Hydrogen recovery system and method

Abstract

An embodiment of the invention relates to a hydrogen recovery system (1) for extracting hydrogen from a process gas. The hydrogen recovery system (1) may include an electrochemical pump (11) for extracting at least a portion of hydrogen generated in the process gas. The electrochemical pump (11) has an anode compartment (13) having at least one anode (14), a cathode compartment (15) having at least one cathode (16), and a membrane (17) disposed between the anode compartment (13) and the cathode compartment (15). A controller (59) is provided for controlling the current supplied to the electrochemical pump (11). The anode compartment (13) has an anode compartment inlet (23) for introducing process gas into the anode compartment (13) and an anode compartment outlet (25) for discharging waste gas from the anode compartment (13). The cathode compartment (15) has a cathode compartment outlet (27) for discharging hydrogen extracted from the process gas.

Description

Technical Field

[0001] The present disclosure relates to hydrogen recovery systems and methods. The hydrogen recovery system can be configured to remove at least a portion of the hydrogen present in the process gas. Aspects of the present invention relate to vacuum systems, electrochemical pumps, and methods for recovering hydrogen from process gases.

Background Art

[0002] Vacuum systems and abatement systems often include a vacuum pump that exhausts the process gas at atmospheric pressure during use. The vacuum pump can be, for example, a dry pump. The operation of a vacuum pump for exhausting a process gas at atmospheric pressure may require high power consumption. This is particularly relevant for vacuum systems that require pumping large amounts of gas. For example, in a vacuum system for extreme ultraviolet (EUV) lithography, pumping large amounts of hydrogen may be required. Hydrogen is typically exhausted at atmospheric pressure and diluted with atmospheric air.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to address one or more of the drawbacks associated with the prior art.

Means for Solving the Problems

[0004] Aspects and embodiments of the present invention provide a hydrogen recovery system, a vacuum system, an electrochemical pump, and a method for recovering hydrogen from a process gas, as described in the appended claims.

[0005] According to one aspect of the present invention, a vacuum system according to claim 1 is provided.

[0006] According to the present invention, the process gas is supplied at near-atmospheric pressure. The hydrogen recovery system is used in combination with a vacuum system. The process gas from the vacuum system is supplied to the hydrogen recovery system. The process gas is exhausted to the hydrogen recovery system at a pressure below atmospheric pressure. By exhausting the process gas at near-atmospheric pressure, the power consumption of the vacuum system can be reduced. It is believed that power savings of more than 50% can be achieved when operating the dry pump of the vacuum system. In addition, in hydrogen systems such as extreme ultraviolet (EUV) systems, the need for nitrogen purge gas can be reduced or eliminated. The process gas can be supplied to the hydrogen recovery system at a pressure of 700 mbar, 600 mbar, 500 mbar, 400 mbar, 300 mbar, or 200 mbar or less.

[0007] By connecting an electrochemical pump to the exhaust port of the EUV dry pump, the exhaust pressure of the vacuum pump can be reduced, enabling more efficient pumping of hydrogen at, for example, an exhaust output of approximately 200 mbar. In at least certain embodiments, this can reduce power consumption and / or eliminate the need to perform nitrogen purging. The electrochemical pump can function as the final stage and can operate to further compress the hydrogen to atmospheric pressure or above. The hydrogen recovered by the hydrogen recovery system can be recycled to the customer's hydrogen network as needed. The hydrogen recovery system may include a dryer to dry the recovered hydrogen gas before use in the vacuum system.

[0008] The process gas may include a mixed gas. The process gas contains hydrogen mixed with one or more other gases. During use, the hydrogen recovery system operates to remove at least a portion of the hydrogen from the process gas. The hydrogen removed from the process gas can be reused, for example, in an industrial process. The treated process gas can be used as waste gas discharged to a pollution control system. The hydrogen recovery system can remove at least 80% of the hydrogen from the process gas. The process gas can be discharged through a vacuum system. The vacuum system operates to establish a vacuum for an industrial process, for example, related to semiconductor manufacturing. The industrial process could be, for example, extreme ultraviolet (EUV) lithography.

[0009] An electrochemical pump includes an electrochemical hydrogen pump (compressor) for pumping hydrogen through an electrochemical process.

[0010] The control device is configured to control the operation of an electrochemical pump in order to control the recovery of hydrogen from the process gas. The control device can be configured to control the current supplied to the electrochemical pump, for example, by a direct current (DC) power supply. The control device can control the potential difference between at least one anode and at least one cathode. The control device can control the density of the field across the membrane.

[0011] The electrochemical pump can be operated to remove at least some of the hydrogen present in the process gas, thereby reducing the hydrogen content in the process gas. The waste gas collects in the anode compartment. The waste gas has a lower hydrogen content than the process gas supplied to the electrochemical pump. The waste gas can be discharged to a pollution control unit.

[0012] The process gas is supplied at the process gas supply pressure. The process gas supply pressure can be below atmospheric pressure (i.e., less than 1 bar).

[0013] The hydrogen recovery system may be equipped with an inlet pressure sensor for measuring the anode compartment inlet pressure at the anode compartment inlet. The anode compartment inlet pressure may correspond to the process gas supply pressure. The inlet pressure sensor may be configured to output an anode compartment inlet pressure signal indicating the anode compartment inlet pressure to the control unit. Alternatively or additionally, the hydrogen recovery system may be equipped with an outlet pressure sensor for measuring the anode compartment outlet pressure. The outlet pressure sensor may be configured to output an anode compartment outlet pressure signal indicating the anode compartment outlet pressure to the control unit.

[0014] Hydrogen can be discharged from the cathode compartment at the cathode compartment outlet pressure. The cathode compartment outlet pressure can be higher than the anode compartment inlet pressure. The cathode compartment outlet pressure can be higher than atmospheric pressure, for example, higher than 5 bar. The cathode compartment outlet pressure can be 8 bar or higher. In certain embodiments, the cathode compartment outlet pressure can be 10 bar or higher.

