HK1075626B - Hydrogen peroxide vapor system with replaceable desiccant cartridge and the method of using the same - Google Patents

Description

Hydrogen peroxide vapor system with replaceable desiccant cartridge and method of use

Technical Field

The invention relates to a peroxide steam treatment technology, in particular to hydrogen peroxide steam sterilization and disinfection. The invention has particular application to hydrogen peroxide vapor sterilization systems in which the peroxygen vapor is entrained in dry air that has been dried by a desiccant, as will be described with particular reference thereto. It will be appreciated that the present invention can be used with other peroxy vapors in connection with sterilization, sanitation, and other processes.

Background

Previously, a solution of hydrogen peroxide and water was vaporized and entrained in dry air. Steam and air are pumped into a sterilization or other processing chamber. The hydrogen peroxide reacts with microorganisms and other detergents in an oxidation reaction, deactivating them and converting the vapor molecules from peroxide to water. To maintain a predetermined concentration of hydrogen peroxide in the chamber, air and steam in the chamber are circulated to the vaporizer. The hydrogen peroxide vapor in the extracted air is decomposed catalytically or by heating to water vapor. The water vapor is then removed from the air, leaving dry air to be recycled to the vaporizer.

One technique for drying air is to use condensation. However, condensation requires a relatively expensive compressor and refrigeration equipment. Moreover, such condensing devices are generally unable to dry the air to a consistent level of humidity.

By passing air and water vapor through the desiccant, a consistent lower level of humidity can be achieved. While the desiccant dries the air consistently to low humidity, it typically takes longer to regenerate it (regeneration) than to saturate it (saturrate). One way to meet these requirements is by using a drying wheel. Air and water are passed through a first portion of the drying wheel until the portion becomes substantially saturated. The wheel is then marked and a new desiccant portion is diverted into the air and water vapor flow path. The saturated portion of the desiccant undergoes a regeneration process (regeneration) at the next few nominal positions of the wheel. Such regenerative desiccant carrying systems are not only expensive and mechanically complex, but also add significantly to the weight and volume of the portable hydrogen peroxide generation system.

US-A-5,173,258 discloses A system for peroxy vapor generation comprising an air dryer which regenerates between cycles.

The US-A-3,338,032 document relates to A desiccant cartridge which is threadedly received into A flow valve at one end and has A detacher (knock out) adjacent its other end.

US-A-4,828,589 discloses A filter unit having A replaceable cartridge filled with hygroscopic desiccant particulate material. A tubular housing having an internal chamber accessible through an openable and closable port. A drying cylinder is selectively placed into the chamber through the port.

The present invention provides an improved novel desiccant drying system which overcomes the aforementioned problems.

Disclosure of Invention

According to one aspect of the invention, there is provided a peroxy vapor system comprising: a liquid peroxygen solution interface for receiving a source of liquid peroxygen solution; a vapor generation unit for vaporizing the liquid peroxygen solution and entraining the vapor in dry air for delivery to a point of use; and a desiccant dryer coupled to the steam generation unit to dry the air containing steam prior to entraining the steam in the dry air. A pair of nipples (screw joints) interconnect the dryer and the steam generating unit. The dryer further includes a desiccant chamber connected between the end members, each end member including an aperture that receives one of the threaded fittings in liquid-tight relation, and at least one latch for latching the end member to the threaded fitting.

According to another aspect of the invention, a disposable desiccant drying cartridge for such a system is provided. The disposable desiccant cartridge includes a tubular chamber having end fittings at both ends and sized to be received between the end members and to engage a clamping assembly on the end members. A desiccant material is contained within the tubular chamber. The inlet opening is defined in one end appendix of the tubular element and the outlet opening is defined in the opposite end appendix. An annular seal surrounds the bore of the end fitting. A shield member located over each end aperture is used to retain the desiccant material within the tubular member. A removable vapor barrier seal closes the end aperture to prevent moisture from entering the desiccant dryer before the vapor seal is removed.

