BE1030241B1 - Plant for producing ammonia - Google Patents

Abstract

The present invention relates to a plant 10 for producing ammonia, the plant 10 having a reformer 20, a carbon dioxide separator 40 and a recirculation circuit 50 with a converter 52 and an ammonia separator 54, the reformer 20 being designed to convert hydrocarbon into hydrogen, wherein the reformer 20 is connected to the carbon dioxide separator 40 in a gas-carrying manner, the carbon dioxide separator 40 is connected in a gas-carrying manner to the recirculation circuit 50, the recirculation circuit 50 having an outlet 60, the outlet 60 being connected to an argon separator 100, the argon separator 100 having an argon outlet 102 and an educt gas outlet 101, wherein the educt gas outlet 101 is connected to the reformer 20 in a gas-carrying manner.

Description

Plant for producing ammonia

The invention relates to a plant for producing ammonia. One in particular

System that contains both hydrogen, which is produced using a reformer, for example

Natural gas is used as well as hydrogen, which is produced using electrolysis, particularly using renewable energies.

The current trend is for ammonia production plants to use a proportion of the

Hydrogen is produced and used in a CO2-neutral manner, in particular by means of electrolysis.

However, to meet the high demand, hydrogen from conventional sources will continue to be used

Sources used. While in a classic reforming this...

The ratio of hydrogen to nitrogen can be adjusted to an optimal ratio of 3:1. Nowadays, the requirement is to provide a higher proportion of nitrogen.

For example, if two thirds of the hydrogen is produced conventionally and one third by electrolysis, the gas stream coming from the reformer should have a hydrogen to nitrogen ratio of only 2:1. At about the same

The amount of hydrogen from both sources is even 1.5:1.

In order to be able to provide the additionally required nitrogen, air separation is known, for example.

From the subsequently published DE 10 2021 210 549 there is a method for producing

Ammonia is known.

However, additional air separation has the disadvantage that the investment for the system increases without creating any added value. This also increases the energy requirement, which in turn worsens the CO2 balance.

The object of the invention is to provide a system that has the necessary

Nitrogen content can be provided in a value-adding and low-emission manner.

This task is solved by the system with those specified in claim 1

characteristics. Advantageous further developments result from the subclaims, the following description and the drawing.

? BE2022/5069

The system according to the invention is used to produce ammonia. The basic one

The principle of Haber-Bosch synthesis has been known for about a century.

Hydrogen and nitrogen are combined at high pressure and elevated temperature

Catalyst as part of an equilibrium reaction, so that the ammonia product is separated off and the unreacted starting materials are circulated. The

The system has a reformer, a carbon dioxide separator and a

Recirculation circuit with a converter and an ammonia separator. The

Reformer is designed to convert hydrocarbon to hydrogen. It can be, for example, a steam reformer or an autothermal reformer.

The reformer is connected to the carbon dioxide separator in a gas-carrying manner. In the

The carbon dioxide is separated using a carbon dioxide separator. This can either be discarded, i.e. released into the environment. However, this can also be used for further purposes, for example in the synthesis of urea from the produced

Ammonia can be used. The carbon dioxide separator is connected to the recirculation circuit in a gas-conducting manner for the gas stream freed from carbon dioxide. A compressor is preferably arranged between the carbon dioxide separator and the recirculation circuit in order to achieve compression of the educt gas mixture. The

Recirculation circuit has a drain. The indulgence serves to take part of the im

To separate the circulating gas mixture. This is necessary because otherwise inert components, such as argon and/or methane, continue to accumulate.

As a result, the partial pressure of the reactants hydrogen and nitrogen decreases at a constant

pressure, so the production capacity of the plant would decrease over time. These inert components can be partially removed via the drain, although valuable educts are also lost. Typically, these gases are fed to thermal utilization, for example the combustion chamber of a primary reformer, preferably after ammonia has been separated off. Optionally the can also be used

Hydrogen, for example cryogenically separated and at least partially recycled. However, since this gas stream consists mainly of nitrogen, hydrogen, argon and

Methane exists, this gas stream is a comparatively valuable starting material. The drain is therefore connected to an argon separator. The argon separator has one

Argon outlet and an educt gas outlet. The educt gas outlet is connected to the reformer in a gas-conducting manner for the value-added return of nitrogen.

) BE2022/5069

Since an argon separator usually separates argon cryogenically, the process is, on the one hand, technically and energetically complex. On the other hand, however, the argon obtained as a by-product itself represents a value as a product and therefore this process is worthwhile just for the extraction of the argon.

The return of the other educt gases to the reformer is therefore for the actual

Process therefore possible without non-value-adding investment and energy expenditure. One

However, recirculation is not possible without an argon separator because the process would then lose a sink for the inert gas.

