Gas separation system

Abstract

To provide a gas separation system that can specify a deteriorated separation membrane when having a plurality of separation membranes by minimizing extension of devices for diagnosing deterioration of the separation membrane.SOLUTION: The present invention is applied to a system for evaluating performance of a separation membrane 12 using a control valve 21 for controlling flow rate of gas separated by the separation membrane 12 for separating gas of a specific component from mixed gas and a pressure gauge 31 for measuring pressure between the separation membrane 12 and the control valve 21. The gas separation system includes: a pressure time change rate calculation section 45 for calculating a pressure time change rate in a prefixed valve opening state using valve opening of the control valve 21 and time series data of a measured value of the pressure gauge 31; and a separation membrane performance evaluation section 46 that evaluates performance of the separation membrane 12 by comparing the pressure time change rate calculated by the pressure time change rate calculation section 45 with an initial value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas separation system. [Background technology]

[0002] One method for separating a specific gas from a mixture of multiple gases is to use a separation membrane that selectively allows gases to permeate. Separation membranes include, for example, molecular sieve membranes, such as ceramic membranes, which separate gases based on differences in molecular diameter, and polymer membranes that utilize differences in the solubility of gases in the membrane. These separation membranes also allow a certain amount of gases to permeate in addition to the specific gas you want to allow to pass through. The side before permeation through the separation membrane is called the primary side, and the side after permeation is called the secondary side.

[0003] The amount of gas permeation through a separation membrane is proportional to the difference between the gas partial pressure on the primary side and the gas partial pressure on the secondary side multiplied by the membrane area. Furthermore, the amount of gas permeation through a separation membrane decreases as the separation membrane deteriorates. In gas separation systems, to maintain separation efficiency, it is necessary to diagnose the deterioration state of the separation membrane and, if the separation membrane deteriorates, to carry out maintenance such as replacing the separation membrane.

[0004] One example of a method for diagnosing deterioration of separation membranes is the technology described in Patent Document 1. Patent Document 1 describes a technology that detects pressure changes in the downstream path of the product gas and determines when to replace the separation membrane based on the pressure change after the equipment is shut down. When the equipment is shut down, the inlet valve on the upstream side of the separation membrane and the outlet valve on the downstream side close, so the technology described in Patent Document 1 reduces the pressure between these valves and determines when to replace them based on this change. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-102717 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a specific gas other than natural gas is mixed with natural gas and transported using an existing gas grid containing methane as the main component, the concentration of the specific gas cannot be controlled properly, and if gas with a concentration outside the allowable range is supplied to equipment, the equipment may break down. In such cases, serious accidents may occur in production facilities, chemical plants, and other facilities, so deterioration diagnosis of gas separation systems must be carried out periodically.

[0007] Therefore, it is necessary to achieve high-precision deterioration diagnosis of gas separation systems. However, because deterioration diagnosis of separation membranes requires multiple measurements such as concentration and flow rate, it requires multiple sensors such as gas concentration meters and flow meters, which results in high costs. Furthermore, when multiple separation membranes are used, only an overall evaluation can be performed, making it impossible to identify the deteriorated separation membrane.

[0008] An object of the present invention is to provide a gas separation system that minimizes the need for additional equipment for diagnosing deterioration of separation membranes and that can identify a deteriorated separation membrane when multiple separation membranes are used. [Means for solving the problem]

[0009] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above-mentioned problems, and one example thereof is a gas separation system that is applied to a system for evaluating the performance of a separation membrane using a control valve that controls the flow rate of gas separated by a separation membrane that separates a gas of a specific component from a mixed gas, and a pressure gauge that measures the pressure between the separation membrane and the control valve. The gas separation system is configured to include a pressure time change rate calculation unit that calculates the pressure time change rate at a predetermined valve opening state using the valve opening of the control valve and time series data of the measurement value of the pressure gauge, and a separation membrane performance evaluation unit that compares the pressure time change rate calculated by the pressure time change rate calculation unit with an initial value to evaluate the performance of the separation membrane. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce the need for additional equipment for diagnosing the deterioration of separation membranes and to appropriately evaluate the performance of separation membranes. For example, when a plurality of separation membranes are used, it is possible to identify a deteriorated separation membrane. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram showing an example of a gas separation system according to a first embodiment of the present invention. [Figure 2] FIG. 3 is a diagram showing the flow of signals in the control device of the gas separation system according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of time-series data of pressure measurement values ​​of the gas separation system according to the first embodiment of the present invention. [Figure 4] 4 is a flowchart showing an example of processing by a separation membrane performance evaluation unit of the gas separation system according to the first embodiment of the present invention. [Figure 5] 1 is a configuration diagram showing an example of a gas separation system according to a first embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing an example of time-series data of pressure measurement values ​​of the gas separation system according to the second embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing an example (example 1) of a display screen of the gas separation system according to the second embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing an example (example 2) of a display screen of the gas separation system according to the second embodiment of the present invention. [Figure 9] FIG. 10 is a configuration diagram showing an example of a gas separation system according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a configuration diagram showing an example of a gas separation system according to a fourth embodiment of the present invention. [Figure 11] FIG. 10 is a configuration diagram showing an example of a gas separation system according to a fifth embodiment of the present invention. [Figure 12]FIG. 10 is a diagram showing the flow of signals in the control device of the gas separation system according to the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] <First embodiment> A gas separation system according to a first embodiment of the present invention will now be described with reference to FIGS.

