Method for separating and recovering carbon dioxide and method for producing methanol
By combining pressure swing adsorption with carbonyl sulfur hydrolysis and desulfurization processes, the problem of catalyst degradation caused by the coexistence of H2S and COS with CO2 in blast furnace gas was solved, and high-purity CO2 was efficiently separated and recovered for methanol synthesis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2024-10-21
- Publication Date
- 2026-04-10
AI Technical Summary
Sulfur compounds H2S and COS in blast furnace gas are adsorbed together with CO2 in the adsorption tower, leading to catalyst deterioration. Existing technologies make it difficult to effectively separate and recover high-purity CO2 for methanol synthesis.
The pressure swing adsorption method is combined with carbonyl sulfur hydrolysis and desulfurization processes. By hydrolyzing COS into H2S and CO2, high-purity CO2 is separated and recovered using catalysts such as aluminum, cobalt, and molybdenum, and dry desulfurizing agents such as iron and copper, while inhibiting catalyst deterioration.
It effectively separates and recovers high-purity CO2, reduces catalyst degradation, and improves the efficiency and product quality of methanol synthesis reaction.
Smart Images
Figure CN121843752A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for separating and recovering carbon dioxide and a method for manufacturing methanol. Background Technology
[0002] In recent years, efforts to prevent global warming have called for reductions in carbon dioxide (CO2) emissions. Iron and steel plants emit large quantities of byproduct gases, primarily blast furnace gas, as well as coke oven gas and converter gas. Blast furnace gas, in particular, is a major contributor to emissions. Although used as an energy source within the iron and steel plant, it contains significant amounts of CO2 and is directly emitted. Therefore, separating CO2 from blast furnace gas and utilizing it effectively is a crucial issue.
[0003] As an effective method for utilizing CO2, one example is the use of catalysts to convert CO2 into valuable substances such as methanol and methane. For instance, Patent Document 1 proposes a method for synthesizing methanol from a feed gas containing CO2 and hydrogen (H2) using a catalyst.
[0004] The catalysts used in the synthesis of methanol and methane described above deteriorate due to sulfur compounds such as hydrogen sulfide (H2S) and carbonyl sulfide (COS) in the blast furnace gas. Therefore, in order to effectively utilize the CO2 contained in the blast furnace gas, it is necessary to separate CO2 from the blast furnace gas and perform desulfurization.
[0005] As a method for separating CO2, pressure swing adsorption (PSA) is an example that utilizes the pressure dependence of the adsorption capacity in adsorbents such as zeolites. For instance, Patent Document 2 proposes a method for separating and recovering CO2 from a feed gas containing CO2 using the PSA method.
[0006] As described in Patent Document 2, a process for separating CO2 from reducing furnace gases such as blast furnace gas (containing CO2, carbon monoxide (CO), H2, nitrogen (N2), water (H2O), H2S, and COS) using the PSA method, and then synthesizing methanol using a catalyst, could be considered as follows: Figure 1 The process is shown below.
[0007] First, the raw material gas G01, such as the reduction furnace gas, is introduced into the dehumidification device 1, which is installed before the CO2 separation in the PSA unit 2, to dehumidify the raw material gas G01 and reduce its H2O concentration. This is because in the PSA process, when the H2O concentration in the raw material gas is high, the CO2 separation capacity will decrease significantly.
[0008] Next, the dehumidified feed gas G01 with reduced H2O concentration is introduced into PSA unit 2. In PSA unit 2, firstly in the adsorption process, the dehumidified feed gas G01 is introduced into the adsorption tower of PSA unit 2, so that CO2 is adsorbed by the adsorbent filled in the adsorption tower, and at the same time, non-adsorbed gas G02 containing non-adsorbed gas components that were not adsorbed by the adsorbent is discharged.
