Gas homogenization apparatus, gas homogenization method, hydrogen gas production method, hydrogen gas production equipment and its operation method, gasification and melting furnace equipment and its operation method, iron production method, heat treatment method, and iron ore production method

Abstract

To provide a gas homogenization device that can sufficiently reduce the effects of changes in the gas composition over time while suppressing an increase in power consumption. [Solution] A gas homogenization apparatus is provided, comprising: a plurality of tanks into which a first gas whose composition fluctuates over time is sequentially introduced; and a flow path through which a second gas, which is discharged from at least one of the plurality of tanks and whose fluctuation range of composition over time is reduced compared to that of the first gas, flows, wherein the first gas includes at least a portion of the off-gas discharged from an adsorption device, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

Description

Technical Field

[0001] The present disclosure relates to a gas homogenization device, a gas homogenization method, a method for producing hydrogen gas, hydrogen gas production equipment and its operation method, gasification melting furnace equipment and its operation method, an ironmaking method, a heat treatment method, and a method for producing iron ore.

Background Art

[0002] In various plants, various off-gases are generated. For example, in the pressure relief process and the regeneration process of a PSA device, an off-gas containing hydrogen gas is generated. In Patent Document 1, a technique has been proposed to suppress fluctuations in the hydrogen gas concentration in the off-gas by circulating and mixing the off-gas discharged from the PSA device between a first tank and a second tank.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] To homogenize off-gas using the method described in Patent Document 1, it is necessary to circulate a large amount of off-gas between tanks. As the amount of off-gas circulated increases, the power required to circulate the off-gas also increases. This disclosure provides a gas homogenization apparatus and a gas homogenization method that can effectively utilize the off-gas discharged from an adsorption apparatus while suppressing the increase in power. This disclosure provides a hydrogen gas production facility and an operating method thereof that can efficiently produce hydrogen gas by effectively utilizing the off-gas discharged from an adsorption apparatus. This disclosure provides a gasification and melting furnace facility and an operating method thereof that can operate efficiently by effectively utilizing the off-gas discharged from an adsorption apparatus. This disclosure provides a method for producing hydrogen gas that can effectively utilize the off-gas discharged from an adsorption apparatus. This disclosure provides a method for iron production, a heat treatment method, and a method for producing iron ore that can effectively utilize the purified gas or off-gas obtained in a hydrogen gas production facility. [Means for solving the problem]

[0005] One aspect of this disclosure provides a gas homogenization apparatus comprising: a plurality of tanks into which a first gas whose composition fluctuates over time is sequentially introduced; and a flow path through which a second gas, which is discharged from at least one of the plurality of tanks and whose composition fluctuates over time less than that of the first gas, flows, wherein the first gas includes at least a portion of the off-gas discharged from an adsorption device, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0006] The gas homogenization apparatus described above comprises multiple tanks into which a first gas, whose composition fluctuates over time, is sequentially introduced. These multiple tanks buffer the temporal fluctuations in the composition of the first gas, allowing for the output of a second gas with a reduced temporal fluctuation range in composition compared to the first gas. Such a gas homogenization apparatus reduces the impact of temporal fluctuations in the composition of the first gas and allows for the effective utilization of off-gas output from the adsorption device. Furthermore, since there is no need to circulate gas between the multiple tanks, the increase in power consumption can be suppressed.

[0007] One aspect of this disclosure is a hydrogen gas production apparatus comprising a gas homogenizer and an adsorption apparatus for purifying hydrogen gas, wherein at least a portion of the off-gas containing hydrogen gas discharged from the adsorption apparatus is introduced into the gas homogenizer as the first gas, the second gas and a third gas containing hydrogen gas and nitrogen gas and having a different composition from the first and second gases are introduced into a mixer, and the gas containing the fourth gas is introduced into the adsorption apparatus, the adsorption apparatus including a temperature swing adsorption apparatus or a pressure-temperature swing adsorption apparatus.

[0008] The above-described hydrogen gas production equipment can introduce at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device into the adsorption device using the gas homogenization device. This makes it possible to effectively utilize the hydrogen gas contained in the off-gas and produce hydrogen gas efficiently.

[0009] One aspect of this disclosure provides a gasification and melting furnace system comprising: a gas homogenizer; a melting furnace; a charging device provided above the melting furnace; and a first adsorption device for purifying nitrogen gas used in the charging device, wherein at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device is introduced into the gas homogenizer as the first gas; the second gas and a first oxygen-containing gas containing oxygen as a third gas are introduced into a mixer; a second oxygen-containing gas containing a fourth gas discharged from the mixer is introduced into the melting furnace; and the first adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0010] The above-described gasification and melting furnace equipment can introduce at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device into the gasification and melting furnace equipment using the gas homogenization device. This makes it possible to effectively utilize the oxygen gas contained in the off-gas, and the gasification and melting furnace equipment can be operated efficiently.

[0011] One aspect of this disclosure provides a gas homogenization method comprising: an introduction step of sequentially introducing a first gas whose composition fluctuates over time into a plurality of tanks; an extraction step of extracting a second gas from at least one of the plurality of tanks, the second gas having a reduced range of compositional fluctuations over time than the first gas; and a mixing step of mixing the second gas and a third gas having a different composition from the first gas and the second gas in a mixer to obtain a fourth gas, wherein the first gas includes at least a portion of the off-gas extracted from an adsorption device, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0012] The above gas homogenization method includes an introduction step in which a first gas, whose composition fluctuates over time, is sequentially introduced into multiple tanks. In such an introduction step, the fluctuations in the composition of the first gas over time are buffered in the multiple tanks. According to this gas homogenization method, the impact of fluctuations in the composition of the first gas over time is reduced, and the off-gas discharged from the adsorption device can be effectively utilized. Furthermore, since there is no need to circulate the gas between multiple tanks, the increase in power can be suppressed.

[0013] One aspect of this disclosure is a method for operating a hydrogen gas production facility comprising the gas homogenizer and the adsorption device for purifying hydrogen gas, the method comprising: a first introduction step of introducing at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device as the first gas into the gas homogenizer; a second introduction step of introducing the second gas and a third gas containing hydrogen gas and nitrogen gas and having a different composition from the first gas and the second gas into a mixer; a third introduction step of introducing the fourth gas discharged from the mixer into the adsorption device; and a purification step of obtaining hydrogen gas from the fourth gas in the adsorption device, wherein the first gas includes at least a portion of the off-gas discharged from the adsorption device, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0014] The operating method of the hydrogen gas production facility described above allows at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device to be introduced into the adsorption device using the gas homogenization device described above. This makes it possible to effectively utilize the hydrogen gas contained in the off-gas and produce hydrogen gas efficiently.

[0015] One aspect of this disclosure is a method for operating a gasification and melting furnace system comprising a gas homogenizer, a melting furnace, and a first adsorption device for purifying nitrogen gas used in the charging device of the melting furnace, the method comprising: a first introduction step of introducing at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device as the first gas into the gas homogenizer; a second introduction step of introducing the second gas and a first oxygen-containing gas containing oxygen as the third gas into a mixer; and a third introduction step of introducing the second oxygen-containing gas containing a fourth gas discharged from the mixer into the melting furnace, wherein the first gas includes at least a portion of the off-gas discharged from the adsorption device, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0016] The operating method for the gasification and melting furnace equipment described above allows at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device to be introduced into the gasification and melting furnace equipment using the gas homogenization device described above. This makes it possible to effectively utilize the oxygen gas contained in the off-gas, and the gasification and melting furnace equipment can be operated efficiently.

[0017] One aspect of this disclosure is a method for producing hydrogen gas using a hydrogen gas production facility comprising: a plurality of tanks into which a first gas containing hydrogen gas and whose composition fluctuates over time is sequentially introduced; a flow path through which a second gas, discharged from at least one of the plurality of tanks and having a reduced range of compositional fluctuations over time than the first gas, flows; a mixer that mixes the second gas with a third gas having a different composition from the first gas and the second gas to discharge a fourth gas; and an adsorption device having an adsorption tower, wherein the method for producing hydrogen gas includes a fractionation step of introducing hydrogen gas and the fourth gas containing different components from the hydrogen gas into the adsorption device, fractionating the off-gas discharged from the adsorption device to obtain a plurality of off-gas with different average concentrations of hydrogen gas, the first gas includes at least a portion of the off-gas fractionated in the fractionation step, and the adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[0018] In the hydrogen gas production method described above, the off-gas generated from the adsorption tower of the adsorption device is separated to obtain multiple off-gas with different average hydrogen gas concentrations. Therefore, each of the multiple off-gas can be used for a different purpose. Thus, while obtaining purified gas with a high hydrogen gas concentration, the off-gas can be effectively utilized according to their average hydrogen gas concentration. In this way, the off-gas discharged from the adsorption device can be effectively utilized.

[0019] One aspect of this disclosure is a steelmaking method in which the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described above are used in the steelmaking process. In this steelmaking method, the purified gas or off-gases obtained in the hydrogen gas production facility can be effectively utilized. This reduces carbon dioxide emissions.

