Gas-liquid contact apparatus and gas-liquid contact method

Abstract

To provide a gas-liquid contact device that can improve gas-liquid contact efficiency. [Solution] The gas-liquid contact device 100 includes a gas-liquid contact tower 1 that brings a gas G to be contacted and a liquid L into contact. The gas-liquid contact tower 1 includes a liquid supply unit 15 that supplies liquid L from the upper part of the gas-liquid contact tower 1, a gas supply unit 17 that supplies gas G to be contacted from the lower part of the gas-liquid contact tower 1, a perforated plate 10 that divides the inside of the gas-liquid contact tower 1 into a plurality of vertical compartments S, and a post-reaction liquid circulation unit 14 that circulates liquid L within the gas-liquid contact tower 1. The perforated plate 10 has a plurality of through holes 10h that allow liquid L to pass downward and gas G to pass upward. The post-reaction liquid circulation unit 14 supplies liquid L stored below the perforated plate 10 to the area above the perforated plate 10. The amount of liquid L circulated by the post-reaction liquid circulation unit 14 is controlled so that the differential pressure ΔP between the lower space and the upper space with the perforated plate 10 in between becomes a predetermined value.

Description

Technical Field

[0001] The present invention relates to a gas-liquid contact device and a gas-liquid contact method.

Background Art

[0002] Conventionally, a gas-liquid contact device has been proposed for separating and recovering a specific component gas from a contacted gas such as exhaust gas containing specific gas components (hereinafter referred to as specific component gas) such as carbon dioxide and sulfur dioxide by utilizing gas-liquid contact. Separation and recovery of the specific component gas are generally performed by a chemical absorption method. For example, the gas-liquid contact device described in Patent Document 1 causes a contact liquid containing an amine-based compound or the like and the contacted gas to undergo gas-liquid contact in an absorption tower, thereby causing carbon dioxide as a specific component gas in the contacted gas to be contained in the contact liquid for separation and recovery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The gas-liquid contact device described in Patent Document 1 includes an absorption tower that causes a contacted gas containing a specific component gas and a contact liquid to undergo gas-liquid contact, and a regeneration tower that regenerates the contact liquid by heating the contact liquid to dissipate the specific component gas. In the absorption tower, a plurality of compartments are formed, and the contact liquid is withdrawn from each compartment and circulated in the absorption tower for reuse. As a result, the concentration of the specific component gas in the contact liquid increases, and the recovery amount of the specific component gas per unit amount in the contact liquid increases. Therefore, the gas-liquid contact device improves the absorption efficiency of the specific component gas in the contacted gas and suppresses the energy required for regeneration of the contact liquid.

[0005] In such an absorption tower, an absorbent liquid is stored in each compartment and remains at a predetermined liquid level. The liquid level of the absorbent liquid is related to the gas-liquid contact efficiency and is affected by various factors (for example, the empty velocity of the gas being contacted). Generally, the amount of gas being contacted entering the absorption tower and the content of specific component gases in the gas being contacted are not constant but change moment by moment. For example, if the concentration of a specific component gas in the gas being contacted changes, the amount of the specific component gas absorbed by the absorbent liquid changes, which in turn changes the flow rate of the gas being contacted. This, in turn, changes the empty velocity of the gas being contacted, which in turn changes the liquid level of the absorbent liquid. From the viewpoint of improving absorption efficiency, it is preferable that the circulation rate of the absorbent liquid be appropriately adjusted in response to such changes so that the liquid level of the absorbent liquid is maintained at the required height.

[0006] However, the gas-liquid contact apparatus described in Patent Document 1 is not configured to adjust the circulation rate of the absorbent liquid within the absorption tower in this manner. Therefore, the circulation rate of the absorbent liquid may be excessive or insufficient. In that case, the gas-liquid contact efficiency may decrease, the required absorption efficiency may not be obtained, and the energy required for the regeneration of the absorbent liquid may increase.

[0007] This invention has been made in view of the above problems, and aims to improve the gas-liquid contact efficiency in a gas-liquid contact device. [Means for solving the problem]

[0008] According to the present invention, the gas-liquid contact apparatus is a gas-liquid contact apparatus comprising a gas-liquid contact tower for bringing a gas to be contacted and a liquid into contact, The gas-liquid contact tower is A liquid supply unit that supplies liquid from the top of the gas-liquid contact tower, A gas supply unit that supplies the gas to be contacted from the lower part of the gas-liquid contact tower, A perforated plate divides the inside of the gas-liquid contact tower into multiple compartments in the vertical direction, A liquid circulation section that circulates the liquid within the gas-liquid contact tower, A control unit that controls the amount of liquid circulated by the liquid circulation unit, and Equipped with, The perforated plate has multiple through holes that allow liquid from the liquid supply section to pass downwards and gas to be contacted from the gas supply section to pass upwards. The liquid circulation section supplies the liquid stored below the perforated plate to the area above the perforated plate. The control unit adjusts the amount of liquid circulated by the liquid circulation unit so that the differential pressure between the lower space and the upper space, separated by the perforated plate, reaches a predetermined value.

[0009] The applicants have shown that the liquid level (e.g., absorbent) stored in each compartment of the absorption tower is correlated with the differential pressure between the lower and upper spaces of the perforated plate. In other words, the differential pressure can be used as a surname for the liquid level. According to the first invention, the amount of liquid circulated by the liquid circulation unit is adjusted so that the differential pressure becomes a predetermined value, using the differential pressure as an indicator. Therefore, by setting the relationship between the liquid level and the differential pressure obtained in advance so that an appropriate liquid level is obtained from the viewpoint of gas-liquid contact efficiency, etc., when the differential pressure reaches a predetermined value, the liquid level stored in the gas-liquid contact tower can be maintained at an appropriate level.

