Method and plant for providing hydrogen process gas with a target temperature for a high-temperature process, as well as plant layout

Abstract

The invention relates to a method for providing hot hydrogen process gas (GH2) at a target temperature (T Soll ) for a high-temperature process, in particular an iron ore direct reduction process, in which methane-containing gas (GCH4) is fed to a pyrolysis reactor (110) and is split in this pyrolysis reactor (110) by pyrolysis reaction into hydrogen process gas (GH2) and carbon (C), wherein the hot hydrogen process gas (GH2) exiting the pyrolysis reactor (110) is fed to a cooling unit in which the hot hydrogen process gas (GH2) is cooled to the set temperature (T Soll ) is cooled, whereby the waste heat generated from the hydrogen process gas (GH2) is used to preheat the methane-containing gas (GCH4) before it enters the pyrolysis reactor (110).

Description

[0001] The invention relates to a method and a system for providing hydrogen process gas at a target temperature for a high-temperature process, in particular an iron ore direct reduction process. The invention further relates to a system arrangement comprising a high-temperature system and such a system for providing hydrogen process gas.

[0002] To produce steel in a carbon-neutral (CO2-neutral) or at least CO2-reduced manner, it is desirable that the hydrogen process gas used in the necessary high-temperature process be produced in a climate-neutral way. For example, a direct reduction process of iron ore can be used as a high-temperature process for steel production. In a corresponding direct reduction plant, iron ore products are reduced to sponge iron through the use of process gases, which is then further processed into crude steel in an electrically operated furnace, such as an electric arc furnace. The hydrogen process gas used in this process must be heated to a temperature between 850°C and 1,100°C for application in the high-temperature process, especially the direct reduction process. A gas-fired preheater, particularly one powered by natural gas, is typically used to heat the hydrogen process gas.However, this type of heating process produces undesirable carbon dioxide emissions. Furthermore, it requires a large quantity of natural gas.

[0003] The invention is based on the objective of providing a method, a plant and a plant arrangement in which a hydrogen process gas with a target temperature for a high-temperature process can be provided in a way that is as climate-neutral as possible.

[0004] The problem is solved according to the invention by the features of the independent claims. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0005] The process according to the invention is characterized in that, to provide hydrogen process gas at a target temperature for a high-temperature process, in particular an iron ore direct reduction process, methane-containing gas is fed to a pyrolysis reactor and split in this pyrolysis reactor into hydrogen process gas and carbon by means of a pyrolysis reaction, wherein the hot hydrogen process gas exiting the pyrolysis reactor is fed to a cooling unit in which the hot hydrogen process gas is cooled to the target temperature, wherein the waste heat generated in the process by the hydrogen process gas is used to preheat the methane-containing gas before it enters the pyrolysis reactor.

[0006] The methane-containing gas can be fed into the pyrolysis reactor at a relatively low temperature. Inside the pyrolysis reactor, the methane-containing gas is split into hydrogen process gas and pure carbon through a pyrolysis process. The gas can also exist in a plasma state within the pyrolysis reactor. In this case, the pyrolysis reactor can also be referred to as a plasma-based pyrolysis reactor. This allows superheated hydrogen process gas, which has a temperature significantly higher than that of the methane-containing gas entering the pyrolysis reactor, to exit and be further utilized. The use of a pyrolysis reactor eliminates the need for a gas heater, particularly a gas furnace, powered by gas, thus avoiding the use of climate-damaging natural gas to heat the methane-containing gas.According to the invention, the hot hydrogen process gas exiting the pyrolysis reactor is subsequently fed to a cooling unit and cooled in a controlled manner so that it can be set to a defined temperature, in particular a target temperature, before the hydrogen process gas can be fed into the high-temperature process. The waste heat released by the hydrogen process gas in the cooling unit can, according to the invention, be used to preheat the methane-containing gas before it enters the pyrolysis reactor. This makes the process particularly economical, as the energy required by the pyrolysis reactor to heat the methane-containing gas can be reduced. During the pyrolysis of the methane-containing gas in the pyrolysis reactor, the methane-containing gas is split into hydrogen and carbon, with the carbon being able to be separated in solid form.Therefore, it is preferred that the carbon be separated and removed from the hydrogen process gas in agglomerated form. This carbon then exists in a very pure solid form – for example, as a type of carbon black (industrial soot) – and can be used accordingly. Separation can take place directly from the pyrolysis reactor or via a carbon separator in a downstream process.

