Gas treatment system

Abstract

The present invention addresses the problem of providing a gas treatment system that reduces energy consumption. This gas treatment system is provided with: an electric dust collector for collecting impurities in combustion exhaust gas containing CO2; a first flow path through which the ozone-containing combustion exhaust gas that has passed through the electric dust collector flows; a storage tank for temporarily storing the combustion exhaust gas flowing through the first flow path; a second flow path through which the combustion gas that has passed through the storage tank flows; a third flow path that branches from the second flow path and causes at least a portion of the combustion exhaust gas flowing through the second flow path to flow back to the first flow path; a first regulating valve for regulating the opening degree of the third flow path; a first detection unit that detects a first flow rate related to the combustion exhaust gas supplied to the electric dust collector; and a control unit that controls the degree of opening of the first regulating valve on the basis of the first flow rate detected by the first detection unit.

Description

Technical Field

[0001] The present invention relates to a gas treatment system. Background Art

[0002] Conventionally, an ozone decomposition device for thermally decomposing ozone has been known. For example, Patent Document 1 discloses an ozone decomposition treatment device having a heat exchanger provided with a passage through which ozone gas after heat treatment using a heater passes, thereby extending the residence time of the ozone gas before heat treatment.

[0003] In addition, Patent Document 2 discloses a CO2 separation system including an electrostatic precipitator for collecting impurities in combustion exhaust gas containing CO2. In the CO2 separation system disclosed in Patent Document 2, there is a possibility of generating ozone from oxygen molecules in the combustion exhaust gas due to corona discharge accompanying the operation of the electrostatic precipitator.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-774

[0007] Patent Document 2: WO 2014 / 136599 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The CO2 separation system needs to reduce energy consumption. The same applies when decomposing ozone generated by the CO2 separation system equipped with an electrostatic precipitator using the ozone decomposition treatment device disclosed in Patent Document 1. However, the ozone decomposition treatment device disclosed in Patent Document 1 only heats ozone with a heater, and thus there is room for improvement from the viewpoint of reducing energy consumption.

[0010] The present invention provides a gas treatment system that reduces energy consumption.

[0011] Means for Solving the Problems

[0012] In the first mode, it includes: an electrostatic precipitator for collecting impurities in the combustion exhaust gas containing CO2; a first flow path through which the combustion exhaust gas containing ozone flows after passing through the electrostatic precipitator; a storage tank for temporarily storing the combustion exhaust gas flowing through the first flow path; a second flow path through which the combustion exhaust gas flowing through the storage tank flows; a third flow path branched from the second flow path to return at least a part of the combustion exhaust gas flowing through the second flow path to the first flow path; a first regulating valve for adjusting the opening degree of the third flow path; a first detection unit for detecting a first flow rate related to the combustion exhaust gas supplied to the electrostatic precipitator; and a control unit for controlling the opening degree of the first regulating valve based on the first flow rate detected by the first detection unit.

[0013] Advantages of the Invention

[0014] According to the technology of the present invention, energy consumption can be reduced. Description of the Drawings

[0015] Figure 1 It is a schematic diagram showing an example of the overall configuration of the gas treatment system according to the first embodiment.

[0016] Figure 2 It is a graph for explaining the outline of the temporal change of ozone concentration under multiple different temperature conditions.

[0017] Figure 3 It is a schematic side view showing an example of the configuration of the storage tank of the gas treatment system according to the first embodiment.

[0018] Figure 4 It is a block diagram showing an example of the configuration of the control unit of the gas treatment system according to the first embodiment.

[0019] Figure 5 It is a flowchart for explaining the opening degree control operation of the first regulating valve in the control unit of the first embodiment.

[0020] Figure 6 It is a schematic diagram showing an example of the overall configuration of the gas treatment system according to the second embodiment.

[0021] Figure 7 It is a flowchart for explaining the control operation of the heater temperature in the control unit of the second embodiment.

[0022] Figure 8 It is a schematic diagram showing an example of the overall configuration of the gas treatment system according to the third embodiment.

[0023] Explanation of Reference Numerals

[0024] 1, 1A, 1B Gas treatment system

[0025] 10 Electrostatic precipitator

[0026] 21 First flow path

[0027] 22 Second flow path

[0028] 23 Third flow path

[0029] 24 Fourth flow path

[0030] 30 Storage tank

[0031] 40 First regulating valve

[0032] 45 Second regulating valve

[0033] 51 First detection unit

[0034] 52 Second detection unit

[0035] 53 Third detection unit

[0036] 60 Control unit

[0037] 80 Separation membrane module

[0038] 82 Vacuum pump Detailed implementation mode

[0039] Hereinafter, an example of a gas treatment system according to an embodiment will be described with reference to the drawings. The "connection" described herein is not limited to the case where one component A is directly connected to another component B, but also includes the case where component A is connected to component B via one or more other components.

