Gas separation apparatus and gas separation method

Abstract

A specific gas component included in a raw material gas is separated with good efficiency using a PSA method. A gas separation apparatus 11 that separates and recovers a gas component 1 from a raw material gas containing at least the gas component 1 and a gas component 2 by a pressure swing adsorption method includes an adsorption column 12 filled with an adsorbent that adsorbs and desorbs the gas component 1 and the gas component 2, in which the raw material gas is introduced into the adsorption column 12 to be adsorbed to the adsorbent, and the adsorption column 12 is depressurized to desorb the raw material gas adsorbed to the adsorbent. The gas separation apparatus 11 further includes a temperature measuring unit 26 that measures a temperature of the adsorbent, a temperature adjusting unit 31 that adjusts the temperature of the adsorbent, and a control unit 35 that controls the temperature adjusting unit 31 so that the temperature of the adsorbent becomes a target temperature. The target temperature is determined by comparing temperature change rates of effective adsorption amounts of the adsorbent with respect to the gas component 1 and the gas component 2.

Description

Technical Field

[0001] This invention relates to gas separation equipment and gas separation methods. Background Technology

[0002] Previously, pressure swing adsorption (PSA) was used as a method to separate specific gaseous components contained in a feed gas. PSA is a gas separation method that utilizes the fact that the amount of gas components adsorbed by the adsorbent varies depending on the type of gas and its partial pressure.

[0003] For example, Patent Document 1 discloses a gas separation method using the PSA method, which is "a gas separation and recovery method without a cleaning step, wherein the desorption step is divided into multiple time periods, and the desorbed gas is recovered in each of the time periods" ([Claim 1]). According to this method, "the concentration of the recovered gas can be increased without a cleaning step, thereby enabling the separation and recovery of high-concentration target gas components with low power consumption" (

[0013] ).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-114464 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In recent years, there has been a desire to efficiently separate specific gaseous components contained in feed gases.

[0009] For example, recently, CCU (Carbon Capture and Utilization) has attracted much attention for producing useful chemicals such as methanol from carbon dioxide (CO2) emitted in processes such as ironmaking. In this case, it is desirable to efficiently separate CO2 from blast furnace gases (raw material gases containing CO2, CO, and N2) emitted in processes such as ironmaking.

[0010] The present invention is made in view of the above aspects, and its object is to use the PSA method to efficiently separate specific gaseous components contained in the raw material gas.

[0011] Methods for solving problems

[0012] The inventors of this application conducted in-depth research and found that the above-mentioned objectives could be achieved by adopting the following configuration, thereby completing the present invention.

[0013] That is, the present invention provides the following [1] to

[16] .

[0014] [1] A gas separation device that uses pressure swing adsorption to separate and recover gas component 1 from a raw material gas containing at least gas component 1 and gas component 2. The gas separation device comprises: an adsorption tower filled with an adsorbent for adsorbing and desorbing gas component 1 and gas component 2; an inlet section for introducing the raw material gas into the adsorption tower so that it is adsorbed onto the adsorbent; a depressurization section for depressurizing the adsorption tower so that the raw material gas adsorbed onto the adsorbent is desorbed; a temperature measuring section for measuring the temperature of the adsorbent; a temperature regulating section for regulating the temperature of the adsorbent; and a control section for controlling the temperature regulating section to make the temperature of the adsorbent a target temperature, wherein the target temperature is determined by comparing the temperature change rate of the effective adsorption amount of gas component 1 and gas component 2 on the adsorbent.

[0015] [2] As described in [1] above, the target temperature is the temperature at which the temperature change rate of the effective adsorption amount of the gas component 1 on the adsorbent is less than the temperature change rate of the effective adsorption amount of the gas component 2 on the adsorbent.

[0016] [3] The gas separation device as described in [1] or [2] above, wherein the control unit determines the target temperature according to steps 1 to 3 below.

[0017] Step 1: For gas components 1 and 2, based on the adsorption isotherms of gas components i (i = 1, 2) at temperature T, calculate the change in equilibrium adsorption capacity corresponding to the pressure swing amplitude, i.e., the effective adsorption capacity ΔQ. i (T).

[0018] Step 2: Calculate the reference temperature T for gas component 1 and gas component 2. A With reference temperature T A The changing temperature T B Effective adsorption capacity ΔQ i (T) rate of temperature change X i (T A T B )=1-{ΔQ i (T B ) / ΔQ i (T A )}. Among them, T A <T B .

[0019] Step 3: For gas components 1 and 2, calculate the temperature change rate X of the effective adsorption amount. i (T A T BThe temperature change T that satisfies the following equation (1) is compared. B The target temperature is determined. Where 0 < α ≤ 1,

[0020] X1(T A T B )<α×X2(T A T B (1).

[0021] [4] The gas separation device as described in any one of [1] to [3] above, wherein the pressure reducing unit is provided with an exhaust line for exhausting the raw material gas desorbed from the adsorbent, and the exhaust line is branched into a branch line for exhausting the gas component 1 and a branch line for exhausting the gas component 2.

[0022] [5] The gas separation device as described in any one of [1] to [4] above, wherein the temperature regulating unit indirectly regulates the temperature of the adsorbent by regulating the temperature of the raw material gas.

[0023] [6] The gas separation device as described in [5] above, wherein the temperature regulating unit includes a heat exchanger capable of variably controlling at least one of the flow rate of the heat medium and the heat transfer area, and indirectly regulating the temperature of the adsorbent by adjusting the temperature of the raw material gas through the heat exchanger.

[0024] [7] The gas separation device as described in [6] above includes a gas circulation section that circulates a portion of the raw material gas from the outlet side of the heat exchanger to the inlet side of the heat exchanger.

[0025] [8] A gas separation method, which is a gas separation method for separating and recovering gas component 1 from a raw material gas containing at least gas component 1 and gas component 2 using pressure swing adsorption, wherein the raw material gas is introduced into an adsorption tower filled with an adsorbent for adsorbing and desorbing the gas component 1 and the gas component 2 and adsorbed onto the adsorbent, the pressure of the adsorption tower is reduced so as to desorb the raw material gas adsorbed onto the adsorbent, the temperature of the adsorbent is measured using a temperature measuring unit for measuring the temperature of the adsorbent, and a temperature regulating unit for controlling the temperature of the adsorbent is adjusted to achieve a target temperature, wherein the target temperature is determined by comparing the temperature change rate of the effective adsorption amount of the gas component 1 and the gas component 2 on the adsorbent.