[0007] The carbon can be used in subsequent processes, such as the production of tires, or stored sustainably in solid form, so that if CCU (Carbon Capture and Utilization) and / or CCS (Carbon Capture and Storage) are recognized, the hydrogen produced in the pyrolysis process can be recognized as climate-neutral.

[0008] To achieve a high level of climate friendliness for the process, the pyrolysis reactor can preferably be operated using electricity. By using electricity, the need for natural gas to heat the methane-containing gas can be reduced or even completely eliminated. In particular, electricity generated from renewable energy sources can be used, thereby reducing carbon dioxide emissions.

[0009] To cool the hot hydrogen process gas exiting the pyrolysis reactor, the cooling unit can include a heat transfer element. After exiting the pyrolysis reactor, at least a partial flow of the hot hydrogen process gas can be fed into the heat transfer element and cooled to the target temperature by releasing heat. Alternatively, the methane-containing gas can be introduced into the heat transfer element before entering the pyrolysis reactor, flow through it, and be preheated by the waste heat from the hydrogen process gas. The heat transfer element can, for example, be a heat exchanger. The hot hydrogen process gas can flow through the heat transfer element and release enough heat to cool it to a defined target temperature, at which point the hydrogen process gas can then be fed into the high-temperature process.The heat released by the hydrogen process gas can be used to preheat the methane-containing gas before it enters the pyrolysis reactor. For this purpose, the methane-containing gas can pass through the heat transfer element before entering the pyrolysis reactor and be preheated by the waste heat from the already hot hydrogen process gas exiting the pyrolysis reactor. The methane-containing gas to be preheated can, for example, be conveyed through the heat transfer element via a pipeline, with the hydrogen process gas exiting the pyrolysis reactor flowing around the pipeline. Conversely, it is also possible for the hydrogen process gas exiting the pyrolysis reactor to be conveyed through the heat transfer element via a pipeline, with the methane-containing gas to be preheated flowing around the pipeline.By preheating the methane-containing gas before it enters the pyrolysis reactor, the energy required to heat the hydrogen process gas in the pyrolysis reactor can be reduced, making the entire process more energy-efficient.

[0010] The cooling unit can further include a waste heat boiler, whereby a partial flow of the hot hydrogen process gas can be fed into the waste heat boiler and cooled there to the target temperature by releasing heat. Instead of flowing into the heat transfer element, a partial flow of the hot hydrogen process gas can pass through the waste heat boiler, releasing sufficient heat to cool the hydrogen process gas to the defined target temperature. Furthermore, it is also possible for the hydrogen process gas, having already passed through the heat transfer element, to subsequently pass through the waste heat boiler if the cooling in the heat transfer element is insufficient. The waste heat boiler can also be configured as a cooler. In this case, the waste heat from the hot hydrogen process gas is preferably not utilized.

[0011] Furthermore, the cooling unit may have a line through which cooling gas is supplied to a portion of the hot hydrogen process gas to cool it and adjust it to the target temperature. Either a portion of the hydrogen process gas can flow directly from the pyrolysis reactor through the line to be cooled with cooling gas, or a portion of the hydrogen process gas exiting the heat transfer element and / or the waste heat boiler can flow through the line for further cooling, in order to be cooled to the target temperature with cooling gas.

[0012] Oxygen can be added to the hydrogen process gas, which has been adjusted to the target temperature, before it enters the high-temperature process. This increases the carbon monoxide content in the hydrogen process gas, ensuring a particularly stable reaction in the subsequent high-temperature process. The added oxygen can convert any remaining hydrocarbons in the hydrogen process gas into carbon monoxide and hydrogen.

