JP2003059453A - Liquid treatment device and method by ultraviolet ray - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the formation of peroxide easily generated when performing decomposing treatment of an organic substance in liquid by an ultraviolet ray of a short wave length area of 220 nm or less. SOLUTION: An ultraviolet ray radiated from a discharge lamp for emitting an ultraviolet ray of 220 nm or less and an ultraviolet ray of 254 nm so as to coexist is applied to a treating object liquid to perform the decomposing treatment of the organic substance in the liquid. An object by forming a thin film of metallic oxide on an arc tube inside surface is used as this discharge lamp to prevent adsorption of mercury oxide formed at discharge lamp lighting time to the arc tube inside surface as well as to restrain reduction in illuminance with the lapse of time of the ultraviolet ray of 254 nm. Since the ultraviolet ray of 254 nm contributes to decomposing the peroxide, maintenance of the illuminance with the lapse of time of the ultraviolet ray of 254 nm restrains a formation quantity of the peroxide in a treating object liquid over a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid processing apparatus and method for performing processing such as decomposition of organic matter in a liquid by using a discharge lamp that co-radiates short wavelength ultraviolet light of 220 nm or less and 254 nm ultraviolet light. .

[0002]

2. Description of the Related Art Ultraviolet rays in a short wavelength region of 220 nm or less have strong energy and are therefore used in various fields such as decomposition of harmful substances and organic substances. FIG. 10 shows an example of a conventionally known closed type ultraviolet irradiation apparatus for liquid treatment.
What stored the discharge lamp 30 in the outer tube (protection tube) 20 is
It is contained in a cylinder 1 made of stainless steel, the liquid to be treated is introduced into the cylinder 1, and the ultraviolet rays emitted from the discharge lamp 30 are irradiated. As the discharge lamp 30, for example, 1
A low pressure mercury vapor discharge lamp is used which emits both 85 nm short wavelength UV and 254 nm wavelength UV. The arc tube bulb 10 of the discharge lamp 30 is made of quartz glass, which has an excellent UV transparency. The discharge lamp 30 is housed inside an outer tube (protection tube) 20 that is transparent to ultraviolet rays, and the discharge lamp 30 is liquid-tightly isolated from the liquid to be treated. Such outer tube 2
No. 0 is also made of quartz glass having excellent ultraviolet light transmittance. Both ends of the cylinder 1 are closed by flanges 1a and 1b, and the liquid to be treated introduced from the water inlet 1c is irradiated with ultraviolet rays while passing through the cylinder 1, and is discharged from the water outlet 1d. The liquid to be treated flows in the cylinder 1 from the water inlet 1c to the water outlet 1d, but a plurality of (five in the figure) reflux plates 1e to It has a structure in which 1i is arranged. Note that, for convenience, FIG. 10 illustrates a device in which only one discharge lamp 30 is mounted, but in practice, a multi-lamp large-capacity device is often used. The ultraviolet rays emitted from the discharge lamp 30 pass through the outer tube 20 and are applied to the liquid to be treated. The irradiated ultraviolet rays have a function of decomposing organic matter existing in water into harmless CO, CO ₂ and H ₂ O as shown in the following formula.

H ₂ O + hν (185 nm) → H + OH radical C _n H _m O _k + OH radical → CO, C
O ₂ , H ₂ O (n, m, k, is 1, 2, 3, ...)

The decomposition of this organic substance is due to the action of ultraviolet rays in the short wavelength region of 185 nm. However, the excessive amount of ultraviolet rays in the short wavelength region is caused by various unintended effects such as hydrogen peroxide (H ₂ O ₂ ). The oxide forms as an intermediate. In order to remove such a peroxide, a step of passing the liquid to be treated, which has been subjected to the ultraviolet ray irradiation treatment, through the ion exchange resin in the latter stage of the ultraviolet ray irradiation treatment. Therefore, these peroxides are removed when the liquid to be treated passes through the ion exchange resin, but excess peroxide causes deterioration of the life of the ion exchange resin.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a liquid treatment apparatus and method by ultraviolet rays capable of performing liquid treatment capable of suppressing generation of peroxide as much as possible. It is the one we are trying to provide. Further, along with this, it is possible to extend the life of the ion exchange resin used in the latter stage of the ultraviolet irradiation treatment, and to provide a liquid treatment apparatus and method of long life, energy saving and maintenance saving.

[0006]

The liquid treatment apparatus using ultraviolet rays according to the present invention is provided with ultraviolet rays of 220 nm or less and 254 n.
In a liquid treatment apparatus for irradiating the liquid to be treated with ultraviolet rays emitted from a discharge lamp that co-emits ultraviolet rays of m, for decomposing organic matter of the liquid, the discharge lamp is provided with metal oxide on its inner surface. It is characterized by using a discharge lamp formed by forming a thin film. According to the present invention, by forming a thin film of a metal oxide on the inner surface of an arc tube of a discharge lamp, it is possible to prevent mercury oxide generated during lighting of the discharge lamp from being adsorbed on the inner surface of the arc tube. It is possible to suppress a decrease in illuminance.

