Purifier, control method of purifier, and control program of purifier
Patent Information
- Application Number
- JP2023131735
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-08-13
- Publication Date
- 2025-02-26
Smart Images
Figure 2025026812000001_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates to a refinery apparatus, a control method for a refinery apparatus, and a control program for a refinery apparatus. [Background technology]
[0002] JP 2014-113594 A (Patent Document 1) discloses a technique for separating oxygen and nitrogen from a raw gas. The separation is achieved by a pretreatment device and an air separation device.
[0003] More specifically, the pretreatment device includes a first adsorption tower and a second adsorption tower for removing carbon dioxide gas from the air, a sensor for measuring the concentration of carbon dioxide gas in the gas before it passes through the adsorption towers, and a gas meter for measuring the amount of gas that has passed through the adsorption towers.The pretreatment device integrates the total amount of carbon dioxide gas that has passed through the adsorption towers based on the measured carbon dioxide gas concentration and the measured gas amount, and switches between adsorption and regeneration in the adsorption towers before the total amount reaches a predetermined value.
[0004] As a result, the pretreatment device described above makes effective use of the adsorbent material by avoiding switching between adsorption and regeneration when sufficient adsorption capacity remains in the adsorption tower, thereby reducing the consumption of excessive regeneration energy (see paragraph
[0010] ).
[0005] Through the above steps, the pretreatment device removes water, carbon dioxide, and nitrous oxide from the air to produce a raw gas, which is then supplied to the air separation device (see paragraph
[0024] ). The air separation device is a cold-type air separation device that cools and liquefies the raw gas supplied from the pretreatment device, and separates oxygen and nitrogen by distillation using the difference in boiling points (see paragraph
[0025] ). [Prior art documents] [Patent documents]
[0006] [Patent Document 1] JP 2014-113594 A Summary of the Invention [Problem to be solved by the invention]
[0007] High-purity oxygen gas produced by cryogenic separation contains trace amounts of impurities. In semiconductor manufacturing processes, etc., ultra-high-purity oxygen gas with extremely low levels of such impurities is desired. In particular, in recent years, with the improvement of analytical technology, the purity of oxygen gas required has become higher.
[0008] In the process of refining ultra-high purity oxygen gas from high purity oxygen gas, for example, an adsorption separation method is applied. In the adsorption separation method, impurities in high purity oxygen gas are alternately adsorbed in the first and second adsorption towers. If the adsorption in the first and second adsorption towers is switched excessively, the running costs become high. In view of this, a technology for reducing the running costs in the process of refining ultra-high purity oxygen gas from high purity oxygen gas is desired. [Means for solving the problem]
[0009] In one example of the present disclosure, a purification device for increasing the purity of raw oxygen gas produced by an oxygen production device is provided. The raw oxygen gas includes hydrocarbons and carbon dioxide. The purification device includes a catalyst tube having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide, first and second adsorption towers capable of adsorbing carbon dioxide from the raw oxygen gas that has passed through the catalyst tube, a flow sensor for detecting the flow rate of the raw oxygen gas before being sent to the first and second adsorption towers, and a control unit capable of alternately switching the connection state of pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed. The control unit reduces the frequency of switching the connection state as the flow rate decreases.
[0010] In one example of the present disclosure, the flow rate sensor is disposed upstream of the catalyst cylinder in a direction of a gas flow of the raw material oxygen gas passing through the catalyst cylinder.
[0011] In one example of the present disclosure, the refinery device switches the connection state every time an integrated amount of the flow rate reaches a predetermined amount.
[0012] In one example of the present disclosure, the purification device further includes a concentration sensor for detecting a concentration of carbon dioxide gas contained in the raw oxygen gas after the raw oxygen gas passes through the catalyst tube and before the raw oxygen gas is fed into the first and second adsorption towers. The control unit reduces the switching frequency as the concentration decreases.
[0013] In one example of the present disclosure, the refining device further includes a pressure sensor for detecting an internal pressure of the pipe. The control unit reduces the switching frequency as the internal pressure increases.
[0014] In one example of the present disclosure, the concentration of oxygen gas contained in the raw oxygen gas before passing through the catalyst column is 99.5% or more.
[0015] In one example of the present disclosure, the catalyst comprises a precious metal.
[0016] In another example of the present disclosure, a control method for a purification device for increasing the purity of raw oxygen gas produced by an oxygen production device is provided. The raw oxygen gas includes hydrocarbons and carbon dioxide. The purification device includes a catalyst tube having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide, first and second adsorption towers capable of adsorbing carbon dioxide from the raw oxygen gas that has passed through the catalyst tube, and a flow sensor for detecting the flow rate of the raw oxygen gas before being sent to the first and second adsorption towers. The control method includes a step of acquiring the flow rate from the flow sensor, and a step of alternately switching the connection state of the pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed. The lower the flow rate, the less frequently the switching step is performed.
[0017] In another example of the present disclosure, a control program for a purification device for increasing the purity of raw oxygen gas produced by an oxygen production device is provided. The raw oxygen gas includes hydrocarbons and carbon dioxide. The purification device includes a catalyst tube having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide, first and second adsorption towers capable of adsorbing carbon dioxide from the raw oxygen gas that has passed through the catalyst tube, and a flow sensor for detecting the flow rate of the raw oxygen gas before being sent to the first and second adsorption towers. The control program causes the purification device to execute a step of acquiring the flow rate from the flow sensor, and a step of alternately switching the connection state of the pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed. The lower the flow rate, the less frequently the switching step is executed.
[0018] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings. [Brief description of the drawings]
[0019] [Figure 1] FIG. 2 is a diagram showing an example of the configuration of a refining device. [Diagram 2] FIG. 2 is a schematic diagram illustrating an example of a hardware configuration of a control unit. [Diagram 3] FIG. 2 is a diagram showing an example of the configuration of a cryogenic separation device. [Figure 4] FIG. 4 is a diagram illustrating an example of a configuration of a removal mechanism. [Diagram 5] FIG. 2 is a diagram showing a piping connection state of the adsorption separation device. [Figure 6] FIG. 2 is a diagram showing a piping connection state of the adsorption separation device. [Figure 7] 13 is a flowchart showing the flow of a connection state switching process. [Figure 8] FIG. 13 is a diagram for explaining a simulation of the frequency of switching the connection state when a flow sensor is not used. [Figure 9] FIG. 13 is a diagram for explaining a simulation of the frequency of switching the connection state when a flow rate of high-purity oxygen gas detected by a flow sensor is used. [Figure 10] FIG. 2 is a diagram showing a configuration of a removal mechanism. [Figure 11] 13 is a flowchart showing the flow of a connection state switching process. [Figure 12] 13 is a diagram for explaining a simulation of the frequency of switching of the connection state when the flow rate of high-purity oxygen gas detected by a flow rate sensor and the concentration of carbon dioxide gas detected by a concentration sensor are used. FIG. [Figure 13] FIG. 2 is a diagram showing a piping connection state of the adsorption separation device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Hereinafter, each embodiment according to the present invention will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. Note that each embodiment and each modification described below may be selectively combined as appropriate.
