JP2004233021A - Clean room exhausting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit a clean room to handle hazardous gas at a low initial cost. <P>SOLUTION: A hydrogen gas concentration detector (hazardous gas concentration measuring device) 73 is provided inside a clean room body 2 to measure hydrogen gas (hazardous gas) concentration through a control device 71. If the hydrogen gas concentration exceeds a predetermined concentration level, a nitrogen gas valve 63 is opened to pressurize nitrogen gas to a circulation dumper 33, an exhausting dumper 52, and a nozzle 53d. Opening of the nitrogen gas valve 63 causes the circulation dumper 33 to close, the exhausting dumper 52 to open and the nozzle 53d to inject nitrogen gas. A negative pressure generated in a venturi tube 53 by the nitrogen gas injection, causes air to be exhausted from the clean room body 2. In this way, a clean room 1 can handle hazardous gas and reduce the load of an air conditioner, providing a safer and more economical clean room. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a clean room exhaust system that detects a concentration of a toxic gas, which is a dangerous area of a combustible gas or a toxic gas used in a clean room, and constantly manages a working room environment in a safer state.
[0002]
[Prior art]
Clean rooms used for manufacturing, research, and development in various fields such as semiconductor devices and pharmaceuticals use an air conditioner equipped with high-performance filters to introduce outside air and circulate indoor air to constantly maintain the clean room interior. It is kept at positive pressure to keep out dust and dirt from outside. Exceptionally, when using a gas such as flammable gas or toxic gas in a clean room, or when working with the generation of a reactive gas due to the reaction of a chemical solution, the use of such toxic gas Naturally, flammable, toxic, and reactive gases are collectively referred to as toxic gases), and it is necessary to provide a facility for discharging harmful gases in the clean room body in consideration of safety.
[0003]
As a method for reliably discharging harmful gases while the clean room is maintained at a positive pressure, a method of handling flammable gas while covering the electronic device serving as an ignition source with a chamber and further maintaining the inside of the chamber at a positive pressure (for example, And a method of connecting a device using a combustible gas, such as a reaction furnace, to a cited air path (for example, Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2001-227773 (Pages 2-3, FIG. 1, FIG. 2, FIG. 3)
[Patent Document 2]
JP 2001-336797 A (page 5, FIG. 6)
[0005]
[Problems to be solved by the invention]
However, in the case of the above-mentioned Patent Documents 1 and 2, in order to cope with a case where the harmful gas leaks from a portion where the harmful gas is used, in addition to the local exhaust equipment described in the document, the exhaust of the entire clean room is performed. Required an exhaust duct. In this way, when exhausting the entire clean room, in order to keep the inside of the clean room at a positive pressure at all times, the air conditioner must have a large output in order to cope with the load accompanying the continuous introduction of outside air. Initial facility costs for clean rooms were high.
[0006]
In addition, when combustible gas is handled inside the clean room, the blower in the exhaust duct must be of explosion-proof type. For this reason, there has been a problem that the initial equipment cost for the clean room is further increased. Furthermore, in a conventional clean room, it is necessary to constantly assign personnel for harmful gas concentration management (risk management) so that a power outage can be dealt with promptly, and high costs are required for continuous maintenance.
[0007]
It is an object of the present invention to provide a clean room capable of handling harmful gases with relatively low initial equipment costs, and to enable harmful gas concentration management of the clean room with low maintenance costs.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 has a clean room main body in which the inside is maintained at a positive pressure with respect to the outside, and both ends are connected to the clean room main body. A circulation duct that inhales and blows air from the other end, a filter that is provided inside the circulation duct path and filters the air, and a circulation duct opening / closing unit that substantially closes one end of the circulation duct by the pressure of the inert gas. An external air intake duct connected between the circulation duct opening / closing means and the filter and to the circulation duct intermediate portion to take in air outside the clean room main body into the circulation duct intermediate portion, and one end is connected to the clean room main body; The other end is a Venturi tube that injects the inert gas inside the duct and exhausts the air inside the clean room body to the outside Exhaust duct having, the exhaust duct opening and closing means for opening one end of the exhaust duct by the pressure of the inert gas, the circulation duct opening and closing means, the exhaust duct opening and closing means, and the inert gas to the venturi pipe, An inert gas supply device for supplying via an inert gas valve, and a control unit having a device for detecting the concentration of harmful gas inside the clean room main body and measuring the concentration of harmful gas, the control unit comprising: When the concentration of the harmful gas inside the main body exceeds a predetermined concentration value, the circulation duct opening / closing means is substantially closed, the exhaust duct opening / closing means is opened, and the inert gas is supplied to the side where the venturi pipe injects the inert gas. It is characterized by having a control device for opening the valve.
