JP2011050819A - Exhaust gas cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning apparatus capable of effectively removing nitrogen oxide in an exhaust gas discharged from a sterilizing apparatus and the like with a simple configuration. <P>SOLUTION: The exhaust gas cleaning apparatus 50 that cleans the exhaust gas in a treating device 1 performing a predetermined treatment using a gas containing a high concentration nitrogen oxide includes a reduction gas supply section 53 that supplies a reduction gas and a plasma reaction section (plasma nozzle 31) that plasmatizes the reduction gas supplied from the reduction gas supply section 53, and reduces nitrogen oxide to detoxify the same by allowing the plasma to react with nitrogen oxide in the exhaust gas discharged from the treating device 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas purifying apparatus that purifies exhaust gas from a processing apparatus that performs a predetermined process using a gas containing a high concentration of nitrogen oxides.

  Conventionally, as disclosed in Patent Document 1, a sterilizing factor composed of a plasma-like noble gas or the like generated by a plasma generator is treated with a medical instrument or a food packaging material or the like disposed in a sealed chamber. In the sterilization apparatus configured to highly sterilize an object to be processed by contacting with an exhaust gas, an exhaust gas purification apparatus is provided for reducing the environmental impact of the sterilizing factor remaining in the exhaust gas from the sealed chamber Things have been done.

Further, as shown in Patent Document 2, ammonia (NH ₃ ) is injected as a reducing agent into a catalyst having denitration performance in a denitration system that removes nitrogen oxides (NOx) from combustion gas discharged from a combustion furnace. The amount of nitrogen oxides discharged into the atmosphere is reduced as much as possible by a selective catalytic reduction method (so-called SCR method) in which ammonia reacts with nitrogen oxides in the combustion gas.

Japanese Patent No. 3106695 JP 2000-70676 A

When nitrogen dioxide gas is used as a sterilization factor for the sterilization apparatus disclosed in Patent Document 1, nitrogen dioxide is introduced into the exhaust gas purification apparatus, ozone (O ₃ ) is supplied to the exhaust gas purification apparatus, and these are reacted. by adopting the configuration in which with adsorption filter nitrate produced (HNO ₃₎ by, it is possible to reduce the concentration of nitrogen oxides in exhaust gas discharged from the sterilization apparatus effectively. However, the exhaust gas purifying apparatus having the above-described configuration requires expensive ozone generating means (ozonizer) for supplying ozone, and it is inevitable that the manufacturing cost becomes high.

  On the other hand, when it is configured to remove nitrogen oxides (NOx) in exhaust gas by the SCR method disclosed in Patent Document 2, the manufacturing cost of the apparatus can be suppressed at a lower cost than that using the ozonizer. Is possible. However, the SCR method provides a sufficient NOx removal effect when the concentration of nitrogen oxides in the exhaust gas is, for example, about several hundred ppm. On the other hand, since the exhaust gas containing nitrogen oxide of extremely high concentration, for example, about several tens of thousands of ppm is discharged from the sterilizer, it is difficult to sufficiently remove the nitrogen oxide of high concentration by the SCR method. It was.

  In view of the foregoing, the present invention provides an exhaust gas purifying apparatus capable of effectively removing nitrogen oxides in exhaust gas derived from a processing apparatus using a gas containing a high concentration of nitrogen oxide with a simple configuration. The purpose is to provide.

  An exhaust gas purifying apparatus according to one aspect of the present invention that achieves the above object purifies the exhaust gas of a processing apparatus that performs a predetermined process using a gas containing high-concentration nitrogen oxide, and is a reducing gas. And reducing gas supplied from the reducing gas supply unit into plasma and reducing nitrogen oxides by reacting with nitrogen oxides in the exhaust gas derived from the processing apparatus. And a plasma reaction part that is rendered harmless (claim 1).

  According to this configuration, even when exhaust gas containing an extremely high concentration of nitrogen oxides is discharged from the processing device while preventing the manufacturing cost of the exhaust gas purification device from increasing, the nitrogen oxides in the exhaust gas Can be efficiently reduced and discharged in a detoxified state.

  In the above configuration, the plasma reaction unit converts the reduction gas composed of hydrogen gas supplied from the reduction gas supply unit into plasma, reduces nitrogen oxide by reacting with nitrogen oxide in the exhaust gas, and reduces the reduction gas. It can be set as the structure provided with the ammonia filter which adsorb | sucks the ammonia produced | generated by reaction (Claim 2).