[0026] [9] The gas separation method as described in [8] above, wherein the target temperature is the temperature at which the temperature change rate of the effective adsorption amount of the gas component 1 on the adsorbent is less than the temperature change rate of the effective adsorption amount of the gas component 2 on the adsorbent.

[0027]

[10] The gas separation method as described in [8] or [9] above, wherein the target temperature is determined according to steps 1 to 3 below.

[0028] Step 1: For gas components 1 and 2, based on the adsorption isotherms of gas components i (i = 1, 2) at temperature T, calculate the change in equilibrium adsorption capacity corresponding to the pressure swing amplitude, i.e., the effective adsorption capacity ΔQ. i (T);

[0029] Step 2: Calculate the reference temperature T for gas component 1 and gas component 2. A With reference temperature T A The changing temperature T B Effective adsorption capacity ΔQ i (T) rate of temperature change X i (T A T B )=1-{ΔQ i (T B ) / ΔQ i (T A )}. Among them, T A <T B .

[0030] Step 3: For gas components 1 and 2, calculate the temperature change rate X of the effective adsorption amount. i (T A T B The temperature change T that satisfies the following equation (1) is compared. B The target temperature is determined. Where 0 < α ≤ 1.

[0031] X1(T A T B )<α×X2(T A T B )…(1).

[0032]

[11] The gas separation method as described in any one of [8] to

[10] above, wherein the gas component 1 and the gas component 2 are adsorbed onto the adsorbent, and the gas component 1 and the gas component 2 adsorbed onto the adsorbent are desorbed separately according to the divided time period.

[0033]

[12] In the gas separation method described in any one of [8] to

[11] above, one cycle is defined as the process of adsorbing the raw material gas onto the adsorbent and then desorbing it. After at least five cycles, the temperature of the adsorbent is measured using the temperature measuring unit, and the temperature regulating unit is controlled to adjust the temperature of the adsorbent to a target temperature.

[0034]

[13] The gas separation method as described in any one of [8] to

[12] above, wherein the temperature of the adsorbent is the maximum value of the temperature amplitude measured by the temperature measuring unit.

[0035]

[14] The gas separation method as described in any one of [8] to

[13] above, wherein the temperature regulating unit indirectly regulates the temperature of the adsorbent by regulating the temperature of the raw material gas.

[0036]

[15] In the gas separation method described in

[14] above, the temperature regulating unit includes a heat exchanger that can variably control at least one of the flow rate of the heat medium and the heat transfer area, and the temperature of the adsorbent is indirectly regulated by adjusting the temperature of the raw material gas by using the heat exchanger.

[0037]

[16] In the gas separation method described above

[15] , a portion of the raw material gas at the outlet side of the heat exchanger is circulated to the inlet side of the heat exchanger.

[0038] Invention Effects

[0039] According to the present invention, specific gas components contained in the raw material gas can be efficiently separated using the PSA method. Attached Figure Description

[0040] [ Figure 1 This is a schematic diagram showing the gas separation device of the first embodiment.

[0041] [ Figure 2 This is a diagram illustrating an example of an adsorption isotherm of CO2 measured by varying the temperature.

[0042] [ Figure 3 This is a diagram illustrating an example of an adsorption isotherm of CO measured by varying the temperature.

[0043] [ Figure 4 This is a diagram illustrating an example of an adsorption isotherm of N2 measured by varying the temperature.

[0044] [ Figure 5 This is a diagram showing an example of the adsorption isotherms for gaseous component 1 (CO2) and gaseous component 2 (N2).

[0045] [ Figure 6 To show the reference temperature T A Change into changing temperature T B The figure shows an example of the adsorption isotherms of gas component 1 (CO2) and gas component 2 (N2) under the condition.

[0046] [ Figure 7 This is a schematic diagram showing the gas separation device of the second embodiment.

[0047] [ Figure 8 This is a schematic diagram illustrating the gas separation device of the third embodiment.

[0048] [ Figure 9 This is a schematic diagram showing the gas separation equipment used in Examples 1-2 and Comparative Example 1.

[0049] [ Figure 10 [Graph showing CO2 recovery rates for Examples 1-2 and Comparative Example 1] Detailed Implementation

[0050] [First Implementation]

[0051] The following is based on Figures 1-9 The gas separation equipment is described below. This description also serves as an explanation of the gas separation method.

[0052] Composition of Gas Separation Equipment

[0053] Figure 1 A schematic diagram of the gas separation device 11 according to the first embodiment is shown.

[0054] Gas separation equipment 11 is a device for separating and recovering gas component 1 from a feed gas containing at least gas component 1 (e.g., CO2) and gas component 2 (e.g., N2) using pressure swing adsorption (PSA).

[0055] The gas separation device 11 mainly consists of a vertical adsorption tower 12 for supplying gas to flow in an up-down direction. Inside the adsorption tower 12, there is an adsorbent (not shown) for adsorbing and desorbing gas components 1 and 2.

[0056] Figure 1 The gas separation device 11 shown is a so-called multi-tower type, with two adsorption towers 12 (adsorption tower 12a and adsorption tower 12b) arranged side by side. The number of adsorption towers 12 is not limited to two; it can be one or more.

[0057] At one end of adsorption tower 12 ( Figure 1 The upper end of the middle section is connected to an inlet pipe 13 for supplying raw material gas from the raw material gas supply source 61.

[0058] The raw material gas supply source 61 is, for example, a blast furnace that discharges blast furnace gas as raw material gas.

[0059] The inlet pipeline 13 introduces the raw material gas (a gas containing at least gas component 1 and gas component 2) into the adsorption tower 12 so that it is adsorbed by the adsorbent. An on / off valve 21 is provided midway through the inlet pipeline 13. The inlet pipeline 13 constitutes the inlet section.

[0060] On the other end of adsorption tower 12 ( Figure 1 The lower end of the adsorption tower 12 is connected to an exhaust gas pipeline 14. The exhaust gas is the raw gas that is introduced into the adsorption tower 12 but is not adsorbed by the adsorbent. The exhaust gas is discharged through the exhaust gas pipeline 14. An on / off valve 22 is provided in the middle of the exhaust gas pipeline 14.

