HK1192532B - Ozone-based disinfecting device comprising a flow sensor - Google Patents

Description

Ozone type disinfection apparatus comprising a flow sensor

Technical Field

The present invention relates to an ozone-based disinfection apparatus of a general nature, wherein in use the apparatus produces a water spray having an effective and suitable amount of ozone embedded therein. More particularly, the invention relates to an ozone-type disinfection apparatus suitable for use in connection with food products, but which may be used in many other applications.

Still more particularly, the present invention relates to a disinfection apparatus of the general nature described in our earlier published international patent application WO 2010/001279.

Background

Microbial products are of major concern between the food processing industry and consumers. The presence of pathogenic microorganisms on food can potentially lead to food-borne disease outbreaks.

Chlorine-based chemicals such as sodium hypochlorite, calcium hypochlorite, sodium dichloroisocyanurate, and quaternary ammonium compounds have been used in the past to disinfect food. However, chlorine is most effective at a pH of 6 to 8, and the effect becomes lower outside this pH range. Moreover, chlorine can produce toxic by-products harmful to human health, such as chloramines and trihalomethanes.

Thus, the european union has forced the ban on the use of chlorine compounds to disinfect foods, as specified by EU directive 2092/91. Efforts have thus been coordinated to improve the technology of utilizing non-chlorine based products for food processing for sterilization. Which has attracted increased interest in ozone disinfection properties. The use of ozone to sterilize food has been approved by the U.S. Food and Drug Administration (FDA).

Notably, ozone is reported to have an oxychlorination potential of about 1.5 times less, typically four to five times less, than chlorine for its antimicrobial effect.

Ozone has been shown to be a highly active oxidant, capable of killing microorganisms such as bacteria, and reacting with other chemicals, such as pesticides and herbicides. Of course, the main advantage of ozone is its natural decomposition into oxygen, and its use in disinfecting food is therefore very beneficial due to its decomposition into non-toxic gases. Thus, no odor is emitted or food is contaminated and no residual compounds or toxic residues remain. The rinse water can be discharged to the environment or used for other applications without additional treatment and decontamination.

In the prior art, disinfection processes known to the applicant which utilize ozone, venturi injection systems and bubble diffusers have been used to mix ozone with water. In the case of a venturi ejector, water is forced through a converging cone, inducing a pressure differential between the inlet and outlet of the system. This creates a vacuum inside the body of the injector, thereby initiating an ozone-enriched air flow through the air inlet.

As for the bubble diffuser, the ozone-rich air is emitted as bubbles under the water surface. Despite the further problems identified below, bubble diffusers have inherent disadvantages that reduce system efficiency as the diffuser holes tend to become fouled over time.

In both cases, ozone, typically from ozone-enriched air, is dissolved in the water, and the water itself can be disinfected with an appreciable proportion of the sterilizing capacity of ozone. This reduces the amount of ozone available to effectively disinfect the final target, which may be fresh produce, for example.

In addition, these prior art systems appear to allow free gaseous ozone to be released into the atmosphere at higher concentrations than permitted by regulatory standards. Notably, free ozone in the air is harmful when the free ozone exceeds a predetermined concentration.

In this regard, it is noteworthy that in the European Union, the current target value for ozone concentration is reported to be 120 μ g/m³And is about 60 nmol/mol. Although there is no data set to formally make it a requirement, this goal applies to all member countries according to instruction 2008/50/EC, and it is treated as a long-term goal. In the united states, in 5 months 2008, the Environmental Protection Agency (EPA) reduced its ozone standard from 80nmol/mol to 75 nmol/mol. Despite the fact that the institution's own scientists and advisor committees have suggested reducing the standard to 60 nmol/mol. The EPA has established an air quality index to help explain air pollution levels to the public and currently current standards describe an eight hour average ozone mole fraction of 85 to 104nmol/mol as "unhealthy to sensitive groups"; 105 to 124nmol/mol are described as "unhealthy"; and 125nmol/mol to 404nmol/mol are described as "very unhealthy". The world health organization recommends 51 nmol/mol.

