BE1029758B1 - Ammonia Synthesis Device - Google Patents

Abstract

The present invention relates to an ammonia plant, the ammonia plant having a converter 10, a first heat exchanger 20 and a separation device 30, the converter 10 and the first heat exchanger 20 being connected to one another via a product gas connection 40 in such a way that the ammonia synthesis product gas from the converter 10 via is routed through the first heat exchanger 20 to the separation device 30, with the separation device 30 and the converter 10 being connected to one another via a feed gas connection 50 in such a way that the cycle gas is routed from the separation device 30 to the converter 10, with the ammonia plant having a hydrogen feed line 60, with the Hydrogen supply 60 is connected to the converter 10 via a second heat exchanger 80, characterized in that the ammonia plant has a first electrical heater 70, the ammonia plant having a steam turbine 90, the first electrical heater 70 being connectable to the converter 10 or the steam turbine 90 is.

Description

. BE2021/5727

Ammonia Synthesis Device

The invention relates to a device for the synthesis of ammonia.

Currently, mainly hydrogen is used for the ammonia synthesis via the

Steam reforming and a water gas shift reaction generated from natural gas. There

Methane (CHa) is converted into hydrogen (H2) and carbon dioxide (CO2), this leads to significant carbon dioxide emissions. In order to reduce this, hydrogen from other sources is increasingly being used, for example the electrolysis of water using electricity generated from renewable sources. However, this leads to further changes in the overall process, since natural gas is now used as a

Combustion gas source and the comparatively high combustion temperatures in the

entire process no longer available. This applies, for example, and in particular to the start-up of the device, the reactant gases first having to be brought to a temperature necessary for the ammonia synthesis before the

Overall process can be maintained by the exothermic reaction.

A small ammonia plant is known from US 2004/0219088 A1.

From EP 3 730 456 A1 the use of renewable energy in the

Ammonia synthesis known.

A device for heating a catalytic converter is known from US 2002/0098129 A1.

A hydrogen-generating device is known from US 2002/0090329 A1.

Another point is that as part of the cooling of the product gas stream after the ammonia synthesis, saturated water vapor is produced, for example at 330 °C at around 130 bar, which can only be used to a limited extent. So far, this saturated steam with the help of the combustion of natural gas, for example, in the use of waste heat

Steam reforming superheated to about 535 ° C and can then, for example, for

electricity generation or to drive the turbines of the compressors.

; BE2021/5727

The object of the invention is to solve the technical challenges arising from the elimination of steam reforming.

This problem is solved by an ammonia plant with the features specified in claim 1 . Advantageous developments result from the

Subclaims, the following description and the drawing.

The ammonia plant according to the invention has a converter, a first

Heat exchanger and a separation device. Become in the converter

Hydrogen and nitrogen converted into ammonia. But since it is a

Equilibrium reaction is, are in the ammonia synthesis product gas in addition to the product ammonia and the educts hydrogen and nitrogen. The

The converter and the first heat exchanger are connected to one another via a product gas connection in such a way that the ammonia synthesis product gas is routed from the converter via the first heat exchanger to the separation device. In the

Separator is the product ammonia from the

Ammonia synthesis product gas at least partially separated, leaving behind unreacted starting materials and possibly not separated product, ie a

Hydrogen-nitrogen-ammonia mixture, which is referred to as cycle gas.

The separation device and the converter are such a

Educt gas connection connected to each other that the cycle gas from the

Separation device is guided to the converter. This structure corresponds to the classic cycle within the Haber-Bosch process.

The ammonia plant has a hydrogen supply. The hydrogen supply can be connected to a hydrogen supply network, for example. Likewise, the hydrogen supply can be connected to a water electrolysis.

If the hydrogen source only provides hydrogen, for example in water electrolysis and not a hydrogen-nitrogen mixture, such as in steam reforming, the ammonia plant preferably also has air separation, with the nitrogen from the air separation being mixed with the

Hydrogen from the hydrogen feed is mixed before the gas mixture is compressed, heated and finally converted into ammonia in the converter.

