Process and plant for production of a process product

Abstract

A process and a plant (100) for production of a process product (15) are proposed, with which it is possible to feed a first reactant stream (11) and a second reactant stream (12) to a reactor (130) and to convert them in the reactor (130) in an exothermic reaction to a crude product (13) containing the process product (15), wherein a chiller system (160, 170) is used to cool (140) the crude product (13) with at least partial condensation or to store (150) the process product (15) that has been formed using at least a portion of the condensed crude product (14) at temperatures below 0°C. A characteristic feature here is that the first (11) and / or second (12) reactant stream is subjected to preliminary cooling (210, 120) using the chiller system (170).

Description

[0001] Description

[0002] Process and plant for the production of a process product

[0003] The invention relates to a process and a plant for producing a process product, in particular ammonia.

[0004] background

[0005] In the typical production of ammonia, elemental nitrogen and elemental hydrogen are reacted with each other. Gaseous ammonia is first obtained, which is then processed into an at least partially liquefied process product using product cooling.

[0006] Depending on the production method used for the two reactants, hydrogen and nitrogen, cooling is required during their preparation. Such cooling systems are typically designed specifically for the respective application, particularly with regard to the heat flows to be absorbed and / or the desired temperature levels.

[0007] Even if the proposed measures are described below in particular with reference to the application example of a production of ammonia, the invention itself, as also explained below, is not limited to the production of ammonia and can also be used beneficially in the context of the production of another process product.

[0008] There is still a need for improvements in corresponding processes, particularly, but not exclusively, with regard to energy efficiency and simplifications in construction implementation.

[0009] overview

[0010] Against this background, a method and a system with the features of the independent claims are proposed, which define the scope of the present invention. Advantageous developments and further embodiments are the subject of the dependent claims and the following description.

[0011] The proposed process makes use of an integration with regard to the application of cooling power in that a refrigerant which is already used for cooling the product of a chemical reaction of a first reactant stream with a second reactant stream or a refrigerant which is used for storing the product at temperatures below 0°C is also used for a pre-cooling carried out in the context of providing at least one reactant stream of the process.

[0012] In detail, a process for producing a process product is proposed, in which a first reactant stream and a second reactant stream are fed to a reactor and are converted in the reactor in an exothermic reaction to form a crude product containing the process product, wherein the crude product is subjected to cooling against a refrigerant with at least partial condensation and the process product is formed using the at least partially condensed crude product and optionally stored using a refrigerant at a temperature of less than 0°C.

[0013] It is proposed that the second reactant stream is subjected to pre-cooling, either alone or in parallel with the first reactant stream, against the refrigerant used for cooling the raw product and / or against the refrigerant used for storing the process product.

[0014] By integrating multiple refrigerant consumers, investment costs can be reduced because a single refrigerant system can be used for multiple purposes, thus eliminating the need for entire system components. On the other hand, the typically very low temperature level of corresponding product cooling increases the purity of the preliminary stage of the respective reactant stream and / or enhances the efficiency of the process used to provide the respective reactant stream. This can contribute to further cost reductions by allowing a purification unit downstream of the pre-cooling to be smaller and operated with lower energy consumption. In at least one embodiment, the first reactant stream contains hydrogen. This is a particularly frequently used reactant stream that is becoming increasingly important, particularly in the context of the decarbonization of the global economy.In particular, the hydrogen can be produced at least partially by electrolysis of water and / or at least partially from a hydrocarbon-containing feedstock and / or at least partially from a feedstock containing elemental hydrogen. These are particularly relevant hydrogen sources that can be used in the context of the transition to an economy based on renewable energy sources. The hydrogen obtained from these sources may contain water.

[0015] The hydrogen can be purified of any water it contains, particularly upstream of the reactor, using adsorption, in particular pressure swing adsorption and / or temperature swing adsorption and / or vacuum pressure swing adsorption and / or a membrane process. The pre-cooling according to the invention can be used particularly advantageously upstream of these purification processes to condense out water, thus reducing the load on the purification processes.