[0021] <A. Purification device 100> First, with reference to FIG. 1, a purification device 100 for purifying ultra-high purity oxygen gas from high-purity oxygen gas will be described.
[0022] The "high-purity oxygen gas" is the raw material oxygen gas produced by an oxygen production device. The oxygen production device is, for example, a device that produces raw material oxygen gas from air by a cryogenic separation method. The oxygen gas concentration in the high-purity oxygen gas is higher than the concentration of other gases. As an example, the oxygen gas concentration in the high-purity oxygen gas is 99.5% or more and 99.9% or less. More specifically, the oxygen gas concentration in the high-purity oxygen gas is 99.8% or more and 99.9% or less. The impurities contained in the high-purity oxygen gas include, for example, hydrocarbons and carbon dioxide gas (carbon dioxide, CO2).
[0023] The "hydrocarbons" are compounds containing at least carbon atoms and hydrogen atoms. Examples of hydrocarbons include methane gas, ethane gas, and propane gas. Most of the hydrocarbons contained in the high-purity oxygen gas are methane gas, and the rest are ethane gas, propane gas, and the like.
[0024] "Ultra-high purity oxygen gas" refers to a product gas in which the purity of high purity oxygen gas is further increased by the purification apparatus 100 according to this embodiment. The concentration of oxygen gas in ultra-high purity oxygen gas is higher than the concentration of oxygen gas in high purity oxygen gas. As an example, the oxygen gas concentration in ultra-high purity oxygen gas is higher than 99.9%. In other words, the concentration of impurities in ultra-high purity oxygen gas is lower than 0.1%. Preferably, the concentration of impurities in ultra-high purity oxygen gas is 1 ppb (parts per billion) or less. Ultra-high purity oxygen gas can be used for various purposes. As an example, ultra-high purity oxygen gas is used in the semiconductor manufacturing process.
[0025] Fig. 1 is a diagram showing an example of the configuration of a refining apparatus 100. As shown in Fig. 1, the refining apparatus 100 includes a control unit 50, a hydrocarbon removal mechanism 140, an adsorption / separation apparatus 300, and pipes F10 and F20. The removal mechanism 140 includes a flow rate sensor 150 and a catalyst cylinder 200. The adsorption / separation apparatus 300 includes adsorption towers 300A and 300B (first and second adsorption towers).
[0026] The pipe F10 is a gas flow passage for guiding high-purity oxygen gas to the catalyst cylinder 200. The pipe F10 may be configured as a single pipe, or may be configured as a plurality of pipes.
[0027] The pipe F20 is a gas flow path for guiding the high-purity oxygen gas that has passed through the catalyst cylinder 200 to the adsorption separation device 300. The pipe F20 branches at a branch point P2 and connects the catalyst cylinder 200 to the adsorption towers 300A and 300B. That is, the pipe F20 connects the catalyst cylinder 200 to the adsorption towers 300A and 300B. The pipe F20 may be composed of a single pipe or may be composed of multiple pipes.
[0028] The catalyst cylinder 200 has a catalyst for converting the hydrocarbons contained in the high-purity oxygen gas into carbon dioxide. The catalyst is heated by a heat source such as a heater. As a result, the hydrocarbons that come into contact with the catalyst are oxidized and converted into carbon dioxide and moisture.
[0029] The high-purity oxygen gas that has passed through the catalyst cylinder 200 is sent to either the adsorption tower 300A or 300B via pipe F20. The adsorption towers 300A and 300B adsorb carbon dioxide gas from the high-purity oxygen gas that has passed through the catalyst cylinder 200. The adsorption towers 300A and 300B alternately adsorb carbon dioxide gas by switching the connection state of the pipe F20.
[0030] More specifically, the connection state of the pipe F20 has a connection state S1 and a connection state S2. The connection state S1 is a piping connection state in which the adsorption tower 300A adsorbs carbon dioxide gas while the adsorption tower 300B guides high-purity oxygen gas so that the adsorption tower 300B desorbs the carbon dioxide gas previously adsorbed. The connection state S2 is a piping connection state in which the adsorption tower 300B adsorbs carbon dioxide gas while the adsorption tower 300A guides high-purity oxygen gas so that the adsorption tower 300A desorbs the carbon dioxide gas previously adsorbed.
[0031] The control unit 50 alternately switches the connection state of the pipe F20 between the connection state S1 and the connection state S2. At this time, if the connection states S1 and S2 are switched while the adsorption towers 300A and 300B still have adsorption capacity, the running costs of the adsorption and separation device 300 will increase. Therefore, the control unit 50 switches the connection states S1 and S2 after using as much of the adsorption capacity of the adsorption towers 300A and 300B as possible.
[0032] More specifically, the purification device 100 is provided with a flow rate sensor 150 for detecting the flow rate of the high-purity oxygen gas before it is sent to the adsorption towers 300A and 300B. The flow rate indicates, for example, the volume of the high-purity oxygen gas flowing through the pipe F10 per unit time.
[0033] There is no particular limitation on the type of the flow sensor 150. As an example, the flow sensor 150 may be a thermal mass flow meter, an electromagnetic flow meter, a Karman vortex flow meter, an ultrasonic flow meter, a Coriolis flow meter, or a differential pressure flow meter.
[0034] The flow rate of high-purity oxygen gas detected by the flow sensor 150 is periodically output to the control unit 50. The lower the detected flow rate of high-purity oxygen gas, the less frequently the control unit 50 switches between the connection states S1, S2. In other words, the higher the detected flow rate of high-purity oxygen gas, the more frequently the control unit 50 switches between the connection states S1, S2.
[0035] Typically, the frequency of switching between the connection states S1 and S2 is less than the frequency of switching based on the maximum allowable flow rate of high-purity oxygen gas (i.e., the guaranteed value). The controller 50 reduces the frequency of switching between the connection states S1 and S2 as the flow rate of high-purity oxygen gas detected by the flow sensor 150 becomes lower than the predetermined maximum allowable flow rate.
[0036] Switching the connection states S1, S2 based on the flow rate of high-purity oxygen gas has the following advantages. Frequent switching between the connection states S1, S2 means that the connection states S1, S2 are switched before the adsorption capacity of the adsorbent in the adsorption towers 300A, 300B is fully used up. The time to replace the adsorbent filled in the adsorption towers 300A, 300B may be determined based on the number of times the connection states S1, S2 are switched. Therefore, if the connection states S1, S2 are switched frequently, the adsorbent will be replaced with new one before it is worn out.
