Gas processing system

Abstract

This disclosure provides a technology for controlling the flow rate and pressure of recycled gas in a gas processing system using a simple configuration. [Solution] A gas processing system comprising: a first gas separation unit equipped with a first separation membrane; a second gas separation unit connected in series with the first gas separation unit and equipped with a second separation membrane; a raw material gas line supplying raw material gas to the first gas separation unit; a recycling line returning the second unpermeated gas from the second gas separation unit to the raw material gas line; a third transfer unit located in the recycling line and sending the second unpermeated gas to the raw material gas line; a control valve provided downstream of the third transfer unit in the recycling line; and a control unit that controls the third transfer unit based on the first pressure of the supply gas in the second gas separation unit and the second pressure of the second unpermeated gas, and controls the control valve based on the third pressure of the raw material gas and the fourth pressure of the recycled gas in the recycling line.

Description

Technical Field

[0001] The present disclosure relates to a gas treatment system.

Background Art

[0002] Patent Document 1 discloses a membrane-type nitrogen production facility that has a primary membrane and a secondary membrane and obtains nitrogen gas from combustion exhaust gas. Patent Document 1 discloses that the primary membrane separates combustion exhaust gas into a primary membrane permeation gas that is discharged into the atmosphere and a primary membrane non-permeation gas. Further, Patent Document 1 discloses that the secondary membrane separates the primary membrane permeation gas into a secondary membrane permeation gas that is refluxed and circulated to the combustion exhaust gas supplied from a gas compressor and a secondary membrane non-permeation gas.

[0003] Patent Document 2 discloses a gas treatment system including a first purification unit that purifies a raw material gas supplied from a buffer tank to produce a first purified gas and discharges a first waste gas, and a second purification unit that purifies the first purified gas to produce a second purified gas and discharges a second waste gas. Patent Document 2 discloses that the gas treatment system further includes a third purification unit that purifies the first waste gas to produce a third purified gas. Patent Document 2 discloses that it includes a first recovery line that guides the second waste gas to the buffer tank and a second recovery line that guides the third purified gas to the buffer tank.

[0004] Patent Document 3 discloses a methane concentration device for recovering a concentrated gas with an increased methane concentration from a raw material gas mainly composed of methane and gas A having a smaller molecular diameter than methane. Patent Document 3 discloses that the methane concentration device includes a first separation membrane, a second separation membrane, a first flow path that guides the raw material gas to the first separation membrane, and a second flow path that guides the non-permeation gas that did not permeate the first separation membrane among the raw material gas guided through the first flow path to the second separation membrane.

[0005] Patent Document 4 discloses a gas treatment system that supplies a raw material mixed gas containing at least carbon dioxide and methane to a gas separation membrane unit and enriches the methane contained in the raw material mixed gas. Patent Document 4 discloses that the gas treatment system comprises a first gas separation membrane unit and a second gas separation membrane unit. Patent Document 4 discloses that the system comprises a second permeate gas recycling line connecting the permeate gas outlet of the second gas separation membrane unit and the raw material mixed gas supply line. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-109914 [Patent Document 2] Japanese Patent Publication No. 2015-196157 [Patent Document 3] Japanese Patent Publication No. 2008-260739 [Patent Document 4] International Publication No. 2024 / 014493 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In a gas processing system that separates a desired gas from a raw material gas, gas separation units equipped with separation membranes are sometimes connected in series, and the unpermeated gas from the downstream gas separation unit is mixed with the raw material gas and supplied to the upstream gas separation unit for recycling. In a gas processing system, when the unpermeated gas from the downstream gas separation unit is mixed with the raw material gas, it is required to appropriately control the flow rate and pressure of the unpermeated gas in the downstream gas separation unit that is to be recycled.

[0008] This disclosure provides a technology for controlling the flow rate and pressure of recycled gas in a gas treatment system in which unpermeated gas from a downstream gas separation unit is mixed with raw material gas and supplied to an upstream gas separation unit for recycling, using a simple configuration. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, a first gas separation unit comprising a first separation membrane, to which a raw material gas is supplied, and to separate the supplied raw material gas into a first permeate gas that permeates through the first separation membrane and a first unpermeated gas that is discharged without permeating through the first separation membrane; a second gas separation unit connected in series with the first gas separation unit, comprising a second separation membrane, to which the first permeate gas is supplied, and to separate the supplied first permeate gas into a second permeate gas that permeates through the second separation membrane and a second unpermeated gas that is discharged without permeating through the second separation membrane; a raw material gas line for supplying the raw material gas to the first gas separation unit; a recycling line for returning the second unpermeated gas to the raw material gas line; a first transfer unit for supplying the first permeate gas in the first gas separation unit to the second gas separation unit; a second transfer unit for discharging the second permeate gas in the second gas separation unit to the outside; and the recycling line A gas processing system is provided, comprising: a third transfer unit located in the recycling line and sending the second impermeable gas to the raw material gas line; a first pressure gauge for measuring the pressure of the first permeable gas supplied to the second gas separation unit; a second pressure gauge for measuring the pressure of the second impermeable gas discharged from the second gas separation unit; a third pressure gauge in the raw material gas line for measuring the pressure of the raw material gas; a fourth pressure gauge downstream of the third transfer unit in the recycling line for measuring the pressure of the second impermeable gas; a control valve located downstream of the third transfer unit in the recycling line and upstream of the fourth pressure gauge; and a control unit that controls the third transfer unit based on a first pressure measured by the first pressure gauge and a second pressure measured by the second pressure gauge, and controls the control valve based on a third pressure measured by the third pressure gauge and a fourth pressure measured by the fourth pressure gauge. [Effects of the Invention]

[0010] According to this disclosure, in a gas treatment system in which unpermeated gas from a downstream gas separation unit is mixed with raw material gas and supplied to an upstream gas separation unit for recycling, the flow rate and pressure of the recycled gas can be controlled with a simple configuration. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram illustrating the schematic configuration of a gas processing system according to the first embodiment. [Figure 2] Figure 2 is a hardware configuration diagram illustrating the hardware configuration of the control unit in the gas processing system according to the first embodiment. [Figure 3] Figure 3 is a functional configuration diagram illustrating the functional configuration of the control unit in the gas processing system according to the first embodiment. [Figure 4] Figure 4 is a flowchart illustrating the processing performed by the control unit in the gas processing system according to the first embodiment. [Figure 5] Figure 5 is a diagram illustrating the schematic configuration of the gas processing system according to the second embodiment. [Figure 6] Figure 6 is a functional configuration diagram illustrating the functional configuration of the control unit in the gas processing system according to the second embodiment. [Figure 7] Figure 7 is a flowchart illustrating the processing performed by the control unit in the gas processing system according to the second embodiment. [Figure 8] Figure 8 is a diagram illustrating the schematic configuration of the gas processing system according to the third embodiment. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure will be described below with reference to the attached drawings. Note that, in the description and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from that of actual parts.