[0009]
According to the first aspect of the present invention, the concentration of the harmful gas in the clean room body is managed by the control device including the harmful gas concentration detector and the measuring device. When the harmful gas concentration exceeds a predetermined concentration value, the control device closes the circulation duct side and opens the exhaust duct side by controlling the inert gas valve. When the circulation duct is substantially closed by the inert gas pressure, the circulation of air in the clean room main body is stopped or suppressed to a very low level. Then, the exhaust duct is opened by the inert gas pressure, and the inert gas is injected from the inside of the Venturi tube toward the outside of the clean room main body. Due to the injection of the inert gas, a large pressure difference is generated between the inside of the clean room main body and the Venturi tube, so that the contaminated air inside the clean room main body is discharged, and the harmful gas concentration is accordingly efficiently discharged. At this time, since the outside air intake duct remains open, the inside of the clean room main body is maintained at a positive pressure even during exhaust by taking in fresh air from this outside air intake duct.
[0010]
The driving force for discharging the harmful gas is generated by injecting the inert gas from the inside of the Venturi tube. The circulation duct and the exhaust duct are driven by an inert gas pressure. Therefore, unlike the case where an electric electric motor fan is provided, these components do not need to have expensive explosion-proof specifications. Furthermore, since harmful gases are diluted with an inert gas and discharged, there is almost no need to provide processing equipment for explosion proof and gas proof outside the clean room. However, specific substances specified in environmental standards are required separately. These facts can also deal with the handling of harmful gases inside the clean room main body with low initial equipment costs.
[0011]
In addition, the discharge of harmful gas is automatically performed for 24 hours by the control device connected to the harmful gas concentration detector. It can cope with the increase in concentration. These facts can also make the management of the concentration of harmful gas unmanned, and the maintenance and management can be performed at low cost. For example, when the concentration of the harmful gas inside the clean room body exceeds a predetermined concentration value, the control means opens an inert gas valve on the side where the inert gas is injected from the Venturi pipe, and then vents the Venturi by the injection of the inert gas. When the inside of the pipe becomes a negative pressure with respect to the inside of the clean room, the internal air is pulled, a fluid force in the harmful gas discharge path is generated, and the exhaust can be performed smoothly.
[0012]
The invention according to claim 2 is the clean room according to claim 1, further comprising an uninterruptible power supply that supplies power to the control device and the inert gas valve, wherein the control device performs the inactive operation when a power failure occurs. The gas valve is opened for a predetermined time.
[0013]
According to the second aspect of the present invention, it is possible to discharge the harmful gas safely and reliably even when the concentration of the harmful gas is repeatedly increased when a power failure occurs due to an accident or disaster. At this time, the mechanical components among the components driven for emission of harmful gas are exhaust ducts and circulation ducts, which are mainly driven by the inert gas pressure of the independent path, so that power supply to the clean room is not possible. Until the restart, the harmful gas can be discharged with a minimum of electric power. Therefore, the harmful gas can be discharged from the clean room main body with high reliability at the time of emergency or power failure. Therefore, it is not necessary to constantly arrange personnel in preparation for a power failure or the like in the event of an accident or the like, and the harmful gas concentration in the clean room can be managed economically with high safety.
[0014]
According to a third aspect of the present invention, there is provided the clean room according to the first or second aspect, further comprising an opening degree adjusting means for adjusting an opening degree of at least one of the circulation duct opening / closing means and the exhaust duct opening / closing means. It is characterized by the following.
[0015]
According to the third aspect of the invention, at least one of the circulation duct opening / closing means and the exhaust duct opening / closing means can be adjusted by the opening degree adjustment means, so that the flow rate of air taken in by the circulation duct and the exhaust air can be adjusted. The flow rate of air exhausted through the duct can be adjusted. As a result, it is possible to adjust the pressure difference between the inside and the outside of the clean room as a component for discharging harmful gas. Therefore, since there is no need to provide a component for adjusting the differential pressure, a clean room capable of safely managing the concentration of harmful gas can be provided at a lower cost.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The clean room exhaust system equipment according to the present invention will be described with reference to FIG. 1 taking a clean room 1 for performing an operation using hydrogen gas among the harmful gases as an example. The harmful gas used here is a generic term for flammable gases such as hydrogen and methane that can cause explosions and fires, and toxic gases such as chlorine and fluorine that can cause toxic accidents to the human body. I do.