  According to this configuration, the nitrogen oxides in the exhaust gas can be effectively reduced and rendered harmless, and ammonia generated by this reduction reaction can be reliably prevented from being discharged to the outside.

  In the above-described configuration, the processing apparatus includes a processing unit that sterilizes the processing object by reacting the processing object with nitrogen dioxide, a storage unit having a sealed space into which air is introduced, and air in the storage unit. It is desirable to have a plasma generation unit that generates nitrogen oxides by converting to plasma, and the plasma generation unit is used as a plasma reaction unit for exhaust gas purification.

  According to this configuration, the plasma generator for generating nitrogen oxide for sterilization can be combined with the function as the plasma reaction unit for the exhaust gas purifying device, so that the structure of the device is effectively simplified. There is an advantage that it can be downsized.

  According to the present invention, even when exhaust gas containing a very high concentration of nitrogen oxides is discharged from the treatment apparatus, nitrogen oxides in the exhaust gas can be effectively removed and rendered harmless, and an ozonizer is used. An exhaust gas purification device that can prevent the manufacturing cost from becoming expensive can be provided.

It is a block diagram which shows an example of the processing apparatus provided with the exhaust gas purification apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of a microwave supply apparatus roughly. It is sectional drawing which shows the plasma nozzle of the state attached to the waveguide. It is a block diagram showing a detailed configuration of the NO ₂ conversion unit. It is detailed explanatory drawing which shows the structure of an exhaust gas purification apparatus. It is a block diagram which shows the electrical control system of a processing apparatus. It is a timing chart which shows operation | movement of a processing apparatus. It is a table format figure which shows the control state of a pump. It is a table format figure which shows the control state of a solenoid valve.

FIG. 1 shows an example of a processing apparatus 1 including an exhaust gas purifying apparatus 50 according to an embodiment of the present invention. The processing apparatus 1 uses, for example, medical instruments such as a scalpel, forceps, and catheter, and food packaging materials such as packaging sheets, trays, and bottles as objects to be processed, and applies sterilization gas to these to perform sterilization. Device. In the present embodiment, an example in which nitrogen dioxide (NO ₂ ) is used as a sterilization gas is shown.

  The processing apparatus 1 includes a main chamber (processing section) 11, a sub chamber (storage section) 12, an intake system 20, a circulation system 30, a linkage system 40, and an exhaust gas purification apparatus 50 according to the present invention. The first to eighth electromagnetic valves V1 to V8 and the first pump P1 to the fourth pump P4 are disposed at appropriate positions of the systems 20 to 40 and the exhaust gas purification device 50.

  The main chamber 11 is a chamber that provides a sealed space in which an object to be processed is accommodated. The main chamber 11 is a large-capacity chamber that is made of, for example, stainless steel and has a pressure resistant structure that can cope with high vacuuming. Although not shown, the main chamber 11 is provided with a door for loading and unloading a workpiece, and a processing tray for loading the workpiece is provided therein.

The main chamber 11 is provided with a first concentration sensor 111 that measures the concentration of the sterilizing gas and a first pressure sensor 112 that detects the pressure in the chamber. The first concentration sensor 111 measures the concentration of nitrogen dioxide (NO ₂ ) as a sterilization gas. When exhausting the gas in the main chamber 11 after the sterilization process, the measured value of the first concentration sensor 111 is referred to. Is done. The first pressure sensor 112 is a sensor that measures the reduced pressure state in the main chamber 11. In addition, it is good also as a structure provided with various physical quantity sensors, such as a temperature sensor, a humidity sensor, or an ozone sensor.

The sub-chamber 12 is a chamber for generating a sterilizing gas, and is made of, for example, stainless steel. Like the main chamber 11, the sub-chamber 12 is a relatively small-capacity chamber having a pressure-resistant structure capable of handling a high degree of evacuation. is there. As will be described later, NO ₂ gas having a predetermined concentration is generated in the sub-chamber 12 under normal pressure, and the NO ₂ gas is introduced into the main chamber 11 under reduced pressure.

The sub-chamber 12 is also provided with a second concentration sensor 121 that measures the NO ₂ concentration and a second pressure sensor 122 that detects the pressure in the chamber. The measured value of the second concentration sensor 121 is referred to, for example, to confirm whether or not NO ₂ gas having a predetermined concentration is generated in the sub-chamber 12 before introducing NO ₂ gas into the main chamber 11. .