[0061] Upstream of the on / off valve 22, in the exhaust gas pipeline 14, there is a desorbed gas exhaust pipeline 15.

[0062] The desorption gas exhaust line 15 is connected to the vacuum pump 18. By driving the vacuum pump 18, the internal pressure of the adsorption tower 12 is reduced, and the raw material gas adsorbed on the adsorbent is desorbed. The raw material gas desorbed from the adsorbent (desorbed gas) is exhausted through the desorption gas exhaust line 15. An on / off valve 23 is provided on the upstream side of the desorption gas exhaust line 15, above the vacuum pump 18.

[0063] The desorption gas exhaust line 15 is branched on the downstream side (emission side of vacuum pump 18) of vacuum pump 18, and is provided with branch line 16 and branch line 17.

[0064] On branch line 16 and branch line 17, on-off valve 24 and on-off valve 25 are respectively provided.

[0065] Among the gas components 1 and 2 contained in the raw material gas, a gas containing, for example, gas component 2 that is not expected to be recovered (impurity gas) is vented via branch line 16. On the other hand, a gas containing gas component 1 that is expected to be recovered (recovered gas) is vented via branch line 17.

[0066] The desorption gas exhaust line 15, branch line 16, branch line 17 and vacuum pump 18 constitute the pressure reducing section.

[0067] The adsorption tower 12 is provided with a temperature measuring unit 26 for measuring the temperature of the adsorbent filled inside the adsorption tower 12.

[0068] The temperature measuring unit 26 is not particularly limited, and may be, for example, a thermocouple. If the temperature measuring unit 26 is a thermocouple, a sheath (not shown) for the thermocouple, which reaches the interior of the adsorption tower 12, may also be provided on the outer periphery of the adsorption tower 12. By inserting the thermocouple into this sheath, the temperature of the adsorbent filling the adsorption tower 12 can be easily measured.

[0069] Multiple temperature measuring units 26 can also be set in each adsorption tower 12. For example, Figure 1 Temperature measuring units 26a and 26b are distributed along the vertical direction of the adsorption tower 12. This allows for accurate measurement of the adsorbent temperature.

[0070] A temperature regulating unit 31 is provided midway through the inlet pipeline 13 from the raw material gas supply source 61 to the adsorption tower 12.

[0071] There are no particular limitations on the temperature regulation unit 31. For example, a known heater such as an electric heater, which is an electric heating device, can be used. As a specific example, a jacketed heater that covers the outer periphery of the inlet pipe 13 can be cited.

[0072] The temperature control unit 31 regulates the temperature of the raw material gas introduced into the adsorption tower 12 by heating the raw material gas flowing through the inlet pipeline 13. Thus, for example, at a reference temperature T... A The temperature of the raw gas (e.g., 25°C) is increased, becoming a temperature change T. B (T A <T B ).

[0073] At this point, the initial temperature of the adsorbent in adsorption tower 12 is also the reference temperature T. A The temperature T changes B The raw gas is introduced into adsorption tower 12 and adsorbed and desorbed by the adsorbent, thus reaching the reference temperature T. A The adsorbent is also heated and gradually becomes a variable temperature T B .

[0074] Thus, by adjusting the temperature of the raw material gas introduced into the adsorption tower 12, the temperature of the adsorbent filling the adsorption tower 12 is indirectly adjusted.

[0075] It should be noted that the temperature control unit 31 is not limited to the example described above.

[0076] For example, if the adsorption tower 12 is small, a jacketed heater can be installed as a temperature control unit 31 on the outer periphery of the adsorption tower 12. In this case, the adsorbent filled inside the adsorption tower 12 is heated from the outer periphery of the adsorption tower 12. However, in this case, if the inner diameter of the adsorption tower 12 is large, poor heat transfer is likely to occur, and it may be difficult to heat the adsorbent uniformly up to the center of the adsorption tower 12.

[0077] In contrast, according to the example above (an example of indirectly adjusting the temperature of the adsorbent by adjusting the temperature of the raw material gas), the raw material gas is also introduced into the center of the adsorption tower 12, so the adsorbent can be heated in the same way up to the center of the adsorption tower 12.

[0078] As will be discussed later, even small temperature changes of around 15°C can sometimes significantly alter the equilibrium adsorption capacity of the adsorbent (see [link to relevant documentation]). Figures 2-4 Therefore, the adsorbent is preferably heated in the same way.

[0079] A control unit 35 is connected to the temperature regulation unit 31. As an example, the control unit 35 is a commercially available PC (personal computer).

[0080] Under the control of the control unit 35, the temperature regulating unit 31 is driven to rise to the desired temperature. In this way, the raw material gas flowing from the inlet pipe 13 is heated to the desired temperature.

[0081] <Adsorption Isotherm>

[0082] Figure 2 , Figure 3 and Figure 4 This is a diagram illustrating an example of adsorption isotherms for CO2, CO, and N2 measured by varying the temperature.

[0083] Figures 2-4 The adsorption isotherms are adsorption isotherms measured using 13X zeolite as the adsorbent (adsorption isotherms when each gas component is adsorbed and desorbed from 13X zeolite).

[0084] Figures 2-4 In this diagram, the temperature T used to measure the adsorption isotherm is varied in increments of 15°C within the range of 10–70°C. The adsorption isotherm represents the relationship between pressure and equilibrium adsorption amount Q, with the horizontal axis representing pressure (partial pressure) and the vertical axis representing equilibrium adsorption amount Q.

[0085] If Figures 2-4 In comparison, the adsorption capacity of CO2 is about one order of magnitude greater than that of CO and N2.

[0086] CO2, with its strong adsorption capacity, is rapidly adsorbed into the fine pores of the adsorbent under low pressure, resulting in a relatively nonlinear slope of the adsorption isotherm at low pressure. CO2 hardly desorbs under high pressure, but desorbs rapidly when the pressure is reduced to low pressure.

[0087] On the other hand, the adsorption isotherms of N2 and CO, which have weaker adsorption forces, are linear over a wider pressure range compared to CO2. N2 and CO desorb during the transition from high pressure to low pressure.

