Method for separating and recovering carbon dioxide and method for producing methanol
A method for separating and recovering CO2 from blast furnace gas by dehumidification, carbonyl sulfide hydrolysis, and desulfurization addresses the issue of sulfur compound interference, ensuring effective CO2 recovery and catalyst protection for methanol synthesis.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2024-10-21
- Publication Date
- 2026-05-15
AI Technical Summary
Blast furnace gas contains sulfur compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS) that are adsorbed with CO2, leading to catalyst degradation in methanol synthesis when introduced into the methanol synthesis facility.
A method involving dehumidification, carbonyl sulfide hydrolysis, desulfurization, and pressure swing adsorption to separate and recover CO2 from a raw material gas containing CO2, H2S, and COS, including steps like moisture removal, COS conversion to H2S and CO2, and use of specific catalysts and desulfurization agents.
The method effectively removes H2S and COS, preventing catalyst degradation and enabling efficient CO2 recovery for methanol synthesis.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for separating and recovering carbon dioxide and a method for producing methanol.
Background Art
[0002] In recent years, reduction of carbon dioxide (CO2) emissions has been demanded to prevent global warming. In steelworks, a large amount of by-product gases such as blast furnace gas by-produced in blast furnaces, coke oven gas generated from coke ovens, and converter gas generated from converters are discharged. Among them, especially blast furnace gas with a large discharge amount is utilized as an energy source in the steelworks, but a large amount of CO2 is contained in blast furnace gas and it is discharged as it is. Therefore, separating CO2 from blast furnace gas and effectively using it is an important issue.
[0003] As a method for effectively using CO2, a method of converting CO2 into valuable substances such as methanol or methane using a catalyst can be mentioned. For example, Patent Document 1 proposes a method for synthesizing methanol from a raw material gas containing CO2 and hydrogen (H2) using a catalyst.
[0004] The catalysts used for the synthesis of the above methanol and methane are deteriorated by sulfur compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS) in blast furnace gas. Therefore, for effective utilization of CO2 contained in blast furnace gas, separation and desulfurization of CO2 from blast furnace gas are necessary.
[0005] As a method for separating CO2, a pressure swing adsorption (PSA) method that utilizes the pressure dependence of the adsorption amount in an adsorbent such as zeolite can be mentioned. For example, Patent Document 2 proposes a method for separating and recovering CO2 from a raw material gas containing CO2 using the PSA method.
[0006] A possible process for separating CO2 from reducing furnace gases such as blast furnace gas (gases containing CO2, carbon monoxide (CO), H2, nitrogen (N2), water (H2O), H2S, and COS) using the PSA method described in Patent Document 2, and then synthesizing methanol with a catalyst, is shown in Figure 1.
[0007] First, the raw material gas G01, such as the reduction furnace gas, is introduced into a dehumidification device 1 installed before the CO2 separation by the PSA device 2 to dehumidify the raw material gas G01 and reduce its H2O concentration. This is because, in the PSA method, if the H2O concentration in the raw material gas is high, the CO2 separation capacity decreases significantly.
[0008] Next, the dehumidified raw material gas G01, with reduced H2O concentration, is introduced into the PSA unit 2. In the PSA unit 2, first, in the adsorption process, the dehumidified raw material gas G01 is introduced into the adsorption tower of the PSA unit 2, and CO2 is adsorbed onto the adsorbent packed in the adsorption tower, while the non-adsorbed gas G02, which contains non-adsorbed gas components that were not adsorbed onto the adsorbent, is discharged.
[0009] Next, in the desorption process, pump 3A reduces the pressure inside the adsorption tower to desorb the CO2 adsorbed on the adsorbent, and the gas containing CO2 is discharged from the adsorption tower as desorption gas G03.
[0010] The discharged desorption gas G03 is compressed by compressor 3B, then mixed with H2 gas G04 and sent to methanol synthesis equipment 4, where methanol G05 is synthesized by the reaction shown in equation (1) below. CO2 + 3H2 → CH3OH + H2O (1) [Prior art documents] [Patent Documents]
[0011] [Patent Document 1] Patent No. 7049075 [Patent Document 2] Patent No. 6677181 [Overview of the Initiative] [Problems that the invention aims to solve]
[0012] As mentioned above, blast furnace gas contains not only the main gaseous components such as CO2, CO, and H2, but also gaseous components containing sulfur (S) derived from iron ore and coke, such as H2S and COS. These H2S and COS are adsorbed together with CO2 onto the adsorbent in the adsorption tower. Therefore, when blast furnace gas is used as the raw material gas G01, H2S and COS are separated and recovered from the raw material gas G01 along with CO2, resulting in the problem of them becoming impurities in the CO2 gas. When this desorption gas G03 containing H2S and COS is introduced into the methanol synthesis facility 4 to carry out the methanol synthesis reaction, it degrades the catalyst used in the methanol synthesis reaction.