Therefore, excess ozone in the air is highly undesirable, and importantly, any disinfection device that utilizes ozone as its active disinfection medium should not release any appreciable amount of ozone into the atmosphere while providing an effective concentration to destroy target bacteria and the like.

In our earlier international patent application identified above, a proposal for sensing the flow of water through a mixer is to monitor the pressure increase in the mixer as water is applied to the mixer under pressure. This expedient does not operate efficiently and requires investigation of alternative controls.

Disclosure of Invention

According to the present invention there is provided an ozone-type disinfection apparatus comprising a mixer having a substantially hollow body, and a water inlet for water under pressure; a spray nozzle for generating a substantially conical spray of water introduced through the water inlet; a contact chamber in communication with a gas inlet for ozone-enriched gas; a contact chamber outlet aperture coaxial with and spaced from the spray nozzle, and a flow sensing device for sensing the degree of flow of water through the spray nozzle, the ozone-based disinfection device being characterized by: the flow sensing device is an electronic flow sensing device for sensing vibrations caused by the flow of water through the mixer.

Further features of the invention provide an electronic flow sensing device located in a pocket formation (pocket) of the mixer body; an electronic flow sensing device comprising a piezoelectric sensor and suitable associated circuitry for generating a signal indicative of the flow rate of water through the mixer; and a piezoelectric sensor embedded in the curable material and having a generally disc shape with a thin, smaller diameter, compressible disc and coaxially adhered to both surfaces of the sensor disc, the outer diameter of the piezoelectric sensor being firmly embedded in the curable material, and wherein an aperture in the center of one of the discs provides the curable material to contact the piezoelectric sensor on one side thereof in a central region.

Still further features of the invention provide for the associated circuitry to be carried on a printed circuit board housed within the mixer body; a printed circuit board accommodated in the pocket-shaped configuration of the mixer body; a flow sensing device and associated circuitry arranged to activate and deactivate an ozone generator operatively connected to the ozone gas enriched gas inlet; signals output by a flow sensing device and associated circuitry operable to activate and deactivate a fan supplying air to the ozone generator, the fan activation being effected before activation of the ozone generator occurs and the fan deactivation being effected after deactivation of the ozone generator occurs; and a fan capable of operating at different speeds depending on the flow rate of water through the spray nozzle.

An additional feature of the invention provides that the diameter of the outlet orifice substantially corresponds to the diameter of the conical spray at that location, such that, in use, substantially no free space exists between the exterior of the conical spray and the periphery of the outlet; a contact chamber, itself having a cross-sectional dimension greater than the diameter of the outlet orifice; and a gas inlet for ozone-enriched gas having an axis parallel to but laterally offset from the water inlet, the gas inlet chamber merging laterally with the contacting chamber.

The mixer body is preferably composed of a first part in the form of a shroud defining an outlet aperture, and a second part receiving at an open end opposite the outlet aperture a water inlet, a gas inlet and a pocket formation for receiving an electronic flow sensing device which senses the degree of flow of water through the spray nozzle, the second part of the body being received in a plug-like manner in the open end of the body shroud.

The water inlet is preferably configured as a threaded socket for direct application to a complementary threaded pipe (spout) of a faucet (tap) or other tubular water dispenser.

According to a second aspect of the present invention, there is provided an ozone-based disinfection apparatus comprising a mixer as defined above; an ozone generator operatively connected to the ozone-enriched gas inlet for use in the mixer; and control circuitry connected to the flow sensing device and any associated circuitry, wherein the control circuitry is configured to: the ozone generator is activated upon receiving from the flow sensing device and any associated circuitry a signal corresponding to a minimum flow rate of water through the mixer required to produce (develop) from the contact chamber a suitable water injection cone occupying the exit orifice, and deactivated upon receiving a signal corresponding to less than said minimum flow rate.

