JP7572814B2 - Ozone generator and method for generating ozone - Google Patents

Description

The present invention relates to an ozone generator equipped with an excimer lamp, etc.

Ozone generators equipped with excimer lamps generate ozone by irradiating oxygen-containing gas or liquid with ultraviolet light, and release the ozone outside the device. This allows for sterilization, deodorization, and other processes.

Ozone is highly reactive with moisture, and irradiating air with low humidity (relative humidity) with ultraviolet light produces ozone more efficiently than irradiating air with high humidity. In addition, the higher the humidity of the environment, the more quickly the generated ozone decomposes into oxygen. For this reason, it is known that in an ozone generator with an excimer lamp arranged in the flow path, ozone can be generated effectively by feeding gas with a humidity of 30% or less into the flow path (see Patent Document 1).

JP 2017-43513 A

Ozone generators may be used for long periods of time (several hours) when performing sterilization and other processes in indoor facilities such as hospital rooms and public facilities. In general indoor environments, the average humidity is high, so if low-humidity gas containing ozone is continuously released from the device, the indoor humidity will decrease. If the rate of ozone decomposition decreases due to a decrease in indoor humidity, more ozone than expected will be generated in the indoor environment, which may have adverse effects on indoor products. In particular, in manned environments, the acceptable ozone concentration is very low due to consideration of the adverse effects on the human body, and the generation of more ozone than expected makes its use difficult.

Therefore, there is a need to provide an ozone generator that can generate ozone in environments with different humidity levels without affecting the outside world.

The ozone generator according to one aspect of the present invention comprises a flow path through which a fluid containing oxygen flows, and a light source that irradiates ultraviolet light and is disposed in the flow path. For example, the light source can be an excimer lamp that emits ultraviolet light having a peak wavelength of 200 nm or less, and the lamp axis can be disposed along the direction of the flow of the fluid. For example, the ozone generator comprises a flow path pipe through which the fluid flows, and also comprises a blower disposed along the flow path.

In the present invention, the ozone generator generates ozone so that the relative humidity difference between the inlet or near the inlet of the flow path and the outlet or near the outlet is equal to or less than a predetermined value. The "predetermined value" can be determined according to the usage environment, such as an unmanned environment or an unattended environment, and is based on, for example, the average humidity in the usage environment, the range of humidity change, etc.

When considering use in an unmanned environment, ozone should be generated so that the relative humidity difference between the inlet or near the inlet and the outlet or near the outlet of the flow path is 30% or less. When considering use in a manned environment, ozone should be generated so that the relative humidity difference between the inlet or near the inlet and the outlet or near the outlet of the flow path is 10% or less.

The ozone generator can generate ozone at or below a predetermined value by configuring the flow path, arranging the light source in the flow path, controlling the light source on, or controlling the air volume of the blower. For example, the light source can be arranged in the flow path so that the distance between the wall of the fluid pipe and the surface of the excimer lamp is greater than the ultraviolet light reach distance at which the ultraviolet light intensity ratio is 10%. In particular, it is sufficient to configure the distance between the wall of the fluid pipe and the surface of the excimer lamp to be at least twice the ultraviolet light reach distance.

The ozone generator may also be configured to include a humidity sensor that detects at least the relative humidity at or near the inlet of the flow path, and the control unit may control at least one of turning on the light source and controlling the air volume of the blower depending on the relative humidity detected by the humidity sensor. The control unit may adjust the air volume of the blower depending on the detected relative humidity, or the control unit may temporarily turn off the light source depending on the detected relative humidity.

In addition, in an ozone generator, if the upper excimer lamp is positioned so that the lamp axis is aligned with the direction of fluid flow, a blower positioned upstream of the excimer lamp can create a non-uniform gas flow around the excimer lamp.

In one aspect of the present invention, an ozone generation method is to place an excimer lamp in a flow path through which an oxygen-containing fluid flows, with the lamp axis aligned with the direction of the fluid flow, and generate ozone so that the relative humidity difference between the inlet or near the inlet and the outlet or near the outlet of the flow path is equal to or less than a predetermined value.

According to the present invention, an ozone generator can generate ozone in environments with different humidity levels without affecting the outside.

1 is a schematic diagram of an ozone generator according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing the periphery of the excimer lamp shown in FIG. 1. FIG. 4 is a diagram showing a flow of ozone generation control by a control unit.