[0010] The liquid in the gas-liquid contact tower of the gas-liquid contact apparatus according to this second invention is an absorbent liquid that absorbs specific component gases in the gas to be contacted. A gas-liquid contact tower brings a gas to be contacted with an absorbent liquid to absorb specific component gases into the absorbent liquid.

[0011] According to this, the gas-liquid contact tower of a gas-liquid contact apparatus, as an absorption tower that absorbs specific component gases in the gas to be contacted into an absorption liquid, can maintain an appropriate liquid level within the gas-liquid contact tower by setting an appropriate liquid level, for example, from the viewpoint of the absorption efficiency of the specific component gas in the absorption liquid.

[0012] The liquid in the gas-liquid contact tower of the gas-liquid contact apparatus according to this third invention is a post-reaction liquid that has absorbed a specific component gas. In the gas supply section, high-temperature steam and high-temperature specific component gases, which are the gases to be contacted, are discharged from the post-reaction liquid stored at the bottom of the gas-liquid contact tower. A gas-liquid contact tower is used to discharge specific component gases from the reaction liquid.

[0013] According to this, the gas-liquid contact tower of a gas-liquid contact apparatus acts as a regeneration tower that discharges (releases) specific component gases from the reaction liquid that has absorbed them. For example, an appropriate liquid level can be set from the viewpoint of the efficiency of the release of specific component gases from the absorbent liquid that has absorbed the specific component gases, thereby maintaining the liquid level stored in the gas-liquid contact tower at an appropriate level.

[0014] The gas-liquid contact apparatus according to the fourth invention further comprises a regeneration tower that discharges the specific component gas from the post-reaction liquid, which has absorbed the specific component gas from the gas to be contacted in the gas-liquid contact tower, and regenerates the post-reaction liquid as an absorbent liquid.

[0015] According to this, the gas-liquid contact tower of a gas-liquid contact apparatus can increase the concentration of specific component gases in the post-reaction liquid by maintaining an appropriate liquid level within the contact tower. Therefore, the efficiency of the release of specific component gases from the post-reaction liquid in the regeneration tower can be improved. As a result, the gas-liquid contact apparatus can reduce the energy required for the regeneration of the post-reaction liquid.

[0016] The gas-liquid contact tower of the gas-liquid contact apparatus according to the fifth invention is It is equipped with multiple perforated plates arranged in multiple layers, The liquid circulation section supplies liquid above the uppermost perforated plate. The control unit adjusts the circulation rate so that the differential pressure between the lower space of the bottom perforated plate and the upper space of the top perforated plate reaches a predetermined value.

[0017] According to this, the control unit of the gas-liquid contact device adjusts the circulation rate using the differential pressure corresponding to the sum of the liquid levels in all sections of the gas-liquid contact tower as an indicator. Therefore, the sum of the liquid levels in all sections of the gas-liquid contact tower is maintained at an appropriate level.

[0018] The gas-liquid contact tower of the gas-liquid contact apparatus according to the sixth invention is It is equipped with multiple perforated plates arranged in multiple layers, The upper perforated plate has a smaller total opening area due to through holes than the lower perforated plate.

[0019] Generally, in a gas-liquid contact tower, under the same conditions, the liquid level tends to decrease in the upper section. According to the sixth invention, in the gas-liquid contact tower of the gas-liquid contact device, the total opening area of the upper perforated plate is smaller. Also, since the cross-sectional area of the flow path of the contacted gas from below becomes smaller in the upper perforated plate, the pressure loss of the contacted gas becomes larger in the upper section, and the pressure for pushing up the contacted gas through the perforated plate becomes larger. As a result, the amount of dripping of the absorption liquid from the upper perforated plate is suppressed, and the liquid level can be kept high even in the upper section.

[0020] In the gas-liquid contact device according to the seventh invention, the predetermined value is set as the differential pressure when the gas-liquid contact efficiency becomes not less than the required gas-liquid contact efficiency, based on the relationship between the differential pressure obtained in advance and the gas-liquid contact efficiency.

[0021] According to this, the gas-liquid contact device can keep the liquid level in the gas-liquid contact tower at an appropriate level so that, as the gas-liquid contact efficiency, for example, the absorption efficiency of a specific component gas in the absorption liquid, the dissipation efficiency of the specific component gas from the absorption liquid that has absorbed the specific component gas, etc. become not less than the required values.

[0022] The gas-liquid contact method according to the eighth invention is a gas-liquid contact method that partitions the inside of a gas-liquid contact tower into a plurality of sections in the vertical direction and uses a gas-liquid contact device provided with a perforated plate having a plurality of through-holes, in which the contacted gas and the liquid are brought into contact in the gas-liquid contact tower, the through-holes allow the liquid supplied from the upper part of the absorption tower to pass downward and the contacted gas supplied from the lower part of the absorption tower to pass upward, the liquid stored below the perforated plate is supplied above the perforated plate, and the liquid is circulated in the gas-liquid contact tower, and the circulation amount of the liquid is adjusted so that the differential pressure between the lower space and the upper space sandwiching the perforated plate becomes a predetermined value. It is characterized by the above.

