Patent Application
20240408264
The present invention relates to a decontamination system for decontaminating an air supply space constructed between an air filter for converting air supplied to an inside of a work room which maintains a sterile environment into clean air, and a straightening plate for straightening the clean air and supplying the straightened clean air to the inside of the work room.
In works performed in a clean atmosphere, e.g., a work at a manufacturing stage of pharmaceutical products, or a work at a manufacturing stage of semiconductors or electronic components, the work is performed in a clean working environment which maintained an inside thereof in sterile isolator and dust-free conditions so that no contaminant enters from an external environment. As such a working environment, a clean room is generally used. In this clean room, an operator wearing dust-free clothes works. However, in order to increase a sterility assurance level and a dust-free assurance level, a still higher-level clean area is constructed in the clean room to perform the works.
One method of constructing such a higher-level clean area is to use an isolator or glove box (hereinafter collectively referred to as an “isolator”). This isolator uses a chamber sealed from the external environment, the operator works via a work glove or the like from outside this chamber. In the chamber of these isolators, a unidirectional laminar flow of clean air is flowed from an upper side to a lower side to maintain a clean environment in the chamber.
Moreover, a Restricted Access Barrier System (RABS) is used as another method of constructing a higher-level clean area. This RABS is configured to provide a area surrounded by a wall surface of which a lower portion is opened at a portion in the clean room, a unidirectional laminar flow of clean air is flowed into the inside thereof from an upper side to a lower side, and operator's strict access restrictions are realized. In this RABS, the operator works via a work glove or the like provided in the wall surface.
Moreover, in GMP (Good Manufacturing Practice; Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients), which summarizes requirements for manufacturing pharmaceutical products, a requirement for wind speed distribution with respect to clean air flow in the isolator and RABS has been stricter.
In the chamber of the isolator or the work room of RABS, a method of flowing the clean air from an upper side to a lower side is generally to install a punching plate on a ceiling portion in the chamber, through which the clean air that has passed through an air filter such as a HEPA filter is supplied from the upper side and exhausted downward. However, the opening of this punching plate has a pore size of several millimeters, and the Reynolds number of the airflow passing through is on the order of the fourth power of 10. In this state, the airflow becomes a turbulent flow from a stage of passing through the fine pores of the punching plate, and therefore a unidirectional steady flow flowing from the upper side to the lower side cannot be formed.
Therefore, instead of the punching plate, a straightening plate covered with a screen mesh having an opening of approximately 30 to 200 μm is used. The straightening plate is configured to “straighten” air, that is to form a substantially spatially unidirectional steady flow of air. In accordance with this method, the Reynolds number of the airflow passing through the screen mesh is approximately 2 to 10, and a unidirectional steady flow that is substantially a laminar flow can be formed.
On the other hand, hydrogen peroxide gas has been widely adopted into decontamination in the chamber of the isolator or the work room of RABS (hereinafter referred to as a “room targeted to be decontaminated”). Advantageously, hydrogen peroxide gas has a strong sterilization effect, and is inexpensively available and effectively utilized as an environmentally-friendly decontamination gas that is ultimately decomposed into oxygen and water. In addition, the following patent document 1 describes that the decontamination effect by hydrogen peroxide is provided by a condensed film of a hydrogen peroxide solution that condenses on the surface of an object to be decontaminated.
The inventors of the present invention have found that a fine mist of hydrogen peroxide solution (hereinafter referred to as a “hydrogen peroxide mist”), instead of a hydrogen peroxide gas, is supplied to a room targeted to be decontaminated, thereby achieving efficient decontamination using a least possible amount of decontamination agent, and have proposed the technique as described in Patent Literature 2 listed below. After that, decontamination using hydrogen peroxide mist has spread worldwide.