[0037] On the other hand, the purification apparatus 100 according to the present embodiment switches between the connection states S1 and S2 depending on the flow rate of high-purity oxygen gas, and therefore does not need to switch between the connection states S1 and S2 based on the flow rate of high-purity oxygen gas that is assumed to be the maximum allowable amount. As a result, the connection states S1 and S2 can be switched when the adsorption capacity of the adsorbent in the adsorption towers 300A and 300B is fully used up. As a result, the frequency of switching between the connection states S1 and S2 is reduced, and the running costs of the adsorption towers 300A and 300B are reduced.
[0038] Preferably, the control unit 50 switches the connection states S1 and S2 each time the integrated amount of the high-purity oxygen gas detected by the flow sensor 150 reaches a predetermined amount. More specifically, the control unit 50 multiplies the average flow rate of the high-purity oxygen gas by the elapsed time since the previous switching of the connection states S1 and S2, and calculates the multiplication result as the integrated amount of the high-purity oxygen gas. The control unit 50 periodically executes such a calculation process, and switches the connection states S1 and S2 based on the fact that the calculated integrated amount exceeds a predetermined amount. Thereby, the purification apparatus 100 can accurately recognize the total amount of the high-purity oxygen gas introduced into the purification apparatus 100, and can use the adsorption capacities of the adsorption towers 300A and 300B more efficiently without waste.
[0039] In the example of FIG. 1, the flow sensor 150 is disposed upstream of the catalyst cylinder 200 in the direction of the air flow through which the high-purity oxygen gas passes through the catalyst cylinder 200. However, the flow sensor 150 can be disposed at any position on the pipe before being fed into the catalyst cylinder 200. As an example, the catalyst cylinder 200 may be disposed on the pipe F10, or may be provided in the pipe F20 until the high-purity oxygen gas is fed from the catalyst cylinder 200 to the adsorption towers 300A and 300B.
[0040] <B. Hardware Configuration of Control Unit 50> Next, with reference to FIG. 2, the hardware configuration of the control unit 50 shown in FIG. 1 described above will be described in order. FIG. 2 is a schematic diagram showing an example of the hardware configuration of the control unit 50.
[0041] The control unit 50 includes a control circuit 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a communication interface 104, and an auxiliary storage device 120. These components are connected to a bus 110.
[0042] The control circuit 101 is configured, for example, by at least one integrated circuit. The integrated circuit may be configured, for example, by at least one central processing unit (CPU), at least one graphics processing unit (GPU), at least one application specific integrated circuit (ASIC), at least one field programmable gate array (FPGA), or a combination thereof.
[0043] The control circuit 101 controls the operation of the control unit 50 by executing various programs such as a control program 122. The control program 122 is a program for implementing the switching process between the above-mentioned connection states S1 and S2 (see FIG. 1). Upon receiving an execution command for the control program 122, the control circuit 101 reads the control program 122 from the auxiliary storage device 120 or the ROM 102 to the RAM 103. The RAM 103 functions as a working memory and temporarily stores various data required for the execution of the control program 122.
[0044] The communication interface 104 is an interface for performing periodic communication with external devices using a field network. The external devices include, for example, the above-mentioned flow rate sensor 150, a concentration sensor 160 (see FIG. 10) described below, and a pressure sensor 170 (see FIG. 13) described below. As the field network, for example, EtherCAT (registered trademark), EtherNet / IP (registered trademark), CC-Link (registered trademark), CompoNet (registered trademark), or the like is adopted.
[0045] The auxiliary storage device 120 is a storage medium such as a hard disk or a flash memory, for example. The auxiliary storage device 120 stores a control program 122 and the like. Note that the storage location of the control program 122 is not limited to the auxiliary storage device 120, and it may be stored in the storage area of the control circuit 101 (such as a cache memory), the ROM 102, the RAM 103, an external device (such as a server), or the like.
[0046] The control program 122 may be provided by being incorporated into a part of an arbitrary program instead of as a single program. In this case, various processes according to the present embodiment are realized in cooperation with an arbitrary program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 122 according to the present embodiment. Further, a part or all of the functions provided by the control program 122 may be realized by dedicated hardware. Further, the control unit 50 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 122.
[0047] <C. Cryogenic Separation Device 10> Next, with reference to FIG. 3, the cryogenic separation device 10 will be described. FIG. 3 is a diagram showing an example of the configuration of the cryogenic separation device 10.
[0048] The cryogenic separation device 10 is an oxygen production device that produces high-purity oxygen gas. The cryogenic separation device 10 produces high-purity oxygen gas from air by utilizing the difference in boiling points of various gases (such as oxygen gas, nitrogen gas, argon gas, etc.) contained in the air.
[0049] As an example, the cryogenic separation device 10 includes a filter 12, a compressor 14, an adsorber 18, a heat exchanger 20, and a rectification column 22.
[0050] First, the air taken into the cryogenic separation device 10 is sent to the filter 12. The filter 12 removes impurities from the taken-in air. The air from which the impurities have been removed is sent to the compressor 14.
[0051] The compressor 14 compresses the air from which the impurities have been removed, and makes the various gases contained in the air easier to liquefy. As an example, the compressor 14 pressurizes the air to about 0.5 MPa. The compressed air is sent to the adsorber 18.
[0052] The adsorber 18 adsorbs and removes moisture and carbon dioxide gas from the compressed air sent from the compressor 14. For example, a TSA (Thermal Swing Adsorption) method is used as the adsorption and removal method.
[0053] The TSA adsorber 18 has two adsorption towers. While one adsorption tower is adsorbing moisture and carbon dioxide gas, the other adsorption tower releases the previously adsorbed moisture and carbon dioxide gas into the atmosphere. Each adsorption tower alternately repeats adsorption and release to adsorb and remove moisture and carbon dioxide gas from the compressed air. The compressed air that has passed through the adsorber 18 is then sent to the heat exchanger 20.
[0054] The heat exchanger 20 exchanges heat between the air sent from the adsorber 18 and oxygen gas shown in Fig. 3, and cools the air to about -180°C. As a result, various gases contained in the air (for example, oxygen gas, nitrogen gas, argon gas, etc.) are liquefied, and the air is sent to the distillation tower 22 as liquefied air.
[0055] The distillation column 22 utilizes the difference in boiling points of various gases to refine liquid air into oxygen gas, liquid oxygen, liquid nitrogen, liquid argon, etc. The boiling point of liquid nitrogen at atmospheric pressure is -195.8°C, the boiling point of liquid argon at atmospheric pressure is -185.7°C, and the boiling point of liquid oxygen at atmospheric pressure is -183.0°C.
[0056] The fractionator 22 is composed of, for example, a lower tower 22A and an upper tower 22B. The liquid air is sent to the lower tower 22A. The lower tower 22A is a high-pressure tower having a higher internal pressure than the upper tower 22B.