[0023] According to this, the gas-liquid contact method can achieve the same operational effects as the first invention. [Effects of the Invention]

[0024] According to the present invention, the gas-liquid contact efficiency can be improved by maintaining the liquid level in the gas-liquid contact tower at an appropriate level. [Brief explanation of the drawing]

[0025] [Figure 1] This figure shows a gas-liquid contact device according to Embodiment 1 of the present invention. [Figure 2] This figure shows the configuration of the gas-liquid contact tower in the gas-liquid contact apparatus. [Figure 3] This is an enlarged cross-sectional view of a portion of a gas-liquid contact tower, illustrating the factors related to the liquid level. [Figure 4] This figure shows the relationship between liquid level and differential pressure obtained in a gas-liquid contact tower. [Figure 5] This figure shows the relationship between the liquid level and the absorption efficiency of a specific component gas in the gas being contacted, obtained in a gas-liquid contact tower. [Figure 6] This flowchart shows the control process for the gas-liquid contact device. [Figure 7] This figure shows the configuration of the gas-liquid contact tower in a gas-liquid contact device according to Embodiment 2 of the present invention. [Figure 8] This figure shows the relationship between the liquid level and the emission efficiency of specific component gases from the reaction liquid, obtained in an isogas-liquid contact tower. [Figure 9] This flowchart shows the control process for the gas-liquid contact device. [Modes for carrying out the invention]

[0026] <Embodiment 1> [Configuration of the gas-liquid contact device 100] Referring to Figure 1, the gas-liquid contact device 100 according to Embodiment 1 will be described.

[0027] As shown in Figure 1, the gas-liquid contact device 100 comprises an absorption tower 1 (an example of a gas-liquid contact tower) and a regeneration tower 2. The absorption tower 1 has a liquid supply unit 15, a gas supply unit 17, and a plurality of perforated plates 10. The liquid supply unit 15 supplies an absorbent liquid L (an example of a liquid) from the upper part of the absorption tower 1 through a plurality of supply nozzles 15n. The gas supply unit 17 supplies the gas to be contacted G from the lower part of the absorption tower 1. The plurality of perforated plates 10 divide the inside of the absorption tower 1 into a plurality of compartments S in the vertical direction and are provided with a plurality of through holes 10h that allow the absorbent liquid L from the liquid supply unit 15 to pass downwards and the gas to be contacted G from the gas supply unit 17 to pass upwards.

[0028] The absorption tower 1 brings the gas to be contacted G from the bottom and the absorbent liquid L from the top into contact within the tower, and absorbs a specific component gas (in this embodiment, for example, carbon dioxide) in the gas to be contacted G into the absorbent liquid L. The absorbent liquid L that has absorbed the specific component gas is stored as a post-reaction liquid L1 in the lower part of the absorption tower 1 and is discharged outside the absorption tower 1 from a post-reaction liquid discharge section 16 provided in the lower part of the absorption tower 1.

[0029] In this embodiment, the absorbent liquid L is, for example, an amine aqueous solution, which absorbs a specific component gas (carbon dioxide). The amine aqueous solution has the property of absorbing carbon dioxide at low temperatures and releasing the absorbed carbon dioxide when heated. When the specific component gas is, for example, sulfur oxides in combustion exhaust gas, the absorbent liquid L may be, for example, magnesium hydroxide, caustic soda, or seawater.

[0030] The absorption tower 1 has a post-reaction liquid circulation section 14 (an example of a liquid circulation section). The post-reaction liquid circulation section 14 consists of a first line 51 and a first pump 61 provided on the first line 51. As will be described in detail later, the post-reaction liquid circulation section 14 is configured to transport a portion of the post-reaction liquid L1 discharged from the post-reaction liquid discharge section 16 to the liquid supply section 15 via the first line 51. In other words, the post-reaction liquid circulation section 14 circulates the post-reaction liquid L1 within the absorption tower 1 for reuse as absorbent liquid L. By adjusting the output of the first pump 61, the amount of post-reaction liquid L1 transported to the liquid supply section 15 is adjusted. In other words, the amount of post-reaction liquid L1 circulating within the absorption tower 1 is adjusted.

[0031] The absorption tower 1 has a pressure difference acquisition unit 45. The pressure difference acquisition unit 45 measures the pressure inside the absorption tower 1 at multiple locations using multiple pressure gauges 40 and acquires the difference between each measured pressure as a pressure difference ΔP (an example of a difference). The contacted gas G, from which specific component gases have been absorbed by the absorption liquid L, is discharged as post-contact gas G1 from the gas discharge unit 18 at the top of the absorption tower 1.

[0032] The regeneration tower 2 includes a post-reaction liquid supply unit 22 and a heater 21. The post-reaction liquid supply unit 22 supplies the post-reaction liquid L1 discharged from the absorption tower 1 into the regeneration tower 2 from the upper part of the regeneration tower 2 via a plurality of supply nozzles 22n. The supplied post-reaction liquid L1 is stored in the lower part of the regeneration tower 2. The heater 21 is located in the lower part of the regeneration tower 2 and heats the stored post-reaction liquid L1. This causes specific component gases to be released from the post-reaction liquid L1.

[0033] High-temperature vapor V and carbon dioxide (not shown), a specific component gas, are released at high temperatures from the heated post-reaction liquid L1 and rise through the regeneration tower 2. The post-reaction liquid L1 from the top of the regeneration tower 2 comes into gas-liquid contact with the high-temperature vapor V and high-temperature specific component gas inside the regeneration tower 2, and carbon dioxide, the specific component gas, is released again as a result. In other words, the regeneration tower 2 regenerates the post-reaction liquid L1, which has absorbed the specific component gas in the absorption tower 1, by releasing the specific component gas, and uses the post-reaction liquid L1 as absorbent liquid L. The released specific component gas and high-temperature vapor V are discharged as regenerated gas G2 from the regenerated gas discharge section 24 at the top of the regeneration tower 2.

[0034] A specific component gas concentration acquisition unit 46 is provided near the outlet of the regenerated gas discharge unit 24. The specific component gas concentration acquisition unit 46 acquires the concentration of specific component gases (in this embodiment, carbon dioxide concentration; the unit is, for example, [ppm]) contained in the regenerated gas G2 discharged from the regenerated gas discharge unit 24. For example, an optical carbon dioxide concentration meter is used for the specific component gas concentration acquisition unit 46.