[0017]
As shown in FIG. 1, a clean room 1 according to the present embodiment uses a continuous electric furnace in a hydrogen-reducing atmosphere and includes an electric furnace facility H for performing heat treatment such as brazing on semiconductor components in the room. , A clean room main body 2, a circulation unit 3, an outside air intake unit 4, an exhaust unit 5, an inert gas supply unit 6, and a control unit 7. Each component of the clean room 1 is normally driven by a commercial power supply, and is driven by an uninterruptible power supply when the commercial power supply is stopped.
[0018]
The interior of the clean room main body 2 is a component that is filled with clean air from which airborne particles and chemical substances have been removed, and forms a space for performing various dust-free operations. It is designed with a certain level of confidentiality to keep it under pressure. For example, it is basically designed so that the differential pressure between the inside and the outside of the clean room main body 2 is always maintained at a predetermined differential pressure value within a range of about 10 Pa. The predetermined differential pressure value is determined in consideration of cleanliness (a class of cleanliness) required for the specifications of the clean room 1, workability, and economy.
[0019]
The circulation unit 3 is a component for constantly circulating the air inside the clean room main body 2, and includes a circulation duct 31, a high-performance filter 32, and a dust-free blower 34.
[0020]
The circulation duct 31 has both ends connected to the clean room main body 2 via a suction port 31a and an air outlet 31b, and a circulation damper (circulation duct opening / closing device) 33, a blower 34, and a filter 32 are provided inside the duct path. The circulation duct 31 takes in the air of the clean room main body 2 from the suction port 31a side by the operation of the blower 34, and blows out the clean air from the outlet port 31b side. An outside air intake duct 41 to be described later is connected to a portion on the windward side of the filter 32 inside the circulation duct 31.
[0021]
The circulation damper 33 is provided near the suction port 31a of the circulation duct 31, and opens and closes the suction port 31a by changing the angle of the open / close plate 33b. FIG. 2 shows a front view and a side view of the circulation damper. The circulation damper 33 is configured to be able to ventilate in the front direction in FIG. 2A and in the left-right direction in FIG. 2B, and has a rotary cylinder 33a, an opening / closing plate 33b, a rotating shaft 33c, a bracket 33d, and a joint 33e. . The rotary cylinder 33a, the open / close plate 33b, and the rotating shaft 33c constitute a circulation duct opening / closing means. The rotary cylinder 33a is connected to a rotation shaft 33c via a joint 33e. The rotary cylinder 33a is configured to operate by a gas pressure obtained by a nitrogen gas path unit 6 supplied from a liquefied nitrogen tank 61 to be described later via a nitrogen gas valve 63. Further, the rotary cylinder 33a has a configuration in which the pressurizing direction by the nitrogen gas is switched by opening the nitrogen gas on-off valve 63, and the nitrogen gas pressure is applied, and the rotary shaft 33c swings in a range of 90 degrees. Let it.
[0022]
The opening / closing plate 33b is a component for opening and closing the circulation damper 33 in accordance with the swing of the rotating shaft 33c. When the hydrogen gas concentration is equal to or lower than a predetermined concentration value, the circulation damper 33 is opened fully and the hydrogen gas concentration is increased. Is higher than the predetermined density value, the circulation damper 33 is set to a substantially closed state. As shown in FIG. 3, the opening / closing plate 33b is attached to the rotating shaft 33c via a bracket 33d. The bracket 33d is fixed to the vicinity of both edges of the opening / closing plate 33b, and is attached to the rotating shaft 33c with bolts (not shown).
[0023]
As shown in FIG. 1, the filter 32 is provided on the leeward side of the circulation duct 31, and from the air taken in from the suction port 31 a and the outside air intake duct 41, suspended particles or chemical substances that hinder dustless work. Is removed by filtration or static electricity. As the filter 32, one having an optimum material and shape is applied according to the cleanliness suitable for the work performed inside the clean room main body 2, including a filter having a multilayer structure.
[0024]
Also, as shown in FIG. 1, the outside air intake unit 4 is a component for introducing outside air into the clean room main body 2 as new air, and a suction path from the outside air intake duct 41 to the blower 34. Having. A blower 34 is provided on the leeward side of the outside air intake duct 41, and the air from the clean room 1 can be taken into the clean room main body 2 by the operation of the blower 34. A blower that can always maintain the inside of the clean room main body 2 in a positive pressure state with a predetermined differential pressure value with respect to the outside is applied.
