Gas purification device and method for operating same

Abstract

The invention provides a gas purification device and a method for operating the gas purification device, wherein the amount of energy required by a gas heater can be reduced and the operation cost can be reduced. This gas purification device is provided with: a gas heater for heating a gas to be purified; a catalyst cartridge for catalytically reacting impurity components in the heated gas to be purified; a refiner for removing a component to be removed from the gas to be refined, which is led out from the catalyst cartridge; a gas introduction path for introducing a gas to be purified into the gas heater; and a gas introduction valve. A refiner inlet path through which the gas led out from the catalyst cartridge is introduced into the refiner; a bypass path branched from the upstream side of the gas introduction valve and connected to the refiner inlet path; and an analyzer that is provided upstream of the branch section of the bypass path, measures the concentration of an impurity component in the gas to be purified, and controls the opening and closing of the gas introduction valve and the bypass valve on the basis of the measured concentration of the impurity component.

Description

[0001] This application is a divisional application of application number 202010037226.4, filed on January 14, 2020, entitled "Gas Purification Apparatus and Operating Method Thereof". Technical Field

[0002] The present invention relates to a gas purification apparatus and a method of operation thereof, and more specifically, to a gas purification apparatus and a method of operation thereof having a heater for heating a gas to be purified introduced into a catalytic reactor to a predetermined catalytic reaction temperature, wherein the catalytic reactor causes impurity components in the gas to undergo a catalytic reaction. Background Technology

[0003] As a device for refining gas by removing impurities, a gas refining apparatus is known that combines a catalyst cartridge filled with a catalyst and an adsorption cartridge filled with an adsorbent (see, for example, Patent Document 1). For instance, when removing hydrocarbons as impurities from nitrogen gas, the target gas for refining, nitrogen gas heated by a heater is introduced into the catalyst cartridge. After methane is decomposed into water and carbon dioxide through a catalytic reaction, the generated water and carbon dioxide are adsorbed and removed by the adsorption cartridge, thereby obtaining refined nitrogen gas.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2012-51753 Summary of the Invention

[0005] The problem the invention aims to solve

[0006] However, in conventional gas purification apparatuses utilizing catalyst cartridges, a heater must be installed upstream (front section) of the catalyst cartridge to bring the target gas into contact with the catalyst at high temperatures. This heater heats the target gas introduced into the catalyst cartridge to the temperature required for the catalytic reaction. Therefore, the energy required to heat the target gas becomes very large, especially in semiconductor manufacturing equipment that uses large quantities of purified gas, significantly impacting operating costs.

[0007] Therefore, the object of the present invention is to provide a gas purification apparatus and its operation method that can suppress the energy required by the gas heater, thereby reducing operating costs.

[0008] Solution for solving the problem

[0009] To achieve the aforementioned objective, the gas purification apparatus of the present invention comprises: a gas heater for heating the gas to be purified; a catalyst cartridge for catalytically reacting impurity components in the gas to be purified heated by the gas heater to become components to be removed; and a purifier for removing the components to be removed from the gas to be purified discharged from the catalyst cartridge. The gas purification apparatus is characterized by having: a gas inlet path and a gas inlet valve disposed on the gas inlet path, through which the gas to be purified is introduced into the gas heater; and a purifier inlet path, which receives the gas from the gas heater. The gas exiting the catalyst cartridge is introduced into the purifier; a purifier outlet path exits the purified gas purified by the purifier; a bypass path and a bypass valve located on the bypass path, the bypass path branching upstream of the gas inlet valve and connecting to the purifier inlet path or the purifier outlet path; and an analyzer located upstream of the branch of the bypass path to measure the concentration of impurity components in the purified target gas flowing in the gas inlet path, and to control the opening and closing of the gas inlet valve and the bypass valve based on the measured concentration of impurity components.

[0010] Furthermore, the gas purification apparatus of the present invention is characterized in that the gas inlet valve has a detour path connecting the upstream side and the downstream side of the gas inlet valve, and the detour path has a flow regulating valve for regulating the flow rate of the gas flowing in the detour path.

