JP4258355B2 - Decomposition treatment equipment for ethylene oxide - Google Patents

Description

  The present invention is directed to exhaust gas containing ethylene oxide discharged from an ethylene oxide sterilization apparatus used for sterilization of medical devices, and enables ethylene oxide in the exhaust gas to be efficiently decomposed.

  In exhaust gas discharged from a sterilizer using ethylene oxide after sterilization, the concentration of ethylene oxide is high because the gas in the device is sucked without introducing outside air into the sterilizer at the beginning of the discharge. In particular, in a sterilizer using a cartridge-type cylinder as an ethylene oxide source, the ethylene oxide concentration in the exhaust gas is almost 100%. And as exhaust gas discharge from the sterilizer proceeds, the ethylene oxide concentration in the exhaust gas rapidly decreases.

  Furthermore, in order to remove ethylene oxide adhering to and adsorbing to the material to be sterilized such as gauze in the sterilizer, outside air is introduced into the sterilizer, and after a while, the gas in the apparatus is sucked again. An operation of repeating the process several times is performed, and the ethylene oxide concentration in the exhaust gas discharged during this cleaning process also varies.

In such a method of decomposing ethylene oxide in exhaust gas having a large variation in ethylene oxide concentration using a conventional oxidation catalyst, the treatment capacity of the oxidation catalyst must be made to correspond to the highest concentration of ethylene oxide in the exhaust gas. In other words, there is a drawback that the cost of the decomposition treatment apparatus increases, such as a large amount of oxidation catalyst that must be used.
For this reason, as disclosed in WO99 / 61137, a method has been proposed in which the fluctuation of the ethylene oxide concentration in the exhaust gas is reduced and the ethylene oxide concentration is lowered before being sent to the decomposition treatment apparatus.

In this prior invention, as shown in FIG. 6, exhaust gas from a sterilizer (not shown) is introduced into a container 1 for storing a liquid such as water via a pipe 2 and a valve 3, and the liquid is supplied from the aeration member 4 to the liquid. The exhaust gas is aerated and the ethylene oxide in the exhaust gas is dissolved in the liquid and absorbed. The exhaust gas in which most of the ethylene oxide in the exhaust gas is absorbed and the ethylene oxide concentration is greatly reduced is sent from the container 1 through the pipe 5 to the catalytic combustion apparatus 6 filled with the oxidation catalyst, where it is decomposed.
When the ethylene oxide concentration in the exhaust gas supplied from the sterilizer decreases, the air pump 7 is operated to send the outside air into the pipe 2, and the outside air is aerated into the liquid in the container 1 to enter the liquid. The dissolved ethylene oxide is transferred into the air. The air from which the ethylene oxide is eluted is sent to the catalytic combustion device 6 for decomposition treatment.

  In this decomposition treatment method, the large fluctuation range of the ethylene oxide concentration in the exhaust gas is reduced and leveled, and the ethylene oxide concentration becomes low. Therefore, exhaust gas containing a high concentration of ethylene oxide may be sent to the catalytic combustion apparatus 6. In other words, the catalytic combustion apparatus 6 can be reduced in size, and the equipment cost can be reduced.

However, the ethylene oxide decomposition treatment method of the prior invention has the following problems.
First, since an oxidation catalyst is used as a means for decomposing ethylene oxide, the exhaust gas after decomposition becomes high temperature (300 to 400 ° C.) and cannot be discharged as it is. Must be provided.
Further, when the concentration of ethylene oxide in the exhaust gas from the container 1 is not sufficiently reduced for some reason and exhaust gas containing ethylene oxide at a concentration exceeding the treatment capacity of the oxidation catalyst is sent to the catalytic combustion apparatus 6 Undecomposed ethylene oxide may be discharged out of the system.
Furthermore, since the air pump 7 is operated, the entire decomposition treatment apparatus becomes a positive pressure, and exhaust gas may leak from the apparatus to the outside. In order to prevent this, it is necessary to provide a highly confidential apparatus structure. In addition, extra equipment costs are required.
International Publication Number WO99 / 61137

  Therefore, the problem in the present invention is that the exhaust gas after the decomposition treatment does not become high temperature, and even if an exhaust gas containing a high concentration of ethylene oxide flows into the decomposition treatment means for some reason, the undecomposed ethylene oxide is outside the system. An object of the present invention is to obtain an ethylene oxide decomposition treatment apparatus that is not discharged into the atmosphere. In addition, an ethylene oxide decomposition apparatus in which exhaust gas containing ethylene oxide does not leak outside from the apparatus may be obtained.