[0013] <First Embodiment> The gas treatment system according to the first embodiment will be described. The gas treatment system according to the first embodiment includes a first separation membrane, and a first gas separation unit that is supplied with a raw material gas and separates the supplied raw material gas into a first permeated gas that permeates through the first separation membrane and a first unpermeated gas that is discharged without permeating through the first separation membrane. Further, the gas treatment system according to the first embodiment includes a second gas separation unit that is connected in series to the first gas separation unit, includes a second separation membrane, and is supplied with the first permeated gas. The second gas separation unit in the gas treatment system according to the first embodiment separates the supplied first permeated gas into a second permeated gas that permeates through the second separation membrane and a second unpermeated gas that is discharged without permeating through the second separation membrane. Furthermore, the gas treatment system according to the first embodiment includes a raw material gas line that supplies the raw material gas to the first gas separation unit and a recycle line that returns the second unpermeated gas to the raw material gas line. Additionally, the gas treatment system according to the first embodiment includes a first transfer unit that supplies the first permeated gas in the first gas separation unit to the second gas separation unit and a second transfer unit that discharges the second permeated gas in the second gas separation unit to the outside. Also, the gas treatment system according to the first embodiment includes a third transfer unit that is disposed in the recycle line and sends the second unpermeated gas to the raw material gas line. Furthermore, the gas treatment system according to the first embodiment includes a first pressure gauge that measures the pressure of the first permeated gas supplied to the second gas separation unit and a second pressure gauge that measures the pressure of the second unpermeated gas discharged from the second gas separation unit. And the gas treatment system according to the first embodiment includes a control unit that controls the third transfer unit. The control unit in the gas treatment system according to the first embodiment controls the third transfer unit based on the first pressure measured by the first pressure gauge and the second pressure measured by the second pressure gauge.

[0014] The gas treatment system according to the first embodiment will be described in detail using the drawings. FIG. 1 is a diagram for explaining the schematic configuration of a gas treatment system 1 which is an example of the gas treatment system according to the first embodiment.

[0015] The gas treatment system 1 separates carbon dioxide gas from the raw material gas Gm by a gas separation unit. Then, the gas treatment system 1 concentrates the carbon dioxide gas by connecting a plurality of gas separation units in series. Note that the gas treatment system 1 includes two gas separation units, namely a gas separation unit 10 and a gas separation unit 20. And the gas treatment system 1 discharges the concentrated carbon dioxide gas as the recovered gas Ge.

[0016] The raw material gas Gm is, for example, the exhaust gas of an engine that is a power source such as a ship. The carbon dioxide gas recovered as the recovered gas Ge is stored in, for example, a tank or the like.

[0017] The gas treatment system 1 includes the gas separation unit 10 and the gas separation unit 20, transfer units 31, 32, and 33, and a control unit 80. Also, the gas treatment system 1 includes a pressure gauge 51 and a pressure gauge 52. Further, the gas treatment system 1 includes a raw material gas line 61, a connection line 62, an exhaust gas line 63, a gas recovery line 64, and a recycle line 65.

[0018] Details of each component in the gas treatment system 1 will be described.

[0019] (Gas separation unit 10 and gas separation unit 20) Each of the gas separation unit 10 and the gas separation unit 20 separates and discharges the permeated gas containing a large amount of carbon dioxide contained in the gas supplied through the separation membrane, and the unpermeated gas that does not pass through the separation membrane and has a smaller amount of carbon dioxide than the permeated gas.

[0020] The gas separation unit 10 includes a separation membrane 11. The gas separation unit 10 has an unpermeated side space 10S1 and a permeated side space 10S2 inside. The inside of the gas separation unit 10 is divided into the unpermeated side space 10S1 and the permeated side space 10S2 by the separation membrane 11.

[0021] The impermeable space 10S1 in the gas separation unit 10 is connected to the raw material gas line 61 and the exhaust gas line 63. The permeable space 10S2 in the gas separation unit 10 is connected to the connection line 62.

[0022] The gas separation unit 10 is supplied with raw material gas Gm. More specifically, the gas separation unit 10 is supplied with a mixed gas Gc, which is a mixture of raw material gas Gm and recycled gas Gr.

[0023] The non-permeable space 10S1 of the gas separation unit 10 is supplied with raw material gas Gm, or more specifically, mixed gas Gc, which is a mixture of raw material gas Gm and recycled gas Gr. When a differential pressure is generated between the non-permeable space 10S1 and the permeable space 10S2, the separation membrane 11 selectively permeates the carbon dioxide gas contained in the mixed gas Gc (raw material gas Gm) supplied to the non-permeable space 10S1.

[0024] In the gas separation unit 10, the permeate gas Gp1 that has permeated through the separation membrane 11 is discharged into the connection line 62. In the gas separation unit 10, the unpermeated gas Gn1 that has not permeated through the separation membrane 11 is discharged into the exhaust gas line 63.

[0025] The gas separation unit 20 includes a separation membrane 21. The gas separation unit 20 has an impermeable space 20S1 and a permeable space 20S2 inside. The inside of the gas separation unit 20 is divided into the impermeable space 20S1 and the permeable space 20S2 by the separation membrane 21.

[0026] The impermeable space 20S1 in the gas separation unit 20 is connected to the connection line 62 and the recycling line 65. The permeable space 20S2 in the gas separation unit 20 is connected to the gas recovery line 64.

[0027] The gas separation unit 20 is connected in series with the gas separation unit 10. The gas separation unit 20 is supplied with the permeate gas Gp1 that has permeated through the separation membrane in the gas separation unit 10.

[0028] The permeate gas Gp1 that has permeated through the separation membrane in the gas separation unit 10 is supplied to the impermeable space 20S1 of the gas separation unit 20. When a pressure difference is generated between the impermeable space 20S1 and the permeable space 20S2, the separation membrane 21 selectively allows carbon dioxide gas contained in the permeate gas Gp1 supplied to the impermeable space 20S1 to permeate.

[0029] In the gas separation unit 20, the permeate gas Gp2 that has permeated through the separation membrane 21 is discharged to the gas recovery line 64. In the gas separation unit 20, the unpermeated gas Gn2 that has not permeated through the separation membrane 21 is discharged to the recycling line 65.

[0030] Each of the separation membranes 11 and 21 is not particularly limited as long as it is a membrane capable of separating carbon dioxide. The material of each of the separation membranes 11 and 21 may be an organic membrane such as a polymer membrane, or an inorganic membrane such as a zeolite membrane or a silica-based amorphous membrane. The membrane shape of each of the separation membranes 11 and 21 may be a homogeneous membrane, a composite membrane consisting of a homogeneous membrane and a porous membrane, or a porous membrane. The configuration in which the separation membranes are housed in each of the gas separation units 10 and 20 may be a plate-and-frame type or a stacked sheet type, or a spiral type or a hollow fiber type.