[0035] In the specific component gas concentration acquisition unit 46, the specific component gas concentration is acquired at predetermined time intervals and evaluated against a predetermined standard value (standard specific component gas concentration). For example, if the gas-liquid contact device 100 is operating at a concentration below this standard specific component gas concentration, it is evaluated that the gas-liquid contact efficiency in the gas-liquid contact device 100 has decreased.

[0036] Of the post-reaction liquid L1 discharged from the post-reaction liquid discharge section 16 in the absorption tower 1, the post-reaction liquid L1 that is not recirculated into the absorption tower 1 by the post-reaction liquid circulation section 14 is transported to the post-reaction liquid supply section 22 via the second line 52, the second pump 62, the heat exchanger 65, and the third line 53 in that order. The amount of post-reaction liquid L1 transported to the post-reaction liquid supply section 22 is adjusted by adjusting the output of the second pump 62.

[0037] The absorbent liquid L regenerated in the regeneration tower 2 is discharged from the liquid discharge section 23 located at the bottom of the regeneration tower 2. The absorbent liquid L discharged from the liquid discharge section 23 is transported to the liquid supply section 15 of the absorption tower 1 via the fourth line 54, the third pump 63, the heat exchanger 65, the fifth line 55, and the temperature control device 66 in that order. The amount of absorbent liquid L transported to the liquid supply section 15 is adjusted by adjusting the output of the third pump 63. In the heat exchanger 65, thermal energy is exchanged between the absorbent liquid L and the post-reaction liquid L1. In the temperature control device 66, the absorbent liquid L is adjusted to a predetermined temperature.

[0038] Although not shown in the diagram, the liquid supply unit 15, gas supply unit 17, and post-reaction liquid supply unit 22 are equipped with valve mechanisms and the like, and are configured to allow adjustment of the supply amounts of the absorbent liquid L, the gas to be contacted G, and the post-reaction liquid L1.

[0039] [Configuration of the gas-liquid contact tower (absorption tower 1)] Referring to Figure 2, the configuration of the absorption tower 1 will be explained. As shown in Figure 2, the absorption tower 1 is provided with multiple perforated plates 10, such as a first perforated plate 11, a second perforated plate 12, and a third perforated plate 13. As a result, the inside of the absorption tower 1 is partitioned by each perforated plate 10, forming a first compartment S1, a second compartment S2, a third compartment S3, a fourth compartment S4 (an example of multiple compartments).

[0040] The absorbent liquid L from the liquid supply unit 15 passes through the first section S1 to the fourth section S4 in that order, and a predetermined amount of absorbent liquid L is stored in each section S. As a result, the height (liquid level H) of the absorbent liquid L from each perforated plate 10 in each section S becomes the first liquid level H1, the second liquid level H2, and the third liquid level H3.

[0041] The gas G to be contacted from the gas supply unit 17 passes through the fourth compartment S4 to the first compartment S1 in this order. During this process, the gas G to be contacted passes through each through-hole 10h of each perforated plate 10 and comes into gas-liquid contact with the absorbent liquid L stored in each compartment S, thereby absorbing specific component gases in the gas G to be contacted into the absorbent liquid L.

[0042] Multiple through-holes 10h are formed in the perforated plate 10. In this embodiment, the through-holes 10h in each perforated plate 10 are of the same size, and the number of through-holes 10h in each perforated plate 10 decreases in the order of the third perforated plate 13, the second perforated plate 12, and the first perforated plate 11. Therefore, the total opening area by each through-hole 10h decreases in the order of the third perforated plate 13, the second perforated plate 12, and the first perforated plate 11, i.e., the upper plates, and the pressure loss increases in the upper plates. However, other methods are also acceptable as long as the pressure loss increases in the upper perforated plates 10. For example, the number of through-holes 10h in each perforated plate 10 may be the same, and the size of the through-holes 10h may decrease in the order of the third perforated plate 13, the second perforated plate 12, and the first perforated plate 11. Furthermore, the number and size of the through holes 10h in each perforated plate 10 may be configured to be the same for each perforated plate 10.

[0043] The absorption tower 1 includes a pressure difference acquisition unit 45, a pump drive unit 48, and a control unit 47. The pressure difference acquisition unit 45 acquires the pressure of the gas phase portion in each compartment S and acquires the difference between them as a pressure difference ΔP. In this embodiment, for example, the pressure of the gas phase portion of the first compartment S1 is acquired as P1 by the pressure gauge 40, the pressure of the gas phase portion of the fourth compartment S4 is acquired as P4 by the pressure gauge 40, and the pressure difference ΔP between these is acquired as the total pressure difference ΔPt = P4 - P1. For example, a diaphragm type pressure gauge is used for the pressure gauge 40.

[0044] The pump drive unit 48 adjusts the output of the first pump 61 to adjust the amount of post-reaction liquid L1 circulated by the post-reaction liquid circulation unit 14. The control unit 47 controls the pump drive unit 48 using the pressure difference ΔP acquired by the pressure difference acquisition unit 45 as a control variable (details will be described later).

[0045] [Relationship between liquid level H and pressure difference ΔP] Referring to Figure 3, the relationship between the liquid level H of the absorbent liquid L in each compartment S and the pressure difference ΔP obtained by the pressure difference acquisition unit 45 will be explained. In Figure 3, as an example, a magnified view of a portion of the upper and lower first compartment S1 and second compartment S2 of the first perforated plate 11 is shown. In Figure 3, for the purpose of explanation, the pressure difference acquisition unit 45 is assumed to have acquired the pressure in the gas phase portion of the first compartment S1 as P1, the pressure in the gas phase portion of the second compartment S2 as P2, and the pressure difference ΔP between these two as the first pressure difference ΔP1 (= P2 - P1).