To solve this problem,
The invention according to claim 1
It introduces exhaust gas containing ethylene oxide has a buffer unit for reducing the ethylene oxide concentration in the exhaust gas, and a decomposing unit for decomposing the ethylene oxide in the exhaust gas from the buffer unit, the decomposition unit, Photocatalyst member in which titanium oxide powder having ethylene oxide resolution or titanium oxide powder compression-molded is supported on a carrier made of titanium oxide, or titanium oxide powder or titanium oxide powder that has been compression-molded is a resin binder An ethylene oxide decomposition treatment apparatus comprising a photocatalyst device having a photocatalyst member fixed to a substrate made of titanium oxide.

The invention according to claim 2, wherein the buffer unit includes a water tank filled with water, according to claim 1, characterized in that the aeration tank provided with a diffusion pipe for aeration of ethylene oxide to water in the water tank This is an ethylene oxide decomposition treatment apparatus.

The invention according to claim 3 is characterized in that an exhaust device having a negative pressure in the buffer part and the decomposition part is provided after the decomposition part. It is a decomposition processing device.
The invention according to claim 4 is the ethylene oxide decomposition treatment apparatus according to claim 2 or 3, wherein two or more aeration tanks are provided in series.
According to a fifth aspect of the present invention, a water treatment unit including a photocatalyst member is connected to the decomposition treatment apparatus according to any one of the first to fourth aspects, and water in a water tank forming the buffer unit is supplied to the decomposition treatment apparatus. An ethylene oxide decomposition treatment apparatus characterized in that it is sent to a water treatment section to decompose ethylene oxide dissolved in water.
In the present invention, the above-described decomposition treatment apparatus may be connected to an ethylene oxide sterilization apparatus to decompose ethylene oxide in exhaust gas from the ethylene oxide sterilization apparatus.

In the present invention, since the photocatalyst is employed as the ethylene oxide decomposition treatment means, the temperature of the exhaust gas after the ethylene oxide decomposition treatment is low and can be discharged as it is. In addition, since the decomposition process using the photocatalyst is performed, the processing efficiency is high, and complicated processing such as circulation processing is not required.
In addition, since the photocatalyst has the ability to adsorb ethylene oxide, even if exhaust gas containing a high concentration of ethylene oxide flows into the photocatalyst , it is once adsorbed to the photocatalyst and then gradually decomposed, so there is no decomposition. Of ethylene oxide is not discharged, and it is possible to cope with those having a small decomposition ability in the decomposition section.

In addition, when the entire decomposition treatment apparatus has a negative pressure by the exhaust part, exhaust gas containing ethylene oxide does not leak to the outside from the apparatus. Furthermore, what provided the water treatment part can decompose | disassemble the ethylene oxide melt | dissolved in the water of the water tank which makes a buffer part, and can always manage as the water which the ethylene oxide does not melt | dissolve.
Furthermore, in the case where the decomposition treatment apparatus is connected to the ethylene oxide sterilization apparatus, the ethylene oxide in the exhaust gas discharged from the ethylene oxide sterilization apparatus can be efficiently decomposed, and even if the ethylene oxide concentration in the exhaust gas varies significantly. Can handle this completely. For this reason, the exhaust gas from various kinds of ethylene oxide sterilizers can be treated.

