Arrangement for compressing a synthesis gas, and method for operating the arrangement

Abstract

The invention relates to a method for operating an arrangement (1) for compressing synthesis gas, wherein, in a first step, the synthesis gas is compressed in a first compressor unit (4) from an initial pressure to a first preliminary pressure, wherein, in a second step, the synthesis gas flows into a second compressor unit (10) and is compressed there from the first preliminary pressure to the intermediate pressure, wherein, in a next step, the synthesis gas flows into a third compressor unit (16) and is compressed there from the intermediate pressure to the end pressure, wherein, when the mass flow of the synthesis gas flowing into the arrangement (1) is reduced below a mass flow limit value, a centrifugal compressor of the first compressor unit (4) and a centrifugal compressor of the second compressor unit (10) shut down.

Description

2024PF00799 1 Description TITLE Arrangement for compressing a synthesis gas and method for operating the arrangement TECHNICAL AREA

[0001] The invention relates to an arrangement for compressing a synthesis gas comprising a first compressor unit, wherein the first compressor unit is configured such that the synthesis gas is compressed from an initial pressure to a first pre-pressure, a second compressor unit, wherein the second compressor unit is configured such that the synthesis gas is compressed from the first pre-pressure to an intermediate pressure, and a third compressor unit, wherein the third compressor unit is configured such that the synthesis gas is compressed from the intermediate pressure to a final pressure.

[0002] The invention further relates to a method for operating an arrangement for compressing synthesis gas, wherein in a first step the synthesis gas is compressed in a first compressor unit from an initial pressure to a first pre-pressure, wherein in a second step the synthesis gas flows into a second compressor unit and is compressed there from the first pre-pressure to the intermediate pressure, wherein in a next step the synthesis gas flows into a third compressor unit and is compressed there from the intermediate pressure to the final pressure. BACKGROUND

[0003] Ammonia (NH3) is produced by the chemical reaction of hydrogen (H2) and nitrogen (N2). Ammonia is an important chemical, primarily used as a fertilizer in agriculture. The Haber-Bosch process is the most widely used industrial process for producing ammonia. It involves the reaction of hydrogen and nitrogen. 2024PF00799 2 at high temperatures and pressures in the presence of a catalyst. Despite its widespread use, the Haber-Bosch process has some disadvantages, such as high energy consumption and CO2 emissions.

[0004] It is desirable to provide a process for producing ammonia that is more efficient and environmentally friendly than existing methods. In particular, energy consumption should be reduced and CO2 emissions minimized. An ammonia production process comprises the following steps: Hydrogen production: Hydrogen is produced by the electrolysis of water. In this process, water (H2O) is split into its components hydrogen (H2) and oxygen (O2). The electrolysis is carried out using renewable energy, such as solar or wind power, to make the process sustainable. Nitrogen extraction: Nitrogen is extracted from the air, which consists of approximately 78% nitrogen. This is done by an air separation plant that separates the air into its components nitrogen (N2) and oxygen (O2). Ammonia synthesis: The produced hydrogen and the extracted nitrogen are combined in a reactor.The reaction takes place under elevated pressure and temperature in the presence of a catalyst, which accelerates the reaction. The catalyst can be iron or another suitable material.

[0005] The chemical reaction that takes place is as follows: N2 + 3H2 2NH3

[0006] The ammonia produced is separated from the reaction mixture and purified. This can be done by condensation and distillation to obtain pure ammonia. Using renewable energy for water electrolysis reduces energy consumption. The present invention provides an improved process for the production of ammonia that is more efficient and environmentally friendly than conventional processes. By utilizing renewable energies and minimizing CO2 emissions, the process contributes to sustainable development and offers an economically attractive alternative for the chemical industry. 2024PF00799 3

[0008] The hydrogen produced by water electrolysis is subject to significant fluctuations in mass flow rate due to changing wind conditions. Solar intensity is also subject to daily or seasonal variations. Consequently, the hydrogen flow required for further ammonia synthesis is subject to the same fluctuations.

[0010] While hydrogen production and synthesis gas supply are subject to significant fluctuations, the requirements on the demand side of the ammonia reactor remain constant with regard to the required pressure and temperature. The synthesis gas comprises hydrogen and nitrogen. [00" "" A reduction in the delivery rate of turbo compressors is generally possible down to 70% of a design rate without so-called blow-off. During blow-off operation, a certain amount is returned from the pressure side to the suction side. Without blow-off, damaging pump surges or... Pressure fluctuations within the compressor, which can lead to damage in the compressor.

[0012] For this reason, the individual compressor stages must be equipped with so-called bypass lines to ensure that a minimum permissible process gas volume is not undercut at the compressor stage inlet. This quantity is also the minimum process gas volume that can be operated without bypassing.