[0057] The bottom of the upper column 22B and the top of the lower column 22A are thermally connected by a condenser (not shown). By supplying heat in the form of latent heat from the lower column 22A to the upper column 22B, the nitrogen gas accumulated at the top of the lower column 22A is condensed, generating reflux liquid nitrogen. The liquid nitrogen accumulates in a storage chamber (not shown) provided in the upper part of the lower column 22A.
[0058] The liquid air accumulated in the lower part of the lower column 22A is sent to the upper column 22B. Due to the difference in boiling points of various gases, liquid oxygen accumulates at the bottom of the upper column 22B.
[0059] Also, by supplying heat in the form of latent heat from the lower column 22A to the upper column 22B, the liquid oxygen at the bottom of the upper column 22B vaporizes, and high-purity oxygen gas is generated above the liquid oxygen. The high-purity oxygen gas is extracted from the upper column 22B and sent to the heat exchanger 20. The heat exchanger 20 performs heat exchange between the high-purity oxygen gas and the air sent from the adsorber 18, raising the temperature of the high-purity oxygen gas.
[0060] The high-purity oxygen gas that has passed through the heat exchanger 20 is supplied to the purification device 100 from the above-mentioned pipe F10 (see FIG. 1). Note that the high-purity oxygen gas may be directly supplied to the purification device 100 from the cryogenic separation device 10, or may be indirectly sent to the purification device 100 after being filled in a cylinder or the like, or may be indirectly supplied after being filled in a cylinder or the like.
[0061] <D. Removal mechanism 140> Next, with reference to FIG. 4, the configuration of the removal mechanism 140 shown in FIG. 1 will be described in detail. FIG. 4 is a diagram showing an example of the configuration of the removal mechanism 140.
[0062] The removal mechanism 140 is a mechanism for removing hydrocarbons from the high-purity oxygen gas produced by the cryogenic separation device 10. As shown in FIG. 4, the removal mechanism 140 includes the above-mentioned flow sensor 150, heat exchanger 152, heater 154, catalyst cylinder 200, and cooler 202.
[0063] The high-purity oxygen produced in the above-mentioned cryogenic separation apparatus 10 is sent to the heat exchanger 152. The heat exchanger 152 exchanges heat between the high-purity oxygen before passing through the catalyst tube 200 and the high-purity oxygen after passing through the catalyst tube 200. Typically, the heat exchanger 152 transfers heat from the high-purity oxygen after passing through the catalyst tube 200 to the high-purity oxygen before passing through the catalyst tube 200. The high-purity oxygen gas with the increased temperature is sent to the heater 154.
[0064] The heater 154 heats the high-purity oxygen gas so that a catalytic reaction easily occurs in the catalyst tube 200. The high-purity oxygen gas heated by the heater 154 is sent to the catalyst tube 200.
[0065] The catalyst tube 200 has a catalyst capable of converting hydrocarbons contained in the high-purity oxygen gas into carbon dioxide gas through an oxidation reaction. The catalyst may be, for example, a precious metal or a metal other than a precious metal. Examples of precious metal catalysts include palladium, platinum, gold, silver, rhodium, and ruthenium. The precious metal catalyst is supported on an inorganic porous material (not shown). Examples of inorganic porous materials include alumina, titania silica, silica alumina, and zirconia. Examples of metal catalysts other than precious metals include nickel and copper.
[0066] The catalyst in the catalyst tube 200 is heated by a heat source such as a heater. This causes the catalyst to oxidize the hydrocarbons that it comes into contact with. As a result, the hydrocarbons contained in the high-purity oxygen gas are converted into carbon dioxide gas and moisture. With regard to methane gas, which is an example of a hydrocarbon, a catalytic reaction based on the following formula (1) occurs in the catalyst tube 200.
[0067] CH4 + 2O2 → CO2 + 2H2O (1) The high-purity oxygen gas that has passed through the catalyst cylinder 200 is returned to the heat exchanger 152. The heat exchanger 152 performs heat exchange between the high-purity oxygen before passing through the catalyst cylinder 200 and the high-purity oxygen after passing through the catalyst cylinder 200, and reduces the temperature of the high-purity oxygen after passing. The high-purity oxygen gas with the reduced temperature is sent to the cooler 202.
[0068] The cooler 202 further reduces the temperature of the high-purity oxygen gas that has passed through the heat exchanger 152. The method of cooling the high-purity oxygen gas is arbitrary. As an example, the cooler 202 reduces the temperature of the high-purity oxygen gas with cooling water. The high-purity oxygen gas that has passed through the cooler 202 is sent to the adsorption separation device 300.
[0069] In addition, in the example of FIG. 4, the above-described flow rate sensor 150 is provided on the pipe before flowing into the heat exchanger 152, but the flow rate sensor 150 can be provided at any position on the pipe from the inlet of the high-purity oxygen gas to the adsorption separation device 300. As an example, the flow rate sensor 150 may be provided on the pipe connecting between the heat exchanger 152 and the heater 154. As another example, the flow rate sensor 150 may be provided on the pipe connecting between the heat exchanger 152 and the cooler 202. Further, as another example, the flow rate sensor 150 may be provided on the pipe connecting between the cooler 202 and the adsorption separation device 300.
[0070] <E. Adsorption separation device 300> Next, with reference to FIGS. 5 and 6, the adsorption separation device 300 shown in FIG. 1 will be further described. FIG. 5 is a diagram showing the connection state S1 of the pipes of the adsorption separation device 300. FIG. 6 is a diagram showing the connection state S2 of the pipes of the adsorption separation device 300.
[0071] The high-purity oxygen gas that has passed through the above-described removal mechanism 140 is sent to either the adsorption towers 300A or 300B. The adsorption towers 300A and 300B are each filled with an adsorbent for removing carbon dioxide gas and water. Examples of the adsorbent include alumina and zeolite.
[0072] Whether the high-purity oxygen gas is sent to the adsorption towers 300A and 300B is switched depending on whether the valves V1 to V8 are opened or closed. The opening and closing of the valves V1 to V8 is controlled by the control unit 50 described above.
[0073] More specifically, in the connection state S1, the control unit 50 controls the valves V1, V4, V6, and V7 to be open, and controls the valves V2, V3, V5, and V8 to be closed.
[0074] As a result, the high-purity oxygen gas that has passed through the removal mechanism 140 is sent to the adsorption tower 300A. The adsorption tower 300A adsorbs unnecessary gases such as carbon dioxide gas and moisture from the high-purity oxygen gas. On the other hand, oxygen gas that is difficult to adsorb to the adsorbent passes through the adsorption tower 300A. In this way, the adsorption separation device 300 produces ultra-high purity oxygen gas.
[0075] A portion of the produced ultra-high purity oxygen gas is sent to the adsorption tower 300B as a self-gas for regeneration. The adsorption tower 300B is provided with a heat source such as a heater (not shown), and the unwanted gas previously adsorbed in the adsorption tower 300B is desorbed from the adsorbent by heating with the heat source. The desorbed unwanted gas is discharged into the atmosphere as an exhaust gas together with the self-gas for regeneration.