[0020] One aspect of this disclosure provides a steelmaking method in which the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described above are introduced into a blast furnace. In this steelmaking method, the purified gas or off-gases obtained in the hydrogen gas production facility can be effectively utilized. This makes it possible to reduce carbon dioxide emissions.

[0021] One aspect of the present disclosure provides a heat treatment method of introducing the hydrogen gas and / or the plurality of off-gases obtained by the above-described hydrogen gas production method into a heating furnace. In this heat treatment method, the purified gas or off-gas obtained in the hydrogen gas production facility can be effectively utilized. Thereby, the emission of carbon dioxide can be reduced.

[0022] One aspect of the present disclosure provides an iron ore production method of introducing the hydrogen gas and / or the plurality of off-gases obtained by the above-described hydrogen gas production method directly into a direct reduction furnace. In this production method, the purified gas or off-gas obtained in the hydrogen gas production facility can be effectively utilized. Thereby, the emission of carbon dioxide can be reduced. The direct reduction furnace may use a shaft furnace or a fluidized bed.

Advantages of the Invention

[0023] The present disclosure can provide a gas homogenization device and a gas homogenization method capable of effectively utilizing the off-gas derived from an adsorption device and suppressing an increase in power. According to the present disclosure, it is possible to provide a hydrogen gas production facility and an operation method thereof capable of efficiently producing hydrogen gas by effectively utilizing the off-gas derived from an adsorption device. According to the present disclosure, it is possible to provide a gasification melting furnace facility and an operation method thereof capable of efficiently operating by effectively utilizing the off-gas derived from an adsorption device. According to the present disclosure, it is possible to provide a method for producing hydrogen gas capable of effectively utilizing the off-gas derived from an adsorption device. The present disclosure can provide a steelmaking method, a heat treatment method, and an iron ore production method capable of effectively utilizing the purified gas or off-gas obtained in a hydrogen gas production facility.

Brief Description of the Drawings

[0024] [Figure 1] It is a diagram showing an embodiment of a gas homogenization device and a hydrogen gas production facility. [Figure 2]This graph shows an example of the temporal fluctuations in the composition of off-gas generated in an adsorption device for purifying hydrogen gas. [Figure 3] This figure shows an example of an adsorption device. [Figure 4] This figure shows another example of an adsorption device. [Figure 5] This figure shows another embodiment of a gas homogenization device and a hydrogen gas production facility. [Figure 6] This graph shows an example of the temporal fluctuations in the composition of off-gas generated in an adsorption device for purifying hydrogen gas. [Figure 7] This diagram shows one embodiment of a gasification and melting furnace facility. [Figure 8] This figure shows the variation in the composition (volume ratio of oxygen gas to nitrogen gas) of the off-gas discharged from the adsorption device that generates nitrogen. [Figure 9] This is the simulation result for Example 1. (A) shows the simulation result for oxygen gas concentration, and (B) shows the simulation result for nitrogen gas concentration. [Figure 10] This is the simulation result for Comparative Example 1. (A) shows the simulation result for oxygen gas concentration, and (B) shows the simulation result for nitrogen gas concentration. [Figure 11] This is the simulation result for Example 2. [Figure 12] This is the simulation result for Comparative Example 2. [Modes for carrying out the invention]

[0025] Embodiments of this disclosure will be described below, with reference to the drawings as appropriate. However, the following embodiments are illustrative examples for illustrating this disclosure and are not intended to limit this disclosure to the following. In the description, the same reference numerals will be used for identical elements or elements having the same function, and redundant explanations will be omitted as appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships based on the orientation of the reference numerals shown in the drawings. In addition, the dimensional ratios of each element are not limited to those shown.

[0026] A gas homogenization apparatus according to one embodiment comprises a plurality of tanks into which a first gas whose composition fluctuates over time is sequentially introduced; a flow path through which a second gas, which is discharged from at least one of the plurality of tanks and whose composition fluctuates over time less than that of the first gas, flows; and a mixer that mixes the second gas with a third gas having a different composition from the first and second gases to discharge a fourth gas.

[0027] The first gas is not particularly limited as long as its composition changes over time. For example, it may be an off-gas derived from an adsorption device that includes at least one of a pressure swing adsorption device, a temperature swing adsorption device, and a pressure-temperature swing adsorption device.

[0028] A pressure swing adsorption system (PSA) is a device that uses an adsorbent to adsorb specific components contained in a mixed gas under high pressure and release them under low pressure, thereby separating or concentrating those specific components. A temperature swing adsorption system (TSA) is a device that can separate or concentrate specific components contained in a mixed gas by changing the temperature of the adsorbent. A pressure-temperature swing adsorption system (PTSA) is a technology that combines the principles of both PSA and TSA, and can separate or concentrate specific components contained in a mixed gas by changing both pressure and temperature.

[0029] The number of tanks may be two or more, three or more, or five or more. "The first gas is introduced sequentially" means that the timing of the introduction of the first gas differs. For example, if the multiple tanks include the first tank, the second tank, and the third tank, the first gas is introduced into the first tank during the first predetermined period (first period), into the second tank during the next predetermined period (second period), and into the third tank during the following predetermined period (third period). In this way, the tank into which the gas is introduced switches each time a predetermined period has elapsed. The order in which the first gas is introduced is not limited; for example, it may be introduced in the order of the first tank, the third tank, and then the second tank. The range of variation in gas composition is the difference between the minimum and maximum concentrations of a predetermined component. If the gas contains three or more components, the range of variation is determined based on the component with the largest difference between the minimum and maximum values. The period during which the first gas is introduced into each tank and the timing of switching between the tanks into which the first gas is introduced are not particularly limited, as long as the timing is such that the variation in the composition of the second gas drawn out from each tank is reduced to less than the variation in the composition of the first gas.

[0030] The composition of the first gas may fluctuate periodically. The adsorption device, along with a predetermined high-purity gas, discharges an off-gas during depressurization and regeneration of the adsorption tower. This off-gas is an example of the first gas whose composition fluctuates periodically. The period t during which the first gas is continuously introduced into each tank may be shorter or longer than the period p of the compositional fluctuation of the first gas. Alternatively, period t may equal period p. For example, the ratio of period t to period p may be between 0.1 and 1, from the viewpoint of obtaining a second gas with a sufficiently reduced range of compositional fluctuation while suppressing an excessive number of tanks. When this ratio is 1, the tank into which the first gas is introduced will be switched according to the period of the compositional fluctuation of the first gas.

[0031] The hydrogen gas production facility 200 in Figure 1 includes an adsorption device 10 for producing high-purity hydrogen gas (H2 gas) and a gas homogenization device 100 for homogenizing the off-gas (first gas) generated in the adsorption device 10, whose composition fluctuates over time. The gas homogenization device 100 includes a plurality of tanks 20, a flow path 12 for sequentially introducing the off-gas (first gas) discharged from the adsorption device 10 into a first tank 21 and a second tank 22 in the plurality of tanks 20, a flow path 52 through which the second gas discharged from the plurality of tanks 20 flows, and a mixer 30 connected to the flow path 52 for mixing the second gas and the third gas. The adsorption device 10 includes at least one of a pressure swing adsorption device (PSA), a temperature swing adsorption device (TSA), and a pressure-temperature swing adsorption device (PTSA).

[0032] Flow path 12 is connected to flow path 13, which leads off-gas out of the system. Using flow path 13, for example, a portion of the off-gas with a low hydrogen gas concentration may be released out of the system, or it may not be released. At least a portion of the off-gas containing hydrogen gas generated in the adsorption device 10 flows through flow path 12 and is introduced into the first tank 21 or the second tank 22.

[0033] The flow path 12 branches into two to introduce off-gas into the first tank 21 and the second tank 22. Valves SV1 and SV2 are provided in each of the branched flow paths. By opening and closing SV1 and SV2, the destination of the off-gas flowing through flow path 12 can be switched. In other words, SV1 and SV2 constitute a switching unit that switches the tank into which the off-gas is introduced. By operating SV1 and SV2, the off-gas flowing through flow path 12 can be alternately introduced into the first tank 21 and the second tank 22.

[0034] If the adsorption device 10 is a PTSA-type hydrogen gas purification device (H2-PTSA) that purifies hydrogen gas, in addition to high-purity (99.9% by volume or higher) hydrogen gas, an off-gas containing hydrogen gas and gases other than hydrogen gas is generated. The composition of such off-gas changes over time as the adsorption process, depressurization process, exhaust process, regeneration process, cooling process, and pressurization process are repeated in the adsorption device 10. In this case, the composition of the off-gas changes periodically with time T as one period (period p) as shown in Figure 2. Hereinafter, this off-gas in this example will be referred to as "gas 1". The concentration of hydrogen gas in gas 1 (off-gas) changes periodically between 35 and 45 by volume. The concentration of nitrogen gas in gas 1 changes periodically between 55 and 65 by volume. The range of variation in the composition of gas 1 is 10 by volume.