[0009] Subsequently, in the desorption process, the pressure inside the adsorption tower is reduced by pump 3A, causing the CO2 adsorbed on the adsorbent to desorb, and the gas containing CO2 is discharged from the adsorption tower as desorbed gas G03.
[0010] The discharged desorbed gas G03 is compressed by compressor 3B, mixed with H2 gas G04 and sent to methanol synthesis equipment 4, where methanol G05 is synthesized through the reaction of the following formula (1).
[0011]
[0012] Patent Document 1: Japanese Patent No. 7049075
[0013] Patent Document 2: Japanese Patent No. 6677181 Summary of the Invention
[0014] As mentioned above, in addition to the main gaseous components such as CO2, CO, and H2, blast furnace gas also contains sulfur-containing gaseous components such as H2S and COS from iron ore and coke. These H2S and COS are adsorbed onto the adsorbent in the adsorption tower along with CO2. Therefore, if blast furnace gas is used as feed gas G01, there is a problem that H2S and COS will be separated and recovered from feed gas G01 along with CO2, becoming impurities in the CO2 gas. If this desorbed gas G03 containing H2S and COS is introduced into the methanol synthesis unit 4 for the methanol synthesis reaction, it will degrade the catalyst used in the methanol synthesis reaction.
[0015] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a carbon dioxide separation and recovery method that can separate and recover carbon dioxide after removing hydrogen sulfide and carbonyl sulfide from a feed gas containing carbon dioxide, hydrogen sulfide and carbonyl sulfide.
[0016] [1] A method for separating and recovering carbon dioxide, which is a method for separating and recovering carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide and carbonyl sulfide by pressure swing adsorption, has the following characteristics:
[0017] The dehumidification process removes moisture from the aforementioned raw material gas to obtain dehumidified raw material gas, and
[0018] The carbon dioxide recovery process separates and recovers carbon dioxide gas from the aforementioned dehumidifying raw material gas using pressure swing adsorption.
[0019] The above-mentioned carbon dioxide separation and recovery methods also include:
[0020] The carbonyl sulfide hydrolysis process that hydrolyzes the aforementioned carbonyl sulfide with water to form hydrogen sulfide and carbon dioxide, and
[0021] Desulfurization process for separating hydrogen sulfide.
[0022] [2] According to the carbon dioxide separation and recovery method described in [1] above, the carbonyl sulfur hydrolysis process is located before the dehumidification process.
[0023] [3] According to the carbon dioxide separation and recovery method described in [2] above, the desulfurization process is located in the later stage of the carbon dioxide recovery process.
[0024] [4] According to the carbon dioxide separation and recovery method described in [2] above, the desulfurization process is located after the carbonyl sulfur hydrolysis process and before the carbon dioxide recovery process.
[0025] [5] According to the carbon dioxide separation and recovery method described in [1] above, the carbonyl sulfur hydrolysis step is located in the later stage of the carbon dioxide recovery step.
[0026] [6] According to the carbon dioxide separation and recovery method described in [5] above, a humidification step for adjusting the moisture content of the carbon dioxide gas is further provided in the latter part of the carbon dioxide recovery step and the former part of the carbonyl sulfide hydrolysis step.
[0027] [7] According to the carbon dioxide separation and recovery method described in [6] above, the above-mentioned humidity conditioning step is a water washing step of washing the above-mentioned carbon dioxide gas with water.
[0028] [8] According to the carbon dioxide separation and recovery method described in [6] above, the above-mentioned humidity conditioning step is a water vapor addition step of adding water vapor to the above-mentioned carbon dioxide gas.
[0029] [9] The carbon dioxide separation and recovery method according to any one of [1] to [8] above, wherein the catalyst used in the carbonyl sulfur hydrolysis step is a catalyst containing aluminum oxide.
[0030]
[10] The carbon dioxide separation and recovery method according to any one of [1] to [8] above, wherein the catalyst used in the carbonyl sulfur hydrolysis step is a catalyst containing one or both of the following: cobalt oxide or sulfide, and molybdenum oxide or sulfide.