[0013] [Gas separation system configuration] 1 shows an example of the configuration of a gas separation system 1 according to this embodiment. In this embodiment, a mixture of hydrogen and methane is used as the supply gas, and hydrogen is separated from this mixture gas by a separation membrane. In such a case, the gas separation system 1 of this embodiment controls the hydrogen concentration of the extracted gas to a predetermined value even if the hydrogen concentration of the supply gas fluctuates around a certain value. For example, the gas separation system 1 controls the hydrogen concentration to a constant value such as 20% (vol%), to a value above or below a predetermined value, or within a predetermined range.

[0014] In the example shown in Fig. 1, gas separation system 1 is configured to receive a supply of a mixed gas of hydrogen and methane through mixed gas supply piping 2. Gas separation system 1 has a gas separation membrane module 11. Separation membrane module 11 is separated into a primary side 13 and a secondary side 14 by a separation membrane 12. The primary side is the side where gas does not permeate the separation membrane, and the secondary side is the side where gas has permeated the separation membrane.

[0015] The mixed gas supply pipe 2 is connected to the primary side 13. A non-permeate gas pipe 3 is connected to the primary side 13. A permeate gas pipe 4 is connected to the secondary side 14. Of the mixed gas supplied from the mixed gas supply pipe 2 to the primary side 13, mainly hydrogen permeates the separation membrane 12. Methane also permeates the separation membrane 12, but hydrogen permeates more easily than methane. For this reason, the hydrogen concentration is higher on the secondary side 14 than on the primary side 13. The amount of permeation of each gas is proportional to the partial pressure difference between the primary side 13 and the secondary side 14.

[0016] The permeate gas pipe 4 is provided with a control valve 21. The control valve 21 receives commands from a valve opening command unit 42 of the control device 41 and adjusts the valve opening. Typically, the valve opening of the control valve 21 is calculated by the control device 41 so as to control the pressure, flow rate, or concentration of the permeate gas. In addition, a pressure gauge 31 is provided between the control valve 21 and the secondary side 14. The pressure gauge 31 measures the permeate gas pressure and transmits the pressure measurement value to a measurement value input unit 43 of the control device 41.

[0017] The control device 41 is composed of a valve opening command unit 42, a measurement value input unit 43, a database 44, a pressure time rate of change calculation unit 45, and a separation membrane performance evaluation unit 46. The processing performed by these components will be explained with reference to FIG. The results of evaluation by the separation membrane performance evaluation unit 46 of the control device 41 are sent to the terminal 47 and displayed on the display unit of the terminal 47. In addition, the valve opening command unit 42 sets the valve opening based on the command sent from the terminal 47.

[0018] The control device 41 can be configured by, for example, a computer. The hardware configuration of the control device 41 is shown in the lower right of FIG. The computer that functions as the control device 41 is configured with a CPU (Central Processing Unit) 41a, a memory 41b, a storage 41c, an input unit 41d, an output unit 41e, and a communication interface 41f.

[0019] The CPU 41a executes programs stored in the memory 41b or the storage 41c. The memory 41b is configured as, for example, a RAM (Random Access Memory), and stores computer programs and calculation result data, and also provides the CPU 41a with a work area required for each process.

[0020] In this embodiment, the CPU 41a executes a program, and a valve opening command unit 42, a measurement value input unit 43, a pressure time rate of change calculation unit 45, and a separation membrane performance evaluation unit 46 are configured in a work area in the memory 41b. The storage 41c stores computer programs, data required for calculations, calculation result data, etc. The storage 41c stores data as a database 44, for example.

