Hydrogen peroxide gas decontamination device

Abstract

To provide a hydrogen peroxide gas decontamination device capable of gasifying hydrogen peroxide aqueous solution in a state of not performing temperature control (constant output of a heater).SOLUTION: A hydrogen peroxide gas decontamination device 1 includes a container 10 for holding a hydrogen peroxide aqueous solution, an aqueous solution dripping unit 20 for dripping the hydrogen peroxide aqueous solution contained in the container 10, and an evaporation unit 30 for instantaneously evaporating the hydrogen peroxide aqueous solution dripped from the aqueous solution dripping unit 20. The evaporation unit 30 includes a plate-shaped evaporation plate 31 for instantaneously evaporating the dripped hydrogen peroxide aqueous solution and a heater 32 for heating the evaporation plate 31. The evaporation plate 31 has a suppressing portion 34 that suppresses the Leidenfrost phenomenon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen peroxide gas decontamination device using hydrogen peroxide gas. [Background technology]

[0002] For isolators used in the pharmaceutical manufacturing field and safety cabinets used in microbiology experiments and handling viruses, it is important to control airborne particles and microorganisms, bacteria, and viruses. In the pharmaceutical manufacturing field, it is required to maintain a sterile manufacturing environment, and the sterility assurance level (SAL) is 10 -6 Furthermore, in a safety cabinet, the inside of the equipment needs to be decontaminated to prevent workers from becoming infected with harmful bacteria and viruses during equipment maintenance.

[0003] Traditionally, fumigation with formaldehyde gas has been the main decontamination method, but formaldehyde is a carcinogenic substance, and its use has been strictly regulated in recent years. In response to this, decontamination methods using alternative agents such as hydrogen peroxide, peracetic acid, and ozone have been considered as alternatives to formaldehyde decontamination. Among these, hydrogen peroxide gas is easier to handle than other alternative agents, and has been widely used in the pharmaceutical manufacturing industry to decontaminate isolators and safety cabinets.

[0004] An example of a hydrogen peroxide gas decontamination device using hydrogen peroxide gas is known, for example, from Patent Document 1. This hydrogen peroxide gas decontamination device is installed in the space to be decontaminated and is equipped with a container for holding hydrogen peroxide water (hydrogen peroxide aqueous solution), a heater that heats the container to heat the hydrogen peroxide water in the container, and a temperature regulator that controls the heater to heat the hydrogen peroxide water to 70 to 90°C.

[0005] There are two types of hydrogen peroxide gas decontamination equipment: a constant concentration method, which measures hydrogen peroxide gas concentration, temperature, humidity, etc. and controls concentration and humidity, and a quantitative method, which determines the amount of hydrogen peroxide gas to be used and the time, etc., in advance and does not control the concentration during decontamination. Decontamination equipment using the constant concentration method is used when decontaminating isolators, etc., but components such as hydrogen peroxide gas resistance measuring devices are expensive, and the decontamination equipment itself is more expensive than a safety cabinet. Therefore, costs can be reduced by using a quantitative method in which the amount of hydrogen peroxide gas and dehumidifier used are determined according to the volume of the safety cabinet. Furthermore, when hydrogen peroxide solution is evaporated, more than half of it is water, and hydrogen peroxide gas itself has properties similar to water vapor, so condensation occurs due to the combined saturation of water vapor and hydrogen peroxide gas, making dehumidification necessary.General hydrogen peroxide gas decontamination equipment dehumidifies the space to be decontaminated beforehand, and continues to control humidity even after hydrogen peroxide gas is generated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-134771 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, hydrogen peroxide gas is generated by dropping an aqueous solution of hydrogen peroxide onto an aluminum plate heated by a heater, causing it to evaporate instantly. However, if the temperature exceeds the instantaneous evaporation temperature, the evaporated hydrogen peroxide vapor will create a curtain below the droplet, causing the Leidenfrost phenomenon, which makes evaporation very slow. Therefore, it is common to control the temperature to a constant value (using PID control for the heater). However, when temperature control is performed, as mentioned above, there is a problem in that components such as the hydrogen peroxide gas resistant measuring instrument become expensive.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a hydrogen peroxide gas decontamination device that can gasify an aqueous hydrogen peroxide solution without temperature control (with a heater at a constant output). [Means for solving the problem]