According to another aspect of the invention, a method of using the above system is provided. A source of liquid peroxygen solution is connected to the mouthpiece of the vaporizer. The liquid peroxygen solution is vaporized and the vapor is entrained in dry air. Steam entrained in the air is supplied to the point of use. Returning air and vapor from the point of use through the replaceable desiccant dryer. The replaceable desiccant dryer is replaced when or before it is saturated.

One advantage of the present invention is that it is simple and low cost.

Another advantage of the present invention is that it ensures sufficient desiccant drying capacity.

A further advantage of the invention is that it ensures a predictably low humidity of the drying air.

Further advantages of the present invention will become apparent to those of ordinary skill in the art from a reading of the following description of the preferred embodiments.

Drawings

The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIG. 1 is a schematic view of a hydrogen peroxide vapor decontamination system according to the present invention;

FIG. 2 is a side view of the peroxy vapor generation system;

FIG. 3 is an end view of the system of FIG. 2;

FIG. 4 is a top view of the vaporizer unit and disposable dryer cartridge embodiment of FIGS. 2 and 3;

FIG. 5 is an enlarged view of the desiccant cartridge of FIGS. 2-4;

FIG. 6 is an enlarged cross-sectional view of the end of the barrel of FIG. 5;

FIG. 7 is a side cross-sectional view of the desiccant cartridge receiving assembly of FIGS. 2-4;

FIG. 8 is a front view of the upper portion of the assembly of FIG. 7;

FIG. 9 is a top view of the assembly of FIG. 7;

FIG. 10 is a side view of the vaporizer system of FIG. 2 with a replaceable, reusable dryer;

FIG. 11 is an end view of the alternative embodiment of FIG. 10;

FIG. 12 is a top view of the vaporizer unit and reusable dryer cartridge embodiment of FIGS. 10 and 11 with the door of the front viewing plate partially opened;

FIG. 13 is a side cross-sectional view of the reusable dryer cartridge of FIGS. 10-12; and

fig. 14 is a schematic diagram of a regenerator unit for the cartridge of fig. 10-13.

Detailed Description

Referring to figures 1, 2, 3 and 4, the steam generation unit 10 vaporizes the peroxygen solution from the solution source 12 and entrains the steam in the dry air that has been dried by the dryer 14. The dry air and steam are delivered to a process chamber, such as isolator 16.

In the preferred embodiment, the source of peroxy solution is a container or cartridge containing aqueous hydrogen peroxide that is received in the cartridge interface 20. After the cartridge is positioned in the cartridge interface portion, it may be interconnected with a dip tube assembly for withdrawing the solution. While the use of steam of aqueous hydrogen peroxide is preferred, other solutions are contemplated, such as solutions of peracetic acid with water, other solutions of peroxides with water, solutions of peroxides with ethanol and water, and the like. In a preferred embodiment, the solution of hydrogen peroxide and water is 35-50% hydrogen peroxide.

The vaporizer system includes an injection pump 22 for injecting a metered amount of peroxygen solution into a vaporizer 24. In a preferred embodiment, the vaporizer is a heated surface, such as a heated plate or the inner surface of an orifice, onto which the peroxygen solution is sprayed or impinged to form a vapor of peroxygen and water. The drying air from the dryer 14 is preheated in a preheater 26 and supplied to the vaporizer to entrain hydrogen peroxide or other peroxy vapor and water vapor. The steam entrained in the air is supplied to the treatment chamber 16.

In the chamber, the hydrogen peroxide vapor reacts with microorganisms and other contaminants in an oxidation reaction to inactivate the microbial material, leaving water vapor suspended in the air. Thus, the hydrogen peroxide concentration in the chamber is gradually reduced over time. To maintain the concentration of hydrogen peroxide vapor, a portion of the vapor and air is withdrawn and passed through a destroyer 28, such as a copper ball. The copper balls catalytically decompose the remaining peroxygen vapour into water vapour and oxygen. The blower 30 is used to provide the motive force for moving the air and steam, which is pumped to the dryer 14. The desiccant in the dryer absorbs the water vapor so that air with an accurately predictable low humidity can be discharged to the preheater 26. In this manner, air of known humidity is supplied to the vaporizer, thereby allowing the vaporizer to optimize the concentration of the peroxy vapor without the need for condensation. It should be noted that if a large amount of undesirable water vapor is returned to the vaporizer, the additional vapor content of the saturated air will push the total content of one or both of the peroxygen and water vapor beyond its condensation point.

