JPH0479956A - Cleaning system of clean room - Google Patents

Abstract

PURPOSE:To achieve complete sterilization and also promptly restore a sterile state after stopping operation of a system for a long period by supplying ozones of high density to the inside of a clean room for ozone fumigation, and then supplying ozones of low density. CONSTITUTION:In a circuit for operating a clean room, ozones of low density are supplied by an ozone generator 61 to air introduced into an air cleaner 6 by means of actuation of the blower of a line R5 and the air is fed to an air conditioner 4 via a heater 5 and allowed to pass through a hepafilter 2 via a filter unit 3 and then fed into the clean room. Air discharged from the inside of the clean room is refed and circulated into the air cleaner 6 by a line R4 and is also circulated to the air conditioner 4 through a line R2. Using a circuit for ozone fumigation, ozones are directly added by an ozone generator 7 to the air to which ozones of low density are added by the ozone generator 61 and the air having ozones of high density is fed into the clean room 1 through lines R6 and R7 whereby the clean room 1 is fumigated with ions.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a clean room cleaning system, and more particularly to a clean room cleaning system that uses ozone fumigation to make the interior of the clean room sterile. (Conventional technology and problems to be solved) So-called clean rooms are used in various fields as clean rooms (sterile rooms) with as few particles (including microorganisms) as possible, and are used for aseptic filling of canned goods, drinks, etc. This system is indispensable in the food and beverage industry, semiconductor and pharmaceutical manufacturing, etc. Incidentally, even today, when canning technology has advanced, the commonly used sterilization technology for canned food is a method in which food is filled and sealed in a container and then heated and sterilized from the outside (retort sterilization method). This retort sterilization method uses steam or hot water as a heating medium. Heat sterilization of canned goods targets bacterial spores, which are highly heat-resistant among microorganisms, and is generally used for low-acid beverages (oolong tea, coffee, etc.). (tea, soup, sauce, etc.) If it's canned, it varies depending on the can type. High-temperature and long-term sterilization is performed at a temperature of approximately 110-120° C. for 15-60 minutes or more. Generally, bacterial spores do not die even if heated at temperatures below 100°C for quite a long time, but the higher the heating temperature, the less their heat resistance becomes, and when the temperature rises above 130°C, they die instantly. Applying this principle, various new sterilization techniques have been developed that are different from the conventional methods of sterilizing at high temperatures of 130° C. or higher for short periods of time. For example, as an aseptic filling method for canned goods, the container is sterilized for 10 seconds in saturated steam of 3 kg/cm2 or 140°C or higher, and the contents, which have been sterilized at high temperature for a short time, are then filled and sealed in the sterilized can under aseptic conditions. methods are being tried. However, equipment that can withstand sterilization under such high pressure is bulky and expensive, so in recent years, simple aseptic filling systems have been developed, such as the Dole method (for example, the Dole method has been put into practical use). Packaging food technology jp, 3
05-318 (1979)). This method is called a two-step method, and consists of a part that heat-sterilizes the food and a part that aseptically fills and seals the food. This method involves aseptically filling the containers and sealing them with can lids that have also been sterilized using superheated steam. According to this Dole method, the contents are sterilized at high temperature for a short time, then
Since it is filled after being cooled to room temperature, it has better flavor and color tone than the conventional retort method. However, the can itself is heated by superheated steam until it is heated in the system (filler, seamer) until it is filled with filler, and the can itself is hot, and the can lid is also exposed to superheated steam and becomes hot until just before it is seamed. (Furthermore, the filling chamber is also under superheated steam and the filling atmosphere temperature is high.) Therefore, only metal can be used as the container material. In addition, contact with hot cans, can lids, and superheated atmosphere during filling and immediately after sealing causes heat exchange with the contents, resulting in the contents being heated again, which is particularly likely to cause flavor deterioration. The drawback is that it is still unsuitable for food and beverages. Therefore, in aseptic filling of food and beverages, from the point of view of flavor, it is desirable to have a system that can be filled and sealed at room temperature, separate from the sterilization process of container materials. On the other hand, conventional clean room cleaning systems have been equipped with Hepa filters (HEPA filters) at the clean room entrance.