[0088] An adsorption isotherm is a graph showing the relationship between pressure P and equilibrium adsorption amount Q at a given temperature T, such as... Figures 2-4 As shown, the higher the temperature T, the smaller the equilibrium adsorption capacity Q becomes. Furthermore, the effective adsorption capacity ΔQ corresponding to the same pressure swing also changes accordingly; the higher the temperature T, the smaller the effective adsorption capacity ΔQ becomes.

[0089] For convenience, the following explanation will be based on the case where gas component 1 is carbon dioxide (CO2) and gas component 2 is nitrogen (N2).

[0090] Figure 5 This is a diagram illustrating an example of the adsorption isotherms for gaseous component 1 (CO2) and gaseous component 2 (N2).

[0091] In pressure swing adsorption (PSA), the phenomenon that the equilibrium adsorption capacity Q of the adsorbent changes with pressure swing is utilized. The change in the equilibrium adsorption capacity Q (also abbreviated as "adsorption capacity Q") is also called the effective adsorption capacity ΔQ. For example... Figure 5 As shown, even with the same pressure swing amplitude, the effective adsorption capacity ΔQ varies depending on the gas composition. i (i = 1, 2).

[0092] Using the effective adsorption capacity ΔQ1(ΔQ) of gas component 1 (CO2) CO2 The effective adsorption capacity ΔQ2 (ΔQ) of gas component 2 (N2) is greater than that of gas component 2 (N2). N2 The adsorbent is a gaseous component (CO2). Therefore, gaseous component 1 can be separated using the PSA method.

[0093] It should be noted that the adsorbent is not limited to 13X zeolite; any substance that exhibits an adsorption isotherm of the same shape as described above is acceptable. For example, other adsorbents such as ZSM-5 can also be used.

[0094] <Gas Separation Based on PSA Method>

[0095] For Figure 1 The method for separating and recovering gas component 1 from a feed gas containing at least gas component 1 and gas component 2 using pressure swing adsorption (PSA) in the gas separation device 11 shown will be described.

[0096] First, open the on / off valve 21 of the inlet pipeline 13 to introduce raw material gas from the raw material gas supply source 61 into the adsorption tower 12 via the inlet pipeline 13. Then, close the on / off valve 21.

[0097] Thus, the raw material gas is adsorbed by the adsorbent filled inside the adsorption tower 12.

[0098] More specifically, such as Figure 1 As shown, gas component 1, which has a strong adsorption capacity, is adsorbed in the region of adsorption tower 12 near the inlet (the connection between the inlet pipeline 13 and adsorption tower 12). On the other hand, gas component 2, which has a weak adsorption capacity, is adsorbed in the region of adsorption tower 12 away from the inlet.

[0099] At this time, the on / off valve 23 of the desorbed gas exhaust line 15 is closed, and the on / off valve 22 of the exhaust gas line 14 is opened in advance. As a result, the raw material gas (exhaust gas) that has not been adsorbed by the adsorbent is exhausted through the exhaust gas line 14.

[0100] It should be noted that, as Figure 1 As shown, temperature measuring units 26a and 26b can also be provided in the regions where gas component 1 is adsorbed and the regions where gas component 2 is adsorbed, respectively.

[0101] like Figure 1 As shown, when the raw material gas (gas component 1 and gas component 2) is distributed inside the adsorption tower 12, the on / off valve 22 of the exhaust gas pipeline 14 and the on / off valve 25 of the branch pipeline 17 are closed, and the on / off valve 23 of the desorbed gas exhaust pipeline 15 and the on / off valve 24 of the branch pipeline 16 are opened.

[0102] Furthermore, by driving the vacuum pump 18, the depressurization inside the adsorption tower 12 is initiated.

[0103] Therefore, firstly, the impurity gas containing gas component 2 with low adsorption capacity (for convenience, it is also referred to as "gas component 2") is desorbed from the adsorbent and discharged through the desorbed gas exhaust line 15 and the branch line 16 (first time period).

[0104] At this point, gas component 2 does not pass through the area where gas component 1 is adsorbed and is desorbed from the adsorbent. Therefore, the partial desorption of gas component 1 from the adsorbent and its subsequent exhaust can be prevented.

[0105] Next, close the on / off valve 24 of branch line 16 and open the on / off valve 25 of branch line 17. Then, drive the vacuum pump 18 to reduce the pressure inside the adsorption tower 12.

[0106] Therefore, the recovered gas containing gas component 1 with high adsorption capacity (for convenience, it is also simply referred to as "gas component 1") is desorbed from the adsorbent and discharged through the desorbed gas exhaust line 15 and branch line 17 (second time period). In the second time period, the pressure inside the adsorption tower 12 can be reduced more than in the first time period. In this way, gas component 1 is separated and recovered.

[0107] Thus, in the gas separation device 11, gas component 1 and gas component 2 can be recovered separately from different branch pipelines according to the divided time periods.

[0108] It should be noted that in adsorption tower 12, a portion of the desorption gas from other adsorption towers can also be used as a cleaning gas, a process known as cleaning.

[0109] Specifically, for example, a portion of the high-purity gas component 1 (CO2) desorbed from one adsorption tower 12a is used to expel gas component 2 (N2) from other adsorption towers 12b.

[0110] Next, as based on Figures 2-4 As explained, the higher the temperature T becomes, the smaller the equilibrium adsorption amount Q becomes, and the effective adsorption amount ΔQ corresponding to the same pressure swing amplitude also becomes smaller.

[0111] Next, the temperature regulating unit 31 is activated to raise the temperature of the adsorbent filled in the adsorption tower 12 from the reference temperature T. A (e.g., 25°C) becomes the reference temperature T. A High temperature variation T B (e.g., 70°C). Therefore, gas component 2 is more easily desorbed from the adsorbent during the first time period. Alternatively, before the first time period, gas component 2 is not adsorbed by the adsorbent and is easily discharged as exhaust gas.

[0112] However, if the temperature of the adsorbent is excessively increased, the effective adsorption capacity of gas component 1 becomes too small. In this case, gas component 1 also becomes easily desorbed during the first time period (or is easily discharged as exhaust gas before the first time period), which is not preferable.

[0113] Next, set the target temperature and adjust it so that the temperature of the adsorbent becomes the target temperature.

[0114] The target temperature is determined by comparing the temperature change rate of the effective adsorption amount of gas component 1 and gas component 2 on the adsorbent.