In a preferred embodiment, the dryer 14 includes a disposable desiccant cartridge 40 that is clamped into a clamping assembly 42.

Referring to fig. 5 and 6, the desiccant cartridge comprises a cylindrical barrel 44 closed at both ends by end caps 46 to form a cartridge body of a predetermined length. The middle of each end cap has a hole 48 to allow gas to enter and exit the cartridge. The inside of the hole is covered with a disc 50 of shielding material (desiccant) to retain a desiccant 52. A water vapor impermeable end seal 54 is adhered to the exterior of each opening to prevent the desiccant within the cartridge from absorbing water vapor prior to installation on the clamp assembly 42. The cells at each end are surrounded by a resilient gasket 56, such as a closed cell foam made of a material that is non-reactive with hydrogen peroxide or other circulating gas.

Referring again to fig. 2 and 3, and also to fig. 7, 8 and 9, the clamping assembly 42 includes a pair of end members 60, 62 and a pair of connection angles 64 that maintain the end members 60, 62 in a predetermined fixed spaced relationship. The lower end member 62 includes an inlet connection port, i.e., a bore 70, for interconnection with an outlet nipple 72 of the steam generator assembly 10. The latch assembly 74 engages a flange 76 around the outlet nipple to retain the clamping assembly 42 in connection with the steam generator. The inlet port comprises an L-shaped channel terminating in an outlet port 78 located adjacent the inlet of the cartridge. The lower assembly has a smooth sealing surface 80 around the outlet port 78 to hermetically seal with the lower gasket 56. The lower assembly includes an upstanding semi-circular alignment surface 82 which receives and locates the lower end of the cartridge in the middle of the outlet port 78.

The upper element 60 includes an outlet port 90 sized to be received in fluid-tight relation by a threaded fitting 92 of the inlet port to dry the gas in the vaporizer unit 10. The locking assembly 94 locks the upper element to the flange 95 of the nipple assembly. The upper element 60 includes an L-shaped channel terminating in an inlet port 96. The inlet port 96 is surrounded by a piston 98 of larger diameter than the desiccant cartridge gasket 56. The piston defines a smooth polished sealing surface 100 in sealing relation with the desiccant cartridge liner. The piston 98 is retracted away from the vaporizing unit 10 by pulling the handle 102 toward the user. A spring 104 biases the piston into engagement with the gasket of the desiccant cartridge. When the desiccant cartridge is to be inserted, the handle 102 is pushed away from the user, causing the piston to retract. This releases the sealing relationship between the piston and the used desiccant cartridge liner and the cartridge is removed. The adhesive seal 54 of the new desiccant cartridge is removed and the desiccant cartridge is inserted into the latching unit 72 until its rear surface engages the alignment surface 82 of the lower element 62 and the mating alignment surface 106 of the upper element 60. The return of the handle 102 to the angled position allows the spring 104 to bias the sealing surface 100 of the piston 98 into a liquid seal with the upper gasket of the desiccant cartridge. An O-ring 108 between the piston 98 and the upper member 60 serves to prevent the passage of steam between the piston and the upper member.

In a preferred embodiment, the desiccant cartridge is sized for an anticipated hydrogen peroxide consumption. In one embodiment, the dryer is sized to accommodate moisture in one cycle of the largest accessory under worst case conditions. In this embodiment, the desiccant cartridge is replaced at the beginning of each cycle. In another embodiment, the desiccant cartridge is sized to absorb all of the water vapor generated by the contents of the hydrogen peroxide container. In this embodiment, the desiccant cartridge is replaced each time the hydrogen peroxide container is replaced. In another embodiment, the desiccant cartridge is sized to hold water generated by multiple hydrogen peroxide containers. In yet another alternative embodiment, the desiccant cartridge includes an indicator that provides a visual indication that the cartridge is nearly saturated and should be replaced. In yet another alternative embodiment, the vaporization unit 10 includes a moisture sensor that senses the humidity of the air entering the preheater. When the humidity begins to increase, the vaporization unit provides a visual or audio signal indicating that the desiccant cartridge 40 should be replaced.