[0009] In order to achieve the above object, the hydrogen peroxide gas decontamination apparatus of the present invention is a hydrogen peroxide gas decontamination apparatus that decontaminates a space to be decontaminated with hydrogen peroxide gas, a container for containing an aqueous hydrogen peroxide solution; an aqueous solution dripping unit for dripping the aqueous hydrogen peroxide solution contained in the container; an evaporation section that instantaneously evaporates the aqueous hydrogen peroxide solution dropped from the aqueous solution dropping section, the evaporation unit includes a plate-shaped evaporation plate that instantly evaporates the dropped hydrogen peroxide solution, and a heater that heats the evaporation plate; The evaporation plate is characterized by having a suppression portion that suppresses the Leidenfrost phenomenon.

[0010] The Leidenfrost phenomenon occurs when a film of vapor forms below the droplet and it no longer comes into contact with the evaporation plate. Therefore, this phenomenon can be prevented by increasing the contact area with the droplet to increase heat conduction and evaporating the droplet the moment it comes into contact, or by allowing the vapor to escape and maintaining contact between the droplet and the evaporation plate. Therefore, as a suppression section, for example, fine scratches can be made on the surface of the evaporation plate, which is expected to have the effects of increasing the surface area and contact area, and allowing steam to escape through the gaps in the unevenness of the fine scratches.

[0011] In the present invention, the plate-shaped evaporation plate that instantly evaporates the hydrogen peroxide solution dropped from the solution dropping section has a suppression section that suppresses the Leidenfrost phenomenon, making the Leidenfrost phenomenon less likely to occur. Therefore, even if the evaporation plate temperature is slightly excessive, the hydrogen peroxide solution can still be instantly evaporated, and a deviation of about 10 to 20°C from the appropriate temperature (about 140°C) is within the allowable range. This allows the hydrogen peroxide solution to be gasified without precise temperature control using a temperature controller or the like (with the heater at a constant output).

[0012] In the above-described configuration of the present invention, the suppression portion may be formed by a large number of irregularities having a depth of several μm to several tens of μm formed on the surface of the evaporation plate onto which the aqueous hydrogen peroxide solution is dropped. If the depth of the unevenness is less than a few micrometers, the vapor cannot escape and a vapor film is likely to form below the droplet. On the other hand, if the depth exceeds several tens of micrometers, a partial vapor curtain will form, and part of the droplet will no longer come into contact with the evaporation plate, slowing down evaporation.

[0013] According to this configuration, the suppression portion is made up of a large number of irregularities having a depth of several μm to several tens of μm formed on the surface of the evaporation plate, so that the Leidenfrost phenomenon is more reliably prevented from occurring.

[0014] When hydrogen peroxide solution (35%) is evaporated, more than half of it is water, and hydrogen peroxide gas itself has properties similar to water vapor, so condensation occurs due to the combined saturation of water vapor and hydrogen peroxide gas, making dehumidification necessary.General hydrogen peroxide decontamination equipment dehumidifies the space to be decontaminated beforehand, and continues to control humidity even after hydrogen peroxide gas is generated.

[0015] Therefore, the above-described configuration of the present invention may include a dehumidifying section that dehumidifies the space to be decontaminated. The dehumidifying section uses a system where the desiccant (type B silica gel) is replaced each time, eliminating the need for a separate dehumidifier. Type B silica gel has a low moisture absorption capacity at low humidity and a large adsorption capacity at high humidity, so it is used to prevent condensation.

[0016] After the space to be decontaminated has been decontaminated with hydrogen peroxide gas, the hydrogen peroxide gas must be decomposed until its concentration is less than 1 ppm, which is the allowable concentration.

[0017] Therefore, the above-described configuration of the present invention may include a decomposition unit that decomposes the hydrogen peroxide gas. The decomposition section may be any section that includes, for example, a hydrogen peroxide decomposition catalyst and a fan that blows gas containing hydrogen peroxide gas present in the space to be decontaminated to the hydrogen peroxide decomposition catalyst. [Effects of the Invention]