[0021] The input unit 41d performs input processing necessary for control. For example, measured values ​​from the pressure gauge 31 and the like are input to the input unit 41d. The output unit 41e performs output processing required for control. For example, the output unit 41e outputs the valve opening command value from the valve opening command unit . The communication interface 41f performs communication processing with other devices via the connected network.

[0022] Note that configuring the control device 41 using a computer is just one example, and for example, part or all of the processing may be configured using hardware such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). 1 is also configured by a computer with the same hardware configuration as the control device 41. Alternatively, the control device 41 may have the functions and configuration of the terminal 47 built in.

[0023] [Control device signal flow] FIG. 2 is a diagram showing the flow of signals in the control device 41 of the gas separation system 1 of this embodiment. Valve opening command unit 42 receives a command to perform performance evaluation from terminal 47 and transmits a command to adjust valve 21 to set the valve opening to zero (step S14). When the pressure on the primary side of the separation membrane is higher than the secondary side and gas is permeating the separation membrane, an administrator may operate terminal 47 to issue a command to perform performance evaluation. Furthermore, the start-up process, shutdown process, and load change process of gas separation system 1 may be integrated into a single process.

[0024] The measurement value input unit 43 receives the measurement value of the pressure gauge 31 and transmits it to the database 44 (step S12). The database 44 stores a predetermined initial value of the pressure time rate of change, upper and lower limits of the difference between the measured value and the initial value, and also stores time-series data of the pressure measurement value. The pressure time rate of change calculation unit 45 receives, from the database 44, time series data of pressure measurement values ​​from the time when a command to set the valve opening to zero is sent to the control valve 21 until the time when a certain period of time has elapsed (step S13). Then, the pressure time rate of change calculation unit 45 calculates the pressure time rate of change K and sends the calculated pressure time rate of change K to the separation membrane performance evaluation unit 46 (step S15).

[0025] 3 is a diagram showing an example of pressure measurement time-series data handled by the gas separation system 1 of this embodiment. The vertical axis of Fig. 3 represents pressure, and the horizontal axis represents time. Data d0 shown in Fig. 3 is an initial value, and data d1 is a measurement value. The pressure measured by the pressure gauge 31 is a certain constant value, but when the valve opening of the control valve 21 becomes zero, the amount of gas permeated accumulates without being discharged from the secondary side, and the pressure of the permeated gas on the secondary side of the separation membrane rises and approaches the pressure on the primary side.

[0026] The pressure time change rate K can be calculated by a known method. For example, as shown in Fig. 3, it can be calculated by dividing the difference between the pressure P(t1) at time t1 when a command to set the valve opening to zero is sent to the regulator valve 21 and the pressure P(t1+Δt) at time (t1+Δt) after a certain period has elapsed by the certain period Δt. Alternatively, the time from the pressure P(t1) at time t1 to the time when the pressure reaches P(t1)+ΔP can be measured, and the pressure time change rate K can be calculated using the following formula: [Number 1] K=(P(t1+Δt)―P(t1)) / Δt

[0027] 2, the separation membrane performance evaluation unit 46 acquires the initial value K0 of the pressure time rate of change, and the upper limit ΔKH and lower limit ΔKL of the difference from the initial value from the database 44 (step S11). Then, the separation membrane performance evaluation unit 46 evaluates the performance of the separation membrane using the acquired pressure time rate of change K, the initial value K0 of the pressure time rate of change, and the upper limit ΔKH and lower limit ΔKL of the difference from the initial value, and transmits the performance evaluation results to the terminal 47 (step S16).

[0028] [Processing performed by the Separation Membrane Performance Evaluation Department] FIG. 4 is a flowchart showing an example of processing by the separation membrane performance evaluation unit 46 of the control device 41 of the gas separation system 1 of this embodiment. First, the separation membrane performance evaluation unit 46 calculates the difference ΔK between the pressure time change rate K calculated by the pressure time change rate calculation unit 45 and the initial value K0 of the pressure time change rate (step S1). Next, the separation membrane performance evaluation unit 46 compares the difference ΔK with a lower limit value ΔKL (step S2). If the comparison in step S2 shows that the difference ΔK is smaller than the lower limit value ΔKL (ΔK<ΔKL) (YES in step S2), the separation membrane performance evaluation unit 46 determines that the separation membrane 12 has deteriorated, and transmits the result to the terminal 47 (step S3).