In another alternative embodiment, the alignment surfaces 82, 106 have protrusions that are received in corresponding recesses on the barrel 40 to ensure proper alignment. In another alternative embodiment, the sealing surface 80 of the lower element 62 and lower end cap have mating projections and recesses outside the periphery of the gasket 56 to ensure alignment. When the handle 102 is pushed to retract the piston, a pawl holds the retracted piston 98. Only when the top of the cartridge is properly received to release the piston will the projection or member on the upper end cap interact with the detent, either directly or through a connector, to release the piston. In another alternative, a cutter may be provided on the lower member 62 and piston 98 to open the end seal 54 when the cartridge is properly aligned.

Referring to fig. 10-13, in another embodiment, the dryer cartridge 40' is directly connected to the threaded fittings 72, 92 of the vaporizing unit 10. This embodiment includes a first or top element 60 ' and a second or lower end element 62 ' interconnected by a desiccant cylinder 44 '. The upper member includes a gasketed bore 90' for receiving an uppermost nipple 92 in fluid-tight relation; and the lower member defines a lower bore (lower well)70 'and a gasket 56' for receiving the lower threaded fitting 72 in a fluid tight manner. The lower latch 74 'engages the latching surface of the lower nipple 72 and the upper latch 94' engages the latching surface of the upper nipple 92. A shield member 50 'is provided adjacent the upper and lower outlets of the cartridge, retaining the desiccant 52' therebetween. A glass sight 110 allows an operator to view a lower desiccant chamber 112 formed between a pair of lower baffles 50'. The color of the desiccant is an indication to the user whether the dryer has been regenerated. In this preferred embodiment, the desiccant quickly becomes clear after the dryer is placed into service. The desiccant will change color (blue in this example) after regeneration.

Preferably, all of the components of the reusable desiccant cartridge are made of metal or other material capable of withstanding repeated exposure to temperatures of about 150 ℃. Alternatively, the cartridge may be a disposable cartridge that is discarded after use.

When the desiccant cartridge is saturated or unable to retain the moisture generated by the next cycle to be performed, the latches 74 ', 94' are released, the desiccant cartridge is removed and replaced with a regeneration cartridge. Referring to fig. 14, the saturated cylinder is placed in the regeneration unit 120. The regeneration unit includes threaded connections of the same size and spacing as the threaded connections 72, 92 of the second embodiment that are inserted into the passages 70 ', 90'. For the cartridge of the embodiment in fig. 5, the manifold 128 includes mating top and bottom connectors. The regeneration unit includes a filter, preferably a HEPA filter 122 capable of removing airborne impurities. Blower 124 blows the filtered air through heater 126 to manifold 128. The manifold is connected to one or more desiccant cartridges 40' to be regenerated. Hot air heated to about 150 c is blown through the desiccant entrained with the absorbed moisture and vented to the atmosphere. The completion of regeneration of the desiccant is determined by measurement of the temperature of the exhaust air using the temperature switch 130 based on time or other factors, after which the circulation of hot air through the desiccant is stopped and the cooling fan 132 is operated. The cooling fan cools the desiccant cartridge to room temperature while the ports of the cartridge remain closed. Once the desiccant cartridge is cooled to a temperature that is safe to handle, the lockable door 134 is released. The desiccant cartridge remains connected to the manifold to prevent cold air from entering the chamber where moisture in the cold air will be absorbed.

Claims (15)

1. A peroxy vapor system comprising: a liquid peroxygen solution interface (20) for receiving a source of liquid peroxygen solution (12); a steam generation unit (10) for vaporizing the liquid peroxygen solution and entraining the steam in dry air for delivery to a point of use; and a replaceable desiccant dryer (14) connected to the steam generating unit for drying the air containing steam prior to entraining the generated steam in the drying air, characterized in that:

a pair of joints (72, 92) for interconnecting the dryer (14) and the steam generating unit (10);

the dryer includes:

a desiccant chamber (44, 44 ') connected between the end elements (60, 62; 60 ', 62 '), each end element including a bore (70, 90; 70 ', 90 ') respectively that receives one of the joints in liquid-tight relation, and

at least one locking member (74, 94; 74 ', 94') for locking the end element to the joint.