A filter; dustproof efficiency is Q, 99.9 with 3 μm particles
A well-known method is to install a high-efficiency filter (with a high efficiency of 7% or more) through which the air passes through to collect bacteria and particulates, and to supply clean air maintained at an appropriate temperature and humidity into the clean room. Used for aseptic filling, etc. However, with this system, it is possible to maintain the inside of the clean room in a sterile state, but in order to return to a sterile state after a long-term suspension of operation (power outage, boiler inspection, ream, etc.), a bacterial test is also required. It takes about 4 days (including 4 days), and the start-up is slow.As a result, it is necessary to constantly supply clean air through a filter into the clean room to maintain a sterile state even during the downtime, making the entire system costly. It has the disadvantage of becoming. Furthermore, there is no way to sterilize bacteria that adhere to the walls, ceiling, equipment, etc. in a clean room, so there is no complete sterilization ability, and PET
It is not suitable for applications such as aseptic filling of canned goods, which requires stricter sterilization than bottles. The purpose of the present invention is to solve the above-mentioned problems of the prior art and provide a new lean room cleaning system that can perform complete sterilization and quickly return to a sterile state after a long period of suspension of operation. It is something to do. (Means for Solving the Problems) In order to solve the above problems, the present inventors have conducted intensive research on a new lean room cleaning system that can quickly complete sterilization and has a sterilization effect even during normal operation. As a result of repeated research, we focused on the use of ozone's bactericidal effect,
A clean room cleaning system that uses ozone fumigation ("ozone fumigation" refers to supplying highly concentrated ozone air into a clean room, exhausting it, forcing it to circulate, and sterilizing the inside of the clean room at a humidity of 70% or more.) This invention has been developed and the present invention has been made here. That is, the present invention includes an ozone fumigation circuit that supplies high-concentration ozone into a clean room, and a clean room operation circuit that supplies low-concentration ozone into the clean room through a filter provided at the clean room entrance. Abstract: A clean room cleaning system characterized by supplying high concentration ozone into the clean room to perform ozone fumigation, and then supplying low concentration ozone into the clean room to maintain the clean room in a sterile state. It is something. An aspect of the present invention is a clean room cleaning system in which high concentration ozone is supplied directly into the clean room without going through the filter, a clean room cleaning system in which the filter is a hepa filter; Ozone fumigation is performed at an ozone concentration of 20 to 200 ppm and a sterilization time of 1 to 10 hours, and clean room operation is performed at an ozone concentration of 0. It can be a clean room cleaning system that performs cleaning at about 5 ppm of O. In addition, it can be used as a cleaning system for a clean room where the clean room is a room for aseptic filling of canned goods.Furthermore, by changing the effective area of the filter, the filler area and the seamer area can be separated from each other in the clean room space. , and other spaces can be used as a clean room cleaning system that maintains different cleanliness classes from each other. The present invention will be explained in more detail below. (Function) Taking the above-mentioned circumstances into consideration, the present invention has developed a new lean room cleaning system that can completely sterilize and maintain any class of sterility. It is equipped with an ozone fumigation circuit that supplies ozone and a clean room operation circuit that supplies low-concentration ozone into the clean room through a filter installed at the clean room entrance. The former ozone fumigation circuit introduces high-concentration ozone into the clean room, and by uniformizing the ozone concentration in the clean room and forcibly lubricating it, it prevents it from adhering to walls, ceilings, floors, and board surfaces in the clean room. It is possible to completely sterilize all bacteria that are present in the air in a short period of time, and to return to a sterile state in a short period of time after a long period of operation stoppage. After that, the latter clean room operating circuit supplies low-concentration ozone through the filter into the completely sterilized clean room to sterilize the microorganisms that were collected on the filter side during the long-term operation stoppage. Since the operation is performed while forcing ozone to circulate, microorganisms such as floating bacteria and fallen bacteria that are brought into the clean room by operators etc. are quickly discharged from the clean room, and any remaining microorganisms that are not discharged are also prevented from growing. can maintain sterile conditions in the clean room. The cleanliness of bio-clean rooms is defined by standards (National Aeronautics and Space Administration standards) for various classes. Class 100 means that the cumulative number of particles with a particle size of 0.5μ or larger is 100 particles/ft3 or less, and class 10000 means that the cumulative number of particles with a particle size of 0.5μ or larger is 1000 particles/ft3.