[0015] The control unit can be configured to control the operation of the electrochemical pump based on at least one of the anode compartment inlet pressure and the anode compartment outlet pressure. The control unit can use the anode compartment inlet pressure and anode compartment outlet pressure to help prevent the anode of the electrochemical pump from extracting excess hydrogen from the process gas. By controlling the operation of the electrochemical pump, the efficiency of the electrochemical process at the anode can be maintained. The control unit can also be configured to control the operation of the electrochemical pump based on the pressure difference between the anode compartment inlet pressure and the anode compartment outlet pressure. If the pressure difference between the anode compartment inlet pressure and the anode compartment outlet pressure increases beyond a predetermined threshold, the control unit reduces the current and / or voltage supplied to the electrochemical pump. This control helps ensure an adequate supply of hydrogen to at least one anode.

[0016] The control device can be configured to determine the current setpoint and / or voltage setpoint of the electrochemical pump. The current setpoint and / or voltage setpoint can be determined based on at least one of the anode compartment inlet pressure and outlet pressure. The control device can be configured to determine the current setpoint and / or voltage setpoint for the electrochemical pump based on the pressure difference between the anode compartment inlet pressure and the anode compartment outlet pressure.

[0017] The control device can be configured to selectively increase or decrease the current and / or voltage supplied to the electrochemical pump.

[0018] The control device can be configured to control the operation of the electrochemical pump based on the determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is below a predetermined pressure threshold. The control device can be configured to reduce the current and / or voltage supplied to the electrochemical pump based on the determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is below a predetermined pressure threshold. The control device can reduce the current and / or voltage by a predetermined amount or by a predetermined percentage. For example, the current supplied to the electrochemical pump can be reduced by 1% based on the determination that the anode compartment inlet pressure and outlet pressure are below a pressure threshold of 250 mbar.

[0019] The control device can be configured to control the operation of the electrochemical pump based on the determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is greater than a predetermined pressure threshold. The control device can be configured to increase the current and / or voltage supplied to the electrochemical pump based on the determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is greater than a predetermined pressure threshold. The control device can increase the current and / or voltage by a predetermined amount or by a predetermined percentage. For example, the current supplied to the electrochemical pump can be increased by 1% based on the determination that the anode compartment inlet pressure and outlet pressure are higher than a pressure threshold of 250 mbar.

[0020] The control device is described as controlling the operation of the hydrogen recovery system based on one or more measured pressures. Alternatively or additionally, the control device may be configured to control the operation of the hydrogen recovery system based on at least one mass flow rate. For example, the control device may be configured to control the current supplied to the electrochemical pump based on the mass flow rate of hydrogen recovered by the electrochemical pump. Other control techniques are also conceivable.

[0021] The hydrogen recovery system may be equipped with a mass flow meter (MFM) for measuring the mass flow rate of hydrogen from the cathode compartment. The control unit may be configured to determine the current setpoint of the electrochemical pump based on the mass flow rate of hydrogen. The current can be controlled to maintain steady-state operation of the hydrogen recovery system. The base current can be determined in accordance with the two electrons input for one hydrogen molecule output from the electrochemical pump. A supplement (gain) current can be added to the base current to maintain steady-state operation.

[0022] The hydrogen recovery system may include an auxiliary pump that is in fluid communication with the anode compartment outlet. The auxiliary pump can be operated to pump process gas through the anode compartment. The auxiliary pump can be operated to increase the pressure at the anode compartment outlet. The outlet pressure of the auxiliary pump can be higher than the pressure at the anode compartment outlet. The outlet pressure of the auxiliary pump can be approximately atmospheric pressure (1 bar). The control unit can be configured to activate the auxiliary pump when the hydrogen recovery system is started. The control unit can be configured to deactivate the auxiliary pump during steady-state operation of the hydrogen recovery system.

[0023] The hydrogen recovery system may include an auxiliary pump inlet pressure sensor for measuring the inlet pressure of the auxiliary pump. The control unit may be configured to control the operation of the auxiliary pump based on the auxiliary pump inlet pressure. The control unit may be configured to restart the process based on the determination that the auxiliary pump inlet pressure is greater than a predetermined upper threshold. Restarting the hydrogen recovery process may include supplying nitrogen to a vacuum pump located upstream of the hydrogen recovery system.

[0024] The hydrogen recovery system may include a throttle valve for controlling the discharge of exhaust gas from the anode compartment to the auxiliary pump. The control device may be configured to control the throttle valve based on the anode compartment outlet pressure or the auxiliary pump inlet pressure. The control device may be configured to control the throttle valve so as to maintain the exhaust gas pressure at least substantially equal to a predetermined pressure setpoint. The throttle valve may be selectively adjustable to increase or decrease the flow rate of exhaust gas from the anode compartment.

[0025] The hydrogen recovery system may include a supply channel that supplies an inert gas to an auxiliary pump, facilitating the pumping of process gas through the anode compartment.

[0026] The hydrogen recovery system can include at least one valve operable to isolate the auxiliary pump from the anode compartment outlet. The at least one valve can include a first and a second valve in a parallel configuration.

[0027] The control device can be configured to operate the auxiliary pump and selectively open one or more of the at least one valve to purge impurities. The auxiliary pump can be operated to reduce the inlet pressure. The control device can pulse-control the opening of the at least one valve to purge impurities.

[0028] The hydrogen recovery system can include a control (bypass) valve for selectively bypassing the auxiliary pump, and the control device is configured to operate the control valve to bypass the auxiliary pump for the steady operation of the hydrogen recovery system. The control valve can be a three-way valve.

[0029] The steady operation of the hydrogen recovery system can correspond to operation at a predefined pressure or within a predefined pressure range.

[0030] The control device can be configured to output a control signal for controlling the supply of an inert gas. The control device can be configured to output a control signal to prevent the introduction of the inert gas into the vacuum system during the steady operation of the hydrogen recovery system. The inert gas can be, for example, nitrogen. In at least certain embodiments, the amount of nitrogen introduced into the process gas upstream of the hydrogen recovery system can be reduced.

[0031] The hydrogen recovery system can include a flow restrictor operable to control the rate at which gas is discharged from the anode compartment outlet. The flow restrictor enables dead-head operation. [[ID=二十ー]]

[0032] The vacuum pump can be a dry pump. The vacuum system can be an extreme ultraviolet (EUV) system. The EUV system can be operated to perform EUC processes such as EUV lithography.