[0031] (Transfer section 31, transfer section 32, and transfer section 33) Each of the transfer units 31, 32, and 33 transfers gas. Each of the transfer units 31, 32, and 33 is, for example, a vacuum pump, a pressure reducing pump, or a blower.

[0032] The transfer unit 31 supplies the permeate gas Gp1 that has permeated through the separation membrane 11 in the gas separation unit 10 to the gas separation unit 20. More specifically, the transfer unit 31 aspirates the permeate gas Gp1 that has permeated through the separation membrane 11 in the gas separation unit 10 and discharges it into the impermeable space 20S1 in the gas separation unit 20. The transfer unit 31 is located in the connection line 62.

[0033] The transfer unit 32 discharges the permeate gas Gp2 that has permeated through the separation membrane 21 in the gas separation unit 20 to the outside of the gas treatment system 1 as recovered gas Ge. More specifically, the transfer unit 31 sucks in the permeate gas Gp2 that has permeated through the separation membrane 21 in the gas separation unit 20 and discharges it to the outside of the gas treatment system 1 as recovered gas Ge. The transfer unit 32 is located in the gas recovery line 64.

[0034] The transfer unit 33 sends the unpermeable gas Gn2 that did not permeate the separation membrane 21 in the gas separation unit 20 to the raw material gas line 61. More specifically, the transfer unit 33 aspirates the unpermeable gas Gn2 that did not permeate the separation membrane 21 in the gas separation unit 20 and discharges it to the gas mixing header 70 in the raw material gas line 61. The transfer unit 33 is located in the recycling line 65.

[0035] (Pressure gauge 51 and pressure gauge 52) The pressure gauge 51 is installed between the transfer unit 31 and the gas separation unit 20 in the connection line 62. The pressure gauge 51 measures the pressure of the permeate gas Gp1 on the discharge side of the transfer unit 31. In other words, the pressure gauge 51 measures the pressure of the permeate gas Gp1 supplied to the impermeable space 20S1 in the gas separation unit 20.

[0036] The pressure gauge 52 is installed between the transfer section 33 and the gas separation unit 20 in the recycling line 65. The pressure gauge 52 measures the pressure of the impermeable gas Gn2 on the discharge side of the gas separation unit 20. In other words, the pressure gauge 52 measures the pressure of the impermeable gas Gn2 discharged from the impermeable side space 20S1 in the gas separation unit 20.

[0037] (Raw material gas line 61) The raw material gas line 61 supplies raw material gas Gm to the gas separation unit 10 from outside the gas processing system 1. The raw material gas line 61 connects the gas separation unit 10 to equipment outside the gas processing system 1, such as an engine that discharges exhaust gas. More specifically, the raw material gas line 61 is connected to the impermeable side space 10S1 in the gas separation unit 10. The raw material gas line 61 then supplies raw material gas Gm (mixed gas Gc) to the impermeable side space 10S1 in the gas separation unit 10.

[0038] The gas processing system 1 is equipped with a gas mixing header 70 in the raw gas line 61. The gas mixing header 70 mixes the raw gas Gm with the recycled gas Gr supplied from the recycling line 65. The gas mixing header 70 discharges the mixed gas Gc, which is a mixture of the raw gas Gm and the recycled gas Gr, to the gas separation unit 10.

[0039] (Connection line 62) The connection line 62 supplies the permeate gas Gp1 discharged from the gas separation unit 10 to the impermeable space 20S1 in the gas separation unit 20. The connection line 62 connects the gas separation unit 10 and the gas separation unit 20. More specifically, the connection line 62 connects the permeable space 10S2 in the gas separation unit 10 and the impermeable space 20S1 in the gas separation unit 20.

[0040] The gas processing system 1 includes a transfer unit 31 and a pressure gauge 51 in the connection line 62.

[0041] (Exhaust gas line 63) The exhaust gas line 63 discharges the unpermeable gas Gn1 exhausted from the impermeable space 10S1 in the gas separation unit 10 to the outside of the gas treatment system 1. The exhaust gas line 63 is connected to, for example, a chimney. The unpermeable gas Gn1 flowing through the exhaust gas line 63 is gas that did not permeate the separation membrane 11, and therefore has a low carbon dioxide content.

[0042] (Gas recovery line 64) The gas recovery line 64 discharges the permeate gas Gp2 emitted from the gas separation unit 20 to the outside of the gas treatment system 1. The gas recovery line 64 is connected to, for example, a tank that stores carbon dioxide gas. The gas recovery line 64 is connected to the permeate side space 20S2 in the gas separation unit 20.

[0043] The gas processing system 1 includes a transfer unit 32 in the gas recovery line 64.

[0044] (Recycling line 65) The recycling line 65 returns the unpermeated gas Gn2 discharged from the gas separation unit 20 back to the raw material gas line 61. More specifically, the recycling line 65 connects the impermeable side space 20S1 in the gas separation unit 20 to the gas mixing header 70 in the raw material gas line 61.

[0045] The gas processing system 1 includes a transfer unit 33 in the recycling line 65.

[0046] (Control unit 80) The control unit 80 controls the gas processing system 1. Specifically, the control unit 80 controls the transfer unit 31, the transfer unit 32, and the transfer unit 33, respectively. The control unit 80 also acquires the pressure detection results from the pressure gauge 51 and the pressure gauge 52, respectively.

[0047] In the gas processing system 1, the control unit 80 controls the transfer unit 33 based on the flow rate of the unpermeated gas Gn2 discharged from the gas separation unit 20.

[0048] The hardware configuration of the control unit 80 will now be described. Figure 2 is a hardware configuration diagram illustrating the hardware configuration of the control unit 80 in a gas processing system 1, which is an example of a gas processing system according to the first embodiment.

[0049] The control unit 80 includes a CPU (Central Processing Unit) 81, RAM (Random Access Memory) 82, and ROM (Read Only Memory) 83. The control unit 80 also includes a storage interface 84 and an external interface 85. The CPU 81, RAM 82, ROM 83, storage interface 84, and external interface 85 are each connected to bus B1.

[0050] For example, a storage medium 84a is connected to the storage I / F 84. The transport units 31, 32, and 33, which perform control, are connected to the external I / F 85. In addition, the pressure gauges 51 and 52, which perform measurement, are connected to the external I / F 85.

[0051] The CPU 81 is a processor that performs calculations. The CPU 81 may also be an MPU (Micro Processing Unit). Alternatively, the CPU 81 may be an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). The CPU 81 executes a program, thereby performing each of the processes described herein. The CPU 81 is an arithmetic unit that reads a program (app, application) from a storage device such as ROM 83 or storage medium 84a onto RAM 82 and executes the processing. The CPU 81, RAM 82, and ROM 83 constitute a computer.