[0035] In Figure 1, the first gas is introduced into the first tank 21 by opening SV1 (and closing SV2) for the first cycle. Then, SV1 is closed and SV2 is opened, and the first gas is introduced into the second tank 22 for the next cycle. As a result, one cycle's worth of the first gas is introduced into both the first tank 21 and the second tank 22. Therefore, the composition of the first gas contained in the first tank 21 and the second tank 22 is homogenized. In this way, a second gas with reduced temporal fluctuations than the first gas is obtained in both the first tank 21 and the second tank 22. Furthermore, the composition of the first gas contained in the first tank 21 and the second tank 22 becomes equivalent. In this way, a second gas with reduced temporal fluctuations in composition is obtained compared to the first gas.

[0036] The first tank 21 and the second tank 22 repeatedly perform the following steps: introduction of the first gas, homogenization of the first gas (generation of the second gas), and discharge of the second gas. As described above, when SV1 is closed and SV2 is opened, and the introduction of off-gas into the second tank 22 begins, valve OV1 in the flow path 52 connected to the first tank 21 is opened. This allows the second gas generated in the first tank 21 to flow through the flow path 52. The homogenized off-gas (second gas) flows through the flow path 52 and is introduced into the mixer 30.

[0037] When the stock of the second gas in the first tank 21 becomes low, valve OV1 in the flow path 52 is closed and valve SV1 in the flow path 12 is opened. At the same time, valve SV2 in the flow path 12 is closed and valve OV2 in the flow path 52 is opened. This switches the destination of the first gas discharged from the adsorption device 10 from the second tank 22 to the first tank 21, and also switches the source of the second gas discharged to the mixer 30 from the first tank 21 to the second tank 22. In this way, the gas homogenizer 100 and the hydrogen gas production equipment 200 can be operated continuously.

[0038] The mixer 30 is connected to a flow path 52 for supplying a second gas and a flow path 53 for supplying a third gas. The third gas may contain hydrogen gas and nitrogen gas obtained by decomposing ammonia, for example, as shown in formula (1) below. The hydrogen gas content in the third gas may be 65-85% by volume, or 70-80% by volume. The nitrogen gas content in the third gas may be 15-35% by volume, or 20-30% by volume. Flow paths 52 and 53 are provided with flow control valves FV1 and FV2 for adjusting the flow rates of the second and third gases. If the composition of the second gas fluctuates, the flow rates of the second and third gases may be adjusted using FV1 and FV2 to suppress fluctuations in the composition of the fourth gas, which will be described later. 2NH3 → N2 + 3H2 ... (1)

[0039] The mixer 30 has a container body 38 composed of a cylindrical side wall, an upper plate connected to the upper end of the side wall, and a bottom plate connected to the lower end of the side wall, and baffles 31, 32, and 33 provided inside the container body 38. The baffles 31 and 33 are disc-shaped, and a ring-shaped gap is provided between the baffles 31 and 33 and the inner surface of the side wall. The baffle 32 is ring-shaped and has a circular through hole in the center. The flow paths 52 and 53 are connected to the upper plate of the container body 38, and the second and third gases are introduced from the top of the container body 38.

[0040] A zigzag flow path is formed inside the container body 38 by baffles 31, 32, and 33. The second and third gases are mixed as they flow through this flow path. In Figure 1, the mixer 30 is provided with three baffles, but it is not limited to this. From the viewpoint of thoroughly mixing and homogenizing the second and third gases in the mixer 30, the number of baffles may be five or more, seven or more, or ten or more. The mixer 30 is not limited to a shape consisting of a container body and baffles, and may, for example, be composed of a tube that forms a zigzag flow path. Various mixers such as mixers, blenders, and injectors may be used as the mixer 30.

[0041] In the mixer 30, the gas obtained by thoroughly mixing the second gas and the third gas is referred to as the "fourth gas." A flow path 44 is connected to the bottom plate of the container body 38 of the mixer 30. A compressor 40 is provided in the flow path 44. This compressor 40 allows the first gas, second gas, third gas, and fourth gas to flow through the gas homogenization device 100. Although the gas homogenization device 100 is equipped with a power source for circulating the gas in this way, it does not need to circulate the first gas through multiple tanks 20, thus suppressing the increase in power required for homogenization. The fourth gas generated in the mixer 30 is led out of the mixer 30 into the flow path 44.

[0042] The fourth gas includes the third gas, which contains hydrogen and nitrogen gas obtained by decomposing ammonia, and the second gas, which is a homogenized version of the first gas (off-gas) discharged from the adsorption device 10. As shown in Figure 2, this first gas contains hydrogen gas, and its concentration fluctuates periodically. However, in the gas homogenization device 100, the second gas, which has reduced periodic fluctuations, is produced in multiple tanks 20, and the third gas and the second gas with reduced periodic fluctuations are mixed in the mixer 30. As a result, the temporal fluctuations in composition are sufficiently suppressed, and a sufficiently homogenized fourth gas can be obtained.

[0043] The fourth gas flows through the flow path 44 and is introduced into the adsorption device 10. The fourth gas contains hydrogen gas that was originally contained in the first gas. Therefore, the hydrogen gas production facility 200 can efficiently produce hydrogen gas by effectively utilizing the off-gas. The fourth gas, in which the temporal composition fluctuations are sufficiently suppressed, is introduced into the hydrogen gas production facility 200. Therefore, the adsorption device 10 can be operated sufficiently stably.

[0044] As shown in Figure 3, the adsorption apparatus 10 has four adsorption towers (first adsorption tower 10A, second adsorption tower 10B, third adsorption tower 10C, and fourth adsorption tower 10D). The first adsorption tower 10A, second adsorption tower 10B, third adsorption tower 10C, and fourth adsorption tower 10D contain adsorbents that adsorb gases other than hydrogen gas (such as nitrogen gas). Each adsorption tower may purify hydrogen gas by repeatedly performing the following steps: adsorption, depressurization, exhaust, regeneration, cooling, and pressurization.

[0045] The adsorption process is a process in which gases other than hydrogen gas contained in the fourth gas (raw material gas) are adsorbed onto the adsorbent in the adsorption tower under low temperature and high pressure, and hydrogen gas is recovered. The depressurization process is a process in which the inside of the adsorption tower is depressurized after the adsorption process to lower the pressure inside the adsorption tower to a level lower than that of the adsorption process, and the hydrogen gas and fourth gas remaining inside the adsorption tower are discharged. The off-gas generated at this time contains the hydrogen gas and fourth gas remaining inside the adsorption tower. The exhaust process is a process in which the fourth gas and hydrogen gas remaining inside the adsorption tower are discharged by opening to atmospheric pressure or by using a vacuum pump or the like. In the exhaust process, the pressure inside the adsorption tower is lowered even further than in the depressurization process, and the gas remaining inside the adsorption tower is discharged. The regeneration process is a process in which impurities adsorbed on the adsorbent are released and discharged by heating the adsorbent. The cooling process is a process in which the adsorbent is cooled to a low temperature to restore its adsorption capacity. The pressurization process is a process in which hydrogen gas is introduced into the adsorption tower after the cooling process is completed, and the inside of the adsorption tower is pressurized.

[0046] Figure 3 shows the state in which the first adsorption tower 10A is performing the adsorption process, the second adsorption tower 10B is performing the depressurization and exhaust processes, the third adsorption tower 10C is performing the regeneration process, and the fourth adsorption tower 10D is performing the cooling and pressurization processes. High-purity hydrogen gas is obtained from the first adsorption tower 10A. On the other hand, off-gas containing hydrogen gas and other gases is generated from the second adsorption tower 10B and the third adsorption tower 10C. All of the off-gas generated in this way may be introduced into multiple tanks 20 via the flow path 12.

[0047] In the adsorption apparatus 10 shown in Figure 4, the flow paths connected to the lower parts of the second adsorption tower 10B, which performs the depressurization and exhaust processes, and the third adsorption tower 10C, which performs the regeneration process, are branched into multiple paths. Specifically, they branch into a flow path 12 connected to the multiple tanks 20 shown in Figure 1, and a flow path 14 that is not connected to the multiple tanks 20 shown in Figure 1, but is connected to equipment outside the system. The hydrogen gas concentration of the off-gas (first off-gas) obtained in the depressurization and regeneration processes is, for example, 40 volume percent or more on average between the depressurization and regeneration processes, which is higher than the average hydrogen gas concentration of the off-gas (second off-gas) obtained in the exhaust process.

[0048] Of the off-gas discharged from the adsorption device 10, only the high-quality off-gas (first off-gas) with a high concentration of hydrogen gas may be introduced as the first gas via the flow path 12 into multiple tanks 20. This reduces the concentration of gas components other than hydrogen gas in the fourth gas, thereby reducing the load on the adsorption device 10. The low-quality off-gas (second off-gas) with a lower concentration of hydrogen gas than the high-quality off-gas may be circulated through the flow path 14 and used, for example, as fuel in a combustion facility. It is not essential to introduce the entire amount of high-quality off-gas into multiple tanks 20, and a portion of the high-quality off-gas may be used for other purposes. Since this high-quality off-gas has a higher calorific value and less variation in composition than the low-quality off-gas, it may be used as fuel for a generator. By separating the off-gas into multiple types in this way, energy can be used more efficiently.

[0049] Although the explanation used a PTSA-type hydrogen gas purification system as an example, in the case of TSA-type and PSA-type gas purification systems, off-gas is discharged from the adsorption unit 10 in the same way as in the PTSA-type system. By separating the discharged off-gas according to the hydrogen gas concentration, high-quality off-gas and low-quality off-gas can be obtained.