In a discharge lamp that co-emits 220 nm or less ultraviolet rays and 254 nm ultraviolet rays, the ultraviolet rays in the wavelength range of 220 nm or less participate in the photochemical treatment for decomposing organic substances. On the other hand, ultraviolet rays in the wavelength region of 254 nm play an important role in decomposing the peroxide which is an intermediate, and reduce the burden on the ion exchange resin used in the latter stage of the ultraviolet irradiation treatment. By the way, the ultraviolet illuminance of the discharge lamp decreases with the lapse of use time, but in the short wavelength range of 220 nm or less and the 254 nm range of ultraviolet light,
Different causes of UV illumination reduction. The decrease in UV illuminance in the short wavelength range of 220 nm or less is caused by the fact that the quartz glass forming the tube body of the discharge lamp is exposed to UV rays to be deteriorated and the UV transmittance is lowered. On the other hand, the decrease in the illuminance of ultraviolet rays in the wavelength region of 254 nm is caused by the fact that the oxygen generated in the tube during the lighting of the discharge lamp reacts with mercury and the generated mercury oxide is adsorbed on the inner surface of the quartz glass, and the ultraviolet ray of the quartz glass is transmitted. This is due to the decrease in the rate. Therefore, as shown in FIG. 9, the ultraviolet illuminance maintaining characteristics are different between the ultraviolet rays in the short wavelength range of 220 nm or less and the ultraviolet rays in the wavelength range of 254 nm.
Since the decrease in illuminance of ultraviolet rays of nm is faster, the maintenance rate of 254 nm in FIG. 9 is 220 nm or less (for example,
185 nm) below the UV illuminance maintenance rate, after the point C,
It is considered to cause an increase in peroxide. On the other hand, according to the present invention, by forming a thin film of a metal oxide on the inner surface of the discharge tube of the discharge lamp, it is possible to prevent the mercury oxide generated during lighting of the discharge lamp from adsorbing on the inner surface of the discharge tube. 254n
It is possible to suppress a decrease in the illuminance of ultraviolet rays of m.

Further, the liquid treatment apparatus using ultraviolet rays according to the present invention irradiates the liquid to be treated with ultraviolet rays emitted from a discharge lamp which co-emits ultraviolet rays of 220 nm or less and 254 nm, and decomposes the organic matter of the liquid. In the liquid processing apparatus, the discharge lamp of the discharge lamp uses natural quartz or silica sand as a starting material, and the total content of elements consisting of four kinds of sodium, potassium, titanium and iron is 2. A discharge lamp is used which is made of quartz glass containing 5 ppm or less and 10 ppm or more of OH groups, and a metal oxide thin film is formed on the inner surface of the arc tube.

Quartz glass made from natural quartz or silica sand as a starting material contains various substances as impurities. Among these impurities, sodium (N
The abundance of the four elements a), potassium (K), titanium (Ti) and iron (Fe) causes a decrease in the transmittance of the quartz glass. On the other hand, the presence of OH groups can alleviate the alteration of quartz glass. That is, “S” of silicon dioxide (SiO ₂ ) which is the main component of quartz glass
The bond of "i-O" is decomposed by the ultraviolet energy to generate free Si which causes a decrease in transmittance.
Can be suppressed. As a result of experiments and research by the inventor, the total content of these four elements is 2.5.
It has been found that when the OH group content is less than or equal to ppm and more than or equal to 10 ppm, deterioration with time of the quartz glass due to ultraviolet rays in the short wavelength range can be considerably improved. Therefore, by selecting or setting the material of the quartz glass in such a manner, it is possible to increase the illuminance maintenance rate of ultraviolet rays in the short wavelength region of 220 nm or less, and to improve the metal oxide on the inner surface of the arc tube of such a high-performance discharge lamp. By forming a thin film of 254 nm
The effect of suppressing the decrease in the illuminance of ultraviolet rays is further exerted.

Further, the liquid treatment apparatus using ultraviolet rays according to the present invention irradiates the liquid to be treated with ultraviolet rays emitted from a discharge lamp which co-emits ultraviolet rays of 220 nm or less and 254 nm, and decomposes the organic matter of the liquid. In the liquid processing apparatus, the discharge lamp includes, as the discharge lamp, an arc tube made of synthetic quartz glass having an inner diameter of 8 mm or more, and a pair of filaments at L (cm) intervals at both ends of the arc tube. A lamp voltage V (V) at the time of lighting and a lamp current I are formed by enclosing at least a metal containing mercury.
(A), the inter-filament distance L (cm), and the inner diameter D (mm) of the discharge path have the following relational expressions, and a discharge lamp in which a thin film of metal oxide is formed on the inner surface of the arc tube is used. A liquid processing apparatus characterized by the above. (V-Vf) / L = X / (√D · √I) and 2.6
≤ X ≤ 4.2. However, Vf is a constant factor that depends on the lighting power source, and is 1 kHz.
When it is turned on by a high frequency power source of Z or higher, Vf = 10,
When the power is turned on with a power source of less than 1 kHz, Vf = 50. Although details will be described later, by setting conditions as in the above relational expression, ultraviolet rays in a short wavelength range of 220 nm or less can be efficiently radiated, and metal oxides on the inner surface of the arc tube of such a high-performance discharge lamp can be formed. By forming a thin film,
The effect of suppressing the decrease in the illuminance of ultraviolet rays of 254 nm is further exerted.

