WO2024189095A1

WO2024189095A1 - Combined system for producing steel, and method for operating the combined system

Info

Publication number: WO2024189095A1
Application number: PCT/EP2024/056695
Authority: WO
Inventors: Nils Tenhumberg
Original assignee: Thyssenkrupp Uhde Gmbh; Thyssenkrupp Ag
Priority date: 2023-03-16
Filing date: 2024-03-13
Publication date: 2024-09-19

Abstract

The invention relates to a combined system (1) for producing steel, said combined system comprising: a blast furnace (2) for producing pig iron; a converter steel mill (3) for producing crude steel; a blast furnace gas line system (4) for gases generated during the pig iron production; a composite line system (5) for gases generated during the pig iron production and/or crude steel production; a plant (6) for producing hydrogen or hydrogen-containing synthesis gas; a hydrogen line (8) for hydrogen-containing gases generated during the production of hydrogen or hydrogen-containing synthesis gas, the blast furnace gas line system (4) being connected to the plant (6) for producing hydrogen or hydrogen-containing synthesis gas as an input line into the plant (6) for producing hydrogen or hydrogen-containing synthesis gas, and the hydrogen line (8) being connected to the plant (6) for producing hydrogen or hydrogen-containing synthesis gas as an output line from the plant (6) for producing hydrogen or hydrogen-containing synthesis gas.

Description

Plant network for steel production and a method for operating the plant network

The invention relates to a plant network for steel production and a method for operating the plant network.

The steel production plant network includes a blast furnace for producing pig iron, a converter steelworks for producing crude steel, and a network of pipelines for gases that arise during pig iron production and/or crude steel production. In the blast furnace, pig iron is extracted from iron ores, additives, coke and other reducing agents such as coal, oil, gas, biomass, processed waste plastics or other materials containing carbon and/or hydrogen. The products of the reduction reactions are inevitably CO, CO2, and in particular hydrogen and water vapor. Blast furnace top gas extracted from the blast furnace process, which is also referred to as top gas and/or blast furnace gas, often has a high nitrogen content in addition to the aforementioned components and can also contain impurities. The amount of gas and the composition of the blast furnace top gas depend on the input materials and the operating mode and are subject to fluctuations. Typically, however, blast furnace top gas contains 35 to 60 vol.% N2, 20 to 30 vol.% CO, 20 to 30 vol.% CO2 and 2 to 15 vol.% H2. Around 30 to 40% of the blast furnace top gas produced during pig iron production is usually used to heat the hot blast for the blast furnace process in blast furnace heaters; the remaining blast furnace top gas can also be used externally in other plant areas for heating purposes or to generate electricity.

In the converter steelworks, which is downstream of the blast furnace process, pig iron is converted into crude steel. By blowing oxygen onto liquid pig iron, disruptive impurities such as carbon, silicon, sulphur and phosphorus are removed. Since the oxidation processes cause a strong development of heat, scrap is often added as a coolant in quantities of up to 25% based on the pig iron. Lime is also added to form slag and alloying agents. A converter gas is drawn off from the steel converter, which has a high CO content and also contains nitrogen, hydrogen and CO2. A typical converter gas composition has 50 to 70 vol.% CO, 10 to 20 vol.% N2, approx. 15 vol.% CO2 and approx. 2 vol.% H2. The converter gas is

REPLACEMENT BLADE (RULE 26) either flared or captured at modern steelworks and used for energy purposes.

In an integrated steelworks, which is operated in conjunction with a coking plant, around 40 to 50% of the raw gases produced as blast furnace top gas, converter gas and coke oven gas are used for process engineering processes. Around 50 to 60% of the resulting gases are fed to the power plant and used to generate electricity. The electricity generated in the power plant covers the electricity requirements for the production of pig iron and crude steel. Ideally, the energy balance is closed, so that apart from iron ore and carbon in the form of coal and coke as energy sources, no further energy input is necessary and no product leaves the plant complex other than crude steel and slag.

The current state of the art is problematic due to high CO2 emissions, particularly a large CO2 footprint.