In a further embodiment of the invention, the reformer is a steam reformer with a primary reformer and a secondary reformer. The educt gas outlet is connected to the secondary reformer in a gas-carrying manner. That means that the one from the

Gas stream coming from the primary reformer is preferably combined with the gas stream coming from the educt outlet and fed to the secondary reformer. In addition, air is usually supplied to the secondary reformer, on the one hand for the oxygen for burning the hydrocarbon and thus for energy generation and on the other hand for the nitrogen, which is required in the actual ammonia synthesis.

In a further embodiment of the invention, the system has a

Water electrolysis device. The water electrolysis device has one

Hydrogen outlet on. The hydrogen outlet is connected to the recirculation circuit. A compressor is preferably arranged between the hydrogen outlet and the recirculation circuit. Since the compression of pure hydrogen is difficult due to its low molecular weight, the hydrogen is extracted from the

Hydrogen outlet is combined with the gas stream coming from the carbon dioxide separator and compressed together in a compressor. The advantage is that the usual nitrogen to hydrogen composition for the process is 1:3, which simplifies the compression of the gas mixture in the compressor.

In a further embodiment of the invention, the water electrolysis device has at least a first energy generating device for generating renewable energy

Energy connected. The first energy generating device is preferably a solar field, a wind farm, a hydroelectric power plant or a biogas power plant. This is preferred

* BE2022/5069

Water electrolysis device with a first and a second

Energy generating device connected to generate renewable energy. This has the advantage that the usually fluctuating production of renewable energy can be at least partially compensated. For example, the first is

Energy generating device a solar field and the second

Energy generating device a wind farm.

In a further embodiment of the invention there is between the drain and the

Argon separator arranged a hydrogen separator. The hydrogen separator has a residual gas outlet and a synthesis gas outlet for the hydrogen-enriched gas. The synthesis gas outlet carries gas with the

Recirculation circuit connected. The residual gas outlet carries gas with the

Argon separator connected. This can be preferred if the hydrogen-enriched gas obtained in this way is produced at a higher pressure level, for example 30 bar. For example, the hydrogen separator has a gas cleaning membrane, in particular made of palladium or a palladium alloy. Alternatively, the

Hydrogen separator must be cryogenic.

In a further embodiment of the invention there is between the reformer and the

Carbon dioxide separator arranged in a water gas shift reactor. This can be done by:

Gas mixture water vapor is additionally supplied to convert carbon monoxide with water to carbon dioxide and hydrogen.

In a further embodiment of the invention, the argon separator has a

Hydrogen outlet on. This is preferred if the argon separator works cryogenically. In this case, an upstream hydrogen separator can be dispensed with and both can be connected in a common device. The advantage is that the gas mixture only needs to be cooled down significantly once.

In a further aspect, the invention relates to a method for retrofitting an existing plant for the production of ammonia, the plant being one

Electrolysis device is expanded to produce hydrogen. Preferably, at least one first energy generating device for generating renewable energy is additionally added. This can either reduce the amount of fossil

> BE2022/5069 produced hydrogen can be reduced or the total amount of produced

Ammonia can be increased. In order to provide the nitrogen for this additional hydrogen, an argon separator is further added and the discharge begins

Recirculation circuit connected. Furthermore, the educt gas outlet carries gas with the

associated with reformers.

The system according to the invention is explained in more detail below using an exemplary embodiment shown in the drawing.

Fig. 1 Schematic representation of the system

The system 10 is shown schematically in FIG. Through an educt feed 23 the

Primary reformer 21 of reformer 20 supplied methane and water vapor. The

The primary reformer is heated by means of fuel supplied via the combustion supply 24

Fuel gas, the exhaust gases 25 are released accordingly. This in particular

Gas mixture consisting of water vapor, methane, hydrogen and carbon monoxide

The primary reformer is transferred to the secondary reformer 22 of the reformer 20 and mixed there with air, i.e. an oxygen-nitrogen mixture, via the air supply 26. The

Combustion generates the energy required for further reforming; the nitrogen is required for ammonia synthesis. The gas mixture comes out of the

Secondary reformer 22 water gas shift reactor 30 by using carbon monoxide

Water vapor is converted into carbon dioxide and hydrogen. The gas mixture then reaches the carbon dioxide separator 40. There the carbon dioxide is separated and released via the carbon dioxide outlet 42, for example at one of the

Appendix 10 downstream urea synthesis. The educt gas mixture is made from the

Educt gas outlet 41 is transferred to the recirculation circuit 50. Between the

Educt gas outlet 41 and the recirculation circuit 50 is one not shown here

Methanation and a compressor K arranged.

In addition, the system 10 has an energy generation device 70, for example a solar field. With the electricity generated in this way regeneratively, without carbon dioxide emissions, hydrogen is produced in a water electrolysis device 80 and via the

Hydrogen outlet 82 with that coming from the carbon dioxide separator 40

Gas stream combined and passed together through the compressor K.