[0013] The present invention has been made in view of the above problems, and its objective is to propose a carbon dioxide separation and recovery method that can separate and recover carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by removing hydrogen sulfide and carbonyl sulfide. [Means for solving the problem]
[0014] [1] A method for separating and recovering carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by pressure swing adsorption, A dehumidification step is performed to remove moisture from the aforementioned raw material gas to obtain a dehumidified raw material gas. A carbon dioxide separation and recovery method comprising a carbon dioxide recovery step of separating and recovering carbon dioxide gas from the dehumidified raw material gas by a pressure swing adsorption method, A carbonyl sulfide hydrolysis step is performed by reacting the carbonyl sulfide with water to hydrolyze it into hydrogen sulfide and carbon dioxide. The desulfurization process separates hydrogen sulfide, A method for separating and recovering carbon dioxide, including carbon dioxide.
[0015] [2] The carbon dioxide separation and recovery method according to [1], wherein the carbonyl sulfide hydrolysis step is preceding the dehumidification step.
[0016] [3] The carbon dioxide separation and recovery method according to [2], wherein the desulfurization step is located after the carbon dioxide recovery step.
[0017] [4] The carbon dioxide separation and recovery method according to [2], wherein the desulfurization step is located after the carbonyl sulfide hydrolysis step and before the carbon dioxide recovery step.
[0018] [5] The carbon dioxide separation and recovery method according to [1], wherein the carbonyl sulfide hydrolysis step is located after the carbon dioxide recovery step.
[0019] [6] The carbon dioxide separation and recovery method according to [5], further comprising a humidification step for adjusting the moisture content of the carbon dioxide gas, which is located after the carbon dioxide recovery step and before the carbonyl sulfide hydrolysis step.
[0020] [7] The carbon dioxide separation and recovery method according to [6], wherein the humidification step is a water washing step for washing the carbon dioxide gas with water.
[0021] [8] The carbon dioxide separation and recovery method according to [6], wherein the humidification step is a water vapor addition step for adding water vapor to the carbon dioxide gas.
[0022] [9] The carbon dioxide separation and recovery method according to any one of [1] to [8], wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing an aluminum oxide.
[0023]
[10] The carbon dioxide separation and recovery method according to any one of [1] to [8], wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing either or both of a cobalt oxide or sulfide and a molybdenum oxide or sulfide.
[0024]
[11] The carbon dioxide separation and recovery method according to any one of [1] to
[10] , wherein the desulfurization agent used in the desulfurization step is a dry desulfurization agent, and the dry desulfurization agent contains at least one selected from the group consisting of iron oxide, copper oxide, and zinc oxide.
[0025]
[12] The carbon dioxide separation and recovery method according to
[11] , wherein at least two types of the dry desulfurization agents are used in the desulfurization step, at least one type of the dry desulfurization agent contains iron oxide, and at least one type of the dry desulfurization agent contains copper oxide.
[0026]
[13] The carbon dioxide separation and recovery method according to any one of [1] to
[12] , further comprising a compression step of pressurizing the carbon dioxide gas into a compressed gas, and supplying the compressed gas to the desulfurization step.
[0027]
[14] The carbon dioxide separation and recovery method according to any one of [1] to
[13] , wherein the raw material gas is a reduction furnace gas.
[0028]
[15] The carbon dioxide separation and recovery method according to
[14] , wherein the reduction furnace gas is a blast furnace gas.