In a preferred embodiment of the present invention, the metal oxide thin film formed on the inner surface of the arc tube of the discharge lamp is at least a metal selected from aluminum, silicon, calcium, magnesium, yttrium, zirconium and hafnium. The main component is one or more kinds of oxides. Since these metal oxides have excellent heat resistance and are chemically stable, they effectively act to prevent the adsorption of mercury oxide on the inner surface of the arc tube.

Further, the liquid treatment method using ultraviolet rays according to the present invention irradiates the liquid to be treated with ultraviolet rays by using a discharge lamp having a metal oxide thin film formed on the inner surface of the arc tube as described above. It is characterized in that the liquid is decomposed into organic matter.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a discharge lamp used in the liquid processing apparatus and method according to the present invention. First, the basic structure of the discharge lamp 31 will be described. The discharge lamp 31 has a thickness of 220 nm or less, for example, 185 nm.
And a pair of filaments 21a and 21b arranged at both ends inside the arc tube bulb 11, and the arc tube. It includes seal portions 2a and 2b and cap portions 3a and 3b provided at both ends of the valve 11. The arc tube bulb 11 has, for example, an inner diameter of 13 mm,
It is made of synthetic quartz glass having a thickness of 1 mm, and a thin film 44 of metal oxide is formed on the inner surface of the glass. Thin film 44
Is made of a material that has excellent heat resistance and is chemically stable, such as aluminum oxide. Filaments 21a, 21
In b, the distance between both filaments is 153 cm. The filaments 21a and 21b are formed by applying, for example, a barium oxide-based emitter, and the seal portion 2
It is held by inner leads 22a to 22d extending from a and 2b, respectively. The base portions 3a and 3b are made of ceramic, and one base portion 3a is provided with a pair of electric terminals 31a and 31b. Seal part 2
The molybdenum foils 24a to 24d maintain airtightness, and the inner leads 22a to 22d,
Molybdenum foils 24a to 24d, outer leads 25a,
25b and 26 through filaments 21a, 21
b has a role of electrically connecting the electric terminals 31a and 31d. The arc tube bulb 11 is filled with about 20 mg of mercury and a rare gas of about 400 Pa. In the illustrated example, the discharge lamp 31 is configured as a two-terminal type discharge lamp, as an example. That is, one end of one filament 21a is connected to one electric terminal 31a via the inner lead 22b, molybdenum foil 24b, and outer lead 25a, and the other end of the filament 21b is connected to the inner lead 22c, molybdenum foil 24c, and outer lead 25b. , 26 to the other electric terminal 31b.

As described above, the ultraviolet illuminance of the discharge lamp decreases with the passage of time, and the decrease in the ultraviolet illuminance in the wavelength range of 254 nm is caused by the reaction of oxygen generated in the tube with mercury during lighting of the discharge lamp. This is because the silver oxide thus produced is adsorbed on the inner surface of the glass and the ultraviolet transmittance of the quartz glass is lowered. This is the resonance emission of mercury at 254 nm.
This is because the ultraviolet rays in the glass self-absorb due to the presence of mercury, and when mercury oxide is adsorbed on the inner surface of the glass,
The ultraviolet transmittance at 54 nm is selectively reduced. In view of this point, the discharge lamp used in the present invention has the arc tube bulb 11
Is characterized in that a thin film 44 of a metal oxide (aluminum oxide in the present embodiment) is formed on the inner surface of the glass, and the thin film 44 prevents mercury oxide from adsorbing on the inner surface of the glass by 254 nm. It is possible to suppress a decrease in the illuminance of ultraviolet rays. It should be noted that the thin film 44 can be easily formed by applying a solution in which fine powder of aluminum oxide is suspended in butyl acetate together with a binder in advance before sealing the filament to the inner surface of the glass tube, drying and then heat-treating in an oxidizing atmosphere. Can be formed.

In carrying out the present invention, the discharge lamp 31 having the above-mentioned structure is used as an ultraviolet ray emission source in the liquid processing apparatus. The configuration of the liquid processing apparatus itself may be, for example, a closed type liquid processing apparatus as shown in FIG. 10 or an open channel type liquid processing apparatus. Further, the discharge lamp 31 used in one liquid treatment device
Is not limited to one, but may be plural.

The material of the arc tube bulb 11 of the discharge lamp 31 according to this embodiment may be fused quartz glass starting from natural quartz or silica sand, or synthetic quartz glass. First, an example in which the material of the arc tube bulb 11 is made of fused silica glass will be described. For example, the quartz glass of the arc tube bulb 11 is made of natural quartz or silica sand as a starting material, and is made of four kinds of sodium (Na), potassium (K), titanium (Ti) and iron (Fe). Total element content is 2.5p
It is made of gas fused silica glass having pm or less and 10 ppm or more of OH groups. In this way, the discharge lamp 3
In the quartz glass constituting the material of the arc tube bulb 1 of No. 1, the discharge lamp 31 is made to contain OH groups on sodium (Na), potassium (K), titanium (Ti) and iron (Fe). The deterioration with time of the quartz glass of the arc tube bulb 11 due to the ultraviolet rays in the short wavelength range emitted by can be considerably improved.