[0115] The adsorption isotherm of N2 shows a decreasing slope with increasing temperature over a wide pressure range (see [reference]). Figure 4 That is, regarding the effective adsorption capacity of N2 ΔQ N2In general, the effective adsorption capacity of CO tends to decrease with increasing temperature, exhibiting a high temperature dependence (large rate of temperature change). ΔQ CO The same applies (see also) Figure 3 ).

[0116] On the other hand, regarding the CO2 adsorption isotherm, as the temperature increases, the slope changes little under high pressure (shifting almost parallel downwards), while the slope decreases significantly under low pressure (e.g., below 10 kPa) (see...). Figure 2 ).

[0117] However, since reducing the pressure inside the adsorption tower 12 to a vacuum state results in poor operating efficiency of the vacuum pump 18, desorption is usually carried out under high pressure (e.g., above 10 kPa). In this case, even if the temperature increases, the decrease in the slope of the adsorption isotherm is small.

[0118] That is, regarding the effective adsorption capacity of CO2 ΔQ CO2 In this respect, even if the temperature is increased, it is not easy to reduce, and the temperature dependence is small (the temperature change rate is small).

[0119] Considering the difference in effective adsorption capacity ΔQ, the target temperature is set, for example, to achieve an effective adsorption capacity ΔQ1(ΔQ) for gas component 1 (CO2). CO2 The temperature change rate of component 2 (N2) is less than the effective adsorption capacity ΔQ2 (ΔQ) of gas component 2 (N2). N2 The rate of temperature change.

[0120] Therefore, under the condition that the relationship ΔQ1>ΔQ2 is maintained, the difference becomes larger, and gas component 1 can be separated more easily using the PSA method.

[0121] Specifically, the target temperature is determined, for example, by following steps 1 to 3.

[0122] Step 1: For gas components 1 and 2, based on the adsorption isotherm of gas component i (i = 1, 2) at temperature T, calculate the change in equilibrium adsorption capacity corresponding to the pressure swing amplitude, i.e., the effective adsorption capacity ΔQ. i (T). Also, the adsorption pressure (partial pressure) and desorption pressure (partial pressure) of gas component i at temperature T should be appropriately referenced.

[0123] The pressure variation range is appropriately determined according to each gas component i, which can be the same or different.

[0124] Step 2: Calculate the reference temperature T for gas composition 1 and gas composition 2. A With reference temperature T A The changing temperature T B Effective adsorption capacity ΔQ i (T) rate of temperature change Xi (T A T B )=1-{ΔQ i (T B ) / ΔQ i (T A )}. Among them, T A <T B .

[0125] Reference temperature T A There are no special limitations; for example, any temperature selected from the range of room temperature (5 to 35°C).

[0126] Step 3: For gas components 1 and 2, calculate the temperature change rate X of the effective adsorption amount. i (T A T B The temperature change T that satisfies the following equation (1) is compared. B The target temperature is determined. Where 0 < α ≤ 1. Specifically, α is, for example, 0.5.

[0127] X1(T A T B )<α×X2(T A T B (1)

[0128] Figure 6 To show the reference temperature T A Change into changing temperature T B The figure shows an example of the adsorption isotherms of gas component 1 (CO2) and gas component 2 (N2) under the condition.

[0129] Figure 6 In the middle, due to ΔQ CO2 (T A ): ΔQ CO2 (T B ) = 1:0.9, and ΔQ N2 (T A ): ΔQ N2 (T B = 1:0.5, therefore, the above equation (1) is satisfied when calculated in the following manner.

[0130] X CO2 (T A T B )=1-{ΔQ CO2 (T B ) / ΔQ CO2 (T A )}=0.1

[0131] X N2 (T AT B )=1-{ΔQ N2 (T B ) / ΔQ N2 (T A )}=0.5

[0132] X CO2 (T A T B )<α×X N2 (T A T B )

[0133] In the case where the raw gas contains other gas components (gas component 3, gas component 4, etc.) besides gas component 1 and gas component 2, respectively, X1(T) must also be satisfied. A T B )<α×X3(T A T B ), X1(T A T B )<α×X4(T A T B The target temperature is determined by methods such as (e.g., [missing information]).

[0134] In other words, other gas components are considered as another gas component 2, and the target temperature is determined in the same way as the above equation (1) for this other gas component 2.

[0135] Temperature change T B (Target temperature) can meet T A <T B The range is appropriately set according to the type of adsorbent and gas.

[0136] On the other hand, if T B If it is too high, then for example, the effective adsorption capacity ΔQ1(ΔQ) of gas component 1 (CO2) will be reduced. CO2 If the size becomes too small, the required amount of adsorbent increases, resulting in the adsorption tower 12 sometimes becoming too large. From the point of view, to avoid this, for example, in the case of using 13X zeolite as the adsorbent, T... B Preferably below 100°C.

[0137] The temperature change in the effective adsorption capacity ΔQ varies depending on the type of adsorbent. Therefore, the change in temperature T... B The upper limit should be set appropriately, taking into account factors such as the type of adsorbent, the cost of the adsorbent, and the size limitations of the adsorption tower.

[0138] There are no particular limitations on the subject that determines such a target temperature.

[0139] For example, the control unit 35 can perform calculations and determine the target temperature based on programs or by receiving operations from the operator of the gas separation device 11.

[0140] Alternatively, the operator of the gas separation device 11 can use other computers to determine the target temperature and input the determined target temperature into the control unit 35.

[0141] Then, the control unit 35 drives the temperature regulating unit 31 to control the temperature based on the determined target temperature.

[0142] Here, one cycle is defined as the process of the feed gas being adsorbed onto the adsorbent and then desorbed.

[0143] More specifically, one cycle is defined as the process of introducing the raw material gas into the adsorption tower 12, closing the on / off valve 21, and then exhausting the raw material gas (desorbed gas) from the adsorption tower 12 through the desorbed gas exhaust line 15.

[0144] Regarding the temperature of the adsorbent packed in the adsorption tower 12, there is a possibility that it changes compared to before the introduction (adsorption) of the feed gas. Therefore, after at least 5 cycles, the temperature of the adsorbent is measured using the temperature measuring unit 26. As a result, the temperature of the adsorbent is stabilized, and accurate temperature measurement is possible. Then, the temperature regulating unit 31 is controlled to adjust the temperature of the adsorbent to the target temperature.

