KR20120004989A - Sterilisation and/or decontamination of an enclosed environment - Google Patents

Abstract

The sterilization, sanitation and / or purification method may comprise the steps of creating a humidifying environment having a relative humidity higher than ambient humidity; Releasing ozone into the humidifying environment; Maintaining the level of ozone at a concentration that will achieve the required degree of purification and sterilization of the humidifying environment; Reducing the relative humidity of the purified and sterilized environment; And passing the environment through a catalyst to reduce the ozone concentration to a predetermined level.

Description

Sterilization and / or decontamination of an enclosed environment

The present invention relates to methods of sterilization and / or purification, including hygiene, and apparatus for use in such methods.

Within an acceptable time, it is necessary to disinfect and cleanse the enclosed space to destroy potentially harmful microorganisms such as bacteria and viruses that contaminate the air and surfaces in enclosed spaces such as kitchen areas and hospital rooms.

The biocidal activity of ozone is widely known and recognized, and it is also known that the supply of ozone in wet atmosphere increases the biocidal effect.

However, the problems associated with the use of ozone as a biocide include relatively long post-treatment processes to ensure that the environment is safe for the return of the user, the use of potentially harmful chemicals during the process, and the hygiene management of the environment. The overall invalidity of the method, and the overall absence of simplicity of the rapid installation and use of the device.

Applicant's previous application (EP 1500404, Steritrox Limited) described how the beneficial effects of ozone in a humid atmosphere are utilized and the residual atmosphere is free from harmful ozone within a useful time. The method involved adding an olefin compound such as butene-2 to the atmosphere in an amount sufficient to react with and remove all residual ozone. This method is efficient to provide a substantially sterile environment, but the reaction between residual ozone and olefin compounds results in the production of various compounds, some of which are above a certain concentration, commonly referred to as Occupational Exposure Level (OEL) in the atmosphere. If present, it is recognized as having harmful properties. Without prejudice to the invention, the various compounds may include, for example, acetaldehyde, acetic acid, formaldehyde, formic acid, methanol, propionaldehyde, and the like. In addition, the large amount of water that must be provided to achieve the required humidity has some disadvantages.

The present invention seeks to provide a solution to these problems and, in particular, to provide a high degree of sterilization and / or purification method and apparatus which allows a substantially sterilized area to be safe from harmful products within an acceptable time.

According to a first aspect of the invention, as a method of sterilization, purification and / or hygiene, the method comprises:

a) creating a humidifying environment having a relative humidity higher than ambient humidity;

b) releasing ozone into the humidifying environment;

c) maintaining the level of ozone at a concentration that will achieve the required degree of purification, sterilization and / or sanitation of the humidifying environment;

d) reducing the relative humidity of the purification, sterilization and / or sanitary environment; And

e) after reducing the relative humidity of the environment, passing the purge, sterilization and / or sanitary environment through a catalyst to reduce the concentration of ozone to a predetermined level.

The water obtained during step d) can be selectively collected and reused in the method of creating a humidifying environment, thereby reducing the amount of water used by the method and eliminating the need for treatment of waste water.

Reduction of relative humidity may be achieved by one or more of a dehumidification step, passage through an absorbent in the environment to remove water molecules, and / or heating of the environment. Preferably, the method includes all of these steps to reduce relative humidity.

Preferably, hydrocarbons comprising carbon-carbon double bonds are then introduced into the environment to preferentially react with residual ozone. Preferably, the hydrocarbon comprises a cis or trans secondary olefin, including cyclic olefins. The clarified and sterilized environment can be recycled through the catalyst until the concentration of the harmful product drops to a safe level.

The humidification environment is preferably about 90% v / v at ambient temperature and lowered to the lowest level of about 30% before passing through the catalyst. Preferably, the humidifying environment has a partial pressure of water vapor of at least 5.00 torr, but this will depend on the temperature of the environment. For example, a cool environment with a temperature of about 6 ° C. will preferably have a partial pressure of 6.00 Torr, and a warmer environment with a temperature of about 18 ° C. will preferably have a partial pressure of about 13.9 Torr. .