[0076] In addition, in the connection state S2, the control unit 50 controls the valves V2, V3, V5, and V8 to be in an open state, and controls the valves V1, V4, V6, and V7 to be in a closed state.
[0077] As a result, the high-purity oxygen gas that has passed through the removal mechanism 140 is sent to the adsorption tower 300B. The adsorption tower 300B adsorbs unnecessary gases such as carbon dioxide gas and moisture from the high-purity oxygen gas. On the other hand, oxygen gas that is difficult to adsorb to the adsorbent passes through the adsorption tower 300B. In this way, the adsorption separation device 300 produces ultra-high purity oxygen gas.
[0078] A portion of the produced ultra-high purity oxygen gas is sent to the adsorption tower 300A as the own gas for regeneration. The adsorption tower 300A is provided with a heat source such as a heater (not shown), and the unwanted gas previously adsorbed in the adsorption tower 300A is desorbed from the adsorbent by heating with the heat source. The desorbed unwanted gas is discharged into the atmosphere as exhaust gas together with the own gas for regeneration.
[0079] In this manner, the adsorption / separation apparatus 300 produces ultra-high purity oxygen gas by alternately repeating the adsorption and desorption of unnecessary gases between the adsorption towers 300A and 300B.
[0080] <F.フローチャート> Next, a control flow relating to the connection states S1, S2 of the adsorption / separation device 300 will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the flow of the process of switching between the connection states S1, S2.
[0081] 7 is realized by executing the above-mentioned control program 122 (see FIG. 2) by the control unit 50 of the refining device 100. In another aspect, a part or all of the process may be executed by circuit elements or other hardware.
[0082] In step S110, the control unit 50 initializes the time that has elapsed since the above-mentioned connection state S1, S2 (see FIG. 5 and FIG. 6) was last switched, and starts counting the elapsed time.
[0083] In step S112, the control unit 50 acquires the flow rate of the high-purity oxygen gas from the above-mentioned flow rate sensor 150. The flow rate indicates, for example, the average flow rate of the high-purity oxygen gas per unit time.
[0084] The control unit 50 calculates the integrated amount of the flow rate of the high-purity oxygen gas based on the acquired flow rate. Any method can be used to calculate the integrated amount. As an example, the control unit 50 multiplies the flow rate detected by the flow rate sensor 150 by the counted elapsed time, and calculates the multiplication result as the integrated amount of the high-purity oxygen gas.
[0085] In step S120, the control unit 50 judges whether the integrated amount calculated in step S112 has reached a predetermined amount. The predetermined amount may be constant or may be arbitrarily set by the user. If the control unit 50 judges that the integrated amount calculated in step S112 has reached the predetermined amount (YES in step S120), the control unit 50 switches control to step S122. If not (NO in step S120), the control unit 50 returns control to step S112.
[0086] In step S122, the control unit 50 switches the piping connection states S1, S2 of the adsorption and separation device 300 to a state different from the current state. That is, if the current piping connection state of the adsorption and separation device 300 is the connection state S1, the control unit 50 switches the piping connection state from the connection state S1 to the connection state S2. On the other hand, if the current piping connection state of the adsorption and separation device 300 is the connection state S2, the control unit 50 switches the piping connection state from the connection state S2 to the connection state S1.
[0087] <G.シミュレーション> As described above, the refining apparatus 100 according to this embodiment reduces the frequency of switching the connection states S1, S2 (see Figs. 5 and 6) of the adsorption / separation apparatus 300 as the flow rate of high-purity oxygen gas detected by the flow sensor 150 decreases. The inventors conducted a simulation to confirm how much the switching frequency decreases by switching the connection states S1, S2 based on the flow rate of high-purity oxygen gas. The simulation will be described below with reference to Figs. 8 and 9. Note that in the simulation, hydrocarbons are considered in terms of methane gas.
[0088] FIG. 8 is a diagram for explaining a simulation SMX of the switching frequency of the connection states S1, S2 in the case where the above-mentioned flow sensor 150 is not used.
[0089] In the simulation SMX, since the flow rate of the high-purity oxygen gas input to the purification device 100 is unknown, it is necessary to set the switching interval of the connection states S1 and S2 at the flow rate of the high-purity oxygen gas that is the maximum guaranteed value. 3 / h.
[0090] In addition, since the concentration of methane gas contained in the high purity oxygen gas varies depending on the operating conditions of the cryogenic separation device 10, the concentration of methane gas must also be set to the maximum guaranteed value. In the simulation SMX, the concentration of methane gas in the high purity oxygen gas was set to the maximum concentration of 25 ppm. In the simulation SMX, the concentration of carbon dioxide gas contained in the high purity oxygen gas after passing through the catalyst tube 200 was set to 25 ppm.
[0091] In this case, the adsorption rate of carbon dioxide in the adsorption towers 300A and 300B is 0.25 m 3 / h(=10×1000×25×10 -6 )
[0092] The maximum adsorption amount of carbon dioxide gas in the adsorption towers 300A and 300B is set to 5 L, respectively. In this case, the switching interval between the connection states S1 and S2 is 20 hours (=5 / 0.25). As a result, the switching frequency between the connection states S1 and S2 per 30 days is 36 times (=30×24 / 20).
[0093] As shown in the above formula (1), the high-purity oxygen gas after passing through the catalyst tube 200 contains not only carbon dioxide gas but also moisture as an impurity. However, when alumina or zeolite is used as the adsorbent in the adsorption towers 300A and 300B, the carbon dioxide gas adsorption capacity is less than one-tenth of the moisture adsorption capacity. In other words, the removal of moisture in the high-purity oxygen gas is completed earlier than the removal of carbon dioxide gas in the high-purity oxygen gas. Therefore, a simulation can be performed based on the carbon dioxide gas adsorption capacity.
[0094] FIG. 9 is a diagram for explaining a simulation SM1 of the switching frequency of the connection states S1, S2 in the case where the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 is used.
[0095] In the simulation SM1, the total amount of high-purity oxygen gas input to the refining device 100 is calculated, so there is no need to set the switching interval between the connection states S1 and S2 at a flow rate of high-purity oxygen gas that is premised on the maximum guaranteed value.
[0096] More specifically, the flow rate of the detected high purity oxygen gas is 5m 3 / h, the adsorption rate of carbon dioxide in the adsorption towers 300A and 300B is 0.125 m 3 / h(=5×1000×25×10 -6 ) The switching interval between the connection states S1 and S2 is 40 hours (=5 / 0.125). Furthermore, the switching frequency between the connection states S1 and S2 per 30 days is 18 times (=30×24 / 40).
[0097] The detected flow rate of high purity oxygen gas was 7m 3 / h, the adsorption rate of carbon dioxide in the adsorption towers 300A and 300B is 0.175 m 3 / h(=7×1000×25×10 -6 ) The switching interval between the connection states S1 and S2 is about 28.6 hours (=5 / 0.175). Furthermore, the switching frequency between the connection states S1 and S2 per 30 days is about 25.2 times (=30×24 / 28.6).