[0031]
[11] The carbon dioxide separation and recovery method according to any one of [1] to
[10] above, wherein the desulfurizing agent used in the above desulfurization process is a dry desulfurizing agent, and the dry desulfurizing agent contains at least one selected from iron oxide, copper oxide and zinc oxide.
[0032]
[12] According to the carbon dioxide separation and recovery method described in
[11] above, at least two of the above-mentioned dry desulfurizing agents are used in the above-mentioned desulfurization process, and at least one dry desulfurizing agent contains iron oxide and at least one dry desulfurizing agent contains copper oxide.
[0033]
[13] The carbon dioxide separation and recovery method according to any one of [1] to
[12] above, further comprising a compression step of pressurizing the carbon dioxide gas to obtain compressed gas, and supplying the compressed gas to the desulfurization step.
[0034]
[14] The carbon dioxide separation and recovery method according to any one of [1] to
[13] above, wherein the raw material gas is a reduction furnace gas.
[0035]
[15] According to the carbon dioxide separation and recovery method described in
[14] above, the reduction furnace gas is blast furnace gas.
[0036]
[16] A method for producing methanol, wherein carbon dioxide obtained by any one of the carbon dioxide separation and recovery methods described in any one of [1] to
[15] is used to synthesize hydrocarbons or methanol.
[0037] According to the present invention, carbon dioxide after the removal of hydrogen sulfide and carbonyl sulfide can be separated and recovered from a feed gas containing carbon dioxide, hydrogen sulfide and carbonyl sulfide. Attached Figure Description
[0038] Figure 1 This is a flowchart illustrating an example of a conventional carbon dioxide separation and recovery method.
[0039] Figure 2 This is a flowchart illustrating a preferred example of the carbon dioxide separation and recovery method according to the present invention.
[0040] Figure 3 This is a flowchart illustrating a preferred example of a method for manufacturing methanol according to the present invention. Detailed Implementation
[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The carbon dioxide separation and recovery method according to the present invention is a method for separating and recovering carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide by pressure swing adsorption (PSA), comprising: a dehumidification step to remove moisture from the feed gas to obtain a dehumidified feed gas; and a carbon dioxide recovery step to separate and recover carbon dioxide gas from the dehumidified feed gas by PSA. Here, the method is characterized by including a carbonyl sulfide hydrolysis step in which carbonyl sulfide reacts with moisture to hydrolyze into hydrogen sulfide and carbon dioxide, and a desulfurization step for separating hydrogen sulfide.
[0042] The inventors have conducted in-depth research on a method for separating and recovering CO2 after removing H2S and COS from a feed gas containing CO2, H2S, and COS. The result is the discovery that COS, which is difficult to remove, can be pre-hydrolyzed to convert into H2S as shown in equation (2), and the resulting H2S is then desulfurized together with the original H2S in the feed gas. This allows CO2 after removing H2S and COS to be obtained from the feed gas, and the resulting CO2 gas can be introduced into the methanol synthesis unit 4 to synthesize methanol. In this process, the degradation of the catalyst used in the methanol synthesis reaction can be suppressed.
[0043]
[0044] Figure 2 The flowchart illustrates a preferred example of the carbon dioxide separation and recovery method according to the present invention. It should be noted that, in Figure 2 In, with Figure 1 The same reference numerals are used in the drawings showing the same configuration. Hereinafter, the same reference numerals will be used. Figure 2 The process shown illustrates the carbon dioxide separation and recovery method according to the present invention, but the present invention is not limited thereto.
[0045] First, the raw material gas G01 is introduced into the humidification equipment 5, and the H2O concentration of the raw material gas G01 is adjusted (humidification process). The raw material gas G01 is a gas containing CO2, H2S, and COS. Examples of such gases include by-product gases discharged from ironmaking plants. Examples of by-product gases include blast furnace gas, coke oven gas, converter gas, and other reduction furnace gases containing CO2, CO, N2, H2, H2S, and COS. This invention can effectively remove COS and H2S from the aforementioned blast furnace gas and recover CO2 gas, thereby reducing CO2 emissions.