Preferred and / or optional features of the first aspect of the invention are described in claims 2 to 11.

According to a second aspect of the invention there is provided a sterilization, purification and / or sanitary device for use in the method according to the first aspect of the invention, the device comprising a humidifier unit, an ozone releasing unit, a humidity reducing means. means, an ozone depletion catalyst and a controller capable of controlling the humidifier unit, the humidity reducing means and / or the ozone emitting unit based on a predetermined condition.

Optionally, the humidity reducing means may comprise recycling means for allowing the collected water to be reused in the humidifier unit.

Preferred and / or optional features of the second aspect of the invention are described in claims 12-20.

The invention is explained more specifically by way of example only with reference to the accompanying drawings in which:

1 is a schematic side elevational view of one embodiment of a sterilization and purification apparatus for carrying out the method of the present invention; And

2 is a schematic front view of the apparatus shown in FIG. 1;

The methods and apparatus of the present invention use ozone at high humidity levels (generally higher than 90% at ambient temperature) for sterilization and purification of one embodiment. However, the actual relative humidity will depend on the temperature of the environment to be treated. The method and apparatus also includes an ozone depletion catalyst to reduce the levels of unwanted by-products such as ozone and hydrogen peroxide to safe levels within a minimum amount of time. This can reduce the time you need to maintain. However, it is rare for the catalyst to operate near the dew point, especially if water is not one of the reactants. This may result in the surface of the catalyst being covered with a film of water molecules, thereby inhibiting the required reaction. In addition, high humidity levels can leave a very moist feeling in the environment after completion of the sterilization / purification method. The present invention alleviates this problem by pretreating the atmosphere before introducing it into the catalytic converter for ozone removal to lower the relative humidity, preferably below 30%.

In one embodiment of the invention, the relative humidity of the environment is reduced by heating the air before introducing it into the catalyst vessel. This shifts the reaction conditions significantly from the dew point, reducing the film thickness of the absorbed water.

In an alternative embodiment of the invention, a dehumidifier is provided before the catalyst. This device has an additional advantage in that the condensed water extracted by the dehumidifier comprises some of the organic byproducts of the reaction, such as acetaldehyde, formaldehyde, acetic acid and formic acid. Residual hydrogen peroxide is also partially removed by such means.

In another embodiment of the present invention, water is removed by, for example, an absorption trap containing molecular sieves or silica gel.

The accompanying drawings illustrate a preferred embodiment of the invention comprising a number of means for lowering the humidity of the atmosphere, namely a dehumidifier unit, an absorption trap in the form of a molecular sieve and a heater. This particular combination has been found to be particularly useful for reducing the level of catalyst deactivation by lowering the level of water present in the atmosphere to an acceptable level. The large amount of water required for this method means that the absorption traps, such as molecular sieves, will soon saturate, requiring frequent replacement or regeneration of the molecular sieves. In contrast, the provision of a dehumidifier removes most of the bulk water from the atmosphere, and the absorption trap further reduces the water level to very low values, thereby extending the potential life of the catalyst before the regeneration step. Before introducing air into the catalyst, heating not only regenerates the trap, but also increases the rate of decomposition of ozone in the catalyst.

An example of a sterilization and purification device 10 for carrying out the method of the present invention may be open and, in use, to create a positive pressure therein to protect sensitive equipment contained in a closed system from the harmful effects of ozone. And a portable enclosure 12. However, it is understood that alternative means may be provided to protect internal sensitive components from destruction by ozone. The hermetic system 12 has a wheel 14, a humidifier unit 16 having a humidified air outlet 17, an ozone discharge unit 18 having an ozone discharge outlet 20, a dehumidifier 90, a moisture absorption unit ( 92, a heater 94, a container containing the ozone catalyst 70, an ozone catalyst fan 71, a hydrocarbon discharge unit 22 having a hydrocarbon discharge outlet 24, and a control unit 26.

