WO2016180855A1

WO2016180855A1 - Vaporizer device for vaporizing a sterilizing agent comprising heated outlet vapour conduit and collector as well as corresponding method of vaporization

Info

Publication number: WO2016180855A1
Application number: PCT/EP2016/060508
Authority: WO
Inventors: Juan Antonio Matachana Aramburu; Jaime MONCLÚS ASCÓN; Josep Oriol ANTONA ELÍAS
Original assignee: Antonio Matachana SA
Current assignee: Antonio Matachana SA
Priority date: 2015-05-12
Filing date: 2016-05-11
Publication date: 2016-11-17
Anticipated expiration: 2017-11-12
Also published as: ES2541503B1; ES2541503A1

Abstract

Vaporizer device for vaporizing a sterilizing agent and the corresponding method of vaporization. The device comprises a chamber (2), at least one sterilizing agent vapor outlet conduit (10), an injector device (12) for injecting the sterilizing agent and first heating means (14) arranged for heating the lower wall (4). The device is characterized in that it further comprises means (24) for reducing pressure inside the chamber (2) and second heating means (26) for the side wall. The injector device (12) is arranged in the upper wall (6), and the sterilizing agent is injected through the injector device (12) from above by means of an injection stream projected on the side wall (8) and lower wall (4) and below the outlet conduit (10). The method according to the invention is based on the same operating principle.

Description

VAPORIZER DEVICE FOR VAPORIZING A STERILIZING AGENT

COMPRISING HEATED OUTLET VAPOUR CONDUIT AND COLLECTOR AS WELL AS CORRESPONDING METHOD OF VAPORIZATION

DESCRIPTION

Field of the invention

The invention is comprised in the field of sterilization, and more particularly in the field of physical or chemical sterilization by means of applying vapor on the product to be sterilized.

More particularly, the invention relates to a vaporizer device for vaporizing a sterilizing agent in liquid state comprising a vaporization chamber delimited by a lower wall, an upper wall and at least one side wall and at least one sterilizing agent vapor outlet conduit, an injector device for injecting said sterilizing agent in liquid state into said chamber, and first heating means arranged for heating said lower wall.

Likewise, the invention relates to a method of vaporization of a sterilizing agent in liquid state comprising the steps of providing a vaporization chamber delimited by a lower wall, an upper wall and at least one side wall, and at least one sterilizing agent vapor outlet conduit, and heating said lower wall.

State of the art

Methods of sterilization based on applying sterilizing agents on an article located in the sterilization chamber of a sterilization installation are widely known in sectors such as medicine or biology. For example, methods of sterilization based on the vapor of agents such as water, hydrogen peroxide or others are very commonly used for sterilizing medical equipment such as endoscopes, surgical or laboratory instruments or the like. In methods of this type it is very important for the sterilizing agent in liquid state to not penetrate the sterilization chamber or to not condense in said chamber, since these products often have a high oxidizing power which may be detrimental to the installation and also the article to be sterilized.

In addition, in methods of sterilization it is very important for the sterilizing agent vapor introduced in the chamber of the sterilizer to be high-quality vapor. In the invention, vapor quality is understood, on one hand, as the correct vaporization of the sterilizing agent, and on the other, the absence of contaminants.

The solution injected in liquid state must be completely vaporized such that when it reaches the sterilization chamber of the sterilizer in vapor state, condensation thereof does not occur.

With respect to the presence of contaminants in the vapor, said presence directly influences sterilizing agent decomposition. Sterilizing agent decomposition negatively and directly affects microbicidal efficacy. This can have extremely dire consequences because then sterilization of the article is poor and the presumably sterilized article becomes a vehicle for spreading pathogenic organisms.

In addition, the materials used are also critical in methods of sterilization. For example, hydrogen peroxide has a high oxidizing action which is highly detrimental as it reacts with most metals. Although hydrogen peroxide is not itself flammable, its decomposition process generates large amounts of heat and oxygen.