[0013] The volume flow rate used in the manufacturing process can still be reduced, but the compressor is operated in recirculation mode and the difference is transferred from the pressure side to the suction side.

[0014] The minimum process gas volume that can be operated without blow-off determines the minimum possible power consumption of the compressor stages, which cannot be reduced further even with a further reduction in the process gas volume. The minimum2024PF00799 4 The total power consumption of the entire compressor system is the sum of the power ratings of all compressor housings.

[0015] By combining a turbo compressor solution on the low-pressure side and a turbo compressor and piston compressor solution on the high-pressure side, the operating limitations of the turbo compressor resulting from fluid mechanics can be balanced with the advantages of the flexibility of the piston compressor.

[0016] This balance is achieved with a specially designed piston compressor, which complements the turbo compressors on the high-pressure side and the turbo compressors on the low-pressure side. SUMMARY OF THE INVENTION

[0017] This is where the invention comes in.

[0018] The object of the invention is to provide an arrangement and a method for compressing synthesis gas that allows for flexible driving.

[0019] This problem is solved by an arrangement for compressing a synthesis gas comprising a first compressor unit, wherein the first compressor unit is configured such that the synthesis gas is compressed from an initial pressure to a first pre-pressure, a second compressor unit, wherein the second compressor unit is configured such that the synthesis gas is compressed from the first pre-pressure to an intermediate pressure, a third compressor unit, wherein the third compressor unit is configured such that the synthesis gas is compressed from the intermediate pressure to a final pressure, wherein the second compressor unit comprises a turbo compressor and a piston compressor, wherein the turbo compressor and the piston compressor are arranged parallel to each other. The problem is also solved by a method for operating an arrangement for compressing synthesis gas, wherein in a first step the 2024PF00799 5 Synthesis gas is compressed in a first compressor unit from an initial pressure to a first pre-pressure, wherein in a second step the synthesis gas flows into a second compressor unit and is compressed there from the first pre-pressure to the intermediate pressure, wherein in a next step the synthesis gas flows into a third compressor unit and is compressed there from the intermediate pressure to the final pressure.

[0021] Advantageous embodiments are the subject of the dependent claims. ??' The dependent claims list further advantages that can be combined in any way to achieve further advantages. DESCRIPTION OF THE INVENTION When designing a turbo compressor solution for the compression of synthesis gas (hydrogen and nitrogen), an arrangement of two compressor housings with an integrated make-up stage as the last compressor stage on the high-pressure housing is usually designed.

[0024] When designing a combined arrangement with a turbo and piston compressor solution, the low-pressure stage is designed as a compressor housing with speed control or a variable inlet guide vane. Compression on the high-pressure side is achieved by a two-housing compressor train with a variable inlet guide vane and a parallel piston compressor. The so-called make-up stage is designed as a separate compressor housing, which compresses the entire process gas mass flow to the target pressure in a final impeller stage. The final pressure of the reactor for the production of ammonia is increased. 00?^ The design of the piston compressors takes into account the so-called turn-down cases that result from the operation of the turbo compressors on the high-pressure side and the low-pressure side, utilizing the entire 2024PF00799 6 Speed ​​characteristic map of the compressors on the low-pressure side and of the entire swirl characteristic map of the compressors on the high-pressure side.

[0026] The turn-down of the turbo compressors is carried out as described below.

[0027] The mass flow rate of the synthesis gas is reduced to the surge limit of the compressors on both the low-pressure and high-pressure sides at a constant target pressure. A further reduction in the flow rate on the high-pressure side is achieved by switching off the high-pressure compressors and operating the piston compressor. Additionally, operation is achieved by switching off one stage of the pre-compression on the low-pressure side and operating the remaining turbo compressors on the low-pressure side and the piston compressor and make-up compressor in series on the high-pressure side.

[0028] By further reducing the rotational speed along the surge line of the low-pressure compressor, the achievable final pressure is reached as the final pressure decreases down to the minimum possible rotational speed. The resulting volume flow to the piston compressor is reduced on the one hand by the turn-down of the turbo compressors and increased again on the other hand by the reduced intermediate pressure. This can result in the turbo compressors' turn-down state, at reduced pressure, representing the largest volume flow for the piston compressor. Simultaneously, the piston compressor must be designed to deliver the greatest relative pressure increase due to the reduced inlet pressure and constant target pressure. This can be achieved in the piston compressor without switching cylinder stages on or off.

[0030] According to the invention, a turn-down of up to 75% can be achieved by arrangement, i.e. to approximately 25% of the original amount of synthesis gas.