[0011] Furthermore, in the operation method of the gas purification apparatus of the present invention, the gas purification apparatus includes: a gas heater for heating the gas to be purified; a catalyst cartridge for catalytically reacting impurity components in the gas to be purified heated by the gas heater to become components to be removed; and a purifier for removing the components to be removed from the gas to be purified discharged from the catalyst cartridge. The gas purification apparatus also includes: a gas inlet path and a gas inlet valve provided in the gas inlet path for introducing the gas to be purified into the gas heater; a purifier inlet path for introducing gas discharged from the catalyst cartridge into the purifier; a purifier outlet path for discharging the purified gas purified by the purifier; a bypass path and a bypass valve provided in the bypass path, the bypass path branching from the upstream side of the gas inlet valve and connecting to the purifier inlet. The gas purification apparatus is characterized by the following operation method: when the impurity concentration measured by the analyzer is higher than a preset concentration, the gas is introduced into the gas heater via the gas inlet path by closing the bypass valve and opening the gas inlet valve; when the impurity concentration measured by the analyzer is lower than a preset concentration, the gas is introduced into the gas heater via the gas inlet path by closing the bypass valve and opening the gas inlet valve; and when the impurity concentration measured by the analyzer is lower than a preset concentration, the gas is introduced into the gas heater via the bypass path by closing the gas inlet valve and opening the bypass valve, instead of being introduced into the gas heater.

[0012] Furthermore, the operation method of the gas purification apparatus of the present invention is characterized in that, when the gas inlet valve is closed, the gas to be purified at a predetermined flow rate is introduced into the gas heater.

[0013] The effects of the invention

[0014] According to the present invention, when the concentration of impurity components measured by the analyzer is lower than a preset concentration, the gas to be purified can be prevented from being introduced into the heater, thus eliminating the need for energy to heat the gas to be purified using a heater. This allows for a reduction in the operating cost of the gas purification apparatus. Attached Figure Description

[0015] Figure 1 This is a system diagram illustrating one embodiment of the gas purification apparatus of the present invention.

[0016] Figure 2This is a system diagram of the gas purification apparatus used in the experimental example.

[0017] Explanation of reference numerals in the attached figures

[0018] 11. Feed gas supply path; 12. Catalyst cartridge; 13. Purifier; 14. Heat exchanger; 15. Gas heater; 16. Gas inlet path; 17. Bypass path; 18. Gas inlet valve; 19. Bypass valve; 20. Purifier inlet path; 21. Analyzer; 22. Detour path; 23. Flow control valve; 24. Flow meter; 31. Methane inlet section; 32. Purifier outlet path; 33. Flow meter; 34. Outlet gas flow control valve; 35. Analyzer. Detailed Implementation

[0019] Figure 1 This is a system diagram illustrating one embodiment of the gas purification apparatus of the present invention. The gas purification apparatus shown in this embodiment purifies the raw material gas by converting the target component (impurity component) contained in the raw material gas (purification target gas) supplied from the raw material gas supply path 11 into a component that can be removed by the purifier 13 through a catalytic reaction in the catalyst cylinder 12, and then removing the target component by the purifier 13. A heat exchanger 14 is provided upstream of the catalyst cylinder 12 to perform heat recovery by exchanging heat between the high-temperature gas after the catalytic reaction exiting from the catalyst cylinder 12 and the raw material gas, and a gas heater 15 to heat the raw material gas to the temperature required for the catalytic reaction.

[0020] The catalyst cartridge 12 has a heater and an insulation layer (neither shown). Therefore, the heater of the catalyst cartridge 12 is not intended to heat the catalyst inside the cartridge, but rather is provided to prevent the catalyst's temperature from dropping, together with the insulation layer. The catalyst undergoes a catalytic reaction by contacting the high-temperature feed gas heated by the heat exchanger 14 and the gas heater 15. Therefore, the gas heater 15 is equipped with a capacity capable of heating all the feed gas supplied from the feed gas supply path 11 to a predetermined catalytic reaction temperature. The heater output is automatically controlled based on the measured temperature of a thermometer (not shown) located at the outlet of the gas heater 15 or the inlet of the catalyst cartridge 12.