[0025]
The exhaust unit 5 is a component for exhausting hydrogen gas (toxic gas) from the inside of the clean room main body 2 as shown in FIG. 1, and includes an exhaust duct 51, an exhaust damper 52, a venturi as shown in FIG. It comprises a pipe 53, a liquefied nitrogen tank 61, a nitrogen gas pipe 62, and a nitrogen gas valve (inert gas valve) 63.
[0026]
The exhaust duct 51 is connected at the ceiling of the clean room main body 2 so as to reliably discharge hydrogen gas in the upper layer inside the clean room main body 2. Specifically, one end of the exhaust duct 51 is connected to the clean room main body 2 through an exhaust port 51 a provided on the ceiling surface of the clean room main body 2. The exhaust damper 52 is provided near the exhaust port 51a, and includes a rotary cylinder 52a, an open / close plate 52b, a rotating shaft 52c, a bracket 52d, and a joint 52e, as in FIGS. The exhaust damper 52 is controlled to be substantially closed when the hydrogen gas concentration is equal to or lower than a predetermined concentration value, and to be completely opened when the hydrogen gas concentration is higher than the predetermined concentration value.
[0027]
The rotary cylinder 52a, the opening / closing plate 52b, and the rotating shaft 52c operate as an exhaust duct opening / closing means, and the rotary cylinder 52a as a driving source is a valve for controlling the gas pressure of the nitrogen gas supplied from the liquefied nitrogen tank 61 shown in FIG. The operation is switched by the operation, and the open / close plate 52b is swung together with the rotating shaft 52c to switch the open / close state of the exhaust damper 52. The rotary shaft 52c is connected to a rotary cylinder 52a via a joint 52e as shown in FIG. The opening / closing plate 52b is attached via a bracket 52d, 52d to a rotating shaft 52c as an opening degree adjusting means.
[0028]
The venturi pipe 53 is provided at the other end of the exhaust port 51a of the exhaust duct 51, as shown in FIG. The venturi tube 53 has a throat portion (53a) having a smaller diameter than the tube portions before and after the duct route, and conical tube portions 53b and 53c connected to the throat portion before and after and having a continuously changing diameter. ing. A nozzle 53d for gas injection is provided at a central position inside the throat portion (53a).
[0029]
Although not shown in detail in FIG. 1, the nozzle 53 d is provided at the center of the throat 53 a of the venturi tube 53, and injects nitrogen gas in the direction of the arrow outside the clean room 1. The venturi tube 53 draws in air from the exhaust port 51a side by creating a negative pressure in the throat portion 53a with respect to the clean room main body 2 by injecting nitrogen gas from the nozzle 53d to the clean room main body 2 and generating an airflow toward the outside of the clean room main body 2. The hydrogen gas (toxic gas containing mixed air) inside the main body 2 is exhausted.
[0030]
The liquefied nitrogen tank 61 is a large tank that stores liquefied nitrogen LN2, and forms an inert gas supply unit together with the nitrogen gas pipe 62. The liquefied nitrogen tank 61 has a decompressor (not shown). The pressure of the vaporized nitrogen gas is adjusted by the depressurizer, and is sent out to the nitrogen gas valve 63 as an inert gas pressure. The nitrogen gas pipe 62 guides the nitrogen gas discharged from the liquefied nitrogen tank 61 through the nitrogen gas valve 63 to the injection nozzle 53d, the rotary cylinder 33a, and the rotary cylinder 52a. The nitrogen gas valve 63 has an electromagnetic valve operated under the control of the control device 71 described later, and switches the open / close state of the nitrogen gas pipe 62 between two modes, a normal mode and an abnormal mode.
[0031]
The normal mode is a mode corresponding to a case where the hydrogen concentration inside the clean room main body 2 is equal to or lower than a predetermined concentration value. In this mode, a nitrogen gas pressure is applied to the rotary cylinder 33a in a direction to open the circulation damper 33, and a nitrogen gas pressure is applied to the rotary cylinder 52a in a direction to close the exhaust damper 52. In this mode, nitrogen gas is not supplied to the nozzle 53d.