[0013] The problem according to the invention is further solved by means of a high-temperature process, in particular an iron ore direct reduction process, in which a hydrogen process gas, adjusted to a target temperature in a process as described above, is fed into the high-temperature process.

[0014] The object of the invention is further achieved by means of a system for supplying hydrogen process gas at a target temperature for a high-temperature process, in particular an iron ore direct reduction process, which comprises a pyrolysis reactor for the pyrolytic decomposition of methane-containing gas into hydrogen process gas and carbon, and a cooling unit for cooling the hot hydrogen process gas exiting the pyrolysis reactor to the target temperature, wherein the waste heat generated in the hydrogen process gas is used to preheat the methane-containing gas before it enters the pyrolysis reactor. In other words, the cooling unit is designed to use the thermal energy generated when cooling the hot hydrogen process gas exiting the pyrolysis reactor to preheat the methane-containing gas before it enters the pyrolysis reactor.

[0015] Regarding the possible configurations and advantages, please refer to the explanations of the process. The configuration options are entirely analogous for the system for supplying hydrogen process gas with a target temperature for a high-temperature process.

[0016] Furthermore, the problem according to the invention is solved by means of a plant arrangement which includes a high-temperature plant, in particular an iron ore direct reduction plant, and a plant for providing pre-tempered hydrogen process gas, which is designed and further developed as described above.

[0017] The invention is explained below by way of example with reference to the accompanying drawing and a preferred embodiment, wherein the features shown below can represent an aspect of the invention both individually and in combination.

[0018] The single figure shows a plant arrangement with a plant for providing hydrogen process gas for an iron ore direct reduction process and an iron ore direct reduction plant as well as a corresponding method for providing hydrogen process gas with a target temperature for a high-temperature process, which here is an iron ore direct reduction process.

[0019] The single figure shows a plant arrangement 300 with an iron ore direct reduction plant 200 as a high-temperature plant. Iron ore 10 in the form of pellets is fed into the iron ore direct reduction plant 200, where it is heated to a set temperature T by the addition of a Soll The adjusted hydrogen process gas GH2 is reduced to sponge iron DRI (Direct Reduced Iron).

[0020] To provide the hydrogen process gas GH2, a plant 100 is installed upstream of the iron ore direct reduction plant 200, in which relatively cold methane-containing gas GCH4 with an initial temperature T0 is converted into hydrogen process gas GH2, which in turn is heated to a target temperature T Soll has been brought in order to be fed into the iron ore direct reduction plant 200.

[0021] Plant 100 includes a pyrolysis reactor 110. The methane-containing gas GCH4, with an initial temperature T0, is introduced into the pyrolysis reactor 110. In addition to methane (CH4), the methane-containing gas GCH4 supplied to the pyrolysis reactor 110 may also contain hydrogen (H2), carbon monoxide (CO), higher hydrocarbons, nitrogen, and other accompanying elements.

[0022] Pyrolysis, in which the methane-containing gas GCH4 is split into hydrogen process gas GH2, which has a highly concentrated proportion of hydrogen H2, and into carbon C, results in a strong heating or superheating of the methane-containing gas GCH4 in the pyrolysis reactor 110. The carbon C can be separated and the separated carbon C can then be removed from the pyrolysis reactor 110 in a solid state.

[0023] In the case of the conversion of the methane-containing gas into the plasma state, for example by electrical stimulation, the pyrolysis reactor 110 can also be called a plasma-based pyrolysis reactor 110. The hydrogen process gas GH2 can be superheated to such an extent that it reaches a temperature T H > 1,500°C.

[0024] Pyrolysis reactor 110 is operated by means of an electric current S. Depending on the setting, more or fewer hydrocarbons are converted into hydrogen and carbon molecules, and the outlet temperature T is adjusted. H The amount of hydrogen process gas GH2 from the pyrolysis reactor 110 can be varied and adjusted accordingly.

[0025] One outlet temperature T H The superheated hydrogen process gas GH2 exits the pyrolysis reactor 110 and is fed to a cooling unit, in which the hot or superheated hydrogen process gas GH2 is cooled to a target temperature T. Soll It is cooled before being fed into the iron ore direct reduction plant 200.