[0046] As shown in the figure, absorbent liquid L is supplied to the first compartment S1, and a portion of the absorbent liquid L stored in the first compartment S1 drips into the second space through the through-hole 10h. Therefore, the first liquid level H1 is formed when the flow rate of absorbent liquid L supplied to the first compartment S1 is greater than the flow rate of absorbent liquid L (dropping absorbent liquid Ld) dripping into the second compartment S2. In this embodiment, the opening area of ​​each perforated plate 10 is appropriately set, so that the flow rates of absorbent liquid L and dropping absorbent liquid Ld are appropriately adjusted and maintained in a state where each liquid level H is formed.

[0047] When the first liquid level H1 is formed, a hydrostatic pressure is generated on the upper surface of the first porous plate 11. As a result, the pressure P2 in the gas phase portion of the second compartment S2 becomes greater than the pressure P1 in the gas phase portion of the first compartment S1 by the amount of the hydrostatic pressure. In other words, the first pressure difference ΔP1 (=P2-P1) is related to the first liquid level H1. The relationship between the pressure difference ΔP and the liquid level H will be explained with reference to Figure 4. Figure 4 was obtained by changing various conditions related to the liquid level H in the absorption tower 1 according to this embodiment. As shown in the figure, the pressure difference ΔP and the liquid level H have an extremely good correlation (correlation coefficient of the approximation line 81: 0.99). Therefore, by referring to the approximation line 81, the liquid level H corresponding to the first pressure difference ΔP1 can be predicted as the first liquid level H1. In other words, the first pressure difference ΔP1 can be used as a substitute value for the first liquid level H1.

[0048] Similarly, if we let P3 be the pressure in the gas phase portion of the third compartment S3 shown in Figure 2, and let the pressure differences above and below the second and third perforated plates be the second pressure difference ΔP2 (=P3-P2) and the third pressure difference ΔP3 (=P4-P3), respectively, then these can be used as substitute values ​​for the second liquid level H2 and the third liquid level H3.

[0049] As described above, in this embodiment, the pressure difference acquisition unit 45 of the absorption tower 1 acquires the pressure of the gas phase portion of the first compartment S1 as P1, the pressure of the gas phase portion of the fourth compartment S4 as P4, and the pressure difference ΔP between them as the total pressure difference ΔPt = P4 - P1. Here, the total pressure difference ΔPt = first pressure difference ΔP1 (= P2 - P1) + second pressure difference ΔP2 (= P3 - P2) + third pressure difference ΔP3 (= P4 - P3) = P4 - P1. In other words, the total pressure difference ΔPt is equal to the sum of the pressure differences ΔP in the upper and lower spaces of each perforated plate 10. Therefore, the total pressure difference ΔPt can be used as a substitute value for the sum from the first liquid level H1 to the third liquid level H3.

[0050] [Regarding the target pressure difference ΔPd] The target value of the pressure difference ΔP used in the control unit 47 of the absorption tower 1 (target pressure difference ΔPd: an example of a predetermined value) will be explained. First, referring to Figure 5, the relationship between the liquid level H and the absorption efficiency of a specific component gas per unit time in the absorption liquid L (gas absorption efficiency Ar: an example of gas-liquid contact efficiency) will be explained. Figure 5 was obtained by changing various conditions related to the liquid level H in the absorption tower 1 according to this embodiment. From the approximation curve 82, the gas absorption efficiency Ar tends to increase as the liquid level H increases.

[0051] As shown in Figure 3, the gas to be contacted G supplied from the bottom of the absorption tower 1 enters gas-liquid contact with the absorbent liquid L stored in the first compartment S1 via the through-hole 10h from the second compartment S2. The gas to be contacted G then reaches the gas phase portion of the first compartment S1. It is presumed that the higher the liquid level H, the longer the gas-liquid contact time between the gas to be contacted G and the absorbent liquid L, thus resulting in the trend shown in Figure 5.

[0052] However, as shown in the figure, the rate of increase tends to decrease as the liquid level H increases. Also, if the liquid level H becomes too high, there is a problem that the amount of absorbent liquid component that flows out of the system accompanied by the gas G1 after contact increases. Therefore, it is preferable to set the target liquid level Hd at a liquid level H that is predicted to yield a gas absorption efficiency Ar of Ard or higher in the approximate curve 82, and that does not have any trade-offs such as an increase in the absorbent liquid component that flows out of the system. Then, referring to the approximate straight line 81 in Figure 4, it is preferable to set the target pressure difference ΔPd at a pressure difference ΔPd that corresponds to the target liquid level Hd.

[0053] As described above, in this embodiment, the total pressure difference ΔPt acquired by the pressure difference acquisition unit 45 of the absorption tower 1 corresponds to the sum of the liquid levels H in each compartment S. Therefore, the target pressure difference ΔPd is also set as a value corresponding to the sum of the target liquid levels Hd in each compartment S.

[0054] [Relationship between liquid level H and opening area] Referring again to Figure 3, the relationship between the liquid level H of the absorbent liquid L in each compartment S and the opening area in the perforated plate 10 will be explained. As described above, the first liquid level H1 is formed when the flow rate of the absorbent liquid L supplied to the first compartment S1 is greater than the flow rate of the absorbent liquid Ld dropped into the second compartment S2.

[0055] The flow rate of the dripping absorption solution Ld is affected by the flow velocity (empty column velocity) of the gas G in contact with the absorption column 1 from the bottom. When the empty column velocity is high, the flow rate of the dripping absorption solution Ld decreases and the liquid level H increases. When the empty column velocity is low, the flow rate of the dripping absorption solution Ld increases and the liquid level H decreases. Under the same conditions, the liquid level H tends to decrease in the upper section S of the absorption column 1 due to reasons such as the decrease in empty column velocity.