[0050] A hydrogen gas production method may be carried out using an adsorption apparatus 10 equipped with multiple adsorption towers as shown in Figure 4. In this hydrogen gas production method, high-purity hydrogen gas can be obtained as purified gas, as well as high-quality off-gas (first off-gas) and low-quality off-gas (second off-gas). For this reason, it can also be called a hydrogen gas production method. At least one selected from the group consisting of the purified gas (hydrogen gas), high-quality off-gas, and low-quality off-gas obtained in this way may be introduced into a blast furnace or used in the steelmaking process. This can reduce the amount of carbon dioxide emitted in connection with steel production. At least one selected from the group consisting of the purified gas (hydrogen gas), high-quality off-gas, and low-quality off-gas may be introduced into a heating furnace and used for heat treatment, or it may be introduced directly into a reduction furnace and used for the production of iron ore. This can reduce the amount of carbon dioxide emitted.

[0051] The hydrogen gas concentrations in high-quality and low-quality off-gas may fluctuate over time. The average hydrogen gas concentration in high-quality off-gas is higher than that of low-quality off-gas. The average hydrogen gas concentration in high-quality off-gas may be 40% by volume or higher, or 45% by volume or higher.

[0052] The hydrogen gas production facility 210 in Figure 5 includes an adsorption device 10 for purifying hydrogen gas and a gas homogenization device 110 for homogenizing the off-gas (first gas) generated in the adsorption device 10, whose composition fluctuates over time. The gas homogenization device 110 includes a plurality of tanks 20A, a flow path 12 for sequentially introducing the off-gas (first gas) discharged from the adsorption device 10 into the plurality of tanks 20A, flow paths 51, 52, and 54 through which the second gas discharged from the plurality of tanks 20A flows, a flow path 53 through which the third gas flows, and a mixer 30 for mixing the second gas and the third gas.

[0053] The hydrogen gas production facility 210 in Figure 5 differs from the hydrogen gas production facility 200 in Figure 1 in the number of tanks 20A into which the first gas is introduced, and the related ancillary equipment. Other configurations may be the same as those of the hydrogen gas production facility 200 in Figure 1. Here, we will explain the differences from the hydrogen gas production facility 200 in Figure 1, focusing on the differences between the two.

[0054] The flow path 12 branches into seven channels to introduce off-gas to the first tank 21, the second tank 22, the third tank 23, the fourth tank 24, the fifth tank 25, the sixth tank 26, and the seventh tank 27 (hereinafter collectively referred to as "tank group 21-27"). Each branched flow path is equipped with valves SV1, SV2, SV3, SV4, SV5, SV6, and SV7 (hereinafter collectively referred to as "SV1-SV7"). By opening and closing SV1-SV7, the destination of the first gas flowing through the flow path 12 can be switched. In other words, SV1-SV7 constitute a switching unit that switches which tank the first gas is introduced into. By operating SV1-SV7, the first gas can be introduced into each tank of tank group 21-27 at different timings. The first gas may be introduced into each tank of tank group 21-27 sequentially, or it may be introduced sequentially into groups of two or three tanks of tank group 21-27.

[0055] Tank groups 21 to 27 are connected to at least one flow path selected from a group consisting of flow paths 51 and 52. Each branch pipe connecting flow path 51 to the first tank 21, the second tank 22, the third tank 23, the fourth tank 24, and the fifth tank 25 is equipped with valves OV1A, OV2A, OV3A, OV4A, and OV5A, respectively. By operating these valves, the discharge of the second gas from the first tank 21, the second tank 22, the third tank 23, the fourth tank 24, and the fifth tank 25 to flow path 51 can be started or stopped.

[0056] Each branch pipe connecting the flow path 52 to the second tank 22, third tank 23, fourth tank 24, fifth tank 25, sixth tank 26, and seventh tank 27 is equipped with valves OV2B, OV3B, OV4B, OV5B, OV6B, and OV7B, respectively. By operating these valves, the discharge of the second gas from the second tank 22, third tank 23, fourth tank 24, fifth tank 25, sixth tank 26, and seventh tank 27 to the flow path 52 can be started or stopped. In other words, the source tank from which the second gas is discharged can be switched.

[0057] Flow paths 51 and 52 are connected to a premixer 30A (second mixer). The premixer 30A has a container body 39 composed of a cylindrical side wall, an upper plate connected to the upper end of the side wall, and a bottom plate connected to the lower end of the side wall, and baffles 35, 36, and 37 provided inside the container body 39. The baffles 35 and 37 are disc-shaped, and a ring-shaped gap is provided between the baffles 35 and 37 and the inner surface of the side wall. The baffle 36 is ring-shaped and has a circular through-hole in the center. Flow paths 51 and 52 are connected to the upper plate of the container body 39, and the second gas that has flowed through flow paths 51 and 52 is introduced from the top of the container body 39.

[0058] A zigzag flow path is formed inside the container body 39 by baffles 35, 36, and 37. The second gases supplied from different tanks are mixed as they flow through these flow paths. This allows the second gases to be sufficiently homogenized. In Figure 5, the pre-mixer 30A is provided with three baffles, but it is not limited to this. From the viewpoint of sufficiently mixing and homogenizing the second gases in the pre-mixer 30A, the number of baffles may be five or more, seven or more, or ten or more. The pre-mixer 30A is not limited to a shape consisting of a container body and baffles, similar to the mixer 30, but may be composed of, for example, a tube that forms a zigzag flow path. Various mixers such as mixers, blenders, and injectors may be used as the pre-mixer 30A.

[0059] If the composition of the first gas fluctuates as shown in Figure 2, the first gas may be introduced sequentially into multiple tanks within one cycle (period p) of the composition fluctuation of the first gas. Figure 6 shows the composition fluctuation of the first gas over one cycle. In Figure 6, the horizontal axis represents time, and the vertical axis represents the volume ratio of nitrogen gas. In Figure 6, one cycle is divided equally into six time periods: I, II, III, IV, V, and VI. The tank into which the first gas is introduced may be switched for each of these time periods. Tables 1 and 2 show examples of tank switching.

[0060] [Table 1]

[0061] [Table 2]

[0062] Tables 1 and 2 show the state of tank groups 21-27 in time zones I-VI of cycles 1-9. One cycle corresponds to one period. In each cycle, the composition of the first gas (off-gas) changes as shown in Figure 6. Although Tables 1 and 2 show cycles 1-9, the number of cycles is not limited, and the same operations as up to cycle 9 may be repeated in cycle 10 and beyond.

[0063] In Tables 1 and 2, "Introducing" indicates that the first gas is introduced into each tank, "Standby" indicates that the tanks are filled with the second gas, and "Detaching" indicates that the second gas is detached from each tank into either channel 51 or channel 52. "Detaching" means that all of the second gas in one tank is detached in one time period, while "1 / 2 Detaching" means that all of the second gas in two tanks is detached over two time periods. Therefore, the amount of second gas detached from each tank per unit time is half that of "Detaching" in "1 / 2 Detaching". "↓" indicates that the same state as the previous time period continues, and "-" indicates that the tank is substantially empty after the second gas has been detached.

[0064] As shown in Tables 1 and 2, the first gas discharged from the adsorption device 10 during time zone I in each cycle is introduced into the first tank 21. The first gas introduced into the first tank 21 remains and homogenizes during time zones II to V to become the second gas, which is then discharged from the first tank 21 during time zone VI. In addition, the first gas generated during time zone IV in each cycle is introduced into the fourth tank 24, fifth tank 25, sixth tank 26, or seventh tank 27. It remains in these tanks for a while and homogenizes to become the second gas, which is then discharged from each tank during one of the time zones. Since the first gas generated during time zones I and IV has a composition that is roughly close to the average composition of the first gas generated in one cycle, even if the second gas is discharged independently, the temporal fluctuation of the composition of the second gas can be sufficiently suppressed.

[0065] In each cycle, the first gas generated in time zone III is introduced into the second tank 22, the third tank 23, the fourth tank 24, or the fifth tank 25. In each cycle, the first gas generated in time zone V is introduced into the second tank 22, the third tank 23, or the fifth tank 25. The first gas introduced into each tank remains there for a while and becomes homogenized to become the second gas. The second gas introduced into each tank in time zone III and the second gas introduced into each tank in time zone V are led out into flow path 51 or flow path 52 at the same time. These are merged and mixed in the premixer 30A. This yields a second gas with a composition that is roughly close to the average composition of the first gas generated in one cycle.

[0066] In each cycle, the first gas generated in time zone II is introduced into the second tank 22, the fourth tank 24, the sixth tank 26, or the seventh tank 27. In each cycle, the first gas generated in time zone VI is introduced into the third tank 23, the fourth tank 24, the fifth tank 25, or the sixth tank 26. The first gas introduced into each tank remains there for a while and becomes homogenized to become the second gas. The second gas generated and homogenized in time zone II and the second gas generated and homogenized in time zone VI are led out to flow path 51 or flow path 52 at the same time. These are merged and mixed in the premixer 30A. This yields a second gas with a composition that is roughly close to the average composition of the first gas generated in one cycle.