[0029]
[16] A method for producing methanol, wherein hydrocarbons or methanol are synthesized from carbon dioxide obtained by using the carbon dioxide separation and recovery method according to any one of [1] to
[15] . [Effect of the Invention]
[0030] According to the present invention, carbon dioxide from which hydrogen sulfide and carbonyl sulfide have been removed can be separated and recovered from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide. [Brief Description of the Drawings]
[0031] [Figure 1] It is a diagram showing a flow of an example of a conventional carbon dioxide separation and recovery method. [Figure 2] It is a diagram showing a flow of a preferred example of the carbon dioxide separation and recovery method according to the present invention. [Figure 3] This figure shows a flow chart of a preferred example of a methanol production method according to the present invention. [Modes for carrying out the invention]
[0032] Embodiments of the present invention will be described below with reference to the drawings. The carbon dioxide separation and recovery method according to the present invention is a method for separating and recovering carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by a pressure swing adsorption method, comprising a dehumidification step of removing moisture from the raw material gas to obtain a dehumidified raw material gas, and a carbon dioxide recovery step of separating and recovering carbon dioxide gas from the dehumidified raw material gas by a pressure swing adsorption method. Herein, the above method is characterized by including a carbonyl sulfide hydrolysis step of reacting carbonyl sulfide with moisture to hydrolyze it into hydrogen sulfide and carbon dioxide, and a desulfurization step of separating hydrogen sulfide.
[0033] The inventors diligently investigated methods for separating and recovering CO2 from a raw material gas containing CO2, H2S, and COS, after removing H2S and COS. As a result, they conceived of pre-hydrolyzing COS, which is relatively difficult to remove, to convert it to H2S as shown in formula (2) below, and then desulfurizing the obtained H2S together with the H2S originally contained in the raw material gas. This allows for obtaining CO2 from which H2S and COS have been removed from the raw material gas, and when the obtained CO2 gas is introduced into the methanol synthesis equipment 4 to synthesize methanol, the degradation of the catalyst used in the methanol synthesis reaction can be suppressed. COS + H2O → CO2 + H2S (2)
[0034] Figure 2 shows a flow chart of a preferred example of the carbon dioxide separation and recovery method according to the present invention. In Figure 2, the same components as those shown in Figure 1 are denoted by the same reference numerals. The carbon dioxide separation and recovery method according to the present invention will be specifically described below using the flow chart shown in Figure 2, but the present invention is not limited thereto.
[0035] First, the raw material gas G01 is introduced into the humidity control equipment 5 to adjust the H2O concentration of the raw material gas G01 (humidity control process). The raw material gas G01 is a gas containing CO2, H2S, and COS. Examples of such gases include by-product gases discharged from steel mills. Examples of by-product gases include reduction furnace gases containing CO2, CO, N2, H2, H2S, and COS, such as blast furnace gas, coke oven gas, and converter gas. The present invention can effectively remove COS and H2S from blast furnace gas among the above gases, separate and recover CO2 gas, and reduce CO2 emissions.
[0036] The humidity control equipment 5 is equipment that adjusts the H2O concentration of the raw material gas G01. Such humidity control equipment 5 can consist of a water washing equipment that washes the raw material gas G01 with water. In this case, the humidity control process is configured as a water washing process. In the water washing process, the H2O concentration of the raw material gas G01 can be adjusted by adjusting the water temperature. In addition, the water washing process can remove water-soluble gas components such as HCl and NH3 if the raw material gas G01 contains these water-soluble gas components.
[0037] Furthermore, the humidity control equipment 5 can be composed of a water vapor addition equipment that adds water vapor to the raw material gas G01. In this case, the humidity control process is composed of a water vapor addition process. In the water vapor addition equipment, the H2O concentration of the raw material gas G01 can be controlled by the flow rate of water vapor.
[0038] Next, the raw material gas G01, whose H2O concentration has been adjusted in the humidity control process, is introduced into the COS hydrolysis equipment 6, and the COS contained in the raw material gas G01 is reacted with H2O according to formula (2) above to hydrolyze it into H2S and CO2 (carbonyl sulfide hydrolysis process).
[0039] The COS hydrolysis apparatus 6 can consist of a catalyst-packed column filled with a catalyst that promotes the reaction of formula (2) above. The catalyst to be packed may be a catalyst containing aluminum (Al) oxide. In addition, the catalyst may include cobalt (Co) oxide or sulfide, molybdenum (Mo) oxide or sulfide, or both.