FIG. 1 shows an example of a decomposition treatment apparatus according to the present invention. In this example, the decomposition apparatus is connected to an ethylene oxide sterilization apparatus.
In the figure, reference numeral 11 indicates an ethylene oxide sterilization apparatus, and reference numeral 51 indicates a decomposition processing apparatus. The decomposition processing unit 51 is roughly configured by a buffer unit 21, a decomposition unit 31, and an exhaust unit 41.

The ethylene oxide sterilizer 11 includes a sterilization chamber 12 and an ejector 13. The sterilization chamber 12 accommodates members to be sterilized such as various medical instruments such as a syringe, and gaseous ethylene oxide supplied from an ethylene oxide supply source 14 such as a cartridge type cylinder provided separately is introduced. Thus, the internal member to be sterilized is sterilized. A tube 15 opened to the outside air is connected to the sterilization chamber 12 via a valve 16 so that the outside air can be introduced from the tube 15.
The sterilization chamber 12 is provided with an ejector 13 that uses compressed air from a compressed air source (not shown). The ejector 13 has a function of discharging the exhaust gas containing ethylene oxide in the sterilization chamber 12 to the outside. Note that an evacuation unit such as a vacuum pump may be used instead of the ejector 13.

The buffer unit 21 of the decomposition treatment apparatus 51 is formed by connecting a first aeration tank 22A and a second aeration tank 22B in series, and each of the aeration tanks 22A and 22B is filled with water as shown in FIG. In this water tank, aeration diffusers 23A and 23B are provided so as to be submerged in water. One end of the inflow pipe 24 is connected to the diffuser pipe 23A of the first aeration tank 22A. The other end of the inflow pipe 24 can be connected to an exhaust pipe 17 for exhaust gas discharged from the ethylene oxide sterilizer 11.
A pipe 25A that opens away from the water surface is attached to the upper part of the first aeration tank 22A, and this pipe 25A is connected to the air diffusion pipe 23B of the second aeration tank 22B. A pipe 25B that opens away from the water surface is attached to the upper part of the second aeration tank 22B, and this pipe 25B is connected to the decomposition section 31.
As a result, the exhaust gas flowing from the ethylene oxide sterilizer 11 through the inflow pipe 24 receives the first aeration in the first aeration tank 22A and then the second aeration in the second aeration tank 22B, and then the decomposition unit 31. To be sent to.

In addition, a pipe 26 that is open to the outside air is connected to the inflow pipe 24 via a valve 27. By opening the valve 27, the outside air passes from the pipe 26 through the inflow pipe 24 to the water from the diffuser pipe 23 into the water. Aerated.
The aeration by the diffusion tubes 23A and 23B and the inflow of the exhaust gas from the tube 25B to the decomposition unit 31 in the buffer unit 21 are caused in the aeration tanks 22A and 22B and the decomposition unit 31 caused by the exhaust by the exhaust unit 41. It is made by negative pressure.

A decomposition unit 31 is provided at the subsequent stage of the buffer unit 21. The decomposition unit 31 includes a photocatalyst device or a photocatalyst device and a plasma decomposition device, and decomposes ethylene oxide in exhaust gas supplied from the buffer unit 21 via the pipe 25 by the action of the photocatalyst or the photocatalyst and plasma. It is.
The photocatalyst device includes a photocatalyst member and a light source that irradiates the photocatalyst member with ultraviolet light or visible light. The photocatalyst member is not particularly limited, and a titanium oxide powder having an ability to adsorb ethylene oxide or a product obtained by compression-molding this titanium oxide powder in various forms, or ethylene Known materials such as titanium oxide powder having the ability to adsorb oxides or those obtained by compression-molding this titanium oxide powder are fixed to a substrate with various binders such as resins are used.
Further, as the titanium oxide powder, those having an anatase type crystal structure are mainly used, and those exhibiting a catalytic function not only by ultraviolet rays but also by irradiation with visible rays are preferable.