Figure 1 is a schematic diagram of the ozone generator of this embodiment.

The ozone generator 10 includes an excimer lamp 20, a flow tube 30, and a blower 40 in a casing (not shown). The excimer lamp 20 irradiates oxygen-containing gas flowing into one end 30A of the flow tube 30 with ultraviolet light, thereby generating ozone. The ozone-containing gas flows out from the other end 30B of the flow tube 30 (hereinafter referred to as the outlet) and is released outside the device, where it is subjected to sterilization, disinfection, and other processes.

The excimer lamp 20 is arranged coaxially with the flow tube 30 so that its lamp axis E is aligned with the direction of gas flow. The excimer lamp 20 emits ultraviolet light having a peak wavelength of, for example, 172 nm.

An axial fan type blower 40 is arranged coaxially with the flow pipe 30 at the inlet 30A of the flow pipe 30. In addition, a humidity sensor 60 and a humidity sensor 70 are provided near the inlet 30A and the outlet 30B of the flow pipe 30, respectively. The humidity sensor 60 and the humidity sensor 70 detect the relative humidity.

The control unit 50 controls the ozone generation operation in the ozone generator 10, and generates ozone by turning on the excimer lamp 20 and operating the blower 40 in response to input operations by the operator. At the same time, in order to suppress humidity changes in the outflow gas relative to the inflow gas with outside air humidity, ozone is generated so that the difference in humidity between the inlet 30A and the outlet 30B is equal to or less than a predetermined value (%). Specifically, the excimer lamp 20 is switched on/off and the air volume of the blower 40 is adjusted in response to the relative humidity data sent from the humidity sensors 60 and 70.

The allowable range of the relative humidity difference can be determined according to the environment in which the device is used. The decomposition rate of ozone drops significantly when the humidity of the outdoor air indoors falls below 30%, and when used in an unmanned environment, there is no direct impact on people, the relative humidity of the outdoor air indoors is generally around 60%, and the outdoor air humidity is controlled to a certain extent. Based on these factors, ozone can be generated so that the relative humidity difference is 30% or less. By controlling the relative humidity difference in this way, it is possible to prevent excessive ozone from being generated due to a drop in relative humidity.

When used in a manned environment, the ozone concentration in the space must be kept below 0.1 ppm in consideration of the effects on the human body; in a typical indoor space (40 tatami mats or less), the amount of ozone generated must be 10 mg/h or less, and when generating ozone throughout the day, a low-concentration ozone generator (an ozone generator generating 5 mg/h or less) is used; and indoor humidity varies within a range of 40-90% throughout the day. Taking these factors into consideration, ozone should be generated so that the relative humidity difference is 10% or less. More preferably, it should be 5% or less. By controlling the relative humidity difference in this way, the effects on the outside air can be suppressed as much as possible, and the ozone generator 10 can be used continuously for long periods of time even in spaces where only a very low ozone concentration is permitted.

Figure 2 is a schematic diagram showing the surroundings of the excimer lamp 20 in Figure 1.

The distance D from the surface 20S of the excimer lamp 20 to the tube wall 30S of the flow path tube 30 is determined based on the ultraviolet intensity ratio of the ultraviolet rays emitted from the excimer lamp 20. The ultraviolet intensity ratio is expressed as the attenuation ratio at the point where the ultraviolet rays reach when they attenuate as they travel.

Here, the inner diameter R of the flow path tube 30 is determined so that the distance D is greater than the distance d at which the ultraviolet ray intensity ratio from the surface 20S of the excimer lamp 20 becomes 10%. For example, for an excimer lamp 20 that emits ultraviolet rays of 172 nm, the inner diameter R can be determined so that the distance D is at least twice the distance d. In this case, ozone is generated near the surface 20S of the excimer lamp 20, while almost no ozone is generated near the tube wall 30S of the flow path tube 30.

In addition, near the surface 20S of the excimer lamp 20, the relative humidity decreases as the temperature rises while the excimer lamp 20 is on. On the other hand, near the tube wall 30S of the flow path tube 30, which is away from the surface 20S of the excimer lamp 20, the humidity is maintained as it is less affected by the temperature rise.

The blower 40, located upstream of the excimer lamp 20, creates a non-uniform gas flow in the flow tube 30. It creates a complex flow state in which the velocity in the flow direction cannot be expressed as a time average, and also creates a flow such as a swirling flow around the excimer lamp 20. Incidentally, the arrows in Figure 1 simply indicate the flow from the upstream side to the downstream side of the flow tube 30.