[0032]
The abnormal mode is a mode corresponding to a case where the hydrogen concentration inside the clean room main body 2 exceeds a predetermined concentration value. In this mode, a nitrogen gas pressure is applied to the rotary cylinder 33a in a direction to close the circulation damper 33, and a nitrogen gas pressure is applied to the rotary cylinder 52a in a direction to open the exhaust damper 52. In this mode, nitrogen gas is supplied to the nozzle 53d.
[0033]
The control unit 7 is a component that detects and controls the pressure and harmful gas concentration inside the clean room main body 2, and includes a control device 71, a hydrogen gas concentration detector (harmful gas concentration detector) 73, an alarm 74, a return button 75, It has an uninterruptible power supply 76. The hydrogen gas concentration detector 73 measures the hydrogen gas concentration inside the clean room main body 2 and transmits the measured value to the control device 71. The hydrogen gas concentration measuring device 73 is provided near the ceiling of the clean room main body 2 so that the hydrogen gas existing inside the clean room main body 2 can be reliably detected.
[0034]
The control device 71 includes a CPU, a ROM, and a RAM on a drive circuit, and is connected to the components of the clean room 1 for the respective operations. The control device 71 performs various calculations based on the measured value of the hydrogen gas concentration detected by the hydrogen gas concentration detector 73 and controls each component of the system of the clean room 1. The control device 71 switches the mode of the nitrogen gas valve 63 from the normal mode to the abnormal mode when the measured value of the hydrogen gas concentration transmitted from the hydrogen gas concentration detector 73 exceeds a predetermined concentration value. Here, the predetermined concentration value is a concentration value that is naturally set lower than the lower limit of the explosion hydrogen gas concentration, and is set in consideration of worker safety, work efficiency and economy.
[0035]
The alarm 74 warns an operator or a manager by sound or light when the hydrogen gas concentration inside the clean room main body 2 exceeds a predetermined concentration value. The return button 75 is a button operated by an operator to return to the original state when the hydrogen gas concentration inside the clean room main body 2 returns to a predetermined concentration value (normal state) again. The uninterruptible power supply 76 is configured to include an emergency battery, and when a normal commercial power supply is interrupted, control is performed during a blank time until power supply from the emergency private power generator is started. The power can be supplied to the device 71 and the nitrogen gas valve 63. Next, an operation flow of the clean room 1 according to the present invention will be described with reference to FIG. In FIG. 4, a single-line arrow (→) indicates the flow of an electric signal, and a double-line arrow (→) indicates the flow of nitrogen gas.
[0036]
First, the hydrogen gas concentration detector 73 detects and measures the hydrogen gas concentration near the ceiling inside the clean room main body 2 and transmits the measured value to the control device 71. At the normal time when the measured value of the control device 71 does not exceed the predetermined concentration value, the nitrogen gas valve 63 is in the normal mode. At this time, the rotary cylinder 33a of the circulation damper 33 is pressurized to the side that opens the opening and closing plate 33b, and conversely, the rotary cylinder 52a of the exhaust damper 52 is pressurized to the side that closes the opening and closing plate 52b. Thus, the inside of the clean room main body 2 is maintained at a positive pressure against the outside air, including the outside air intake from the outside air intake duct 41, by the suction and discharge action of the blower 34.
[0037]
In the case of the normal mode, the opening / closing plate 52b of the exhaust damper 52 is maintained at such an opening that the air inside the clean room main body 2 always slightly leaks by adjusting the stopper. Thereby, air can be circulated while the inside of the clean room main body 2 is always maintained at a positive pressure from the outside air. As described above, the differential pressure between the inside and the outside of the clean room main body 2 is maintained at a predetermined differential pressure value, and the air inside the clean room main body 2 is stably maintained in a clean state from which suspended particles and chemical substances have been removed. Dripping.
[0038]
On the other hand, when the value measured by the hydrogen gas concentration detector 73 exceeds the predetermined concentration value, the control device 71 switches the nitrogen gas valve 63 to the abnormal mode. At the same time, the control device 71 activates the alarm 74 to warn an operator or the like. Then, by switching the nitrogen gas valve 63, the rotary cylinder 33a pressurizes in a direction to close the open / close plate 33b of the circulation damper 33. Further, the rotary cylinder 52a presses the opening / closing plate 52b of the exhaust damper 52 in a direction in which the opening / closing plate 52b is opened. In addition, nitrogen gas is injected from the injection nozzle 53d toward the outside of the clean room main body 2. Due to this injection, the pressure in the exhaust duct 51 in the venturi pipe 53 is reduced, and the air inside the clean room main body 2 is sucked at the exhaust port 51a side. The sucked hydrogen gas is diluted with the nitrogen gas injected together with the air, and is continuously discharged to the outside of the clean room main body 2.