[0033] A further aspect of the present invention provides a method for recovering hydrogen from a process gas using the electrochemical pump described in claim 16.

[0034] This method may include controlling the current supplied to an electrochemical pump in order to control the recovery of hydrogen from the process gas.

[0035] This method may include controlling the supply of an inert gas to the process gas. This method may also include preventing the introduction of an inert gas into the process gas when the electrochemical pump is operating in a steady state. The inert gas may be, for example, nitrogen. In at least certain embodiments, the amount of nitrogen introduced into the process gas upstream of the hydrogen recovery system can be reduced.

[0036] Any control unit or control device described herein may preferably include a computing device having one or more electronic processors. A system may comprise a single control unit or electronic control device; alternatively, different functions of a control device may be embodied or hosted in different control units or control devices. Where used herein, the terms “control device” or “control unit” should be understood to include both a single control unit or control device and multiple control units or control devices operating collectively to provide some defined control function. To constitute a control device or control unit, a suitable instruction set may be provided, which, when executed, causes the control unit or computing device to implement the control techniques defined herein. The instruction set may preferably be incorporated into the one or more electronic processors. Alternatively, the instruction set may be provided as software stored in one or more memories associated with the control device so as to be executed on the computing device. A control unit or control device may be implemented in software running on one or more processors. One or more other control units or control devices may be implemented in software running on one or more processors, optionally the same one or more processors as the first control device. Other suitable configurations can also be used.

[0037] Hereinafter, one or more embodiments of the present invention will be described merely illustratively with reference to the accompanying drawings. [Brief explanation of the drawing]

[0038] [Figure 1] A schematic diagram of a hydrogen recovery system according to the first embodiment of the present invention, operating in startup mode, is shown. [Figure 2] Figure 1 shows a schematic diagram of the hydrogen recovery system operating in steady-state mode. [Figure 3] Figures 1 and 2 show schematic diagrams of the control devices used to control the operation of the hydrogen recovery system. [Figure 4]Figures 1 and 2 show schematic diagrams of the electrochemical pumps in the hydrogen recovery system. [Figure 5] This is a first block diagram illustrating the operation of a hydrogen recovery system according to one embodiment of the present invention. [Figure 6] A schematic diagram of a hydrogen recovery system according to a second embodiment of the present invention, operating in startup mode, is shown. [Figure 7] Figure 5 shows a schematic diagram of the hydrogen recovery system operating in steady-state mode. [Modes for carrying out the invention]

[0039] A hydrogen recovery system 1 according to one embodiment of the present invention will be described below with reference to the attached drawings. The hydrogen recovery system 1 is configured to extract hydrogen gas (H2) from a mixture of process gases.

[0040] In this specification, the volumetric flow rate of gas is described with reference to the standard liters / minute (SLM or SLPM) of gas under standard temperature and pressure conditions (STP).

[0041] The hydrogen recovery system 1 of this embodiment is configured to recover hydrogen from process gas exhausted from a vacuum system 3. The process gas is supplied to the hydrogen recovery system 1 at a process gas supply pressure below atmospheric pressure. The hydrogen recovery system 1 can operate in a startup mode as shown in Figure 1 and a steady-state mode as shown in Figure 2. The vacuum system 3 in this embodiment is an extreme ultraviolet (EUV) system and is configured to establish a vacuum in a work chamber (not shown) for performing EUV processes such as EUV lithography. The vacuum system 3 can also be used for other applications. For example, the vacuum system 3 can be used in semiconductor etching processes or chemical vapor deposition (CVD) processes. The hydrogen recovery system 1 can be integrated into the vacuum system 3. In this embodiment, the hydrogen recovery system 1 is a separate system connected to the vacuum system 3.

[0042] The vacuum system 3 comprises a system vacuum pump 5. The vacuum pump 5 can be, for example, a dry pump. The vacuum pump 5 operates to pump process gas from the vacuum system 3. The vacuum system 3 in this embodiment is an EUV system that relies on hydrogen gas. The resulting process gas exhausted from the vacuum pump 5 of the vacuum system 3 consists mainly of hydrogen gas. However, the process gas exhausted from the EUV system may be contaminated with other process gases. For example, the process gas may contain nitrogen supplied to the vacuum pump 5 to facilitate pumping. In this specification, the mixture of hydrogen and other process gases is referred to as the “process gas”. In this embodiment, the process gas is introduced into the hydrogen recovery system 1 at a flow rate of 1000 SLM. The vacuum pump 5 in this embodiment comprises a first pumping gas source 7 for selectively introducing an inert gas, such as nitrogen (N2), to facilitate pumping. A first gas supply valve 8 is provided to control the supply of gas from the first pumping gas source 7. The first pump-supplied gas source 7 is configured to introduce nitrogen (N2) gas into the vacuum pump 5 at a rate of 200 SLM. The hydrogen recovery system 1 may optionally include a reservoir 9 for storing process gas discharged from the vacuum pump 5. In the embodiment shown in Figure 1, the reservoir 9 is absent.

[0043] The hydrogen recovery system 1 includes an electrochemical pump 11 for extracting hydrogen from process gas. The electrochemical pump 11 is an electrochemical hydrogen pump (compressor) for pumping hydrogen by an electrochemical process. The electrochemical pump 11 includes a single-stage stack. In a modified configuration, the electrochemical pump 11 may include multiple stages. The electrochemical pump 11 includes an anode compartment 13 having at least one anode 14, a cathode compartment 15 having at least one cathode 16, and a membrane 17 positioned between the anode compartment 13 and the cathode compartment 15. The membrane 17 is an electrochemical membrane and can be a polymer membrane. The membrane 17 can consist of one or more of the following: a polybenzimidazole (PBI) membrane, a proton-doped hydrocarbon membrane, a solid acid membrane such as a cesium dihydrogen phosphate membrane, or a perfluorosulfonic acid-based membrane. The membrane 17 can be made of Nafion®. A direct current (DC) power supply 20 is provided to supply current and voltage to the EC pump 11. Figure 4 shows a schematic diagram of the electrochemical pump 11. In a modified example, the hydrogen recovery system 1 may include two or more anode compartments 13 and / or two or more cathode compartments 15. The anode compartment 13 includes an anode compartment inlet 23 for receiving process gas from the vacuum pump 5 and an anode compartment outlet 25 for discharging waste gas with reduced hydrogen content. The waste gas may be called anode waste gas. The cathode compartment 15 includes a cathode compartment outlet 27 for discharging hydrogen separated from the process gas.