[0016] In at least one embodiment, the second reactant stream contains nitrogen, in particular nitrogen produced at least partially by distillative (cryogenic) separation from ambient air. Nitrogen is one of the most important elements used in the chemical industry and occurs in the ambient air to a high extent in elemental form. Other nitrogen deposits are typically much less available or not sufficiently renewable, so that nitrogen obtained from ambient air is typically used for both sustainability and cost reasons. In the context of the provision of nitrogen, the described cold integration can be used in particular to condense water from the ambient air upstream of the nitrogen separation.

[0017] According to at least one embodiment proposed here, the process product comprises ammonia. This is one of the most important chemical compounds produced on a large industrial scale and the starting material for a multitude of other chemical reactions. In at least one embodiment, the refrigerant is formed at least partially using the process product. This is particularly advantageous because it eliminates cross-contamination between the product and the refrigerant. Thus, an open refrigerant circuit can be used. In other embodiments, however, the use of closed refrigerant circuits is also possible.

[0018] The plant according to the invention for producing a process product comprises a reactor, a cooling device, and a pre-cooling unit, and is configured to carry out a process as described above in one of the proposed embodiments. Thus, the plant benefits from the advantages already described with regard to the embodiments of the process according to the invention in a corresponding manner.

[0019] Further embodiments and advantages of the invention are explained in more detail below with reference to an embodiment shown in Figure 1.

[0020] Figure 1 schematically illustrates an embodiment of the invention in the form of a simplified block diagram, designated overall by 100. The block diagram can be interpreted both as a flowchart of an embodiment of a method according to the invention and as a functional diagram of an embodiment of a system according to the invention.

[0021] Designs

[0022] The embodiments described below are described solely for the purpose of assisting the reader in understanding the claimed and previously discussed features. They are merely examples and are not intended to be exhaustive and / or limiting with regard to the features of the invention. It is to be understood that the advantages, embodiments, examples, functions, features, structures, and / or other aspects described above and below are not to be considered limitations on the scope of the invention, as defined in the claims, as mentioned above, or limitations on equivalents to the claims, and that other embodiments may be used and changes may be made without departing from the scope of the claimed invention.

[0023] Explanations relating to devices, apparatus, arrangements, systems, etc. according to embodiments of the present invention may also apply to methods, processes, methods, etc. according to the embodiments of the present invention, and vice versa. Elements, method steps, etc. that are identical, have the same effect, are functionally equivalent, are structurally identical, or are comparable may be identified by identical reference numerals.

[0024] Processes for producing hydrogen that can be used in connection with the present invention are widely described in the literature. Among many others, reference is made in this context to the article by AO Oni et al., "Comparative assessment of blue hydrogen from steam methane reforming, autothermal reforming, and natural gas decomposition technologies for natural gas-producing regions," Energy Conversion and Management 254 (2022) 115245, which shows such processes in Figures 2 to 4 and describes them in the corresponding text passages.

[0025] The production of hydrogen by water electrolysis is also well known and is described, for example, in the article “Hydrogen” in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, June 15, 2000, DOI: 10.1002 / 14356007.a13_297, particularly in Section 4.2, “Electrolysis”.

[0026] In conventional water electrolysis, an aqueous alkaline solution, typically potassium hydroxide, is used as the electrolyte (AEL, alkaline electrolysis). Electrolysis with a unipolar or bipolar electrode arrangement takes place at atmospheric pressure, or on an industrial scale, significantly higher. Recent developments in water electrolysis include the use of proton-conducting ion exchange membranes (SPE, Solid Polymer Electrolysis; PEM, Proton Exchange Membranes), in which the water to be electrolyzed is provided on the anode side. Electrolysis using anion exchange membranes (AEM, Anion Exchange Membrane) is also known. The water electrolysis processes mentioned so far are low-temperature processes in which the water to be electrolyzed is in the liquid phase.In addition, so-called steam electrolysis is also used, which can also be carried out with alkaline electrolytes (i.e., AEL) with adapted membranes, such as polysulfone membranes, or using solid oxide electrolysis cells (SOECs). The latter particularly include doped zirconium dioxide or oxides of other rare earth elements, which become more conductive at high temperatures.