[0052] RAM82 is a volatile semiconductor memory that temporarily holds programs (apps, applications), for example.

[0053] ROM83 is a non-volatile semiconductor memory that can retain programs (apps, applications, etc.) even when the power is turned off. ROM83 stores programs such as the BIOS (Basic Input / Output System) that are executed at startup, as well as various settings such as OS (Operating System) settings and network settings.

[0054] The storage I / F84 is an interface with external storage devices such as storage medium 84a.

[0055] Storage media 84a include, for example, SD (Secure Digital) memory cards, USB (Universal Serial Bus) memory, HDDs (Hard Disk Drives), and SSDs (Solid State Drives).

[0056] The external I / F 85 is an interface that connects the transfer units 31, 32, and 33, which are controlled, to the CPU 81. The external I / F 85 also connects the pressure gauges 51 and 52, which perform measurements, to the CPU 81. Through the external I / F 85, the CPU 81 controls the transfer units 31, 32, and 33. The CPU 81 also acquires measurement results from the pressure gauges 51 and 52 via the external I / F 85.

[0057] Next, the functional configuration of the control unit 80 will be described. Figure 3 is a functional configuration diagram illustrating the functional configuration of the control unit 80 in a gas treatment system 1, which is an example of a gas treatment system according to the first embodiment.

[0058] The control unit 80 comprises a flow rate calculation unit 80A, a target value calculation unit 80B, an operation value calculation unit 80C, and an equipment control unit 80M. The functions of the flow rate calculation unit 80A, the target value calculation unit 80B, the operation value calculation unit 80C, and the equipment control unit 80M are realized by the CPU 81 executing a program.

[0059] (Flow rate calculation part 80A) The flow rate calculation unit 80A calculates the flow rate of the unpermeable gas based on the pressure of the supply gas supplied to the gas separation unit and the pressure of the unpermeable gas discharged in the gas separation unit without passing through the separation membrane. Directly measuring the flow rates of the supply gas and unpermeable gas supplied to the gas separation unit while minimizing energy loss due to pressure loss is difficult. The inventors have found that by calculating the flow rate of the unpermeable gas based on the pressure of the supply gas supplied to the gas separation unit and the pressure of the unpermeable gas discharged in the gas separation unit without passing through the separation membrane, it is possible to measure the flow rate with sufficient accuracy for practical use.

[0060] The processing in the flow rate calculation unit 80A will be explained in detail. The flow rate calculation unit 80A calculates the flow rate Q2, which is the mass flow rate of the unpermeated gas Gn2 discharged from the gas separation unit 20. Based on the pressure P21 of the permeate gas Gp1, which is the gas supplied to the gas separation unit 20, and the pressure P22 of the unpermeated gas Gn2, the flow rate calculation unit 80A calculates the flow rate Q2, which is the mass flow rate of the unpermeated gas Gn2.

[0061] Based on the flow rate measurement method using a throttling mechanism shown in Japanese Industrial Standard JIS Z 8762-2:2007 (Method for measuring flow rate using a throttling mechanism for circular pipes - Part 2: Orifice plate), the inventors derived a method for calculating the flow rate Q2, which is the mass flow rate, in the flow rate calculation unit 80A.

[0062] The flow rate calculation unit 80A calculates the flow rate Q2 (unit: kilograms per second (kg / s)), which is the mass flow rate, using pressure P21 (unit: Pascals (Pa)) and pressure P22 (unit: Pascals (Pa)) based on Equation 1.

[0063]

number

[0064] Kc is the flow rate conversion coefficient (dimensionless), ε is the expansion correction coefficient (dimensionless), and ρ is the density (unit: kilograms per cubic meter (kg / m³)). 3 )) is. S (Unit: square meter (m2 ) is the cross-sectional area corresponding to the cross-sectional area through which the unpermeable gas Gn2 permeates in the gas separation unit 20 (gas passage cross-sectional area). The cross-sectional area S is the cross-sectional area of ​​the aperture hole in the orifice plate (if the aperture hole diameter is d, then πd 2 This corresponds to / 4).

[0065] The flow rate conversion coefficient Kc is calculated using Equation 2.

[0066]

number

[0067] C is the discharge coefficient (dimensionless), and β is the throttling ratio (dimensionless). β is the square root of the ratio of the cross-sectional area S0 of the piping in which the gas separation unit 20 is located to the cross-sectional area S through which the gas passes (β = √(S / S0)).

[0068] The discharge coefficient C represents the ratio of the theoretical value to the actual flow rate. In an orifice, the discharge coefficient C is generally around 0.6. As specified in the Japanese Industrial Standard JIS Z 8762-2, the discharge coefficient C depends on the throttling ratio β, the Reynolds number, and the pipe diameter. Furthermore, the discharge coefficient C varies depending on the method of pressure extraction. The Reynolds number, in turn, depends on the mass flow rate. Therefore, the discharge coefficient C is not a uniquely determined parameter but is determined through iterative calculations.

[0069] The flow rate calculation unit 80A may, for example, calculate the discharge coefficient C in accordance with the method specified in the Japanese Industrial Standard JIS Z 8762-2, or it may determine the discharge coefficient C based on process conditions and experimental values. For example, the flow rate calculation unit 80A may perform a performance test in advance and determine the discharge coefficient C based on the test results.

[0070] The expansion correction coefficient ε is a coefficient used to compensate for the compressibility of a fluid, taking into account its compressibility. For incompressible fluids, such as water, the expansion correction coefficient ε is 1.0. For compressible fluids, the expansion correction coefficient ε is less than 1.

[0071] The expansion correction coefficient ε depends on the throttling ratio β, the primary pressure (pressure P21), the secondary pressure (pressure P22), and the Eisentropic index κ. The Eisentropic index κ represents the ratio of the relative pressure transformations corresponding to the relative change in density in a reversible adiabatic change (isentropic change). For example, the Eisentropic index κ for air may be approximately 1.4.

[0072] In gas processing systems using separation membranes, measuring pressure changes in minute spaces along the length of the separation membrane and volume reduction due to the permeation of the target gas to the permeate side is practically difficult. For example, measuring the pressure drop and volume reduction due to the permeation of carbon dioxide molecules with a size of 0.3 nanometers over a certain section in a real device is not practical and is difficult to measure. Therefore, it is common to model and calculate these parameters by assuming, for example, that the membrane inlet supply pressure is uniformly distributed across the membrane surface.

[0073] On the other hand, if the flow rate calculation is performed by reflecting the pressure changes in each minute space along the length of the separation membrane and the volume reduction due to the permeation of the target gas to the permeate side in the calculation formula, the processing load on the computer becomes enormous. Therefore, although it is possible to perform calculations for small-scale systems at the laboratory level, it is difficult to apply this to flow rate calculations at the level of actual products.