FIG. 2 shows the composition of quartz glass such as sodium (Na), potassium (K), titanium (Ti),
3 is an ultraviolet intensity maintenance rate curve obtained by performing lighting experiments on various discharge lamps manufactured using the total content of iron (Fe) and the content of OH groups as parameters.
The shape and dimensions of the discharge lamp are the same, the horizontal axis represents the lighting time, and the vertical axis represents the initial value of the intensity of the discharge lamp according to the present invention.
It is the ultraviolet intensity of 185 nm wavelength when 0% is set. The composition conditions of the quartz glass in each discharge lamp corresponding to each curve A, B, C, D are as shown in the table below.

[Table 1] Curve Total content of Na, K, Ti, Fe Amount of OH group A 2.5ppm or less 100ppm B 4.2ppm 100ppm C 4.5ppm less than 10ppm D 6.4ppm less than 10ppm

The curve A shows that the total content of the elements consisting of four kinds of sodium (Na), potassium (K), titanium (Ti) and iron (Fe) defined in this embodiment is 2.5 p.
The condition is that it is pm or less and contains 10 ppm or more of OH groups, and the curves B, C, and D do not satisfy this condition. In FIG. 2, as is clear from the curve A showing the best results, the four impurities of sodium (Na), potassium (K), titanium (Ti), and iron (Fe) in the quartz glass were observed. By setting the total content of the elements of the species and the content of the OH group according to the present invention, it is possible to greatly improve the ultraviolet illuminance maintenance factor in the short wavelength region over time. In addition, in the experiment of FIG. 2, ozone is generated by a reaction to ultraviolet rays in the atmosphere, and if the generated ozone intervenes between the discharge lamp and the ultraviolet intensity meter, the measured value varies, so the ultraviolet intensity meter is used for the discharge lamp. It was directly attached to the outer surface and measured.

In the technical field such as organic substance decomposition treatment using ultraviolet rays to which the present invention is applied, the ultraviolet ray maintenance rate after one year of use is generally regarded as 70% regardless of the input density of the discharge lamp. From that point of view, the quartz glass having the composition that gives the result of the curve A in FIG. 2 is effective, and the quartz glass having the composition giving the results of the curves B, C, and D is obviously not effective. I know there isn't. In this way, sodium (N
a), potassium (K), titanium (Ti), iron (F)
If the total content of the four elements of e) is "2.5 ppm or less", it is possible to secure the ultraviolet maintenance factor of 70% or more after one year of use. Note that if the content of the OH group is remarked, less than 10 ppm is insufficient for the recombination effect of Si-OH.

The quartz glass made of the above materials is
It is not limited to the arc tube bulb of the discharge lamp itself, but can be used in any part, part, or device that is used by being exposed to ultraviolet rays in the wavelength range of 220 nm or less. For example, the quartz glass according to the present invention can be used as the material of the ultraviolet-transparent glass wall in the outer tube (protective tube) 20 as shown in FIG. The shape of the outer tube (protection tube) for accommodating the discharge lamp, that is, the container is not limited to the cylindrical shape, and may be any shape. Of course, the type of fused silica glass that constitutes the arc tube bulb 11 of the discharge lamp 31 according to the present embodiment is not limited to the above-mentioned gas fusion type, but may be, for example, an electric fusion type.

Further, in another embodiment of the discharge lamp 31 according to the present embodiment, the arc tube bulb 11 is made of synthetic quartz glass, and in that case, a predetermined length capable of efficiently emitting an ultraviolet ray having a wavelength of 185 nm. It is characterized in that the dimensions of the discharge lamp 31 (various sizes such as the inner diameter of the bulb and the distance between filaments) are determined under the above condition. As will be described later in detail, this makes it possible to increase the illuminance maintenance rate of short-wavelength ultraviolet rays of the discharge lamp and improve the irradiation efficiency of short-wavelength ultraviolet rays. Such a high-performance discharge lamp that suppresses a decrease in the illuminance of 254 nm ultraviolet light is
When used in an ultraviolet irradiation device for liquid processing, it is extremely significant because it can improve the processing capacity and dramatically increase the life of the device.

When the arc tube bulb 11 is made of synthetic quartz glass, an example of setting conditions of the dimensions of the discharge lamp 31 (various sizes such as the bulb inner diameter and the distance between filaments) will be described. Discharge lamp 31 according to the present embodiment
Is the inner diameter D of the arc tube bulb 11 made of synthetic quartz glass so that it can efficiently emit ultraviolet light having a wavelength of 185 nm.
The size (unit is mm) is 8 mm or more, the interval between the filaments 21a and 21b is L (unit is cm), the lamp voltage during lighting is V (unit is V (volt)), and the lamp current is I (unit is A). (Ampere)), the relationship between each value is set so as to have the following relational expression. (V-Vf) / L = X / (√D · √I), where 2.
6 ≦ X ≦ 4.2 Here, Vf is an anode drop voltage, which is a factor (constant factor) uniquely determined by the lighting power source, and is 1 kHz.
It is assumed that Vf = 10 when lit by a high frequency power supply of z or more, and Vf = 50 when lit by a power supply of less than 1 kHz.