With respect to decomposition, hydrogen peroxide naturally decomposes into water and oxygen. Commercially available hydrogen peroxide is very pure and its rate of decomposition into water and oxygen is usually very low. Nevertheless, if hydrogen peroxide is contaminated, for example, with salts from metals such as iron, copper, chromium, vanadium, tungsten, molybdenum, silver and metals from the platinum group, a rapid decomposition can occur, giving rise to oxygen and water. The microbicidal effect is therefore lost since water and oxygen instead of peroxide would be injected into the chamber. Rapid decomposition can also occur with extremely low levels of contaminants, i.e., decomposition can occur with only a few ppm (parts per million) of contaminants. This decomposition is a chain reaction in which the metallic ions are successively oxidized and reduced. It must be taken into account that materials which are "compatible" with hydrogen peroxide can also cause rapid decomposition thereof if their surface is not of suitable quality or has not been suitably prepared.

Another key factor to prevent peroxide decomposition is to prevent the modification of its pH, since the pH has a very significant effect on the rate of decomposition of this sterilizing agent.

Summary of the invention The purpose of the invention is to provide a vaporizer device for vaporizing a sterilizing agent in liquid state of the type indicated above, which allows vaporizing the substance efficiently, providing a high-quality sterilizing agent vapor.

This is achieved by means of a vaporizer device for vaporizing a sterilizing agent of the type indicated above, characterized in that it further comprises means for reducing pressure which, when in operation, are suitable for reducing the pressure inside said chamber to a pressure less than the pressure outside said chamber, and second heating means arranged for heating at least said at least one side wall, and in that said injector device is arranged in said upper wall and configured such that when in operation, said sterilizing agent can be injected through said injector device from above by means of an injection stream projected on said at least one side wall and said lower wall and below said outlet conduit.

In the invention, special reference is made to hydrogen peroxide as a chemical sterilizing agent. Nevertheless, within the scope of the invention the application of the invention in other chemical sterilizers is contemplated, applying a mixture of water vapor and other types of sterilizing agents such as formaldehyde or others.

As a result of the arrangement of the heating means adjacent to the side wall and lower wall simultaneously, a very uniform heat distribution inside the vaporization chamber is obtained. This makes it easier for the agent injected into the chamber to be able to evaporate as soon as it contacts either of both walls on which the agent is injected. In addition, the arrangement of the injector in the upper wall preventing the outlet conduit from getting wet when injecting the stream of sterilizing agent eliminates the risk of condensation outside the vaporization chamber in the outlet conduit, whereas in the interior, vaporization is assured by the immediate contact with one of the hot walls of the chamber. The arrangement also allows using the effect of gravity combined with the use of a larger evaporation surface. Therefore, if those liquid droplets coming into contact with the side walls are not able to evaporate upon contact, they slide downwards, being subjected to the effect of the heat of the wall, which increases the time available for correct evaporation thereof.

The invention further includes a number of preferred features that are object of the dependent claims and the utility of which will be highlighted hereinafter in the detailed description of an embodiment of the invention.

As discussed, another problem associated with methods of chemical sterilization lies in the high oxidation capacity of the sterilizing agents. Therefore, to solve this problem, the lower wall and upper walls and said at least one side wall are preferably made of an aluminum and manganese alloy.

In addition, as discussed another problem associated with chemical sterilization is the vapor quality. To that end, in order to maximize vapor quality said injector device comprises a spray nozzle for spraying said sterilizing agent during injection in the chamber. As a result of the spray nozzle, the size of droplet coming out of the injector is reduced. The smaller the size of the droplet, the easier it is for the sterilizing agent to evaporate when it contacts the walls of the vaporization chamber. The risk of condensation in the sterilization chamber is again reduced.

It is also is important to assure the outflow of the maximum amount of vapor, preventing it from being able to accumulate in unwanted corners of the chamber. To that end, said at least one outlet conduit is provided adjacent to said upper wall and flows into a collector provided below said lower wall. This causes all rising vapor to immediately exit the chamber, and the risk of vapor condensation in the chamber is therefore minimized. In another embodiment, it is envisaged that the first heating means are arranged adjacent to the upper part of said collector for reducing the risk of condensation of the agent at the outlet of the vaporization chamber.