[0021] The raw material gas supply path 11 branches into a gas inlet path 16 and a bypass path 17. The gas inlet path 16 is the path that introduces raw material gas into the catalyst cylinder 12 via the gas inlet valve 18, the heat exchanger 14, and the gas heater 15. The bypass path 17, which bypasses the catalyst cylinder 12, etc., is connected to the purifier inlet path 20, which is provided on the inlet side of the purifier 13, via the bypass valve 19.

[0022] Furthermore, an analyzer 21 is installed upstream of the branch of the bypass path 17 in the raw material gas supply path 11. This analyzer is capable of controlling the opening and closing of the gas inlet valve 18 and the bypass valve 19 while measuring the concentration of impurities contained in the raw material gas flowing within the raw material gas supply path 11. The analyzer 21 has a valve opening and closing control unit that closes the bypass valve 19 and opens the gas inlet valve 18 when the measured impurity concentration is higher than a preset concentration, and closes the gas inlet valve 18 and opens the bypass valve 19 when the measured impurity concentration is lower than a preset concentration.

[0023] Additionally, a detour path 22 connecting the upstream and downstream sides of the gas inlet valve 18 is provided in the gas inlet path 16. A flow regulating valve 23 for adjusting the gas flow rate in the detour path 22 and a flow meter 24 for confirming the flow rate are provided on the detour path 22. This detour path 22 is used to introduce a portion of the raw material gas into the catalyst container 12 via the heat exchanger 14 and the gas heater 15 when the gas inlet valve 18 is fully closed. By introducing a portion of the raw material gas heated by the heat exchanger 14 and the gas heater 15 into the catalyst container 12, the catalyst inside the catalyst container 12 is heated and maintained at a predetermined catalytic reaction temperature.

[0024] In this gas purification apparatus, when the concentration of impurities in the raw material gas measured by analyzer 21 is higher than a set concentration, the bypass valve 19 is closed and the gas inlet valve 18 is opened, allowing all the raw material gas to be introduced into the heat exchanger 14 through the gas inlet path 16 for initial heating. Then, the entire raw material gas is reheated using the gas heater 15 to a predetermined catalytic reaction temperature, and then introduced into the catalyst cylinder 12 at a high temperature. Through catalytic reaction, the impurities in the raw material gas are converted into components that can be removed by the purifier 13 (the components to be removed). The high-temperature raw material gas containing the components to be removed is cooled by heat recovery in the heat exchanger 14, and then introduced into the purifier 13 through the purifier inlet path 20. The components to be removed are removed using adsorbents or the like in the purifier 13, resulting in a purified gas from which the components to be removed have been removed from the raw material gas.

[0025] The purifier 13 can employ a device corresponding to the component to be removed. Typically, it can utilize a temperature swing adsorption separation device (TSA device) or a pressure swing adsorption separation device (PSA device) that uses an adsorbent. In the case of the aforementioned TSA device or PSA device, by configuring multiple adsorption cylinders and sequentially switching between the adsorption step and the regeneration step, the target component from the feed gas can be continuously adsorbed and removed.

[0026] On the other hand, when the concentration of impurity components measured by analyzer 21 is lower than the set concentration, the gas inlet valve 18 is closed and the bypass valve 19 is opened, allowing the raw material gas to be introduced from the bypass path 17 to the purifier inlet path 20, directly into the purifier 13. That is, it is not necessary to use the gas heater 15 to heat the raw material gas, so the energy required for heating the raw material gas by the gas heater 15 is not needed, thus reducing power consumption.

[0027] At this time, after a suitable amount of raw material gas is heated by the heat exchanger 14 and the gas heater 15 via the flow regulating valve 23 of the bypass path 22, it is introduced into the catalyst cylinder 12. This allows the catalyst in the catalyst cylinder 12 to be heated to a predetermined catalytic reaction temperature using the pre-heated raw material gas, preventing the catalyst temperature from dropping. Even in this case, compared to heating all the raw material gas using the gas heater 15, the amount of raw material gas heated by the gas heater 15 is less, thus significantly reducing the amount of raw material gas heated in the gas heater 15 and reducing the energy required for heating the raw material gas. Therefore, when the concentration of impurities in the raw material gas increases, causing the raw material gas path to switch from the bypass path 17 to the gas introduction path 16, the catalytic reaction in the catalyst cylinder 12 can begin immediately, preventing unreacted impurities from flowing out of the catalyst cylinder 12 at a high concentration.