[0046] The humidity conditioning equipment 5 is used to adjust the H2O concentration of the raw material gas G01. This humidity conditioning equipment 5 can be composed of a water washing device that washes the raw material gas G01 with water. In this case, the humidity conditioning process is constituted as a water washing process. During the water washing process, the H2O concentration of the raw material gas G01 can be adjusted by adjusting the water washing temperature. Furthermore, the water washing process can remove water-soluble gaseous components such as HCl and NH3 from the raw material gas G01.
[0047] Alternatively, the humidity conditioning equipment 5 can be configured as a steam addition device that adds water vapor to the raw material gas G01. In this case, the humidity conditioning process is configured as a steam addition process. In the steam addition device, the H2O concentration of the raw material gas G01 can be controlled by the flow rate of the water vapor.
[0048] Next, the raw material gas G01, whose H2O concentration has been adjusted in the humidification process, is introduced into the COS hydrolysis equipment 6. According to the above formula (2), the COS contained in the raw material gas G01 reacts with H2O and is hydrolyzed into H2S and CO2 (carbonyl sulfide hydrolysis process).
[0049] The COS hydrolysis device 6 can be constructed from a catalyst-packed tower filled with a catalyst that promotes the reaction of the above formula (2). The catalyst filled in can be a catalyst containing an oxide of aluminum (Al). Alternatively, the catalyst can contain one or both of the above-mentioned oxides or sulfides of cobalt (Co) and oxides or sulfides of molybdenum (Mo).
[0050] In this carbonyl sulfur hydrolysis process, the feed gas G01, containing COS and H2O, is circulated in the COS hydrolysis device 6 to hydrolyze the COS contained in the feed gas G01. From the viewpoint of preventing H2O condensation, the temperature of the COS hydrolysis device 6, such as the catalyst packed tower (i.e., the temperature of the catalyst inside the packed tower), is preferably set to 100°C or higher. Generally, H2S has a higher reactivity with dry desulfurizing agents than COS; by pre-converting it to H2S, the efficiency of the dry desulfurizing agent is improved.
[0051] Next, the raw material gas G01, which is converted from COS to H2S, is introduced into dehumidification equipment 1 to remove the moisture from the raw material gas G01, thus obtaining dehumidified raw material gas (dehumidification process).
[0052] The dehumidification device 1 can be configured, for example, as a dehumidification device that cools the raw material gas G01 to condense H2O for dehumidification. Alternatively, the dehumidification device 1 can also be configured as a desiccant-type device such as a packed adsorption tower filled with an adsorbent that adsorbs H2O, such as Al oxide, silicon (Si) oxide, or zeolite.
[0053] The dehumidification process is preferably carried out until the dew point of the raw material gas G01 is below 0°C, and more preferably below -20°C. This prevents a decrease in the amount of CO2 adsorbed by the adsorbent in the subsequent carbon dioxide recovery process.
[0054] Then, the dehumidified raw material gas G01 obtained in the dehumidification process is introduced into the PSA unit 2, and CO2 gas is separated and recovered from the dehumidified raw material gas G01 by the PSA method (carbon dioxide recovery process).