[0145] Regarding the temperature of the adsorbent, even if the number of cycles reaches a certain level, it may sometimes fluctuate slightly due to the heat of adsorption and desorption of the feed gas.

[0146] Typically, the heat of adsorption is exothermic, while the heat of desorption is endothermic. Therefore, the temperature of the adsorbent is highest after the adsorption process is completed and lowest after the desorption process is completed.

[0147] The purity of gas component 1 in the desorbed gas is greatly affected by the desorption behavior of the raw material gas in the initial stage of the desorption process when a large amount of gas component 2 is desorbed (i.e., immediately after the adsorption process is completed).

[0148] That is, for example, in order to obtain a high purity recovered gas of gas component 1 in the second time period mentioned above, it is preferable to appropriately adjust the temperature of the adsorbent in the first time period mentioned above (including the initial stage of the desorption process, i.e., immediately after the adsorption process is completed) so that a large amount of gas component 2 is desorbed.

[0149] Therefore, the temperature measured by the temperature measuring unit 26 is preferably the temperature immediately after the adsorption process, which uses the highest temperature of the adsorbent, that is, the maximum value of the temperature amplitude measured by the temperature measuring unit.

[0150] [Second Implementation]

[0151] Figure 7 This is a schematic diagram illustrating the gas separation device 11a according to the second embodiment.

[0152] For parts that are the same as in the first embodiment, the same reference numerals are used, and the description is omitted.

[0153] The temperature control unit 41 of the gas separation device 11a includes a heat exchanger 42 disposed in the middle of the inlet pipeline 13 through which the raw material gas flows.

[0154] The heat exchanger 42 is connected to the heat medium source 43 via a heat medium pipeline 45. A pump 44 and a plurality of on / off valves 46 are provided on the heat medium pipeline 45. Opening the on / off valves 46 drives the pump 44, thereby allowing the heat medium (not shown) to flow from the heat medium source 43 into the heat exchanger 42 via the heat medium pipeline 45.

[0155] Thus, the raw material gas flowing from the inlet pipeline 13 undergoes heat exchange in the heat exchanger 42, and the temperature is regulated.

[0156] Examples of heat transfer media include liquid heat transfer media such as warm water and gaseous heat transfer media such as exhaust gas, which can be appropriately selected according to the specifications of the heat exchanger 42. As will be described later, low-temperature heat transfer media may also be used. The temperatures of the heat transfer media and the raw material gas are appropriately measured by installing thermocouples (not shown) in the heat exchanger 42.

[0157] As described below, heat exchanger 42 can variably control at least one of the flow rate of the heat medium and the heat transfer area.

[0158] First, such as Figure 7 As shown, a flow regulating valve 47 is provided upstream of the heat exchanger 42 in the heat medium pipeline 45. The flow regulating valve 47 can variably control the flow rate of the heat medium flowing through the heat exchanger 42.

[0159] In addition, such as Figure 7 As shown, a bypass 48, which does not pass through the heat exchanger 42, is connected to the heat medium line 45 via an on / off valve 49. By opening the on / off valve 49, a portion of the heat medium flowing through the heat medium line 45 can bypass the heat exchanger 42.

[0160] Thus, for example, even when it is difficult to control the flow rate of the heat medium using the flow regulating valve 47, the flow rate of the heat medium flowing through the heat exchanger 42 can be variably controlled.

[0161] In addition, the heat medium pipeline 45 flowing from the heat exchanger 42 is divided into multiple branches. Figure 7 As an example, the diagram illustrates heat medium pipelines 45a and 45b.

[0162] By opening and closing the on / off valve 46, it is possible to appropriately select the state in which the hot medium flows only through the hot medium pipeline 45a or the hot medium pipeline 45b, or the state in which the hot medium flows through both the hot medium pipeline 45a and the hot medium pipeline 45b.

[0163] Thus, in the heat exchanger 42, a surface (heat transfer surface) is divided to transfer heat to the raw material gas flowing through the inlet pipe 13, and its area (heat transfer area) can be variably controlled.

[0164] Next, as described above, the temperature regulating unit 31 in the first embodiment (see...) Figure 1 For example, consider electric heating devices such as electric heaters.

[0165] However, the temperature changes in the adsorption isotherms of CO2, N2, etc., occur at low temperatures, around 100°C (see [reference needed]). Figures 2-4 Therefore, it can be said that using an electric heating device with low energy conversion efficiency from electricity to heat is not efficient.

[0166] If the temperature is around 100°C or below, then warm wastewater generated in factories or similar facilities can be used as a heat transfer medium to heat the raw material gas (or even the adsorbent) through its low-temperature heat dissipation.

[0167] Therefore, in the second embodiment, a heat exchanger 42 capable of adjusting the temperature of the raw material gas using a heat medium is used. This allows for the effective utilization of unused exhaust heat, resulting in high economic efficiency.

[0168] It should be noted that in typical heat exchangers, the flow rate of the heat medium and the heat transfer area are designed to be constant, making it difficult to control the temperature of the raw gas.

[0169] Therefore, in the second embodiment, a heat exchanger 42 capable of controlling at least one of the heat medium flow rate and the heat transfer area is used. Thus, even in cases where, for example, the temperature of the heat medium is not constant, the temperature of the raw material gas can be adjusted.

[0170] [Third Implementation]

[0171] Figure 8 This is a schematic diagram illustrating the gas separation device 11b of the third embodiment.

[0172] For parts that are the same as in the first to second embodiments, the same reference numerals are used, and the description is omitted.

[0173] The gas separation device 11b has a gas circulation section 51 around the temperature regulation section 41.

[0174] The gas circulation unit 51 has a circulation line 52 connecting the outlet side of the heat exchanger 42 in the inlet line 13 to the inlet side. A pump 53 is arranged midway through the circulation line 52. By driving the pump 53, a portion of the feed gas at the outlet side of the heat exchanger 42 is circulated to the inlet side of the heat exchanger 42.

[0175] For example, it is also believed that the heat transfer area of ​​heat exchanger 42 can be variably controlled (see Figure 7 This is a difficult situation in terms of design. In this case, by repeating such a cycle, the raw material gas repeatedly flows through the heat exchanger 42, thus achieving the same effect as increasing the heat transfer area of ​​the heat exchanger 42.