The invention is therefore based on the object of improving the sustainability of the overall process and the CO2 balance, in particular CO2 emissions, and reducing the CO2 footprint while at the same time enabling stable, continuous and sustainable operation of plants.

This problem is initially solved by the features of patent claim 1. The plant network for steel production comprises a blast furnace for pig iron production, a converter steelworks for crude steel production, a blast furnace gas line system for gases that arise during pig iron production, a network line system for gases that arise during pig iron production and/or crude steel production, a plant for the production of hydrogen or hydrogen-containing synthesis gas. The plant network also comprises a hydrogen line for hydrogen-containing gases that arise during the production of hydrogen or hydrogen-containing synthesis gas, wherein the blast furnace gas line system is connected to the plant for the production of hydrogen or hydrogen-containing synthesis gas as an input line into the plant for the production of hydrogen or hydrogen-containing synthesis gas and the hydrogen line is connected to the plant for the production of hydrogen or hydrogen-containing synthesis gas as an output line from the plant for the production of hydrogen or hydrogen-containing synthesis gas. In the context of the present invention, a plant for producing hydrogen is understood to mean a plant for producing hydrogen, in particular a plant which provides hydrogen, for example a water-gas shift reaction plant, in particular by converting the CO content by a water-gas shift reaction (CO + H2O <=> CO2 + H2), a plant for separating hydrogen, in particular a hydrogen separation membrane plant or a combination thereof.

With the help of the hydrogen production plant, hydrogen-containing gases with different hydrogen concentrations can be provided, which can be used for a wide variety of synthesis reactions in possible chemical plants, whereby the chemical plant can be installed downstream of the hydrogen production plant.

In a first embodiment of the plant network according to the invention, it is provided that the plant for producing hydrogen or hydrogen-containing synthesis gas comprises a water-gas shift reaction plant and/or a hydrogen separation membrane plant, in particular the hydrogen separation membrane plant is connected downstream of the water-gas shift reaction plant in the flow direction.

In addition, in a further embodiment of the system network according to the invention, it can be provided that the system for producing hydrogen or hydrogen-containing synthesis gas additionally comprises a first system for CO2 separation, wherein the first system for CO2 separation is connected upstream of the hydrogen separation membrane system in the direction of flow. The first system for CO2 separation can in particular be connected to the network line system with a first CO2 line.

In a further advantageous embodiment of the plant network according to the invention, it is provided that the plant network additionally comprises a first CO2 switch for CO2 that arises in the first plant for CO2 separation, wherein the first CO2 switch is connected to the first CO2 line.

In preferred embodiments, the hydrogen separation membrane system can be configured to produce in the hydrogen-rich synthesis gas a stoichiometric mixture ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of 1 to 4.0, particularly preferably in the range of 2.0 to 3.8, most preferably in the range of 2.5 to 3.5.

In alternative embodiments, the hydrogen separation membrane system can be configured to set a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of greater than 4, preferably greater than 7, particularly preferably greater than 9 in the hydrogen-rich synthesis gas.

In a particularly preferred embodiment of the plant network according to the invention, an ammonia plant for producing ammonia from hydrogen-containing synthesis gas is provided in the plant for producing hydrogen or hydrogen-containing synthesis gas. The ammonia plant can, for example, be connected to the network control system, with the hydrogen line being connected to the network control system upstream of the ammonia plant in the direction of flow.

Ammonia is the second most produced synthetic chemical in the world. Ammonia is produced mainly from the elements hydrogen and nitrogen in the presence of an iron catalyst. The temperatures are often in the range between 400 °C and 500 °C and at a pressure of over 100 bar. The main factor for the process costs is the provision of hydrogen and nitrogen. Ammonia is therefore preferably produced based on the "Haber-Bosch process" from the elements according to equation [1]:

3 H2 + N2 ^ 2 NH3 + 92.28 kJ [1]

The plant for producing hydrogen or hydrogen-containing synthesis gas, here primarily containing hydrogen and nitrogen, means that the complex process of steam reforming can be omitted. Likewise, it is not necessary to produce the nitrogen from air separation if nitrogen is already produced during the production of hydrogen in the plant for producing hydrogen or a hydrogen-containing synthesis gas.