[0039]
As a result, when the measured value of the hydrogen gas concentration detector 73 inside the clean room main body 2 falls below the predetermined concentration value, the control device 71 stops the warning by the alarm 74. After the warning stops, the operator removes the cause of the increase in the hydrogen gas concentration and then operates the return button 75 to return the control device 71 to the original state. By the operation of returning to the original state, the control device 71 returns the nitrogen gas valve 63 to the normal mode. In this way, the circulation damper 33 is opened, and the exhaust damper 52 is almost closed as described above, so that the normal mode is restored.
[0040]
In the event of a sudden disaster or the like, when the power supply from the commercial power supply to the clean room 1 is stopped together with the occurrence of the above-mentioned abnormal mode, in the case of an emergency, the control unit 71 from the uninterruptible power supply 76 and the nitrogen gas valve 63 Power will be supplied. In the case of this abnormal mode, the required time depends on the battery capacity, but it is desirable to switch to the emergency private power generator in as short a time as possible. The predetermined time here ensures that when the dangerous hydrogen gas rises at a stretch between the time when the commercial power supply is stopped and the time when the power supply by the emergency private power generator is started, the hydrogen gas can be reliably discharged. It is a time zone required in consideration of safety, work efficiency.
[0041]
As described above, in the exhaust system of the clean room 1 according to the present invention, the forced exhaust is automatically performed using the nitrogen gas from the exhaust damper 52 only when the hydrogen gas concentration inside the clean room main body 2 exceeds the predetermined concentration value. By doing so, human errors can be prevented, and the clean room can be easily adapted to the safety of handling hydrogen gas with relatively low initial equipment costs. In addition, the circulation damper 33, the exhaust damper 52, and the venturi tube 53 perform operations required for discharging hydrogen gas using the nitrogen gas pressure as a power source, so that it is not necessary to use explosion-proof specifications. Further, since the hydrogen gas concentration is diluted by the nitrogen gas and discharged to the outside of the clean room main body 2, there is no need to provide explosion-proof equipment around the outside of the clean room 1. Therefore, also from these facts, the clean room 1 can be adapted to the equipment of the hydrogen gas handling specification at a low initial equipment cost.
[0042]
In addition, when the value measured by the hydrogen gas concentration measurement detector 73 exceeds a predetermined concentration value, the controller 71 automatically starts a series of operations for hydrogen gas exhaustion. There is no need to staff. Therefore, the labor cost required for hydrogen gas concentration management (danger management) can be reduced.
[0043]
In addition, even if the power supply from the commercial power supply to the clean room 1 is stopped and a power failure occurs, a program is set to discharge hydrogen gas in preparation for an increase in the concentration of hydrogen gas. It is no longer necessary to constantly arrange the devices. In addition, among the mechanical elements that operate for discharging hydrogen gas, the rotary cylinder 33a, the rotary cylinder 52a, and the venturi tube 53 can be operated at the pressure of nitrogen gas, so that power supply is resumed by emergency private power generation. In the meantime, the power consumption of the safety device can be minimized only by switching the solenoid valve. Thus, the uninterruptible power supply 76 can safely and reliably discharge hydrogen gas until power is supplied from the emergency private power generator. Therefore, high security can be secured with low capital investment and cost.
[0044]
Furthermore, in the clean room 1 according to the present invention, the opening degree of the circulation duct 33 and the exhaust duct 52 can be adjusted by the stoppers of the brackets 33d and 52d, so that the overflow for adjusting the differential pressure between the inside and the outside of the clean room main body 2 is performed. There is no need to have a special mechanism. Therefore, the clean room 1 can be manufactured more easily and inexpensively.
[0045]
The above-described combinations, structures, and examples of toxic gases according to the present invention are not limited to the examples. The clean room 1 according to the present invention may manage the concentration of a combustible gas such as methane, or a toxic gas such as chlorine or fluorine, in addition to the hydrogen gas. Here, when controlling the concentration of harmful gases such as chlorine and hydrofluoric acid having a higher specific gravity than air in the clean room 1, the harmful gas concentration detector or measuring device is arranged near the floor, and the exhaust duct is arranged near the floor. Sometimes it connects. As described above, the positions at which the harmful gas concentration detector or measuring device and the exhaust duct are attached are appropriately determined in accordance with the physical properties of the harmful gas whose concentration is to be controlled. Here, when managing the concentration of the toxic gas, it is preferable to set the predetermined concentration value in consideration of the safety and the working efficiency of the worker on condition that the predetermined concentration value is equal to or lower than the permissible concentration of the corresponding gas.