[0056] As described above, in this embodiment, the total opening area of ​​each perforated plate 10 is smaller for the upper perforated plate 10. Also, since the cross-sectional area of ​​the flow path for the gas G that is in contact from below is smaller for the upper perforated plate 10, the pressure loss of the gas G that is in contact becomes larger for the upper compartment S, and the pressure exerted by the gas G that pushes up the perforated plate 10 becomes larger.

[0057] As a result, the flow rate of the dripping absorbent liquid Ld from the upper perforated plate 10 is suppressed, increasing the amount of absorbent liquid L stored in the upper compartment S, and raising its liquid level H. Therefore, the tendency for the liquid level H to decrease in the upper compartment S of the absorption tower 1 is mitigated, and the liquid level H in each compartment S, including the first compartment S1 of the upper section, is kept high.

[0058] [Processing flow of control unit 47] Next, referring to Figure 6, the processing flow in the control unit 47 of the absorption tower 1 will be explained. First, the control unit 47 acquires the specific component gas concentration from the specific component gas concentration acquisition unit 46 at predetermined time intervals (step S21). Then, it is determined whether the acquired specific component gas concentration is less than a predetermined standard specific component gas concentration (step S22). If the specific component gas concentration is equal to or greater than the standard specific component gas concentration (No in step S22), the processing ends (END).

[0059] If the concentration of a specific component gas is less than the standard concentration of a specific component gas (Yes in step S22), the control unit 47 obtains the total pressure difference ΔPt from the pressure difference acquisition unit 45 (step S23). Then, it is determined whether the obtained total pressure difference ΔPt is less than a predetermined target pressure difference ΔPd (step S24). If the total pressure difference ΔPt is greater than or equal to the target pressure difference ΔPd (No in step S24), the process ends (END).

[0060] If the total pressure difference ΔPt is less than the target pressure difference ΔPd (Yes in step S24), the control unit 47 increases the amount of post-reaction liquid L1 transported by the first pump 61 in the pump drive unit 48 (step S25). As a result, the amount of post-reaction liquid L1 circulated in the absorption tower 1 by the post-reaction liquid circulation unit 14 increases and is reused as absorbent liquid L. Therefore, as the liquid level H in each compartment S increases, the total pressure difference ΔPt, which is correlated with the liquid level H, also increases. After a predetermined time has elapsed, the control unit 47 again acquires the total pressure difference ΔPt from the pressure difference acquisition unit 45 (step S23). The processes in steps 25 and S23 are repeated until the acquired total pressure difference ΔPt becomes equal to or greater than the target pressure difference ΔPd (No in step S24).

[0061] After the processing is complete, the total pressure difference ΔPt is greater than or equal to the target pressure difference ΔPd, which suggests that the liquid level H at this time is greater than or equal to the target liquid level Hd. Furthermore, since the liquid level H is equal to the target liquid level Hd, it is predicted that the gas absorption efficiency Ar at this time is greater than or equal to the required gas absorption efficiency Ard.

[0062] In this process, the control unit 47 uses the total pressure difference ΔPt as the control variable, and adjusts the circulation rate in the post-reaction liquid circulation unit 14 based on the sum of the liquid levels H in all compartments S within the absorption tower 1. Therefore, the sum of the liquid levels H in all compartments S within the absorption tower 1 is maintained at an appropriate liquid level H.

[0063] Furthermore, as described above, the opening area of ​​each perforated plate 10 is configured to be smaller for the upper perforated plates 10, which allows the liquid level H to be kept high in each compartment S, including the upper first compartment S1, within the absorption tower 1. As a result, the gas absorption efficiency Ar of the absorption tower 1 is set to the required efficiency, and the concentration of specific component gases in the post-reaction liquid L1 increases. This improves the emission efficiency of specific component gases from the post-reaction liquid L1 in the regeneration tower 2, thereby suppressing the energy required for the regeneration of the post-reaction liquid L1.

[0064] Furthermore, the gas-liquid contact device 100, configured as described above, can continuously monitor the total pressure difference ΔPt over a long period of time. This ensures that the liquid level H remains constant, preventing the generation of entrained gases due to excessively high liquid levels H.

[0065] <Embodiment 2> [Configuration of the gas-liquid contact tower (regeneration tower 3)] Next, with reference to Figure 7, a gas-liquid contact apparatus 200 according to Embodiment 2 of the present invention will be described. The gas-liquid contact apparatus 200 comprises an arbitrary absorption tower (not shown) and a regeneration tower 3 (another example of a gas-liquid contact tower). The arbitrary absorption tower is, for example, an absorption tower that absorbs specific component gases in the exhaust gas as carbon dioxide into an absorption liquid L, and the absorption liquid L that has absorbed the specific component gases is sent outside the absorption tower as a post-reaction liquid L1. The arbitrary absorption tower may be the absorption tower 1 of Embodiment 1 described above.

[0066] The regeneration tower 3 has, in addition to the regeneration tower 2 according to Embodiment 1 described above, a plurality of perforated plates 10 and a liquid circulation section 31. The plurality of perforated plates 10 include, for example, a first perforated plate 11 and a second perforated plate 12, thereby dividing the inside of the regeneration tower 3 into sections by each perforated plate 10, forming a first section S1, a second section S2, a third section S3 (another example of multiple sections).

[0067] The liquid circulation unit 31 consists of a sixth line 56 and a fourth pump 64 provided on the sixth line 56. The liquid circulation unit 31 is configured to transport a portion of the absorbent liquid L discharged from the liquid discharge unit 23 as post-reaction liquid L1 to the post-reaction liquid supply unit 22 via the sixth line 56. In other words, the liquid circulation unit 31 circulates the post-reaction liquid L1 within the regeneration tower 3 and performs superimposed regeneration processing. By adjusting the output of the fourth pump 64, the amount of post-reaction liquid L1 transported to the post-reaction liquid supply unit 22 is adjusted. In other words, the amount of post-reaction liquid L1 circulating within the regeneration tower 3 is adjusted.