  The intake system 20 is a piping system for introducing dried outside air (air) into the sub chamber 12 or both the sub chamber 12 and the main chamber 11. The intake system 20 includes a first pump P1, an air dryer 21, a humidity sensor 22, a first electromagnetic valve V1, a first atmospheric pressure pipe 201, and a first vacuum pipe 202. The first normal pressure pipe 201 is a pipe connecting the first pump P1 and the first electromagnetic valve V1, and the air dryer 21 and the humidity sensor 22 are arranged in the path. The first vacuum pipe 202 connects between the first electromagnetic valve V <b> 1 and the subchamber 12.

  The first pump P1 is a pump that is operated when the sub-chamber 12 in a reduced pressure state or both the sub-chamber 12 and the main chamber 11 are returned to normal pressure. The first pump P <b> 1 sucks outside air and sends the outside air into the sub chamber 12 through the first normal pressure pipe 201 and the first vacuum pipe 202. The air dryer 21 removes moisture contained in the outside air. For example, a drying device including an electric heater is applied. The air that has passed through the air dryer 21 has substantially zero humidity. The humidity sensor 22 detects the humidity of the air flowing through the first normal pressure pipe 201. The humidity sensor 22 is exclusively used for detecting a failure of the air dryer 21.

  The first electromagnetic valve V1 is a valve that is “opened” in conjunction with the operation of the first pump P1. That is, the first electromagnetic valve V1 is “closed” when the system including the main chamber 11 and the sub-chamber 12 needs to be shut off from the external pressure, and “open” when the system is returned to normal pressure. Is done. For this reason, the first vacuum pipe 202 having resistance to evacuation is used downstream of the first electromagnetic valve V1 in the intake direction.

The circulation system 30 is a system that is operated when dry air introduced into the sub-chamber 12 by the intake system 20 is mainly ionized with plasma to generate NO ₂ gas as a sterilization gas. The circulation system 30 includes a second electromagnetic valve V2, a third electromagnetic valve V3, a plasma nozzle 31, a gas flow meter 32, a second pump P2, a NO ₂ conversion unit 33, a second vacuum pipe 301, a third vacuum pipe 302, and A second atmospheric pressure pipe 303 is included.

One end side of the second vacuum pipe 301 communicates with the sub-chamber 12, and the other end side is connected to one end side of the second atmospheric pressure pipe 303 via the second electromagnetic valve V2. One end side of the third vacuum pipe 302 communicates with the sub-chamber 12, and the other end side is connected to the other end side of the second atmospheric pressure pipe 303 via the third electromagnetic valve V3. Thereby, a loop line that communicates with the sub-chamber 12 and returns to one end side of the third vacuum pipe 302 starting from one end side of the second vacuum pipe 301 is formed. In the present embodiment, the second vacuum pipe 301 side is the upstream side of the air flow flowing in the loop pipe line. A plasma nozzle 31, a gas flow meter 32, a second pump P <b> 2, and a NO ₂ conversion unit 33 are arranged in order from the upstream side with respect to the second atmospheric pressure pipe 303.

The second solenoid valve V2 and the third solenoid valve V3 are valves that are “closed” when the sub-chamber 12 is in a depressurized state, and are “open” when NO ₂ gas is generated in a normal pressure state, which will be described later. is there. For this reason, the second vacuum pipe 301 and the third vacuum pipe 302 are applied as pipes connecting the second electromagnetic valve V2 and the third electromagnetic valve V3 and the sub-chamber 12.

The plasma nozzle 31 provides an electric field concentration part for generating plasma (ionized gas). The air (gas containing nitrogen and oxygen) flowing through the second atmospheric pressure pipe 303 is ionized by passing through the electric field concentration portion of the plasma nozzle 31, and is subjected to nitrogen dioxide (NO ₂ ) gas or nitrogen monoxide (NO). It is converted into nitrogen oxide (NOx) gas containing gas. In order to generate such plasma, in this embodiment, microwave energy is used. The microwave energy is given to the plasma nozzle 31 from the microwave supply device 60.