[0074] The gas processing system according to the first embodiment can calculate the flow rate of unpermeated gas in the second gas separation unit with practically sufficient accuracy and minimal calculations, based on the first pressure measured by the first pressure gauge and the second pressure measured by the second pressure gauge. The accuracy of the flow rate calculation by the flow rate calculation unit 80A was found to be an error of approximately 5% to 10%. Considering that the accuracy of the flow meter used to measure the gas is approximately 3% to 5% of the full scale, this accuracy is practically sufficient.

[0075] (Target value calculation unit 80B) The target value calculation unit 80B calculates the target value SV3 for the rotational speed in the transfer unit 33 based on the flow rate Q2, which is the mass flow rate. The target value calculation unit 80B uses the relationship between the discharge flow rate F and the rotational speed n in the transfer unit 33, which is determined based on experiments or predetermined characteristic data, to calculate the target value SV3 for the rotational speed that corresponds to the flow rate Q2, which is the mass flow rate.

[0076] For example, suppose the relationship between the discharge flow rate F and the rotational speed n is given by Equation 3. Here, Kn is a coefficient determined based on experimental or predetermined characteristic data.

[0077] F = n × Kn ··· (Equation 3)

[0078] The target value calculation unit 80B calculates the target value SV3 for rotational speed based on equation 4.

[0079] SV3 = Q2 / Kn (Formula 4)

[0080] (Operational value calculation unit 80C) The operating value calculation unit 80C calculates an operating value MV3 such that the rotation speed of the transfer unit 33 becomes the target value, based on the difference between the measured value PV3, which is the rotation speed of the transfer unit 33 at the current time, and the target value SV3.

[0081] (Equipment Control Unit 80M) The equipment control unit 80M controls the equipment connected to the control unit 80. The equipment control unit 80M acquires measurement results from the pressure gauge 51 and the pressure gauge 52. The equipment control unit 80M also acquires the operating status from the transfer unit 31, the transfer unit 32, and the transfer unit 33. Furthermore, the equipment control unit 80M controls the transfer unit 31, the transfer unit 32, and the transfer unit 33.

[0082] Next, we will describe the specific processing flow in the gas processing system 1. Figure 4 is a flowchart illustrating the processing of the control unit 80 in the gas processing system 1, which is an example of a gas processing system according to the first embodiment.

[0083] (Step S10) First, the control unit 80 acquires the measurement result from the pressure gauge 51. Specifically, the equipment control unit 80M in the control unit 80 controls the pressure gauge 51 to measure the pressure of the permeate gas Gp1, which is the supply gas to the gas separation unit 20. Then, the equipment control unit 80M acquires the pressure P21, which is the result of the measurement from the pressure gauge 51.

[0084] (Step S20) Next, the control unit 80 acquires the measurement result from the pressure gauge 52. Specifically, the equipment control unit 80M in the control unit 80 controls the pressure gauge 52 to measure the pressure of the unpermeated gas Gn2 in the gas separation unit 20. Then, the equipment control unit 80M acquires the pressure P22, which is the result measured from the pressure gauge 52.

[0085] (Step S30) Next, the control unit 80 calculates the flow rate Q2 of the unpermeated gas Gn2 in the gas separation unit 20 based on pressures P21 and P22. Specifically, the flow rate calculation unit 80A in the control unit 80 obtains pressures P21 and P22 from the equipment control unit 80M. Then, the flow rate calculation unit 80A calculates the flow rate Q2 from the pressure difference between pressures P21 and P22.

[0086] (Step S40) Next, the control unit 80 calculates a target value SV3 in the transfer unit 33 based on the flow rate Q2. Specifically, the target value calculation unit 80B in the control unit 80 obtains the flow rate Q2 from the flow rate calculation unit 80A. Then, the target value calculation unit 80B calculates a target value SV3, which is the rotational speed in the transfer unit 33, from the flow rate Q2. For example, the target value calculation unit 80B calculates the target value SV3 (unit: per second ( / s)), which is the rotational speed, based on the following equation 5.

[0087] SV3 = Q2 / Kr (Formula 5)

[0088] However, Kr (unit: kilograms (kg)) is a constant that converts rotational speed to mass flow rate.

[0089] (Step S50) Next, the control unit 80 calculates an operational value MV3 that eliminates the deviation between the target value SV3 and the current measured value PV3 in the transfer unit 33. Specifically, the operational value calculation unit 80C in the control unit 80 obtains the target value SV3 from the target value calculation unit 80B. The operational value calculation unit 80C also obtains the current measured value PV3 of the rotational speed in the transfer unit 33 from the equipment control unit 80M. Then, the operational value calculation unit 80C calculates the operational value MV3 to eliminate the deviation between the target value SV3 and the measured value PV3.

[0090] (Step S60) Next, the control unit 80 controls the transfer unit 33 based on the operation value MV3. Specifically, the equipment control unit 80M in the control unit 80 controls the transfer unit 33 based on the operation value MV3 calculated by the operation value calculation unit 80C.

[0091] (Step S70) Next, the control unit 80 determines whether the deviation between the target value SV3 and the measured value PV3 is less than or equal to a threshold. If the deviation between the target value SV3 and the measured value PV3 is less than or equal to the threshold, the control unit 80 terminates the process. If the deviation between the target value SV3 and the measured value PV3 is greater than the threshold, the control unit 80 returns to step S10 and repeats the process.

[0092] To combat global warming and reduce carbon dioxide emissions, the International Maritime Organization (IMO) introduced the Energy Efficiency Design Index (EEDI) regulation as a performance requirement for ships. The EEDI indicates the amount of carbon dioxide emissions per unit of transport. Under the EEDI regulation, a 30% reduction in carbon dioxide emissions is required in Phase 3, starting from 2025, compared to Phase 0, which was introduced in 2013.

[0093] In response to the situation described above, various efforts are being made to reduce carbon dioxide emissions from engine exhaust gases, which are the power source of ships. One of these efforts is carbon dioxide capture on board ships.

[0094] To reduce carbon dioxide emissions, it is crucial to achieve a high carbon dioxide capture rate. At the same time, in carbon dioxide capture systems on ships, space constraints necessitate removing gases other than carbon dioxide, separating carbon dioxide to a higher concentration, and compactly storing the captured carbon dioxide.

[0095] For example, existing technologies such as chemical absorption require excessive equipment, so there is a demand for carbon dioxide recovery using separation membranes that can save space.

[0096] In carbon dioxide capture systems using separation membranes, it is possible to increase the concentration of captured carbon dioxide by arranging the separation membranes in series in multiple stages. Furthermore, in multi-stage carbon dioxide capture systems, a recycling process is being considered in which the unpermeated gas from the downstream separation membrane, which has a higher carbon dioxide concentration, is mixed with the supply gas from the upstream separation membrane as a recycled gas, with the aim of increasing the carbon dioxide recovery rate.