  Further, a material having hydrophilicity and adsorptivity can be adopted as the carrier or base material constituting the photocatalyst member, and a high adsorbability to ethylene oxide can be imparted to the photocatalyst member. Examples of materials used as a carrier or substrate having hydrophilicity and adsorptivity include zeolite, silica gel, diatomaceous earth, and titanium oxide. The shape of the photocatalyst member is preferably a tablet or a granule having a large surface area and high adsorption ability.

  The plasma decomposing apparatus is not particularly limited, and a conventionally known non-equilibrium plasma or the like is used. As a discharge form for forming this non-equilibrium plasma, pulse streamer discharge, silent discharge, partial discharge, creeping discharge, etc. are used. Among these, the creeping discharge method is preferable because generation of nitrogen oxides (NOx) is suppressed.

Furthermore, when using a photocatalyst and non-equilibrium plasma together, the decomposition efficiency becomes high by adopting the following composite form.
FIG. 3 shows a disassembling part main body as an example of this composite form, and reference numeral 32 in FIG. 3 denotes a pipe made of a transparent dielectric such as glass. A first electrode 33 is provided on the outer peripheral surface of the pipe 32, and a second electrode 34 is provided on the inner peripheral surface. These electrodes 33 and 34 are made of a light-transmissive metal thin film, a transparent conductor such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), or a mesh or spiral metal or a printed conductor. It consists of

The pipe 32 is filled with a large number of granular photocatalytic members 35, 35. Further, a light source (not shown) is provided outside the pipe 32 so that ultraviolet light and visible light from the light source pass through the pipe 32 and are irradiated to the internal photocatalyst members 35, 35. It has become.
Further, the first electrode 33 and the second electrode 34 are connected to an AC power source 36 so that an AC voltage is applied, and non-equilibrium plasma is generated in the pipe 32 by the application of the AC voltage. It is supposed to be.
Then, by flowing the exhaust gas through the pipe 32, ethylene oxide in the exhaust gas is once adsorbed by the photocatalyst members 35, 35... And gradually decomposed by the action of the photocatalyst and plasma.

  In such a composite form, the photocatalyst is excited by ultraviolet light and visible light generated by plasma emission, in addition to the photocatalyst and the original decomposition action of plasma, and the decomposition proceeds. In addition, ozone generated by the plasma increases the decomposition efficiency of the photocatalyst. Furthermore, carbon monoxide generated by the plasma is changed to carbon dioxide by the oxidizing action of the photocatalyst, and the generation rate of harmful carbon monoxide is reduced.

  An exhaust part 41 is provided after the decomposition part 31. The exhaust unit 41 sucks the decomposition treatment gas discharged from the decomposition unit 31 through the pipe 42 and discharges it to the outside, and makes the inside of the decomposition unit 31 and the buffer unit 21 in the previous stage negative pressure. is there. A normal vacuum pump, an ejector or the like is used for the exhaust part 41. The decomposition process gas discharged from the exhaust part 41 is discharged from the pipe 43 to the outside of the system. The exhaust part 41 is always in an operating state, and the inside of the constant decomposition part 31 and the buffer part 21 is set to a negative pressure.

  In addition, a water treatment unit 61 is provided. The water treatment unit 61 irradiates a water treatment unit main body formed by filling a transparent pipe such as glass with a photocatalyst such as the above-described photocatalytic member, and ultraviolet light and visible light installed outside the transparent pipe. And a light source. The water treatment unit 61 pumps the water filled in the first and second aeration tanks 22A and 22B of the buffer unit 21 to the main body of the water treatment unit, where the ethylene oxide dissolved in the water is decomposed, and the ethylene It has a function of returning water from which oxides have been removed to the first and second aeration tanks 22A and 22B.

  By providing the water treatment unit 61, the water in the first and second aeration tanks 22A and 22B forming the buffer unit 21 can be kept in a state in which ethylene oxide is not always dissolved. In addition, this water treatment part 61 does not necessarily need to be attached.