[0029] On the other hand, if the difference ΔK is not smaller than the lower limit value ΔKL (ΔK≧ΔKL) in the comparison in step S2 (NO in step S2), the separation membrane performance evaluation unit 46 proceeds to the next process and compares the difference ΔK with the upper limit value ΔKH (step S4). In the comparison in step S4, if the difference ΔK is greater than the upper limit value ΔKH (ΔK>ΔKH) (YES in step S4), the separation membrane performance evaluation unit 46 determines that an abnormality has occurred and transmits the result to the terminal 47 (step S5). On the other hand, if the difference ΔK is not greater than the upper limit value ΔKH (ΔK≦ΔKH) in the comparison in step S4 (NO in step S4), the separation membrane performance evaluation unit 46 transmits the value (ΔK / ΔKL) obtained by dividing the difference ΔK by the lower limit value ΔKL to the terminal 47 (step S6).

[0030] [Effects of the first embodiment] In gas separation system 1, when separation membrane 12 deteriorates, the amount of gas permeating through the separation membrane decreases even when the partial pressure difference between the gases on primary side 13 and secondary side 14 is the same. When the amount of gas permeating through the separation membrane decreases, the rate of pressure increase slows after control valve 21 reaches zero. That is, as shown in FIG. 3, compared to the initial value d0 of the pressure increase through the separation membrane, the measured value d1 after a certain amount of gas permeation has occurred shows a slower rate of pressure increase, and the degree to which this rate of increase slows increases in response to the deterioration of separation membrane 12.

[0031] Here, the gas separation system 1 of this embodiment detects a deterioration in the performance of the separation membrane 12 from such a change in the rate of pressure change, and if the rate of change of pressure over time is ΔK<lower limit value ΔKL, it can notify the terminal 47 that the separation membrane has deteriorated. Also, if the rate of change of pressure over time is ΔK>upper limit value ΔVH, it is considered that some kind of abnormality has occurred in the gas separation system 1, such as a malfunction of the hydrogen concentration meter, and the gas separation system 1 can notify the terminal 47 that an abnormality has occurred.

[0032] As described above, the gas separation system of this embodiment can detect changes in the gas permeation rate of the separation membrane, i.e., changes in the performance of the separation membrane, from changes in the pressure time rate of change of the separation membrane, so that the deterioration state of the separation membrane can be diagnosed without the need for additional concentration sensors or flow rate sensors, thereby reducing the cost of diagnosing the deterioration state of the separation membrane.

[0033] <Second embodiment> A gas separation system according to a second embodiment of the present invention will be described below with reference to Figures 6 to 8. In Figures 6 to 8 showing the second embodiment, parts corresponding to those in Figures 1 to 5 described in the first embodiment are given the same reference numerals, and duplicated explanations will be omitted.

[0034] [Gas separation system configuration] FIG. 5 is a diagram showing an example of the configuration of a gas separation system 1 according to a second embodiment of the present invention. 5, the gas separation system 1 in this embodiment has two modules: a first separation membrane module 11 and a second separation membrane module 11a. The internal structure and characteristics of each of the separation membrane modules 11 and 11a are the same as those of the separation membrane module 11 described in the first embodiment. The first separation membrane module 11 has a first separation membrane 12, and the second separation membrane module 11a has a second separation membrane 12a.

[0035] The two separation membrane modules 11 and 11a are connected in parallel. Specifically, the mixed gas supply pipe 51 branches at a branch point 101 into the mixed gas supply pipe 52 and the mixed gas supply pipe 52a, which are connected to the primary sides of the separation membrane modules 11 and 11a, respectively. Non-permeate gas pipes 53, 53a are connected to the primary sides of the separation membrane modules 11, 11a, respectively, and permeate gas pipes 56, 56a are connected to the secondary sides of the separation membrane modules 11, 11a, respectively.

[0036] The non-permeate gas pipes 53, 53a connected to the primary sides of the separation membrane modules 11, 11a merge with the non-permeate gas pipe 54 at a junction 102. The permeate gas pipes 56, 56a connected to the secondary sides of the separation membrane modules 11, 11a merge with the permeate gas pipe 57 at a junction 103.

[0037] A first control valve 21 is provided in the permeate gas pipe 57. Like the control valve 21 of the first embodiment, the first control valve 21 receives a command from the valve opening command unit 42 of the control device 41 and adjusts the valve opening. The permeate gas pipe 56 is provided with a first check valve 22 for preventing backflow. Also, a first pressure gauge 31 is provided for measuring the pressure between the secondary side of the separation membrane module 11 and the first check valve 22. The measurement value of the first pressure gauge 31 is sent to a measurement value input unit 43 of the control device 41. Similarly, the permeate gas pipe 56a is provided with a second check valve 22a to prevent backflow. A second pressure gauge 31a is also provided to measure the pressure between the secondary side of the separation membrane module 11a and the second check valve 22a. The measurement value of the second pressure gauge 31a is sent to the measurement value input unit 43 of the control device 41.