[0055] PSA unit 2 can be configured as an adsorption tower filled with an adsorbent such as zeolite that adsorbs CO2. In the adsorption process, by circulating the dehumidified feed gas G01 through the adsorption tower, CO2 is adsorbed onto the adsorbent, while the unadsorbed gas components are discharged from the adsorption tower as non-adsorbed gas G02. Then, in the desorption process, pump 3 is used to depressurize the interior of the adsorption tower, causing CO2 to desorb from the adsorbent, and the desorbed gas G03, containing the desorbed CO2, is separated and recovered. At this time, the pressure of the gas at the inlet of pump 3 is, for example, 1 kPa to 20 kPa, and the pressure of the gas at the outlet of pump 3 is, for example, 100 kPa or more. In this carbon dioxide recovery process, when the feed gas G01 is blast furnace gas, CO, N2, and H2 in the feed gas G01 are mainly separated into non-adsorbed gas G02, while CO2, H2S, COS, and H2O are mainly separated into desorbed gas G03.
[0056] The pressure during depressurization in the adsorption tower during the above desorption process is preferably 1 kPa to 20 kPa, and more preferably 5 kPa to 10 kPa.
[0057] Next, the desorbed gas GO3 is introduced into the desulfurization equipment 7 to separate the H2S contained in the desorbed gas GO3 (desulfurization process).
[0058] 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 desorbed gas GO3 in the desulfurizing agent packed tower, H2S can be desulfurized by being adsorbed by the desulfurizing agent.
[0059] Examples of dry desulfurizing agents include oxides of iron (Fe), oxides of copper (Cu), and oxides of zinc (Zn). Desulfurizing agents containing one or more of these oxides can be used.
[0060] In addition, it is preferable to use at least two dry desulfurizing agents, at least one of which is a desulfurizing agent containing Fe oxides, and at least one of which is a desulfurizing agent containing Cu oxides. Considering the combination of various desulfurizing agents and the order in which they are used, it is preferable to first use an inexpensive dry desulfurizing agent containing Fe oxides to remove H2S contained in the desorbed gas GO3, and then use a dry desulfurizing agent containing Cu oxides to remove the residual H2S and COS.
[0061] For desulfurization processes using at least two of the aforementioned desulfurizing agents, a number of desulfurizing agent packed towers, not less than the number of different types of desulfurizing agents, can be installed. Each packed tower is filled with desulfurizing agent, allowing the desorbed gas GO3 to flow sequentially through each tower, thereby achieving desulfurization of the desorbed gas GO3. For example, when using two dry desulfurizing agents, such as... Figure 2 As shown, two desulfurizing agent packed towers, 7A and 7B, are set up. Desulfurizing agent packed tower 7A is filled with a dry desulfurizing agent containing Fe oxides, and desulfurizing agent packed tower 7B is filled with a dry desulfurizing agent containing Cu oxides. Then, by allowing the desorbed gas GO3 to flow sequentially through desulfurizing agent packed towers 7A and 7B, the desorbed gas GO3 is desulfurized, resulting in desorbed gas GO3 with reduced H2S and COS concentrations, i.e., CO2 gas GO6.
[0062] In the above description, the COS hydrolysis device 6 is set in front of the dehumidification device 1, and the carbonyl sulfide hydrolysis process is carried out in front of the dehumidification process. However, it is not limited to this. It can also be configured such that the COS hydrolysis device 6 is set in the back of the PSA device 2, and the carbonyl sulfide hydrolysis process is carried out in the back of the carbon dioxide recovery process.
[0063] However, in the COS hydrolysis process, it is preferable to use feed gas G01 with an H2O concentration increased to 1% or more. To maintain the performance of the PSA unit 2, a dehumidification device 1 is installed, but there is no equipment to increase the H2O concentration downstream of the dehumidification device 1. Therefore, in the COS hydrolysis process, when the H2O concentration is low and COS cannot be fully hydrolyzed, COS that is difficult to react with the desulfurizing agent remains in the gas and may flow into the catalyst of the downstream desulfurization unit 7, leading to catalyst deterioration. On the other hand, the feed gas G01 after the water washing process can obtain an H2O concentration close to the vapor pressure at that temperature. For example, when the water washing process is carried out at 25°C, the H2O concentration of the feed gas G01 can easily reach 1% or more. Therefore, the feed gas G01 after the water washing process is suitable for COS hydrolysis. Therefore, as... Figure 2 As shown, it is preferable to place the COS hydrolysis device 6 in front of the dehumidification device 1, and to perform the carbonyl sulfur hydrolysis process in front of the dehumidification process.