[0040] First embodiment

[0041] <Overall configuration>

[0042] Refer to Figures 1 to 4 , which shows a configuration example of the gas treatment system 1 according to the first embodiment. Figure 1 is a schematic diagram showing an example of the overall configuration of the gas treatment system 1 according to the first embodiment. Figure 2 is a curve graph for explaining the outline of the time change of ozone concentration under multiple different temperature conditions. Figure 3 is a schematic side view showing a configuration example of the storage tank 30 of the gas treatment system 1 according to the first embodiment. Figure 4 is a block diagram showing a configuration example of the control unit 60 of the gas treatment system 1 according to the first embodiment.

[0043] In the gas treatment system 1, combustion exhaust gas containing CO2 discharged from various devices and / or equipment is supplied. For example, in the gas treatment system 1, combustion exhaust gas discharged from the engine 100E provided in a ship is supplied. As an example, the case where the combustion exhaust gas discharged from the engine 100E is supplied to the gas treatment system 1 will be described. However, the combustion exhaust gas supplied to the gas treatment system 1 is not limited to the exhaust gas discharged from the engine 100E provided in a ship. For example, the combustion exhaust gas supplied to the gas treatment system 1 can be discharged from a combustion device that burns fossil fuels such as a boiler in a coal-fired power plant. In the following description, as the flow direction of the fluid including the combustion exhaust gas, the side closer to the engine 100E is referred to as "upstream". On the other hand, the side farther from the engine 100E is referred to as "downstream". The engine 100E and the above-mentioned combustion device are examples of "combustion exhaust gas emission sources".

[0044] The combustion exhaust gas contains impurities such as soot. Since the impurities from the combustion exhaust gas are adsorbed on the CO2 separation section such as a separation membrane module or a CO2 absorption tower, for example, the CO2 separation operation may be hindered. Therefore, in the gas treatment system 1, an electrostatic precipitator 10 for trapping the impurities contained in the combustion exhaust gas is arranged upstream of the CO2 separation section. In addition, due to the corona discharge in the electrostatic precipitator 10, ozone (O3) can be generated from the oxygen molecules (O2) contained in the combustion exhaust gas. The generated ozone flows downstream from the electrostatic precipitator 10 together with the combustion exhaust gas treated by the electrostatic precipitator 10. Since ozone is a compound with high oxidation ability, resin packages, separation membranes made of polymer materials, etc. provided in the flow path in the gas treatment system 1 may deteriorate. Therefore, the gas treatment system 1 includes constituent components for treating ozone to reduce the ozone concentration. That is, the gas treatment system 1 treats, for example, the ozone contained in the combustion exhaust gas. In addition, the impurities in the combustion exhaust gas are not limited to soot.

[0045] As Figure 1 shown, the gas treatment system 1 includes an electrostatic precipitator 10, a first flow path 21, a storage tank 30, a second flow path 22, a third flow path 23, a first regulating valve 40, a first detection section 51, and a control section 60. In addition, the gas treatment system 1 may include a second detection section 52, a third detection section 53, a blower 71, a heat exchanger 72 for heat removal, a denitration and desulfurization device 73, a separation membrane module 80, and a pressure reducing pump 82. In addition, the gas treatment system 1 may further include other constituent components such as an energy saver or a filter for adsorbing impurities. In addition, the separation membrane module is an example of a "CO2 separation section". Other examples of the CO2 separation section can include a CO2 absorption tower that brings an absorption liquid (release liquid) into contact with the combustion exhaust gas and recovers the CO2 absorbed by the absorption liquid. Hereinafter, the constituent components included in the gas treatment system 1 will be described.

[0046] <Electrostatic Precipitator 10>

[0047] The electrostatic precipitator 10 is connected to the engine 100E via a pipe 11, for example. The electrostatic precipitator 10 traps impurities in the combustion exhaust gas supplied from the engine 100E. For example, combustion exhaust gas at a temperature of over 300 degrees is supplied from the engine 100E to the electrostatic precipitator 10. The flow rate of the combustion exhaust gas supplied from the engine 100E to the electrostatic precipitator 10 is hereinafter referred to as "the first flow rate F1".

[0048] The electrostatic precipitator 10 has a discharge electrode, a collecting electrode, and a collecting chamber that houses the discharge electrode and the collecting electrode. By applying a high voltage between the discharge electrode and the collecting electrode, a corona discharge occurs in the relative space where the discharge electrode and the collecting electrode face each other. As a result, the impurities in the combustion exhaust gas introduced into the collecting chamber become charged. In addition, the charged impurities are trapped by the collecting electrode. Due to the corona discharge generated between the discharge electrode and the collecting electrode, ozone can be generated from oxygen molecules in the impurities.