Next, a method for treating exhaust gas containing ethylene oxide discharged from the ethylene oxide sterilizer 11 using the decomposition treatment device 51 will be described.
When the sterilization process is completed in the sterilization chamber 12, first, exhaust gas having a high ethylene oxide concentration is discharged by operating the ejector 13, and this exhaust gas is sent from the pipes 17 and 24 to the buffer unit 21. Next, the valve 16 is opened, the ejector 13 is operated intermittently, outside air is introduced into the sterilization chamber 12 through the pipe 15, and adheres to the ethylene oxide remaining in the sterilization chamber 12 and the object to be sterilized. The operation (cleaning step) of separating the adsorbed ethylene oxide and sending the exhaust gas to the buffer unit 21 is performed a plurality of times.
The time change of the exhaust gas amount from the sterilizer 11 at this time is shown in FIG. In FIG. 4, the vertical axis represents the amount of exhaust gas, and the horizontal axis represents the elapsed time. Exhaust gas is discharged with a large amount of discharge during the initial tens of minutes, but after that, the intermittent cleaning process shows a large amount of discharge only for a short time, and at other times it becomes a small amount of discharge. Yes.

  At this time, if the ethylene oxide concentration of the exhaust gas discharged from the sterilizer 11 is measured as it is, this temporal change starts from a high concentration close to 100% and shows a sudden and large fluctuation. The solid line A in FIG. 5 shows this ethylene oxide concentration. Here, the vertical axis represents the ethylene oxide concentration, and the horizontal axis represents the time from the start of treatment. This variation is similar to the ethylene oxide concentration of the exhaust gas of the prior art described above, and the initial exhaust gas exhibits a high concentration close to 100% due to gas suction in the sterilizer 11 (a). As the discharge proceeds, this concentration decreases rapidly (b). Thereafter, when outside air is introduced into the sterilization chamber 12, ethylene oxide adhering to gauze or the like is released, and the concentration of ethylene oxide in the sterilization chamber 12 increases again. When the exhaust gas is sucked, the ethylene oxide concentration once lowered becomes slightly higher (c), but when it is released again, the concentration of ethylene oxide decreases again (d). As a result of repeating this, the fluctuation range of the ethylene oxide concentration becomes smaller with time, the ethylene oxide concentration becomes smaller, and becomes almost 0% in several minutes.

  In the buffer unit 21, the large fluctuation of the ethylene oxide concentration is reduced, and at least, the concentration is reduced to a concentration lower than the maximum concentration of ethylene oxide discharged from the sterilization chamber 12. Specifically, it is preferable that the ethylene oxide concentration in the exhaust gas discharged from the buffer unit 21 is 30000 ppm or less, preferably 3000 ppm or less, which is the explosion limit.

The exhaust gas from the sterilizer 11 is aerated into the water from the first and second aeration tanks 22 </ b> A and 22 </ b> B of the buffer unit 21 through the inflow pipe 24 connected to the discharge pipe 17. Ethylene oxide in the exhaust gas is soluble in water because it is water-soluble. When the concentration of ethylene oxide at the beginning of exhaust gas discharge is high, most of it is dissolved in water, and some ethylene oxide that cannot be dissolved is transferred from water to air, and this exhaust gas is reduced in ethylene oxide concentration. In this state, it is discharged from the tube 25 and sent to the disassembling unit 31.
Aeration by the first and second aeration tanks 22 </ b> A and 22 </ b> B in the buffer unit 21 is always performed by the normal operation of the exhaust unit 41.

In addition, most of the exhaust gas discharged from the sterilizer 11 in the cleaning process is air. By aeration of this exhaust gas, ethylene oxide previously dissolved in water is gasified and transferred to the air. The exhaust gas having a low ethylene oxide concentration is sent from the pipe 25B to the decomposition section 31.
As described above, in the buffer unit 21, the ethylene oxide concentration in the exhaust gas in which the concentration of ethylene oxide discharged from the sterilization unit 11 is drastically reduced is reduced to be less than the maximum concentration of ethylene oxide in the exhaust gas from the sterilization unit 11. Then, it is sent from the buffer unit 21 to the decomposition unit 31. An example of a temporal change in ethylene oxide concentration in the exhaust gas supplied from the buffer unit 21 to the decomposition unit 31 is shown by a broken line B in FIG.