[0064] When the COS hydrolysis device 6 is configured to be located downstream of the PSA unit 2, and the carbonyl sulfide hydrolysis process is performed downstream of the carbon dioxide recovery process, it is preferable to further install a humidity conditioning device 5 downstream of the PSA unit 2 and upstream of the COS hydrolysis device 6, and further perform a humidity conditioning 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 ensures that the COS contained in the desorbed gas GO3 is fully hydrolyzed.
[0065] In addition, Figure 2 In this configuration, the desulfurization equipment 7 is located downstream of the PSA unit 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 it is unnecessary to place the desulfurization equipment 7 upstream of the PSA unit 2. However, it is also possible to configure the desulfurization equipment 7 upstream of the PSA unit 2, and perform the desulfurization process upstream of the carbon dioxide recovery process. Furthermore, it is also possible to configure the desulfurization equipment 7 upstream of the PSA unit 2 and downstream of the COS hydrolysis equipment 6, and perform the desulfurization process downstream of the carbonyl sulfide hydrolysis process and upstream of the carbon dioxide recovery process.
[0066] However, from the viewpoint of suppressing carbon deposition (coking) from CO in the gas, gases with low CO concentrations are preferred. Therefore, it is preferable to install the desulfurization unit 7 downstream of the PSA unit 2, performing the desulfurization process downstream of the carbon dioxide recovery process. Furthermore, adsorbents such as zeolites used in the PSA process also adsorb H2S and COS. Therefore, by installing the desulfurization unit 7 downstream of the PSA unit 2, H2S and COS are concentrated on the desorbed gas GO3 side, which contains CO2 discharged from the PSA unit 2. The desorbed gas GO3 has a higher concentration of H2S and COS than the feed gas GO1, and its flow rate is lower, thus also increasing the desulfurization capacity and reducing the amount of H2S and COS escaping from the outlet of the desulfurization unit 7.
[0067] Figure 3 The flowchart illustrates a preferred example of a method for producing methanol according to the present invention. It should be noted that, in Figure 3 In the middle, to and Figure 2 The components shown are identical, and the same reference numerals are used in the accompanying drawings. Figure 3 The process shown is the same as Figure 2 The difference in the process shown is: in Figure 3 The process shown is configured such that, in addition to the COS hydrolysis process, a water-gas shift reaction process is also performed in the COS hydrolysis unit 16. Furthermore, in... Figure 3 The process shown is configured as follows: a compression step is performed, in which desorbed gas GO3 is introduced into compressor 3B, and the desorbed gas GO3 is pressurized to a pressure of 1000 kPa or higher to obtain compressed gas. Furthermore, in... Figure 3 The process shown is as follows: CO2 gas G06, after H2S and COS have been removed in the desulfurization process, is introduced into methanol synthesis unit 4 to produce methanol G05. The differences are explained below.
[0068] First, in the COS hydrolysis unit 16, for the water-gas shift reaction process, the humidity conditioning unit 5 consists of a humidity conditioning unit 5A for a water washing process and a humidity conditioning unit 5B for a water vapor addition process that adds water vapor G07 to the raw material gas G01. First, the raw material gas G01 is introduced into the humidity conditioning unit 5A for a water washing process 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 conditioning unit 5B, where water vapor is added to increase the H2O concentration. Then, the raw material gas G01 with the increased H2O concentration is introduced into the COS hydrolysis unit 16 to perform the carbonyl sulfide hydrolysis process and the water-gas shift reaction process. This improves the CO2 processing efficiency.