As a result, around the excimer lamp 20, the gas near the surface 20S of the excimer lamp 20 and the gas near the tube wall 30S of the flow path tube 30 mix as they pass through, resulting in homogeneous gas with no bias in the amount of ozone generated and relative humidity flowing out from the outlet 30B.

Due to the distance of the excimer lamp 20 from the flow path tube 30 and the formation of a non-uniform flow, it is possible to prevent some gas with a high ozone content from being directly discharged outside the device due to a decrease in humidity caused by the lighting of the excimer lamp 20. Even if the lighting power of the excimer lamp 20 is increased to increase the amount of ozone generated, thereby increasing the amount of ultraviolet radiation and decreasing the humidity near the surface 20S of the excimer lamp 20, it is possible to prevent the relative humidity of the outflowing gas from decreasing excessively.

Furthermore, the ozone generator 10 generates ozone by temporarily turning off the excimer lamp 20 and adjusting the air volume of the blower 40 so that the relative humidity difference does not exceed the allowable range.

Figure 3 shows the flow of ozone generation control by the control unit 50. Here, processing is performed at set time intervals.

The relative humidity difference is calculated based on the relative humidity detected by the humidity sensor 60 installed near the inlet 30A of the flow pipe 30 and the humidity sensor 70 installed near the outlet 30B (S101). Then, it is determined whether the relative humidity difference is equal to or less than a predetermined value (%) (S102). For example, the predetermined value is set to 30% in an unmanned environment, and 10% or 5% in a manned environment.

If the relative humidity difference is equal to or less than the predetermined value, the operation of the blower 40 and the illumination of the excimer lamp 20 are maintained. On the other hand, if the relative humidity difference exceeds the predetermined value, the excimer lamp 20 is turned off for a certain period of time, and the air volume of the blower 40 is increased by a predetermined amount (S103).

By temporarily turning off the excimer lamp 20, the temperature rise near the surface 20S of the excimer lamp 20 is suppressed, and the decrease in relative humidity is suppressed accordingly. In addition, the decrease in relative humidity is suppressed by increasing the air volume in the flow path pipe 30. It is also possible to only execute the on/off control of the excimer lamp 20, or to only execute the air volume control of the blower 40.

To accurately measure the relative humidity at the inlet 30A and outlet 30B, humidity sensors may be provided at the inlet 30A and outlet 30B, or a humidity sensor may be provided upstream of the inlet 30A and downstream of the outlet 30B.

In the above-described control flow for ozone generation, the relative humidity near the inlet 30A and the outlet 30B are measured in real time, but it is also possible to detect only the humidity near the inlet 30A. For example, the relative humidity at the inlet 30A and the outlet 30B can be measured in advance by measurement experiments or simulations while changing the lighting time of the excimer lamp 20, the air volume of the blower 40, the size of the flow path tube 30, the size and placement location of the excimer lamp 20, etc., and data showing the relationship between the relative humidity at the inlet and the relative humidity difference can be stored in a memory or the like.

The control unit 50 can estimate the relative humidity difference from the relative humidity detected near the inlet 30A based on the data stored in the memory. In addition, by providing a humidity sensor only near the inlet 30A, damage to the sensor and malfunction due to the generated ozone can be prevented.

On the other hand, ozone generation control may be performed using feedforward control rather than feedback control by obtaining the relationship between the time elapsed since the excimer lamp 20 started to be turned on and the change in the relative humidity difference through experiments, etc. For example, it is possible to periodically turn off the excimer lamp 20 before the relative humidity difference exceeds a predetermined value. In addition, the blower 40 may be controlled to periodically increase the air volume for a predetermined period of time.

Depending on the size and shape of the device and excimer lamp 20, the amount of ozone required to be generated, etc., it may be difficult to ensure a sufficiently long distance between the tube wall 30S of the flow path tube 30 and the surface 20S of the excimer lamp 20. In such cases, ozone generation control that suppresses the relative humidity difference can be performed by turning off the excimer lamp 20 and/or adjusting the air volume of the blower 40. It is also possible to configure the excimer lamp 20 so that the lamp axis is not aligned with the axis of the flow path tube 30.