[0046]
Further, the clean room 1 according to the present invention may manage a plurality of harmful gas concentrations.
[0047]
Further, in the clean room 1 according to the present invention, as the inert gas, a rare gas such as helium, argon, neon, or xenon may be applied, or carbon dioxide may be applied. The inert gas is appropriately selected in consideration of safety and economy from among gases having extremely low reactivity at normal temperature and normal pressure.
[0048]
Further, in the clean room 1 according to the present invention, a general differential pressure damper may be provided in the clean room main body 2. In this case, when the differential pressure exceeds a predetermined differential pressure value, the differential pressure can be adjusted by opening the differential pressure damper. At the same time, in the clean room 1 according to the present invention, the opening / closing plate 52b is always kept slightly open by the stopper function of the bracket 52d of the exhaust damper 52 as an effect of discharging minute hydrogen gas in the normal mode. The structure may be such that hydrogen in the upper layer is always caused to flow and exhausted. The opening degree of the circulation damper 33 and the exhaust damper 52 in the normal state and at the time of discharging the hydrogen gas is a design item related to the positive pressure, and may be appropriately determined.
[0049]
[Effects of the present invention]
As described above, according to the present invention, the harmful gas concentration in the clean room main body is managed by the harmful gas concentration detector and the control device, and when the harmful gas concentration exceeds a predetermined concentration value, the control device is disabled. By controlling the active gas valve, the circulation duct is closed and the exhaust duct is opened. Therefore, when the circulation duct is substantially closed by the inert gas pressure, the circulation of the air in the clean room main body is stopped or extremely reduced. Then, the exhaust duct is opened by the inert gas pressure, and an inert gas is injected from the inside of the Venturi tube toward the outside of the clean room main body. Due to the injection of the inert gas, a large pressure difference is generated between the inside of the clean room main body and the Venturi tube, so that the contaminated air inside the clean room main body is discharged, and accordingly, the harmful gas concentration is efficiently discharged. At this time, since the outside air intake duct is always open, by taking in outside air from this outside air intake duct, the inside of the clean room main body is maintained at a positive pressure even during exhaust.
[0050]
The driving force of the harmful gas discharging operation is performed by injecting an inert gas from the inside of the Venturi tube. The driving operation of the circulation duct and the exhaust duct is also performed at an inert gas pressure. Therefore, unlike the case where an electric electric motor fan is provided, these components do not need to have expensive explosion-proof specifications. Further, since the harmful gas is almost diluted with the inert gas and discharged, there is almost no need to provide processing equipment for explosion proof and gas proof outside the clean room. However, specific substances specified in environmental standards are required separately. These facts can also deal with the handling of harmful gases inside the clean room main body with low initial equipment costs.
[0051]
In addition, since the discharge of harmful gas is automatically performed for 24 hours by a control device connected to the harmful gas concentration detector, the harmful gas concentration increases even when no resident personnel are assigned except during work. Can also handle crisis management. These facts also make it possible to make the management of the concentration of harmful gas unmanned and maintain it at low cost. For example, when the concentration of the harmful gas inside the clean room body exceeds a predetermined concentration value, the control means opens an inert gas valve on the side where the inert gas is injected from the Venturi pipe, and then vents the Venturi by the injection of the inert gas. When the inside of the pipe becomes a negative pressure with respect to the inside of the clean room, the internal air is pulled, the fluid force in the harmful gas discharge path is generated, and the exhaust is smoothly performed.
[0052]
Further, according to the present invention, even when the concentration of harmful gas is repeatedly increased when a power failure occurs due to an accident or disaster, the harmful gas can be discharged safely and reliably because the power system is independent. At this time, the mechanical components among the components driven for harmful gas discharge are the exhaust duct and the circulation duct, which are mainly driven by the inert gas pressure. During this time, harmful gas can be discharged with a minimum amount of reserve power. Therefore, at the time of a power failure, harmful gas can be discharged from the clean room main body with high reliability. Therefore, it is not necessary to constantly arrange personnel in preparation for a power failure or the like in an accident or the like, and it is possible to control the concentration of harmful gas inside the clean room with high safety and at low cost.