It is in a state of 0 pieces/ft3 or less. In the case of aseptic filling of canned goods, a cleaning system that has sufficient sterilization effect against ozone-resistant bacterial spores and can completely sterilize non-spore-forming bacteria is required, but simply adding ozone to the clean room is not practical. It cannot be said that it is a typical system. In other words, it is dangerous to carry out work such as filling canned goods while constantly supplying high-concentration ozone into a clean room, so thorough consideration is required, as well as the corrosion resistance of contact parts. consideration must be given. Therefore, with ozone fumigation, it is recommended that the sterilization process be performed so that the surface sterilization conditions in the clean room are at least ID (sterilization conditions that reduce the number of viable bacteria to 1/10).
Preferably, it is practical and effective to perform ozone fumigation at an ozone concentration of 20 to 20 oppm, a sterilization time of 1 to 10 hours, and a humidity of 70% or more. That is, 200ppm
At higher ozone concentrations, only machines with high corrosion resistance can be used due to the strong oxidizing power, and below 20pp+i, sterilization takes a long time. is not completed and is not practical. In addition, regarding the introduction of ozone during subsequent operation, it is possible to sterilize non-spore-forming microorganisms collected on the inlet side of the filter, and it is also possible to sterilize non-spore-forming microorganisms collected on the inlet side of the filter. It is sufficient to use ozone at a low concentration (0.02 ppm or more) that suppresses growth. Generally, the concentration of ozone gas in the natural world is high in the ground air, on the coast, in mountain forests, etc., and is 0.01 to 0.04 ppr.
n exists, and the ozone concentration in the sky increases to 12,000
At altitudes above +++, ozone exists at 1 to 2 ppm, but for human health reasons, the permissible concentration of ozone is 0.1 ppm.
It is recommended by the Japanese Society of Hygiene that it should be ppm (daily average value during working hours). Therefore, considering the sterilization effect and the effect on the human body, the low concentration of ozone is 0.05
From the viewpoint of sterilization effect, it is preferable to set the amount to 0.1 ppm. Furthermore, if the space inside the clean room is divided into a work area where workers enter and work, and a non-work area where it is extremely difficult to be contaminated with bacteria brought into the clean room by workers entering the room, It is best to maintain each area in a different class of sterile conditions, and for this purpose, each divided area should be equipped with a Hepa filter, and its effective area should be changed to separate working areas and non-working areas without Ozone-kun's assistance. It is desirable for equipment to maintain sterile conditions in each area.