It should be noted that the practice of the present invention results in ozone-rich gas being entrained with numerous sprayed water droplets, and it is believed that without any appreciable proportion of ozone being dissolved in the water, the ozone will in some way, perhaps electromagnetically or electrostatically, adhere itself to the water droplet surfaces. This theory explains the practical measurements that have shown to date that more ozone is carried by water rather than being generally dissolved in water. Tests carried out to date have also revealed that there is essentially no free ozone in the air surrounding the disinfecting spray and that there is little or no ozone residue in the used water. The practice of the present invention clearly achieves optimal utilization of ozone and enables it to be highly effective in its germicidal action.

Although the mechanism of adhesion or other means of ozone molecules to the sprayed water droplets is not fully understood or fully technically studied, tests conducted to date have shown that the droplet size produced by spraying is preferably between 10 and 50 microns and that the water spray cone preferably has a cone angle between 35 ° and 45 °. In addition, the pressure drop created by the flow generated by the fan and by the flow of the conical spray outside the outlet orifice results in a slightly negative pressure of the order of 10 mm (100 pa) holding water within the contact chamber. In this respect, further testing will involve determining whether it is practical to completely remove the fan, which will depend largely on the negative pressure generated within the contact chamber and the nature of the flow path through the ozone generator to the mixer.

In order that the above and other features of the invention may become more apparent, an embodiment including all of the various aspects of the invention will now be described with reference to the accompanying drawings.

Drawings

In the figure:

FIG. 1 is a schematic view of various components of an ozone-based disinfecting device according to the present invention;

FIG. 2 is a schematic representation of an ozone generator for use in the apparatus shown in FIG. 1 with its cover removed;

FIG. 3 is a similar view of the ozone generator with certain components removed to reveal other components;

FIG. 4 is an exploded perspective view of the mixer shown in FIG. 1;

FIG. 5 is a cross-sectional view of the mixer shown in FIGS. 1 and 4;

FIG. 6 is a plan view of the mixer;

FIG. 7 is a block circuit diagram of the circuitry of the piezoelectric detection circuit; and

fig. 8 is a graph showing the output from a piezoelectric sensor and associated circuitry and the change in water pressure versus flow rate through the mixer.

Detailed Description

In the embodiment of the invention shown in the figures, the ozone-type disinfection apparatus comprises a mixer (2), the mixer (2) having a substantially hollow body and a threaded socket (3) as a water inlet for water under pressure, the socket being adapted to be directly connected to a threaded outlet from a water supply tap (4) or some other water supply apparatus having a tubular outlet.

The axis of the ozone-enriched gas inlet (5) is parallel to but laterally offset from the axis of the water inlet of the gas inlet chamber (6), the gas inlet chamber (6) laterally merging with a further generally cylindrical contact chamber (7) surrounding the water inlet. The mixer has a spray nozzle (8) (see fig. 4) comprising a swirler (9) for generating a generally conical spray (11) (see fig. 5) of water introduced through the water inlet such that the conical spray enters the contacting chamber directly and towards a coaxial reduced diameter outlet orifice (12) spaced therefrom. The contact chamber itself has a cross-sectional dimension that is larger than the diameter of the outlet orifice. The spray nozzle is coaxial with the water inlet and the nozzle itself is generally centrally located in the contacting chamber.

The diameter of the outlet orifice substantially corresponds to the outer diameter of the conical spray at this distance from the nozzle, so that substantially no free space exists between the outside of the conical spray and the periphery of the outlet. In practice, in use, the outer periphery of the conical spray may be slightly interrupted (cutoff) by the outlet orifice periphery, but care should be taken that this extent should not cause larger droplets to coalesce at the outlet periphery.

As for the mixer body construction, it conveniently consists of a first part (15) in the form of a shroud defining an outlet aperture, and a second part (16) receiving the second part (16) defining the water inlet, the gas inlet and a pocket formation (17) between the water and gas inlets at an open end opposite the outlet aperture. In this case, the lateral merging of the gas inlet chamber and the contact chamber occurs laterally and below the pocket-like configuration.