[0028] Alternatively, instead of connecting the downstream of the bypass path 17 to the inlet path 20 of the purifier, it can be connected to the path located on the outlet side of the purifier 13. When the concentration of impurities in the raw material gas measured by the analyzer 21 is low, the raw material gas flows from the bypass path to the outlet side of the purifier 13. Alternatively, the gas inlet valve 18 and the bypass valve 19 can be flow-regulating valves. When the concentration of impurities in the raw material gas measured by the analyzer 21 is equal to or slightly higher than a set concentration, the flow rate of the raw material gas flowing into the gas inlet path 16 and the flow rate of the gas flowing into the bypass path 17 can be adjusted so that the raw material gas flows into both paths simultaneously in an appropriate ratio. This allows for the reduction of energy required for heating the raw material gas while maintaining the purity of the gas exiting the purifier.

[0029] For example, in the process of refining nitrogen to obtain high-purity nitrogen with a methane content of less than 10 ppb by removing methane from nitrogen gas, the raw nitrogen gas is heated to approximately 200°C to 400°C by passing it through a heat exchanger 14 and a gas heater 15, and then introduced into a catalyst cartridge 12. There, it comes into contact with an oxidation catalyst filled within the cartridge 12, and the methane is decomposed into water and carbon dioxide through an oxidation reaction at high temperature. The water and carbon dioxide generated by the catalytic reaction, along with the target components already present in the raw nitrogen gas, are removed by the adsorbent, such as alumina or molecular sieve, in the adsorption cartridge of the refiner 13. Thus, high-purity nitrogen with a methane content of less than 10 ppb can be obtained.

[0030] At this point, since the methane concentration in the raw nitrogen gas is initially below 10 ppb, there is no need to convert methane into water and carbon dioxide through a catalytic reaction. It can be directly used as high-purity nitrogen gas. Therefore, there is no need to heat the raw nitrogen gas and introduce it into the catalyst cylinder 12. Thus, by using the bypass path 17, the raw nitrogen gas is directed downstream of the catalyst cylinder 12 without passing through the gas heater 15 and the catalyst cylinder 12, thereby reducing the energy consumption of the gas heater 15.

[0031] Next, instructions on using Figure 2 The results of experiments conducted using the gas purification apparatus shown to confirm the effectiveness of the present invention are presented. Furthermore, in the following description, the same reference numerals are used to denote components identical to those in the gas purification apparatus shown in the embodiment, and detailed descriptions are omitted.

[0032] The target gas for purification is nitrogen, intended for semiconductor manufacturing equipment, while the impurity component is methane, a type of hydrocarbon. For example... Figure 2 As shown, for the experimental purification apparatus, a methane inlet 31 for introducing methane is provided on the upstream side of the analyzer 21. A flow meter 33 and an outlet gas flow regulating valve 34 are provided on the purification outlet path 32 provided on the outlet side of the purifier 13. An analyzer 35 identical to that on the supply side is provided to measure the concentration of methane.

[0033] A Pd-based catalyst is filled into the catalyst cartridge 12, and the surface temperature is automatically maintained at 300°C using a heater located in the catalyst cartridge 12. Additionally, the gas heater 15 is automatically controlled to maintain the gas temperature at the heater outlet at 300°C. To prevent burns and excessive power consumption due to heat dissipation, the catalyst cartridge 12, the gas heater 15, and the piping for the high-temperature gas flow are surrounded by a 100mm thick insulation material. Furthermore, molecular sieves and alumina are layered and filled in the purifier 13 to remove carbon dioxide and moisture, which are the target components generated by the catalytic reaction in the catalyst cartridge 12.