2. The system of claim 1, further characterized in that the desiccant dryer (14) includes a desiccant cartridge (40, 40') comprising:

a tubular chamber (44, 44 ') having end fittings (46, 60 ', 62 ') at both ends;

a desiccant material (52') located in the tubular chamber;

an inlet orifice (48, 70) formed on one end fitting, and an outlet orifice (48, 90') formed on the opposite end fitting;

an annular gasket (56, 56') surrounds the bore of the end fitting.

3. The system of claim 2, wherein the desiccant cartridge (40) further comprises:

a shield element (50, 50 ') located on each of said end apertures for retaining said desiccant material (52 ') within said tubular elements (44, 44 '); and

a removable seal (54) for closing the end aperture to prevent moisture from entering the desiccant dryer prior to removal of the seal.

4. The system according to claim 2, characterized in that said end element (60, 62) comprises:

a clamping assembly (42) for receiving the desiccant cartridge (40).

5. The system according to claim 4, characterized in that said clamping assembly (42) comprises:

a piston (98) mounted on one of said end members (60), said piston having a sealing surface (100) for engaging the cartridge liner (56) in sealing relation:

a second gasket sealing face (80) on the other end member (62);

-retracting means (102) for retracting said piston (98) to remove a saturated desiccant cartridge and to receive an unsaturated desiccant cartridge.

6. The system of claim 5, further characterized in that the clamp assembly (42) further comprises:

a spring (104) for biasing the piston (98) into contact with the desiccant cartridge gasket (56); and

wherein the retraction means comprises a manual lever (102) which operates to move the piston towards a spring which retracts it.

7. The system of claim 5 or 6, further characterized by:

an alignment bracket (82, 106) is connected to each end element (60, 62) for aligning the desiccant cartridge gasket with the gasket sealing face (80, 100) of the clamp assembly.

8. The system of claim 1, further characterized by:

the pairs of fittings (72, 92) protrude from the steam generating unit (10) and each have a locking bonding surface (76, 95); and

the locking member (74, 94; 74 ', 94') engages the joint locking surface for locking the end member to the joint.

9. The system of claim 1, further characterized in that the desiccant chamber (44) is removable from the end element (60, 62), the end element comprising:

a piston (98) mounted on one of said end members (60), said piston having a sealing face (100) for engaging one face of said desiccant chamber in sealing relation;

a second sealing surface (80) on the other end element (62); a mechanism (102) for retracting the piston to facilitate removal of a saturated desiccant cartridge and receipt of an unsaturated desiccant cartridge.

10. The system of claim 1, further characterized by:

the desiccant chamber (44, 44') has a moisture absorption capacity that matches the volume of liquid in the peroxygen solution cartridge (12) that is received in the liquid peroxygen solution receiving interface (20).

11. The system of claim 1, further comprising:

a regeneration unit (120) for regenerating the saturated dryer.

12. A method of using the system of claim 1, wherein:

connecting a source of liquid peroxygen solution to the interface of the vaporizer;

vaporizing said liquid peroxygen solution and entraining said vapor in dry air;

supplying steam entrained in the air to a point of use;

returning air and vapor from the point of use through a replaceable desiccant dryer; and

replacing the desiccant dryer when or before it is saturated.

13. The method of claim 12, wherein said desiccant dryer comprises a drum, and wherein said replacing step comprises:

disengaging a saturated desiccant dryer cartridge from a flow path to the vaporizer; and

connecting an unsaturated desiccant dryer cartridge into the flow path to replace the saturated cartridge.

14. The method of claim 13, wherein the source of peroxygen liquid comprises a canister containing a predetermined volume of peroxygen liquid and comprises:

loading the cartridge with an amount of desiccant sufficient to absorb the predetermined volume.

15. The method of claim 13 or 14, further comprising:

regenerating the saturated desiccant cartridge;

attaching a temporary seal to an opening into the cartridge to prevent moisture absorption by the regenerated desiccant; and

opening the seal before connecting the regeneration cartridge.