[0068] The configuration of each perforated plate 10 is the same as that of the perforated plate 10 in Embodiment 1, and the other configurations in the regeneration tower 3 are the same as those in the gas-liquid contact device 100 in Embodiment 1. Therefore, the same reference numerals as in Embodiment 1 are used, and a detailed explanation is omitted.

[0069] The post-reaction liquid L1 from the post-reaction liquid supply unit 22 passes through the first compartment S1 to the third compartment S3 in that order, and a predetermined amount of post-reaction liquid L1 is stored in each compartment S. As a result, the height (liquid level H) of the post-reaction liquid L1 from each perforated plate 10 in each compartment S becomes the first liquid level H11 and the second liquid level H12.

[0070] A mixture of high-temperature specific component gases, carbon dioxide (not shown in the illustration) and high-temperature steam V (an example of a gas to be contacted), generated (released) from the post-reaction liquid L1 stored in the lower part of the regeneration tower 2, passes through the third compartment S3 to the first compartment S1 in that order. In this process, the high-temperature steam V and high-temperature specific component gases come into gas-liquid contact with the post-reaction liquid L1 stored in each compartment S, heating the post-reaction liquid L1 and releasing carbon dioxide, the specific component gas, from the post-reaction liquid L1.

[0071] In this embodiment, the pressure difference acquisition unit 45 acquires, for example, the pressure in the gas phase portion of the first section S1 as P1 by the pressure gauge 40, the pressure in the gas phase portion of the third section S3 as P3 by the pressure gauge 40, and the pressure difference ΔP between these is acquired as the total pressure difference ΔPt = P3 - P1. Similar to the first embodiment, the total pressure difference ΔPt can be used as a substitute value for the sum of the liquid levels H in each section S by referring to the approximate straight line 81 in Figure 4.

[0072] [Regarding the target pressure difference ΔPd] The target value of the total pressure difference ΔPt used in the control unit 47 of the regeneration tower 3 (target pressure difference ΔPd: an example of a predetermined value) will be explained. Referring to Figure 8, the relationship between the liquid level H and the emission rate of specific component gases per unit time from the post-reaction liquid L1 (gas emission efficiency Er: another example of gas-liquid contact efficiency) will be explained. Figure 8 was obtained by changing various conditions related to the liquid level H in the regeneration tower 3 according to this embodiment. From the approximation curve 83, it can be seen that the gas emission efficiency Er tends to increase as the liquid level H increases. Similar to the first embodiment, it is presumed that the gas-liquid contact time between the high-temperature vapor V and the high-temperature specific component gas and the post-reaction liquid L1 becomes longer as the liquid level H increases, thus obtaining the trend shown in Figure 8.

[0073] Similar to Embodiment 1, it is preferable to set the target liquid level Hd at a liquid level H that is predicted to yield a gas emission efficiency Er equal to or greater than the required gas emission efficiency Er in the approximation curve 83, and that does not have any particular conflicts. Then, referring to Figure 4, it is preferable to set the target pressure difference ΔPd at the approximation line 81 at a pressure difference ΔP corresponding to the target liquid level Hd. The target pressure difference ΔPd is set as a value corresponding to the sum of the target liquid levels Hd in each section S.

[0074] [Processing flow of control unit 47] Figure 9 shows the processing flow in the control unit 47 of the regeneration tower 3. The processing flow in the regeneration tower 3 (steps S31 to S35 in Figure 9) is the same as the description of Embodiment 1 above, with the "first pump 61" replaced by the "fourth pump 64" and the "reaction liquid L1" replaced by the "absorbent liquid L," referring to steps S21 to S25 in Figure 6. Therefore, by making these substitutions and referring to the above description, a detailed explanation can be omitted.

[0075] After the processing is complete, the pressure difference ΔP is expected to be greater than or equal to the target pressure difference ΔPd, and therefore the liquid level H is expected to be greater than or equal to the target liquid level Hd. Furthermore, since the liquid level H is at the target liquid level Hd, it is expected that the gas release efficiency Er is greater than or equal to the required gas release efficiency Erd.

[0076] Similar to Embodiment 1, the control unit 47 controls the total pressure difference ΔPt, thereby maintaining the sum of the liquid levels H in all compartments S within the absorption tower 1 at an appropriate level H. Furthermore, the opening area of ​​each perforated plate 10 is configured to be smaller for the upper perforated plates 10, allowing the liquid level H to be maintained at a high level in each compartment S. As a result, the regeneration tower 2 can improve its gas emission efficiency Er. This suppresses the energy required for the regeneration of the post-reaction liquid L1.

[0077] In the gas-liquid contact towers (absorption tower 1, regeneration tower 3) of each embodiment described above, two or three perforated plates 10 are provided. However, the number of perforated plates 10 is not limited to these, and one plate may be provided, or any number of plates may be provided.

[0078] Furthermore, in the gas-liquid contact tower described above, the differential pressure between the lower space of the lowest perforated plate 10 and the upper space of the uppermost perforated plate 10 is acquired by the pressure difference acquisition unit 45 as the total pressure difference ΔPt, and this is used as the control amount by the control unit 47.

[0079] However, the gas-liquid contact tower may be configured such that multiple pressure gauges 40, shown by solid and dashed lines in Figures 2 and 7, are placed in any compartment S, and the differential pressure between the upper and lower spaces of any perforated plate 10 is acquired as one or more pressure differences ΔP by the pressure difference acquisition unit 45, and one or more pressure differences ΔP are used as control variables by the control unit 47. Alternatively, the gas-liquid contact tower may be configured such that all of the pressure gauges 40, shown by solid and dashed lines in Figures 2 and 7, are placed in each compartment S, and the differential pressure in the upper and lower spaces of all perforated plates 10 is acquired as a pressure difference ΔP by the pressure difference acquisition unit 45, and each of the pressure differences ΔP is used as a control variable by the control unit 47.