[0049] <First flow path 21>

[0050] The first flow path 21 is a flow path through which the combustion exhaust gas passing through the electrostatic precipitator 10 flows. The combustion exhaust gas flowing through the first flow path 21 contains ozone generated inside the electrostatic precipitator 10. As Figure 1 shown, the first flow path 21 connects the electrostatic precipitator 10 and the storage tank 30. As an example of the first flow path 21, a pipe with excellent corrosion resistance can be cited. In addition, a blower 71 such as a fan can be arranged in the first flow path 21. By blowing the combustion exhaust gas flowing through the first flow path 21 with the blower 71, the flow velocity of the combustion exhaust gas downstream can be increased.

[0051] <Storage tank 30>

[0052] The storage tank 30 temporarily stores the combustion exhaust gas flowing through the first flow path 21. For example, the combustion exhaust gas introduced into the storage tank 30 stays in the storage tank 30 for a time determined by the first flow rate F1 and the like. Here, the decomposition rate of ozone in the combustion exhaust gas varies according to the temperature conditions to which the ozone is exposed. Specifically, when ozone is exposed to a relatively high-temperature environment, the decomposition rate of ozone is fast. On the other hand, when ozone is exposed to a relatively low-temperature environment, the decomposition rate of ozone is slow. For example, as Figure 2 shown, the decomposition rate of ozone at a temperature of about 350 degrees is faster than the decomposition rate of ozone at a temperature of about 250 degrees.

[0053] Combustion exhaust gas is introduced into the storage tank 30 while maintaining a high temperature when discharged from the engine 100E. By temporarily retaining such high-temperature combustion exhaust gas in the storage tank 30, the temperature of the combustion exhaust gas can be utilized to decompose ozone. Therefore, the ozone concentration in the combustion exhaust gas can be reduced. That is, the ozone concentration can be reduced without additionally supplying thermal energy from a heater to the ozone. Additionally, even when a heater is used, the combustion exhaust gas has a relatively high temperature before being heated by the heater. Therefore, the energy consumption for raising the temperature of the combustion exhaust gas to a desired temperature can be reduced. Consequently, the energy consumption during the operation of the gas treatment system 1 can be reduced.

[0054] As Figure 3 shown, the storage tank 30 includes a storage section 31 for temporarily storing combustion exhaust gas containing ozone, an inlet pipe 32 for introducing the combustion exhaust gas into the storage section 31, and an outlet pipe 33 for discharging the combustion exhaust gas from the storage section 31.

[0055] The inlet pipe 32 is connected to the first flow path 21. The outlet pipe 33 is connected to the second flow path 22. Further, preferably, the inlet pipe 32 is disposed near the bottom wall of the storage section 31, and the outlet pipe 33 is disposed near the upper wall of the storage section 31. In this way, by disposing the outlet pipe 33 above the inlet pipe 32 and increasing the height difference between the outlet pipe 33 and the inlet pipe 32, the residence time of the combustion exhaust gas in the storage section 31 can be extended. As a result, the ozone concentration in the combustion exhaust gas can be further reduced.

[0056] However, the configuration of the storage tank 30 is not limited thereto. Another example can be a configuration of a spiral flow path in which the combustion exhaust gas introduced into the storage section 31 from the inlet pipe 32 flows spirally along the inner wall of the storage section 31, for example. By providing a spiral flow path in the storage section 31, the residence time of the combustion exhaust gas in the storage section 31 can be extended.

[0057] <Second Flow Path 22>

[0058] The second flow path 22 is a flow path through which the combustion exhaust gas passing through the storage tank 30 flows. As Figure 1 shown, the second flow path 22 connects the storage tank 30 and the separation membrane module 80. An example of the second flow path 22 can be a pipe with excellent corrosion resistance.

[0059] The heat exchanger 72 for heat removal can be disposed in the second flow path 22. The heat exchanger 72 for heat removal reduces the temperature of the combustion exhaust gas toward the separation membrane module 80 through heat exchange between the combustion exhaust gas and the refrigerant. Therefore, the temperature of the combustion exhaust gas can be reduced to a relatively low temperature range below 100 degrees. As a result, damage and deterioration of the separation membrane module 80 due to the introduction of high-temperature combustion exhaust gas can be suppressed.

[0060] In addition, the denitration and desulfurization device 73 may be arranged in the second flow path 22. Figure 1 In the example shown, the denitration and desulfurization device 73 is arranged downstream of the heat exchanger 72 for heat removal. However, the position of the denitration and desulfurization device 73 is not limited thereto. For example, the denitration and desulfurization device 73 may be arranged upstream of the electrostatic precipitator 10.

[0061] The denitration and desulfurization device 73 removes nitrogen oxides (NOx) and sulfur oxides (SOx) from the combustion exhaust gas directed to the separation membrane module 80. Thereby, the concentrations of NOx and SOx in the combustion exhaust gas introduced into the separation membrane module 80 can be reduced. As a result, NOx and SOx in the combustion exhaust gas are adsorbed on the separation membrane of the separation membrane module 80, and the CO2 separation operation of the separation membrane module 80 can be inhibited.