The humidifier unit 16 of the illustrated example includes a humidifier 28, a humidity control sensor 30, a temperature sensor 31, and a water reservoir 34. If an ultrasonic humidifier is used, a compressed air supply must be provided, for example in the form of a compressed air tank 32 or container housed in the hermetic system 12. The compressed air tank is connected to the reservoir 34 and the humidifier 28. In order to increase the rate of evaporation to the atmosphere, water droplets having a diameter of less than 5 microns, preferably 2 to 3 microns, are introduced into the air.

The ozone release unit 18 includes an ozone generator 36, an ozone detection sensor 38, and an oxygen supply 56 for supplying oxygen to the ozone generator 36. Oxygen is preferred over air for the production of ozone because oxygen avoids the formation of toxic oxides of nitrogen, increases the rate at which the required ozone concentration is reached, and also increases the yield of ozone.

The dehumidifier unit 90, the moisture absorption device 92, and the heater 94 together form a humidity reducing means.

Ozone catalyst 70 is a suitable catalyst capable of removing ozone from the atmosphere. The catalyst may be selected from a series of proprietary materials known to have activity in the catalytic decomposition of ozone. Such catalysts may optionally include platinum group metals, manganese oxides, and other materials that may have a promoting effect.

The hydrocarbon discharge unit 22 comprises a hydrocarbon feed 42 in the form of a tank or vessel containing volatile unsaturated hydrocarbons such as butenes. Preferably, the butene is butene-2. However, hydrocarbons may be suitable hydrocarbons with carbon-carbon double bonds, for reasons that will be apparent below. The choice of hydrocarbon is based on the rate of reaction with ozone and the toxicity of its decomposition products.

The control unit 26 controls the apparatus 10 and is preset with one or more sterilization and purification routines. The control unit 26 comprises a controller 46 and a user interface 48 which is a means by which a user can enter commands into the device 10.

The device 10 may comprise an on-board battery 50 and / or may be connected to a mains power supply. In the case of the onboard battery 50, the battery is preferably rechargeable. If a mains-operated apparatus is provided, it may have a battery back-up system to failsafe the apparatus in case of a power outage of the main power supply.

The device 10 may also include other safety features, such as a safety sensor and a software routine that prevents start-up or initiates shutdown in the event of a system failure.

In use, the device 10 is first placed in an area to be sterilized and clarified. The device 10 is powered on and the control unit 26 performs a primary safety check. If the safety check does not pass, the device 10 is not activated and outputs an appropriate indication using the warning light 52. During this process, safety checks are carried out continuously and in the event of a system failure, the system defaults to the safe mode.

The temperature of the humidified air is higher than the dew point of the environment and therefore no condensation takes place.

The controller 46 continuously monitors the ozone level, the relative humidity via the humidity control sensor 30 and the ambient temperature via the thermocouple 31. After a predetermined time interval, for example, after 10 minutes, if the calculated relative humidity level and / or the required ozone level has not been reached, the controller 46 stops the sterilization and purification routines and provides an appropriate indication.

Oxygen is supplied to the ozone generator 36 and ozone is produced. The generated ozone is then fed to a discharging humidified airstream. The controller 46 provides a suitable indication that the ozone generator 36 is in operation, and monitors the ambient ozone level through the ozone detection sensor 38.

The ozone and water vapor concentrations detected can vary. However, typical settings are 25 ppm v / v ozone and 13.6 Torr. If a preset ozone and water vapor level is detected within the allotted interval, the controller 46 enters a time, known as a "dwell time".

The residence time may also vary, for example, to one hour, and will depend on the degree and / or type of purification / sterilization to be provided. For example, contamination by spores or fungi, such as Clostridium difficile , is generally a bacterium such as listeria and methicillin resistant staphylococcus aureus (MRSA). It requires a longer residence time than contamination by.