[0026] The cooling unit has a heat transfer element 111. The temperature T HThe hydrogen process gas GH2, after exiting the pyrolysis reactor 110, can be fed to the heat transfer element 111 via a first line L1. In this heat transfer element 111, the hydrogen process gas GH2 can be cooled from the significantly elevated temperature T H to the defined target temperature T Soll They are cooled by the hydrogen process gas GH2 releasing heat in the heat transfer element 111.

[0027] This waste heat can be used to preheat the methane-containing gas GCH4 before it enters the pyrolysis reactor 110. The methane-containing gas GCH4, which has a temperature T0, can be introduced into the heat transfer element 111 via a line L2 and heated there to a temperature T by the waste heat of the hydrogen process gas GH2 exiting the pyrolysis reactor 110. 01 to be preheated. One temperature T 01The methane-containing gas GCH4 can then be fed to the pyrolysis reactor 110 via a line L3.

[0028] Instead of introducing the superheated hydrogen process gas GH2 into the heat transfer element 111, at least a partial flow of the superheated hydrogen process gas GH2 can also be fed via line L4 to a waste heat boiler 112 of the cooling unit. In the waste heat boiler 112, the superheated hydrogen process gas GH2 is also cooled to a defined setpoint temperature T. Soll However, in this case, the waste heat from the hydrogen process gas GH2 is not further utilized. It is also possible to feed the hydrogen process gas GH2 exiting the heat transfer element 111 to the waste heat boiler 112 to help it reach the target temperature T. Soll to cool down further.

[0029] Furthermore, it is also possible that a partial stream of the hydrogen process gas GH2 is routed via line L5 to the iron ore direct reduction reactor 200, whereby cooling gas is then added to the partial stream of the hydrogen process gas GH2 via line L7 in order to bring the hydrogen process gas GH2 to the target temperature T. Soll to cool down. Here too, it is possible that hydrogen process gas GH2 exiting the heat transfer element 111 and / or the waste heat boiler 112 flows into line L5 and is mixed with cooling gas from line L7 in order to cool the hydrogen process gas GH2 to the target temperature T. Soll to cool down further.

[0030] Before introducing the target temperature T Soll Oxygen O2 can be supplied to the hydrogen process gas GH2 in the iron ore direct reduction reactor 200.

[0031] The methane-containing gas GCH4, which has an initial temperature T0, can be composed of several components.

[0032] The process primarily uses methane-containing process gas (GCH4) derived from CNG or biogas, whereby the CNG or biogas undergoes nitrogen separation or impurity removal (310) beforehand. Since natural gas or biogas can contain impurities such as nitrogen, and these substances can accumulate during the further process, they should be removed from the natural gas or biogas beforehand.

[0033] Furthermore, hydrogen (H2) obtained from an external source can be used and added to the methane-containing gas (GCH4), thereby increasing the hydrogen content in the methane-containing gas (GCH4) even before it enters plant 100. This hydrogen (H2) could, for example, have been produced by electrolysis.

[0034] Furthermore, it is possible to discharge and process the process gas G used in the iron ore direct reduction reactor 200 via line L6, so that it can be reintroduced to the iron ore direct reduction reactor 200 as processed process gas G. The process gas G discharged from the iron ore direct reduction reactor 200 has an increased proportion of water (H2O) and carbon dioxide (CO2).

[0035] The hot process gas G discharged from the iron ore direct reduction reactor 200 can then first pass through a heat recovery unit 311. In this heat recovery unit 311, the hot process gas G discharged from the iron ore direct reduction reactor 200 can first be cooled by releasing heat. The released heat can be used for other processes. The heat recovery unit 311 can, for example, be a heat exchanger.

[0036] The cooled process gas G can then pass through a quenching unit 312. In this quenching unit 312, the process gas G is quenched or deactivated.

[0037] As the process gas G passes through the heat recovery unit 311 and the quench unit 312, it is cooled and dissolved water vapor condenses out.

[0038] Subsequently, the process gas G can be compressed in a compressor 313 and then, if necessary, fed to a CO2 scrubber 314, in which carbon dioxide (CO2) is separated from the process gas G and removed.