[0034] First, as a previous example, with the bypass valve 19 closed, the gas inlet valve 18 is opened, and the gas flow rate is adjusted to 20 Nm under standard conditions via the outlet gas flow regulating valve 34 located at the device outlet. 3 / h. At this time, the nitrogen supply pressure from the raw material gas supply path 11 is 0.8 MPaG. All the supplied nitrogen is heated to 300°C using the gas heater 15. Under this condition, the catalyst inlet cartridge 12 is operated for 3 hours, and the power consumption is measured. The result is a power consumption of 4 kW.

[0035] On the other hand, as an experimental example of the method of the present invention, except that nitrogen gas with a methane content of less than 10 ppb was used, the flow rate and pressure of the nitrogen gas and the temperature of the catalyst cartridge 12 were operated in the same manner as in the comparative example. Furthermore, with the gas inlet valve 18 closed, the flow regulating valve 23 was adjusted to ensure that the amount of nitrogen gas flowing in the bypass path 22 was 1 L / min, so that even with the gas inlet valve 18 closed, a certain amount of nitrogen gas flowed toward the gas heater 15. The gas inlet valve 18 and the bypass valve 19 were set to switch on and off such that the set concentration of the analyzer 21 was set to 10 ppb.

[0036] Initially, the system operates without adding methane from the methane inlet 31. At this time, the methane concentration measured by the analyzer 21 is below 10 ppb, so the gas inlet valve 18 is closed and the bypass valve 19 is opened. The approximate total amount of nitrogen supplied passes through the bypass path 17, resulting in a nitrogen flow rate of 1 L / min in the gas heater 15. The methane concentration measured by the analyzer 35, located at the purifier outlet path 32, is also below 10 ppb.

[0037] After one hour, methane is added at a rate of 1 sccm from the methane inlet 31 to bring the methane concentration in the nitrogen to 3 ppm. At this point, the methane concentration measured in the analyzer 21 exceeds the set concentration by 10 ppb, so the bypass valve 19 automatically closes and the gas inlet valve 18 opens, allowing all the nitrogen gas with added methane to flow into the gas inlet path 16. This results in a state where methane is converted into carbon dioxide and water through a catalytic reaction in the catalyst cartridge 12, and the generated carbon dioxide and water are adsorbed and removed in the purifier 13. In this state, the methane concentration measured by the analyzer 35 at the purifier outlet path 32 is below 10 ppb, confirming that methane, as an impurity component, has been reliably removed.

[0038] After one hour, when methane addition was stopped, the methane concentration in analyzer 21 fell below the set concentration by 10 ppb, thus automatically switching to a closed gas inlet valve 18 and an open bypass valve 19. This resulted in a nitrogen flow rate of 1 L / min in gas heater 15. The system operated in this state for one hour, and the total power consumption for three hours (including one hour of methane addition) was measured. The result was a power consumption of 1.5 kW.

[0039] Therefore, compared to the past, power consumption can be reduced to 1 / 2.7. In addition, the amount of power consumption that can be reduced varies depending on conditions such as the flow rate of nitrogen flowing to the gas heater 15 through the flow regulating valve 23 when the gas inlet valve 18 is closed. For example, the power consumption reduction effect also varies depending on the flow rate or purity of the nitrogen used as raw material and the set concentration of the analyzer 21 used to switch the opening and closing of the gas inlet valve 18 and the bypass valve 19.

[0040] Furthermore, by using a valve with adjustable opening as the gas inlet valve 18, even without using the bypass path 22 or the flow control valve 23, a portion of the raw material gas can flow into the gas inlet path 16 while the gas inlet valve 18 is closed, allowing the gas inlet valve 18 to be slightly open. Additionally, it is preferable that, even when the concentration of impurity components changes drastically, the analyzer 21 is positioned as close as possible upstream of the supply source in the raw material gas supply path 11 to reliably switch the opening and closing of the gas inlet valve 18 and the bypass valve 19.