[0038] The control device 41 is the same as in the first embodiment in that it comprises a valve opening command unit 42, a measurement value input unit 43, a database 44, a pressure time rate of change calculation unit 45, and a separation membrane performance evaluation unit 46. In the control device 41 of this embodiment, the measurement value input unit 43 receives measurement values ​​from the multiple pressure gauges 31, 31a. Time-series data of the multiple pressure measurement values ​​from the pressure gauges 31, 31a is stored in a database 44 of the control device 41. A pressure time change rate calculation unit 45 of the control device 41 calculates multiple pressure time change rates. Furthermore, a separation membrane performance evaluation unit 46 in the control device 41 evaluates the performance of each of the multiple separation membranes and transmits the performance evaluation results of the multiple separation membranes to a terminal 47.

[0039] [Example of pressure measurement time series data] FIG. 6 is a diagram showing an example of time-series data of pressure measurement values ​​of the gas separation system 1 according to the second embodiment. When the second separation membrane 12a is more deteriorated than the first separation membrane 12, and when the valve opening of the control valve 21 becomes zero, the pressure on the secondary side of the second separation membrane 12a (pressure d 12 ) is the pressure on the secondary side of the first separation membrane 12 (pressure d 11) rises more slowly than Fig. 6.

[0040] [Display screen example] 7 and 8 show examples of the display screen 47a of the terminal 47. FIG. The terminal 47 receives the deterioration index value ΔK / ΔKL of the separation membrane and displays it on the screen. A display screen 47a shown in FIG. 7 shows the current degree of deterioration of each separation membrane. Display screen 47a connects the "initial state" mark and the "state requiring maintenance" mark with a straight line, and displays the performance of first separation membrane 12 and second separation membrane 12a, i.e., their current deterioration states, with two triangular marks (△ and ▽) on that line. When the respective deterioration index values ​​ΔK / ΔKL are 0, the triangular mark △ representing the first separation membrane is positioned at the "initial state" mark on the screen, and when the deterioration index value ΔK / ΔKL is 1, the triangular mark ▽ representing the second separation membrane is positioned at the "state requiring maintenance" mark on the screen.

[0041] FIG. 8 shows the change over time in the deterioration state of the separation membrane. The vertical axis represents the deterioration state of the separation membrane, and the horizontal axis represents time. Display screen 47a in FIG. 8 is a graph of the separation membrane deterioration index value ΔK / ΔKL received by terminal 47. In this case, the graph on display screen 47a displays the position of the deterioration state where separation membrane maintenance is required. From the graph of the change over time in the deterioration state of the separation membrane, it is possible to predict the time when each of the first separation membrane 12 and the second separation membrane 12a will reach a state where maintenance is required.

[0042] [Effects of the second embodiment] In the gas separation system 1 of the second embodiment, the permeate gas pipes 56, 56a connected to the secondary sides of the separation membranes 12, 12a join at a junction 103, and the permeate gas pipes 56, 56a are equipped with check valves 22, 22a. This prevents pressure increases due to backflow, making it possible to evaluate only the pressure increase due to the permeation rate of each separation membrane 12, 12a. Thus, the second embodiment allows the pressure time change rate of each separation membrane to be obtained, enabling the performance of each separation membrane to be evaluated. This reduces the frequency of membrane replacement and reduces maintenance costs.

[0043] <Third embodiment> A gas separation system according to a third embodiment of the present invention will now be described with reference to FIG. In FIG. 9, the same reference numerals are used to designate parts corresponding to those in FIGS. 1 to 8 described in the first and second embodiments, and duplicated explanations will be omitted.

[0044] [Gas separation system configuration] FIG. 9 is a diagram showing an example of the configuration of a gas separation system 1 according to the third embodiment. As shown in FIG. 9, the gas separation system 1 has two separation membrane modules 11, 11a, and the internal structure and characteristics of the separation membrane modules 11, 11a are the same as those of the separation membrane modules 11, 11a described in the second embodiment.

[0045] However, in this embodiment, the two separation membrane modules 11, 11a are connected in series on the primary side and in parallel on the secondary side. Specifically, the mixed gas supply pipe 51 is connected to the primary side of the first separation membrane module 11. A pipe 53 is connected to the primary side of the first separation membrane module 11, and the other end of the pipe 53 is connected to the primary side of the second separation membrane module 11a.