[0044] The process gas is introduced into the anode compartment 13 of the electrochemical pump 11 at an anode compartment inlet pressure ACP-IN. The waste gas is discharged from the anode compartment 13 at an anode compartment outlet pressure ACP-OUT. A larger-than-usual flow field cross-section can be used to reduce the pressure drop across the electrochemical pump 11. The gas diffusion layer can be designed to maximize porosity and thus minimize the pressure drop. The temperature of the electrochemical pump 11 can be lower than that of a normal electrochemical pump to minimize the evaporation of water from the proton-conducting membrane. If a large amount of water evaporates, hydrogen diffusion into the gas diffusion layer and catalyst layer may be inhibited. Optionally, the electrochemical pump 11 may be equipped with a heat exchanger. The heat exchanger can, for example, allow cooling of the membrane 17 to reduce or prevent condensation. At least one anode 14 and / or at least one cathode 16 may contain one of platinum group metal particles and carbon-supported platinum group metal particles. Because low hydrogen partial pressures easily generate mass transfer overpotentials compared to conventional electrochemical pump systems, a variety of anode catalysts can be used. Humidification schemes may rely on direct water injection to the cathode to limit the amount of moisture in the anode.

[0045] The first control valve 29 is provided to selectively supply process gas from the vacuum pump 5 to the electrochemical pump 11. In this embodiment, the first control valve 29 is a three-way valve. The first control valve 29 operates to supply process gas to the anode compartment inlet 23 or the abatement unit 31 of the electrochemical pump 11.

[0046] Exhaust gas is discharged from the electrochemical pump 11 via the anode compartment outlet 25. In this embodiment, the exhaust gas contains a mixture of hydrogen and nitrogen. The hydrogen component may have a flow rate of 200 SLM, and the nitrogen may have a flow rate of 200 SLM. A second control valve 33 is provided to control the exhaust gas discharged from the anode compartment outlet 25 of the electrochemical pump 11. In this embodiment, the second control valve 33 is a three-way valve. The second control valve 33 is located in an outlet passage 35 connected to the anode compartment outlet 25. The second control valve 33 is selectively operable to connect the anode compartment outlet 25 to an auxiliary vacuum pump 37. The second control valve 33 can be configured to bypass the auxiliary vacuum pump 37, for example, during steady-state operation. The auxiliary vacuum pump 37 includes an auxiliary vacuum pump inlet 38 that is in fluid communication with the anode compartment outlet 25, and an auxiliary vacuum pump outlet 39 that is in fluid communication with the abatement unit 31. The auxiliary vacuum pump 37 operates to pump process gas through the anode compartment 13 and pump waste gas to the abatement unit 31. Alternatively, at least a portion of the waste gas can be recirculated through the electrochemical pump 11 or supplied to another electrochemical pump 11 for further processing. In this embodiment, the auxiliary vacuum pump 37 is shown as a dedicated pump. In a modified example, the hydrogen recovery system 1 may use another vacuum pump from the vacuum system 3 or the associated abatement system. This allows the hydrogen recovery system 1 to "piggyback" the existing vacuum pump to pump process gas through the electrochemical pump 11. A second pump supply gas source 40 is provided to selectively supply an inert gas, such as nitrogen, to the auxiliary vacuum pump 37. A second gas supply valve 41 is provided to control the supply of gas from the second pump supply gas source 40 to the auxiliary vacuum pump 37.

[0047] A throttle valve 43 is located on the inlet side of an auxiliary vacuum pump 37 to control the pressure of the exhaust gas at the anode compartment outlet 25. A control device 45 is provided to control the operation of the throttle valve 43. In this embodiment, the control device 45 includes a proportional-integral-derivative (PID) control device, but other types of control devices are also possible. The control device 45 receives an outlet pressure signal SP-OUT from an outlet pressure sensor 47 configured to measure the anode compartment outlet pressure ACP-OUT. Optionally, the control device 45 can receive an inlet pressure signal SP-IN from an inlet pressure sensor (not shown in this embodiment) configured to measure the anode compartment inlet pressure ACP-IN. The control device 45 is configured to control the throttle valve 43 to maintain the anode compartment outlet pressure ACP-OUT at a setpoint (target) pressure. In this embodiment, the setpoint pressure is predetermined as 250 mbar. A higher or lower setpoint pressure can be specified. The control device 45 selectively opens and closes the throttle valve 43 to maintain the anode compartment outlet pressure ACP-OUT at least substantially equal to the setpoint pressure. Alternatively, the control device 45 can control the throttle valve 43 to maintain the anode compartment outlet pressure ACP-OUT within a target pressure range. A second control valve 33 selectively operates to connect the anode compartment outlet 25 to a bypass passage 49 in order to bypass the auxiliary vacuum pump 37. A check valve 51 is provided to allow unidirectional flow of gas through the bypass passage 49. The bypass passage 49 is connected to a detoxification unit 31 for detoxifying exhaust gases.

[0048] The electrochemical pump 11 operates to extract and compress hydrogen from the process gas. The hydrogen is collected at at least one cathode 16 located in the cathode compartment 15. The hydrogen is discharged from the electrochemical pump 11 through the cathode compartment outlet 27. The hydrogen is discharged from the cathode compartment 15 at a cathode compartment outlet pressure CCP-OUT. In this embodiment, the hydrogen is discharged from the cathode compartment outlet 27 at a flow rate of 800 SLM and a cathode compartment outlet pressure CCP-OUT of approximately 135 psi (931 kPa) (approximately 120 psig). An outlet channel 53 is connected to the cathode compartment outlet 27 to send the hydrogen to a mixing box 55. The hydrogen is stored in the mixing box 55 and can then be used in the EUV process. If the purity of the hydrogen collected in the mixing box 55 is too low, the mixing box 55 can be connected to a detoxification unit 31. Optionally, the hydrogen in the mixing box 55 can be replenished from an external source, for example, to maintain an appropriate supply for the EUV process.