[0069] In the humidity conditioning device 5B, water vapor G07 is added to the feed gas G01. From the viewpoint of preventing carbon precipitation from the catalyst in the COS hydrolysis device 16, the molar ratio of H2O / CO in the feed gas G01 after the addition of water vapor G07 is preferably 1.0 or more, and more preferably 2.0 or more. Furthermore, since the water-gas shift reaction is an exothermic reaction, lower temperatures are more favorable for chemical equilibrium. Therefore, the temperature of the catalyst in the COS hydrolysis device 16 is preferably 200°C to 500°C, and more preferably 200°C to 400°C. Also, regarding the temperature of the feed gas G01 after the addition of water vapor G07, it is preferably 200°C to 500°C, and more preferably 200°C to 400°C.
[0070] Following the COS hydrolysis and water-gas shift reaction processes described above, a dehumidification process is performed using dehumidification equipment 1 to remove H2O from the feed gas G01, resulting in dehumidified feed gas G01. The dehumidification process is preferably carried out until the dew point of the feed gas G01 is below 0°C, more preferably below -20°C. Then, in the adsorption process, the dehumidified feed gas G01 is passed through a PSA unit 2 equipped with an adsorbent-packed tower filled with zeolite as the adsorbent, causing CO2 to be adsorbed onto the adsorbent, while simultaneously discharging non-adsorbed gas G02 containing unadsorbed non-adsorbed gas components. Then, in the desorption process, the internal pressure of the adsorption tower is reduced by pump 3A, causing CO2 to desorb from the adsorbent, and the gas containing CO2 is discharged from the adsorption tower as desorbed gas G03.
[0071] Next, the desorbed gas GO3 discharged from the adsorption tower is introduced into compressor 3B and pressurized. The pressure of the desorbed gas GO3 can be set to an appropriate value according to the subsequent reaction. In the upstream PSA unit 2, when synthesizing methanol, the pressure of the desorbed gas GO3 is preferably set to 1 MPa to 10 MPa by compressor 3B.
[0072] The desorbed gas G03 further flows through a desulfurizing agent packed tower 7A filled with a dry desulfurizing agent containing Fe oxides, and then flows through a desulfurizing agent packed tower 7B filled with a dry desulfurizing agent containing Cu oxides, thereby reducing 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. By using pressurized desorbed gas G03, an increase in desulfurization capacity and a promotion of the desulfurization reaction are expected, therefore it is preferred. To improve the desulfurization performance of the desulfurizing agent packed tower 7B, a dehumidification device 1 can be further installed upstream for a dehumidification process.
[0073] Then, H2 gas G04 is mixed with CO2 gas G06 and introduced into methanol synthesis unit 4, where methanol G05 is synthesized through the reaction described in formula (1) above. Since H2S and COS are removed from CO2 gas G06, which is the raw material for methanol G05, the deterioration of the catalyst used in the synthesis reaction of methanol G05 can be suppressed.
[0074] In the above description, although methanol G05 is produced in methanol synthesis unit 4, it can also be produced by manufacturing hydrocarbons. In this case, a hydrocarbon synthesis unit filled with a hydrocarbon synthesis catalyst can be used instead of methanol synthesis unit 4. For example, if the synthesized hydrocarbon is methane, a hydrocarbon synthesis unit can be used with the following configuration: a reaction vessel filled with a catalyst containing Ni is kept at 200°C to 400°C, and CO2 gas G06 and H2 gas G04 are circulated.
[0075] Industrial availability
[0076] According to the present invention, carbon dioxide after the removal of hydrogen sulfide and carbonyl sulfide can be separated and recovered from a feed gas containing carbon dioxide, hydrogen sulfide and carbonyl sulfide.