[0098] The detected flow rate of high purity oxygen gas was 9m 3 / h, the adsorption rate of carbon dioxide in the adsorption towers 300A and 300B is 0.25 m 3 / h(=9×1000×25×10 -6 ) The switching interval between the connection states S1 and S2 is 20 hours (=5 / 0.25). Furthermore, the switching frequency between the connection states S1 and S2 per 30 days is 36 times (=30×24 / 20).
[0099] As described above, when the connection states S1 and S2 of the adsorption separation device 300 are switched based on the flow rate of the high-purity oxygen gas, there is no need to switch the connection states S1 and S2 based on the flow rate of the high-purity oxygen gas assuming the maximum guaranteed value. As a result, the adsorption capacity of the adsorbent can be fully utilized, and the switching frequency of the connection states S1 and S2 can be reduced.
[0100] <H. Modification Example 1>
[0101] (H1. Overview) Next, the purification device 100 according to Modification Example 1 will be described.
[0102] The above-described purification device 100 switched the connection states S1 and S2 of the adsorption separation device 300 based on the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150. In contrast, the purification device 100 according to this modification example switches the connection states S1 and S2 of the adsorption separation device 300 based not only on the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 but also on the concentration of carbon dioxide gas contained in the high-purity oxygen gas.
[0103] Note that since other aspects such as the hardware configuration of the purification device 100 are as described above, the descriptions thereof will not be repeated below.
[0104] (H2. Concentration Sensor 160) First, with reference to FIG. 10, the concentration sensor 160 for detecting the concentration of carbon dioxide gas contained in the high-purity oxygen gas will be described. FIG. 10 is a diagram showing the configuration of the removal mechanism 140 according to this modification example.
[0105] Note that the removal mechanism 140 shown in FIG. 10 is different from the removal mechanism 140 shown in FIG. 4 in that it further includes a concentration sensor 160. Since the configurations other than the concentration sensor 160 are as described in FIG. 4, the descriptions thereof will not be repeated.
[0106] The concentration sensor 160 detects the concentration of carbon dioxide gas contained in the high-purity oxygen gas. The type of the concentration sensor 160 is not particularly limited. As an example, the concentration sensor 160 is a non-dispersive infrared (NDIR) type sensor. Alternatively, the concentration sensor 160 may be a cavity ring-down spectroscopy (CRDS) type sensor. Alternatively, the concentration sensor 160 may be a laser type gas analyzer. Alternatively, the concentration sensor 160 may be a mass spectrometer. Alternatively, the concentration sensor 160 may be a gas chromatograph.
[0107] The concentration sensor 160 is provided on a pipe after the high-purity oxygen gas has passed through the catalyst tube 200 and before the high-purity oxygen gas is fed into the adsorption towers 300A, 300B, and detects the concentration of carbon dioxide gas contained in the high-purity oxygen gas passing through the pipe. In the example of Fig. 10, the concentration sensor 160 is disposed downstream of the cooler 202 in the direction of the airflow of the high-purity oxygen gas passing through the cooler 202. In other words, the concentration sensor 160 is provided on a pipe between the cooler 202 and the adsorption separation device 300.
[0108] The control unit 50 reduces the frequency of switching between the connection states S1 and S2 as the concentration of carbon dioxide detected by the concentration sensor 160 decreases. In other words, the control unit 50 increases the frequency of switching between the connection states S1 and S2 as the concentration of carbon dioxide detected by the concentration sensor 160 increases.
[0109] More specifically, the control unit 50 determines the switching interval between the connection states S1 and S2 based on a predetermined calculation formula. The calculation formula uses at least one of the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 and the concentration of the carbon dioxide gas detected by the concentration sensor 160 as an explanatory variable, and uses the switching interval between the connection states S1 and S2 as an objective variable.
[0110] The above calculation formula is defined so that the switching interval between the connection states S1 and S2 becomes longer as the flow rate of the high-purity oxygen gas detected by the flow sensor 150 decreases. As an example, the switching interval is proportional to the flow rate.
[0111] The above formula is also defined so that the interval between switching the connection states S1 and S2 becomes longer as the concentration of carbon dioxide detected by the concentration sensor 160 decreases. As an example, the interval is proportional to the concentration.
[0112] (H3. Flowchart) Next, a control flow relating to the connection states S1 and S2 of the adsorption / separation device 300 will be described with reference to Fig. 11. Fig. 11 is a flowchart showing the flow of the process of switching between the connection states S1 and S2.
[0113] In the flowchart shown in Fig. 11, the process of step S114 is added compared to the flowchart shown in Fig. 7. Also, in the flowchart shown in Fig. 11, the process of step S120A is executed instead of step S120 shown in Fig. 7. As the other points are as described in Fig. 7, the description thereof will not be repeated.
[0114] In step S114, the control unit 50 acquires the concentration of carbon dioxide gas contained in the high-purity oxygen gas from the concentration sensor 160. Next, the control unit 50 calculates the integrated amount of carbon dioxide gas based on the acquired concentration. As an example, the control unit 50 multiplies the integrated amount of high-purity oxygen gas calculated in step S112 by the acquired concentration, and calculates the multiplication result as the integrated amount of carbon dioxide gas. This specifies the total amount of carbon dioxide gas fed to the adsorption / separation device 300.
[0115] In step S120A, the control unit 50 judges whether the integrated amount calculated in step S114 has reached a predetermined amount. The predetermined amount may be constant or may be arbitrarily set by the user. When the control unit 50 judges that the integrated amount calculated in step S114 has reached the predetermined amount (YES in step S120A), the control unit 50 switches the control to step S122, and switches the connection states S1 and S2 of the pipes in the adsorption / separation device 300 to be different from the current state. When the control unit 50 has not judged that the integrated amount calculated in step S114 has reached the predetermined amount (YES in step S120A), the control unit 50 returns the control to step S112.
[0116] (H4.Simulation) The inventors have confirmed by simulation how much the switching frequency of the connection states S1 and S2 according to this modified example is reduced by the switching process. The results of the simulation will be described below with reference to FIG.
[0117] FIG. 12 is a diagram for explaining a simulation SM2 of the switching frequency of the connection states S1, S2 when the flow rate of high-purity oxygen gas detected by the flow sensor 150 and the concentration of carbon dioxide gas detected by the concentration sensor 160 are used.
[0118] In the simulations SMX and SM2, similarly to the above-mentioned simulations SMX and SM1 (see FIGS. 8 and 9), the maximum adsorption amounts of carbon dioxide gas in the adsorption towers 300A and 300B were set to 5 L, respectively.
[0119] In the simulation SM2, the total amount of carbon dioxide gas fed into the catalyst cylinder 200 is calculated, so there is no need to set the switching interval between the connection states S1 and S2 at a flow rate of carbon dioxide gas that is premised on the maximum guaranteed value.