  A broken line B in FIG. 5 shows a temporal change in the ethylene oxide concentration of the exhaust gas discharged from the first aeration tank 22A. This variation is the same as the variation of the ethylene oxide concentration of the exhaust gas according to the prior invention. In the first aeration tank 22A, since the ethylene oxide concentration has been lowered in advance, the ethylene oxide concentration in the first stage is much lower than the ethylene oxide concentration of the gas discharged from the sterilizer 11 (a ′). When comparing when the time has elapsed, the ethylene oxide concentration is first reversed between A and B (b ′). This is because ethylene oxide is saturated in water and discharged without being dissolved. Even if external air is intermittently introduced into the sterilization chamber 12 and ethylene oxide adhering to gauze or the like is released, there is no sensitive change in concentration because of the first aeration tank 22A. As a result, the ethylene oxide concentration approaches a constant value, but by aeration of the ethylene oxide in the first aeration tank 22A, ethylene oxide dissolved in water is gasified and discharged, so that the ethylene oxide concentration further decreases. .

The exhaust gas aerated in the first aeration tank 22A is further aerated in the second aeration tank 22B. That is, since the exhaust gas accompanied by the change indicated by the broken line B in the temporal change in the ethylene oxide concentration in the exhaust gas flowing into the second aeration tank 22B is aerated again, the ethylene oxide of the exhaust gas from the second aeration tank 22B The change with time of the density is further leveled and becomes a change as shown by a solid line C in FIG.
The ethylene oxide concentration of the exhaust gas from the second aeration tank 22B is suppressed to a very low concentration even when a large amount of exhaust gas flows into the buffer unit 21 at a high concentration in the initial stage of discharge, as shown in FIG. 5C. Thereafter, it is sent to the decomposition unit 31 at an average concentration. Further, during the operation of the buffer unit 21, especially when the sterilizer 11 is in the cleaning process, the valve 27 can be opened, outside air can be introduced from the tube 26, and this outside air can be aerated from the diffuser tube 23. By performing aeration with the outside air, the aeration can be continuously performed, and the aeration time does not change regardless of the attachment to any type of sterilization apparatus, and the processing efficiency can be kept high.

The degree of reduction of the ethylene oxide concentration in the buffer unit 21 may be set according to the subsequent decomposing ability in the decomposing unit 31, but in the present invention, the highest concentration of ethylene oxide discharged from the sterilizer 11 Less than and less than the adsorption capacity of the photocatalyst member, and the integrated value of the ethylene oxide concentration that has flowed into the decomposition section 31 during the elapsed time from the decomposition start time to the end time in the decomposition section 31 is a photocatalyst or photocatalyst and plasma. It is sufficient that the decomposition ability is controlled to be equal to or less than the integral value at the same elapsed time. Preferably, it is preferably 3% or less, which is the explosion limit of ethylene oxide.
In addition, since the two-stage aeration tanks 22A and 22B are provided, there is no loss of ethylene oxide (inflow of high-concentration ethylene oxide into the decomposition unit 31) at the time of discharging at a high flow rate and high concentration in the initial stage of processing, and the decomposition unit 31. Then, it is possible to process with the minimum decomposition capacity according to the low flow rate thereafter. In addition, a certain concentration of ethylene oxide can be fed into the decomposition unit 31.

The exhaust gas from the buffer unit 21 is sent to the decomposition unit 31 through the pipe 25B, where it is decomposed. The decomposition process in the decomposition unit 31 is performed by using a photocatalyst member having ethylene oxide adsorption ability or a combination of this photocatalyst member and a plasma decomposition apparatus.
The decomposition process of ethylene oxide by this photocatalyst member or photocatalyst member and plasma proceeds at a low temperature, and the exhaust gas after the decomposition process has a low temperature of 100 ° C. or lower. Moreover, since the ethylene oxide concentration in the exhaust gas flowing into the decomposition section 31 is low, the ethylene oxide can be completely decomposed, and undecomposed ethylene oxide is not discharged to the outside.