The distance D between the surface 20S of the excimer lamp 20 and the tube wall 30S of the flow path tube 30 is determined according to the reach distance d corresponding to the ultraviolet light intensity ratio, but it is possible to configure the distance D to be shorter due to restrictions on the device size and flow path tube size, and it is not necessary to intentionally create a non-uniform gas flow using the blower 40. It is also possible to configure the lamp axis not to be aligned with the tube axis of the flow path tube 30. The blower 40 can also be placed downstream of the excimer lamp 20 or away from the flow path tube 30.

Instead of the excimer lamp 20, other light sources (such as LEDs) that emit ultraviolet light may be used. In this case, by changing the emission intensity, ozone can be generated with relative humidity differences suppressed. The wavelength of the ultraviolet light can be appropriately determined depending on the application. It is also possible to supply a multiphase flow that contains not only gas such as oxygen, but also particles, powder, or liquid, into the flow tube 30.

As described above, in the ozone generator 10 of this embodiment, ozone generation is controlled so that the relative humidity difference between the relative humidity near the inlet 30A of the flow path pipe 30 and the relative humidity near the outlet 30B falls within an allowable range. By generating ozone so that the humidity of the gas released outside the device does not differ significantly from the outside air humidity, it is possible to suppress the generation of ozone that exceeds expectations. This effect is particularly noticeable in humid environments.

10 Ozone generator 20 Excimer lamp (light source)
30 Flow path pipe 40 Blower 50 Control unit 60, 70 Humidity sensor

Claims (10)

A flow path through which a fluid containing oxygen flows;
A light source that irradiates ultraviolet light and is disposed in the flow path;
A blower provided along the flow path;
a humidity sensor for detecting a relative humidity at an inlet or in the vicinity of the inlet and at an outlet or in the vicinity of the outlet of the flow path;
a control unit that performs at least one of turning on the light source and controlling the air volume of the blower in response to the relative humidity detected by the humidity sensor so that a relative humidity difference between an inlet or the vicinity of the inlet and an outlet or the vicinity of the outlet of the flow path is equal to or less than a predetermined value. The ozone generator according to claim 1, characterized in that ozone is generated so that the relative humidity difference between the inlet or near the inlet and the outlet or near the outlet of the flow path is 30% or less. The ozone generator according to claim 1 or 2, characterized in that ozone is generated so that the relative humidity difference between the inlet or the vicinity of the inlet and the outlet or the vicinity of the outlet of the flow path is 10% or less. The light source is an excimer lamp that emits ultraviolet light having a peak wavelength of 172 nm,
A fluid conduit is further provided to define the flow path.
4. The ozone generator according to claim 1, wherein the distance between the wall of the fluid pipe and the surface of the excimer lamp is greater than the ultraviolet light reachable distance at which the ultraviolet light intensity ratio is 10%. The ozone generator according to claim 4, characterized in that the distance between the wall of the fluid pipe and the surface of the excimer lamp is at least twice the reachable distance of the ultraviolet light. The excimer lamp is disposed so that the lamp axis is aligned with the direction of the fluid flow;
a blower disposed in the flow path upstream of the excimer lamp,
6. The ozone generating device according to claim 4, wherein the blower forms a non-uniform gas flow around the excimer lamp. A flow path through which a fluid containing oxygen flows;
A light source that irradiates ultraviolet light and is disposed in the flow path;
A blower provided along the flow path;
a humidity sensor for detecting a relative humidity at least at an inlet of the flow path or near the inlet;
a control unit that performs at least one of turning on the light source and controlling the air volume of the blower in response to the relative humidity detected by the humidity sensor so that a relative humidity difference between an inlet or the vicinity of the inlet and an outlet or the vicinity of the outlet of the flow path is equal to or less than a predetermined value. The ozone generator according to claim 7, characterized in that the control unit adjusts the air volume of the blower according to the detected relative humidity. The ozone generator according to claim 7 or 8, characterized in that the control unit temporarily turns off the light source depending on the detected relative humidity. An excimer lamp is disposed in a flow path through which a fluid containing oxygen flows, with the lamp axis being aligned along the direction of the flow of the fluid;
A blower is disposed along the flow path;
A humidity sensor is disposed to detect the relative humidity at least near the inlet or outlet of the flow path;
a control unit that determines whether a relative humidity difference between an inlet or the vicinity of the inlet of the flow path and an outlet or the vicinity of the outlet is equal to or less than a predetermined value, and if the difference exceeds the predetermined value, performs at least one of controlling the lighting of the excimer lamp and controlling the air volume of the blower.

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