[0097] For a gas separation membrane to perform optimally, a pressure difference must be maintained between the supply and permeate sides of the membrane as a driving force. Possible means of generating this pressure difference include pumping gas from the supply side or reducing pressure from the permeate side. For reducing system power consumption, pressure reduction is preferable. Furthermore, since the discharge pressure of a pressure reducing pump or blower is equivalent to atmospheric pressure, if a recycling process is applied to the unpermeated side of the separation membrane, a means of adding pressure for gas mixing, such as a recycling pump or blower, is necessary.

[0098] When using a recycle pump or blower, it is necessary to control the output of the recycle pump or blower in accordance with the flow rate of the unpermeated gas through the separation membrane (synchronized with the flow rate of the non-permeated flow). In general, measuring the flow rate of gas is difficult, especially as the diameter increases. For example, when measuring the flow rate by differential pressure using an orifice, the energy loss due to pressure drop in the orifice becomes significant.

[0099] The gas separation apparatus according to the first embodiment calculates the flow rate of the second unpermeated gas from the output of the third transfer unit installed in the recycling line, the first pressure of the first permeated gas supplied to the second gas separation unit, and the second pressure of the second unpermeated gas discharged from the gas separation unit. The gas separation apparatus according to the first embodiment then controls the third transfer unit according to the calculated flow rate of the second unpermeated gas.

[0100] As described above, the gas treatment system according to the first embodiment calculates the flow rate of the second unpermeated gas based on the pressures on the suction and discharge sides of the second gas separation unit, without directly measuring the flow rate of the second unpermeated gas. By calculating the flow rate of the second unpermeated gas based on the pressures on the suction and discharge sides of the second gas separation unit, the gas treatment system according to the first embodiment can control the flow rate in the third transfer section with a simple configuration.

[0101] <Second Embodiment> The gas treatment system according to the second embodiment further includes a third pressure gauge, a fourth pressure gauge, and a control valve in addition to the gas treatment system according to the first embodiment. The third pressure gauge in the gas treatment system according to the second embodiment measures the third pressure, which is the pressure of the raw material gas, in the raw material gas line. The fourth pressure gauge in the gas treatment system according to the second embodiment measures the fourth pressure, which is the pressure of the second unpermeated gas, downstream of the third transfer section in the recycling line. The control valve in the gas treatment system according to the second embodiment is provided downstream of the third transfer section in the recycling line and upstream of the fourth pressure gauge. The control unit in the gas treatment system according to the second embodiment controls the control valve provided in the recycling line based on the third pressure of the raw material gas and the fourth pressure of the recycled gas, in addition to the processing performed by the control unit in the gas treatment system according to the first embodiment.

[0102] The configuration of the gas treatment system according to the second embodiment will now be described. Figure 5 is a diagram illustrating the schematic configuration of gas treatment system 2, which is an example of a gas treatment system according to the second embodiment.

[0103] Gas processing system 2 includes, in addition to the configuration of gas processing system 1, pressure gauges 53 and 54, and a control valve 91. Furthermore, gas processing system 2 replaces the control unit 80 in gas processing system 1 with a control unit 180. Regarding the configuration of gas processing system 2 that is common to gas processing system 1, please refer to the description of gas processing system 1, and the explanation will be omitted here.

[0104] (Pressure gauge 53 and pressure gauge 54) The pressure gauge 53 is installed in the raw material gas line 61. The pressure gauge 53 measures the pressure of the raw material gas Gm supplied to the gas separation unit 10.

[0105] The pressure gauge 54 is installed downstream of the control valve 91 in the recycling line 65. The pressure gauge 54 measures the pressure of the recycled gas Gr.

[0106] (Control valve 91) The control valve 91 controls the flow rate and pressure of the recycled gas Gr flowing through the recycling line 65. The control valve 91 is controlled by the control unit 180.

[0107] (Control unit 180) The control unit 180 controls the gas processing system 2. Specifically, the control unit 180 controls the transfer unit 31, the transfer unit 32, and the transfer unit 33, respectively. The control unit 180 also acquires the pressure detection results from the pressure gauges 51, 52, 53, and 54, respectively. Furthermore, the control unit 180 controls the control valve 91.

[0108] In the gas processing system 2, the control unit 180 controls the transfer unit 33 based on the flow rate of the unpermeable gas Gn2 discharged from the gas separation unit 20, similar to the control unit 80. In addition, in the gas processing system 2, the control unit 180 controls the control valve 91 so that the pressure of the recycled gas Gr that joins the raw material gas Gm is within an appropriate range.

[0109] Since the hardware configuration of the control unit 180 is the same as that of the control unit 80, please refer to the description of the control unit 80, and the explanation will be omitted here.

[0110] Next, the functional configuration of the control unit 180 will be described. Figure 6 is a functional configuration diagram illustrating the functional configuration of the control unit 180 in a gas treatment system 2, which is an example of a gas treatment system according to the second embodiment.

[0111] The control unit 180 includes a flow rate calculation unit 80A, a target value calculation unit 80B, an operation value calculation unit 80C, an operation value calculation unit 180D, and an equipment control unit 180M. The functions of the flow rate calculation unit 80A, the target value calculation unit 80B, the operation value calculation unit 80C, the operation value calculation unit 180D, and the equipment control unit 180M are realized by executing a program in the CPU 81 shown in Figure 2.

[0112] The flow rate calculation unit 80A, the target value calculation unit 80B, and the operation value calculation unit 80C are described in the gas treatment system 1, and their explanations are omitted here.

[0113] (Operational value calculation unit 180D) The operating value calculation unit 180D calculates an operating value MV4, which is an operating value related to the opening degree of the control valve 91, so that the pressure P3 in the recycling line 65 becomes a predetermined pressure with respect to the pressure P0 of the raw material gas Gm.

[0114] For example, the operating value calculation unit 180D uses equation 6 to determine the desired target pressure P3t (in Pascals (Pa)) based on the pressure P0 (in Pascals (Pa)). Then, the operating value calculation unit 180D calculates the operating value MV4 related to the opening degree of the control valve 91 so that the pressure P3 (in Pascals (Pa)) becomes the target pressure P3t (in Pascals (Pa)).

[0115] P3t = P0 × (1+α) (Equation 6)

[0116] However, α is the design margin. The design margin α is set appropriately between 0.03 and 0.05. For example, the design margin α is 0.05. Note that the specific value of the design margin α may be determined empirically and arbitrarily based on actual values, for example.

[0117] (Equipment Control Unit 180M) The equipment control unit 180M controls the equipment connected to the control unit 180. The equipment control unit 80M acquires measurement results from pressure gauges 51, 52, 53, and 54. The equipment control unit 180M also acquires the operating status from each of the transfer units 31, 32, and 33. Furthermore, the equipment control unit 180M controls each of the transfer units 31, 32, and 33. The equipment control unit 180M also controls the control valve 91.