Next, the grounds for deriving the above relational expression as conditions for making it possible to efficiently emit ultraviolet rays having a wavelength of 185 nm will be described. The present inventors prepared a plurality of discharge lamps of various sizes, each of which has a basic structure similar to the discharge lamp 31 shown in FIG. 1, and conducted various experiments on these discharge lamps to find out the electrical characteristics of the discharge lamp and the 185 nm ultraviolet intensity. The relationship was evaluated. Specifically, the size of each discharge lamp used in this experiment was 8 mm, 13 mm, 18 mm, and 23 mm in inner diameter.
mm for each pipe diameter, wall thickness 1 mm, pipe length 100-1
A synthetic quartz glass tube of 60 cm is used, and the inter-filament distance L (cm) is set to 95 to 153 cm. In the experiment, a discharge lamp to be tested was inserted into a T-shaped glass tube with a branch tube for measuring the intensity of 185 nm ultraviolet light in the central part, the inside of the glass tube was filled with a nitrogen atmosphere, and cooling water was provided outside. Shed. Also,
The lighting power source is an electronic ballast (ballast) of about 40 kHz.
And commercial frequency electromagnetic ballast (ballast) are prepared, and the lamp current during lighting is 0.4 A, 0.6 A, and 0.0.
There were 5 grades of 8 A, 1.0 A and 1.4 A (ampere). An ultraviolet illuminance meter UV-185 (trade name) manufactured by Oak Manufacturing Co., Ltd. was used for measuring the 185 nm ultraviolet intensity.

Under the above-mentioned conditions, while keeping the current substantially constant, while changing the temperature of the cooling water, various electrical characteristics, that is, the lamp voltage V, the lamp current I, the lamp power, and 185n
m UV intensity was measured. The reason for changing the temperature of the cooling water is to change the mercury vapor pressure. That is, 1
This is because the radiation efficiency and electric characteristics of the 85 nm ultraviolet ray are considered to depend on the mercury vapor pressure, so that the relationship is clarified. By changing the temperature of the cooling water, the temperature of the coldest part where the excess mercury stays is changed, and the vapor pressure of mercury is changed. Incidentally, since the lamp voltage V depends on the mercury vapor pressure in the lamp, that is, the amount of evaporation, the lamp voltage V is variably set by changing the temperature of the coldest part. In a discharge lamp of a certain physical size, the lamp current I is also a constant factor determined by the ballast, so the factor that can influence the 185 nm ultraviolet intensity is mainly the lamp voltage V. Therefore, the value of the lamp voltage V is variously changed by changing the temperature of the cooling water, the value of the lamp voltage V is measured, and the
By measuring the 85 nm UV intensity, the correlation between the 185 nm UV intensity and the lamp voltage V is found under the condition of the physical size and the predetermined lamp current I. Therefore, the measurement is performed in that manner.

On the basis of this measurement result, for the 185 nm UV intensity, from the viewpoint of "UV intensity per power consumption", the measured 185 nm UV intensity value is divided by the measured lamp power, and the quotient is "radiated". It was used as an index of "efficiency" (that is, "185 nm ultraviolet radiation efficiency"). Regarding the lamp voltage, from the viewpoint of "voltage per unit length", the value V of the measured lamp voltage
Fixed value Vf from (V) to anode drop voltage (Vf)
(V) was subtracted, the solution "V-Vf" was divided by the inter-filament distance L, and the quotient was defined as "potential gradient" (that is, the lamp voltage per unit length of the inter-filament distance). That is, by converting the measured “185 nm UV intensity” and “lamp voltage V” into “185 nm UV radiation efficiency” and “potential gradient” (lamp voltage per unit length of filament distance), The value of “185 nm ultraviolet radiation efficiency” can be compared with each value of “potential gradient”, and it is possible to grasp where the conditions of good radiation efficiency are. As described above, the anode drop voltage Vf is set to Vf = 10 when lit by a high frequency power supply of 1 kHz or higher, and Vf = 50 when lit by a power supply of less than 1 kHz.

FIG. 3 shows, as an example, a discharge lamp using a synthetic quartz glass tube having a wall thickness of 1 mm has an inner diameter of 13 m.
m, tube length 154 cm, distance between filaments 147 cm under physical conditions, the electrical condition is a lamp current I of 1
It shows the measurement results of "potential gradient" and "185 nm ultraviolet radiation efficiency" in the case of using an electronic ballast of about 40 kHz at A (ampere) (that is, Vf = 10). The horizontal axis represents the value of "185 nm ultraviolet radiation efficiency" corresponding to the horizontal axis, and the vertical axis represents the measurement results. The lamp voltage V was changed by changing the temperature of the cooling water as described above.
According to FIG. 2, the “potential gradient” is about 0.88 (V / cm)
It can be seen that at the time of, "185 nm ultraviolet radiation efficiency" shows the highest value (about "6"). From here, we can see
As long as the physical and electrical conditions are set so that the “185 nm ultraviolet radiation efficiency” falls within an appropriate allowable range including the maximum value, that is, the peak value (about “6” in the example of FIG. 2), That is, it is possible to provide a discharge lamp and an ultraviolet irradiation device that can efficiently emit 185 nm ultraviolet light. As for this allowable range, it was found by observing the actual ultraviolet irradiation state that it is appropriate to include about 60 to 70% of the peak value of "185 nm ultraviolet radiation efficiency" within the allowable range. For example, in the example of FIG. 3, if the value of “185 nm ultraviolet radiation efficiency” is at least about 3.6 or more, it can be considered that efficient radiation is obtained. In that case, the "potential gradient" is about 0.72-1.
It can be seen from the figure that the various conditions may be set so that they fall within the range of about 16.