[0031] Furthermore, a pressure drop that can occur due to fluctuations in the hydrogen coming from electrolysis can be compensated for. 2024PF00799 7 Such a combination of turbo and piston compressors not only expands the possibility of turn-down operation without recirculation, but also saves up to 70% of power compared to a traditional synthesis gas compressor design with recirculation.

[0032] This allows for more flexible operation. Furthermore, fluctuations in process gas volume and pressure on the hydrogen production side are taken into account. The extended operating range avoids recirculation and the resulting fluctuations in hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] An embodiment of the invention will be explained in more detail below with reference to the following figures.

[0034] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings. Identical components or components with the same function are marked with the same reference numerals. Exemplary embodiments of the invention are described below with reference to the drawings. These drawings are not intended to be drawn to scale; rather, where helpful for explanation, they are presented in a schematic and / or slightly distorted form. For further details regarding the teachings directly apparent from the drawings, reference is made to the relevant prior art.

[0037] They show: FIG 1 a schematic representation of an arrangement according to the invention 2024PF00799 8 DESCRIPTION OF THE EXECUTION FORMS Figure 1 shows a schematic representation of an arrangement 1 according to the invention.

[0040] The arrangement 1 is designed for compressing synthesis gas and comprises a first supply line 2 and a second supply line 3. Synthesis gas is fed into the first supply line 2 and the second supply line 3. The synthesis gas consists of hydrogen and oxygen. The hydrogen originates from water electrolysis, which is powered by renewable energy sources, and therefore fluctuations in hydrogen production can occur. The oxygen is obtained, for example, from an air separation plant.

[0041] In normal operation, the synthesis gas flows in both the first supply line 2 and the second supply line 3 at an initial pressure between 2 and 8 bar, particularly at 5 bar. The first supply line 2 and the second supply line 3 are fluidically connected to an inlet of a first compressor unit 4. The first compressor unit 4 is designed such that the synthesis gas is compressed from an initial pressure to a first pre-pressure.

[0042] The first compressor unit 4 is configured with a first compressor 5 and a second compressor 6. The first compressor 5 is essentially identical in design to the second compressor 6. Both the first compressor 5 and the second compressor 6 compress the synthesis gas from the initial pressure to a first pre-pressure between 20 and 30 bar, in particular 25 bar. After the first compressor 5, the synthesis gas is present at outlet 7 at a pressure between 20 and 30 bar, in particular 25 bar. After the second compressor 6, the synthesis gas is present at outlet 8 at a pressure between 20 and 30 bar, in particular 25 bar. Outlet 7 and outlet 8 are routed to a common line 9. In the common line 9, the synthesis gas is present at the first pre-pressure. 2024PF00799 9 [0? 13' The first compressor 5 and the second compressor 6 are arranged parallel to each other. Furthermore, the first compressor 5 and the second compressor 6 are designed as turbo compressors, in particular centrifugal compressors.

[0044] The first compressor 5 and the second compressor 6 each include, after a stage, a feed to a cooling unit to cool the synthesis gas. After cooling, the synthesis gas is fed back to the first compressor 5 and the second compressor 6. This cooling unit is not shown in the figure.

[0045] Line 9 is fluidically connected to a second compressor unit 10. The second compressor unit 10 is designed such that the synthesis gas is compressed from the initial pre-pressure to an intermediate pressure. For this purpose, the second compressor unit 10 comprises a third compressor 11 and a fourth compressor 12. Line 9 is fluidically divided into a first line 13 and a second line 14. The first line 13 is fluidically connected to an inlet of the third compressor 11. The second line 14 is fluidly connected to an inlet of the fourth compressor 12.

[0047] In the third compressor 11, the pressure of the synthesis gas is increased from the initial inlet pressure to the intermediate pressure. In the fourth compressor 12, the pressure of the synthesis gas is increased from the initial inlet pressure to the intermediate pressure. The initial inlet pressure is between 20 and 30 bar, particularly 25 bar. The intermediate pressure is between 140 and 155 bar, particularly 147 bar. The third compressor 11 and the fourth compressor 12 are arranged parallel to each other.

[0048] The third compressor 11 is designed as a turbo compressor, specifically a centrifugal compressor. The fourth compressor 12 is designed as a piston compressor. The mass flow rate to the third compressor 11 differs from the mass flow rate to the fourth compressor 12. The mass flow rate is essentially divided, with between 60 and 80%, specifically 70%, flowing into the third compressor 11. 10 Compressor 11 and between 40 and 20%, especially 30%, flow to the fourth compressor.