When decontaminating a room targeted to be decontaminated using hydrogen peroxide mist, the hydrogen peroxide mist is basically supplied to the room targeted to be decontaminated. At this time, there has been a problem that a space between an air filter and a straightening plate above the room targeted to be decontaminated (hereinafter referred to as “air supply space”) is not sufficiently decontaminated, since it is principle that air is not circulated during the decontamination. In other words, the hydrogen peroxide mist discharged to the room targeted to be decontaminated cannot pass through the screen mesh and therefore cannot reach the air supply space. Moreover, there has been a problem that even if the hydrogen peroxide mist is directly supplied to the air supply space, dew condensation occurs on a surface of the screen mesh.
In order to solve this problem, it is considered to construct a circulation path of a hydrogen peroxide mist, from a hydrogen peroxide mist generating device to the room targeted to be decontaminated through the air supply space, and returning from the room targeted to be decontaminated to the hydrogen peroxide mist generating device. However, in this method, there has been a problem that a capacity of the circulation path is large, the amount of consumption of the hydrogen peroxide is increased, and decontamination cycle time is significantly extended.
Moreover, the inventors have proposed to additionally provide a hydrogen peroxide mist generating device and a mist dispersion/diffusion device in the air supply space in Patent Literature 3 listed below. Herein, the mist dispersion/diffusion device is configured with an ultrasonic vibration plate and to disperse and diffuse the hydrogen peroxide mist by acting acoustic radiation pressure due to an ultrasonic vibration on the hydrogen peroxide mist. However, in this method, there is also a problem that a hydrogen peroxide mist generating device must be installed in both the room targeted to be decontaminated and the air supply space, and the mist dispersion/diffusion device must also be installed in the air supply space, and therefore a mechanism thereof is complexed. Furthermore, in a small-scaled isolator, the air supply space may be small, and therefore it may be difficult to install the hydrogen peroxide mist generating device and the like therein.
Accordingly, the present invention has been made in order to solve the problems described above, and an object of the present invention is to provide a decontamination system having a simple structure using a decontamination agent supplied to a room targeted to be decontaminated without additionally providing a decontamination agent discharging device or the like in a space (air supply space) between an air filter and a straightening plate, the decontamination system being capable of efficiently decontaminating the air supply space in a short period of time.
To solve the aforementioned problem, inventors of the present invention have carried out an extended investigation to find the advantage of using a decontamination agent transfer device configured to suction, discharge, or circulate decontamination mist between the room targeted to be decontaminated and the air supply space. Based on that technique, the present invention has been accomplished.
Specifically, a decontamination system according to the present invention is, according to description in claim 1,
Moreover, the present invention is, according to description in claim 2, the decontamination system according to claim 1, characterized in that
Furthermore, the present invention is, according to description in claim 3, the decontamination system according to claim 1 or 2, characterized in that:
The reference signs in the parentheses for each of the above-described means indicate a correspondence relationship with concrete means described in embodiments described below.
According to the above-described configuration, the decontamination system is a system for decontaminating an air supply space constructed between an air filter for converting air supplied to an inside of a work room which maintains a sterile environment into clean air, and a straightening plate for straightening the clean air and supplying the straightened clean air to the inside of the work room. The decontamination system includes a decontamination agent discharging device provided in a work room, and a decontamination agent transfer device provided in the air supply space. When decontaminating an inside of the work room, the decontamination agent discharging device is operated to discharge the decontamination agent to the inside of the work room, and the decontamination agent transfer device is operated to suction, discharge, or circulate the decontamination agent between the work room and the air supply space. Consequently, the air supply space can be decontaminated as well as the work room.
Consequently, it is possible to provide a decontamination system having a simple structure using a decontamination agent supplied to a room targeted to be decontaminated without additionally providing a decontamination agent discharging device or the like in a space (air supply space) between an air filter and a straightening plate, the decontamination system being capable of efficiently decontaminating the air supply space in a short period of time.