[0027] The term "electrolysis" will be used below to encompass all of these processes. Low-temperature electrolysis (PEM, AEL, AEM) is particularly suitable for flexible operation, supporting the energy transition to renewable energies.

[0028] All methods can be used in the procedures and corresponding designs proposed here.

[0029] Ammonia production has also been described previously, for example, in M. Appl, "Ammonia: Principles and Industrial Practice," Wiley-VCH, 1999. Variants of the Haber-Bosch process are typically used. The ammonia produced is typically stored at atmospheric pressure and a temperature of -33°C. To generate the ammonia as a liquid product under these conditions, a refrigeration system is typically used for condensation and purification of the ammonia, as discussed previously and explained below.

[0030] As mentioned, closed and / or open refrigerant circuits can be used in the embodiments proposed here. An open refrigerant circuit is characterized in that a portion of a process product, for example ammonia formed in ammonia synthesis, is separated, expanded, thereby evaporated, and used as a refrigerant, and that the corresponding process product, for example the ammonia, is then converted into a product. A refrigerant in a closed refrigerant circuit has no material contact with the process gas, e.g. the gas mixture from ammonia synthesis that is to be cooled. The invention is explained using the example of a plant for producing ammonia as the process product, although embodiments of the invention are also provided by which a different process product is produced.The description of a process for producing ammonia is therefore to be understood purely as an example and does not limit the invention to a narrower field of application than that defined by the patent claims.

[0031] The plant 100 comprises a reactor 130, to which hydrogen is fed as the first reactant stream 11 and nitrogen as the second reactant stream 12, and which is configured to at least partially react the first reactant stream 11 and the second reactant stream 12 with one another in an exothermic reaction to form an ammonia-containing crude product 13. Hydrogen 11 and nitrogen 12 can also (deviating from the illustration in Figure 1) be mixed with one another upstream of the reactor 130 and fed into the reactor 130 as a common feed stream.

[0032] Downstream of reactor 130, the crude product 13 is subjected to cooling 140, wherein at least a portion of the ammonia contained in the crude product 13 is condensed. For this purpose, a liquid refrigerant 141 is used, which can be formed, in particular, from the produced ammonia. The refrigerant 141 is partially or completely evaporated upon heat absorption, producing an evaporated refrigerant 142, which is reliquefied in the refrigeration system 170 by means of a refrigerant compressor and a heat exchanger (not shown in Figure 1) against an external coolant at elevated pressure and temperature.

[0033] Downstream of the product cooling system 140, liquid ammonia 14 is discharged as process product 15 after intermediate storage in the product storage system 150. In order to store the ammonia without pressure, the product storage system 150 is connected to another refrigeration system 160, which keeps the stored ammonia at a temperature of -33°C. Evaporated ammonia 151 serves as the refrigerant, which, after reliquefaction in the refrigeration system 160, is returned to the product storage system 150 as return stream 152. In embodiments of the invention, the refrigerant 141, 142 of the product cooling system 140 can also be used for this reliquefaction. Alternatively, the reliquefaction system 160 can be integrated directly into the product liquefaction system 140. For this purpose, for example, the ammonia vapor 151 upstream of the product liquefaction can be recycled into the raw product 13 in an intermediate step of the product cooling 140 (not shown separately in Figure 1).Conversely, in alternative embodiments of the invention, the refrigerant used for the reliquefaction 160 can also be used as the refrigerant 141, 142 for the product cooling 140.

[0034] The hydrogen 11 is formed from water 1 in an electrolysis 110 upstream of the reactor 130, producing a water-containing hydrogen stream 20 that is processed in the adsorptive H2 dryer 220 to form the anhydrous first reactant stream 11. To relieve the load on the H2 dryer 220, it is preceded by the hydrogen precooler 210, in which the water-containing hydrogen stream 20 is cooled to a temperature of approximately 5°C against cooling water and another coolant 143 in order to condense out water and obtain a pre-dried hydrogen stream 21, which is further treated in the adsorptive H2 dryer (220). The ammonia supplied from the refrigeration system 170 as coolant 143 evaporates against the hydrogen 20 to be cooled and flows back to the refrigeration system 170 as vaporous ammonia 144.