Claims

1. A gas refining apparatus, wherein the gas refining apparatus has: a gas heater that heats a refining target gas to a temperature required for a catalytic reaction; a catalyst cartridge that has a heater, and causes a catalytic reaction of an impurity component in the refining target gas heated to a catalytic reaction temperature by the gas heater to become a removal target component; a refiner that removes the removal target component in the refining target gas led out from the catalyst cartridge; and a heat exchanger that exchanges heat between a gas after the catalytic reaction led out from the catalyst cartridge and the refining target gas, the gas refining apparatus is characterized by having: a gas introduction path and a gas introduction valve provided in the gas introduction path, through which the refining target gas is introduced to the gas heater; a refiner inlet path that introduces the gas led out from the catalyst cartridge to the refiner; a refiner outlet path that leads out a refined gas refined by the refiner; a bypass path and a bypass valve provided in the bypass path, the bypass path being branched from an upstream side of the gas introduction valve and being connected to the refiner inlet path or the refiner outlet path; and an analyzer that is provided at a position upstream of a branching portion of the bypass path, measures a concentration of an impurity component in the refining target gas flowing in the gas introduction path, and controls opening and closing of the gas introduction valve and the bypass valve based on the measured concentration of the impurity component, the heat exchanger, the gas heater, and the catalyst cartridge are arranged in this order on the gas introduction path, the analyzer controls to close the bypass valve and open the gas introduction valve when the concentration of the impurity component measured by the analyzer is higher than a set concentration set in advance, and controls to close the gas introduction valve and open the bypass valve when the concentration of the impurity component measured by the analyzer is lower than the set concentration set in advance, the gas introduction valve has a detour path that connects an upstream side and a downstream side of the gas introduction valve, the detour path being located on the upstream side of the heat exchanger, and has a flow rate adjusting valve that adjusts a flow rate of a gas flowing in the detour path in a state where the gas introduction valve is closed, a predetermined amount of the refining target gas is introduced to the catalyst cartridge after passing through the heat exchanger and the gas heater by the flow rate adjusting valve, so that a catalyst in the catalyst cartridge is heated to a predetermined catalytic reaction temperature.

2. A method of operating a gas refining apparatus, wherein the gas refining apparatus has: a gas heater that heats a refining target gas to a temperature required for a catalytic reaction; a catalyst cartridge that has a heater, and causes a catalytic reaction of an impurity component in the refining target gas heated to a catalytic reaction temperature by the gas heater to become a removal target component; a refiner that removes the removal target component in the refining target gas led out from the catalyst cartridge; and a heat exchanger that exchanges heat between a gas after the catalytic reaction led out from the catalyst cartridge and the refining target gas, and the gas refining apparatus has: ​ ​ a gas introduction path through which the gas heater is introduced with the gas to be refined, and a gas introduction valve provided in the gas introduction path; a refiner inlet path through which the gas introduced from the catalyst cartridge is introduced to the refiner; a refiner outlet path through which the refined gas refined by the refiner is discharged; a bypass path branched from an upstream side of the gas introduction valve and connected to the refiner inlet path or the refiner outlet path, and a bypass valve provided in the bypass path; and an analyzer provided at a position upstream of the branch of the bypass path, which measures the concentration of an impurity component in the gas to be refined flowing in the gas introduction path, and which controls the opening and closing of the gas introduction valve and the bypass valve based on the measured concentration of the impurity component, the gas refining device in which the heat exchanger, the gas heater, and the catalyst cartridge are arranged in this order on the gas introduction path, the operation method of the gas refining device being characterized in that, when the concentration of the impurity component measured by the analyzer is higher than a set concentration set in advance, the gas to be refined is introduced to the gas heater through the gas introduction path by closing the bypass valve and opening the gas introduction valve, and when the concentration of the impurity component measured by the analyzer is lower than the set concentration set in advance, the gas to be refined is not introduced to the gas heater but is introduced to the refiner inlet path or the refiner outlet path through the bypass path by closing the gas introduction valve and opening the bypass valve, when the gas introduction valve is closed, the gas to be refined at a flow rate set in advance is introduced to the catalyst cartridge after passing through the heat exchanger and the gas heater, thereby heating the catalyst in the catalyst cartridge to a predetermined catalytic reaction temperature.

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