Moreover, according to the above-described configuration, the straightening plate may include one or more porous sheets for straightening the clean air. Moreover, the decontamination agent transfer device may include an air duct having one end portion as a suction port and the other end portion as a discharge port, and an air-blowing fan provided inside the air duct. This decontamination agent transfer device is disposed so that the suction port is in contact with the porous sheet at an inside side of the air supply space. Consequently, the above-described operational advantageous effects can more specifically and more effectively be demonstrated.
Moreover, according to the above-described configuration, the decontamination agent may be decontamination mist in an aerosol state. Moreover, the decontamination agent transfer device discharges the decontamination mist discharged to the inside of the work room from the decontamination agent discharging device to an inside of the air supply space. Consequently, the above-described operational advantageous effects can more specifically and more effectively be demonstrated.
First, prior to describing a decontamination method using a decontamination system according to the present invention, a conventional decontamination method using a hydrogen peroxide mist will now be described. In the conventional decontamination method, and the decontamination method using the decontamination system according to the present invention both illustrated below, a hydrogen peroxide solution is used as a decontamination agent. Although a concentration of the hydrogen peroxide solution to be used is not limited in particular, in general, it is preferable to use the hydrogen peroxide solution of 30% to 35% by weight in consideration of handling of a hazardous material or the like. Moreover, the decontamination agent used in the conventional decontamination method, and the decontamination method using the decontamination system according to the present invention is not limited to the hydrogen peroxide solution, and may be any liquid decontamination agent, such as an aqueous solution of peracetic acid.
In the present invention, the term “mist” is broadly interpreted as a state of a liquid droplet of a decontamination agent refined and floating in the air, a state of a gas and a liquid droplet of a decontamination agent in mixture, a state of the decontamination agent to repeat the change in phase between condensation and evaporation of a gas and a droplet, and the like. In terms of particle size as well, the mist is also broadly interpreted to include mists, fogs, and liquid droplets, which can be subclassified.
The air supply mechanism 20 includes an air supply blower 21 for supplying outside air into the chamber 10, an air supply filter unit 22 for filtering the air supplied from this air supply blower 21 and converting the air into clean air, and a straightening plate 23 disposed at a ceiling portion in a chamber 10 for straightening the clean air filtered by the air supply filter unit 22 and supplying the clean air into the chamber 10. In the present invention, a space between the air supply filter unit 22 and the straightening plate 23 illustrated in
Inside the mount B, the exhaust mechanism 30 includes an exhaust port for exhausting the air in the chamber 10, an exhaust filter unit for filtering air to be exhausted, and an air exhaust blower for exhausting the air filtered by the exhaust filter unit (all not illustrated).
Herein, the straightening plate 23 will be described. The straightening plate 23 is constructed by tensely attaching two screen meshes 23a, 23b to a frame body 24. It is to be noted that the number screen meshes constructing the straightening plate 23 may not be particularly limited, and may be one or more. Moreover, the screen meshes 23a, 23b are generally woven fabrics made of synthetic filament yarns, and countless fine pores that communicates between front and back surfaces are formed by gaps between warp and weft yarns of this woven fabric. Consequently, a flow of air passing through the straightening plate 23 is straightened by these countless fine pores, thereby forming a unidirectional steady flow of clean air traveling from an upper side to a lower side inside the chamber.
The synthetic filament yarns forming these screen meshes 23a, 23b preferably have a filament diameter of 30 to 200 μm and preferably have an opening of 30 to 200 μm. Moreover, the screen meshes 23a, 23b may be made of any material, and polyethylene gauze is generally used in many cases. Thus, in the straightening plate 23, the openings of the screen meshes can be made as fine as approximately 30 to 200 μm. Consequently, the Reynolds number of the airflow passing through the screen meshes is approximately 2 to 10, and a unidirectional steady flow that is substantially a laminar flow can be formed.