In another preferred embodiment of the device, it is envisaged that said second heating means extend downward to at least one third the height of said collector measured from the upper part thereof, whereby the risk of condensation is again minimized before the vaporized sterilizing agent condenses prior to exiting the device and entering the sterilization chamber. Finally, in another preferred embodiment the injector device is arranged in the center of said upper wall to achieve a more homogeneous vaporization pattern in the entire chamber of the vaporizer.

The invention also relates to a method of vaporization aimed at vaporization efficiency and through which a high-quality sterilizing agent vapor is obtained. This objective is achieved by means of a method of vaporization of a sterilizing agent in liquid state comprising the steps described above and characterized in that it further comprises the steps of heating said side wall, generating in said chamber pressure which is less than the pressure outside said chamber, and injecting said sterilizing agent from said upper wall on said side walls and said lower wall by means of an injection stream projected on said at least one side wall and said lower wall and below said outlet conduit.

Preferably, it has been found that when the method is applied using hydrogen peroxide as the sterilizing agent, with a concentration comprised between 30 and 65% w/w, and the chamber is heated to a temperature comprised between 60 and 120⁵C, optimum results are achieved in the method.

Another relevant problem relates to improving evaporation chamber transients and installation consumption. To that end, preferably, in said step of generating pressure, the pressure generated inside said chamber is less than 5 mbar, which allows reducing the temperature required for peroxide evaporation.

It has also been found that, preferably, when in said step of injecting the sterilizing agent is injected into said chamber at a pressure comprised between 6 and 10 bar, a higher quality vapor is achieved.

In a particularly preferred manner, the sterilizing agent is injected from the center of said upper wall.

In another embodiment, the method comprises the steps of extracting the sterilizing agent through at least one outlet conduit adjacent to the upper wall and flowing into a collector provided below said lower wall and said collector being also heated. Likewise, the invention also includes other features of detail illustrated in the detailed description of an embodiment of the invention and in the accompanying figures. Brief description of the drawings

Further advantages and features of the invention will become apparent from the following description, in which, without any limiting character, preferred embodiments of the invention are disclosed, with reference to the accompanying drawings in which:

Figure 1 shows a schematic longitudinal section of the vaporizer device for vaporizing a sterilizing agent in liquid state, in a standby state.

Figure 2 shows a schematic longitudinal section of the vaporizer device along a plane perpendicular to the plane of representation of Figure 1 , in which the vaporizer device is seen as the sterilizing agent is being injected. Figure 3 shows the same view as that of Figure 2, in which the vaporizer device is seen as the sterilizing agent is being vaporized.

Figure 4 shows a schematic view of a sterilization installation with a vaporizer device for vaporizing a sterilizing agent according to the invention.

Detailed description of embodiments of the invention

The vaporizer device 1 for vaporizing a sterilizing agent in liquid state shown in the drawings is basically formed by a metallic housing 22 which is preferably made of an aluminum and manganese alloy.

The housing 22 delimits the vaporization chamber 2 through a lower wall 4, an upper wall 6 and in this case a single cylindrical side wall 8. Chamber 2 can have any shape, such as for example, cylindrical, parallelepiped or others, so it may have several side walls. The vaporizer device 1 also comprises a sterilizing agent vapor outlet conduit 10, located in the upper part of the chamber 2. Likewise, in the upper wall 6 an injector device 12 which is preferably located in the center of this upper wall 6 is provided. In addition, the device 1 also comprises first heating means 14 which are, however, arranged for heating the lower wall 4, i.e., they are arranged below said wall and above a collector 20 that will be explained in detail below.

The device also has means 24 for reducing pressure. The objective of these means is to reduce the pressure inside the chamber 2 such that it is less than the pressure outside the chamber and preferably close to vacuum. As a result, the working temperature of the device can be significantly reduced. As can be seen in Figure 4, the means 24 for reducing pressure act simultaneously on the sterilization chamber 28 and on the chamber 2 of the vaporizer.

Furthermore, second heating means 26 are provided adjacent to the side wall 8 of the chamber 2 by way of vertically arranged heating resistances, parallel to the main axis of the chamber 2 and diametrically facing one another. One of the objectives of the invention is to also minimize installation startup and shutdown times. To that end, as a result of the first and second heating means 14, 26 being electrical heating resistances, the transients during heating of the installation are reduced. Likewise, this configuration achieves a rather homogenous temperature distribution inside the chamber 2, despite the reduced start-up times. Each of the electrical resistances has its own temperature probe regulating the correct working temperature. In addition, the vaporizer device 1 also has its own temperature probe for controlling the temperature inside the chamber 2. There are also provided two pressure switches which would stop the heat input from the first and second heating means 14, 26 if a safety limit is exceeded through an electrical control circuit.