  In addition, since the ethylene oxide concentration in the exhaust gas flowing into the decomposition unit 31 is reduced in the buffer unit 21, the photocatalyst member can completely adsorb ethylene oxide, and the photocatalyst member gradually decomposes the ethylene oxide. To do. Adsorption here refers to physical and chemical adhesion to the surface of a substance. Therefore, undecomposed ethylene oxide is not discharged outside. In addition, as the decomposition ability of the decomposition unit 31, the ability to completely decompose ethylene oxide at that time is not essential, and if it can be completely adsorbed, ethylene oxide is temporarily adsorbed and "accumulated". Can be used even if the decomposition ability is low. In other words, even if the decomposition capacity at that time is lower than the concentration at that time, the integral value of the input concentration that has flowed in by the above-described elapsed time may be adjusted to be equal to or less than the integral value of the decomposition capacity. . That is, the adsorption rate is apparently faster than the decomposition rate. In this way, it is not necessary to deal with high-concentration ethylene oxide, it is possible to perform a decomposition process at a sufficient level with a small decomposition ability, and the entire equipment can be reduced in size and simplified.

  Moreover, the photocatalyst is originally hydrophilic and has an ability to adsorb ethylene oxide by itself. Further, when a hydrophilic or adsorptive material such as zeolite, silica gel or diatomaceous earth is used as the carrier or base material, the carrier or base material has the ability to adsorb ethylene oxide. For this reason, even if exhaust gas containing a high concentration of ethylene oxide flows from the buffer unit 21, the photocatalytic member once adsorbs the high concentration of ethylene oxide and gradually decomposes it. The decomposed ethylene oxide does not flow out to the exhaust part 41.

Next, the exhaust gas that is decomposed in the decomposition unit 31 and does not contain ethylene oxide is sucked into the exhaust unit 41 through the pipe 42 and discharged from the pipe 43 as a harmless clean gas outside the system. At this time, since the buffer unit 21 and the decomposition unit 31 are always at negative pressure by the exhaust unit 41, the exhaust gas does not leak to the outside from the buffer unit 21, the decomposition unit 31, and the pipe line.
Further, by changing the exhaust capacity in the exhaust part 41, the aeration efficiency can be increased even when the amount of ethylene oxide remaining in the water in the water tank 22 forming the buffer part 21 is small.

  The water in the first and second aeration tanks 22A and 22B forming the buffer unit 21 circulates between the water treatment unit 61, and at this time, ethylene oxide dissolved in the water is decomposed by the photocatalyst, and the ethylene oxide is It can be set as the state which is not melt | dissolving, and the ethylene oxide melt | dissolution ability of water of each aeration tank 22A, 22B does not fall.

In the present invention, as another embodiment, without using a photocatalyst for the decomposition treatment in the decomposition unit 31, it can be performed by the action of an adsorbent having an ethylene oxide adsorption ability such as zeolite, silica gel, diatomaceous earth, and plasma. .
In this case, ethylene oxide in the exhaust gas from the buffer unit 21 is once adsorbed by the adsorbent, and the ethylene oxide adsorbed on the adsorbent is gradually decomposed by the decomposition action of plasma. For this reason, in this embodiment as well, although the processing efficiency is slightly lowered, the same effect as the previous embodiment can be obtained.
As a specific form of the processing apparatus in this embodiment, an apparatus using an adsorbent such as zeolite, silica gel, diatomaceous earth or the like can be used instead of the photocatalytic member 35 in FIG.

Furthermore, as another embodiment, the aeration tank 22 in the buffer unit 21 may be a single unit depending on the ethylene oxide concentration in the exhaust gas from the sterilizer 11, the photocatalyst member, the plasma decomposition capability, and the like.
Alternatively, the exhaust part 41 may be removed, and compressed air may be sent from the pipe 26 to the buffer part 21, whereby the exhaust gas may be aerated and flow into the decomposition part 31.