Moreover, in
It is to be noted that a mist generating mechanism of the mist discharging device 40 is not particularly limited. For example, the mist generating mechanism may be a single-fluid spray nozzle, a piezo high-pressure jet device, an immersion type ultrasonic atomizer, a disk-type atomizer, a disk-mesh type atomizer, or the like for directly forming the solution into mist. Alternatively, it may be an ejector, two-fluid spray nozzle, or the like for forming the solution into mist by using a high-pressure air or the like. On the other hand, output and mist discharging capacity, etc. of the mist discharging device 40 may be appropriately set, including the number thereof, in dependence with a volume, a shape, and the like of a room targeted to be decontaminated, such as a chamber.
Furthermore, a mist dispersion/diffusion device may be additionally provided in addition to the mist discharging device 40. The mist dispersion/diffusion device is configured with an ultrasonic vibration plate and to disperse and diffuse the hydrogen peroxide mist, discharged by the mist discharging device 40, by acting acoustic radiation pressure due to an ultrasonic vibration on the hydrogen peroxide mist.
In these configurations, the decontamination effect inside the chamber 10 can be effectively obtained in accordance with the decontamination operation illustrated in
Therefore, the decontamination system according to the present invention will now be described based on the embodiments.
In
The decontamination agent transfer device 60 is provided in a state of being placed on the straightening plate 23.
It is to be noted that a position of the decontamination agent transfer device 60 in the air supply space 50 is not particularly limited, and it may be disposed in consideration of: a relationship with a position of the mist discharging device 40 provided inside the chamber 10; a position of an important sterilization process, work (pass line), and the like in the isolator device; and a state of dispersion and diffusion of a hydrogen peroxide mist inside the air supply space 50. Moreover, the number of decontamination agent transfer devices 60 is not be limited to one, and may be appropriately set depending on a relationship with a volume of the air supply space 50, and the like.
Herein, a structure of the decontamination agent transfer device 60 will now be described.
Next, an action of the decontamination agent transfer device 60 in decontamination and aeration operations will be described. First, an operation for decontaminating the inside of the chamber 10 and the inside of the air supply space 50 will be described.
In
In addition, since the suction port 62 of the decontamination agent transfer device 60 is in contact with the screen mesh 23a, the hydrogen peroxide mist inside the chamber 10 is sucked through the two screen meshes 23a, 23b of the straightening plate 23. Accordingly, it is preferable to adjust the output of the air-blowing fan 64 with respect to the number of screen meshes and the openings in accordance with the capacity of the air supply space 50. By maintaining such a state, the inside of the chamber 10 and the inside of the air supply space 50 can be efficiently decontaminated in a short period of time.
Next, an operation of performing aeration after decontaminating the inside of the chamber 10 and the inside of the air supply space 50 will be described.
In
In this state, clean air is supplied from the air supply blower 21 to the inside of the air supply space 50 through the air supply filter unit 22, and aeration is performed. Moreover, inside the air supply space 50, the clean air is flowing into the inside of the chamber 10 through the two screen meshes 23a, 23b of the straightening plate 23 due to pressurization acted by the air supply blower 21 and the suction acted by the air exhaust blower that are operating simultaneously. It is to be noted that the clean air flows into portions of the aeration and the screen meshes 23a, 23b with which the suction port 62 of the decontamination agent transfer device 60 is in contact, the aeration is also performed as in other portions.
The clean air flowing into the inside of the chamber 10 aerates the inside of the chamber 10. The air inside the chamber 10 is introduced into an external hydrogen peroxide decomposition catalyst device (not illustrated) from the air exhaust blower through the exhaust filter unit. By maintaining such a state, the inside of the chamber 10 and the inside of the air supply space 50 can be efficiently aerated in a short period of time.
As described above, according to the present invention, it is possible to provide the decontamination system having a simple structure using a decontamination agent supplied to a room targeted to be decontaminated without additionally providing a decontamination agent discharging device or the like in a space (air supply space) between an air filter and a straightening plate, the decontamination system being capable of efficiently decontaminating the air supply space in a short period of time.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-173858 | Oct 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/038883 | 10/19/2022 | WO |