In order to remove small residual amounts of CO and CO ₂ , which act as catalyst poison, a further embodiment of the system according to the invention provides that in A methanation plant is arranged upstream of the ammonia plant in the direction of flow. The energy released during methanation can also be used to activate the reaction in the ammonia plant in order to operate the plant as energy efficiently as possible.

In another particularly preferred embodiment of the plant network according to the invention, a urea plant is provided for producing urea, with the ammonia plant being arranged upstream of the urea plant in the direction of flow. In the large-scale production of urea, the high-pressure synthesis of ammonia (NH3) and carbon dioxide (CO2) at around 150 bar and around 180 degrees Celsius is used almost exclusively. The two feedstocks are often obtained from a neighboring ammonia plant. In conjunction with the ammonia plant, ammonia would already be available as a reactant. In addition, CO2 can be obtained using the aforementioned CO2 separation plant and fed directly to the urea plant via the aforementioned CO2 switch.

Various processes are known in the art for producing particulate urea-containing compositions. In the past, urea particles were usually produced by spray crystallization, whereby a substantially anhydrous urea melt (water content of 0.1 to 0.3% by weight) is sprayed from the upper part of a spray crystallization tower into an ascending stream of air at ambient temperature and the drops solidify into crystals (prills). The prills obtained in this way have relatively small diameters and low mechanical strength.

The above-mentioned object is also achieved by a method for operating a plant network for steel production, which comprises a blast furnace for pig iron production, a converter steelworks for crude steel production, a blast furnace gas pipeline system for gases that arise during pig iron production, a network pipeline system for gases that arise during pig iron production and/or crude steel production, a plant for the production of hydrogen or hydrogen-containing synthesis gas, a hydrogen pipeline for hydrogen-containing gases that arise during the production of hydrogen or hydrogen-containing synthesis gas, wherein the blast furnace gas pipeline system is connected to the plant for the production of hydrogen or hydrogen-containing synthesis gas as an input line to the plant for the production of hydrogen or hydrogen-containing synthesis gas and the hydrogen pipeline is connected to the plant for the production of hydrogen or hydrogen-containing Synthesis gas is connected as an output line from the plant for producing hydrogen or hydrogen-containing synthesis gas, wherein in the plant for producing hydrogen or hydrogen-rich synthesis gas a mixed gas is set with a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen. The above statements regarding the plant network according to the invention also apply accordingly to the method according to the invention.

In a first embodiment of the method according to the invention, it is provided that the plant network additionally comprises an ammonia plant for producing ammonia from the hydrogen-containing synthesis gas of the plant for producing hydrogen or hydrogen-containing synthesis gas. The ammonia plant can, for example, be connected to the network control system and the hydrogen line can be connected to the network control system upstream of the ammonia plant in the direction of flow. The plant for producing hydrogen or hydrogen-rich synthesis gas sets a mixed gas for ammonia synthesis, with a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range from 1 to 4.0, particularly preferably in the range from 2.0 to 3.8, very particularly preferably in the range from 2.5 to 3.5. In this way, an advantageous stoichiometric ratio of hydrogen to nitrogen for ammonia synthesis is obtained.

In a further embodiment of the method according to the invention, it is provided that in the plant for producing hydrogen or hydrogen-rich synthesis gas, a hydrogen-rich gas is produced with a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of greater than 4, preferably greater than 7, particularly preferably greater than 9. In this way, a hydrogen-rich gas can be adjusted to, for example, 90 mol% hydrogen at a ratio of 9:1. Due to the high degree of purity of the hydrogen obtained in this way, it can be used for a variety of different technical applications without synthesizing ammonia from it. Other chemical plants that use hydrogen as a reactant are conceivable. Part of the hydrogen obtained could also be used as an energy source for other applications in a plant complex. Preferably, the plant for producing hydrogen or hydrogen-rich synthesis gas can comprise a water-gas shift reaction plant, a first plant for CO ₂ separation and a hydrogen separation membrane plant arranged downstream of one another in the direction of flow, wherein the hydrogen separation membrane plant sets the stoichiometric mixing ratio.