As is most apparent from fig. 4 of the drawings, the second part of the body is received in a plug-like manner in the open end of the hood portion of the body. The first and second portions of the mixer body may be injection molded or transfer molded from a suitable ozone resistant material and the two portions may be permanently sealed together in any suitable manner, including ultrasonic welding, solvent welding, and adhesives. The pocket-like configured opening may be closed by a suitable closure (18) having its own flexible grommet (19) as shown in fig. 4.

The mixer includes a flow sensing device in the form of a piezoelectric sensor (21) connected to associated circuitry in the form of an electronic signal generating printed circuit board (22), the electronic signal generating printed circuit board (22) being for amplifying the signal produced by the piezoelectric sensor and providing an output suitable for operating control circuitry described further below.

In order to ensure that the piezoelectric sensor is adequately actuated by the water through the vibrations created by the mixer, the piezoelectric sensor itself and its associated circuitry in the form of a printed circuit board (22) are received within a pocket (17) of the mixer body and the remaining space within the pocket is filled with a suitable curable material. Thus, the curable material will ensure that the generated vibrations are correctly transmitted to the piezoelectric sensor.

In one successful arrangement of a piezoelectric sensor, which has a disc shape, a thin, smaller diameter compressible, in this example a foam material (foam), a disc (23) is attached coaxially to both surfaces of the sensor. The smaller outer diameter of the foam disc enables the outer perimeter of the piezoelectric sensor to be securely embedded in the curable material. A small hole (24) (see fig. 4) in the center of the foam disc closer to the socket allows the settable material to contact the piezoelectric sensor in a central area on one side thereof. The effect is that a piezoelectric sensor held fast at its periphery and excited by small columns of curable material (denoted by the numeral (24 a) in figure 5) occupying small holes (24) exhibits enhanced motion due to the fact that the foam material allows the piezoelectric sensor to enhance vibration and accordingly output therefrom.

Of course, the piezoelectric sensor is sensitive to vibrations caused by the water as it passes through the nozzle, and the vibrations will generally vary in frequency with the flow velocity of the water. Fig. 8 is a graph illustrating the variation of flow rate with pressure and the output of a piezoelectric sensor and associated circuitry.

The microprocessor (41) is preferably included on a printed circuit board and it enables other intelligent electronic sensors to be incorporated into the mixer circuit, such as an infrared proximity sensor (42) for opening the nozzle and for connecting to a solenoid controlled water valve which in this example may open the water flow itself. Thus, the sensor can be used to turn on ozone flush water, for example, in a urinal.

An example of an electronic circuit is shown in block diagram form in fig. 7 for completeness only. It can be noted that the output from the piezoelectric sensor passes first through a low pass filter (43) and then through an amplifier (44). The amplified signal passes through a high pass filter (45), then a rectifier (46) and then a low pass filter (47). Of course, the electronic circuitry may include a Light Emitting Diode (LED) (48) to indicate when the vibration sensor is activated. Also the additional function of the LED in the mixer, or a further LED, may communicate other information to the user, for example by flashing the display interval every 15 seconds, to assist in correctly dosing the laundry. It may also indicate an error or cell failure by flashing a sequence of red (as opposed to green or blue) lights. It is further described below that the printed circuit board may be provided with a communication connector (49) to the ozone generator.

A separate ozone generator (25), of generally known construction and of corona discharge type, is operatively connected to the gas inlet for ozone-enriched gas to the mixer (5) by means of a suitable pipe (26). However, the ozone generator is modified to operate in accordance with the present invention and to house the control circuitry on a printed circuit board (27) (see fig. 3) within the ozone generator housing.

The ozone generator is also connected to the mixer by a communication cable (28) for supplying the printed circuit board (22) and the piezoelectric sensor (21) in a pocket configuration within the mixer with electrical energy at a low DC voltage and converting the generated signal to a control circuit in the ozone generator housing in response to the piezoelectric sensor.