[0018] According to the present invention, the aqueous hydrogen peroxide solution can be gasified without temperature control (with the heater at a constant output). [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a front view showing a schematic configuration of a hydrogen peroxide gas decontamination apparatus according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. 2 is a cross-sectional view schematically showing the suppression section of the first embodiment. [Figure 4] 1 is a schematic cross-sectional view showing a state in which a hydrogen peroxide gas decontamination apparatus according to an embodiment of the present invention is installed in a safety cabinet. [Figure 5] 1 shows an experimental example of the hydrogen peroxide gas decontamination apparatus according to the present invention, in which (a) is a front view of a safety cabinet showing the placement position of a biological indicator (BI), and (b) is a side view of the same. [Figure 6] 10 is a graph showing the relationship between the hydrogen peroxide concentration, humidity in the BSC, and elapsed time when the temperature is 23° C. and the relative humidity is 40% RH. [Figure 7] 10 is a graph showing the relationship between the hydrogen peroxide concentration, humidity in the BSC, and elapsed time when the temperature is 23° C. and the relative humidity is 70% RH. [Figure 8]10 is a graph showing the relationship between the hydrogen peroxide concentration, humidity in the BSC, and elapsed time when the temperature is 28° C. and the relative humidity is 40% RH. [Figure 9] 10 is a graph showing the relationship between the hydrogen peroxide concentration, humidity in the BSC, and elapsed time when the temperature is 28° C. and the relative humidity is 70% RH. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of a hydrogen peroxide gas decontamination apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the schematic configuration of a hydrogen peroxide gas decontamination apparatus according to this embodiment, and FIG. 2 is a plan view of the same.

[0021] As shown in Figures 1 and 2, hydrogen peroxide gas decontamination apparatus 1 is used to decontaminate a space to be decontaminated, such as the inside of a safety cabinet, using hydrogen peroxide gas, and is equipped with a container 10 for containing aqueous hydrogen peroxide solution S, an aqueous solution dripping unit 20 for dripping the aqueous hydrogen peroxide solution S contained in container 10, and an evaporation unit 30 for instantaneously evaporating the aqueous hydrogen peroxide solution S dripped from aqueous solution dripping unit 20.

[0022] The container 10 is, for example, a transparent beaker, and is placed on a support stand 11. The container 10 contains an aqueous hydrogen peroxide solution S, and the top opening is closed by a lid (not shown). By opening the lid, the aqueous hydrogen peroxide solution S is filled into the container 10. The aqueous solution dripping section 20 comprises a cylindrical resin suction pipe 21 whose tip (lower end) is inserted into the container 10, a pump 22 to which the upper end (base end) of the suction pipe 21 is connected, a supply pipe 23 whose base end is connected to the pump 22, and a dripping pipe 24 connected to the tip of the supply pipe 23.

[0023] Drip pipe 24 is disposed vertically and supported by support frame 25. The tip (lower end) of drip pipe 24 faces downward. In this aqueous solution dripping unit 20, by operating pump 22, the aqueous hydrogen peroxide solution S in container 10 is sucked by suction pipe 21 and then supplied to drip pipe 24 through supply pipe 23, and the aqueous hydrogen peroxide solution S is dripped from the opening at the lower end. The liquid flow rate of the drip tube 24 is, for example, 0.6 ml / min.

[0024] The evaporation section 30 includes a plate-shaped evaporation plate 31 that instantly evaporates the aqueous hydrogen peroxide solution S dropped from the dropping pipe 24 , a heater 32 that heats the evaporation plate 31 , and a heat insulating plate 33 . The evaporation plate 31 is formed from a square aluminum plate, and has, for example, dimensions of 50 mm×50 mm in plan view and a thickness of 10 mm.

[0025] The evaporation plate 31 has a suppression portion 34 that suppresses the Leidenfrost phenomenon. As shown in FIG. 3, this suppression section 34 is made up of a large number of irregularities 34 having a depth d of several μm to several tens of μm, which are formed on the surface of the evaporation plate 31 onto which the aqueous hydrogen peroxide solution S is dropped. The suppression portion (unevenness) 34 is formed by, for example, using a metal brush for removing rust to make fine scratches on the surface of the evaporation plate 31. The size and direction of the fine scratches vary randomly to some extent in size (several μm to several tens of μm in depth), and the scratches overlap vertically, horizontally and diagonally.

[0026] Another method for creating the evaporation plate 31 is to create a grid of grooves about 10 to 50 μm deep, and then make fine scratches of a few μm in size without crushing the grooves, thereby increasing the surface area. This would have a similar effect (even better than the current effect if the size of the irregularities could be adjusted through experiments, etc.), but on the other hand, fine machining would be expensive.