Another measurement result will be described. Figure 3
In a discharge lamp having a tube diameter of 13 mm, a tube length of 154 cm, and a filament-to-filament distance of 147 cm, the lamp current I is varied to be "1" at each lamp current value.
The optimum potential gradient at which the “85 nm ultraviolet radiation efficiency” has a peak value was searched for. FIG. 4 is a diagram in which the optimum “potential gradient” (horizontal axis) at each lamp current value (vertical axis) obtained as a result is plotted. From this Figure 4, the optimum "potential gradient"
Is almost inversely proportional to the square root (√I) of the lamp current value (I).

In the same manner, the optimum "potential gradient" at which the "185 nm ultraviolet radiation efficiency" reaches the peak value was searched for the discharge lamps of all sizes used in the present experiment. It has been found that the optimum "potential gradient" is almost inversely proportional to the square root (√I) of the current value (I). Further, as a result of plotting the optimum “potential gradient” using the tube diameter (D) as a parameter, it was found that, as shown in FIG. 5, it is almost inversely proportional to the square root (√D) of the tube diameter (D) at any current. did. That is, the inner diameter (D) is 8 to 23 m
In a discharge lamp of m, when the lamp current is operated in the range of 0.4 to 1.4 A, the optimum "potential gradient" for obtaining the maximum radiation efficiency of 185 nm is the tube diameter (D) and the current ( It was found to be inversely proportional to the square root of I) (√D and √I). This results in inclusion of both high frequency electronic ballasts and commercial frequency electromagnetic ballasts, as long as the factor of the lighting current is taken into consideration.

From the above, in the optimum "potential gradient", the "potential gradient", that is, "(V-Vf) / L", is the square root of the tube diameter D (√D) and the square root of the lamp current I (√ I)
Is inversely proportional to, and if the proportional constant is X,
It can be expressed by the following relational expression. (V-Vf) / L = X / (√D · √I) In the case of the example of FIG. 3, the inner diameter D = 13 mm, the lamp current I
Since = 1 A, (√D · √I) is about 3.605, and in order for the “potential gradient” to fall within the allowable range of about 0.72 to 1.16 described above, the proportional constant X Should have a value in the range of approximately “2.6 ≦ X ≦ 4.2”.

Considering the above experimental results, the arc tube bulb 11 made of synthetic quartz glass as shown in FIG.
In the discharge lamp 31 using, the inner diameter D (unit: mm) of the arc tube bulb 11 made of synthetic quartz glass is 8
mm or more, and the distance between the filaments 21a and 21b is L
(Unit is cm), the lamp voltage at lighting is V (unit is V
(Volts)), and the lamp current is I (unit is A (ampere)), it is necessary to set the relation of each value to have the following relational expression, which is a condition for efficient emission of 185 nm ultraviolet rays. It was concluded that it is better to do it. (V-Vf) / L = X / (√D · √I), where 2.
6 ≦ X ≦ 4.2 Here, as described above, the anode drop voltage Vf, which is a factor uniquely determined by the lighting power supply, is Vf = 10 and 1 kHz when lighting with a high frequency power supply of 1 kHz or higher.
It is assumed that Vf = 50 when the light source is turned on by a power source less than z.

Thus, the discharge lamp 3 according to the above embodiment
1 is, based on the above conditions, as an example, the inner diameter of the arc tube bulb is 13 mm and the distance between the filaments is 153 cm, and the material of the arc tube bulb 11 is made of synthetic quartz glass, and as shown in FIG. A thin film 44 of a metal oxide (aluminum oxide as an example in this embodiment) is formed on the inner surface of the bulb 11.

Next, the measurement result of the ultraviolet illuminance maintenance factor obtained by the lighting experiment of the discharge lamp 31 for a long period of time will be described with reference to FIG. In the figure, the horizontal axis represents the lighting time, and the vertical axis represents 1 as the initial value of the illuminance of the discharge lamp according to the present invention.
It is the ultraviolet illuminance of 185 nm and 254 nm wavelength when it is set to 00%. As a result of applying the thin film 44 on the inner surface of the arc tube bulb 11, almost no decrease in the ultraviolet illuminance in the wavelength region of 254 nm is seen, and compared with the conventional discharge lamp shown in FIG.
It can be seen that the illuminance maintenance rate has improved dramatically. Also, 1
It can be seen that the UV illuminance maintenance rate in the wavelength range of 85 nm is also significantly improved.