  FIG. 2 is a block diagram schematically showing the configuration of the microwave supply device 60. The microwave supply device 60 is a device for generating microwave energy and supplying the microwave energy to the plasma nozzle 31, and a microwave generation device 61 for generating a microwave and a waveguide for propagating the microwave. A tube 62. The plasma nozzle 31 is attached to the waveguide 62. An isolator 63, a coupler 64, and a tuner 65 are provided between the microwave generator 61 and the waveguide 62.

  The microwave generator 61 includes, for example, a microwave generation source such as a magnetron that generates a microwave of 2.45 GHz, and an amplifier that adjusts the intensity of the microwave generated by the microwave generation source to a predetermined output intensity. Including. In the present embodiment, for example, a continuously variable microwave generator 61 that can output microwave energy of 1 W to 3 kW is preferably used.

  The waveguide 62 is made of a nonmagnetic metal such as aluminum, has a long tubular shape with a rectangular cross section, and propagates the microwave generated by the microwave generator 61 in the longitudinal direction thereof. A sliding short 621 is attached to the far end side of the waveguide 62 via a flange portion 622. The sliding short 621 is a member for adjusting the standing wave pattern by changing the reflection position of the microwave.

  The isolator 63 is a device that suppresses the incident of the reflected microwave from the waveguide 62 to the microwave generator 61, and includes a circulator 631 and a dummy load 632. The circulator 631 directs the microwave generated by the microwave generator 61 toward the waveguide 62 while directing the reflected microwave toward the dummy load 632. The dummy load 632 absorbs the reflected microwave and converts it into heat. The coupler 64 measures the intensity of the microwave energy. The tuner 65 includes a stub that can project into the waveguide 62, and is an apparatus for performing adjustment that minimizes the reflected microwave, that is, adjustment that maximizes the consumption of microwave energy at the plasma nozzle 31. . The coupler 64 is used for this adjustment.

  FIG. 3 is a cross-sectional view showing the plasma nozzle 31 attached to the waveguide 62. The plasma nozzle 31 includes a center conductor 311, an outer conductor 312, a spacer 313, and a protective tube 314. The center conductor 311 is made of a rod-shaped member made of a highly conductive metal, and a portion on the upper end 311 </ b> B side projects into the waveguide 62 by a predetermined length. The protruding upper end portion 311B functions as an antenna portion that receives the microwave propagating in the waveguide 62.

  The outer conductor 312 is a cylindrical body made of a highly conductive metal and having a cylindrical space 312H (plasma generation space) that houses the central conductor 311. The central conductor 311 is disposed on the central axis of the cylindrical space 312H. The outer conductor 312 is fixed to the waveguide 62 by being fitted into a cylindrical metal flange plate 623 integrally attached to the lower surface plate of the waveguide 62 and tightened with a screw 624. As a result of the waveguide 62 being grounded, the outer conductor 312 is also grounded.

  The outer conductor 312 has a gas supply hole 312N that penetrates from the outer peripheral wall to the cylindrical space 312H. The upstream side of the second normal pressure pipe 303 is connected to the gas supply hole 312N. On the other hand, an insulating pipe 315 is connected to the lower end of the cylindrical space 312H. The pipe 315 constitutes a part of the second normal pressure pipe 303. Thereby, the gas which distribute | circulates the inside of the 2nd normal pressure piping 303 passes through the inside of the cylindrical space 312H.

  The spacer 313 holds the central conductor 311 and seals the space between the waveguide 62 and the cylindrical space 312H. As the spacer 313, for example, an insulating member made of a heat-resistant resin material such as polytetrafluoroethylene, ceramic, or the like can be used. A step portion is provided at the upper end portion of the cylindrical space 312H of the outer conductor 312 and the spacer 313 is supported by the step portion. The center conductor 311 held by the spacer 313 is insulated from the outer conductor 312. The protection tube 314 is made of a quartz glass pipe or the like having a predetermined length, and is fitted into the lower end portion of the cylindrical space 312H in order to prevent abnormal discharge (arcing) at the lower end edge 312T of the outer conductor 312.

  According to the plasma nozzle 31 configured as described above, when the center conductor 311 receives the microwave propagating through the waveguide 62, a potential difference is generated between the outer conductor 312 and the ground potential. In particular, an electric field concentration portion is formed in the vicinity of the lower end 311T of the center conductor 311 and the lower end edge 312T of the outer conductor 312. In this state, when a gas (air) containing oxygen molecules and nitrogen molecules is supplied from the gas supply hole 312N to the cylindrical space 312H, the gas is excited to generate plasma (ionized gas) in the vicinity of the lower end portion 311T of the center conductor 311. ) Occurs. The plasma contains NOx and free radicals. Although this plasma has an electron temperature of several tens of thousands of degrees, the gas temperature is a reactive plasma that is close to the outside temperature (a plasma in which the electron temperature indicated by electrons is extremely high compared to the gas temperature indicated by neutral molecules). It is a plasma generated under normal pressure.