[0035] The nitrogen 12 is separated from ambient air 2 using an air separation plant 260, which is preceded by an adsorptive air dryer 250 and an air pre-cooler 120. In the air pre-cooler 120, the ambient air 2 is cooled to a temperature of approximately 5°C against cooling water (not shown) and another refrigerant 143 in order to condense out water in particular, but also hydrocarbons, and to obtain a pretreated air stream 30, which is processed in the adsorptive air dryer for use in the preferably cryogenically operated air separation plant 260. Nitrogen not required for the second reactant stream 12, as well as other air components such as oxygen and argon, can be discharged as further products of the process 100, although this is not shown separately in Figure 1.

[0036] The multiple use of the refrigeration system 170 according to the invention represents a cost-effective possibility of achieving low temperatures in the pre-cooling systems 210 and 120, due to which the adsorptive gas dryers 220 and 250 have to separate less water and hydrocarbons than in the prior art, so that they can be operated more economically and designed smaller.

Claims

Patent claims 1. A process (100) for producing a process product (15), in which a first reactant stream (11) and a second reactant stream (12) are fed to a reactor (130) and reacted in the reactor (130) in an exothermic reaction to form a crude product (13) containing the process product (15), wherein a refrigeration system (160, 170) is used to cool (140) the crude product (13) with at least partial condensation or to store (150) the process product (15) formed using at least part of the condensed crude product (14) at temperatures below 0°C, characterized in that the second (12) reactant stream is subjected to precooling (210, 120) alone or in parallel with the first reactant stream (11) using the refrigeration system (170).

2. The process (100) according to claim 1, wherein the first reactant stream (11) contains hydrogen.

3. The method according to claim 2, wherein the hydrogen is produced at least partially by means of electrolysis (110) of water (1) and / or at least partially from a hydrocarbon-containing starting material (1) and / or at least partially from a feed (1) containing elemental hydrogen.

4. The method (100) according to claim 2 or 3, wherein the hydrogen (21) is purified (220) upstream of the reactor (130) using adsorption, in particular pressure swing adsorption and / or temperature swing adsorption and / or vacuum pressure swing adsorption, and / or using a membrane process.

5. The method (100) according to claim 4, characterized in that the pre-cooling (210) is carried out upstream of the hydrogen purification (220) in order to condense water.

6. The process according to any one of the preceding claims, wherein the second reactant stream (12) contains nitrogen, in particular nitrogen produced at least partially by distillative separation (260) from ambient air (2).

7. The method according to claim 6, characterized in that the pre-cooling (120) is carried out upstream of the air separation (260) in order to condense water contained in the ambient air (2).

8. The process (100) according to any one of the preceding claims, wherein the process product (15) comprises ammonia.

9. The process (100) according to any one of the preceding claims, wherein a portion of the process product (15) is used as refrigerant (141, 142, 143, 144, 145, 146, 151, 152) in the refrigeration system (160, 170).

10. Plant (100) for producing a process product, comprising a reactor (130), a refrigeration plant (160, 170) and a pre-cooling plant (120, 210), wherein the plant (100) is designed to feed a first reactant stream (11) and a second reactant stream (12) to a reactor (130) and to convert them in the reactor (130) in an exothermic reaction to form a crude product (13) containing the process product (15), wherein a refrigeration plant (160, 170) is used to cool the crude product (13) with at least partial condensation (140) or to store the process product (15) formed using at least part of the condensed crude product (14) at temperatures below 0°C (150), characterized in that it is further designed to cool the second reactant stream (12) alone or in parallel with the first reactant stream (11) using the Refrigeration system (170) to be subjected to pre-cooling (210, 120).

11. Plant according to claim 10, which is arranged to carry out a method according to one of claims 1 to 7.

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