[0118] Next, we will describe the specific processing flow in the gas processing system 2. Figure 7 is a flowchart illustrating the processing of the control unit 180 in the gas processing system 2, which is an example of a gas processing system according to the second embodiment.

[0119] For processes common to gas treatment system 1, please refer to the description of gas treatment system 1, and the explanation will be omitted here.

[0120] (Step S141) The control unit 180 calculates the static pressure h in the transfer unit 33 when it is operated according to the target value SV3. Specifically, the operation value calculation unit 180D in the control unit 180 obtains the target value SV3 from the target value calculation unit 80B. Then, for example, if the target value SV3 is the rotational speed, the operation value calculation unit 180D calculates the static pressure h (unit: Pascals (Pa)) using the target value SV3 (unit: per second ( / s)) based on, for example, Equation 7.

[0121] h = SV3 2 × Kp (Formula 7)

[0122] However, Kr (unit: kilograms per meter (kg / m)) is a constant that converts the square of the rotational speed into pressure.

[0123] (Step S142) Next, the control unit 180 calculates the target pressure P3t. Specifically, the operating value calculation unit 180D in the control unit 180 obtains the pressure P0 from the equipment control unit 180M. Then, the operating value calculation unit 180D calculates the target pressure P3t based on equation 6.

[0124] (Step S143) Next, the control unit 180 determines whether the difference between the target pressure P3T and pressure P21 is equal to the static pressure h calculated in step S141. If the difference between the target pressure P3T and pressure P21 is equal to the static pressure h calculated in step S141 (YES in step S142), the control unit 180 proceeds to step S50. If the difference between the target pressure P3T and pressure P21 is not equal to the static pressure h calculated in step S141 (NO in step S142), the control unit 180 proceeds to step S144.

[0125] (Step S144) If the difference between the target pressure P3T and pressure P21 is not equal to the static pressure h calculated in step S141 (NO in step S142), the control unit 180 controls the control valve 91 so that pressure P3 becomes the target pressure P3t.

[0126] When using a recycling pump or blower in a recycling line, if the pressure of the recycled gas is too high, the recycled gas may flow back into the raw material gas line, preventing the raw material gas from being supplied to the gas separation unit. Therefore, it is necessary to control the pressure of the recycled gas.

[0127] The gas treatment system according to the second embodiment, in addition to the operation and effects of the gas treatment system according to the first embodiment, controls the pressure of the recycled gas based on the third pressure of the raw material gas and the fourth pressure of the recycled gas, thereby enabling control of the recycled gas pressure with a simple configuration.

[0128] <Third Embodiment> A gas treatment system according to the third embodiment will now be described. The gas treatment system according to the third embodiment is equipped with a pressure gauge, flow meter, control valve, and transfer unit added to the gas treatment system according to the second embodiment.

[0129] The gas treatment system according to the third embodiment will be described in detail with reference to the drawings. Figure 8 is a diagram illustrating the schematic configuration of gas treatment system 3, which is an example of the gas treatment system according to the third embodiment.

[0130] Gas treatment system 3 includes pressure gauges 55 and 56 in addition to those of gas treatment system 2. Gas treatment system 3 also includes a flow meter 58. Furthermore, gas treatment system 3 includes a control valve 92. Additionally, gas treatment system 3 includes a transfer unit 34. Furthermore, gas treatment system 3 includes a control unit 280 instead of the control unit 180. For configurations in gas treatment system 3 that are common to gas treatment system 1 or gas treatment system 2, please refer to the description of gas treatment system 1 or gas treatment system 2; detailed explanations are omitted here.

[0131] (Pressure gauge 55 and pressure gauge 56) The pressure gauge 55 is installed between the gas mixing header 70 and the gas separation unit 10 in the raw gas line 61. The pressure gauge 55 measures the pressure of the mixed gas Gc, which is a mixture of raw gas Gm and recycled gas Gr, supplied to the gas separation unit 10. In other words, the pressure gauge 55 measures the pressure of the mixed gas Gc, which is the gas supplied to the gas separation unit 10.

[0132] The pressure gauge 56 is installed in the exhaust gas line 63. The pressure gauge 56 measures the pressure of the unpermeated gas Gn1.

[0133] (Flowmeter 58) The flow meter 58 is installed in the gas recovery line 64. The flow meter 58 measures the flow rate of the permeate gas Gp2 flowing through the gas recovery line 64.

[0134] The flow meter 58 is not limited in type as long as it can measure the flow rate of the permeate gas Gp2. For example, the flow meter 58 may be a differential pressure flow meter or a vortex flow meter. Alternatively, a flow velocity meter may be used to convert the flow rate into a flow meter.

[0135] (Control valve 92) The control valve 92 controls the flow rate of impermeable gas Gn1 flowing through the exhaust gas line 63. The control valve 92 is controlled by the control unit 280.

[0136] The control unit 280 controls the gas processing system 3. Specifically, the control unit 280 controls the transfer units 31, 32, 33, and 34. The control unit 280 also acquires the pressure detection results from the pressure gauges 51, 52, 53, 54, 55, and 56. Furthermore, the control unit 280 acquires the flow rate detection results from the flow meter 58. The control unit 280 also controls the control valves 91 and 92.

[0137] The processing of the control unit 280 will now be described. For example, if the flow rate and pressure of the raw material gas Gm fluctuate due to load fluctuations at the raw material gas Gm supply source, the control unit 280 may adjust the output of the transfer unit 34 in accordance with the load fluctuations at the raw material gas Gm supply source.

[0138] Furthermore, the control unit 280 may adjust the control valve 92 so that the supply pressure in the gas separation unit 10 becomes a predetermined set pressure. For example, if the raw material gas Gm decreases due to load fluctuations, the control unit 280 may control the opening of the control valve 92 to narrow so that the supply pressure in the gas separation unit 10 becomes a predetermined pressure. Note that the exhaust speed of the transfer unit 31 and the transfer unit 32 differs depending on the capacity of the suction side, but adjustments due to fluctuations in the inflow rate due to load fluctuations are not required.

[0139] The control unit 280 may increase or decrease the output of the transfer unit 34 if the recovered gas Ge does not match a predetermined recovery rate, in other words, if the flow rate measured by the flow meter 58 does not match a desired flow rate. The control unit 280 may also control the transfer unit 34 based on the flow rate measured by the flow meter 58.

[0140] The gas treatment system 3 is equipped with a flow meter 58 only in the gas recovery line 64. Since the diameter of the gas recovery line 64 is generally small, it is relatively easy to measure the gas flow rate.