[0067] In this way, a second gas with reduced temporal compositional fluctuations is obtained. This second gas flows through the flow path 54 and is introduced into the mixer 30. The components from the mixer 30 onward may be the same as those in the embodiment shown in Figure 1. In this embodiment, the number of tanks into which the first gas is introduced per cycle of compositional fluctuation of the first gas is 6, while the total number of tanks 20A is 7. By making the total number of tanks greater than the number of tanks into which the first gas is introduced per cycle, it is possible to stably obtain second and fourth gases with sufficiently suppressed compositional fluctuations.

[0068] The gas homogenization apparatus described herein may be included in equipment other than hydrogen gas production equipment. For example, it may be included in a gasification and melting furnace facility for processing waste.

[0069] The gasification melting furnace equipment 300 in Figure 7 comprises a carbon bed type melting furnace 70, a charging device 60 having a double seal mechanism provided at the top of the melting furnace 70, a gas homogenization device 120, and a first adsorption device 10a for preparing nitrogen gas used in the charging device 60. The melting furnace 70 has a shaft section 72, a bell section 74 provided at the lower end of the shaft section 72, and a furnace bottom section 76 provided at the lower part of the bell section 74. From the shaft section 72 to the furnace bottom section 76, upper tuyeres 75 for the pyrolysis zone and lower tuyeres 77 for the combustion melting zone are provided in order from top to bottom. The upper tuyeres 75 and lower tuyeres 77 may each be provided in multiple stages.

[0070] In the charging device 60, air mixed in the waste, charcoal, and auxiliary materials is removed by nitrogen gas before being charged into the melting furnace 70. Examples of waste include general waste, industrial waste, processed materials such as incinerated ash obtained by drying, incineration, or crushing these materials, and landfill waste containing soil and sand that has been excavated after being landfilled. The auxiliary materials may include the basicity adjusting agent mentioned above. In addition to the basicity adjusting agent, the auxiliary materials may include at least one selected from iron ore, magnesia, periclase, kudolithite, and jamonite. By using such auxiliary materials, the waste 78 can be sufficiently melted inside the melting furnace 70. As charcoal, coal, coke or molded charcoal, woody biomass, etc., can be used.

[0071] Oxygen-enriched air is supplied from the lower tuyere 77, and air is supplied as a combustion-supporting gas from the upper tuyere 75. The carbon material charged into the melting furnace 70 is burned by the oxygen-enriched air supplied from the lower tuyere 77 and functions as a heat source. The waste 78, including auxiliary materials, charged into the melting furnace 70 is heated to, for example, over 1600°C by the combustion of the carbon material, and becomes a pyrolysis residue 73. The pyrolysis residue 73 is burned mainly by air supplied from the upper tuyere 75.

[0072] The combustible components in the waste 78, along with the plastics and biomass contained in the molded body of the basicity adjuster, are gasified and rise within the melting furnace 70, then introduced into the combustion chamber via the exhaust gas pipe 62. Meanwhile, the ash becomes molten slag via the pyrolysis residue 73. The lime and silica sources contained in the molded body of the basicity adjuster function as basicity adjusters for the molten slag. The molten slag, with its basicity adjusted, flows down the carbon material-filled bed 71 at the bottom of the furnace 76 and is discharged from the outlet 79.

[0073] The pyrolysis gas generated in the melting furnace 70 rises up the shaft section 72 and is introduced into the combustion chamber through the exhaust gas pipe 62 connected to the lower part of the charging device 60. The combustion exhaust gas is burned as a combustible gas and then the waste heat is recovered in the boiler. After that, the exhaust gas may be cooled in a cooling tower, then pass through a dust collector and a catalytic reaction tower before being discharged from the chimney.

[0074] The first adsorption device 10a may be a PTSA-type nitrogen gas purification device (N2-PTSA) for purifying nitrogen gas. The first adsorption device 10a, for example, obtains high-purity nitrogen gas from air and discharges an off-gas containing nitrogen gas and oxygen gas. As shown in Figure 3, the first adsorption device 10a also has a plurality (e.g., 2 to 4) of adsorption towers, each containing an adsorbent for adsorbing gases other than nitrogen gas (such as oxygen gas). Each adsorption tower may repeat the processes of adsorption, depressurization, exhaust, regeneration, cooling, and pressurization. The first adsorption device 10a may be a PSA-type nitrogen gas purification device (N2-PSA) for purifying nitrogen gas. In this case, each adsorption tower may repeat the processes of adsorption, depressurization, exhaust, regeneration, cooling, and pressurization.

[0075] The first adsorption apparatus 10a may be a TSA-type nitrogen gas purification apparatus (N2-TSA) for purifying nitrogen gas. In this case, each adsorption tower in the first adsorption apparatus 10a may repeatedly perform an adsorption step to obtain high-purity nitrogen gas by adsorbing gases other than nitrogen gas (such as oxygen gas) at low temperatures, a regeneration step to regenerate the adsorbent by heating the adsorbent that has adsorbed gases other than nitrogen gas to release the adsorbed gas, and a cooling step to cool the adsorbent to restore its adsorption capacity.

[0076] The nitrogen gas obtained in the first adsorption device 10a may be used in the charging device 60 to remove air mixed in the waste, charcoal, and auxiliary materials, and to charge the device. The off-gas generated in the depressurization process, exhaust process, and regeneration process, etc., contains oxygen gas. Hereinafter, in this example, the off-gas containing oxygen gas will be referred to as the "first gas." The first gas flows through the flow path 12 and is sequentially introduced into each of the multiple tanks 20, similar to the embodiment shown in Figure 1. The first gas introduced into the first tank 21 and the second tank remains and becomes homogenized. In this way, a second gas with a reduced range of temporal compositional fluctuations than the first gas is obtained in the first tank 21 and the second tank. Furthermore, the composition of the second gas contained in the first tank 21 and the second tank 22 becomes equivalent.

[0077] Mixer 30 is connected to a flow path 52 for supplying a second gas and a flow path 53 for supplying a third gas. The third gas may be high-purity oxygen gas obtained from the second adsorption device 80. The second adsorption device 80 may be a PSA type oxygen gas purification device (O2-PSA) that purifies oxygen gas from air. The second adsorption device 80 may be a PTSA type oxygen gas purification device (O2-PTSA), a TSA type oxygen gas purification device (O2-TSA), or a PSA type oxygen gas purification device (O2-TSA) that purifies oxygen gas from air. As shown in Figure 3, the configuration of the PTSA type oxygen gas purification device, TSA type oxygen gas purification device, and PSA type oxygen gas purification device also has multiple (for example, 2 to 4) adsorption towers, each containing an adsorbent that adsorbs gases other than oxygen gas (such as nitrogen gas).

[0078] In the case of a PTSA-type oxygen gas purification system (O2-PTSA), each adsorption tower may repeat the following steps: adsorption, depressurization, exhaust, regeneration, cooling, and pressurization. In the case of a TSA-type oxygen gas purification system (O2-TSA), each adsorption tower may repeat the following steps: adsorption, regeneration, and cooling. In the case of a PSA-type oxygen gas purification system, each adsorption, depressurization, exhaust, regeneration, and pressurization may repeat.

[0079] In the mixer 30, the oxygen gas concentration of the oxygen-enriched air (fourth gas) obtained by mixing the second gas and the third gas may be, for example, 30 to 80 volume percent, or 40 to 70 volume percent. The oxygen-enriched air generated in the mixer 30 may be supplied to the melting furnace 70 from the lower tuyere 77 after being mixed with air as needed. By using the first gas generated in the first adsorption device 10a to adjust the oxygen-enriched air, the load on the second adsorption device 80 can be reduced. Furthermore, since the oxygen-enriched air obtained in the mixer 30 has sufficiently suppressed compositional fluctuations over time, the melting furnace 70 can be operated in a sufficiently stable manner.

[0080] A gas homogenization method according to one embodiment includes an introduction step of sequentially introducing a first gas, whose composition fluctuates over time, into a plurality of tanks 20; an extraction step of extracting a second gas, whose composition fluctuates less over time than the first gas, from at least one of the plurality of tanks 20; and a mixing step of mixing the second gas and a third gas having a different composition from the first and second gases in a mixer to obtain a fourth gas. This gas homogenization method may be performed in the gas homogenization apparatus 100 of the hydrogen gas production facility 200 shown in Figure 1, the gas homogenization apparatus 110 of the hydrogen gas production facility 210 shown in Figure 5, the gas homogenization apparatus 120 of the gasification melting furnace facility 300 shown in Figure 7, or in other facilities. The above descriptions of each apparatus and facility also apply to the gas homogenization method.

[0081] An operating method for a hydrogen gas production facility according to one embodiment is an operating method for a hydrogen gas production facility 200 (210) comprising a gas homogenizer 100 (110) and an adsorption device 10, as shown in Figure 1 (Figure 5), comprising: a first introduction step of introducing at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device 10 as a first gas into the gas homogenizer 100; a second introduction step of introducing a third gas containing hydrogen gas and nitrogen gas into a mixer 30; a third introduction step of introducing a fourth gas containing hydrogen gas and nitrogen gas into the adsorption device 10; and a purification step of obtaining hydrogen gas from the fourth gas in the adsorption device 10.