[0062] <Third Flow Path 23>

[0063] The third flow path 23 is a flow path branched from the second flow path 22. In addition, the third flow path 23 returns at least a part of the combustion exhaust gas flowing through the second flow path 22 to the first flow path 21. That is, the third flow path 23 returns the combustion exhaust gas passing through the storage tank 30 to the first flow path 21. Therefore, the combustion exhaust gas temporarily passing through the storage tank 30 can be introduced into the storage tank 30 again. As a result, the residence time of the combustion exhaust gas in the storage tank 30 can be extended. The combustion exhaust gas returned to the first flow path 21 via the third flow path 23 is referred to as "reflux gas". The flow rate of the reflux gas is hereinafter referred to as "second flow rate F2".

[0064] As an example of the third flow path 23, a pipe with excellent corrosion resistance can be cited. The third flow path 23 merges with the first flow path 21 at a predetermined position upstream of the blower 71. Therefore, the flow velocity of the reflux gas can be increased. However, the merging position of the third flow path 23 and the first flow path 21 is not limited thereto.

[0065] <First Control Valve 40>

[0066] The first control valve 40 adjusts the opening degree of the third flow path 23. That is, by adjusting the opening degree of the third flow path 23 with the first control valve 40, the second flow rate F2 related to the reflux gas is adjusted. The opening degree of the first control valve 40 is controlled by the control unit 60. Therefore, the first control valve 40 has a processing unit for processing the control signal from the control unit 60.

[0067] As an example of the first control valve 40, a two-way valve having two ports and a valve body for opening and closing the internal space connecting the two ports can be cited. However, the first control valve 40 may have a structure other than this.

[0068] <First Detection Unit 51>

[0069] The first detection unit 51 detects a first flow rate F1 related to the combustion exhaust gas supplied to the electrostatic precipitator 10. When the reflux gas does not reflux to the first flow path 21, the first flow rate F1 corresponds to the flow rate of the combustion exhaust gas flowing through the electrostatic precipitator 10 and into the storage tank 30. The first detection unit 51 outputs a detection signal corresponding to the detected first flow rate F1 to the control unit 60.

[0070] Examples of the first detection unit 51 include flow sensors such as electromagnetic flow meters, thermal flow meters, and ultrasonic flow meters. However, the structure of the first detection unit 51 is not limited to this. Figure 1 The shown first detection unit 51 is arranged upstream of the electrostatic precipitator 10. However, the first detection unit 51 can also be arranged downstream of the electrostatic precipitator 10.

[0071] <Second detection unit 52>

[0072] The second detection unit 52 detects the temperature of the storage tank 30. From the temperature detected by the second detection unit 52, the temperature of the combustion exhaust gas stored in the storage tank 30 (i.e., the ambient temperature of ozone) can be estimated. The second detection unit 52 outputs a detection signal corresponding to the detected temperature to the control unit 60. Examples of the second detection unit 52 include temperature sensors such as resistance temperature detectors, linear resistors, and thermistors. However, the structure of the second detection unit 52 is not limited to this.

[0073] <Third detection unit 53>

[0074] The third detection unit 53 detects a second flow rate F2 related to the reflux gas flowing through the third flow path 23. The third detection unit 53 outputs a detection signal corresponding to the detected second flow rate F2 to the control unit 60. Examples of the third detection unit 53 include flow sensors such as electromagnetic flow meters, thermal flow meters, and ultrasonic flow meters. However, the structure of the third detection unit 53 is not limited to this. As Figure 1 shown, the third detection unit 53 is arranged in the third flow path 23 at a position closer to the first flow path 21 than the first regulating valve 40.

[0075] <Separation membrane module 80>

[0076] The separation membrane module 80 separates CO2 from the combustion exhaust gas. The separation membrane module 80 includes a separation membrane and a container housing the separation membrane. The separation membrane is, for example, a polymer membrane that selectively permeates CO2. Examples of the polymer membrane can include a hollow fiber membrane bundle formed by combining hundreds to hundreds of thousands of hollow fiber membranes.

[0077] The combustion exhaust gas supplied to the separation membrane module 80 is introduced into the inner space of the hollow fiber membrane bundle through the opening on one side of the hollow fiber membrane bundle. At this time, CO2 in the combustion exhaust gas permeates through the hollow fiber membrane and moves to the outer space of the hollow fiber membrane bundle. That is, CO2 in the combustion exhaust gas permeates through the separation membrane. The gas discharged from the separation membrane module 80 after passing through the separation membrane is called "permeate gas". The permeate gas is discharged from the first discharge port provided on the container housing the separation membrane.