[Left below]

(Example) Examples of the present invention are shown below. FIG. 1 shows an example of the flow of the cleaning system of the present invention. In the figure, 1 is a clean room (sterile room), and HEPA filters 2 are provided at appropriate locations. Here, Hepafilter is a high-performance filter that is made by folding a filter with micropores of approximately 0.3 μm into a multi-layered structure.It can collect microorganisms, and by changing its size (effective area), it can be You can change your degree status into classes of various levels. A clean room operation line that supplies low concentration ozone into the clean room is connected to the HEPA filter 2. Specifically, the HEPA filter 2 is connected to an air handling unit (air conditioner) 4 via a line R having a filter unit (medium-performance filter that removes large dust particles in advance) 3, and this air handling unit 4 is connected to one side. It is directly connected to the clean room 1 via line R2, and on the other hand, an air purifier 6 is connected via line R3 having a heater 5. A first ozone generator 6□ is added to this air cleaner 6. The first ozone generator 6□ is a device that adds ozone to the air cleaner 6 and supplies air containing low concentration of ozone to the line R3. This air cleaner 6 is directly connected to the side wall of the clean room 1 through a line R4, and is also connected to a line R6 that introduces the atmosphere. In this lean room operation circuit, the first ozone generator 61 supplies and mixes ozone at a predetermined low concentration to the air introduced into the air cleaner 6 by operating the blower in line R5, and this air is The air is sent to the air handling unit 4 via the heater 5, passes through the Hepa filter 2 via the filter unit 3, and is supplied into the clean room. The air discharged from the clean room is again circulated and supplied to the air cleaner 6 via line R4, and on the other hand, is circulated and supplied to the air handling unit 4 via line R2. On the other hand, in the ozone fumigation circuit, the second ozone generator 7 is directly connected to the line R1, and this line R3 is directly connected to the wall surface of the clean room 1 facing R4 by the line Rs. The second ozone generator 7 is for supplying highly concentrated ozone gas directly to the line R3. This line R6 is specially provided with a line R7 equipped with a humidifier 8 for humidifying the inside of the clean room, so that mixed humidification is performed inside the clean room. According to such an ozone fumigation circuit, ozone is directly added by the second ozone generator 7 to air having a low concentration of ozone to which ozone has been added by the first ozone generator 6□, and this high concentration of ozone is supplied to the clean room 1 by lines R6 and R7,
Ozone fumigation of clean room 1 is performed. Air discharged from the clean room 1 is circulated to the air cleaner 6 through a line R9, forming a closed circuit. in this case,
The line through Hepafilter-2 is not used. The clean room 1 is connected to an ozone discharge line R8 that detoxifies and discharges high-concentration ozone from the ozone fumigator to the atmosphere. , the blower in line R3 is operated to release high concentration ozone in the clean room 1 to the atmosphere. On the other hand, operate the blower on line R5 to lower the ozone concentration in the clean room to a predetermined concentration, and then
Activate the clean room operating circuit. Ozone fumigation has a desired D value for spore bacteria (D value generally means that the number of viable bacteria is reduced to one-tenth (90% killed).
It is defined as the heating time required for the number of viable bacteria to survive, but here it is used as the survival probability of the number of viable bacteria (ID is 1/10, 2D is 1/100, etc.). In this example, the sterilization conditions (ID) are such that the number of surviving spore bacteria is reduced to one-tenth.
The required sterilization time for various ozone concentrations was measured. As a result, the relationship shown in FIG. 3 was obtained. After that, the ozone concentration was 0. A clean room operation was performed to supply air with O2 ppm or more. At that time, airborne bacteria collected outside the clean room were cultured at 30°C for 72 hours, and then put into the operating clean room.
When we investigated the change in the number of viable bacteria over time, we found that the number of viable bacteria had halved after a few hours. From this, it was sufficiently effective in suppressing the growth of bacteria brought in during operation, and it was possible to reliably maintain a sterile state during ozone fumigation. Ozone fumigation usually has an ozone concentration of 20 to 200 ppm.