[0040] In this carbonyl sulfide hydrolysis process, COS contained in the raw material gas G01 can be hydrolyzed by passing the raw material gas G01 containing COS and H2O through the COS hydrolysis equipment 6. The temperature of the COS hydrolysis equipment 6, such as a catalyst-packed tower (i.e., the temperature of the catalyst in the packed tower), is preferably set to 100°C or higher from the viewpoint of preventing H2O condensation. H2S is often more reactive with dry desulfurizing agents than COS, and converting it to H2S improves the efficiency of the dry desulfurizing agent.
[0041] Next, the raw material gas G01, in which COS has been converted to H2S, is introduced into dehumidification equipment 1, where moisture is removed from the raw material gas G01 to obtain the dehumidified raw material gas (dehumidification process).
[0042] Dehumidification equipment 1 can be configured as a dehumidifying device that cools the raw material gas G01 to condense and remove H2O. Alternatively, dehumidification equipment 1 can be configured as a desiccant type facility such as a packed adsorption tower filled with an adsorbent that adsorbs H2O, such as Al oxide, silicon (Si) oxide, or zeolite.
[0043] The dehumidification process is preferably carried out until the dew point of the raw material gas G01 is 0°C or below, and more preferably until it is -20°C or below. This helps to suppress a decrease in the amount of CO2 adsorbed by the adsorbent in the subsequent carbon dioxide recovery process.
[0044] Subsequently, the dehumidified raw material gas G01 obtained in the dehumidification process is introduced into the PSA device 2, and CO2 gas is separated and recovered from the dehumidified raw material gas G01 by the PSA method (carbon dioxide recovery process).
[0045] The PSA device 2 can be configured as an adsorption tower filled with an adsorbent that adsorbs CO2, such as zeolite. In the adsorption process, the dehumidified raw material gas G01 is circulated through the adsorption tower to adsorb CO2 onto the adsorbent, and the non-adsorbed gas components that were not adsorbed onto the adsorbent are discharged from the adsorption tower as non-adsorbed gas G02. Then, in the desorption process, the inside of the adsorption tower is depressurized using pump 3 to desorb CO2 from the adsorbent, and the desorbed gas G03 containing the desorbed CO2 is separated and recovered. At this time, the gas pressure on the inlet side of pump 3 is, for example, 1 kPa or more and 20 kPa or less, and the gas pressure on the outlet side of pump 3 is, for example, 100 kPa or more. In this carbon dioxide recovery process, if the raw material gas G01 is blast furnace gas, CO, N2, and H2 in the raw material gas G01 are mainly separated into non-adsorbed gas G02, and CO2, H2S, COS, and H2O are mainly separated into desorbed gas G03.
[0046] The pressure inside the adsorption tower during the desorption process described above is preferably 1 kPa or more and 20 kPa or less, and more preferably 5 kPa or more and 10 kPa or less.
[0047] Next, the desorbed gas G03 is introduced into the desulfurization equipment 7 to separate the H2S contained in the desorbed gas G03 (desulfurization process).
[0048] The desulfurization equipment 7 can be configured as a desulfurizing agent packed tower filled with a dry desulfurizing agent that adsorbs H2S. By circulating the desorption gas 03 through the desulfurizing agent packed tower, H2S can be adsorbed onto the desulfurizing agent and desulfurized.
[0049] Examples of dry desulfurizing agents include iron (Fe) oxides, copper (Cu) oxides, and zinc (Zn) oxides, and a desulfurizing agent containing one or more selected from the group consisting of these oxides can be used.
[0050] Furthermore, it is preferable to use at least two types of dry desulfurizing agents, with at least one dry desulfurizing agent containing an iron oxide and at least one dry desulfurizing agent containing a copper oxide. Various combinations of desulfurizing agents and the order in which they are used can be considered, but it is preferable to first remove H2S contained in the desorption gas G03 with an inexpensive iron oxide-containing dry desulfurizing agent, and then remove the remaining H2S and COS with a copper oxide-containing dry desulfurizing agent.
[0051] The desulfurization process using at least two types of desulfurizing agents described above can be carried out by installing more desulfurizing agent packed towers than the number of types of desulfurizing agents, filling each desulfurizing agent packed tower with a desulfurizing agent, and sequentially circulating the desorbed gas G03 through each desulfurizing agent packed tower, thereby desulfurizing the desorbed gas G03. For example, when using two types of dry desulfurizing agents, two desulfurizing agent packed towers 7A and 7B are installed as shown in Figure 2, a dry desulfurizing agent containing Fe oxide is packed into desulfurizing agent packed tower 7A, and a dry desulfurizing agent containing Cu oxide is packed into desulfurizing agent packed tower 7B. Then, by sequentially circulating the desorbed gas G03 through desulfurizing agent packed towers 7A and 7B, the desulfurizing gas G03 can be desulfurized to obtain CO2 gas G06, which is desorbed gas G03 with reduced H2S and COS concentrations.