[0049] The hydrogen recovery system 1 includes a control device 59. As shown in Figure 3, the control device 59 is an electronic control unit (ECU) comprising at least one electronic processor 60 and a memory device 61. The at least one electronic processor 60 is configured to execute a series of computational instructions stored in the memory device 61 to perform the method(s) described herein. The electronic processor 60 has at least one electrical input 62 for receiving one or more sensor signals and at least one electrical output 63 for outputting one or more control signals CS-n. The control device 59 is configured to control the operation of the electrochemical pump 11. In particular, the control device 59 is configured to control the current and / or voltage supplied to the electrodes of the electrochemical pump 11 by the power supply 20. The control device 59 is configured to determine the current setpoint and / or voltage setpoint of the electrochemical pump 11. The control device 59 controls the power supply 20 such that the current supplied to the electrochemical pump 11 is at least substantially equal to the determined current setpoint. Alternatively, the control device 59 controls the power supply 20 such that the voltage supplied to the electrochemical pump 11 is at least substantially equal to a determined voltage setpoint. As described herein, the control device 59 can increase or decrease the current setpoint and / or voltage setpoint based on one or more operating parameters of the hydrogen recovery system 1. The control device 59 can also be configured to control the first control valve 29, the second control valve 33, and the auxiliary vacuum pump 37. The control device 59 is configured to control the supply of nitrogen to at least one of the vacuum pump 5 and the auxiliary vacuum pump 37.

[0050] During use, the vacuum pump 5 is configured to evacuate the gas at a pressure below atmospheric pressure, for example, below 200 mbar or below 300 mbar. This is in contrast to the configuration of the prior art in which the corresponding pump is typically configured to evacuate at atmospheric pressure. The electrochemical pump 11 acts as an additional (final) pump stage and extracts hydrogen present in the process gas evacuated from the vacuum pump 5. The electrochemical pump 11 operates to compress the hydrogen extracted from the process gas. In at least certain embodiments, the electrochemical pump 11 can compress the hydrogen above atmospheric pressure.

[0051] The control device 59 is configured to control the operation of the hydrogen recovery system 1 in a start-up mode and a steady-state mode. The start-up mode can be initiated while the vacuum system 3 is operating or before the vacuum system 3 is activated. The start-up mode includes activating the electrochemical pump 11. A potential difference is established between at least one anode 14 and at least one cathode 16. The control device 59 controls a current setpoint to control the operation of the electrochemical pump 11. The control device 59 sets a first control valve 29 to direct process gas from the vacuum system 3 to the anode compartment 13 of the electrochemical pump 11. The control device 59 sets a second control valve 33 to activate the auxiliary vacuum pump 37 and direct waste gas from the vacuum system 3 to the auxiliary vacuum pump 37. The auxiliary vacuum pump 37 operates to pump the process gas through the electrochemical pump 11. The waste gas is discharged from the anode compartment 13 and pumped to the abatement unit 31. In this embodiment, the control device 59 is configured to supply nitrogen to the vacuum pump 5 in the start-up mode. Nitrogen can be supplied, for example, at a flow rate of 200 SLM.

[0052] The control device 59 determines that the start-up mode is complete when the pressure in the anode compartment outlet passage 35 reaches a predetermined setpoint and / or becomes at least substantially constant (i.e., HRC1 is operating in a steady state). In this embodiment, the control device 59 determines that the start-up mode is complete when the pressure in the anode compartment outlet passage 35 is less than 250 mbar. Based on this determination, the control device 59 transitions to steady-state mode operation. The PID control device 45 controls the throttle valve 43 to maintain the pressure at the anode compartment outlet 25 at least substantially equal to the setpoint pressure. In this embodiment, the setpoint pressure is defined as 250 mbar. The setpoint pressure may be greater than or less than 250 mbar. The control device 59 is configured, at least in part, to close the first gas supply valve 8 to reduce or stop the supply of nitrogen from the first pump-supplied gas source 7 when the outlet pressure signal SP-OUT from the outlet pressure sensor 47 indicates that the anode compartment outlet pressure ACP-OUT is less than the setpoint pressure, for example, 250 mbar. Optionally, the control device 59 can be configured to supply nitrogen to the auxiliary vacuum pump 37. In this embodiment, nitrogen is supplied to the auxiliary vacuum pump 37 at a flow rate of 50 SLM. The auxiliary vacuum pump 37 operates to achieve or maintain steady-state pumping at a flow rate of approximately 250 SLM. The outlet pressure of the auxiliary vacuum pump 37 can be at least substantially equal to atmospheric pressure. The exhaust gas is pumped to the detoxification unit 31 for detoxification.

[0053] The electrochemical pump 11 extracts at least a portion of the hydrogen present in the process gas exhausted from the vacuum pump 5. The extracted hydrogen is collected at at least one cathode 16 and stored in the cathode compartment 15. The electrochemical pump 11 operates to pressurize the hydrogen extracted from the process gas. The hydrogen is discharged from the cathode compartment 15 through the cathode compartment outlet 27 and recovered in the mixing box 55. In this embodiment, the hydrogen flow rate is 800 SLM, and the cathode compartment outlet pressure CCP-OUT is approximately 135 psi (931 kPa) (approximately 120 psig).

[0054] The hydrogen recovery system 1 according to this embodiment can reduce the required output pressure of the vacuum pump 5, thereby improving pump efficiency and power saving. As an example, power saving of 2 kW per pump can be achieved. The vacuum system 3 can be equipped with multiple pumps, for example, five vacuum pumps. Power saving is possible with respect to each pump. The electrochemical pump 11 can enable the recovery of high-purity hydrogen that contains almost no nitrogen impurities. In at least certain embodiments, the hydrogen recovery system 1 enables the recovery of approximately 80% to 100% of the hydrogen introduced into the EUV system.