The sterilization time is 1 to 10 hours, while the clean room operation is performed at an ozone concentration of 0.000000000000 0.000000000 0.0000000000000000000,000 It is carried out at about 5 ppm of O. In this example, ozone fumigation was performed under ID sterilization conditions, but the ozone concentration and sterilization time are not limited to this, and the ozone concentration and sterilization time can be arbitrarily selected within the diagonally shaded area above the ID value series (Figure 3). Is possible. With this clean room cleaning system, the following excellent effects can be expected. (1) By performing ozone fumigation at night, air circulation to the Hepa filter can be stopped even during the idle period, and running costs can be reduced. (2) Ozone fumigation can sterilize surfaces in contact with objects in a clean room. In addition, during ozone fumigation, highly concentrated ozone is supplied from the side wall and exhausted to the side, so it can be diffused to every corner of the clean room, ensuring a uniform concentration and sufficient sterilizing effect even on ozone-resistant bacterial spores. It can completely sterilize non-spore-forming bacteria. (3) Even after discontinuing operation for a long period of time, it is possible to quickly return to a sterile state. In a clean room equipped only with a Hepa filter, there is no way to sterilize the walls, ceiling, machinery, and transport equipment connected to the clean room, so it is possible to return to a sterile state and operate after a long period of suspension. However, according to this system, it is possible to return to a sterile state simply by performing ozone fumigation at night. I can do it. (4) During low-concentration ozone operation, ozone air is supplied into the clean room through the Hepa filter, so microorganisms collected on the inlet side of the Hepa filter can be sterilized. Even if it gets into the clean room, it is safe because it is dead. (5) Furthermore, during low-concentration ozone operation, microorganisms that adhere to the surfaces of walls, ceilings, machines, and transport equipment connected to clean rooms, and bacteria that enter when an operator enters the room, etc. The growth of can be suppressed. (6) Since the inside of the clean room can be kept at room temperature, optimal conditions can be provided for various types of work. In particular, in the case of aseptic filling of food and beverages, containers made of materials other than metal can be used, and the contents to be filled can also be made of substances that may be altered by heating. As described above, the clean room cleaning system of the present invention has excellent effects and can be applied to various uses. For example, it is possible to aseptically fill canned foods, beverages, and other sterilizing substances, as well as manufacture pharmaceutical products. Next, an application example of the present invention will be shown. Of course, it goes without saying that the present invention is not limited to this application example. 1 [Flame] This example is an example in which the present invention is applied to aseptic filling of canned goods, and FIG. 2 schematically shows the clean room cleaning system. In the figure, 1 is a clean room, and its cleaning system is the same as the cleaning system shown in Figure 1, which includes an ozone lid circuit and a clean room operation circuit.
Since each circuit configuration is the same, the description of components other than the HEPA filter 2 is omitted. This clean room 1 is further connected to a line Ra for sterilizing and supplying contents, a line Rb for sterilizing and supplying empty cans, a line Re for sterilizing and supplying can lids, and a line Rd for photographing filled cans. A filler (not shown) for filling empty cans with contents and a seamer (not shown) for sealing the can lid by wrapping it after filling are arranged in the clean room 1. The contents are sterilized by high-temperature short-time sterilization depending on their type, and then supplied to the clean room 1 at room temperature through line Ra using a pump or the like. Empty cans, can lids, etc. are sterilized by an appropriate method such as superheated steam sterilization or chemical sterilization, and then transferred to lines Rb and R, respectively.
e into the clean room 1 at room temperature. Of course, the surfaces of the walls, ceiling, machines, conveyance equipment connected thereto, etc. in the clean room 1 are cleaned and sterilized in advance using appropriate methods such as chemicals and sterile water, as necessary. Preliminary sterilization is especially effective for areas that are not easily exposed to ozone-containing air. In order to make this pre-sterilization treatment effective, in this example,
By using stainless steel panels (not shown) to divide the inside of the clean room 1 into a filler region F, a seamer region S, and other spatial regions, and providing Hepa filters 2 with different effective areas in each region. , the filler region F and the seama region S were each maintained at 10 classes, and the other spatial regions were maintained at 10,000 classes. The degree of vacuum inside the filled can can be adjusted by adjusting the seamer seaming region in the filler region F to an appropriate seaming atmosphere condition using steam and N2. In the system with the above configuration, first, the walls, ceiling, mechanical equipment, etc. in the clean room are cleaned (detergent) → washed with water (sterile water) → fumigated (ozone) → sterilized (chemicals) → washed with water (
A pattern of sterile water) was carried out at night to bring the inside of the clean room to a sterile state for operation. At that time, use 20pp of ozone fumigation as long-term fumigation.