Returning to FIG. 1, the gas flow meter 32 measures the flow rate of the gas flowing through the second atmospheric pressure pipe 303. The second pump P2 is a pump for circulating the gas in one space constituted by the sub-chamber 12 and the loop line of the circulation system 30 when the NO ₂ gas is generated. When the second pump P2 is operated while the plasma nozzle 31 is operating, the gas repeatedly passes through the cylindrical space 312H that generates plasma, and the NO ₂ concentration gradually increases. As the second pump P2, a chemical-resistant pump having resistance to NOx or the like is used.

The NO ₂ conversion unit 33 has a function of extracting NO ₂ from a gas that passes through a plasma generation unit including the plasma nozzle 31 and contains various substances. FIG. 4 is a block diagram showing a detailed configuration of the NO ₂ conversion unit 33. The NO ₂ conversion unit 33 is a filter 331 that adsorbs nitric acid (HNO ₃ ) from the gas sent out from the plasma nozzle 31, and a first conversion that converts NOx in the gas that has passed through the filter 331 into nitrogen monoxide (NO). Unit 332 and then a second conversion unit 333 that converts the NO into NO ₂ .

When air is ionized in the plasma nozzle 31, NO (nitrogen monoxide) and O ₃ (ozone) are generated. These are oxidized stepwise by the reaction according to the following formula, and eventually are partly converted to HNO ₃ (nitric acid) by the reaction with the moisture remaining slightly without being completely removed by the air dryer 21.

NO + O ₃ → NO ₂ + O ₂
2NO ₂ + O ₃ → N ₂ O ₅ + O ₂
N ₂ O ₅ + H ₂ O → 2HNO ₃
The filter 331 has a function of adsorbing HNO ₃ produced by the above reaction. As the filter 331, for example, a filter in which a nitric acid-adsorbing coating layer is applied to a base material having a ceramic honeycomb structure can be used. As the nitric acid-adsorbing coating layer, for example, a silicon adsorbent such as zeolite, alumina, or silica gel can be used.

The first converter 332 converts NOx other than NO ₂ contained in the gas that has passed through the filter 331 into NO. As the first converter 332, for example, a catalyst including a catalyst in which a coating layer containing platinum, palladium, or the like is formed on a substrate having a ceramic honeycomb structure, and a heater that adjusts the temperature of the catalyst. An apparatus can be used.

Second converter 333 converts the NO contained in the gas passing through the first converter 332 into NO _2. Similarly, the second conversion unit 333 includes a catalyst in which a coating layer containing platinum, palladium, or the like is formed on a base material having a ceramic honeycomb structure, and the temperature of the catalyst (of the first conversion unit 332). A catalyst device provided with a heater for adjusting the temperature (different from the catalyst) can be used.

  Next, the linkage system 40 is a system for communicating between the main chamber 11 and the sub chamber 12. The linkage system 40 includes a fourth electromagnetic valve V4, a fifth electromagnetic valve V5, a third pump P3, a fourth vacuum pipe 401, and a fifth vacuum pipe 402.

One end (upstream end) of the fourth vacuum pipe 401 is connected to the sub chamber 12, and the other end (downstream end) is connected to the main chamber 11. A third pump P3 is disposed upstream of the fourth vacuum pipe 401, and a fourth electromagnetic valve V4 is disposed downstream. The third pump P3 is a chemical-resistant pump, and when the sub-chamber 12 is evacuated, when NO ₂ gas is introduced (circulated) from the sub-chamber 12 to the main chamber 11 for sterilization, It operates when the chamber 11 is discharged and detoxified. The fourth solenoid valve V4 is a valve that is “opened” when the third pump P3 operates.

  One end side (upstream end) of the fifth vacuum pipe 402 is connected to the main chamber 11, and the other end side (downstream end) is connected to the sub-chamber 12. The fifth solenoid valve V5 is attached to the fifth vacuum pipe 402. The fifth electromagnetic valve V5 is a valve that is “opened” when the main chamber 11 and the sub-chamber 12 are returned to normal pressure during sterilization.