As described, the injector device 12 is arranged centrally in the upper wall 6. Furthermore, the placement thereof is selected such that, when in operation, the injector device 12 injects the stream of sterilizing agent from above the chamber 2, forming a preferably conical stream. As a result, it is projected as homogenously as possible on the side wall and lower wall 8, 6 which favors quick vaporization of the sterilizing agent.

The method of vaporization according to the invention which is carried out in the vaporizer device 1 described in the preceding paragraphs will be described below, applicable to the case of hydrogen peroxide. Nevertheless, a more general concept of the method according to the invention is not limited only to this chemical sterilizing agent, since the operating principle is valid for other chemical sterilizing agents.

First, in the method according to the invention there is envisaged a step of starting-up in which both the lower wall 4 and the side wall 8 of the chamber 2 are heated through the first and second heating means 14, 26. In a particularly preferred manner, the chamber 2 is heated to a temperature comprised between 60 and 120⁵C.

In a preferred embodiment of the invention, the method can start from hydrogen peroxide with a concentration comprised between 30 and 65% w/w. In the example described below, hydrogen peroxide with a concentration of 59% w/w was used. At this concentration, a temperature of 70⁵C inside the chamber 2 has been determined to be particularly suitable.

Preferably, simultaneous to heating the chamber 2, means 24 for reducing pressure generate inside the chamber 2 a pressure less than the external pressure. In this case also applied to hydrogen peroxide, it has been determined that the working pressures inside the chamber 2 are less than 5 mbar, such as 1 .4 mbar, for example.

When the device 1 is in the steady state mode, the sterilizing agent is injected from the upper wall 6 at a pressure comprised between 6 and 10 bar. By way of non- limiting example, in the case of an amount of 1 .5 ml of hydrogen peroxide for a sterilization chamber having a volume of 145 L, a pressure of 7 bar has been found to be optimum. The injection can be carried out through a pneumatic cylinder introducing in the vaporizer the aforementioned predetermined amount. Any equivalent injector device known in the art can also be used. In a particularly preferred manner, the injector device 12 is also a metering device, such that the risk of poor vaporization is minimized.

Injecting such a small amount of peroxide for a large mass of hot aluminum alloy is one of the features significantly favoring vaporization. It must now be pointed out that the aluminum and manganese housing acts in a very favorable manner in vaporization due to its high specific heat which allows readily giving off heat from the first and second heating means 14, 26 to the sterilizing agent to be vaporized.

As seen in Figure 2, a conical stream wetting the side wall 8 and lower wall 4 is projected with the injector device 12. Nevertheless, as seen the sterilizing agent stream 18 exiting the injector device 12 contacts the side wall 8 at a point which is far enough from the upper wall 6 and located below the outlet conduit 10 to prevent any risk of the sterilizing agent in liquid state coming out. It has also been found that another factor favoring correct vaporization is the dimension of the outlet conduit of the injector device 12. For the mentioned injection amounts, a conduit having a circular cross-section with a diameter comprised between 0.5 and 3 mm, for example, 1 mm, is highly favorable.

Optionally, the injector device 12 can have a spray nozzle for spraying the sterilizing agent 18. This reduces droplet diameter and again increases efficiency of the vaporizer device 1 and the vapor quality obtained.

Figure 3 shows that after the sterilizing agent 18 contacts the lower wall 4 and side wall 8, hydrogen peroxide vaporizes automatically, which significantly increases the pressure inside the chamber 2. For that reason and with the sterilizing agent already in vapor phase, said agent exits through the outlet conduits 10 adjacent to the upper wall. Then, it flows into a collector 20 provided below the lower wall 4 and the first heating means 14 through the downwardly extending discharge conduits 30. At this point, the completely vaporized hydrogen peroxide exits the collector 20 towards the chamber of the sterilizer not shown in the drawings. It can also be seen at this point that due to the fact that the first heating means 14 are adjacent to the upper part of the collector 20 and that the second heating means 26 extend downward to one third the height of said collector 20 measured from the upper part thereof, the risk of condensation before entry into the sterilization chamber 28 is again reduced, since the temperature is kept substantially constant throughout the entire path travelled by the vapor.

