fluid channel 1, in other words from outside to inside, and departs the plate heat exchanger 7 via the first fluid channel 1. The interspaces of the first group 5 here are connected via the first fluid channel 1 in the manner of a parallel circuit. The second fluid flows via the lateral inflow openings 4 into the interspaces of the second group 6, flows through these interspaces radially from outside to inside, and departs the plate heat exchanger 7 via the third fluid channels 3. The interspaces of the second group 6 as well are connected via the third fluid channels 3 in the manner of a parallel circuit.
[0080] FIG. 3 shows possible arrangements of heat exchangers 7, 8 in a synthesis device 13, more particularly an ammonia synthesis converter. The catalyst beds 9 of the synthesis device 13 are preferably of cylinder ring form, i.e., hollow cylindrical configuration. Example A shows a synthesis device 13 having a heat exchanger 8 which is disposed on the outside of the hollow cylindrical catalyst beds 9. Example B shows a synthesis device 13 having a heat exchanger 8 which is disposed on the inside of a hollow cylindrical catalyst bed 9. Example C shows a synthesis device 13 having a heat exchanger 8 which is disposed above a catalyst bed 9. In the case of synthesis devices having three catalyst beds disposed axially over one another, moreover, the possibly exists of disposing a heat exchanger 8 between two catalyst beds 9. In the case of such a design, in view of the high pressure losses, preference is given to providing a parallel circuit of the flow pathways, by means, for example, of a design of the heat exchanger 8 with a multi-way helix. Example D shows a synthesis device 13 having a plate heat exchanger 7 which is disposed above the catalyst bed 9, Example E shows a synthesis device having a plate heat exchanger 7 which is disposed on the inside of the hollow cylindrical catalyst bed 9. Alternatively to this, though not represented in the drawings, it is also possible for a plate heat exchanger to be disposed below a catalyst bed 9.
[0081] FIG. 4 shows by way of example a synthesis device 13 having two catalyst beds 9, 9 lying axially over one another and having a heat exchanger 7, 8 which is configured as a plate heat exchanger. The heat exchanger 7, 8 is disposed on the outside of the catalyst bed 9. The reactant stream 10 flows through an inlet 15 into a splitting compartment between the inside of an insert 17, which is disposed in the pressure vessel, and the outside of the heat exchanger 7, 8, this flow being downward, and it subsequently flows through the heat exchanger 7, 8 from bottom to top, the reactant stream 10 preferably being preheated to about 380 C. The reactant stream 10 thus preheated flows through the first catalyst bed 9 radially from inside to outside. At this point there is preferably an exothermic reaction. The product stream 11 preferably departs the catalyst bed 9 with a temperature of at most 525 C. and is introduced into the heat exchanger 7, 8, the product stream 11 being cooled. The product stream 11 thus cooled is passed into a further catalyst bed 9, through which it flows preferably radially from outside to inside, and a further portion of the reactants contained in the product stream 11 are converted into product. The further product stream 12 thus formed preferably departs the synthesis device 13 through the outlet 16 disposed in the lower region of the pressure vessel 14.
[0082] FIG. 5 shows by way of example a synthesis device 13 having two catalyst beds 9, 9, lying axially over one another, and having a heat exchanger, configured as a plate heat exchanger 7, which is disposed above the catalyst bed 9. The reactant stream 10, introduced into the pressure vessel through the inlet, flows into the heat exchanger 7, 8, is subsequently conveyed via a circumferential surface of the insert 17 between the inside of the pressure vessel 14 and the outside of the first catalyst bed 9, and flows through the first catalyst bed 9 radially from outside to inside. The hot product stream 11 flows along the inside of the first catalyst bed 9 into the heat exchanger 7, 8, where it is cooled. The product stream 11 cooled in this way is passed into a second catalyst bed 9, through which it flows radially from inside to outside. The further product stream 12 thus formed is subsequently passed out of the synthesis device 13 through an outlet 16 which is disposed in the lower region of the pressure vessel 14.
[0083] The above figures show synthesis devices 13, more particularly ammonia synthesis converters, which comprise the following components: [0084] a) a pressure vessel 14 which comprises an inlet 15 and an outlet 16 for a fluid; [0085] b) at least one catalyst bed 9 which is disposed within the pressure vessel 14; [0086] c) at least one heat exchanger 7, 8, the heat exchanger 7, 8 being disposed in the flow path of the fluid between the inlet 15 of the pressure vessel 14 and the catalyst bed 9 in such a way that the fluid flowing into the catalyst bed 9 is heated by the fluid flowing out of the catalyst bed 9.
[0087] The heat exchangers of these synthesis devices 13 are configured as plate heat exchangers 7, 8. The heat exchanger configured as plate heat exchanger 7, 8 has a much higher heat flow density in comparison to tube bundle heat exchangers, and so the economics of the synthesis devices 13 are enhanced.
LIST OF REFERENCE NUMERALS
[0088] 1 First fluid channel
[0089] 2 Second fluid channels
[0090] 3 Third fluid channels
[0091] 4 Lateral inflow openings
[0092] 5 Flow-traversable interspaces of the first group
[0093] 6 Flow-traversable interspaces of the second group
[0094] 7 Plate heat exchanger
[0095] 8 Plate heat exchanger
[0096] 9/9 Catalyst bed
[0097] 10 Reactant stream
[0098] 11 Product stream
[0099] 12 Further product stream
[0100] 13 Synthesis device
[0101] 14 Pressure vessel
[0102] 15 Inlet
[0103] 16 Outlet
[0104] 17 Insert
[0105] 20 Plate