[0053]
Further, according to the present invention, by allowing at least one of the circulation duct opening / closing means and the exhaust duct opening / closing means to be adjusted by the opening degree adjusting means, the flow rate of the air taken in by the circulation duct and the exhaust by the exhaust duct are exhausted. The air flow can be adjusted. As a result, it is possible to adjust the pressure difference between the inside and the outside of the clean room as a component for discharging harmful gas. Therefore, since there is no need to provide a component for adjusting the differential pressure, a clean room capable of controlling the concentration of harmful gas can be provided more safely and at lower cost. In addition, by reducing the load of the air conditioner on the clean room equipment, it is possible to reduce the initial equipment cost for the clean room corresponding to the use of harmful gas. In addition, by automating the exhaust, human error is eliminated and safety is ensured as compared with the manual type. In addition, it can be automatically operated even in the event of a power failure during a disaster such as a typhoon or an earthquake.
[Brief description of the drawings]
FIG. 1 is a schematic view of a clean room 1 according to the present invention.
FIG. 2 is a side sectional side view (a) and a sectional front view (b) of a circulation damper 33 and an exhaust damper 52 applied to a clean room 1.
FIG. 3 is a side sectional view of the vicinity of rotary type cylinders 33a and 52a of the circulation damper 33 and the exhaust damper 52.
FIG. 4 is a block diagram of a clean room 1 according to the present invention.
[Explanation of symbols]
1 clean room
2 Clean room body
3 Circulation unit
4 Outside air intake unit
5 Exhaust unit
7 Control unit
31 Circulation duct
32 filters
33 Circulation damper
33a Rotary cylinder (circulation duct opening / closing means)
33d, 52d bracket (opening adjustment means)
33b Opening / closing plate (circulation duct opening / closing means)
33c Rotary shaft (circulation duct opening / closing means)
34 blower
41 Outside air intake duct
42 outside air intake blower
51 Exhaust duct
52 Exhaust damper
52a Rotary cylinder (exhaust duct opening / closing means)
52b opening / closing plate (exhaust duct opening / closing means)
52c Rotary shaft (exhaust duct opening / closing means)
53 Venturi tube
53a throat part
53d nozzle
55 Return button
61 Liquefied nitrogen tank (inert gas supply device)
62 Nitrogen gas pipe (inert gas supply device)
63 Nitrogen gas valve (inert gas valve)
71 Controller
73 Hydrogen gas concentration detector (Hazardous gas concentration detector)
74 alarm
76 Uninterruptible power supply
LN2 Liquefied nitrogen

Claims (3)

A clean room body where the inside is kept at a positive pressure with respect to the outside,
Both ends are connected to the clean room body, a circulation duct that sucks air inside the clean room body from one end and blows air from the other end,
A filter provided inside the circulation duct path, for filtering the air;
A circulation duct opening / closing means for substantially closing one end of the circulation duct by the pressure of the inert gas,
An external air intake duct connected to the circulation duct intermediate portion between the circulation duct opening / closing means and the filter, and taking air outside the clean room main body into the circulation duct intermediate portion;
An exhaust duct having one end connected to the clean room main body, the other end having a venturi pipe for injecting the inert gas inside the duct, and exhausting the air inside the clean room main body to the outside,
Exhaust duct opening and closing means for opening one end of the exhaust duct by the pressure of the inert gas,
An inert gas supply system that supplies the inert gas to the circulation duct opening / closing unit, the exhaust duct opening / closing unit, and the venturi pipe via an inert gas valve;
A control unit having a detector for detecting the concentration of harmful gas inside the clean room body and a measuring device for measuring the concentration,
When the harmful gas concentration in the clean room main body exceeds a predetermined concentration value, the control unit substantially closes the circulation duct opening / closing means, opens the exhaust duct opening / closing means, and the venturi pipe injects the inert gas. A clean room exhaust system having a control device for opening the inert gas valve on a side thereof. The clean room exhaust system according to claim 1, further comprising an uninterruptible power supply for supplying power to the control device and the inert gas valve, wherein the control device opens the inert gas valve for a predetermined time when a power failure occurs. . The clean room exhaust system according to claim 1 or 2, further comprising an opening adjustment unit that adjusts an opening of at least one of the circulation duct opening / closing unit and the exhaust duct opening / closing unit.

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