[0120] More specifically, when the flow rate of the high purity oxygen gas detected by the flow sensor 150 is 5 m 3 / h, and the carbon dioxide gas concentration detected by the concentration sensor 160 is 5 ppm, the carbon dioxide gas adsorption speed of the adsorption towers 300A and 300B is 0.025 m 3 / h(=5×1000×5×10 -6 ) The switching interval between the connection states S1 and S2 is 200 hours (=5 / 0.025). Furthermore, the switching frequency between the connection states S1 and S2 per 30 days is 3.6 times (=30×24 / 200).
[0121] In addition, the flow rate of the high-purity oxygen gas detected by the flow sensor 150 is 5 m 3 / h, and the carbon dioxide gas concentration detected by the concentration sensor 160 is 10 ppm, the carbon dioxide gas adsorption speed of the adsorption towers 300A and 300B is 0.05 m 3 / h(=5×1000×10×10 -6 ) The switching interval between the connection states S1 and S2 is 100 hours (=5 / 0.05). The switching frequency between the connection states S1 and S2 per 30 days is 7.2 times (=30×24 / 100).
[0122] In addition, the flow rate of the high-purity oxygen gas detected by the flow sensor 150 is 5 m 3 / h, and the carbon dioxide gas concentration detected by the concentration sensor 160 is 25 ppm, the carbon dioxide gas adsorption speed of the adsorption towers 300A and 300B is 0.125 m 3 / h(=5×1000×25×10 -6 ) The switching interval between the connection states S1 and S2 is 40 hours (=5 / 0.125). Furthermore, the switching frequency between the connection states S1 and S2 per 30 days is 18 times (=30×24 / 40).
[0123] In addition, the flow rate of the high-purity oxygen gas detected by the flow sensor 150 is 10 3 / h, and the carbon dioxide gas concentration detected by the concentration sensor 160 is 5 ppm, the carbon dioxide gas adsorption speed of the adsorption towers 300A and 300B is 0.05 m 3 / h(=10×1000×5×10 -6) It becomes 100 h (= 5 / 0.05). Further, the switching frequency of the connection states S1 and S2 per 30 days becomes 7.2 times (= 30 × 24 / 100).
[0124] Also, when the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 is 10 m 3 / h and the carbon dioxide gas concentration detected by the concentration sensor 160 is 10 ppm, the adsorption rate of carbon dioxide gas in the adsorption towers 300A and 300B is 0.1 m 3 / h (= 10 × 1000 × 10 × 10 -6 ) It becomes. Also, the switching interval of the connection states S1 and S2 becomes 50 h (= 5 / 0.1). Further, the switching frequency of the connection states S1 and S2 per 30 days becomes 14.4 times (= 30 × 24 / 50).
[0125] Also, when the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 is 10 m 3 / h and the carbon dioxide gas concentration detected by the concentration sensor 160 is 25 ppm, the adsorption rate of carbon dioxide gas in the adsorption towers 300A and 300B is 0.25 m 3 / h (= 10 × 1000 × 25 × 10 -6 ) It becomes. Also, the switching interval of the connection states S1 and S2 becomes 20 h (= 5 / 0.25). Further, the switching frequency of the connection states S1 and S2 per 30 days becomes 36 times (= 30 × 24 / 20).
[0126] As described above, when the connection states S1 and S2 of the adsorption separation device 300 are switched based on the total amount of carbon dioxide gas sent into the adsorption separation device 300, there is no need to switch the connection states S1 and S2 based on the flow rate of carbon dioxide gas on the premise of the maximum guaranteed value. As a result, the adsorption capacity of the adsorbent can be fully utilized, and the switching frequency of the connection states S1 and S2 can be further reduced.
[0127] <I. Modification Example 2>
[0128] (I1. Outline) Next, a refining device 100 according to the second modification will be described.
[0129] The purification apparatus 100 according to the above-mentioned first modification switches the connection states S1, S2 of the adsorption separation apparatus 300 based on the flow rate of high-purity oxygen gas detected by the flow rate sensor 150 and the concentration of carbon dioxide gas detected by the concentration sensor 160. In contrast, the purification apparatus 100 according to this modification switches the connection states S1, S2 of the adsorption separation apparatus 300 using not only the flow rate of high-purity oxygen gas and the concentration of carbon dioxide gas, but also the internal pressure of the piping in the adsorption separation apparatus 300.
[0130] Other aspects of the refining device 100, such as the hardware configuration, are as described above, and therefore will not be described repeatedly.
[0131] (I2. Pressure Sensor 170) The pressure sensor 170 will be described with reference to Fig. 13. Fig. 13 is a diagram showing a pipe connection state S1 of the adsorption / separation device 300.
[0132] The adsorption separation apparatus 300 shown in Fig. 13 differs from the adsorption separation apparatus 300 shown in Fig. 5 in that it includes a pressure sensor 170. The configuration other than the pressure sensor 170 is as described in Fig. 5, and therefore description thereof will not be repeated.
[0133] The pressure sensor 170 detects the internal pressure of the piping in the adsorption / separation device 300. The type of the pressure sensor 170 is not particularly limited. As an example, the pressure sensor 170 is a resistance film type pressure gauge. Alternatively, the pressure sensor 170 may be a capacitance type pressure gauge. Alternatively, the pressure sensor 170 may be an optical type pressure gauge.
[0134] The pressure sensor 170 may be installed at any position on the piping inside the adsorption separation apparatus 300. In the example of Fig. 13, the pressure sensor 170 is installed downstream of the adsorption towers 300A and 300B in the direction of the airflow of high-purity oxygen gas passing through the adsorption separation apparatus 300. In other words, the pressure sensor 170 is installed on the piping near the outlet of the ultra-high purity oxygen gas produced by the adsorption separation apparatus 300.
[0135] The maximum amount of carbon dioxide gas adsorbed in the adsorption towers 300A and 300B varies depending on the pressure inside the adsorption towers 300A and 300B.
[0136] More specifically, when the pressure in the adsorption towers 300A, 300B increases, the volume of the high-purity oxygen gas in the adsorption towers 300A, 300B decreases. As a result, the speed at which the high-purity oxygen gas passes through the adsorption towers 300A, 300B (hereinafter also referred to as the "intra-cylinder moving speed") decreases, and the time required for the high-purity oxygen gas to pass through the adsorption towers 300A, 300B increases. As a result, the adsorption capacity of the adsorption towers 300A, 300B is gradually used up, starting from the adsorbent on the inlet side. That is, in this case, the amount of carbon dioxide gas adsorbed by the adsorption towers 300A, 300B increases.