[0176] Example

[0177] The present invention will be specifically described below with examples. However, the present invention is not limited to the examples described below.

[0178] <Gas Separation Equipment>

[0179] First, based on Figure 9 The gas separation apparatus 11c used in Examples 1-2 and Comparative Example 1 described below will be explained.

[0180] Figure 9 This is a schematic diagram illustrating the gas separation device 11c used in Examples 1-2 and Comparative Example 1. For comparison with... Figure 1 , Figure 7 and Figure 8 The same parts as those in the first to third embodiments described herein are given the same reference numerals and are omitted from the description.

[0181] like Figure 9 As shown, a temperature regulating unit 31, which serves as an electric heater, is provided on the inlet pipeline 13 located on the inlet side of the adsorption tower 12 and on the outer periphery of the adsorption tower 12. The temperature regulating unit 31 can control the temperature of the raw material gas and the adsorbent 30 flowing through the inlet pipeline 13.

[0182] The temperature measuring unit 26 is a thermocouple. In the adsorption tower 12, there is a sheath tube 27 that reaches the inside of the adsorption tower 12. By inserting the temperature measuring unit 26 (thermocouple) into the sheath tube 27, the temperature of the adsorbent 30 filled inside the adsorption tower 12 can be measured.

[0183] <Example 1>

[0184] Using gas cylinders and mass flow controllers (neither shown), a mixture of four components—22% CO2, 24% CO, 49% N2, and 5% H2—was prepared to simulate blast furnace gas emitted from an ironmaking plant and used as the feed gas.

[0185] As a small-scale adsorption tower 12, an SUS column with an inner diameter of 40 mm and a main body length of 250 mm was used. 190 g of 13X zeolite (φ1.5 mm particles) was filled inside the adsorption tower 12 as adsorbent 30.

[0186] By driving the temperature regulating unit 31 (electric heater), the temperature of the adsorbent 30 is increased from the reference temperature T. A (25℃) Heat to the change temperature T, which is the target temperature. B (90℃). This target temperature is determined in advance according to steps 1 to 3 above, and satisfies equation (1) above.

[0187] The temperature of the adsorbent 30 is determined using a temperature measuring unit 26 (thermocouple) inserted into the sheath 27. More specifically, it is determined based on the maximum value of the obtained temperature amplitude data.

[0188] In this state, the raw material gas is introduced into the adsorption tower 12 through the inlet pipeline 13 at a flow rate of 5.4 NL / min and a pressure of 151 kPa, where it is adsorbed onto the adsorbent 30. A portion of the raw material gas is not adsorbed onto the adsorbent 30 and is instead discharged as waste gas from the exhaust pipeline 14.

[0189] Then, vacuum pump 18 is used to reduce the pressure inside adsorption tower 12 to 6 kPa, thereby desorbing the raw material gas adsorbed on adsorbent 30. The total time for each cycle of adsorption and desorption is set to 200 seconds (adsorption cycle: 100 seconds, desorption cycle: 100 seconds).

[0190] Thus, the feed gas desorbed from adsorbent 30 (desorbed gas) is recovered as the recovered gas. The CO2 concentration of the recovered gas is determined using a gas analyzer (not shown).

[0191] The CO2 recovery rate is calculated based on the CO2 concentrations of the recovered gas and the feed gas. The results are presented below. Figure 10 The image.

[0192] By controlling the on / off valves 25 and 24, the ratio of the flow time t1 of the recovered gas flowing from branch line 17 to the flow time t2 of the impurity gas flowing from branch line 16 (gas flow time ratio t1 / t2) is varied. Thus, using a gas analyzer (not shown), the adjustment is made so that the final gas CO2 concentration is 90% by volume.

[0193] <Example 2>

[0194] The target temperature is set to 60℃. This target temperature is determined in advance according to steps 1 to 3 above and satisfies equation (1) above.

[0195] In addition, the recovered gas was recovered in the same manner as in Example 1, and the CO2 recovery rate was determined. The results are shown below. Figure 10 The image.

[0196] <Comparative Example 1>

[0197] The temperature control unit 31 (electric heater) is not driven. That is, the temperature of the adsorbent 30 is maintained at the reference temperature T. A (25℃) state.

[0198] In addition, the recovered gas was recovered in the same manner as in Example 1, and the CO2 recovery rate was determined. The results are shown below. Figure 10 The image.

[0199] <Summary of Evaluation Results>

[0200] Figure 10 A graph showing the CO2 recovery rates of Examples 1-2 and Comparative Example 1.

[0201] like Figure 10 As shown in the figure, in Examples 1 and 2 where the temperature of the adsorbent was adjusted to the target temperature (90°C or 60°C), the CO2 recovery rate was higher than that in Comparative Example 1 where this operation was not performed, and CO2 was efficiently separated from the feed gas.

[0202] Explanation of reference numerals in the attached figures

[0203] 1: Gas composition 1

[0204] 2: Gas composition 2

[0205] 11, 11a, 11b: Gas separation equipment

[0206] 12, 12a, 12b: Adsorption towers

[0207] 13: Inlet Pipeline (Inlet Section)

[0208] 14: Exhaust gas pipeline

[0209] 15: Desorbed gas exhaust line (pressure reduction section)

[0210] 16: Branch pipeline (pressure relief section)

[0211] 17: Branch pipeline (pressure relief section)

[0212] 18: Vacuum pump (pressure reduction unit)