A specific example is shown.
Exhaust gas (100% ethylene oxide) is aerated with water, and the ethylene oxide concentration of the exhaust gas from the buffer unit 21 is controlled to 2000 ppm. Specifically, the amount of water in the buffer unit 21 and the amount of aerated air are adjusted. This concentration can be arbitrarily set at 2000 to 4000 ppm or less. Here, a photocatalyst member having a decomposition capacity of 1000 ppm is used. The decomposition ability can be achieved by adjusting the amount of catalyst and the contact time with the catalyst according to the flow rate. Then, gas exceeding the decomposition capability is introduced into the decomposition unit 21. Initially, since ethylene oxide in the gas is mainly decomposed, the photocatalytic decomposition capacity is limited to 1000 ppm, and the processing capacity is also 1000 ppm. At the same time, ethylene oxide is adsorbed on the photocatalyst without being decomposed. After 5 hours, the ethylene oxide concentration in the gas becomes less than the decomposition ability of the catalyst, but since the photocatalyst has adsorbed ethylene oxide, the photocatalyst decomposes this ethylene oxide with surplus capacity. After 10 hours, the ethylene oxide concentration in the gas becomes approximately 0 ppm.

  The present invention is used for the treatment of exhaust gas containing ethylene oxide discharged from an ethylene oxide sterilization apparatus, and can be installed later on an existing ethylene oxide sterilization apparatus. Moreover, it can respond to various ethylene oxide sterilizers.

It is a schematic block diagram which shows an example of the decomposition processing apparatus of this invention. It is a schematic block diagram which shows an example of the buffer part in this invention. It is a schematic block diagram which shows the 1st example of the composite form which combined the photocatalyst and the plasma. It is a graph which shows the example of the time change of the discharge | emission amount of the waste gas discharged | emitted from a sterilization chamber. It is a graph which shows an example of the time change of the ethylene oxide density | concentration in the waste gas discharged | emitted from a sterilizer, and the time change of the ethylene oxide density | concentration in the waste gas discharged | emitted from the 1st, 2nd aeration tank part. It is a schematic block diagram which shows the decomposition processing apparatus of the ethylene oxide in a prior invention.

Explanation of symbols

21 ... Buffer unit, 22A ... First aeration tank, 22B ... Second aeration tank, 23A (23B) ... Air diffuser, 31 ... Decomposition unit, 41 ... Exhaust unit, 51 ... Decomposition treatment equipment, 61 ... Water treatment equipment

Claims (5)

Exhaust gas containing ethylene oxide is introduced, and has a buffer part that reduces the ethylene oxide concentration in the exhaust gas, and a decomposition part that decomposes ethylene oxide in the exhaust gas from the buffer part,
The decomposition portion is a photocatalytic member in which a titanium oxide powder having an ability to decompose ethylene oxide or a titanium oxide powder compression-molded is supported on a carrier made of titanium oxide, or a titanium oxide powder or a titanium oxide powder is compression-molded. An ethylene oxide decomposition treatment apparatus comprising a photocatalyst device having a photocatalyst member fixed to a substrate made of titanium oxide with a resin binder.   2. The ethylene oxide decomposition treatment apparatus according to claim 1, wherein the buffer unit is an aeration tank provided with a water tank filled with water and an air diffuser pipe for aeration of ethylene oxide in the water in the water tank.   3. The ethylene oxide decomposition treatment apparatus according to claim 1, wherein an exhaust device that makes the buffer unit and the decomposition unit have a negative pressure is provided downstream of the decomposition unit. 4. The ethylene oxide decomposition apparatus according to claim 2 or 3, wherein two or more aeration tanks are provided in series.   The water treatment part provided with the photocatalyst member is connected to the decomposition treatment apparatus according to any one of claims 1 to 4, and water in the water tank forming the buffer part is sent to the water treatment part. An ethylene oxide decomposition treatment apparatus characterized by decomposing ethylene oxide dissolved in water.

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