[0055] Next, a method for recovering hydrogen from process gas using the hydrogen recovery system 1 will be described with reference to the first block diagram 100 shown in Figure 5. The control device 59 is configured to perform the method(s) described herein. As described herein, the hydrogen recovery system 1 comprises an electrochemical (hydrogen) pump (11) having an anode compartment 13 and a cathode compartment 15. A membrane 17 is located between the anode compartment 13 and the cathode compartment 15. The method includes the step of discharging the process gas from the vacuum pump 5 of the vacuum system 3 (block 105). Optionally, an inert gas such as nitrogen can be introduced into the vacuum pump 5 to facilitate the pumping of the process gas (block 110). An auxiliary vacuum pump 37 located on the outlet side of the electrochemical pump 11 is activated. The vacuum system 3 can be, for example, an extreme ultraviolet (EUV) system 3. A first control valve 29 is configured to introduce the process gas into the electrochemical pump 11 (block 115). The second control valve 33 is configured to direct the exhaust gas from the electrochemical pump 11 to the auxiliary pump 37 (block 120). The auxiliary pump 37 is activated (block 125). The auxiliary pump 37 pumps the process gas through the anode chamber 13 of the electrochemical pump 11 (block 125). Optionally, the throttle valve 45 can be operated to control the supply of exhaust gas to the auxiliary pump 37 (block 130). The throttle valve 45 can be controlled to maintain a setpoint pressure of the exhaust gas supplied to the auxiliary pump 37. The auxiliary pump 37 pumps the exhaust gas to the abatement unit 31 (block 135). The electrochemical pump 11 is activated to filter at least some of the hydrogen gas present in the process gas (block 140). The recovered hydrogen is discharged from the cathode compartment 15 to a reservoir (mixing box 55), for example, for storage (block 145). This method may optionally include a step of controlling the current and / or voltage supplied to the electrochemical pump 11 in order to control the recovery of hydrogen from the process gas. When the exhaust gas from the electrochemical pump 11 is output to the auxiliary pump 37 at a predetermined pressure threshold, for example, an anode compartment outlet pressure ACP-OUT of less than 250 mbar, the supply of nitrogen to the vacuum pump 5 is stopped (block 150).The pressure threshold can be defined to correspond to the steady-state operation of the hydrogen recovery system 1.

[0056] During steady-state operation, the second control valve 33 is configured to bypass the auxiliary pump 37 (block 155). During steady-state operation of the hydrogen recovery system 1, the operating speed of the auxiliary pump 37 can be reduced or the auxiliary pump 37 can be stopped (block 160). Exhaust gas from the anode compartment 13 is sent directly to the abatement unit 31 (block 165). The check valve 51 can at least substantially prevent the return of exhaust gas to the electrochemical pump 11 (block 170). The method may include, for example, a step of restarting the pump supply process if the pressure of the exhaust gas discharged from the anode compartment 13 is greater than or less than a predetermined threshold (block 175). The method may include a step of selectively controlling the supply of exhaust gas to the auxiliary pump 37 to perform a purging operation, for example, a step of pulse-controlling the control valve to intermittently supply exhaust gas while the auxiliary pump 37 is operating. The hydrogen recovery process is stopped when the vacuum system 3 is stopped (block 180).

[0057] This method includes selectively increasing or decreasing the current supplied to the electrochemical pump 11. This method may include decreasing the current supplied to the electrochemical pump 11 based on the determination that at least one of the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT of the electrochemical pump 11 is below a predetermined pressure threshold. This method may also include increasing the current supplied to the electrochemical pump 11 based on the determination that at least one of the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT of the electrochemical pump 11 is greater than a predetermined pressure threshold.

[0058] Next, further embodiments of the hydrogen recovery system 1 will be described with reference to Figures 6 and 7. The hydrogen recovery system 1 according to this embodiment is an evolution of the embodiment shown in Figures 1 and 2. The same reference numerals are used for the same components.

[0059] As shown in Figure 6, the hydrogen recovery system 1 of this embodiment includes a reservoir 9 for storing process gas exhausted from the vacuum system 3. The hydrogen recovery system 1 includes an inlet pressure sensor 65 for measuring the anode compartment inlet pressure ACP-IN at the anode compartment inlet 23. The inlet pressure sensor 65 outputs an inlet pressure signal SP-IN to the control device 59. An outlet pressure sensor 67 is provided for measuring the anode compartment outlet pressure ACP-OUT at the anode compartment outlet 27. The outlet pressure sensor 67 outputs an outlet pressure signal SP-OUT to the control device 59. The control device 59 is configured to control the operation of the electrochemical pump 11 based on at least one of the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT.

[0060] The control device 59 is configured to reduce the current supplied to the electrochemical pump 11 based on the determination that the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT are below a predetermined first pressure threshold. In this embodiment, the first pressure threshold is 250 mbar. It should be understood that the first pressure threshold may be greater than or less than 250 mbar. The control device 59 is configured to reduce the current supplied to the electrochemical pump 11 by a predetermined percentage, for example, 1%, based on the determination that both the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT are below a predetermined first pressure threshold.

[0061] The control device 59 is configured to increase the current supplied to the electrochemical pump 11 based on the determination that the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT are greater than a predetermined second pressure threshold. In this embodiment, the second pressure threshold is 250 mbar. It should be understood that the second pressure threshold may be greater than or less than 250 mbar. The control device 59 is configured to increase the current supplied to the electrochemical pump 11 by a predetermined percentage, for example, 1%, based on the determination that both the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT are greater than a predetermined first pressure threshold.

[0062] In this embodiment, the anode compartment outlet passage 35 comprises first and second outlet control valves 69 and 71 located in the outlet passage 35 connected to the anode compartment outlet 25. In this embodiment, the first and second outlet control valves 69 and 71 are located between the second control valve 33 and the throttle valve 43. It should be understood that the positions of the first and second outlet control valves 69 and 71 in the outlet passage 35 can vary. In this embodiment, each of the first and second outlet control valves 69 and 71 is a pneumatic valve. Other types of valves, such as solenoid valves, can be used. The first and second outlet control valves 69 and 71 are arranged in parallel with each other. The operation of the first and second outlet control valves 69 and 71 can be controlled by the control device 59. A flow limiter 73 is provided in series with the second outlet control valve 71. The flow limiter 73 enables deadhead operation of the hydrogen recovery system 1.