[0082] The operation method for this hydrogen gas production equipment may be carried out in the hydrogen gas production equipment 200 shown in Figure 1, the hydrogen gas production equipment 210 shown in Figure 5, or in a hydrogen gas production equipment other than those shown. The description of hydrogen gas production equipment 200 and 210 also applies to the operation method of the hydrogen gas production equipment.

[0083] One embodiment of the hydrogen gas production method may be carried out using the adsorption apparatus 10 shown in Figure 4. The above-described explanation of the hydrogen gas production equipment 200 and its operating method also applies to the hydrogen gas production method. If the adsorption device 10 is a PTSA, the hydrogen gas production method involves an adsorption step in which hydrogen gas and a raw material gas (fourth gas) containing a different component (e.g., nitrogen gas) are introduced into the adsorption tower, and the different component is adsorbed onto the adsorbent of the adsorption tower 10A (10B, 10C, 10D) to obtain purified gas with a higher hydrogen gas concentration than the raw material gas; a depressurization step in which the introduction of raw material gas into the adsorption tower 10A (10B, 10C, 10D) is stopped, the pressure inside the adsorption tower 10A (10B, 10C, 10D) is lowered compared to the adsorption step, and the gas remaining inside the adsorption tower 10A (10B, 10C, 10D) is discharged; and a depressurization step in which the pressure inside the adsorption tower 10A (10B, 10C, 10D) is further lowered compared to the depressurization step, and the gas remaining inside the adsorption tower 10A (10B, 10C, 10D) is discharged. The system includes an exhaust process for discharging any remaining gas inside the adsorption tower 10A (10B, 10C, 10D), a regeneration process for raising the temperature inside the adsorption tower 10A (10B, 10C, 10D) to release and discharge foreign components adsorbed by the adsorbent, a process for lowering the temperature inside the adsorption tower 10A (10B, 10C, 10D) to restore the adsorption capacity of the adsorbent, a pressurization process for pressurizing the inside of the adsorption tower by introducing raw material gas into the adsorption tower 10A (10B, 10C, 10D), and a separation process for separating a first off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the depressurization process and the regeneration process, and a second off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the exhaust process, which has a lower average concentration of hydrogen gas than the first off-gas. In the separation process, the first off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the depressurization process may be separated from the second off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the regeneration process and the exhaust process, which has a lower average concentration of hydrogen gas than the first off-gas.

[0084] The raw material gas is not limited to the fourth gas; various gases, including hydrogen gas, can be used. By repeatedly performing a series of processes in each adsorption tower, high-purity hydrogen gas can be continuously produced while effectively utilizing the off-gas. The number of adsorption towers is not limited to four. In the fractionation process, the off-gas obtained in the depressurization process, exhaust process, and regeneration process may be separated into three off-gas with different average concentrations of hydrogen gas, or the off-gas obtained in the depressurization process may be separated into the off-gas obtained in the exhaust process and the off-gas obtained in the regeneration process. In this way, it is sufficient to obtain multiple off-gas with different average concentrations of hydrogen gas.

[0085] If the adsorption device is TSA, the hydrogen gas production method involves an adsorption step in which hydrogen gas and a raw material gas containing a different component (e.g., nitrogen gas) are introduced into the adsorption tower, and the different component is adsorbed onto the adsorbent in the adsorption tower 10A (10B, 10C, 10D) to obtain purified gas with a higher hydrogen gas concentration than the raw material gas, and then stopping the introduction of the raw material gas into the adsorption tower 10A (10B, 10C, 10D), raising the temperature inside the adsorption tower 10A (10B, 10C, 10D) compared to the adsorption step, and then... The system includes a regeneration step of discharging foreign components adsorbed on the adsorbent along with the gas remaining in the adsorption tower 10A (10B, 10C, 10D), a cooling step of lowering the temperature inside the adsorption tower 10A (10B, 10C, 10D), and a separation step of separating a first off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the first half of the regeneration step, and a second off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the latter half of the regeneration step, which has a lower average concentration of hydrogen gas than the first off-gas.

[0086] If the adsorption device 10 is a PSA, the hydrogen gas production method is as follows: an adsorption step in which hydrogen gas and a raw material gas (fourth gas) containing a different component (e.g., nitrogen gas) are introduced into the adsorption tower, and the different component is adsorbed onto the adsorbent of the adsorption tower 10A (10B, 10C, 10D) to obtain purified gas with a higher hydrogen gas concentration than the raw material gas; a depressurization step in which the introduction of raw material gas into the adsorption tower 10A (10B, 10C, 10D) is stopped, the pressure inside the adsorption tower 10A (10B, 10C, 10D) is lowered compared to the adsorption step, and the gas remaining inside the adsorption tower 10A (10B, 10C, 10D) is discharged; and a depressurization step in which the pressure inside the adsorption tower 10A (10B, 10C, 10D) is further lowered compared to the depressurization step, and the gas inside the adsorption tower 10A (10B, 10C, 10D) The system includes an exhaust process for discharging the remaining gas, a regeneration process for further reducing the pressure inside the adsorption tower 10A (10B, 10C, 10D) compared to the exhaust process, and for discharging the remaining gas inside the adsorption tower 10A (10B, 10C, 10D) along with foreign components adsorbed on the adsorbent, a pressurization process for pressurizing the inside of the adsorption tower by introducing raw material gas into the adsorption tower 10A (10B, 10C, 10D) following the regeneration process, and a separation process for separating a first off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the depressurization process and the regeneration process, and a second off-gas discharged from the adsorption tower 10A (10B, 10C, 10D) in the exhaust process, which has a lower average concentration of hydrogen gas than the first off-gas.

[0087] Regardless of whether the adsorption device 10 is of the PTSA, TSA, or PSA type, the raw material gas is not limited to the fourth gas, and various gases including hydrogen gas can be used. By repeatedly performing a series of processes in each adsorption tower, high-purity hydrogen gas can be continuously produced while effectively utilizing the off-gas. The number of adsorption towers is not limited to four. In the fractionation process, the off-gas obtained in each process of the adsorption device 10 may be separated into multiple off-gases with different average concentrations of hydrogen gas. This makes it possible to obtain multiple off-gases with different average concentrations of hydrogen gas.

[0088] An operating method for a gasification and melting furnace system according to one embodiment is an operating method for a gasification and melting furnace system 300, which includes a gas homogenizer 120 shown in Figure 7, a melting furnace 70, and a first adsorption device 10a for purifying nitrogen gas used in the charging device 60 of the melting furnace 70, comprising: a first introduction step of introducing at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device 10a as the first gas into the gas homogenizer 120; a second introduction step of introducing the first oxygen-containing gas containing oxygen as the third gas into the mixer 30; and a third introduction step of introducing the second oxygen-containing gas containing the fourth gas into the melting furnace 70. The third gas (first oxygen-containing gas) may be a gas obtained in the second adsorption device 80. The second oxygen-containing gas may be oxygen-enriched air obtained by mixing the third gas and air.

[0089] The operation method for this gasification and melting furnace equipment may be carried out in the gasification and melting furnace equipment 300 shown in Figure 7, or in a different gasification and melting furnace equipment. The description of the gasification and melting furnace equipment 300 also applies to the operation method of the gasification and melting furnace equipment.

[0090] Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the adsorption device is not limited to one, and the gas homogenization device may include two or more adsorption devices. In this case, the types of gas homogenization devices may be the same or different. The first off-gases (second off-gases) obtained by separating the off-gases discharged from each adsorption device may be combined and used, or they may be used individually. The present disclosure includes the following embodiments.

[0091] [1] Multiple tanks into which a first gas whose composition changes over time is sequentially introduced, The system comprises a flow path through which a second gas, which is drawn from at least one of the aforementioned tanks and whose composition fluctuates less over time than that of the first gas, flows, The first gas includes at least a portion of the off-gas discharged from the adsorption device. The adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device, and is a gas homogenization device. [2] The gas homogenization apparatus according to [1], wherein the composition of the first gas fluctuates periodically. [3] The gas homogenization apparatus according to [1] or [2], further comprising a mixer that mixes the second gas with a third gas having a different composition from the first gas and the second gas to produce a fourth gas. [4] The flow path of the off-gas discharged from the adsorption tower of the adsorption apparatus is divided into multiple branches, A gas homogenization apparatus according to any one of [1] to [3], wherein the off-gas is separated into a plurality of off-gas having different average concentrations of hydrogen, and the separated off-gas are sequentially introduced into the plurality of tanks as the first gas. [5] The system includes a switching unit that switches which tank the first gas is introduced into so that the first gas is introduced into each of the multiple tanks in sequence. The gas homogenization apparatus according to any one of [1] to [4], wherein the switching unit switches the tank according to the period of variation in the composition of the first gas. [6] The system includes a switching unit that switches which tank the first gas is introduced into so that the first gas is introduced into each of the multiple tanks in sequence. The gas homogenization apparatus according to any one of [1] to [5], wherein the switching unit switches the tank at a period shorter than the period of compositional fluctuation of the first gas. [7] The gas homogenization apparatus according to any one of [1] to [6], wherein the total number of the plurality of tanks is greater than the number of tanks into which the first gas is introduced per cycle of the composition variation of the first gas. [8] A hydrogen gas production facility comprising a gas homogenizer described in any one of [1] to [7] above, and an adsorption device for purifying hydrogen gas, At least a portion of the off-gas containing hydrogen gas discharged from the adsorption device is introduced into the gas homogenization device as the first gas. The second gas and a third gas containing hydrogen gas and nitrogen gas, having a different composition from the first gas and the second gas, are introduced into the mixer. The gas containing the fourth gas, which is discharged from the mixer, is introduced into the adsorption device. The adsorption apparatus includes at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus, and is a hydrogen gas production facility. [9] The hydrogen gas production apparatus according to [8], wherein the average concentration of hydrogen gas in the off-gas introduced into the gas homogenizer as the first gas is 40% by volume or more.