a+X 10 hours, 200 ppm as short-term fumigation
Testing was carried out under various conditions within the range of ×1 hour. Next, a normal operation was performed in which air with an ozone concentration Q and O 5 ppm was supplied, and canned goods were aseptically filled. At that time, the contents to be filled were sterilized at high temperature for a short time, then cooled to room temperature and supplied to the filler. Empty cans and can lids were sterilized in advance with superheated steam, cooled to room temperature, and placed on a delivery line into the clean room. When the obtained canned food was subjected to a bacterial test and a flavor and color test, no problems were found. According to the clean room cleaning system applied to the aseptic filling of canned goods, in addition to the effects of Example 1, the following excellent effects can be expected. (1) The inside of the clean room can be kept at room temperature, and empty cans and can lids can be supplied to the clean room at room temperature along with the sterilized contents. It is not affected by heat from the lid. Therefore, since it is possible to prevent the flavor of the contents from deteriorating, it is possible to fill even contents whose flavor may deteriorate due to heat. Containers made of materials other than metal can also be used. (2) Even in a filling room where the floor is wet and microorganisms that enter through workers' shoes are likely to grow, a sterile state can be maintained due to the growth-inhibiting effect of ozone. (3) When dividing the clean room space into working areas and non-working areas with different classes of sterility, the cleanliness level can be easily changed by changing the effective area of the HEPA filter provided for each divided area. . (Effects of the Invention) As detailed above, according to the present invention, ozone fumigation is performed by supplying highly concentrated ozone into the clean room.
Complete sterilization is possible, and the system can quickly return to a sterile state after a long period of suspension of operation.Furthermore, low-concentration ozone can be supplied into the clean room to maintain a sterile state during operation. , the complete sterilizing effect and the suppressing effect on microbial growth are also remarkable. Furthermore, the clean room can be operated at room temperature. Therefore, this system can be easily applied to various applications and is low cost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of the flow of the clean room cleaning system of the present invention; Fig. 2 is an explanatory diagram schematically showing a configuration example when the present invention is applied to aseptic filling of canned goods; Fig. 3; is a diagram showing the relationship between ozone concentration and sterilization time under sterilization condition ID. 1...Clean room (sterile room), 2...Hepa filter-13...Filter unit, 4...Air handling unit, 5...Heater, 6...Air purifier, 6□... 1st ozone generator, 7... 2nd ozone generator, 8... humidifier, F... filler, S...
...Seema. Patent applicant: Daiwa Seikan Co., Ltd.

Claims (6)

[Claims] (1) It has an ozone fumigation circuit that supplies high-concentration ozone into the clean room, and a clean room operation circuit that supplies low-concentration ozone into the clean room through a filter installed at the clean room entrance. A clean room cleaning system characterized by supplying high concentration ozone to perform ozone fumigation and then supplying low concentration ozone into the clean room to maintain the inside of the clean room in a sterile state. (2) The clean room cleaning system according to claim 1, wherein the high concentration ozone is supplied directly into the clean room without passing through the filter. (3) Claim 1, wherein the filter is a HEPA filter.
The clean room purification system described in . (4) Ozone fumigation at an ozone concentration of 20 to 200 ppm,
Claim 1, 2 or 3: The sterilization time is 1 to 10 hours, and the clean room operation is performed at an ozone concentration of about 0.05 ppm.
The clean room purification system described in . (5) The clean room cleaning system according to claim 1, wherein the clean room is a room for aseptic filling of canned goods. (6) The clean room cleaning system according to claim 5, wherein the filler area, the seamer area, and other spaces are maintained in different cleanliness classes by changing the effective area of the filter. .