° BE2022/5069

Various circuits are known for the recirculation circuit 50; they differ mainly in the point at which the combining of the

educt gas mixture and the recirculate takes place and where the liquid ammonia is separated (for example see also Max Appl, Ammonia, Principles and Industrial

Practice, Wiley-VCH, Weinheim, 1999, ISBN 3-527-29593-3, especially page 145,

Fig. 77). In the simplified circuit shown as an example in FIG

Recirculation circuit 50, the educt gas mixture is combined with the recirculate and passed through the ammonia separator 54. There the product ammonia is separated and released together with the residual water from the educt gas mixture via the ammonia drain 55. In order to be able to discharge inert gases, in particular methane and argon, a drain 60 is arranged in the recirculation circuit 50, in which a partial flow is removed from the recirculation circuit 50. The non-separated recirculating one

Gas flow is after the ammonia separator 54 via a heat exchanger W

Compressor K and another heat exchanger W are fed to the converter 52 and converted proportionately into ammonia in the converter 52. That emerging from the converter 52

Gas mixture is fed to the ammonia separator 54 via a heat exchanger W.

The gas mixture separated at the outlet 60 is initially passed through a

Ammonia recovery 61 led into an optional hydrogen separator 90. The hydrogen separated in the hydrogen separator 90 is passed through a

Synthesis gas outlet 91 is combined with the educt gas stream and fed back to the synthesis. The remaining gases, mainly nitrogen, hydrogen, argon, and

Methane, are fed to the argon separator 100 via the residual gas outlet 92. The argon is removed via the argon outlet 102 and can be marketed as an independent product. The gases that are valuable for synthesis are transported via the

Educt gas outlet 101 is fed to the secondary reformer 22. The one from the

Ammonia outlet 62 of the ammonia recovery 61 coming ammonia can, for example, with the ammonia from the ammonia outlet 55 of the

Ammonia separator 54 can be combined or used separately.

Reference number 10 attachment 20 reformer 21 primary reformer

/ BE2022/5069 22 Secondary reformer 23 Educt supply 24 Combustion supply 25 Exhaust gas 26 Air supply 30 Water gas shift reactor 40 Carbon dioxide separator 41 Educt gas outlet 42 Carbon dioxide outlet 50 Recirculation circuit 52 Converter 54 Ammonia separator 55 Ammonia outlet 60 Drain 61 Ammonia recovery 62 ammonia outlet 70 power generation device 80 water electrolysis device 81 water supply 82 hydrogen outlet 90 hydrogen separator 91 Synthesis gas outlet 92 Residual gas outlet 100 Argon separator 101 Educt gas outlet 102 Argon outlet

K compressor

W heat exchanger

Claims (7)

° BE2022/5069 patent claims 1. Plant (10) for producing ammonia, the plant (10) having a reformer (20), a carbon dioxide separator (40) and a recirculation circuit (50) with a converter (52) and an ammonia separator (54), the Reformer (20) is designed to convert hydrocarbon into hydrogen, the reformer (20) being connected to the carbon dioxide separator (40) in a gas-carrying manner, the carbon dioxide separator (40) being connected to the recirculation circuit (50) in a gas-carrying manner, the recirculation circuit (50 ) has an outlet (60), the outlet (60) being connected to an argon separator (100), the argon separator (100) having an argon outlet (102) and an educt gas outlet (101), the educt gas outlet (101) carrying gas with it the reformer (20) is connected. 2. Plant (10) according to claim 1, characterized in that the reformer (20) is a steam reformer with a primary reformer (21) and a secondary reformer (22), the educt gas outlet (101) being connected to the secondary reformer (22) in a gas-carrying manner . 3. Plant (10) according to one of the preceding claims, characterized in that the plant (10) has a water electrolysis device (80), the water electrolysis device (80) having a hydrogen outlet (82), the hydrogen outlet (82) being connected to the recirculation circuit (50) is connected. 4. Plant (10) according to claim 3, characterized in that the water electrolysis device (80) is connected to at least a first energy generating device (70) for generating renewable energy. 5. Plant (10) according to one of the preceding claims, characterized in that a hydrogen separator (90) is arranged between the outlet (60) and the argon separator (100), the hydrogen separator (90) having a residual gas outlet (92) and a synthesis gas outlet (91) for the hydrogen-enriched gas, the synthesis gas outlet (91) is connected to the recirculation circuit (50) in a gas-carrying manner, the residual gas outlet (92) being connected to the argon separator (100) in a gas-carrying manner. 6. Plant (10) according to one of the preceding claims, characterized in that a water-gas shift reactor (30) is arranged between the reformer (20) and the carbon dioxide separator (40). 7. Plant (10) according to one of the preceding claims, characterized in that the argon separator (100) has a hydrogen outlet.