[0137] On the other hand, if the pressure in the adsorption towers 300A, 300B is lowered, the volume of the high-purity oxygen gas in the adsorption towers 300A, 300B becomes larger. As a result, the moving speed of the high-purity oxygen gas in the cylinder increases, and the time required for the high-purity oxygen gas to pass through the adsorption towers 300A, 300B becomes shorter. As a result, the carbon dioxide gas contained in the high-purity oxygen gas reaches the outlet of the adsorption towers 300A, 300B before being sufficiently adsorbed in the adsorption towers 300A, 300B sooner. In this case, it is necessary to replace the adsorbent before the adsorption capacity of the adsorption towers 300A, 300B is fully used up. That is, in this case, the carbon dioxide gas from the adsorption towers 300A, 300B becomes less.
[0138] As described above, the maximum adsorption amount of carbon dioxide gas in the adsorption towers 300A and 300B varies according to the pressure inside the adsorption towers 300A and 300B. Therefore, the control unit 50 reduces the switching frequency of the connection states S1 and S2 as the internal pressure detected by the pressure sensor 170 is higher. In other words, the control unit 50 increases the switching frequency of the connection states S1 and S2 as the internal pressure detected by the pressure sensor 170 is lower.
[0139] More specifically, the control unit 50 determines the switching interval of the connection states S1 and S2 based on a predetermined calculation formula. The calculation formula uses at least one of the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150, the concentration of the carbon dioxide gas detected by the concentration sensor 160, and the internal pressure detected by the pressure sensor 170 as an explanatory variable, and the switching interval of the connection states S1 and S2 as the objective variable.
[0140] The above calculation formula is defined such that the switching interval of the connection states S1 and S2 becomes longer as the flow rate of the high-purity oxygen gas detected by the flow rate sensor 150 is lower. Also, the above calculation formula is defined such that the switching interval of the connection states S1 and S2 becomes longer as the concentration of the carbon dioxide gas detected by the concentration sensor 160 is lower. Furthermore, the above calculation formula is defined such that the switching interval of the connection states S1 and S2 becomes longer as the internal pressure detected by the pressure sensor 170 is higher.
[0141] <J. Others> In this way, by using the purification device 100 disclosed above, the adsorbent can be effectively utilized, and unnecessary adsorption and desorption operations do not need to be performed. Therefore, the driving energy can be reduced, and it can contribute to some activities of the sustainable development goals (SDGs).
[0142] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included. [Explanation of symbols]
[0143] 10 cryogenic separation device, 12 filter, 14 compressor, 18 adsorber, 20 heat exchanger, 22 fractionator, 22A lower tower, 22B upper tower, 50 control unit, 100 purification device, 101 control circuit, 102 ROM, 103 RAM, 104 communication interface, 110 bus, 120 auxiliary storage device, 122 control program, 140 removal mechanism, 150 flow sensor, 152 heat exchanger, 154 heater, 160 concentration sensor, 170 pressure sensor, 200 catalyst cylinder, 202 cooler, 300 adsorption separation device, 300A adsorption tower, 300B adsorption tower, F10 piping, F20 piping, P2 branch point, S1 connection state, S2 connection state, SM1 simulation, SM2 simulation, SMX simulation, V1 valve, V2 valve, V3 Valve, V4 Valve, V5 Valve, V6 Valve, V7 Valve, V8 Valve.
Claims
1. A purification device for increasing the purity of raw oxygen gas produced by an oxygen production device, comprising: The raw material oxygen gas contains hydrocarbons and carbon dioxide gas, a catalyst cylinder having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide; a first adsorption tower and a second adsorption tower capable of adsorbing carbon dioxide gas from the raw oxygen gas that has passed through the catalyst tube; a flow rate sensor for detecting a flow rate of the raw material oxygen gas before the raw material oxygen gas is fed into the first and second adsorption towers; a control unit capable of alternately switching a connection state of pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide gas while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide gas while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed, The control unit is configured to reduce the frequency of switching the connection state as the flow rate decreases.
2. 2. The refining apparatus according to claim 1, wherein the flow rate sensor is disposed upstream of the catalyst cylinder in a direction of an airflow of the raw oxygen gas passing through the catalyst cylinder.
3. The refining device according to claim 1 , wherein the refining device switches the connection state every time an integrated amount of the flow rate reaches a predetermined amount.
4. the purification apparatus further includes a concentration sensor for detecting a concentration of carbon dioxide gas contained in the raw oxygen gas after the raw oxygen gas has passed through the catalyst tube and before the raw oxygen gas is fed into the first and second adsorption towers, The refining apparatus according to claim 1 , wherein the control unit reduces the switching frequency as the concentration decreases.
5. The refining apparatus further includes a pressure sensor for detecting an internal pressure of the pipe, The refining apparatus according to claim 1 , wherein the control unit reduces the switching frequency as the internal pressure increases.
6. 3. The refining apparatus according to claim 1, wherein a concentration of oxygen gas contained in the raw oxygen gas before passing through the catalyst column is 99.5% or more.
7. The refinery apparatus according to claim 1 or 2, wherein the catalyst comprises a precious metal.
8. A method for controlling a purification device for increasing the purity of raw oxygen gas produced by an oxygen production device, comprising the steps of: The raw material oxygen gas contains hydrocarbons and carbon dioxide gas, The refining apparatus comprises: a catalyst cylinder having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide; a first adsorption tower and a second adsorption tower capable of adsorbing carbon dioxide gas from the raw oxygen gas that has passed through the catalyst tube; a flow rate sensor for detecting a flow rate of the raw oxygen gas before the raw oxygen gas is fed to the first and second adsorption towers, The control method includes: obtaining the flow rate from the flow sensor; a step of alternately switching a connection state of pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide gas while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide gas while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed, The method of claim 1, wherein the lower the flow rate, the less frequently the switching step is performed.
9. A control program for a purification device for increasing the purity of raw oxygen gas produced by an oxygen production device, comprising: The raw material oxygen gas contains hydrocarbons and carbon dioxide gas, The refining apparatus comprises: a catalyst cylinder having a catalyst for converting the hydrocarbons contained in the raw oxygen gas into carbon dioxide; a first adsorption tower and a second adsorption tower capable of adsorbing carbon dioxide gas from the raw oxygen gas that has passed through the catalyst tube; a flow rate sensor for detecting a flow rate of the raw oxygen gas before the raw oxygen gas is fed to the first and second adsorption towers, The control program causes the refining apparatus to obtaining the flow rate from the flow sensor; a step of alternately switching a connection state of pipes communicating with the first and second adsorption towers between a state in which the first adsorption tower adsorbs carbon dioxide gas while the second adsorption tower desorbs the carbon dioxide gas previously adsorbed, and a state in which the second adsorption tower adsorbs carbon dioxide gas while the first adsorption tower desorbs the carbon dioxide gas previously adsorbed, The smaller the flow rate, the less frequently the switching step is executed.
Citation Information
Patent Citations
Pre-treatment device for air separation apparatus and pre-treatment method therefor
JP2014113594A