[0063] After reaching a desired operating pressure, for example 250 mbar, the supply of nitrogen to the vacuum pump 5 can be stopped. Under these operating conditions, the gas exiting the vacuum pump 5 is at least substantially pure hydrogen. In this state, the exhaust port of the anode compartment 13 can be completely closed. In this embodiment, the anode compartment 13 can be closed by closing the first and second outlet control valves 69, 71. Alternatively or additionally, a separate, dedicated on / off valve (not shown) can be provided to close the outlet of the anode compartment 13. The pressure inside the electrochemical pump 11 will begin to rise. The control device 59 proportionally increases the current and / or voltage supplied to the electrochemical pump 11 until a steady state is reached in which all hydrogen flowing in from the vacuum pump 5 is transported through the electrochemical membrane 17. The extremely pure hydrogen exiting the electrochemical pump 11 prevents the rapid accumulation of inert gas components. In some cases, accumulation of inert components such as trace levels of nitrogen may necessitate ventilation / purging of the anode compartment 13. This is achieved by temporarily opening the first and second outlet control valves 69, 71, allowing a transient flow of hydrogen (and trace amounts of inert components) to flow out of the anode compartment 13 and into the process waste line. The advantage of this mode is that nearly 100% of the hydrogen in the vacuum pump is captured and pressurizes the cathode compartment 15 of the electrochemical pump 11. This hydrogen is recycled back into the original upstream process, forming a "closed loop" of hydrogen. While hydrogen supply may require replenishment, this can be reduced, at least in certain embodiments. A hydrogen recovery system 1 according to a particular aspect of the present invention can simplify logistics, costs, and / or the environmental impact of hydrogen production.

[0064] A mass flow meter (MFM) 75 is provided to measure the mass flow rate of hydrogen from the cathode compartment 15. The MFM 75 outputs a flow rate signal SMF to the control device 59. In this embodiment, the MFM 75 is located inside the mixing box 55. The MFM 75 may also be located separately from the mixing box 55, for example, at the outlet of the cathode compartment 15. The control device 59 is configured to determine the current setpoint of the electrochemical pump 11 based on the mass flow rate of hydrogen. The current setpoint can be determined to maintain steady-state operation of the hydrogen recovery system 1. The current setpoint can be determined to supply a desired hydrogen flow rate from the electrochemical pump 11. The current setpoint may correspond to the sum of the base (steady-state) current and the current "gain". The base current for steady-state operation of the hydrogen recovery system 1 corresponds to the mass flow rate measurement of two electrons input for one hydrogen molecule pumped. The current "gain" can be superimposed on the base current. The current "gain" can be determined based on the measured pressure at the anode compartment inlet 23 and / or the anode compartment outlet 25. The pressure measured at the anode compartment inlet 23 and / or the anode compartment outlet 25 can be compared to a predetermined target pressure. Alternatively or additionally, the pressures measured at the anode compartment inlet 23 and the anode compartment outlet 25 can be compared to each other, for example, to determine a pressure difference. The control device 59 can be configured to increase the current "gain" by, for example, 1% if at least one of the pressures measured at the anode compartment inlet 23 and the anode compartment outlet 25 is below a predetermined pressure threshold, such as 250 mbar. The control device 59 can be configured to decrease the current "gain" by, for example, 1% if at least one of the pressures measured at the anode compartment inlet 23 and the anode compartment outlet 25 exceeds a predetermined pressure threshold, such as 250 mbar.

[0065] The hydrogen recovery system 1 includes a control device 45 for controlling the operation of a throttle valve 43. An auxiliary pump inlet pressure sensor 75 is provided to measure the inlet pressure of the auxiliary vacuum pump 37. The throttle valve 43 is controlled based on the measured inlet pressure of the auxiliary vacuum pump 37. The control device 59 is configured to control the operation of the auxiliary vacuum pump 37 based on the measured pressure at the inlet of the auxiliary vacuum pump 37. In this embodiment, the control device 59 is configured to restart the hydrogen recovery process based on the determination that the measured pressure at the inlet of the auxiliary vacuum pump 37 is greater than a predetermined upper threshold, for example, 500 mbar. Restarting the hydrogen recovery system 1 includes controlling the first pump supply gas source 7 to supply nitrogen to the vacuum pump 5 and / or controlling the second pump supply gas source 40 to supply nitrogen to the auxiliary vacuum pump 37.

[0066] The operation of the hydrogen recovery system 1 may cause impurities to accumulate in the auxiliary vacuum pump 37 and / or associated flow paths. The control device 59 in this embodiment is configured to perform a purging process to discharge and dispose of the accumulated impurities. The control device 59 operates the auxiliary vacuum pump 37 by closing the first and second outlet control valves 69, 71. At least one of the first and second outlet control valves 69, 71 can be pulsed open to introduce waste gas into the auxiliary vacuum pump 37, thereby purging and disposing of the accumulated impurities.

[0067] During use, the control device 59 is configured to close the first and second outlet control valves 69 and 71 when the hydrogen recovery system 1 is operating in a steady state, as schematically shown in Figure 7. The control device 59 can continuously determine the current setpoint of the electrochemical pump 11 based on the mass flow rate measured by the MFM 75. During steady-state operation, the control device 59 can control the current supplied to the electrochemical pump 11 based on the measured mass flow rate and at least one of the anode compartment inlet pressure ACP-IN and the anode compartment outlet pressure ACP-OUT. For example, the control device 59 can control the current supplied to the electrochemical pump 11 based on the measured mass flow rate and the anode compartment inlet pressure ACP-IN. During steady-state operation, the control device 59 can stop the auxiliary vacuum pump 37.

[0068] It should be understood that various changes and modifications can be made to the present invention without departing from the scope of this application. For example, a pressure sensor may be provided at the cathode compartment outlet 27. The control device 59 may be configured to control the current setpoint of the electrochemical pump 11 based on the pressure measured at the cathode compartment outlet 27. In certain embodiments, the auxiliary vacuum pump 37 may be omitted.