[10] A gasification melting furnace facility comprising a gas homogenization device described in any one of [1] to [9] above, a melting furnace, a charging device provided above the melting furnace, and a first adsorption device for purifying nitrogen gas used in the charging device, At least a portion of the off-gas containing oxygen gas discharged from the first adsorption device is introduced into the gas homogenization device as the first gas. The second gas and a first oxygen-containing gas containing oxygen as a third gas are introduced into the mixer. The second oxygen-containing gas, including the fourth gas discharged from the mixer, is introduced into the melting furnace. The first adsorption device is a gasification melting furnace facility that includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[11] The gasification melting furnace apparatus according to

[10] , further comprising a second adsorption device for obtaining the first oxygen-containing gas having a higher oxygen gas concentration than the air as the third gas from air.

[12] An introduction process in which a first gas whose composition changes over time is sequentially introduced into multiple tanks, A discharge step of dischargeing a second gas from at least one of the plurality of tanks, the second gas having a reduced range of temporal compositional fluctuations than the first gas, The process includes a mixing step of mixing the second gas and a third gas having a different composition from the first and second gases in a mixer to obtain a fourth gas, The first gas includes at least a portion of the off-gas discharged from the adsorption device. A gas homogenization method comprising an adsorption apparatus including at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus.

[13] The flow path leading out from the adsorption tower of the adsorption apparatus is branched into multiple paths, and the apparatus has a separation process for separating the off-gas led out from the adsorption tower into multiple types, The gas homogenization method according to

[12] , wherein a portion of the separated off-gas is sequentially introduced into the plurality of tanks as the first gas.

[14] A method for operating a hydrogen gas production facility comprising a gas homogenizer described in any one of [1] to [9] above, and an adsorption device for purifying hydrogen gas, A first introduction step involves introducing at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device as the first gas into the gas homogenization device, A second introduction step involves introducing the second gas and a third gas, which includes hydrogen gas and nitrogen gas and has a different composition from the first gas and the second gas, into a mixer. A third introduction step involves introducing the fourth gas discharged from the mixer into the adsorption device, The adsorption apparatus includes a purification step for obtaining hydrogen gas from the fourth gas, The first gas includes at least a portion of the off-gas discharged from the adsorption device. A method for operating a hydrogen gas production facility, comprising at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[15] A method for operating a gasification melting furnace system comprising a gas homogenizer described in any one of [1] to [9] above, a melting furnace, and a first adsorption device for purifying nitrogen gas used in the charging device of the melting furnace, A first introduction step involves introducing at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device as the first gas into the gas homogenization device, A second introduction step involves introducing the second gas and a first oxygen-containing gas containing oxygen as a third gas into a mixer. The process includes a third introduction step of introducing a second oxygen-containing gas, including a fourth gas discharged from the mixer, into the melting furnace. The first gas includes at least a portion of the off-gas discharged from the adsorption device. A method for operating a gasification melting furnace facility, comprising at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

[16] A method for producing hydrogen gas using a hydrogen gas production apparatus comprising: a plurality of tanks into which a first gas containing hydrogen gas and whose composition fluctuates over time is sequentially introduced; a flow path through which a second gas, which is discharged from at least one of the plurality of tanks and whose composition fluctuates over time less than that of the first gas, flows; a mixer that mixes the second gas with a third gas having a different composition from the first gas and the second gas to discharge a fourth gas; and an adsorption device having an adsorption tower, The system includes a separation step of introducing hydrogen gas and a fourth gas containing different components from the hydrogen gas into the adsorption device, separating the off-gas discharged from the adsorption device, and obtaining a plurality of off-gas with different average concentrations of hydrogen gas. The first gas includes at least a portion of the off-gas separated in the separation step, A method for producing hydrogen gas, comprising an adsorption apparatus including at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus.

[17] The method for producing hydrogen gas according to

[17] , wherein in the separation step, the off-gas discharged from the adsorption device is separated into a first off-gas and a second off-gas having a lower average concentration of hydrogen gas than the first off-gas.

[18] The method for producing hydrogen gas according to

[16] or

[17] , wherein the fourth gas comprises hydrogen gas obtained by decomposing ammonia.

[19] A method of ironmaking in which the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in any one of

[16] to

[18] above are used in the ironmaking process.

[20] A method of ironmaking in which the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in any one of

[16] to

[18] above are introduced into a blast furnace.

[21] A heat treatment method comprising introducing the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in any one of

[16] to

[18] above into a heating furnace.

[22] A method for producing iron ore, comprising introducing the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in any one of

[16] to

[18] above into a direct reduction furnace for iron ore.

[23] Multiple tanks into which a first gas whose composition changes over time is sequentially introduced, The system comprises a flow path through which a second gas, which is drawn from at least one of the aforementioned tanks and whose composition fluctuates less over time than that of the first gas, flows, The first gas includes at least a portion of the off-gas discharged from the adsorption device. The adsorption device includes at least one selected from the group consisting of a pressure swing adsorption device, a temperature swing adsorption device, and a pressure-temperature swing adsorption device, in a gas homogenization device. [Examples]

[0092] The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0093] (Example 1) As shown in Figure 8, the composition (volume ratio of oxygen gas and nitrogen gas) of the first gas (off-gas) obtained in the first adsorption device 10a fluctuates periodically. When this first gas is supplied to the gas homogenizer 120 of the gasification and melting furnace equipment 300 shown in Figure 7, the simulation results of the oxygen gas concentration and nitrogen gas concentration in the mixer 30 are shown in Figures 9(A) and 9(B), respectively. In this simulation, the mixer 30 has a cylindrical shape with an inner diameter of 1200 mm and a length of 4200 mm, and contains a total of 13 alternating disc-shaped (diameter: 1000 mm) and ring-shaped baffles (through-hole diameter: 350 mm) inside. As shown in Figure 8, the first gas with fluctuating composition was sequentially introduced into the first tank 21 and the second tank 22 to obtain a second gas with a reduced range of compositional fluctuation compared to the first gas. In mixer 30, a third gas mixture of oxygen gas:nitrogen gas = 90% by volume:10% by volume is added at 1000 Nm³. 3 The second gas, supplied at a flow rate of / h and homogenized in each tank, is then processed at 790 Nm³. 3 It was supplied at a flow rate of / h.

[0094] The horizontal axis in Figures 9(A) and 9(B) shows the 14 regions (stages) within the mixer 30, which is partitioned by 13 baffles, numbered sequentially from the upstream side. As shown in Figures 9(A) and 9(B), within the mixer 30, the influence of the compositional fluctuations of the first gas shown in Figure 8 was eliminated, and a homogeneous fourth gas could be obtained. From the third stage onward in the mixer 30, the composition of the fourth gas remained constant.

[0095] (Comparative Example 1) Without using multiple tanks 20, the oxygen and nitrogen gas concentrations at the outlet of the mixer 30 were simulated when the first gas, whose composition fluctuates as shown in Figure 8, was directly introduced into the mixer 30. The conditions were the same as in Example 1, except that multiple tanks 20 were not used. As a result, as shown in Figures 10(A) and 10(B), the composition of the fourth gas fluctuated periodically and was affected by the composition fluctuations of the first gas. Thus, it was confirmed that it is difficult to suppress composition fluctuations with the mixer 30 alone.

[0096] (Example 2) As shown in Figure 7, a simulation was conducted to determine how much the load on the second adsorption device 80 would be reduced when a gas homogenizer 120 was installed in the gasification and melting furnace equipment 300. As shown in Figure 11, the first gas (off-gas with an average oxygen gas concentration of 33 volume%) was released from the first adsorption device 10a at a rate of 790 Nm³. 3 The gas was assumed to be generated at a rate of / h. Air was supplied to the second adsorption device 80 to obtain a third gas with an oxygen gas concentration of 90 vol%. The fourth gas discharged from the mixer 30 was pressurized by a blower and then mixed with air to become oxygen-enriched air with an oxygen gas concentration of 38 vol%, which was then supplied to the melting furnace 70 from the lower tuyere at a rate of 4000 Nm³. 3 The air was supplied at a flow rate of / h. In this case, the amount of air introduced into the second adsorption device 80 was 865 Nm³. 3 It was / h.