[0046] In addition, a non-permeate gas pipe 54 is connected to the primary side of the second separation membrane module 11a. A permeate gas pipe 56 is connected to the secondary side of the first separation membrane module 11, and a permeate gas pipe 56a is connected to the secondary side of the second separation membrane module 11a. The permeate gas pipes 56 and 56a merge into a permeate gas pipe 57 at a junction 103. The permeate gas pipe 57 is provided with a control valve 21. The control valve 21 is the same as the control valve 21 in the second embodiment.

[0047] The permeate gas pipe 56 is provided with a check valve 22 , and a first pressure gauge 31 is provided between the first check valve 22 and the secondary side of the first separation membrane module 11 . The pipe 56a is provided with a second check valve 22a, and a second pressure gauge 31a is provided between the second check valve 22a and the secondary side of the second separation membrane module 11a. The measured values ​​of the pressure gauges 31, 31a are transmitted to a measured value input unit 43 of the control device 41. The configuration and processing of the control device 41 are the same as those of the second embodiment.

[0048] [Effects of the third embodiment] As shown in the third embodiment, even in a configuration in which the primary sides of two separation membrane modules 11, 11a are connected in series, the pressure time change rate on the secondary side of each of multiple separation membranes 11, 11a can be calculated simultaneously, making it possible to evaluate the performance of each individual separation membrane.

[0049] <Fourth embodiment> A gas separation system according to a fourth embodiment of the present invention will now be described with reference to FIG. In FIG. 10, the same reference numerals are used to designate parts corresponding to those in FIGS. 1 to 9 described in the first to third embodiments, and duplicated explanations will be omitted.

[0050] [Gas separation system configuration] FIG. 10 is a diagram showing an example of the configuration of a gas separation system 1 according to the fourth embodiment. In FIG. 10, the gas separation system 1 has two separation membrane modules 11, 11a, and the internal structure and characteristics of the two separation membrane modules 11, 11a are the same as those of the separation membrane modules 11, 11a described in the second and third embodiments.

[0051] 10, two separation membrane modules 11, 11a are connected in series. Specifically, the mixed gas supply pipe 51 is connected to the primary side of the first separation membrane module 11. The primary side of the first separation membrane module 11 is connected to a non-permeate gas pipe 53, and the other end of the non-permeate gas pipe 53 is connected to the primary side of the second separation membrane module 11a. A non-permeate gas pipe 54 is connected to the primary side of the second separation membrane module 11a. A permeate gas pipe 56a is connected to the secondary side of the second separation membrane module 11a, and the other end of the permeate gas pipe 56a is connected to the secondary side of the first separation membrane module 11. A permeate gas pipe 56 is connected to the secondary side of the first separation membrane module 11.

[0052] A first control valve 21 is provided in the permeate gas pipe 56. In addition, a first pressure gauge 31 is provided between the first control valve 21 and the first separation membrane module 11. The second permeate gas pipe 56a is provided with a second control valve 21a, and a second pressure gauge 31a is provided between the second control valve 21a and the second separation membrane module 11a. The control valves 21, 21a receive commands from a valve opening command unit 42 of the control device 41 and adjust the valve opening.

[0053] The first pressure gauge 31 and the second pressure gauge 31 a transmit their measurement values ​​to a measurement value input unit 43 of the control device 41 . The control device 41 has the same configuration and processing as the control device 41 of the second embodiment, except for the following points: The control device 41 of this embodiment differs from the control device 41 of the second embodiment in that the valve opening command unit 42 simultaneously sends the same command to multiple (two) control valves 21, 21a.

[0054] [Effects of the fourth embodiment] In the fourth embodiment, the pressure time change rate on the secondary side of each of the plurality of separation membranes 12, 12a can also be calculated simultaneously, making it possible to evaluate the performance of each individual separation membrane.

[0055] <Fifth embodiment> A gas separation system according to a fifth embodiment of the present invention will be described below with reference to Figures 11 and 12. In Figures 11 and 12 showing the fifth embodiment, parts corresponding to those in Figures 1 to 10 described in the first to fourth embodiments are given the same reference numerals, and duplicated explanations will be omitted.

[0056] [Gas separation system configuration] FIG. 10 is a diagram showing an example of the configuration of a gas separation system 1 according to the fifth embodiment. In FIG. 11, the gas separation system 1 has two separation membrane modules 11, 11a, and the internal structure and characteristics of each separation membrane module 11, 11a are the same as those of the separation membrane modules 11, 11a described in the second to fourth embodiments.