The processing apparatus 1 includes an exhaust gas purification device 50 that detoxifies the NO ₂ gas used for sterilization and discharges it to the outside. As shown in FIG. 5, the exhaust gas purification device 50 includes first and second exhaust pipes 51 and 52 connected to the main chamber 11, a sixth electromagnetic valve V <b> 6 and a fourth pump provided in the first exhaust pipe 51. An ammonia filter comprising a reducing gas supply unit 53 for supplying a reducing gas containing P4 and hydrogen gas (H ₂ ) to the plasma generation space of the plasma nozzle 31, and a natural zeolite provided in the second exhaust pipe 52 54 and seventh and eighth electromagnetic valves V7 and V8.

  The sixth electromagnetic valve V6 disposed in the first discharge pipe 51 is a valve that is “opened” when the main chamber 11 and the sub chamber 12 are depressurized. The first discharge pipe 51 has a vacuum pipe at the upstream side of the installation portion of the sixth electromagnetic valve V6 and a normal pressure pipe at the downstream side thereof. At the downstream end of the first discharge pipe 51, a fourth pump P <b> 4 is provided that is a vacuum pump that evacuates the main chamber 11 and the sub-chamber 12 and discharges exhaust gas to the outside air during exhaust.

  The second discharge pipe 52 is located on the downstream side of the seventh electromagnetic valve V7, the vacuum pipe 521 located on the upstream side of the installation part of the seventh electromagnetic valve V7, and the downstream end is located downstream of the plasma generation space. The exhaust gas supply pipe 522 communicates, a direction control valve 523 provided in the downstream portion of the plasma nozzle 31, and a processing gas outlet pipe 524 connected to the direction control valve 523. The processing gas outlet pipe 524 is provided with an ammonia filter 54 and an eighth electromagnetic valve V8.

  The downstream end of the processing gas outlet pipe 524 is connected to the first discharge pipe 51 at the upstream side portion of the fourth pump P. The processing gas led out from the plasma nozzle 31 is led out to the processing gas lead-out pipe 524 side through the direction control valve 523, and is led out to the first exhaust pipe 51 through the processing gas lead-out pipe 524. It is discharged to the outside through the 4 pump P4.

The reducing gas supply unit 53 includes a reducing gas tank 531 containing a reducing gas containing hydrogen gas (H ₂ ) or other reducing gas such as hydrocarbon gas (HC), and a reducing gas in the reducing gas tank 531. Is supplied to the plasma generation space of the plasma nozzle 31, and an open / close valve 533 provided in the reducing gas supply pipe 532.

In the present embodiment, a reducing gas composed of a mixed gas of about 4% hydrogen gas (H ₂ ) and about 96% nitrogen gas (N ₂ ) is stored in the reducing gas tank 531 in a compressed state. Then, when the on-off valve 533 is opened, the reducing gas in the reducing gas tank 531 is supplied to the plasma generation space of the plasma nozzle 31 through the reducing gas supply pipe 532 according to the pressure, and the reducing gas is supplied. Is turned into plasma. The hydrogen gas concentration is set to the above value (about 4%) for explosion prevention.

  During the detoxification process of the exhaust gas derived from the main chamber 11 and the sub chamber 12, the sixth electromagnetic valve V6 of the first exhaust pipe 51 is “closed” and the seventh and eighth electromagnetics of the second exhaust pipe 52 are closed. The valves V7 and V8 are “open”, and the direction of the processing gas from the plasma nozzle 31 is switched to the processing gas outlet tube 524 side by the direction control valve 523. In this state, when the fourth pump P4 is in an operating state, the exhaust gas is supplied to the downstream portion of the plasma generation space of the plasma nozzle 31 through the second discharge pipe 52.

Further, when the on-off valve 533 of the reducing gas supply unit 53 is “opened”, the reducing gas made of H ₂ or the like supplied via the reducing gas supply pipe 532 is allowed to flow in the plasma generation space of the plasma nozzle 31. While being converted into plasma, NH ₃ and H ₂ O are generated as a result of the reaction between the nitrogen oxide composed of NO ₂ or the like in the exhaust gas and the reducing gas converted into plasma in the downstream portion.