[0078] In contrast, other components in the combustion exhaust gas are introduced into the internal space of the hollow fiber membrane bundle through the opening on one side of the hollow fiber membrane bundle, and then discharged through the opening on the other side of the hollow fiber membrane bundle. That is, other components in the combustion exhaust gas do not permeate through the separation membrane. The gas discharged from the separation membrane module 80 without passing through the separation membrane is called "non-permeate gas". The non-permeate gas is discharged from the second discharge port provided on the container housing the separation membrane. In addition, the non-permeate gas sometimes contains CO2 that does not permeate through the separation membrane.

[0079] The vacuum pump 82 can be connected to the first discharge port of the separation membrane module 80. By using the vacuum pump 82 to reduce the pressure on the first discharge port side of the separation membrane module 80, a higher pressure difference can be generated inside and outside the separation membrane. Thereby, the CO2 separation function of the separation membrane can be improved.

[0080] <Control unit 60>

[0081] The control unit 60 controls various operations in the gas treatment system 1. As Figure 4 shown, the control unit 60 is communicably connected to the first regulating valve 40, the first detection unit 51, the second detection unit 52, and the third detection unit 53, respectively.

[0082] The control unit 60 is an information processing device including, for example, an arithmetic processing unit 61, a storage unit 62, and a communication unit 63. The arithmetic processing unit 61, the storage unit 62, and the communication unit 63 are electrically connected to each other through a bus 68, respectively.

[0083] The arithmetic processing unit 61 is a processor that executes the control and processing of various operations of the control unit 60. An example of the arithmetic processing unit 61 can be a CPU (Central Processing Unit). In addition, the arithmetic processing unit 61 can also be composed of other electronic circuits that implement the same functions as a processor such as a CPU.

[0084] The storage unit 62 stores programs executed by the arithmetic processing unit 61 and various data required for executing the programs. An example of the storage unit 62 can be a non-volatile storage medium such as a ROM (Read Only Memory).

[0085] In addition, the storage unit 62 stores, for example, data related to the volume of the storage tank 30 and data for calculating various threshold values set by the arithmetic processing unit 61. The storage unit 62 stores data related to the temporal change of the ozone concentration under multiple different temperature conditions. For example, the storage unit 62 stores data including the ozone concentration C1-1 at a temperature of 250 degrees and an elapsed time of 1 second, the ozone concentration C1-2 at an elapsed time of 2 seconds, ···, the ozone concentration C1-n at an elapsed time of n seconds, the ozone concentration C2-1 at a temperature of 350 degrees and an elapsed time of 1 second, the ozone concentration C2-2 at an elapsed time of 2 seconds, ···, the ozone concentration C2-n at an elapsed time of n seconds, and so on. The data stored in the storage unit 62 can be a theoretical value related to the temporal change of the ozone concentration or a measured value measured in advance. The data related to the temporal change of the ozone concentration under multiple different temperature conditions is hereinafter referred to as "ozone concentration data DO".

[0086] The communication unit 63 is a communication interface including components such as a communication circuit and an antenna for communicating with the first regulating valve 40, the first detection unit 51, the second detection unit 52, and the third detection unit 53 respectively.

[0087] Next, various functions of the arithmetic processing unit 61 will be described. As Figure 4 shown, the arithmetic processing unit 61 functions as various units such as an acquisition unit 611, a residence time calculation unit 612, a first threshold calculation unit 613, a first determination unit 614, a second threshold calculation unit 615, a second determination unit 616, an opening degree adjustment unit 617, and a third determination unit 618. The arithmetic processing unit 61 executes the program stored in the storage unit 62 to cause the control unit 60 to function as the above-described various units. The program can be stored in a computer-readable storage medium and provided, or can be provided via a communication network such as the Internet.

[0088] The acquisition unit 611 receives detection signals from the first detection unit 51, the second detection unit 52, and the third detection unit 53 respectively through the communication unit 63. Thereby, the acquisition unit 611 acquires various information such as the first flow rate F1 related to the combustion exhaust gas, the second flow rate F2, and the temperature K1 of the storage tank 30 respectively.

[0089] The residence time calculation unit 612 calculates the residence time T1 of the combustion exhaust gas in the storage tank 30 based on the first flow rate F1 acquired by the acquisition unit 611 and the volume V of the storage tank 30. The residence time calculation unit 612 calculates the residence time T1, for example, by dividing the volume V of the storage tank 30 by the flow rate value corresponding to the first flow rate F1.

[0090] The first threshold calculation unit 613 calculates a first threshold Th1 related to the temperature required to reduce the ozone concentration in the combustion exhaust gas to the target concentration at the moment after the residence time T1 has elapsed. When calculating the first threshold Th1, the first threshold calculation unit 613 refers to the information on the residence time T1 input from the residence time calculation unit 612 and the ozone concentration data DO stored in the storage unit 62. Here, the "target concentration" can be set appropriately. Additionally, the "target concentration" can also be the relative value of the target concentration when the ozone concentration in the combustion exhaust gas at the moment of starting to introduce it into the storage tank 30 is set to "1".