[0027] In such a suppression section 34, the surface of the evaporation plate 31 has small scratches and irregularities, which is expected to have the effects of increasing the surface area and contact area, and allowing steam to escape through the gaps between the small scratches and irregularities. The Leidenfrost phenomenon occurs when a film of vapor forms below the droplet and it no longer comes into contact with the evaporation plate 31. Therefore, the Leidenfrost phenomenon is less likely to occur if the contact area with the droplet is increased to increase heat conduction and cause the droplet to evaporate the moment it comes into contact, or if the vapor is allowed to escape and the droplet and evaporation plate 31 are maintained in contact. Therefore, by making fine scratches on the surface of the evaporation plate 31 as the suppression section 34, it is possible to expect both the effect of increasing the surface area and contact area, and the effect of allowing steam to escape through the gaps in the unevenness of the fine scratches.

[0028] Heater 32 is a plate- or string-shaped electric heater that is installed below evaporation plate 31 and adjusts the heater output to balance so that the surface of evaporation plate 31 is approximately 140°C when the hydrogen peroxide solution is dropped. This adjustment is performed by a control unit (not shown) to which heater 32 is connected. The heater 32 may be embedded in the evaporation plate 31. In this case, it is necessary to make the evaporation plate 31 thicker, for example, 20 mm, and to provide a sufficient distance between the heater 32 and the evaporation surface. In addition to the heater 32, the control unit also controls the pump 22, and fans 42, 53, 61, and 65, which will be described later.

[0029] The heat insulating plate 33 is provided between the lower surface of the heater 32 and the upper surface of the support base 11, and suppresses the conduction of heat generated by the heater 32 to the support base 11. This allows the heater 32 to heat the evaporation plate 31 effectively.

[0030] The hydrogen peroxide gas decontamination apparatus 1 of this embodiment also includes a dehumidifying unit 40 that dehumidifies the space to be decontaminated. Specifically, as shown in FIG. 1, the dehumidifying unit 40 is provided above the support base 11 and includes a filling tube 41 filled with a dehumidifying agent d, and a fan 42 provided between the bottom of the filling tube 41 and the support base 11. Type B silica gel is used as the dehumidifying agent d filled in the filling tube 41, and this dehumidifying agent d is replaced after each decontamination. Type B silica gel has a low moisture absorption capacity at low humidity and a large adsorption capacity at high humidity, and is therefore used to prevent condensation.

[0031] In this dehumidifying unit 40, when the fan 42 is operated, gas (air, etc.) in the space to be decontaminated passes through the dehumidifying agent d in the filling tube 41, is dehumidified, and then flows into the inside of the support base 11 and is exhausted into the space to be decontaminated from the exhaust port 11a provided on the top surface of the support base 11. This reduces the humidity in the space to be decontaminated.

[0032] After the hydrogen peroxide gas decontamination apparatus 1 has decontaminated the space to be decontaminated with hydrogen peroxide gas, the hydrogen peroxide gas needs to be decomposed until its concentration drops to less than 1 ppm, which is the allowable concentration. For this reason, the hydrogen peroxide gas decontamination apparatus 1 of this embodiment is provided with a decomposition section 50 that decomposes hydrogen peroxide gas.

[0033] That is, as shown in FIG. 2, the hydrogen peroxide gas decontamination apparatus 1 includes the decomposition section 50 behind the dehumidification section 40. Decomposition section 50 includes rectangular box-shaped storage section 51, hydrogen peroxide decomposition catalyst 52 provided within storage section 51, and fan 53 provided within storage section 51 for blowing gas containing hydrogen peroxide gas present in the space to be decontaminated to hydrogen peroxide decomposition catalyst 52. Fan 53 is attached to the back surface of the wall portion that faces evaporation section 30, among the wall portions that form storage section 51, and an intake port of fan 53 is exposed from the wall surface through opening 51a formed in said wall surface. In addition, hydrogen peroxide decomposition catalyst 52 is provided in a wall portion that faces the wall portion on which fan 53 is provided, among the wall portions that form storage section 51, and this wall portion is provided with exhaust port 51b that discharges oxygen and water vapor produced by decomposition of hydrogen peroxide gas by hydrogen peroxide decomposition catalyst 52 into the space to be decontaminated.