Advantageously, in a further embodiment of the method according to the invention, it can be provided that the system network additionally comprises: a first system for CO2 separation and a urea system, wherein the first system for CO2 separation is connected upstream of the hydrogen separation membrane system in the direction of flow, wherein the first system for CO2 separation is connected to the composite line system with a first CO2 line, in particular the first CO2 line is connected to the composite line system upstream of the urea system in the direction of flow to the composite line system and a first CO2 switch for CO2 which arises in the first system for CO2 separation, wherein the first CO2 switch is connected to the first CO2 line. It is intended that the first CO2 switch will provide CO2 for the urea plant and that the stoichiometric ratio of the CO2 provided for the urea plant with a stoichiometric quotient of a dividend with the molar amount of CO2 and a divisor with the molar amount of ammonia will be in the range 0.2 - 0.7. In this way, a CO2 to NH3 ratio can be set that is required for later urea synthesis in the urea plant.

Overall, the plant can be used flexibly to produce hydrogen or a hydrogen-containing synthesis gas in order to provide the optimal stoichiometric ratios for various synthesis reactions.

The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless stated otherwise in individual cases.

The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show:

Figure 1 is a simplified schematic representation of a plant network for steel production with a downstream ammonia plant and Figure 2 shows the block diagram according to Figure 1 with an additional urea plant.

In Figure 1, according to an embodiment of the invention, a plant network 1 for steel production is shown with a blast furnace 2 for pig iron production, a converter steelworks 3 for crude steel production. The plant network comprises a blast furnace gas line system 4 for gases that arise during pig iron production, a network line system 5 for gases that arise during pig iron production and/or crude steel production, a plant 6 for producing hydrogen or hydrogen-containing synthesis gas and an ammonia plant 7. The ammonia plant 7 is connected downstream of the plant 6 for producing hydrogen or hydrogen-containing synthesis gas.

The blast furnace gas piping system 4 is connected to the plant 6 for producing hydrogen or hydrogen-containing synthesis gas as an input line into the plant 6 for producing hydrogen or hydrogen-containing synthesis gas and the hydrogen line 8 is connected to the plant 6 for producing hydrogen or hydrogen-containing synthesis gas as an output line from the plant 6 for producing hydrogen or hydrogen-containing synthesis gas. The plant 6 for producing hydrogen or hydrogen-containing synthesis gas is represented as a water-gas shift reaction plant 9 and a hydrogen separation membrane plant 10, 10'.

The system 6 for producing hydrogen or hydrogen-containing synthesis gas can provide a gas mixture that largely contains hydrogen and nitrogen. A first system for CO2 separation 11 is connected upstream of the hydrogen separation membrane system 10, 10' in the direction of flow. The first system for CO2 separation 11 has a first CO2 line 12 with which it can be connected to the composite line system 5. A first CO2 switch 13 for CO2 that arises during the CO2 separation 11 is connected to the first CO2 line 12.

If CO2 is separated from the gas mixture, it is possible to provide a synthesis gas that is used to synthesize ammonia. For this purpose, the ammonia plant 7 is connected downstream of the plant 6 for producing hydrogen or hydrogen-containing synthesis gas. In the ammonia plant 7, ammonia is produced from a gas mixture with a stoichiometric ratio of hydrogen to nitrogen of 3 to 1. synthesized. A methanation plant 14 is connected upstream of the ammonia plant 7. Energy released from the methanation plant 14 can be used for the ammonia plant 7.

The hydrogen separation membrane system 10, 10' can be configured to set a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range from 1 to 4.0, particularly preferably in the range from 2.0 to 3.8, most preferably in the range from 2.5 to 3.5 in the hydrogen-rich synthesis gas. This is preferably intended for use of the synthesis gas for ammonia production.

In particular for other purposes, the hydrogen separation membrane system 10, 10' can also be configured to set a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of greater than 4, preferably greater than 7, particularly preferably greater than 9 in the hydrogen-rich synthesis gas.