[0052] In the above description, the COS hydrolysis equipment 6 is located before the dehumidification equipment 1, and the carbonyl sulfide hydrolysis process is performed before the dehumidification process. However, the description is not limited to this configuration, and the COS hydrolysis equipment 6 can also be located after the PSA equipment 2, so that the carbonyl hydrolysis process is performed after the carbon dioxide recovery process.
[0053] However, in the COS hydrolysis process, it is preferable to use raw material gas G01 with an H2O concentration of 1% or more. However, dehumidification equipment 1 is installed to maintain the performance of the PSA unit 2, and there is no equipment to increase the H2O concentration downstream of dehumidification equipment 1. Therefore, if the H2O concentration is low and COS cannot be sufficiently hydrolyzed in the COS hydrolysis process, COS that is difficult to react with the desulfurizing agent will remain in the gas, potentially flowing into the catalyst of the desulfurization equipment 7 downstream and degrading the catalyst. On the other hand, the raw material gas G01 after the water washing process has an H2O concentration close to the vapor pressure at that temperature. For example, if the water washing process is performed at 25°C, the H2O concentration of the raw material gas G01 can be easily made 1% or more. Therefore, the raw material gas G01 after the water washing process is suitable for COS hydrolysis. Thus, as shown in Figure 2, it is preferable to install the COS hydrolysis equipment 6 before the dehumidification equipment 1 and perform the carbonyl sulfide hydrolysis process before the dehumidification process.
[0054] When the COS hydrolysis equipment 6 is installed downstream of the PSA apparatus 2 and the carbonyl hydrolysis process is performed downstream of the carbon dioxide recovery process, it is preferable to further install a humidity control equipment 5 downstream of the PSA apparatus 2 and upstream of the COS hydrolysis equipment 6, and to further perform a humidity control process to adjust the moisture content of the carbon dioxide gas downstream of the carbon dioxide recovery process and upstream of the carbonyl sulfide hydrolysis process. This allows for sufficient hydrolysis of the COS contained in the desorption gas G03.
[0055] Furthermore, in Figure 2, the desulfurization equipment 7 is located downstream of the PSA device 2, and the desulfurization process is performed downstream of the carbon dioxide recovery process. This is because the performance of adsorbents such as zeolite used in the carbon dioxide recovery process is not degraded by H2S and COS, so there is no need to install the desulfurization equipment 7 upstream of the PSA device 2. However, it is also possible to install the desulfurization equipment 7 upstream of the PSA device 2 and configure the desulfurization process to be performed upstream of the carbon dioxide recovery process. Moreover, it is also possible to install the desulfurization equipment 7 upstream of the PSA device 2 and downstream of the COS hydrolysis equipment 6, and configure the desulfurization process to be performed downstream of the carbonyl sulfide hydrolysis process and upstream of the carbon dioxide recovery process.
[0056] However, from the viewpoint of suppressing carbon deposition (coking) originating from CO in the gas, a gas with a low CO concentration is preferable. Therefore, it is preferable to install the desulfurization equipment 7 downstream of the PSA device 2 and perform the desulfurization process downstream of the carbon dioxide recovery process. In addition, adsorbents such as zeolite used in the PSA method also adsorb H2S and COS. For this reason, by installing the desulfurization equipment 7 downstream of the PSA device 2, H2S and COS are concentrated in the desorbed gas G03, which contains CO2 discharged from the PSA device 2. Since the desorbed gas G03 has a higher concentration of H2S and COS than the raw material gas G01 and its flow rate is reduced, there is also the effect of increasing the desulfurization capacity and reducing the amount of H2S and COS that slips out of the outlet of the desulfurization equipment 7.