[0057] The two separation membrane modules 11, 11a are connected in series. Specifically, the mixed gas supply pipe 51 is connected to the primary side of the first separation membrane module 11. The primary side of the first separation membrane module 11 is connected to a non-permeate gas pipe 53. A permeate gas pipe 56 is connected to the secondary side of the first separation membrane module 11, and the other end of the permeate gas pipe 56 is connected to the primary side of the second separation membrane module 11a. A non-permeate gas pipe 53a is connected to the primary side of the second separation membrane module 11a. A permeate gas pipe 56a is connected to the secondary side of the second separation membrane module 11a.

[0058] The permeation gas pipe 56 is provided with a first pressure gauge 31 . A first control valve 21 is provided in the non-permeating gas pipe 53a. The permeate gas pipe 56a is provided with a second control valve 21a. In addition, a second pressure gauge 31a is provided between the second control valve 21a and the second separation membrane module 11a.

[0059] The first control valve 21 and the second control valve 21a receive commands from a valve opening command unit 42 of the control device 41 and adjust the valve opening. The first pressure gauge 31 and the second pressure gauge 31 a transmit their measurement values ​​to a measurement value input unit 43 of the control device 41 . The control device 41 has the same configuration and processing as the control device 41 of the fourth embodiment, except for the following point: The control device 41 of this embodiment differs from the control device 41 of the fourth embodiment in that the valve opening command unit 42 sends a command to the second control valve 21a to set the valve opening to zero, and then sends a similar command to the first control valve 21 after a certain time has elapsed.

[0060] [Control device signal flow] FIG. 12 is a diagram showing the flow of signals in the control device 41 of the gas separation system 1 according to the embodiment of the present invention. The valve opening command unit 42 receives a command to perform performance evaluation from the terminal 47 and sends a command to the second control valve 21a to set the valve opening to zero (step S24). Here, when the pressure on the primary side of the second separation membrane module 11a is higher than that on the secondary side and gas is permeating the separation membrane, the administrator may operate the terminal 47 so that the terminal 47 issues a command to perform performance evaluation. Furthermore, the start-up process, shutdown process, and load change process of the gas separation system 1 may be integrated into a single process. Furthermore, after a certain time has elapsed since sending a command to the second regulating valve 21a to set the valve opening to zero, the valve opening command unit 42 sends a command to the first regulating valve 21 to set the valve opening to zero (step S27).

[0061] The measurement value input unit 43 receives the measurement values ​​of the two pressure gauges 31, 31a and transmits them to the database 44 (step S22). The database 44 stores a predetermined initial value of the pressure time rate of change, upper and lower limits of the difference between the measured value and the initial value, and also stores time-series data of the pressure measurement value. The data stored in the database 44 is transmitted to the separation membrane performance evaluation unit 46 (step S21). The pressure time change rate calculation unit 45 receives from the database 44 the time series data of the pressure measurement value of the second pressure gauge 31a from the time when a command to set the valve opening to zero is sent to the second control valve 21a to the time when a certain period of time has elapsed (step S23).

[0062] Then, the pressure time rate of change calculation unit 45 calculates the pressure time rate of change of the second pressure gauge 31a and transmits the calculated pressure time rate of change to the separation membrane performance evaluation unit 46 (step S25). The pressure time rate of change calculation unit 45 also receives from the database 44 time series data of the pressure measurement value of the first pressure gauge 31 from the time when a command to set the valve opening to zero is sent to the first control valve 21 until a certain period of time has elapsed (step S28). The pressure time rate of change calculation unit 45 then calculates the pressure time rate of change of the first pressure gauge 31 and transmits the calculated pressure time rate of change to the separation membrane performance evaluation unit 46 (step S29).

[0063] Separation membrane performance evaluation unit 46 evaluates the performance of second separation membrane 12a using the pressure time change rate of second pressure gauge 31a and transmits the performance evaluation result to terminal 47 (step S26). Also, separation membrane performance evaluation unit 46 evaluates the performance of separation membrane 12 using the pressure time change rate of pressure gauge 31 and transmits the performance evaluation result to terminal 47 (step S30).

[0064] [Effects of the fifth embodiment] In the fifth embodiment, the pressure time change rate on the secondary side of each of the plurality of separation membranes 12, 12a can also be calculated simultaneously, making it possible to evaluate the performance of each individual separation membrane.

[0065] <Modification> It should be noted that the embodiments described so far have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described.

[0066] For example, the display examples shown in Figures 7 and 8 show examples of displaying the performance of multiple separation membranes, but the display format of the performance of multiple separation membranes is not limited to the examples shown in these figures. For example, the performance of each separation membrane may be displayed as a numerical value. Furthermore, although the display examples only show the second embodiment, similar display formats can be applied to other embodiments.