[0034] In decomposition section 50, after the hydrogen peroxide gas decontamination apparatus 1 has decontaminated the space to be decontaminated with hydrogen peroxide gas, fan 53 is operated, and hydrogen peroxide gas present in the space to be decontaminated is sucked in from the suction port of fan 53 through opening 51a and sent to hydrogen peroxide decomposition catalyst 52. Then, oxygen and water vapor decomposed by hydrogen peroxide decomposition catalyst 52 are discharged into the space to be decontaminated from exhaust port 51b.

[0035] The hydrogen peroxide gas decontamination apparatus 1 of this embodiment is installed in a work room 60a of a safety cabinet 60, as shown in FIG. The safety cabinet 60 is equipped with a fan 61, an air intake filter 62, an exhaust filter 63, etc., and by operating the fan 61, gas in the work chamber 60a is sucked in through the intake ports 60b and 60c, flows through the circulation passage 60d, passes through the air intake filter 62 and is blown out into the work chamber 60a, and also passes through the exhaust filter 63 and is blown out to the outside.

[0036] Since hydrogen peroxide gas is easily adsorbed and does not easily pass through filters 62 and 63 in the absence of airflow, fan 61 is always operated at low speed. In addition, in order to return the gas blown out from exhaust filter 63 to working chamber 60a, a separate duct 64 is installed to circulate the gas from exhaust section 60e into working chamber 60a, and duct 64 is equipped with a circulation fan 65.

[0037] Decontamination of the safety cabinet 60 by the hydrogen peroxide gas decontamination apparatus 1 of this embodiment is carried out through a dehumidification step (DH), a decontamination step (DC), and an aeration step (AR). 1, in the dehumidification step (DH), the fan 42 is operated to cause the gas inside the safety cabinet 60 to pass through the dehumidifying agent d in the filling tube 41, where it is dehumidified, and then flows into the inside of the support base 11 and is exhausted into the space to be decontaminated from the exhaust port 11a provided on the top surface of the support base 11. Such a dehumidification step (DH) is performed to make it easier to increase the hydrogen peroxide concentration in a low-humidity environment and to prevent condensation during initial high humidity conditions.

[0038] Next, in the decontamination process (DC), pump 22 is operated to suck the aqueous hydrogen peroxide solution S from container 10 through suction pipe 21, and then supply it to drip pipe 24 via supply pipe 23, and drip the aqueous hydrogen peroxide solution S from the lower end opening onto the surface of evaporation plate 31. This causes the aqueous hydrogen peroxide solution S to evaporate, increasing the hydrogen peroxide concentration in safety cabinet 60. By providing the surface of the evaporation plate 31 with small scratches and irregularities, in other words, by providing the suppression section 34, the contact area with the droplets is increased, increasing heat conduction and causing the droplets to evaporate the moment they come into contact, or by allowing the vapor to escape and maintaining contact between the droplets and the evaporation plate 31, the Leidenfrost phenomenon is less likely to occur, and the aqueous hydrogen peroxide solution S can be gasified without temperature control (with the heater 32 at a constant output). The gasified hydrogen peroxide (hydrogen peroxide gas) spreads throughout the space to be decontaminated, decontaminating the space.

[0039] 2, after the space to be decontaminated has been decontaminated with hydrogen peroxide gas, fan 53 of decomposition unit 50 is operated, and hydrogen peroxide gas present in the space to be decontaminated is sucked in from the intake port of fan 53 through opening 51a and sent to hydrogen peroxide decomposition catalyst 52. The oxygen and water vapor decomposed by hydrogen peroxide decomposition catalyst 52 are then discharged from exhaust port 51b into the space to be decontaminated, and hydrogen peroxide gas is decomposed until its concentration drops to less than 1 ppm, which is the allowable concentration.

[0040] As described above, according to this embodiment, the evaporation plate 31, which instantaneously evaporates the hydrogen peroxide solution S dropped from the dropping tube 24 of the solution dropping unit 20, has the suppression unit 34 that suppresses the Leidenfrost phenomenon, making the Leidenfrost phenomenon less likely to occur. Therefore, even if the temperature of the evaporation plate 31 is slightly excessive, the hydrogen peroxide solution can be instantaneously evaporated, and therefore a deviation of about 10 to 20°C from the appropriate temperature (about 140°C) is within the allowable range for the evaporation plate temperature. This allows the hydrogen peroxide solution S to be gasified without precise temperature control using a temperature controller or the like (with the heater at a constant output).