[0091] For example, when the target concentration is set to "0.01", the first threshold calculation unit 613 uses the ozone concentration data DO to calculate the first threshold Th1 required to reduce the ozone concentration in the combustion exhaust gas to "0.01" during the residence time T1.

[0092] The first determination unit 614 determines whether the temperature K1 of the storage tank 30 acquired by the acquisition unit 611 is equal to or higher than the first threshold Th1. That is, the first determination unit 614 determines whether the temperature of the storage tank reaches the first threshold Th1.

[0093] The second threshold calculation unit 615 calculates a second threshold Th2 related to the time required for the ozone concentration in the combustion exhaust gas to reach the target concentration under the temperature condition of the temperature K1 of the storage tank 30. When calculating the second threshold Th2, the second threshold calculation unit 615 refers to the information on the residence time T1 input from the residence time calculation unit 612 and the ozone concentration data DO stored in the storage unit 62.

[0094] The second determination unit 616 determines whether the residence time T1 is equal to or longer than the second threshold Th2. That is, the second determination unit 616 determines whether it is necessary to introduce the reflux gas into the storage tank 30 to extend the residence time of the combustion exhaust gas.

[0095] In the case where it is necessary to extend the residence time of the combustion exhaust gas, the opening degree adjustment unit 617 adjusts the opening degree of the first regulating valve 40 so that the new residence time T3 is the reflux gas required to be equal to or longer than the second threshold Th2 and introduced into the storage tank 30.

[0096] Specifically, the opening degree adjustment unit 617 calculates the additional flow rate value FL required for the combustion exhaust gas to stay in the storage tank 30 during the residence time T3. Additionally, the opening degree adjustment unit 617 adjusts the opening degree of the first regulating valve 40 so that the second flow rate F2 related to the reflux gas becomes the flow rate value FL.

[0097] The third determination unit 618 refers to the information of the second flow rate F2 obtained by the acquisition unit 611, and determines whether the second flow rate F2 is equal to or higher than the flow rate value FL. When the second flow rate F2 is equal to or higher than the flow rate value FL, it is presumed that the reflux gas stays in the storage tank 30 for at least the residence time T3. Therefore, the ozone concentration in the combustion exhaust gas can be further reduced.

[0098] <Opening adjustment operation of the first regulating valve 40>

[0099] Next, with reference to Figure 5 , the process of the opening adjustment operation of the first regulating valve 40 in the control unit 60 will be described. Figure 5 is a flowchart showing an example of the process of the opening adjustment operation of the first regulating valve 40 in the control unit 60. In addition, at the moment when the combustion exhaust gas starts to be introduced, the first regulating valve 40 is closed.

[0100] First, in step S11, the control unit 60 acquires the information of the first flow rate F1 related to the combustion exhaust gas supplied to the electrostatic precipitator 10 and the temperature K1 of the storage tank 30 from the first detection unit 51 and the second detection unit 52.

[0101] Next, in step S12, the control unit 60 calculates the residence time T1 of the combustion exhaust gas in the storage tank 30 based on the first flow rate F1 and the volume V of the storage tank 30.

[0102] Next, in step S13, at the moment when the residence time T1 has elapsed, the control unit 60 calculates the first threshold Th1 related to the temperature required to reduce the ozone concentration in the combustion exhaust gas to the target concentration.

[0103] Next, in step S14, the control unit 60 determines whether the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1. According to the determination result, when the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1, the control unit 60 does not output a control signal to the first regulating valve 40. That is, the first regulating valve 40 maintains the closed state. The reflux gas is not introduced into the storage tank 30.

[0104] In contrast, according to the determination result in step S14, when the temperature K1 of the storage tank 30 is lower than the first threshold Th1, then in step S15, the control unit 60 calculates the second threshold Th2 related to the time required for the ozone concentration in the combustion exhaust gas to reach the target concentration under the temperature condition of the temperature K1 of the storage tank 30.

[0105] Then, in step S16, the control unit 60 determines whether the residence time T1 is equal to or higher than the second threshold Th2. According to the determination result, when the residence time T1 is equal to or higher than the second threshold Th2, the control unit does not output a control signal to the first regulating valve 40. That is, the first regulating valve 40 maintains the closed state. The reflux gas is not introduced into the storage tank 30.

[0106] In contrast, according to the determination result in step S16, when the residence time T1 is lower than the second threshold Th2, in step S17, the control unit 60 calculates the flow rate value FL of the reflux gas required for the new residence time T3 to be equal to or higher than the second threshold Th2. In addition, the control unit 60 adjusts the opening degree of the first regulating valve 40 so that the second flow rate F2 related to the reflux gas becomes the flow rate value FL. Specifically, the control unit 60 outputs a control signal representing the opening degree information to the first regulating valve 40. Therefore, the reflux gas flows through the third flow path 23 to the first flow path 21 and is introduced into the storage tank 30. As a result, the residence time related to the reflux gas is extended. Determine whether the second flow rate F2 is equal to or higher than the flow rate value FL.