[0057] Figure 3 shows a flow chart of a preferred example of the methanol production method according to the present invention. In Figure 3, components identical to those shown in Figure 2 are denoted by the same reference numerals. The difference between the flow chart in Figure 3 and the flow chart in Figure 2 is that in the flow chart in Figure 3, the COS hydrolysis equipment 16 is configured to perform a water-gas shift reaction step in addition to the COS hydrolysis step. Furthermore, in the flow chart in Figure 3, the desorbed gas G03 is introduced into the compressor 3B, and a compression step is performed in which the desorbed gas G03 is pressurized to a pressure of 1000 kPa or more to produce compressed gas. In addition, in the flow chart in Figure 3, the CO2 gas G06 from which H2S and COS have been removed by the desulfurization step is introduced into the methanol synthesis equipment 4 to produce methanol G05. The differences will be explained below.
[0058] First, in order to carry out the water-gas shift reaction process in the COS hydrolysis plant 16, the humidity control plant 5 consists of a humidity control plant 5A that performs a water washing process and a humidity control plant 5B that performs a water vapor addition process in which water vapor G07 is added to the raw material gas G01. First, the raw material gas G01 is introduced into the humidity control plant 5A and the water washing process is performed to adjust the H2O concentration of the raw material gas G01. Next, the raw material gas G01 with the adjusted H2O concentration is introduced into the humidity control plant 5B, and water vapor is added to the raw material gas G01 to increase the H2O concentration. Then, the raw material gas G01 with the increased H2O concentration is introduced into the COS hydrolysis plant 16, and the carbonyl sulfide hydrolysis process and the water-gas shift reaction process are carried out. This makes it possible to improve the CO2 treatment efficiency.
[0059] In the humidity control equipment 5B, water vapor G07 is added to the raw material gas G01. From the viewpoint of preventing carbon deposition on the catalyst in the COS hydrolysis equipment 16, it is preferable to set the molar ratio of H2O / CO in the raw material gas G01 after the addition of water vapor G07 to 1.0 or higher, and more preferably to 2.0 or higher. Furthermore, since the water-gas shift reaction is an exothermic reaction and lower temperatures are more favorable in terms of chemical equilibrium, it is preferable to set the temperature of the catalyst in the COS hydrolysis equipment 16 to 200°C or higher and 500°C or lower, and more preferably to 200°C or higher and 400°C or lower. Similarly, it is preferable to set the temperature of the raw material gas G01 after the addition of water vapor G07 to 200°C or higher and more preferably to 500°C or lower, and more preferably to 200°C or higher and 400°C or lower.
[0060] Following the above COS hydrolysis step and water-gas shift reaction step, a dehumidification step is performed in the dehumidification equipment 1 to remove H2O from the raw material gas G01 to obtain dehumidified raw material gas G01. The dehumidification step is preferably performed so that the dew point of the raw material gas G01 is 0°C or lower, and more preferably so that it is -20°C or lower. Subsequently, in the adsorption step, the dehumidified raw material gas G01 is circulated through the PSA apparatus 2 equipped with an adsorbent-packed tower filled with zeolite as an adsorbent to adsorb CO2 onto the adsorbent, and the non-adsorbed gas G02 containing non-adsorbed gas components that were not adsorbed onto the adsorbent is discharged. Then, in the desorption step, the inside of the adsorption tower is depressurized by pump 3A to desorb CO2 from the adsorbent, and the gas containing CO2 is discharged from the adsorption tower as desorbed gas G03.
[0061] Next, the desorbed gas G03 discharged from the adsorption tower is introduced into the compressor 3B and pressurized. The pressure of the desorbed gas G03 can be set to an appropriate value based on the subsequent reaction. In the preceding PSA apparatus 2, when methanol is synthesized, it is preferable to set the pressure of the desorbed gas G03 via the compressor 3B to between 1 MPa and 10 MPa.
[0062] The desorbed gas G03 is then passed through a desulfurizing agent packed tower 7A, which is filled with a dry desulfurizing agent containing Fe oxide, and then through a desulfurizing agent packed tower 7B, which is filled with a dry desulfurizing agent containing Cu oxide, to reduce the H2S and COS concentrations of the desorbed gas G03. The desorbed gas G03 with reduced H2S and COS concentrations is recovered as CO2 gas G06. Using pressurized desorbed gas G03 is preferable because it is expected to increase the desulfurization capacity and accelerate the desulfurization reaction. To improve the desulfurization performance of the desulfurizing agent packed tower 7B, a dehumidification process may be performed by installing a dehumidification device 1 in the preceding stage.