During the residence time, ozone concentration and relative humidity are continuously monitored. When the ozone level falls below a predetermined threshold, the ozone release unit 18 is reactivated to replenish the ozone level. If the relative humidity level drops below the calculated value, the humidifier unit 16 is reactivated to recover the water vapor level.

Again, during the reactivator, if the ozone concentration or relative humidity does not reach the predetermined minimum level described above within a predetermined time interval, e.g., 10 minutes, the controller 46 stops the sterilization and purification routine and displays the appropriate indication. Output

After the elapse of the residence time, the controller 46 closes the compressed air valve 54 and the oxygen supply valve 56, and the humidifier unit 16 and the ozone discharge unit 18 are switched off. Thereafter, the pump 71 blows air through the dehumidifier unit 90, the water removal unit 92, and the heater 94. This removes a significant amount of water from the atmosphere, after which the atmosphere is passed through the catalyst 70 to reduce the level of ozone and the level of ozone is continuously monitored. When the concentration of ozone drops to the required level, for example about 8 ppm v / v, the olefin is introduced by the hydrocarbon release valve 58 of the hydrocarbon release unit 22. Continuously monitor the concentration of ozone and lower it to undetectable levels. The catalyst 70 may continue to be used until the concentration of ozone is lowered below the OEL.

If the ozone detection sensor 38 detects that the ozone concentration level is below a predetermined value, for example, 0.2 ppm or less, the controller 46 closes the hydrocarbon discharge valve 58 and indicates that the sterilization and purification routine has been completed. Outputs Depending on the size of the area to be sterilized and clarified, an ozone level of 0.2 ppm is typically achieved within 3 to 4 minutes. The apparatus may include a feedback ozone measurement system (not shown) to determine the amount of hydrocarbons added to the environment, to mitigate the overload of hydrocarbons and associated potential toxicology issues.

If the ozone detection sensor 38 does not indicate that the predetermined safety level of ozone has been reached within a predetermined time interval, for example, 10 minutes, the controller 46 indicates an alert to warn of potentially dangerous ozone levels in the room. Outputs The controller can be programmed so that the time interval before the announcement that the room can be reused is much longer than the standard half life of ozone.

The sterilization and purification apparatus may be integrally formed as part of the region or may be partially portable. For example, the compressed air supply and / or the oxygen supply may be constitutively formed as part of the area to be sterilized and cleaned regularly. Alternatively, the components may be housed in the hermetic system of the device. In this case, the required supply can be connected to the device via a removable umbilical pipe. The apparatus also consists of a main unit and a remotely connected remote controller, each preset routine being remotely initiated by a user outside of the area to be sterilized and / or cleaned.

The oxygen supply is typically in the form of one or more oxygen tanks or cylinders, but a commercially available oxygen concentrator can be used.

The apparatus utilizes a fan 72 as a gas movement device for circulating humidified air, ozone and hydrocarbons. However, depending on the particular application, an air mover may be used instead of an electric fan.

The apparatus described above utilizes a method of generating artificially high levels of non-condensing humidity and generating high concentrations of ozone in situ.

The material of the device is resistant to the corrosive effects of ozone and the solvent effects of hydrocarbons.

The state of all valves is monitored using an integrally incorporated sensor connected to the controller. The valve is failsafe to a suitable position, such as a closed position, so that user safety is always maintained. The controller may also incorporate a tamper proof recording system to monitor usage, time, date, driving success / failure, and other parameters required to measure the performance of the device.

In another embodiment of the present invention (not shown), the water collected from the dehumidifier can be directed into the original water container, water reservoir, or separate container for reuse in subsequent processing. This has the additional advantage of reducing the amount of water used in the process and the need for wastewater treatment.

Thus, it is possible to provide a method and apparatus for providing sterilization and / or purification which is fast and effective and does not require frequent replacement of the ozone catalyst. In addition, the device may be individual and portable. The method can provide at least 99.99% effective sterilization and purification without harmful environmental by-products. Thus, rapid re-use of contaminated areas is realized.