[0107] Next, in step S18, the control unit 60 determines whether the second flow rate F2 obtained from the third detection unit 53 is equal to or higher than the flow rate value FL. According to the determination result, when the second flow rate F2 is equal to or higher than the flow rate value FL, the opening degree of the first regulating valve 40 is maintained. In contrast, when the second flow rate F2 is less than the flow rate value FL, the series of steps of step S17 and step S18 are repeated until the second flow rate F2 becomes equal to or higher than the flow rate value FL.

[0108] As described above, by controlling the flow rate value of the reflux gas by the control unit 60, the accuracy of further increasing the ozone concentration to the target concentration can be improved.

[0109] Second Embodiment

[0110] <Overall Configuration>

[0111] Refer to Figure 6 , which shows a configuration example of the gas treatment system 1A according to the second embodiment. Figure 6 It is a schematic diagram showing an example of the overall configuration of the gas treatment system 1A according to the second embodiment. In addition, in the second embodiment, the same reference numerals are given to the constituent parts that are the same as those in the first embodiment, and the description is appropriately omitted.

[0112] As Figure 6 shown, the difference between the gas treatment system 1A according to the second embodiment and the first embodiment is that it includes a heater 91. The control unit 60 of the gas treatment system 1A can also function as a heater temperature control unit. In addition, other constituent components included in the gas treatment system 1A according to the second embodiment may be the same as those of the gas treatment system 1 according to the first embodiment.

[0113] The heater 91 raises the temperature inside the storage tank 30. That is, the heater 91 heats the combustion exhaust gas containing ozone introduced into the storage tank 30. The configuration of the heater 91 is not limited as long as it can raise the temperature inside the storage tank 30.

[0114] For example, when an energy saver or the like is disposed upstream of the storage tank 30 and the temperature of the combustion exhaust gas when introduced into the storage tank 30 is lower than the temperature when discharged from the engine 100E, the combustion exhaust gas can be heated by the heater 91. As a result, the thermal energy of the ozone applied to the combustion exhaust gas increases, promoting the decomposition of the ozone. As a result, the ozone concentration can be reduced.

[0115] <Control operation of heater temperature>

[0116] Next, with reference to Figure 7 , the control operation of the heater temperature in the control unit 60 will be described. Figure 7 is a flowchart for explaining the control operation of the heater temperature in the control unit 60.

[0117] First, in step S31, the control unit 60 obtains information on the first flow rate F1 related to the combustion exhaust gas supplied to the electrostatic precipitator 10 and the temperature K1 of the storage tank 30 from the first detection unit 51 and the second detection unit 52.

[0118] Next, in step S32, the control unit 60 calculates the residence time T1 of the combustion exhaust gas in the storage tank 30 based on the first flow rate F1 and the volume V of the storage tank 30.

[0119] Next, in step S33, at the moment when the residence time T1 has elapsed, the control unit 60 calculates a first threshold Th1 related to the temperature required to reduce the ozone concentration in the combustion exhaust gas to the target concentration.

[0120] Next, in step S34, the control unit 60 determines whether the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1. Based on the determination result, when the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1, the control unit 60 does not output a control signal to the heater 91. That is, the combustion exhaust gas in the storage tank 30 is not heated.

[0121] According to the determination result in step S34, when the temperature K1 of the storage tank 30 is lower than the first threshold Th1, then in step S35, the control unit 60 calculates the heating amount Q1 required for the ozone concentration in the combustion exhaust gas to reach the target concentration at the moment when the residence time T1 has elapsed. In addition, the control unit 60 outputs a control signal related to the heating amount Q1 to the heater 91. The heater 91 performs a heating operation according to the control signal from the control unit 60.

[0122] Next, in step S36, the control unit 60 obtains the temperature information of the storage tank 30 from the second detection unit 52 again. Further, based on the obtained temperature information, the control unit 60 determines whether the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1. As a determination result, when the temperature K1 of the storage tank 30 is equal to or higher than the first threshold Th1, the control unit 60 stops the heating operation of the heater 91.

[0123] According to the determination result in step S36, when the temperature K1 of the storage tank 30 is lower than the first threshold Th1, a series of steps of step S35 and step S36 are repeated.

[0124] In this way, the control unit 60 operates the heater 91 as needed. Therefore, compared with a configuration in which the combustion exhaust gas in the storage tank 30 is always heated by the heater 91, the energy consumed by the operation of the gas treatment system 1A can be reduced.