[0039] Cold, CO2-free process gas G emerges from this CO2 scrubber 314, which can be added to the methane-containing gas GCH4 before it is introduced into the plant 100. Reference symbol 100 plant 110 Pyrolysis reactor 111 Heat transfer element 112 waste heat boilers 200 iron ore direct reduction reactor 300 plant arrangement 310 Nitrogen separation or separation of accompanying substances 311 Heat recovery unit 312 Quench unit 313 compressors 314 CO2 scrubbers C Carbon CNG natural gas CO2 carbon dioxide DRI Iron Sponge IO Iron ore G Process gas GCH4 methane-containing gas GH2 Hydrogen process gas H2 hydrogen L1, L2, L3, L4, L5, L6, L7 line O2 Oxygen S current

Claims

[1] Method for providing hydrogen process gas (GH2) with a target temperature (T Soll ) for a high-temperature process, in particular an iron ore direct reduction process, in which methane-containing gas (GCH4) is fed to a pyrolysis reactor (110) and is split into hydrogen process gas (GH2) and carbon (C) in this pyrolysis reactor (110) by pyrolysis reaction, wherein the hot hydrogen process gas (GH2) emerging from the pyrolysis reactor (110) is fed to a cooling unit in which the hot hydrogen process gas (GH2) is cooled to the target temperature (T Soll ), whereby the resulting waste heat of the hydrogen process gas (GH2) is used to preheat the methane-containing gas (GCH4) before it enters the pyrolysis reactor (110). [2] Process according to claim 1, wherein the carbon (C) is separated and removed in agglomerated form from the hydrogen process gas (GH2). [3] Method according to claim 1 or 2, wherein the pyrolysis reactor (110) is operated by means of current (S). [4] Method according to one of claims 1 to 3, wherein the cooling unit comprises a heat transfer element (111), wherein after exiting the pyrolysis reactor (110) at least a partial flow of the hot hydrogen process gas (GH2) is supplied to the heat transfer element (111) and there heated to the desired temperature (T Soll ), wherein the methane-containing gas (GCH4) is introduced into the heat transfer element (111) before entering the pyrolysis reactor (110), flows through it and is preheated by the waste heat of the hydrogen process gas (GH2). [5] Method according to one of claims 1 to 4, wherein the cooling unit comprises a waste heat boiler (112), wherein a partial flow of the hot hydrogen process gas (GH2) is fed to the waste heat boiler (112) and there heated to the desired temperature (T Soll) is set. [6] Method according to one of claims 1 to 5, wherein the cooling unit has a line (L5, L7) via which cooling gas is supplied to a partial flow of the hot hydrogen process gas (GH2) in order to cool the hot hydrogen process gas (GH2) and to cool it to the desired temperature (T Soll ) to set. [7] Method according to one of claims 1 to 6, wherein the temperature (T Soll ) adjusted hydrogen process gas (GH2) is supplied with oxygen (O2) before entering the high-temperature process. [8] High-temperature process, in particular iron ore direct reduction process, in which in a method according to one of claims 1 to 7 a target temperature (T Soll ) adjusted hydrogen process gas (GH2) is fed to the high-temperature process. [9] Plant (100) for providing hydrogen process gas (GH2) with a target temperature (T Soll) for a high-temperature process, in particular an iron ore direct reduction process, comprising a pyrolysis reactor (110) for the pyrolytic splitting of methane-containing gas (GCH4) into hydrogen process gas (GH2) and carbon (C) and comprising a cooling unit for cooling the hot hydrogen process gas (GH2) emerging from the pyrolysis reactor (110) to the target temperature (T Soll ), whereby the resulting waste heat of the hydrogen process gas (GH2) is used to preheat the methane-containing gas (GCH4) before it enters the pyrolysis reactor (110). [10] Plant arrangement (300), comprising a high-temperature plant, in particular an iron ore direct reduction plant (200), and a plant for providing hydrogen process gas (GH2) with a target temperature (T Soll ) for a high-temperature process, which is designed according to claim 9.

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