[0213] 21, 22, 23, 24, 25: On / off valves

[0214] 26, 26a, 26b: Temperature measuring section

[0215] 27: Sheath

[0216] 30: Adsorbent

[0217] 31: Temperature Control Unit

[0218] 35: Control Department

[0219] 41: Temperature Control Unit

[0220] 42: Heat exchanger

[0221] 43: Heat medium source

[0222] 44: Pump

[0223] 45, 45a, 45b: Heat medium pipelines

[0224] 46: On / off valve

[0225] 47: Flow regulating valve

[0226] 48: Bypass

[0227] 49: On / off valve

[0228] 51: Gas Circulation Section

[0229] 52: Circulation pipeline

[0230] 53: Pump

[0231] 61: Raw material gas supply source

Claims

1. A gas separation device, which is a gas separation device that uses pressure swing adsorption to separate and recover gas component 1 from a raw gas containing at least gas component 1 and gas component 2, the gas separation device comprising: An adsorption tower filled with an adsorbent for adsorbing and desorbing gas component 1 and gas component 2; An inlet section introduces the raw material gas into the adsorption tower so that it is adsorbed onto the adsorbent; A pressure reduction section depressurizes the adsorption tower to desorb the raw material gas adsorbed on the adsorbent; A temperature measuring unit, which measures the temperature of the adsorbent; A temperature control unit that regulates the temperature of the adsorbent; and The control unit controls the temperature regulation unit in a manner that ensures the temperature of the adsorbent reaches the target temperature. The target temperature is determined by comparing the temperature change rates of the effective adsorption amounts of the adsorbent by gas component 1 and gas component 2. The control unit determines the target temperature according to the following steps 1 to 3. Step 1: For gas component 1 and gas component 2, based on the adsorption isotherm of gas component i (i = 1, 2) at temperature T, calculate the change in equilibrium adsorption amount corresponding to the pressure swing amplitude, i.e., the effective adsorption amount ΔQ. i (T); Step 2: Calculate the reference temperature T for gas component 1 and gas component 2. A With reference temperature T A The changing temperature T B Effective adsorption capacity ΔQ i (T) rate of temperature change X i (T) A T B ) = 1 - {ΔQ i (T) B ) / ΔQ i (T) A )}, where T A <T B ; Step 3: For gas component 1 and gas component 2, calculate the temperature change rate X of the effective adsorption amount. i (T) A T B Compare the temperature changes T that satisfy the following equation (1). B The target temperature is defined as α, where 0 < α ≤ 1. X1 (T) A T B )<α×X2(T A T B (1) 2. The gas separation device as described in claim 1, wherein, The target temperature is the temperature at which the temperature change rate of the effective adsorption amount of gas component 1 on the adsorbent is less than the temperature change rate of the effective adsorption amount of gas component 2 on the adsorbent.

3. The gas separation device as described in claim 1 or 2, wherein, The pressure reducing unit includes an exhaust pipe for discharging the raw material gas desorbed from the adsorbent. The exhaust pipeline branches are a branch pipeline for exhausting gas component 1 and a branch pipeline for exhausting gas component 2.

4. The gas separation device as described in claim 1 or 2, wherein, The temperature control unit indirectly controls the temperature of the adsorbent by adjusting the temperature of the raw material gas.

5. The gas separation device as described in claim 4, wherein, The temperature control unit includes a heat exchanger capable of variably controlling at least one of the flow rate of the heat medium and the heat transfer area. The temperature of the adsorbent is indirectly adjusted by using the heat exchanger to regulate the temperature of the raw material gas.

6. The gas separation apparatus of claim 5, further comprising a gas circulation section that circulates a portion of the feed gas at the outlet of the heat exchanger to the inlet of the heat exchanger.

7. A gas separation method, which is a gas separation method for separating and recovering gas component 1 from a feed gas containing at least gas component 1 and gas component 2 using pressure swing adsorption, wherein, The raw material gas is introduced into an adsorption tower filled with an adsorbent for adsorbing and desorbing gas component 1 and gas component 2, and is adsorbed onto the adsorbent. The pressure in the adsorption tower is reduced, thereby desorbing the raw material gas adsorbed on the adsorbent. The temperature of the adsorbent is measured using a temperature measuring unit that measures the temperature of the adsorbent. A temperature regulating unit controls the temperature of the adsorbent to adjust it in a way that the temperature of the adsorbent reaches a target temperature. The target temperature is determined by comparing the temperature change rate of the effective adsorption amount of the adsorbent by gas component 1 and gas component 2. Determine the target temperature according to steps 1 to 3 below. Step 1: For gas component 1 and gas component 2, based on the adsorption isotherm of gas component i (i = 1, 2) at temperature T, calculate the change in equilibrium adsorption amount corresponding to the pressure swing amplitude, i.e., the effective adsorption amount ΔQ. i (T); Step 2: Calculate the reference temperature T for gas component 1 and gas component 2. A With reference temperature T A The changing temperature T B Effective adsorption capacity ΔQ i (T) rate of temperature change X i (T) A T B ) = 1 - {ΔQ i (T) B ) / ΔQ i (T) A )}, where T A <T B ; Step 3: For gas component 1 and gas component 2, calculate the temperature change rate X of the effective adsorption amount. i (T) A T B Compare the temperature changes T that satisfy the following equation (1). B The target temperature is defined as α, where 0 < α ≤ 1. X1 (T) A T B )<α×X2(T A T B )…(1)。 8. The gas separation method as described in claim 7, wherein, The target temperature is the temperature at which the temperature change rate of the effective adsorption amount of gas component 1 on the adsorbent is less than the temperature change rate of the effective adsorption amount of gas component 2 on the adsorbent.

9. The gas separation method as described in claim 7 or 8, wherein, The gas components 1 and 2 are adsorbed onto the adsorbent. The gas components 1 and 2 adsorbed on the adsorbent are desorbed separately according to the defined time intervals.

10. The gas separation method as described in claim 7 or 8, wherein, One cycle consists of the process of adsorbing the raw material gas onto the adsorbent and then desorbing it. After at least 5 cycles, the temperature of the adsorbent is measured using the temperature measuring unit, and the temperature regulating unit is controlled to adjust the temperature of the adsorbent to a target temperature.

11. The gas separation method as described in claim 7 or 8, wherein, The temperature of the adsorbent is determined by the maximum value of the temperature amplitude measured by the temperature measuring unit.

12. The gas separation method as described in claim 7 or 8, wherein, The temperature control unit indirectly controls the temperature of the adsorbent by adjusting the temperature of the raw material gas.

13. The gas separation method as described in claim 12, wherein, The temperature control unit includes a heat exchanger capable of variably controlling at least one of the flow rate of the heat medium and the heat transfer area. The temperature of the adsorbent is indirectly adjusted by using the heat exchanger to regulate the temperature of the raw material gas.

14. The gas separation method as described in claim 13, wherein, A portion of the feed gas from the outlet side of the heat exchanger is circulated back to the inlet side of the heat exchanger.

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