The configuration of the hydrogen separation membrane system 10, 10' to set the desired stoichiometric mixing ratio can be done, for example, by selecting the type and number of separation membranes used and their connection. This selection is preferably made depending on the composition of the gas in the input line of the system 6 for producing hydrogen or hydrogen-containing synthesis gas. Connecting several membranes in series can, for example, lead to increased separation of nitrogen and thus increase the hydrogen content in the hydrogen-containing synthesis gas that passes through. Furthermore, the stoichiometric mixing ratio can be influenced by setting the pressure ratio of the gas pressure in the flow direction upstream and downstream of the hydrogen separation membrane system 10, 10'.

A coke oven plant 15 is connected to the interconnected pipeline system 5.

In Figure 2, a urea plant 16 is provided in addition to the ammonia plant 15. In the urea plant 16, the high-pressure synthesis of ammonia (NH3) and carbon dioxide (CO2) is used at about 150 bar and about 180 degrees Celsius. Ammonia can already be obtained as a reactant from a neighboring ammonia plant 7. In addition, C02 can be obtained by means of the aforementioned CO2 separation plant 11 and fed directly to the urea plant 16 via the aforementioned CO2 switch 14.

Reference symbol

1 Plant network

2 blast furnace

3 Converter steelworks

4 Blast furnace gas pipeline system

5 Integrated control system

6 Plant for the production of hydrogen or hydrogen-containing synthesis gas

7 Ammonia plant

8 Hydrogen line

9 Water-gas shift reaction plant

10, 10‘ Hydrogen separation membrane plant

11 CO2 capture plant

12 First C02 line

13 First C02 switch

14 Methanisation plant

15 Coke oven plant

16 Urea plant

Claims

Patent claims

1. Plant network (1) for steel production, comprising a blast furnace (2) for pig iron production, a converter steelworks (3) for crude steel production, a blast furnace gas line system (4) for gases that arise during pig iron production, a network line system (5) for gases that arise during pig iron production and/or crude steel production, a plant (6) for producing hydrogen or hydrogen-containing synthesis gas, a hydrogen line (8) for hydrogen-containing gases that arise during the production of hydrogen or hydrogen-containing synthesis gas, wherein the blast furnace gas line system (4) is connected to the plant (6) for producing hydrogen or hydrogen-containing synthesis gas as an input line into the plant (6) for producing hydrogen or hydrogen-containing synthesis gas and the hydrogen line (8) is connected to the plant (6) for producing hydrogen or hydrogen-containing synthesis gas as an output line from the plant (6) for producing hydrogen or hydrogen-containing synthesis gas.

2. Plant network (1) according to claim 1, characterized in that the plant (6) for producing hydrogen or hydrogen-containing synthesis gas comprises a water-gas shift reaction plant (9) and/or a hydrogen separation membrane plant (10, 10'), in particular the hydrogen separation membrane plant (10, 10') is connected downstream of the water-gas shift reaction plant (9) in the flow direction.

3. Plant network (1) according to claim 2, characterized in that the plant for producing (6) hydrogen or hydrogen-containing synthesis gas additionally comprises a first plant for CO ₂ separation (11), wherein the first plant for CO ₂ separation (11) is connected upstream of the hydrogen separation membrane plant (10, 10') in the flow direction.

4. Plant network (1) according to claim 3, characterized in that the first plant for CO ₂ separation (11) is connected to the composite line system (5) by a first CO ₂ line (12).

5. Plant network (1) according to claim 4, characterized in that the plant network (1) additionally comprises a first CO ₂ switch (13) for CO ₂ which arises in the first plant for CO ₂ separation (11), wherein the first CO ₂ switch (13) is connected to the first CO ₂ line (12).

6. Plant network (1) according to one of claims 2 to 5, characterized in that the

Hydrogen separation membrane system (10, 10') is configured to set in the hydrogen-rich synthesis gas a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range from 1 to 4.0, particularly preferably in the range from 2.0 to 3.8, most preferably in the range from 2.5 to 3.5.