[0067] In addition, the configuration diagrams shown in Figures 1, 5, 9, 10, and 11 only show control lines and information lines that are considered necessary for explanation, and do not necessarily show all control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected. Furthermore, the control flows shown in FIGS. 2 and 12 and the flowchart shown in FIG. 4 are also examples, and as long as the processing results are the same, the order of some of the processing may be changed or multiple processes may be executed simultaneously. In addition, in each of the above-described embodiments, the control device 41 is configured to include a pressure time rate of change calculation unit and a separation membrane performance evaluation unit, but the pressure time rate of change calculation unit and the separation membrane performance evaluation unit are configured, for example, by executing a program implemented in a computer. In this case, the program may be prepared in the memory or storage of the computer, or may be stored and transferred on a recording medium such as an external memory, an IC card, an SD card, or an optical disk. [Explanation of symbols]

[0068] 1...Gas separation system 2...Mixed gas supply pipe 3...Non-permeable gas piping 4...Permeation gas piping 11...Gas separation membrane module (first separation membrane module) 11a...gas separation membrane module (second separation membrane module) 12...Separation membrane (first separation membrane) 12a...Separation membrane (second separation membrane) 13...Primary side 14...Secondary side 21...Control valve (first control valve), 21a...control valve (second control valve), 22, 22a...Check valve 31...Pressure gauge (first pressure gauge) 31a... Pressure gauge (second pressure gauge) 41...Control device 41a...CPU 41b…Memory 41c…Storage 41d...Input section 41e...output section 41f...Communication interface 42...Valve opening command section 43...Measurement value input section 44...Database 45...Pressure time change rate calculation section 46…Separation Membrane Performance Evaluation Section 47...Terminal 47a…Display screen 51, 52, 52a...Mixed gas supply pipes 53, 53a, 54...Non-permeable gas piping 56, 56a, 57...Permeation gas piping 101...Fork in the road 102, 103...confluence

Claims

1. A gas separation system for evaluating performance of a separation membrane, the gas separation system comprising: a control valve for controlling a flow rate of a gas separated by the separation membrane, the control valve controlling a flow rate of the gas separated by the separation membrane; and a pressure gauge for measuring a pressure between the separation membrane and the control valve; a pressure time rate of change calculation unit that calculates a pressure time rate of change in a predetermined valve opening state using the valve opening of the control valve and time series data of the measurement value of the pressure gauge; a separation membrane performance evaluation unit that compares the pressure time change rate calculated by the pressure time change rate calculation unit with an initial value and evaluates the performance of the separation membrane. Gas separation system.

2. The separation membrane has a plurality of separation membranes, and the pressure gauge is also installed for each of the separation membranes, the regulating valve is a regulating valve that controls the flow rate of gas obtained by joining the gases discharged from the plurality of separation membranes at a joining point, Each of the pressure gauges measures the pressure on the side that has permeated each of the separation membranes. The gas separation system of claim 1 .

3. the pressure time rate of change calculation unit calculates a pressure time rate of change in a predetermined valve opening state using the valve opening of the control valve and time series data of the measurement values ​​of each of the pressure gauges; The separation membrane performance evaluation unit evaluates the performance of each of the plurality of separation membranes. The gas separation system of claim 2 .

4. an on-off valve for shutting off the flow rate of the pipe in which each of the pressure gauges is installed; The separation membrane performance evaluation unit stores, as a database, pressure measurement values ​​for a certain period of time using the pressure gauge installed in the closed piping while the on-off valve is changed from open to closed, and evaluates the performance of each of the plurality of separation membranes based on the pressure measurement values ​​stored in the database and the actually measured time-series data. The gas separation system of claim 3 .

5. The plurality of separation membranes include a first separation membrane and a second separation membrane connected in series to the first separation membrane, which separates gas discharged from a primary side of the first separation membrane; As pressure gauges, a first pressure gauge that measures the pressure in a pipe connected to the secondary side of the first separation membrane and a second pressure gauge that measures the pressure in a pipe connected to the secondary side of the second separation membrane are provided, The separation membrane performance evaluation unit evaluates the performance of the first separation membrane and the performance of the second separation membrane connected in series based on the pressure measurement value by the first pressure gauge and the pressure measurement value by the second pressure gauge. The gas separation system of claim 2 .

6. The secondary side of the first separation membrane is also connected in series with the secondary side of the second separation membrane via a pipe, the pressure time rate of change calculation unit simultaneously acquires time series data of the valve opening of the control valve and the measurement values ​​of the pressure gauges, and calculates a pressure time rate of change in a predetermined valve opening state; The separation membrane performance evaluation unit evaluates the performance of each of the plurality of separation membranes. The gas separation system of claim 5 .

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