The hydrogen feed is connected to the converter 5 via a second heat exchanger. The second heat exchanger will do that

Ammonia synthesis product gas are brought to the temperature of about 350 ° C to 400 ° C necessary for the reaction.

According to the invention, the ammonia plant has a first electric heater. The

Ammonia plant also has a steam turbine, for example to generate electricity or to drive the compressors. The first electric heater is with the

Converter or the steam turbine can be connected. This means that during the

Starting the first electric heater connected to the converter and in continuous control operation, the first electric heater is connected to the steam turbine. Connectable is thus preferably implemented by valves, so that a hydrogen-nitrogen

Mixture, with increasing ammonia content during start-up, from the second

Heat exchanger 80 supplied, heated there and the converter 10 is supplied, or can be superheated there during regular operation steam from the first heat exchanger 20 and passed to the steam turbine.

The first heat exchanger can also be constructed in a cascaded manner, that is to say it can consist, for example, of a first heat exchanger and a second first heat exchanger.

In a further embodiment of the invention, the first heat exchanger can be connected to the first electric heater in such a way that the water vapor generated in the first heat exchanger is fed into the first electric heater.

In a further embodiment of the invention, the second heat exchanger is connected to the converter in such a way that the educt gas flow from the second

Heat exchanger switchable directly or via the first electric heater in the

converter is performed.

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In a further embodiment of the invention, the steam turbine with a

Generator connected to produce electricity.

In a further alternative embodiment of the invention, the steam turbine is connected to a compressor.

In a further aspect, the invention relates to a method for starting and

Operating an ammonia plant according to the invention. During start-up, the first electric heater supplies the educt stream flowing into the converter.

After start-up in control mode, the first electric heater superheats steam from the first heat exchanger and the superheated steam is routed to the steam turbine.

The ammonia plant according to the invention is based on one in the

Drawing illustrated embodiment explained in more detail.

Fig. 1 Schematic representation of an ammonia plant

In Fig. 1 an ammonia plant according to the invention is shown schematically. From a hydrogen supply 60 hydrogen is supplied, for example, the

Hydrogen supply are fed from a hydrogen network or from a

water electrolysis. The second educt nitrogen is required, which by means of a

Air separation 110 is provided. These educts are fed together into a second heat exchanger and heated there by the product gas stream coming from the converter 10 . From this point it differs

Management between start-up and regular operation.

In control mode, the first valve 120 is closed and the second valve 130 is open. As a result, through the second heat exchanger 80 on

Reaction temperature heated educt gas stream 50 fed directly to the converter 10.

For this purpose, the educt gas flow 50 passes through the opened second valve 130, the first valve 120 is closed. In the converter 10, the reaction of hydrogen and

Nitrogen to ammonia, with the gas mixture warming up. The product gas flow is first passed from the converter 10 into a first heat exchanger 20

) BE2021/5727 and emits the heat generated during the reaction. Then the

Product gas stream 40 from the first heat exchanger 20 to the second

Heat exchanger 80 passed, where this emits more heat to the educt gas stream 50. The product gas stream 40 is then cooled and passed into the separation device 30 where the product ammonia is separated. Further heat exchangers can be arranged upstream of the separating device 30 in order to improve the gas mixture

continue to cool the separation. From the separating device 30 the gas mixture, which mainly comprises hydrogen and nitrogen and optionally ammonia, is returned to the circuit, for which purpose the separating device 30 is connected to the second heat exchanger 80 . The gas streams from the separator are before the second heat exchanger 80 with the hydrogen from the

Hydrogen supply 60 and the nitrogen from the air separation 110 combined.

In this case, these two gas streams can be compressed individually by two compressors, preferably before they are combined, in order to

process to achieve the necessary pressure. Joint compression is less preferred since the two gas streams have very different inlet pressures. The starting materials, the hydrogen from the hydrogen supply 60 and the

Nitrogen from the air separation 110 can be passed directly to or immediately before the separation device 30 for combining with the product stream 40 .

This is particularly preferred when the educt streams have the residual water and this is washed out in the separating device 30 together with the ammonia that has been separated off.