[0069] Optionally, the hydrogen recovery system 1 may be equipped with a dryer for drying the recovered hydrogen gas. For example, the dryer can perform a drying operation so that the hydrogen can be reintroduced into the vacuum system 3.

[0070] This invention particularly describes the extraction of hydrogen from process gases supplied at or below atmospheric pressure. It should be understood that the systems and methods described herein can be used to recover hydrogen from process gases supplied at or above atmospheric pressure.

[0071] Block diagram labels [Table 1] [Explanation of symbols]

[0072] 1. Hydrogen Recovery System (HRS) 3. Vacuum System 5. Vacuum pump 7. First pump-supplied gas source 8. First gas supply valve 9. Reservoir (buffer tank) 11 Electrochemical pumps 13 Anode compartment 14 Anode 15 Cathode Compartments 16 Cathode 17 membrane 19 (DC) power supply 23 Anode compartment entrance 25 Anode compartment exit 27 Cathode Compartment Exit 29. First control valve 31 pest control units 33. Second control valve 35 Exit Route 37. Auxiliary vacuum pump 38 Auxiliary vacuum pump inlet 39 Auxiliary vacuum pump outlet 40 Second pump-supplied gas source 41 Second gas supply valve 43 Throttle valve 45 Throttle valve control device 47 Outlet pressure sensor 49 Bypass channel 51 Check valve 53 Cathode Compartment Outlet Channel 55 Mixing Box 59 Control device 60 processors 61 Storage device 62 Electrical Inputs 63 Electrical output 65 Inlet pressure sensor 67 Outlet pressure sensor 69 First outlet control valve 71 Second outlet control valve 73 Flow limiter 75 Mass Flowmeter 77. Auxiliary pump pressure recovery

Claims

1. A hydrogen recovery system for extracting hydrogen from process gases from a semiconductor manufacturing process, A vacuum pump capable of operating to supply the process gas to the hydrogen recovery system at near-atmospheric pressure, A vacuum system comprising, The aforementioned hydrogen recovery system is, An electrochemical pump for extracting at least a portion of the hydrogen generated in the process gas, comprising: an anode compartment having at least one anode; a cathode compartment having at least one cathode; and a membrane disposed between the anode compartment and the cathode compartment; A control device for controlling the operation of the electrochemical pump, an anode compartment inlet for introducing the process gas into the anode compartment, An anode compartment outlet for discharging exhaust gas from the anode compartment, A cathode compartment outlet for discharging hydrogen gas extracted from the process gas, A vacuum system equipped with...

2. The vacuum system according to claim 1, comprising a first pressure sensor for measuring the anode compartment inlet pressure (ACP-IN) at the anode compartment inlet and a second pressure sensor for measuring the anode compartment outlet pressure (ACP-OUT) at the anode compartment outlet, wherein the control device is configured to control the operation of the electrochemical pump based on at least one of the anode compartment inlet pressure (ACP-IN) and the anode compartment outlet pressure (ACP-OUT).

3. The vacuum system according to claim 2, wherein the control device is configured to control the operation of the electrochemical pump based on the pressure difference between the anode compartment inlet pressure (ACP-IN) and the anode compartment outlet pressure (ACP-OUT).

4. The vacuum system according to claim 2, wherein the control device is configured to reduce the current and / or voltage supplied to the electrochemical pump based on a determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is below a predetermined pressure threshold.

5. The vacuum system according to claim 2, wherein the control device is configured to increase the current and / or voltage supplied to the electrochemical pump based on a determination that at least one of the anode compartment inlet pressure and the anode compartment outlet pressure is greater than a predetermined pressure threshold.

6. The system includes a mass flow meter for measuring the mass flow rate of hydrogen from the cathode compartment, The vacuum system according to any one of claims 1 to 5, wherein the control device is configured to determine a current setting value for the electrochemical pump based on the mass flow rate of hydrogen.

7. The vacuum system according to any one of claims 1 to 5, comprising an auxiliary pump in fluid communication with the outlet of the anode compartment, wherein the auxiliary pump is operable to pump the process gas through the anode compartment.

8. The vacuum system according to claim 7, further comprising an auxiliary pump inlet pressure sensor for measuring the inlet pressure of the auxiliary pump, wherein the control device is configured to control the operation of the auxiliary pump based on the inlet pressure of the auxiliary pump.

9. A gas source is provided to supply an inert gas to the auxiliary pump and to facilitate the pumping of the process gas through the anode compartment. The vacuum system according to claim 8, wherein the control device is configured to control the gas source and supply inert gas to the auxiliary pump based on a determination that the inlet pressure of the auxiliary pump is greater than a predetermined upper threshold.

10. The vacuum system according to claim 7, further comprising a throttle valve for controlling the discharge of exhaust gas from the anode compartment to the auxiliary pump.

11. The vacuum system according to claim 8, further comprising at least one valve operable to isolate the auxiliary pump from the anode compartment outlet.

12. The vacuum system according to claim 11, wherein the control device is configured to operate the auxiliary pump and selectively open one or more of the at least one valve to purge impurities.

13. The vacuum system according to claim 8, further comprising a control valve for selectively bypassing the auxiliary pump, wherein the control device is configured to actuate the control valve to bypass the auxiliary pump for steady-state operation of the hydrogen recovery system.

14. The vacuum system according to claim 13, wherein the control device is configured to output a control signal that prevents the introduction of an inert gas into the vacuum system during steady-state operation of the hydrogen recovery system.

15. A method for recovering hydrogen from process gases from a semiconductor manufacturing process in a vacuum system using an electrochemical pump, wherein the electrochemical pump comprises an anode compartment having at least one anode, a cathode compartment having at least one cathode, and a membrane disposed between the anode compartment and the cathode compartment, and the method is The steps include introducing the process gas from a vacuum pump into the anode section of the electrochemical pump at near-atmospheric pressure, The steps include: discharging exhaust gas from the anode compartment, The steps include: discharging hydrogen gas from the cathode compartment; A method that includes this.

16. The method according to claim 15, further comprising the step of controlling the electrochemical pump to control the recovery of hydrogen from the process gas.

17. The method according to claim 15 or 16, further comprising the step of preventing the introduction of an inert gas into the process gas when the electrochemical pump is operating in a steady state.

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