The control circuit incorporates a suitable transformer and rectifier for connection to the mains electricity supply outlet by a suitable cable (31). The control circuit is configured to actuate a corona discharge ozone generator unit (32) upon receiving a signal from the mixer corresponding to a minimum predetermined flow rate through the mixer that will correspond to the water producing the water spray cone occupying the outlet aperture of the contact chamber. The control circuit similarly deactivates the ozone generator unit once the signal received from the mixer corresponds to less than said minimum flow rate. It will be appreciated that in this way ozone generation in the absence of sufficient flow of water through the mixer can be avoided and therefore cannot be released into the atmosphere.

In this embodiment of the invention, the ozone generator further comprises a variable speed centrifugal fan (33) for blowing air through the ozone generator and then into the contact chamber of the mixer. The centrifugal fan has a substantially conventional centrifugal impeller (34) driven by a variable speed DC motor (35). In response to signals received from the piezoelectric sensor, the variable speed electric motor is controlled by the control circuit such that the fan is activated before activation of the ozone generator occurs and the fan is deactivated after deactivation of the ozone generator occurs.

In use, as the spray passes through the contact chamber and is ejected from the outlet orifice, a spray of sterilizing water is generated which carries ozone as the active sterilizing agent, such that the ozone is carried away from the outlet with the spray, as described above.

The operation of the disinfection apparatus is started by opening the tap, causing water to flow through the mixer and once the flow rate reaches its minimum level, in this example about 1.3 litres per minute, and preferably between 1.6 and 2 litres per minute, the control circuit will first start the DC motor which drives the fan to generate an airflow over the corona discharge unit (32) and shortly thereafter the high voltage circuit of the corona discharge unit is energised to start generating ozone. This procedure was performed to ensure that all ozone generated was carried through to the mixer. The control circuit may also activate an indicator light, such as a blue LED, to indicate that air is flowing and ozone is being generated.

When the faucet is turned further on, a piezoelectric sensor in the spout causes an increased flow signal to be sent to the control circuit, which adjusts the fan speed to increase airflow in response to increased water flow. Thus, the disinfection device has the ability to sense the water flow rate and supply an increased amount of ozone to the mixer as the water flow rate increases.

The mixed ozone and water exit the nozzle in fine droplets/spray and hit the target being placed or treated in the wash water spray.

Thus, air is blown by the fan through the corona discharge unit at a speed that varies according to the signal received from the piezoelectric sensor and its associated circuitry. In this regard, it should be noted that the piezoelectric sensor senses the vibration generated by the path of the water through the swirler and the mixer nozzle, and the vibration characteristics will vary with the flow rate of the water through the mixer.

By way of example only, in the test equipment employed, the following pressures result in the (steady) flow rates of water and fan speed and the ozone content of the water:

notwithstanding the foregoing, it should be noted that it is also contemplated that the slightly reduced pressure created in the mixing chamber by the spray moving therethrough may be sufficient to cause satisfactory flow of air through the ozone generator, rendering the fan and its associated controls unnecessary, with consequent cost savings. However, in this case, the water supply pressure should be relatively uniform within the predetermined practical range achievable by the water mains.

Many variations and applications exist with the present invention. Thus, for example, the portable unit can be produced as a self-contained shoulder unit with a water reservoir, a battery pack and an atomizing spray gun. The user may walk in a gymnasium or other large area facility area where disinfection cannot tolerate large amounts of water.

The nozzle may be connected to a dishwasher in order to provide a constant disinfecting spray during the washing process. This arrangement may allow the dishwasher to have a reduced operating temperature, thereby saving power.

The nozzle may be attached to a shelf spray type system to produce a gentle cooling spray on the fresh produce for cooling and disinfection in many locations such as markets, transport vehicles, or any other suitable environment.

The apparatus may be used in a tunnel with a conveyor and a plurality of nozzles may be spaced along the length of the tunnel for bulk items to be sterilized. This arrangement can be used for packaging crates for sterilized fish or any other fresh produce packaging crate. The system may also be used to disinfect and remove pesticides from bulk fresh produce in a packaging plant.