[0141] The flow rate of permeate gas Gp2 in the gas separation unit 20 can be measured by the flow meter 58. As described above, the flow rate of unpermeated gas Gn2 in the gas separation unit 20 can be calculated using the measurement results of pressure gauge 51 and pressure gauge 52, respectively. Therefore, the flow rate of permeate gas Gp1, which is the supply gas supplied to the gas separation unit 20, can be calculated by the sum of the flow rate of permeate gas Gp2 and the flow rate of unpermeated gas Gn2 in the gas separation unit 20.

[0142] Furthermore, in the gas processing system 3, the flow rate of unpermeated gas Gn1 in the gas separation unit 10 can be calculated from the pressures measured by pressure gauges 55 and 56, respectively, as calculated in the gas separation unit 20 in the gas processing system 1. Therefore, the flow rate of mixed gas Gc, which is the supply gas supplied to the gas separation unit 10, can be calculated based on the flow rate of permeated gas Gp1 and the flow rate of unpermeated gas Gn1 calculated from the flow rate in the gas separation unit 20 as described above. In other words, the flow rate of mixed gas Gc can be calculated from the sum of the flow rate of permeated gas Gp1 and the flow rate of unpermeated gas Gn1.

[0143] Furthermore, since the flow rate of the recycled gas Gr can be calculated from the unpermeated gas Gn2, the flow rate of the raw material gas Gm can be calculated from the flow rate of the mixed gas Gc and the flow rate of the recycled gas Gr. In other words, the flow rate of the raw material gas Gm can be calculated by subtracting the flow rate of the recycled gas Gr from the flow rate of the mixed gas. The control unit 280 may control the output of the transfer unit 34 using the calculated flow rate of the raw material gas Gm. Note that the flow rate of the raw material gas Gm may also be calculated, for example, from the load of an engine or other device that discharges the raw material gas Gm.

[0144] As described above, in the gas treatment system according to the third embodiment, if a flow meter is installed in the recovery line, the gas flow rate in each line can be calculated without installing flow meters in lines other than the recovery line.

[0145] Note that the transfer unit 34 is an example of the fourth transfer unit, the pressure gauge 55 is an example of the fifth pressure gauge, and the pressure gauge 56 is an example of the sixth pressure gauge.

[0146] In the embodiment described above, the gas separation apparatus comprises two gas separation units, but the number of gas separation units is not limited to two. The gas separation apparatus of this disclosure may comprise three or more gas separation units.

[0147] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of Symbols]

[0148] 1, 2, 3 Gas Processing Systems 10, 20 Gas Separation Units 10S1, 20S1 Non-transparent side space 10S2, 20S2 Transmission side space 11, 21 Separation membrane 31, 32, 33, 34 Transfer section 51, 52, 53, 54, 55, 56 Pressure gauge 58 Flow meter 61. Raw material gas line 62 connection lines 63 Exhaust gas line 64 Gas recovery line 65 Recycling Line 70 Gas Mixing Header 80, 180 Control Unit 80A flow rate calculation section 80B Target Value Calculation Unit 80C, 180D Operating Value Calculation Unit 80M, 180M Equipment Control Unit 84a Storage medium 91, 92 Control valves 280 Control Unit Gc mixed gas G-recovered gas Gm raw material gas Gn1, Gn2 Unpermeable Gas Gp1, Gp2 permeable gas Gr Recycled Gas P0, P3, P21, P22 pressure P3t Target Pressure MV3, MV4 control values PV3 measurement value SV3 Target Value Q2 Flow rate

Claims

1. A first gas separation unit comprising a first separation membrane, to which a raw material gas is supplied, and to which the supplied raw material gas is separated into a first permeate gas that permeates through the first separation membrane and a first unpermeate gas that is discharged without permeating through the first separation membrane, A second gas separation unit is connected in series with the first gas separation unit, and is equipped with a second separation membrane, to which the first permeate gas is supplied, and which separates the supplied first permeate gas into a second permeate gas that permeates through the second separation membrane and a second unpermeated gas that is discharged without permeating through the second separation membrane, A raw material gas line that supplies the raw material gas to the first gas separation unit, A recycling line that returns the second unpermeated gas to the raw material gas line, A first transfer unit that supplies the first permeate gas in the first gas separation unit to the second gas separation unit, The second gas separation unit includes a second transfer unit that discharges the second permeate gas to the outside, A third transfer unit is located in the recycling line and sends the second unpermeated gas to the raw material gas line, A first pressure gauge for measuring the pressure of the first permeate gas supplied to the second gas separation unit, A second pressure gauge for measuring the pressure of the second unpermeable gas discharged from the second gas separation unit, In the aforementioned raw material gas line, a third pressure gauge is provided for measuring the pressure of the raw material gas, A fourth pressure gauge for measuring the pressure of the second unpermeated gas is provided downstream of the third transfer section in the recycling line. A control valve is provided downstream of the third transfer section in the recycling line and upstream of the fourth pressure gauge, A control unit controls the third transfer unit based on the first pressure measured by the first pressure gauge and the second pressure measured by the second pressure gauge, and controls the control valve based on the third pressure measured by the third pressure gauge and the fourth pressure measured by the fourth pressure gauge. Equipped with, Gas processing system.

2. The control unit calculates the flow rate of the second unpermeated gas based on the pressure difference between the first pressure and the second pressure. The gas treatment system according to claim 1.

3. The control unit controls the rotation speed of the third transfer unit so that the flow rate of the second unpermeated gas transferred by the third transfer unit becomes the calculated flow rate. The gas treatment system according to claim 2.

4. The control unit controls the control valve so that the fourth pressure becomes a desired pressure relative to the static pressure of the third transfer unit calculated from the rotational speed. The gas processing system according to claim 3.

5. The system includes a flow meter for measuring the flow rate of the second permeate gas, A gas treatment system according to any one of claims 1 to 4.

6. The system includes a fourth transfer unit that supplies the raw material gas to the raw material gas line, The control unit controls the fourth transfer unit based on the flow rate measured by the flow meter. The gas treatment system according to claim 5.

7. The raw material gas line includes a mixing header that mixes the raw material gas and the second unpermeated gas from the recycling line and supplies the resulting mixed gas to the first gas separation unit, A fifth pressure gauge for measuring the pressure of the mixed gas supplied to the first gas separation unit, The system includes a sixth pressure gauge for measuring the pressure of the first unpermeable gas discharged from the first gas separation unit, The control unit calculates the flow rate of the raw material gas based on the flow rate measured by the flow meter and the pressures measured by the first pressure gauge, the second pressure gauge, the fifth pressure gauge, and the sixth pressure gauge, respectively. The gas treatment system according to claim 5.

8. The system includes a fourth transfer unit that supplies the raw material gas to the raw material gas line, The control unit controls the fourth transfer unit based on the calculated flow rate of the raw material gas. The gas treatment system according to claim 7.

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