The embodiment described up until now represents a non-limiting example, such that the person skilled in the art will understand that beyond the example that has been shown, multiple combinations of the claimed features are possible within the scope of the invention.

Claims

1 . - A vaporizer device (1 ) for vaporizing a sterilizing agent in liquid state comprising [a] a vaporization chamber (2) delimited by a lower wall (4), an upper wall (6) and at least one side wall (8) and at least one sterilizing agent vapor outlet conduit (10),

[b] an injector device (12) for injecting said sterilizing agent in liquid state into said chamber (2), and

[c] first heating means (14) arranged for heating said lower wall (4), characterized in that it further comprises

[d] means (24) for reducing pressure which, when in operation, are suitable for reducing the pressure inside said chamber (2) to a pressure less than the pressure outside said chamber (2), and

[e] second heating means (26) arranged for heating at least said at least one side wall, and in that

[f] said injector device (12) is arranged in said upper wall (6) and configured such that when in operation, said sterilizing agent can be injected through said injector device (12) from above by means of an injection stream projected on said at least one side wall (8) and said lower wall (4) and below said outlet conduit (10).

2. - The device according to claim 1 , characterized in that said lower wall and upper walls (4, 6) and said at least one side wall (8) are made of an aluminum and manganese alloy.

3. - The device according to claim 1 or 2, characterized in that said injector device (12) comprises a spray nozzle (16) for spraying said sterilizing agent during injection into said chamber (2).

4. - The device according to any of claims 1 to 3, characterized in that said at least one outlet conduit (10) is provided adjacent to said upper wall (6) and flows into a collector (20) provided below said lower wall (4).

5. - The device according to claim 4, characterized in that the first heating means (14) are arranged adjacent to the upper part of said collector (20).

6. - The device according to claim 4 or 5, characterized in that said second heating means (26) extend downward to at least one third the height of said collector (20) measured from the upper part thereof.

7. - The device according to any of claims 1 to 6, characterized in that said injector device (12) is arranged in the center of said upper wall (6).

8. - A method of vaporization of a sterilizing agent in liquid state comprising the steps of:

[a] providing a vaporization chamber (2) delimited by a lower wall (4), an upper wall (6) and at least one side wall (8), and at least one sterilizing agent vapor outlet conduit (10), and

[b] heating said lower wall (4),

characterized in that it further comprises the steps of:

[c] heating said side wall (8),

[d] generating in said chamber (2) pressure which is less than the pressure outside said chamber (2), and

[e] injecting said sterilizing agent from said upper wall (6) on said side walls and said lower wall (4) by means of an injection stream projected on said at least one side wall (8) and said lower wall (4) and below said outlet conduit (10).

9. - The method of vaporization of a sterilizing agent in liquid state according to claim 8, characterized in that said sterilizing agent is hydrogen peroxide with a concentration comprised between 30 and 65% w/w, and in that said chamber (2) is heated to a temperature comprised between 60 and 120⁵C.

10. - The method of vaporization of a sterilizing agent in liquid state according to claim 8 or 9, characterized in that in said step of generating pressure, the pressure generated inside said chamber (2) is less than 5 mbar.

1 1 . - The method of vaporization of a sterilizing agent in liquid state according to any of claims 8 to 10, characterized in that in said step of injecting the sterilizing agent is injected into said chamber at a pressure comprised between 6 and 10 bar.

12. - The method of vaporization of a sterilizing agent in liquid state according to any of claims 8 to 1 1 , characterized in that said sterilizing agent is injected from the center of said upper wall (6).

13.- The method of vaporization of a sterilizing agent in liquid state according to any of claims 8 to 12, characterized in that it comprises the steps of extracting said sterilizing agent through at least one outlet conduit (10) adjacent to said upper wall (6) and flowing into a collector (20) provided below said lower wall (4), and in that said collector (20) is also heated.