[0077] Symbol Explanation
[0078] 1. Dehumidification equipment
[0079] 2 Transformer
[0080] 3. 3A Pump
[0081] 3B compressor
[0082] 4. Methanol Synthesis Equipment
[0083] 5. 5A, 5B Humidity Control Equipment
[0084] 6.16 Carbonyl Sulfate Hydrolysis Equipment
[0085] 7. Desulfurization equipment
[0086] G01 Raw Material Gas
[0087] G02 Non-adsorbed gas
[0088] G03 Desorption Gas
[0089] G04 Hydrogen
[0090] G05 Methanol
[0091] G06 Carbon Dioxide Gas
[0092] G07 Water Vapor
Claims
1. A method for separating and recovering carbon dioxide, comprising separating and recovering carbon dioxide from a feed gas containing carbon dioxide, hydrogen sulfide, and carbonyl sulfide using pressure swing adsorption, comprising: The dehumidification process removes moisture from the raw material gas to obtain a dehumidified raw material gas. The carbon dioxide recovery process involves separating and recovering carbon dioxide gas from the dehumidifying raw material gas using pressure swing adsorption. The carbon dioxide separation and recovery method further includes: The carbonyl sulfide hydrolysis process involves reacting the carbonyl sulfide with water to hydrolyze it into hydrogen sulfide and carbon dioxide. The desulfurization process separates hydrogen sulfide.
2. The carbon dioxide separation and recovery method according to claim 1, wherein, The carbonyl sulfur hydrolysis process is located before the dehumidification process.
3. The carbon dioxide separation and recovery method according to claim 2, wherein, The desulfurization process is located after the carbon dioxide recovery process.
4. The carbon dioxide separation and recovery method according to claim 2, wherein, The desulfurization process is located after the carbonyl sulfur hydrolysis process and before the carbon dioxide recovery process.
5. The carbon dioxide separation and recovery method according to claim 1, wherein, The carbonyl sulfur hydrolysis process is located after the carbon dioxide recovery process.
6. The carbon dioxide separation and recovery method according to claim 5, wherein, The carbon dioxide recovery process is followed by a humidification process that adjusts the moisture content of the carbon dioxide gas. This process is located after the carbon dioxide recovery process and before the carbonyl sulfide hydrolysis process.
7. The carbon dioxide separation and recovery method according to claim 6, wherein, The humidity conditioning process is a water washing process that involves washing the carbon dioxide gas with water.
8. The carbon dioxide separation and recovery method according to claim 6, wherein, The humidity conditioning process is a water vapor addition process that adds water vapor to the carbon dioxide gas.
9. The carbon dioxide separation and recovery method according to any one of claims 1 to 8, wherein, The catalyst used in the carbonyl sulfur hydrolysis process is a catalyst containing aluminum oxide.
10. The carbon dioxide separation and recovery method according to any one of claims 1 to 8, wherein, The catalyst used in the carbonyl sulfur hydrolysis process is a catalyst containing one or both of the following: cobalt oxides or sulfides, and molybdenum oxides or sulfides.
11. The carbon dioxide separation and recovery method according to any one of claims 1 to 10, wherein, The desulfurizing agent used in the desulfurization process is a dry desulfurizing agent, which contains at least one selected from iron oxide, copper oxide and zinc oxide.
12. The carbon dioxide separation and recovery method according to claim 11, wherein, At least two of the dry desulfurizing agents are used in the desulfurization process, and at least one dry desulfurizing agent contains an iron oxide and at least one dry desulfurizing agent contains a copper oxide.
13. The carbon dioxide separation and recovery method according to any one of claims 1 to 12, wherein, The system further includes a compression step of pressurizing the carbon dioxide gas to obtain compressed gas, and supplying the compressed gas to the desulfurization step.
14. The carbon dioxide separation and recovery method according to any one of claims 1 to 13, wherein, The raw material gas is a reduction furnace gas.
15. The carbon dioxide separation and recovery method according to claim 14, wherein, The reducing furnace gas is blast furnace gas.
16. A method for producing methanol, comprising synthesizing hydrocarbons or methanol from carbon dioxide obtained by the carbon dioxide separation and recovery method according to any one of claims 1 to 15.