[0041] Furthermore, since the suppression portion 34 is made up of a large number of irregularities having a depth of several μm to several tens of μm formed on the surface of the evaporation plate 31, the Leidenfrost phenomenon is more reliably prevented from occurring. Furthermore, since the dehumidifying section 40 for dehumidifying the space to be decontaminated is provided, the humidity in the space to be decontaminated can be reduced as a preparation before the aqueous hydrogen peroxide solution is dripped, and condensation can be prevented when the humidity is initially high. In addition, since the decomposition unit 50 for decomposing hydrogen peroxide gas is provided, the hydrogen peroxide gas can be reliably decomposed until the concentration becomes less than 1 ppm, which is the allowable concentration.

[0042] (Experimental example) Next, an experimental example of decontamination using the hydrogen peroxide gas decontamination apparatus according to the present invention will be described. In the experimental example, decontamination using hydrogen peroxide gas is carried out in three steps: dehumidification step, decontamination step, and aeration step. (1) Dehumidification process (Dehumidification hereinafter called DH process) As a preparation before dripping the hydrogen peroxide solution, the humidity is reduced. This dehumidification process is performed to make it easier to increase the hydrogen peroxide concentration in a low-humidity environment and to prevent condensation during the initial high humidity period. The dehumidifying agent used was 100g of type B silica gel, and the dehumidification process lasted 30 minutes. The hydrogen peroxide solution evaporation section was also preheated during this process.

[0043] (2) Decontamination process (hereinafter called DC process) The hydrogen peroxide solution is evaporated to increase the hydrogen peroxide concentration inside the safety cabinet. The amount of hydrogen peroxide solution used is 0.6 ml / min x 80 min = 48 ml. To prevent condensation, dehumidification is continued during this process.

[0044] (3) Aeration process (hereinafter called AR process) Air is blown over a hydrogen peroxide decomposition catalyst to decompose the hydrogen peroxide. The substance is decomposed until it reaches a concentration of less than 1 ppm, which is the ACGIH (American Conference of Governmental Industrial Hygienists) acceptable concentration for the workplace. It takes about 120 minutes to reach a concentration of around 1 ppm, but the time is set to 180 minutes, taking into account the re-dispersion of substances adsorbed on the inner walls of the safety cabinet and HEPA filters (for example, filters 62 and 63 shown in Figure 4).

[0045] Table 1 shows the times for the dehumidification process (DH process), decontamination process (DC), and aeration process (AR), as well as the control of the dehumidification fan (fan 42 shown in Figure 1), circulatory fan (fan 65 shown in Figure 4), BSC fan (fan 61 shown in Figure 4), H2O2 drip pump (pump 22 shown in Figure 1), evaporation heater (heater 32 shown in Figure 1), catalytic fan (fan 53 shown in Figure 2), etc.

[0046] [Table 1]

[0047] Decontamination verification is carried out as follows: (1) Verification method A biological indicator (MesaLab, HMV-091, G. stearothermophilus (ATCC12980), 1.9 × 106 cfu, hereafter referred to as BI) was used to evaluate decontamination. The BI evaluation was conducted in accordance with Appendix B of JIS K3800 "Biohazard Class II Cabinets" (2021). According to the JIS standard, two BIs are placed in each of the six locations (O1 to O6) shown in Figure 5, and decontamination is deemed successful if at least one of the two BIs is destroyed. After decontamination is complete and the hydrogen peroxide concentration drops to 1 ppm or less, the BIs are collected and cultured at 58°C for seven days to assess the decontamination effect. If decontamination is successful three times in a row, the decontamination method is deemed compliant. This experiment was carried out in a 1300mm wide workbench IIA2 type BSC (safety cabinet). The ambient environment was verified under four conditions: temperature of 23°C and relative humidity of 40%, temperature of 23°C and relative humidity of 70%, temperature of 28°C and relative humidity of 40%, and temperature of 28°C and relative humidity of 70%.