The foregoing embodiments are provided by way of example only and other variations will be apparent to those skilled in the art without departing from the scope of the invention as defined by the appended claims.

Sterilization and Purification System (10) Portable Enclosure (12)
Humidifier Units with Wheels (14)
Humidification Air Outlet (17) Ozone Release Unit (18)
Ozone Release Outlet (20) Hydrocarbon Release Unit (22)
Hydrocarbon Emission Outlet (24) Control Unit (26)
Humidifier (28) Humidity Control Sensor (30)
Temperature Sensors (31) Compressed Air Tanks (32)
Water reservoir (34) Ozone detection sensor (38)
Ozone Generator (36) Hydrocarbon Supply (42)
Controller 46 User Interface 48
On-board battery (50)
Warning Light (52) Compressed Air Valve (54)
Oxygen Supply / Oxygen Supply Valve (56) Hydrocarbon Release Valve (58)
Ozone Catalyst (70) Ozone Catalyst Fan (Pump) (71)
Dehumidifier 90, moisture absorption unit 92
Burner (94)

Claims (20)

As a method of sterilization, hygiene and / or purification of an enclosed environment, the method comprises:
a) creating a humidifying environment having a relative humidity higher than ambient humidity;
b) releasing ozone into the humidifying environment;
c) maintaining the level of ozone at a concentration that will achieve the required degree of purification, sterilization and / or sanitation of the humidifying environment;
d) reducing the relative humidity of the purification, sterilization and / or sanitary environment; And
e) passing the purge, sterilization and / or sanitary environment through a catalyst after the reduction of the relative humidity of the environment to reduce the ozone concentration to a predetermined level. The method of claim 1, further comprising introducing a hydrocarbon having a secondary olefin carbon-carbon double bond into the environment and preferentially reacting with the ozone released. The method of claim 2, further comprising recycling the purge, sanitary, and / or sterilizing environment through the catalyst until the concentrations of ozone and hydrogen peroxide are reduced to safe levels. 4. The process according to claim 1, 2 or 3, further comprising the step of recycling the water obtained in step d) and recycling the water in step a). 5. The method of claim 1, wherein the reduction in relative humidity is achieved by a dehumidification step. 6. The method of claim 1, wherein the reduction in relative humidity is achieved by passing the environment through a water absorbent to remove water molecules. The method of claim 1, wherein the reduction in relative humidity is achieved by heating the environment. 5. The method of claim 1, wherein the reduction in relative humidity is achieved by a dehumidifying step followed by passage through an absorbent in the environment and heating of the environment. The process according to any one of claims 1 to 8, wherein the level of ozone maintained in step c) is in the range of 1 to 100 ppm v / v. The method of claim 1, wherein step d) reduces the level of ozone to below an occupational exposure level (OEL). The method of claim 1, wherein the relative humidity is reduced by about 30% based on ambient conditions. A sterilization and purification apparatus for use in the method as claimed in claim 1, wherein the apparatus comprises a humidifier unit, an ozone release unit, a humidity reducing means, an ozone depleting catalyst, and the humidifier unit, ozone release And a controller capable of controlling the unit and / or the humidity reducing means based on pre-determined conditions. 13. The apparatus of claim 12, further comprising recycling means for recycling the water obtained by said humidity reducing means. The device according to claim 12 or 13, wherein the humidity reducing means further comprises a dehumidifier unit. The device according to claim 12 or 13, wherein the humidity reducing means further comprises a moisture absorption unit. The apparatus of claim 15, wherein the absorption unit comprises silica gel. The device of claim 15, wherein the absorption unit comprises a molecular sieve. The device according to claim 12 or 13, wherein the humidity reducing means comprises a heater. The device according to claim 12 or 13, wherein the humidity reducing means comprises a dehumidifier unit, an absorption unit and a heater. The device of claim 12, further comprising a sensor to monitor the relative humidity and concentration of ozone before and after passage through the catalyst.

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