[0080] Furthermore, in the gas-liquid contact tower described above, the liquid (post-reaction liquid L1, absorbent liquid L) from below the lowest perforated plate 10 (bottom of the gas-liquid contact tower) was transported by the liquid circulation section (post-reaction liquid circulation section 14, liquid circulation section 31) to above the uppermost perforated plate 10 (liquid supply section 15, post-reaction liquid supply section 22) and circulated within the gas-liquid contact tower.

[0081] However, the gas-liquid contact tower may be configured to have one or more liquid circulation units that supply the liquid stored below any perforated plate 10 to the area above that perforated plate 10. Alternatively, the gas-liquid contact tower may be configured to have liquid circulation units that supply the liquid stored below each of the perforated plates 10 to the area above each of the perforated plates 10.

[0082] In a gas-liquid contact tower, if multiple liquid circulation sections are provided in multiple compartments S as described above and their circulation rates are controlled, a target liquid level Hd (or target pressure difference ΔPd) may be set for each liquid circulation section and the circulation rate of each section may be controlled individually. [Explanation of symbols]

[0083] L Absorbent Solution L1 Reaction solution G Contacted gas G1 Contact gas H liquid level Section S V High-temperature steam ΔP pressure difference ΔPt Total pressure difference 1. Absorption tower (an example of a gas-liquid contact tower) 2 Regeneration Tower 10 perforated plate 10h through hole 14 Post-reaction liquid circulation section 15 Liquid supply section 16. Post-reaction liquid discharge section 17 Gas Supply Department 18 Gas discharge section 45 Pressure difference acquisition unit 46. ​​Unit for obtaining specific component gas concentration 47 Control Unit 48 Pump drive unit 51 First Line 52 Second Line 61 Pump No. 1 62 Pump No. 2 100 Gas-liquid contact device

Claims

1. A gas-liquid contact apparatus comprising a gas-liquid contact tower for bringing a gas to be contacted and a liquid into contact, The gas-liquid contact tower is A liquid supply unit that supplies liquid from the top of the gas-liquid contact tower, A gas supply unit that supplies the gas to be contacted from the lower part of the gas-liquid contact tower, A perforated plate divides the inside of the gas-liquid contact tower into multiple compartments in the vertical direction, A liquid circulation section that circulates the liquid within the gas-liquid contact tower, A control unit that controls the amount of liquid circulated by the liquid circulation unit, and Equipped with, The perforated plate has multiple through holes that allow liquid from the liquid supply section to pass downwards and gas to be contacted from the gas supply section to pass upwards. The liquid circulation section supplies the liquid stored below the perforated plate to the area above the perforated plate. The control unit adjusts the amount of liquid circulated by the liquid circulation unit so that the differential pressure between the lower space and the upper space, which are separated by the perforated plate, reaches a predetermined value. A gas-liquid contact apparatus characterized by the following features.

2. The liquid is an absorbent that absorbs specific component gases in the gas being contacted. The gas-liquid contact tower is a gas-liquid contact apparatus according to claim 1, wherein a gas to be contacted and an absorbent liquid are brought into contact to absorb a specific component gas into the absorbent liquid.

3. The liquid is the post-reaction liquid that has absorbed specific component gases. In the gas supply section, high-temperature steam and high-temperature specific component gases, which are the gases to be contacted, are discharged from the post-reaction liquid stored at the bottom of the gas-liquid contact tower. The gas-liquid contact tower discharges a specific component gas from the reaction liquid, as described in claim 1.

4. The gas-liquid contact apparatus according to claim 2, further comprising a regeneration tower that discharges the specific component gas from the post-reaction liquid, which has absorbed the specific component gas in the gas to be contacted in the gas-liquid contact tower, and regenerates the post-reaction liquid as an absorbent liquid.

5. The gas-liquid contact tower is It is equipped with multiple perforated plates arranged in multiple layers, The liquid circulation section supplies liquid above the uppermost perforated plate. The gas-liquid contact device according to any one of claims 1 to 4, wherein the control unit adjusts the circulation amount so that the differential pressure between the lower space of the lowest perforated plate and the upper space of the uppermost perforated plate becomes a predetermined value.

6. The gas-liquid contact tower is It is equipped with multiple perforated plates arranged in multiple layers, The gas-liquid contact apparatus according to any one of claims 1 to 4, wherein the upper perforated plate has a smaller total opening area due to through holes than the lower perforated plate.

7. A gas-liquid contact device according to any one of claims 1 to 4, wherein the predetermined value is set as the differential pressure at which the gas-liquid contact efficiency is equal to or greater than the required gas-liquid contact efficiency, based on the relationship between the differential pressure and the gas-liquid contact efficiency which is determined in advance.

8. A gas-liquid contact method using a gas-liquid contact device that divides the inside of a gas-liquid contact tower into multiple compartments in the vertical direction and is equipped with a perforated plate having multiple through holes, In a gas-liquid contact tower, the gas to be contacted and the liquid are brought into contact. The through-hole allows the liquid supplied from the top of the absorption tower to pass downwards, and the gas to be contacted supplied from the bottom of the absorption tower to pass upwards. The liquid stored below the perforated plate is supplied above the perforated plate, and the liquid circulates within the gas-liquid contact tower. The amount of liquid circulating is adjusted so that the pressure difference between the lower space and the upper space, separated by the perforated plate, reaches a predetermined value. A gas-liquid contact method characterized by the following:

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