In addition to this cycle for synthesizing the ammonia, the one in the first

Heat exchanger 20 generated steam (saturated steam with, for example, 330 ° C and about 130 bar) passed through the open third valve 140 in the electric heater, heated there from, for example, about 330 ° C to, for example, 500 ° C to 550 ° C. When the fourth valve 150 is closed, the steam is guided via the open fifth valve 160 to the steam turbine 90, which drives a generator 100 in the example shown.

The start-up of the ammonia plant differs significantly from this regular operation. The third valve 140 and the fifth valve 160 are closed, there will be no

Steam directed to the steam turbine 90. The second valve 130 is also closed and the first valve 120 and the fourth valve 150 are open for this.

° BE2021/5727

As a result, the educts from the hydrogen supply 60 and the air separation 100 are now first conducted via the second heat exchanger 80 into the electric heater, heated there and from there into the converter 10. This process continues until the converter 10 is sufficiently hot so that the reaction runs to a sufficient extent and generates sufficient energy itself. Then the second valve 130 is opened and the first valve 120 and the fourth valve 150 are closed. If the reaction further accelerates, the third valve 140 and the fifth valve 160 are opened, water or steam is fed into the first heat exchanger 20, heated there to 330° C., for example, then fed into the electric heater 70, there for example 525° C. and from there fed to the steam turbine 90, which in turn uses the energy to drive the generator 100 and generate electricity, which is partly required for the electric heater 70.

Since the electric heater 70 is thus exposed to two different media, a flushing process can be provided between the two operating states that have been shown so far. For example, the first valve 120 and/or the third valve 140 can be designed as a three-way valve, with the third connection being able to be connected to the air separation unit 110, for example, in order to introduce nitrogen as flushing fluid. Likewise, additionally or alternatively, the fourth valve 150 and / or the fifth valve 160 can also be designed as a three-way valve, the third

Connection, for example, connected to a pump to the electrical in the

Heater 70 located gas volume to remove quickly.

Reference numeral 10 converter 20 first heat exchanger

separation device

Product gas stream 30 50 reactant gas stream 60 hydrogen supply 70 electric heater 80 second heat exchanger 90 steam turbine

' BE2021/5727 100 generator 110 air separation 120 first valve 130 second valve 140 third valve 150 fourth valve 160 fifth valve

Claims (6)

patent claims 1. Ammonia plant, wherein the ammonia plant has a converter (10), a first heat exchanger (20) and a separation device (30), the converter (10) and the first heat exchanger (20) being connected to one another in this way via a product gas connection (40). are that the ammonia synthesis product gas is routed from the converter (10) via the first heat exchanger (20) to the separation device (30), the separation device (30) and the converter (10) being connected to one another via an educt gas connection (50) in such a way that the circulating gas is conducted from the separation device (30) to the converter (10), the ammonia plant having a hydrogen feed (60), the hydrogen feed (60) being connected to the converter (10) via a second heat exchanger (80), thereby characterized in that the ammonia plant has a first electrical heater (70), the ammonia plant having a steam turbine (90), the first electrical heater (70) being connectable to the converter (10) or the steam turbine (90). 2. Ammonia plant according to claim 1, characterized in that the first heat exchanger (20) can be connected to the first electric heater (70) in such a way that the water vapor generated in the first heat exchanger (20) is guided into the first electric heater (70). 3. Ammonia plant according to one of the preceding claims, characterized in that the second heat exchanger (80) is connected to the converter (10) in such a way that the educt gas stream (50) can be switched from the second heat exchanger (80) directly or via the first electric heater (70) is guided into the converter (10). 4. Ammonia plant according to one of the preceding claims, characterized in that the steam turbine (90) is connected to a generator for generating electricity. 5. Ammonia plant according to one of claims 1 to 3, characterized in that the steam turbine (90) is connected to a compressor. ) BE2021/5727 6. Method for starting up and operating an ammonia plant according to one of the preceding claims, wherein during the start-up the first electric heater (70) heats the reactant stream (50) flowing to the converter (10), wherein after the start-up in regular operation the first electric heater ( 70) steam from the first heat exchanger (20) is superheated and the superheated steam is passed to the steam turbine (90).