[0049] The third compressor 11 and the fourth compressor 12 include, after one stage, a feed to a cooling unit to cool the synthesis gas. After cooling, the synthesis gas is fed back to the first compressor 5 and the second compressor 6. The cooling unit is not shown in the figure. The outlet of the third compressor 11 and the fourth compressor 12 is routed to a common line 15. From the common line 15, the synthesis gas is routed to an inlet of a third compressor unit 16. The third compressor unit 16 is configured such that the synthesis gas is compressed from an intermediate pressure to a final pressure. The final pressure is between 145 and 165 bar, in particular 155 bar. This final pressure is present at the outlet 18 of the fifth compressor 17.

[0051] The third compressor unit includes the fifth compressor 17. The fifth compressor 17 is designed as a turbo compressor, in particular as a centrifugal compressor, and is also referred to as the make-up stage.

[0052] During operation, fluctuations in the energy supply can lead to a reduction in the mass flow of synthesis gas to the first compressor unit 4. This reduction can be as high as 75%. In such cases, not all compressors in arrangement 1 are used. Specifically, the second compressor 6 and the third compressor 11 are deactivated, so that no mass flow passes through them. The synthesis gas then flows only through the remaining compressors of the first compressor unit 4 and the second compressor unit 10. In other words: If the mass flow rate of the synthesis gas flowing into arrangement 1 is reduced below a mass flow limit 2024PF00799 11 If this occurs, a centrifugal compressor (first compressor 5 or second compressor 6) of the first compressor unit 4 and a centrifugal compressor of the second compressor unit 10 will go out of service.

[54] According to arrangement 1, the synthesis gas is further processed in a subsequent process such that a chemical reaction is carried out in a reactor, resulting in the production of ammonia. This is not shown in the figure. Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by a person skilled in the art without leaving the scope of protection of the invention.

Claims

2024PF00799 12 Claims 1. Arrangement (1) for compressing a synthesis gas comprising a first compressor unit (4), wherein the first compressor unit (4) is designed such that the synthesis gas is compressed from an initial pressure to a first pre-pressure, a second compressor unit (10), wherein the second compressor unit (10) is designed such that the synthesis gas is compressed from the first pre-pressure to an intermediate pressure, a third compressor unit (16), wherein the third compressor unit (16) is designed such that the synthesis gas is compressed from intermediate pressure to a final pressure, wherein the second compressor unit (10) comprises a turbo compressor and a piston compressor, wherein the turbo compressor and the piston compressor are arranged parallel to each other.

2. Arrangement (1) according to claim 1 , the turbo compressor is designed as a centrifugal compressor.

3. Arrangement (1) for compaction according to claim 1 , wherein the first compressor unit (4) comprises a first compressor (5) and a second compressor (6), wherein the first compressor (5) and the second compressor (6) are arranged parallel to each other.

4. Arrangement (1) for compaction according to claim 3, wherein the first compressor (5) and the second compressor (6) are designed as turbo compressors.

5. Arrangement (1) according to claim 4, the turbo compressors are designed as centrifugal compressors. 2024PF00799 13 6. Arrangement (1) according to any one of the preceding claims, wherein the first compressor unit (4) comprises a first cooling unit, the first cooling unit being configured for cooling the synthesis gas.

7. Arrangement (1) according to any one of the preceding claims, wherein the second compressor unit (10) has a second cooling unit, wherein the second cooling unit is designed to cool the synthesis gas.

8. Arrangement (1) according to any one of the preceding claims, the synthesis gas comprises nitrogen dioxide N2 and hydrogen H2.

9. Method for operating an arrangement (1) for compressing synthesis gas, wherein in a first step the synthesis gas is compressed in a first compressor unit (4) from an initial pressure to a first pre-pressure, wherein in a second step the synthesis gas flows into a second compressor unit (10) and is compressed there from the first pre-pressure to the intermediate pressure, in a next step the synthesis gas flows into a third compressor unit (16) and is compressed there from the intermediate pressure to the final pressure.

10. Method according to claim 9, wherein the first compressor unit (4) is operated with two parallel centrifugal compressors.

11. Method according to claim 9 or 10, wherein the second compressor unit (10) is designed with a turbo compressor and a piston compressor, where the turbo compressor and the piston compressor are arranged parallel to each other. 2024PF00799 14 12. Method according to claim 11 , where the turbo compressor is designed as a centrifugal compressor.

13. Method according to any one of claims 9 to 12, the synthesis gas comprises nitrogen N2 and hydrogen H2.

14. Method according to one of claim 12, wherein if the mass flow of the synthesis gas flowing into the arrangement (1) is reduced below a mass flow limit value, a centrifugal compressor of the first compressor unit (4) and a centrifugal compressor of the second compressor unit (10) are taken out of operation.

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