[0048] (2) Verification results The hydrogen peroxide concentration and humidity in the BSC (safety cabinet) during the experiment are shown in Figures 6 to 9, and the results of culturing BI for one week are shown in Table 2. Figure 6 is a graph showing the relationship between hydrogen peroxide concentration, humidity in a BSC (safety cabinet), and elapsed time when the temperature is 23°C and the relative humidity is 40%RH, Figure 7 is a graph showing the relationship between hydrogen peroxide concentration and humidity in a BSC (safety cabinet) when the temperature is 23°C and the relative humidity is 70%RH, Figure 8 is a graph showing the relationship between hydrogen peroxide concentration and humidity in a BSC (safety cabinet) when the temperature is 28°C and the relative humidity is 40%RH, and Figure 9 is a graph showing the relationship between hydrogen peroxide concentration and humidity in a BSC (safety cabinet) when the temperature is 23°C and the relative humidity is 70%RH.

[0049] [Table 2]

[0050] As shown in Figures 6 to 9, the humidity inside the BSC drops to 25-40% RH during the DH process, and then rises to 70-75% RH when the hydrogen peroxide solution is evaporated in the subsequent DC process. The reason why the humidity at the end was about the same despite the difference in humidity at the start of decontamination is thought to be because the type B silica gel used for dehumidification has the property of easily adsorbing moisture at higher humidity levels. During the DC process, the hydrogen peroxide gas concentration on the secondary side of the exhaust filter (shown by curve (2)) rises about 5 minutes after the concentration on the workbench (shown by curve (1)), and peaks about 30 minutes after the start of the DC process. Because hydrogen peroxide gas interacts with water vapor, it reaches high concentrations when the temperature is high and the humidity is low, and the hydrogen peroxide gas concentration decreases as the humidity rises. In addition, because some of the hydrogen peroxide gas is adsorbed onto the filter and walls, the concentration on the secondary side of the exhaust filter is about 60-80% of that on the workbench. After the AR process, the hydrogen peroxide gas concentration was approximately 0.2 to 0.5 ppm.

[0051] (3) Results Under all three conditions where the initial temperature and humidity were changed, at least one of the two BIs placed in one location tested negative, indicating successful decontamination. Therefore, this decontamination method is suitable. The reason why some of the BIs tested positive is presumably because hydrogen peroxide gas is difficult to permeate and penetrates both the filter (HEPA filter) filtration material and the BI nonwoven fabric, and there was insufficient time to perform decontamination. Additionally, the reason why conditions starting with high humidity tend to produce positive results is thought to be that, while humidity is at the same level at the end of the DC process regardless of the humidity at the start of decontamination, hydrogen peroxide gas concentration is more likely to rise when decontamination is started with low humidity. [Explanation of symbols]

[0052] 1 Hydrogen peroxide gas decontamination equipment 10 containers 20 Aqueous solution dripping section 30 Evaporation section 31 Evaporation plate 32 Heater 34 Control Department 40 Dehumidification section 50 Disassembly section

Claims

1. A hydrogen peroxide gas decontamination device that decontaminates a space to be decontaminated with hydrogen peroxide gas, a container for containing an aqueous hydrogen peroxide solution; an aqueous solution dripping unit for dripping the aqueous hydrogen peroxide solution contained in the container; an evaporation section that instantaneously evaporates the aqueous hydrogen peroxide solution dropped from the aqueous solution dropping section, the evaporation unit includes a plate-shaped evaporation plate that instantly evaporates the dropped hydrogen peroxide solution, and a heater that heats the evaporation plate; The hydrogen peroxide gas decontamination device is characterized in that the evaporation plate has a suppression portion that suppresses the Leidenfrost phenomenon.

2. The hydrogen peroxide gas decontamination device according to claim 1, characterized in that the suppression section is composed of a number of irregularities having a depth of several μm to several tens of μm formed on the surface of the evaporation plate onto which the hydrogen peroxide aqueous solution is dripped.

3. 3. The hydrogen peroxide gas decontamination apparatus according to claim 1, further comprising a dehumidifying unit that dehumidifies the space to be decontaminated.

4. 3. The hydrogen peroxide gas decontamination apparatus according to claim 1, further comprising a decomposition unit for decomposing the hydrogen peroxide gas.

5. 4. The hydrogen peroxide gas decontamination apparatus according to claim 3, further comprising a decomposition unit for decomposing the hydrogen peroxide gas.

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