The liquid treating apparatus using ultraviolet rays, that is, the ultraviolet ray irradiating apparatus according to the present invention is used, for example, for refining ultrapure water used in a semiconductor manufacturing process, and in that case, long-term continuous operation for 1 to 3 years. Must withstand. If the discharge lamp according to the present invention is used, TOC (Total
(1) Organic Carbon: Total organic carbon) It is possible to achieve a synergistic effect of improving the decomposition treatment capacity and reducing the burden on the ion exchange resin. Therefore, the present invention is most suitable for the ultrapure water purification process used in the semiconductor manufacturing process and the like. Of course, the liquid treatment apparatus using ultraviolet rays according to the present invention is not limited to the semiconductor manufacturing process, and is generally used for liquid treatment for decomposition treatment, sterilization, disinfection, etc. of organic substances such as beverage production, food production, medical treatment, water treatment, etc. It is available in the field. FIG. 7 shows the unit of treatment capacity for the raw water having a TOC concentration of 10 ppb to be 1 ppb or less for the UV irradiating device B equipped with a discharge lamp according to the related art and the UV irradiating device A equipped with the discharge lamp described in the embodiment of the present invention. It is a figure which shows the measured data compared with the flow volume per power consumption. In the figure, the initial value of the conventional device B is displayed as 100%. It can be seen that the conventional device B and the device A of the present invention have a large performance difference in the initial stage, and the performance difference further increases as the usage time advances. The improvement of the TOC processing ability is due to the improvement of the ultraviolet radiation efficiency of 185 nm and the maintenance rate. However, as described above, the excessive amount of the ultraviolet rays in the short wavelength region produces an excessive peroxide, which causes the ion exchange resin It will cause deterioration of life,
By using the discharge lamp according to the present invention, it is possible to reduce the burden on the ion exchange resin by suppressing the decrease in the illuminance of ultraviolet rays of 254 nm.

FIG. 8 shows an ultraviolet irradiation device B according to the prior art.
And the specific resistance value of the treated water in the ultraviolet irradiation device A using the discharge lamp described in the examples of the present invention, is the result of measurement at the outlet of the ion exchange resin process in the subsequent stage. In the figure,
The vertical axis represents the specific resistance value, and the horizontal axis represents the lighting time. The specific resistance value depends on the concentration of peroxide, and the higher the concentration of peroxide, the lower the specific resistance value. That is, when the leakage of peroxide increases due to the deterioration of the ion exchange resin, the specific resistance value decreases, so that the transition of the specific resistance value at the outlet of the ion exchange resin becomes a level indicator of the deterioration of the ion exchange resin. The specific resistance value at the initial stage of use of the apparatus was a little over 18 MΩ in both the conventional apparatus B and the apparatus A of the present invention. However, one year after the start of using the apparatus, the specific resistance value of the conventional apparatus B was ion exchanged. It decreased to about 16 MΩ, which is a standard for resin renewal. On the other hand, in the device A of the present invention, the decrease in the specific resistance value after the lapse of the use period is extremely small, and it can be seen that the load on the ion exchange resin is reduced. This is 254
By the dramatic improvement of the UV illuminance maintenance rate in the wavelength range of nm,
This is because the peroxide treatment capacity is maintained.

As described above, the present invention is 220 nm.
In a discharge lamp that co-emits the following short-wavelength region and 254 nm ultraviolet light, a thin film of a metal oxide is formed on the inner surface of the arc tube to increase the 254 nm ultraviolet illuminance maintenance rate, and to be treated by the ultraviolet light from the discharge lamp. This is an invention in which decomposition of an unintended intermediate product is promoted by performing a treatment such as decomposition of an organic substance in a liquid. In the above-mentioned embodiment, the discharge lamp was described in which the arc tube was made of synthetic quartz glass, and the dimensions were determined under predetermined conditions so that the ultraviolet rays having a wavelength of 185 nm could be efficiently emitted. However, in this case, the action is particularly great. Although the effects can be obtained, the embodiment of the present invention is not limited to this. For example, the same effects can be obtained even when a normal (natural) quartz glass is used as a material for the arc tube. . Further, the metal oxide used as the thin film formed on the inner surface of the glass of the discharge lamp has been described as an example using aluminum oxide, but not limited to this, aluminum, silicon, calcium, magnesium, yttrium, zirconium and hafnium It is effective if the main component is at least one oxide of a metal selected from the above. The form of the discharge lamp is a discharge lamp of a type in which mercury and an amalgam of another metal are enclosed, as long as it is a discharge lamp that co-emits a wavelength range of 220 nm or less and ultraviolet rays of 254 nm, a continuous filament heating The present invention can be applied to any form such as a heating type or a type in which a filament and an anode are provided side by side, and similar effects can be obtained.

[0037]

As described above, according to the present invention, 220n
In the discharge lamp that co-emits a wavelength range of m or less and 254 nm of ultraviolet light, the UV irradiation maintenance factor of 254 nm is remarkably increased, and at the same time, the radiation efficiency of ultraviolet rays of 220 nm or less is improved and the irradiation maintenance factor is increased, thereby improving the discharge lamp. In the liquid processing apparatus and method using, it is possible to achieve a long service life of each equipment and energy saving and maintenance effects.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment of a discharge lamp used in a liquid treatment apparatus using ultraviolet rays according to the present invention.

FIG. 2 shows sodium (N
The graph which shows the ultraviolet intensity maintenance rate curve obtained by carrying out the lighting experiment of various discharge lamps manufactured as a), potassium (K), and Ta for a long period of time. The total content of titanium (Ti) and iron (Fe) and the content of OH groups were set as parameters.

FIG. 3 is a graph exemplifying a relationship between “potential gradient” and “185 nm ultraviolet radiation efficiency” based on an experimental result according to an example of a discharge lamp used in the present invention.

FIG. 4 is a graph illustrating a relationship between a “lamp current” and an optimum “potential gradient” based on an experimental result according to an embodiment of a discharge lamp used in the present invention.

FIG. 5 is a graph exemplifying the relationship between the inner diameter of the glass tube and the optimum “potential gradient” based on the experimental results according to an example of the discharge lamp used in the present invention, corresponding to each value of “lamp current”. .