[0125] Third Embodiment

[0126] <Overall Configuration>

[0127] Refer to Figure 8 , which shows a configuration example of the gas treatment system 1B according to the third embodiment. Figure 8 is a schematic diagram showing an example of the overall configuration of the gas treatment system 1B according to the third embodiment. In addition, in the third embodiment, the same reference numerals are given to the constituent parts that are the same as those in the first embodiment and the second embodiment, and the description is appropriately omitted.

[0128] As Figure 8 shown, the gas treatment system 1B according to the third embodiment is different from the above-described embodiments in that it includes a fourth flow path 24 connected to the engine 100E and a second regulating valve 45. The control unit 60 of the gas treatment system 1B can also function as a device for controlling the opening and closing of the second regulating valve 45 based on the first flow rate F1 acquired by the first detection unit 51 and the temperature of the storage tank 30 acquired by the second detection unit 52. In addition, other constituent components included in the gas treatment system 1B according to the third embodiment may be the same as those in the above-described embodiments.

[0129] The fourth flow path 24 is a flow path through which the combustion exhaust gas discharged from the engine 100E flows, which is different from the first flow path 21. The fourth flow path 24 is connected to the storage tank 30. Figure 8 The fourth flow path 24 shown merges with the first flow path 21 after passing through the inside of the storage tank 30. However, the fourth flow path 24 does not have to pass through the inside of the storage tank 30 and may be in contact with the storage tank 30. The fourth flow path 24 may not merge with the first flow path 21.

[0130] The high-temperature combustion exhaust gas discharged from the engine 100E, for example, at a temperature exceeding 300 degrees, flows through the fourth flow path 24. By providing the fourth flow path 24, it is possible to warm the combustion exhaust gas retained in the storage tank 30 without using a heating device such as the heater 91. Therefore, it is possible to reduce the energy consumption during the operation of the gas treatment system 1B while reducing the ozone concentration in the combustion exhaust gas.

[0131] The second regulating valve 45 regulates the opening and closing of the fourth flow path 24. The opening and closing operation of the second regulating valve 45 can also be controlled by the control unit 60. For example, when it is determined that the ozone concentration has not been reduced to the target concentration at the residence time T1 at the temperature of the storage tank 30, the control unit 60 controls to open the second regulating valve 45. Therefore, the high-temperature combustion exhaust gas flows through the fourth flow path 24, and the storage tank 30 is warmed. Along with this, the combustion exhaust gas retained in the storage tank 30 is warmed, and the ozone concentration in the combustion exhaust gas is reduced.

[0132] As described above, the embodiments have been described, but the above embodiments are presented as examples, and the above embodiments do not limit the present invention. The above embodiments can be implemented in various other ways, and various combinations, omissions, substitutions, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the same scope as the invention described in the claims.

Claims

1. A gas treatment system, comprising: An electrostatic precipitator for collecting impurities in combustion exhaust gas containing CO2; A first flow path through which the combustion exhaust gas containing ozone flows after passing through the electrostatic precipitator; A storage tank for temporarily storing the combustion exhaust gas flowing through the first flow path; A second flow path through which the combustion exhaust gas flowing through the storage tank flows; A third flow path branched from the second flow path to return at least a part of the combustion exhaust gas flowing through the second flow path to the first flow path; A first regulating valve for adjusting the opening degree of the third flow path; A first detection unit for detecting a first flow rate related to the combustion exhaust gas supplied to the electrostatic precipitator; and A control unit for controlling the opening degree of the first regulating valve based on the first flow rate detected by the first detection unit.

2. The gas treatment system according to claim 1, further comprising a second detection unit for detecting the temperature of the storage tank, wherein the control unit controls the opening degree of the first regulating valve based on the first flow rate detected by the first detection unit and the temperature of the storage tank detected by the second detection unit to adjust a second flow rate flowing through the third flow path.

3. The gas treatment system according to claim 2, wherein the control unit stores ozone concentration data related to the time change of each ozone concentration under a plurality of different temperature conditions, and controls the opening degree of the first regulating valve based on the first flow rate detected by the first detection unit, the temperature of the storage tank detected by the second detection unit, and the ozone concentration data to adjust the second flow rate flowing through the third flow path.

4. The gas treatment system according to claim 1 or 2, wherein the first flow path is connected to an engine as a combustion exhaust gas emission source.

5. The gas treatment system according to claim 1 or 2, further comprising a heater for increasing the temperature in the storage tank.

6. The gas treatment system according to claim 2, further comprising: A fourth flow path connected to the storage tank; and A second regulating valve for adjusting the opening and closing of the fourth flow path, wherein the combustion exhaust gas discharged from the combustion exhaust gas discharge source flows to the first flow path and the fourth flow path respectively, and the control unit controls the opening and closing of the second regulating valve based on the first flow rate detected by the first detection unit and the temperature of the storage tank detected by the second detection unit.

7. The gas treatment system according to claim 1 or 2, further comprising a CO2 separation unit for separating CO2 from the combustion exhaust gas flowing through the second flow path.

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