[0063] Then, CO2 gas G06 is mixed with H2 gas G04 and introduced into methanol synthesis equipment 4, where methanol G05 is synthesized by the reaction of formula (1) above. Since H2S and COS have been removed from CO2 gas G06, which is the raw material for methanol G05, the degradation of the catalyst used in the methanol G05 synthesis reaction can be suppressed.
[0064] In the above description, methanol G05 is produced in methanol synthesis equipment 4, but it may also be configured to produce hydrocarbons. In that case, a hydrocarbon synthesis facility filled with a hydrocarbon synthesis catalyst may be used instead of methanol synthesis equipment 4. For example, if the hydrocarbon to be synthesized is methane, the hydrocarbon synthesis facility may be configured to maintain a reaction vessel filled with a Ni-containing catalyst at a temperature between 200°C and 400°C, and to circulate CO2 gas G06 and H2 gas G04. [Industrial applicability]
[0065] According to the present invention, carbon dioxide can be separated and recovered from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide, after removing hydrogen sulfide and carbonyl sulfide. [Explanation of Symbols]
[0066] 1 Dehumidification equipment 2. Pressure Swing Device 3.3A pump 3B Compressor 4. Methanol synthesis equipment 5,5A,5B Humidity control equipment 6,16 Carbonyl sulfide hydrolysis equipment 7 Desulfurization equipment G01 Raw material gas G02 Non-adsorbent gas G03 Detachable Gas G04 Hydrogen gas G05 Methanol G06 Carbon Dioxide Gas G07 Water vapor
Claims
1. A method for separating and recovering carbon dioxide from a raw material gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by pressure swing adsorption, A dehumidification step is performed to remove moisture from the aforementioned raw material gas to obtain a dehumidified raw material gas. A carbon dioxide separation and recovery method comprising a carbon dioxide recovery step of separating and recovering carbon dioxide gas from the dehumidified raw material gas by a pressure swing adsorption method, A carbonyl sulfide hydrolysis step is performed by reacting the carbonyl sulfide with water to hydrolyze it into hydrogen sulfide and carbon dioxide. The desulfurization process separates hydrogen sulfide, Includes, The carbonyl sulfide hydrolysis step is located after the carbon dioxide recovery step. Methods for separating and capturing carbon dioxide.
2. The carbon dioxide separation and recovery method according to claim 1, further comprising a humidity control step for adjusting the moisture content of the carbon dioxide gas, which is located after the carbon dioxide recovery step and before the carbonyl sulfide hydrolysis step.
3. The carbon dioxide separation and recovery method according to claim 2, wherein the humidity control step is a washing step of washing the carbon dioxide gas with water.
4. The carbon dioxide separation and recovery method according to claim 2, wherein the humidity control step is a water vapor addition step of adding water vapor to the carbon dioxide gas.
5. The carbon dioxide separation and recovery method according to any one of claims 1 to 4, wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing an aluminum oxide.
6. The carbon dioxide separation and recovery method according to any one of claims 1 to 4, wherein the catalyst used in the carbonyl sulfide hydrolysis step is a catalyst containing either or both of cobalt oxide or sulfide, molybdenum oxide or sulfide.
7. The carbon dioxide separation and recovery method according to any one of claims 1 to 4, wherein the desulfurizing agent used in the desulfurization step is a dry desulfurizing agent, and the dry desulfurizing agent comprises at least one selected from the group consisting of iron oxide, copper oxide, and zinc oxide.
8. The carbon dioxide separation and recovery method according to claim 7, wherein at least two types of dry desulfurizing agents are used in the desulfurization step, at least one of the dry desulfurizing agents contains an iron oxide, and at least one of the dry desulfurizing agents contains a copper oxide.
9. A method for separating and recovering carbon dioxide according to any one of claims 1 to 4, further comprising a compression step of pressurizing the carbon dioxide gas to obtain a compressed gas, and providing the compressed gas to the desulfurization step.
10. The carbon dioxide separation and recovery method according to any one of claims 1 to 4, wherein the raw material gas is a reduction furnace gas.
11. The carbon dioxide separation and recovery method according to claim 10, wherein the reduction furnace gas is blast furnace gas.
12. A method for producing methanol, comprising synthesizing hydrocarbons or methanol from carbon dioxide obtained using the carbon dioxide separation and recovery method described in any one of claims 1 to 4.