FIG. 6 shows the discharge lamps used in the present invention at 185 nm and 25 nm.
The graph which shows an example of a 4 nm ultraviolet irradiation maintenance rate.

FIG. 7 is a graph illustrating an experimental result of a change in TOC decomposition treatment capacity with time in a liquid treatment apparatus according to the present invention, that is, an ultraviolet irradiation apparatus, as compared with a conventional apparatus.

FIG. 8 is a graph exemplifying a transition of the specific resistance value at the ion-exchange resin outlet with time in the liquid processing apparatus according to the present invention, that is, the ultraviolet irradiation apparatus, as compared with the conventional apparatus.

FIG. 9: 185 nm and 25 in a prior art discharge lamp
The graph which shows an example of a 4 nm ultraviolet irradiation maintenance rate.

FIG. 10 is a schematic side sectional view showing an example of an ultraviolet irradiation apparatus using a conventional discharge lamp.

[Explanation of symbols]

31 discharge lamp 11 arc tube bulb 21a, 21b filament 2a, 2b Seal part 3a, 3b base part 22a to 22d inner lead 31a, 31b electrical terminals

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01J 61/72 H01J 61/72

Claims (7)

[Claims] 1. A liquid processing apparatus for irradiating a liquid to be treated with ultraviolet rays radiated from a discharge lamp which co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays to decompose organic matter of the liquid, and the like. A liquid treatment apparatus comprising: a discharge lamp having a metal oxide thin film formed on the inner surface of the arc tube. 2. A liquid processing apparatus for irradiating a liquid to be treated with ultraviolet rays emitted from a discharge lamp that co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays to decompose organic matter of the liquid, and the like. The discharge tube of the discharge lamp uses natural quartz or silica sand as a starting material, and the total content of elements consisting of four kinds of sodium, potassium, titanium and iron is 2.
A liquid treatment apparatus comprising a discharge lamp made of quartz glass having an OH group content of 5 ppm or less and 10 ppm or more and having a thin film of a metal oxide formed on the inner surface of the arc tube. 3. A liquid processing apparatus for irradiating a liquid to be treated with ultraviolet rays radiated from a discharge lamp that co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays to decompose organic matter of the liquid, and the like. An arc tube made of synthetic quartz glass having an inner diameter of 8 mm or more, and a pair of filaments at intervals of L (cm) at both ends of the arc tube, in which a rare gas and a metal containing at least mercury are enclosed. , The lamp voltage V (V) during lighting, the lamp current I (A), the inter-filament distance L (cm), and the inner diameter D (mm) of the discharge path have the following relational expressions and A liquid processing apparatus comprising a discharge lamp formed by forming a thin film of metal oxide. (V-Vf) / L = X / (√D · √I) and 2.6
≤ X ≤ 4.2. However, Vf is a constant factor that depends on the lighting power source, and is 1 kHz.
When it is turned on by a high frequency power source of Z or higher, Vf = 10,
When the power is turned on with a power source of less than 1 kHz, Vf = 50. 4. The thin film of metal oxide formed on the inner surface of the arc tube of the discharge lamp is an oxide of at least one metal selected from aluminum, silicon, calcium, magnesium, yttrium, zirconium and hafnium. The liquid treatment apparatus according to claim 1, wherein the liquid treatment apparatus is mainly composed of. 5. A liquid treatment method of irradiating a liquid to be treated with ultraviolet rays radiated from a discharge lamp that co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays to decompose organic matter of the liquid, and the like. A liquid treatment method comprising using a discharge lamp having a metal oxide thin film formed on the inner surface of the arc tube. 6. A liquid treatment method for irradiating a liquid to be treated with ultraviolet rays radiated from a discharge lamp that co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays to decompose organic matter of the liquid, and the like. The discharge tube of the discharge lamp uses natural quartz or silica sand as a starting material, and the total content of elements consisting of four kinds of sodium, potassium, titanium and iron is 2.
A liquid treatment method comprising using a discharge lamp comprising silica glass containing 5 ppm or less and 10 ppm or more of OH groups, and forming a metal oxide thin film on the inner surface of the arc tube. 7. A liquid treatment method of irradiating a liquid to be treated with ultraviolet rays radiated from a discharge lamp that co-emits ultraviolet rays of 220 nm or less and 254 nm ultraviolet rays, and subjecting the liquid to organic substance decomposition treatment, wherein the discharge lamp is An arc tube made of synthetic quartz glass having an inner diameter of 8 mm or more, and a pair of filaments at intervals of L (cm) at both ends of the arc tube, in which a rare gas and a metal containing at least mercury are enclosed. , The lamp voltage V (V) during lighting, the lamp current I (A), the inter-filament distance L (cm), and the inner diameter D (mm) of the discharge path have the following relational expressions and A liquid treatment method comprising using a discharge lamp formed by forming a thin film of a metal oxide. (V-Vf) / L = X / (√D · √I) and 2.6
≤ X ≤ 4.2. However, Vf is a constant factor that depends on the lighting power source, and is 1 kHz.
When it is turned on by a high frequency power source of Z or higher, Vf = 10,
When the power is turned on with a power source of less than 1 kHz, Vf = 50.