[0097] (Comparative Example 2) We simulated how much air would be introduced into the second adsorption device 80 if the off-gas from the first adsorption device 10a was released without recovery, without using multiple tanks 20 and mixer 30. In order to make the flow rate and oxygen gas concentration of the oxygen-enriched air introduced into the melting furnace 70 from the lower tuyere the same as in Example 2, as shown in Figure 12, 1000 Nm of air was introduced into the second adsorption device 80. 3 It was necessary to introduce the system at a flow rate of / h.

[0098] From the results of Example 2 and Comparative Example 2, it was confirmed that the load on the second adsorption device 80 could be sufficiently reduced by recovering off-gas with an average oxygen gas concentration of 33 volume percent generated from the first adsorption device 10a. Note that the "%" shown in Figures 11 and 12 are volume-based values. [Explanation of symbols]

[0099] 10...Adsorption device, 10a...First adsorption device, 10A...First adsorption tower, 10B...Second adsorption tower, 10C...Third adsorption tower, 10D...Fourth adsorption tower, 12,13,14,44,51,52,53,54...Flow channels, 20,20A...Multiple tanks, 21...First tank, 22...Second tank, 23...Third tank, 24...Fourth tank, 25...Fifth tank, 26...Sixth tank, 27...Seventh tank, 30...Mixer, 30A...Pre-mixer, 31,32,3 3, 35, 36, 37... Baffle plates, 38, 39... Container body, 40... Compressor, 60... Charging device, 62... Exhaust gas pipe, 70... Melting furnace, 71... Carbon material packed bed, 72... Shaft section, 73... Pyrolysis residue, 74... Morning glory section, 75... Upper tuyere, 76... Furnace bottom, 77... Lower tuyere, 78... Waste, 79... Slag outlet, 80... Second adsorption device, 100, 110, 120... Gas homogenization device, 200, 210... Hydrogen gas production equipment, 300... Gasification melting furnace equipment.

Claims

1. Multiple tanks into which the first gas, whose composition changes over time, is sequentially introduced, The system comprises a flow path through which a second gas, which is drawn from at least one of the aforementioned tanks and whose composition fluctuates less over time than that of the first gas, flows, The first gas includes at least a portion of the off-gas discharged from the adsorption device. The adsorption device includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device, and is a gas homogenization device.

2. The gas homogenization apparatus according to claim 1, wherein the composition of the first gas fluctuates periodically.

3. The gas homogenization apparatus according to claim 1 or 2, further comprising a mixer for mixing the second gas with a third gas having a different composition from the first gas and the second gas to produce a fourth gas.

4. The flow path of the off-gas discharged from the adsorption tower of the adsorption device is divided into multiple branches. The gas homogenization apparatus according to claim 2, wherein the off-gas is separated into a plurality of off-gas having different average concentrations of hydrogen, and the separated off-gas are sequentially introduced into the plurality of tanks as the first gas.

5. The system includes a switching unit that switches which tank the first gas is introduced into so that the first gas is introduced into each of the plurality of tanks sequentially. The gas homogenization apparatus according to claim 1 or 2, wherein the switching unit switches the tank according to the period of compositional fluctuation of the first gas.

6. The system includes a switching unit that switches which tank the first gas is introduced into so that the first gas is introduced into each of the plurality of tanks sequentially. The gas homogenization apparatus according to claim 1 or 2, wherein the switching unit switches the tank at a period shorter than the period of compositional fluctuation of the first gas.

7. The gas homogenization apparatus according to claim 1 or 2, wherein the total number of the plurality of tanks is greater than the number of tanks into which the first gas is introduced per cycle of the composition variation of the first gas.

8. A hydrogen gas production apparatus comprising a gas homogenization apparatus according to claim 1 or 2, and the adsorption apparatus for purifying hydrogen gas, At least a portion of the off-gas containing hydrogen gas discharged from the adsorption device is introduced into the gas homogenization device as the first gas. The second gas and a third gas containing hydrogen gas and nitrogen gas, and having a different composition from the first gas and the second gas, are introduced into the mixer. The gas containing the fourth gas discharged from the mixer is introduced into the adsorption device. The adsorption apparatus includes at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus, and is a hydrogen gas production facility.

9. The hydrogen gas production apparatus according to claim 8, wherein the average concentration of hydrogen gas in the off-gas introduced into the gas homogenizer as the first gas is 40% by volume or more.

10. A gasification and melting furnace apparatus comprising: a gas homogenization apparatus according to claim 1 or 2; a melting furnace; a charging apparatus provided above the melting furnace; and a first adsorption apparatus for purifying nitrogen gas used in the charging apparatus, At least a portion of the off-gas containing oxygen gas discharged from the first adsorption device is introduced into the gas homogenization device as the first gas. The second gas and a first oxygen-containing gas containing oxygen as a third gas are introduced into the mixer. The second oxygen-containing gas, including the fourth gas discharged from the mixer, is introduced into the melting furnace. The first adsorption device is a gasification melting furnace facility that includes at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

11. The gasification melting furnace apparatus according to claim 10, further comprising a second adsorption device for obtaining the first oxygen-containing gas having a higher oxygen gas concentration than the air as the third gas from air.

12. An introduction process in which a first gas whose composition changes over time is sequentially introduced into multiple tanks, A discharge step of dischargeing a second gas from at least one of the plurality of tanks, the second gas having a reduced range of temporal compositional fluctuations than the first gas, The process includes a mixing step of mixing the second gas and a third gas having a different composition from the first and second gases in a mixer to obtain a fourth gas, The first gas includes at least a portion of the off-gas discharged from the adsorption device. A gas homogenization method comprising an adsorption apparatus including at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus.

13. The flow path leading out from the adsorption tower of the adsorption apparatus is divided into multiple branches, and the off-gas led out from the adsorption tower is divided into multiple parts, The gas homogenization method according to claim 12, wherein a portion of the separated off-gas is sequentially introduced into the plurality of tanks as the first gas.

14. A method for operating a hydrogen gas production facility comprising a gas homogenization device according to claim 1 or 2 and an adsorption device for purifying hydrogen gas, A first introduction step involves introducing at least a portion of the off-gas containing hydrogen gas discharged from the adsorption device as the first gas into the gas homogenization device, A second introduction step involves introducing the second gas and a third gas, which includes hydrogen gas and nitrogen gas and has a different composition from the first gas and the second gas, into a mixer. A third introduction step involves introducing the fourth gas discharged from the mixer into the adsorption device, The adsorption apparatus includes a purification step for obtaining hydrogen gas from the fourth gas, The first gas includes at least a portion of the off-gas discharged from the adsorption device. A method for operating a hydrogen gas production facility, comprising at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

15. A method for operating a gasification melting furnace system comprising a gas homogenization device according to claim 1 or 2, a melting furnace, and a first adsorption device for purifying nitrogen gas used in the charging device of the melting furnace, A first introduction step involves introducing at least a portion of the off-gas containing oxygen gas discharged from the first adsorption device as the first gas into the gas homogenization device, A second introduction step involves introducing the second gas and a first oxygen-containing gas containing oxygen as a third gas into a mixer. The process includes a third introduction step of introducing a second oxygen-containing gas, including a fourth gas discharged from the mixer, into the melting furnace. The first gas includes at least a portion of the off-gas discharged from the adsorption device. A method for operating a gasification melting furnace facility, comprising at least one of a temperature swing adsorption device and a pressure-temperature swing adsorption device.

16. A method for producing hydrogen gas using a hydrogen gas production apparatus comprising: a plurality of tanks into which a first gas containing hydrogen gas and whose composition fluctuates over time is sequentially introduced; a flow path through which a second gas, which is discharged from at least one of the plurality of tanks and whose composition fluctuates over time less than that of the first gas, flows; a mixer that mixes the second gas with a third gas having a different composition from the first gas and the second gas to discharge a fourth gas; and an adsorption device having an adsorption tower, wherein The system includes a separation step of introducing hydrogen gas and a fourth gas containing different components from the hydrogen gas into the adsorption device, separating the off-gas discharged from the adsorption device to obtain a plurality of off-gas with different average concentrations of hydrogen gas, The first gas includes at least a portion of the off-gas separated in the separation step, A method for producing hydrogen gas, comprising an adsorption apparatus including at least one of a temperature swing adsorption apparatus and a pressure-temperature swing adsorption apparatus.

17. The method for producing hydrogen gas according to claim 16, wherein the separation step separates the off-gas discharged from the adsorption device into a first off-gas and a second off-gas having a lower average concentration of hydrogen gas than the first off-gas.

18. The method for producing hydrogen gas according to claim 16 or 17, wherein the fourth gas includes hydrogen gas obtained by decomposing ammonia.

19. A method for making iron, comprising using the hydrogen gas and / or the plurality of off-gases obtained by the method for producing hydrogen gas according to claim 16 or 17 in an ironmaking process.

20. A method for ironmaking, comprising introducing the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in claim 16 or 17 into a blast furnace.

21. A heat treatment method comprising introducing the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in claim 16 or 17 into a heating furnace.

22. A method for producing iron ore, comprising introducing the hydrogen gas and / or the plurality of off-gases obtained by the hydrogen gas production method described in claim 16 or 17 into a direct reduction furnace for iron ore.

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