The disinfection device may be connected to a urinal for spraying ozone-enriched water into the urinal when flushing. In this way bacteria and odor can be reduced.

The unit may be, for example, an under-the-counter or wall mounted unit associated with a dedicated wash basin. There are many variations of the invention without departing from the scope of the invention.

Claims (14)

1. An ozone-type disinfection apparatus comprising a mixer having a hollow body comprising a water inlet for pressure, a spray nozzle, a contact chamber and a flow sensing apparatus; wherein the spray nozzle is for generating a conical spray of water introduced through the water inlet; a contact chamber communicating with a gas inlet for ozone-rich gas and a spray nozzle coaxial with the water inlet, the nozzle being centrally located in the contact chamber; a reduced diameter outlet orifice of the contacting chamber, coaxial with and spaced from the spray nozzle, and such that a conical spray enters the contacting chamber directly and towards the outlet orifice; and a flow sensing device, which is an electronic flow sensing device for sensing vibrations caused by the flow of water through the mixer.

2. An ozone-type disinfection apparatus as claimed in claim 1, wherein said electronic flow sensing device is located in a pocket-like formation provided in said mixer body.

3. An ozone-based disinfecting device as claimed in either one of claims 1 or 2 in which the electronic flow-sensing device comprises a piezoelectric sensor and associated circuitry for generating a signal indicative of the flow rate of water through the mixer.

4. An ozone-type sterilizing apparatus as claimed in claim 3, wherein said piezoelectric sensor is embedded in a curable material and has a disk shape with a thin, smaller diameter, compressible disk coaxially adhered to both surfaces of the sensor disk, the outer diameter of said piezoelectric sensor being firmly embedded in the curable material, and wherein a small hole in the center of one disk is used to supply the curable material so as to contact said piezoelectric sensor on one side thereof in the central area.

5. An ozone-based disinfecting device as claimed in claim 3 in which the associated electrical circuit is carried on a printed circuit board housed within the mixer body.

6. An ozone-type sterilizing apparatus as claimed in claim 5, wherein said printed circuit board is housed in a pocket-like formation of said mixer body.

7. An ozone-type disinfection apparatus as claimed in claim 3 wherein said flow sensing apparatus and associated circuitry are arranged to activate and deactivate an ozone generator operatively connected to said gas inlet for ozone-enriched gas.

8. An ozone-based disinfecting device as claimed in claim 7 in which the signals output by the flow sensing device and associated circuitry are operable to activate and deactivate a fan supplying air to the ozone generator, the fan activation being effected before activation of the ozone generator occurs and the fan deactivation being effected after deactivation of the ozone generator occurs.

9. An ozone-based disinfecting device as claimed in claim 8 in which the fan is capable of operating at different speeds depending on the flow rate of water through the spray nozzle.

10. An ozone-based disinfecting device as claimed in claim 1, in which the diameter of the outlet aperture corresponds to the diameter of the conical spray, so that in use no free space exists between the outside of the conical spray and the periphery of the outlet.

11. An ozone-based disinfecting device as claimed in claim 1, in which said contact chamber itself has a cross-sectional dimension which is greater than the diameter of said outlet aperture.

12. An ozone-based disinfecting device as claimed in claim 1 in which the axis of said gas inlet for ozone-enriched gas is parallel to but laterally offset from the axis of said water inlet, and a gas inlet chamber merges laterally with said contacting chamber.

13. An ozone-based disinfection apparatus as claimed in claim 1, wherein said mixer body is comprised of a first part in the form of a shroud defining said outlet aperture, a second part receiving at an open end opposite said outlet aperture a second part defining said water inlet, gas inlet and a pocket formation for receiving said electronic flow sensing device sensing the degree of flow of water through said spray nozzle, said second part of said body being received in a plug-like manner in said open end of said shroud of said body.

14. An ozone-type disinfection apparatus as claimed in claim 13 wherein said water inlet is configured as a threaded socket for direct application to a complementary threaded tube of a faucet or other tubular water dispenser.