7. Plant network (1) according to one of claims 2 to 5, characterized in that the

Hydrogen separation membrane system (10, 10') is configured to set a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of greater than 4, preferably greater than 7, particularly preferably greater than 9, in the hydrogen-rich synthesis gas.

8. Plant network (1) according to one of claims 1 to 6, characterized in that an ammonia plant (7) for producing ammonia from hydrogen-containing synthesis gas of the plant (6) for producing hydrogen or hydrogen-containing synthesis gas is provided.

9. Plant network (1) according to claim 7, characterized in that a methanation plant (14) is arranged upstream of the ammonia plant (7) in the flow direction.

10. Plant network (1) according to claim 8 or 9, characterized in that a urea plant (16) is provided for producing urea, wherein the ammonia plant (7) is arranged upstream of the urea plant (1) in the flow direction.

11. Method for operating a plant network (1) for steel production, which comprises a blast furnace (2) for pig iron production, a converter steelworks (3) for crude steel production, a blast furnace gas line system (4) for gases that arise during pig iron production, a network line system (5) for gases that arise during pig iron production and/or crude steel production, a plant (6) for producing hydrogen or hydrogen-containing synthesis gas, a hydrogen line (8) for hydrogen-containing gases that arise during the production of hydrogen or hydrogen-containing synthesis gas, wherein the blast furnace gas line system (4) is connected to the plant for producing hydrogen or hydrogen-containing synthesis gas as an input line into the plant (6) for producing hydrogen or hydrogen-containing synthesis gas and the hydrogen line (8) is connected to the plant (6) for producing hydrogen or hydrogen-containing synthesis gas as an output line from the plant (6) for producing hydrogen or hydrogen-containing synthesis gas, wherein in the plant (6) for producing hydrogen or hydrogen-containing synthesis gas a mixed gas is adjusted to a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen.

12. The method according to claim 11, wherein the plant network (1) additionally comprises an ammonia plant (7) for producing ammonia from the hydrogen-containing synthesis gas of the plant (6) for producing hydrogen or hydrogen-containing synthesis gas, characterized in that the plant (6) for producing hydrogen or hydrogen-rich synthesis gas sets a mixed gas for ammonia synthesis with a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range from 1 to 4.0, particularly preferably in the range from 2.0 to 3.8, most preferably in the range from 2.5 to 3.5.

13. The method according to claim 11, characterized in that in the plant (6) for producing hydrogen or hydrogen-rich synthesis gas, a hydrogen-rich gas is produced with a stoichiometric mixing ratio of a dividend with the molar amount of hydrogen and a divisor with the molar amount of nitrogen in the range of greater than 4, preferably greater than 7, particularly preferably greater than 9.

14. The method according to claim 12 or 13, characterized in that the plant (6) for producing hydrogen or hydrogen-rich synthesis gas comprises a water-gas shift reaction plant (9), a first plant for CO ₂ separation (11) and a hydrogen separation membrane plant (10, 10') arranged downstream of one another in the flow direction, the hydrogen separation membrane plant (10, 10') setting the stoichiometric mixing ratio.

15. Method for operating a system network (1) according to one of claims 11 or 12, wherein the system network (1) additionally comprises a first system for CO ₂ separation (11) and a urea system (16), wherein the first system for CO ₂ separation (11) is connected upstream of the hydrogen separation membrane system (10, 10') in the flow direction, wherein the first system for CO ₂ separation (11) is connected to the network line system (5) with a first CO ₂ line (12), in particular the first CO ₂ line (12) is connected to the network line system (5) upstream of the urea system (16) in the flow direction to the network line system (5) and a first CO ₂ switch (13) for CO ₂ which is produced in the first system for CO ₂ separation (11), wherein the first CO ₂ switch (13) is connected to the first CO ₂ -line (12) is connected, characterized in that with the first CO ₂ switch (13) CO ₂ is provided for the urea plant (16) and the stoichiometric ratio of the CO ₂ provided for the urea plant with a stoichiometric quotient of a dividend with the molar amount of CO ₂ and of a divisor with the molar amount of ammonia is in the range 0.2 -0.7.