2NO ₂ + 7H ₂ → 2NH ₃ + 4H ₂ O
The exhaust gas purified by reducing nitrogen oxide (NOx) in this way is removed from the process gas outlet pipe 524 after the ammonia (NH ₃ ) component in the exhaust gas is removed by the ammonia filter 54. It is led out to the discharge pipe 51 and discharged to the outside through the first discharge pipe 51. Note that a drying agent such as silica gel that absorbs water (H ₂ O) generated in accordance with the reduction reaction may be provided in the processing gas outlet tube 524.

  Next, an electrical control configuration of the processing apparatus 1 will be described with reference to FIG. The processing device 1 is provided with a control device 70 (not shown in FIG. 1) for electrically controlling the operation of the processing device 1. As shown in FIG. 6, the control device 70 includes an overall control unit 71, a pump control unit 72, a solenoid valve control unit 73, a plasma control unit 74, a lock control unit 75, a dryer control unit 76, and an exhaust gas purification control unit 77. ing.

The overall control unit 71 manages the overall operation mode of the processing apparatus 1 and gives a control signal for notifying the individual control units 72 to 77 of the change and maintenance of the operation mode. The NO ₂ concentration data in the main chamber 11 and the sub chamber 12 measured by the first and second concentration sensors 111 and 121, and the data in the main chamber 11 and the sub chamber 12 measured by the first and second pressure sensors 112 and 122, respectively. The pressure data is input to the overall control unit 71. The overall control unit 71 manages the operation mode of the processing device 1 based on the concentration data and pressure data, time data provided from a timer device (not shown), and the like.

  The pump control unit 72 gives the first to fourth pumps P1 to P4 control signals that individually control the execution and stop of the pump operation according to each operation mode. The solenoid valve control unit 73 gives a control signal for “open” or “close” individually to the first to eighth solenoid valves V1 to V8 according to the operation mode.

  The plasma control unit 74 gives the microwave supply device 60 a control signal for controlling the start or stop thereof. That is, the plasma control unit 74 controls a period for generating plasma in the plasma nozzle 31.

  The lock control unit 75 controls the operation of the chamber lock device 13. The chamber lock device 13 is a device that interlocks an opening / closing door for loading and unloading an object to be processed provided in the main chamber 11 (not shown in FIG. 1). The door of the main chamber 11 is locked by a chamber lock device 13 for ensuring safety during a series of sterilization processes for an object to be processed.

  The dryer control unit 76 controls the ON-OFF operation of the air dryer 21. Humidity data measured by the humidity sensor 22 is output to the dryer control unit 76. When the humidity data is an abnormal value indicating that the air dryer 21 has failed in operation, the dryer control unit 76 outputs an abnormal signal to the overall control unit 71 to notify the user of the abnormality.

  The exhaust gas purification control unit 77 removes NOx in the exhaust gas derived from the main chamber 11 and renders it harmless by opening the on-off valve 533 of the reducing gas supply unit 53 to open the reducing gas in the reducing gas tank 531. Control to be supplied to the installation part of the plasma nozzle 31 is executed.

  FIG. 7 is a timing chart showing the operation of the processing device 1 controlled by the control device 70. 8 is a tabular diagram showing the control states of the first to fourth pumps P1 to P4, and FIG. 9 is a tabular diagram showing the control states of the first to eighth electromagnetic valves V1 to V8. . In FIG. 8, a circle indicates that the pump is operating and a cross indicates that the pump is stopped. In FIG. 9, a circle indicates that the solenoid valve is “open”, and a cross indicates that it is “closed”. Each state is shown. Note that one “process content” column in the horizontal column of FIG. 7 is linked to the “process” column in the leftmost vertical column of FIGS. 8 and 9.

Time T1 is the time when the user presses the start button of the processing apparatus 1 and a series of sterilization processing steps are started. As shown in FIG. 7, the sterilization process includes a first drying process for drying the object to be processed, a sterilization preparation process for generating NO ₂ gas as a sterilization gas, and bringing the object to be processed into contact with NO ₂ gas. A sterilization process for sterilizing the object to be processed, an exhaust gas detoxification process for purifying and discharging NO ₂ gas remaining after the sterilization process, and a second drying process for drying the object to be processed again. It is assumed that an object to be processed such as a medical instrument is accommodated in the main chamber 11 before time T1.

The first drying process includes an evacuation process for highly evacuating the main chamber 11 and the sub-chamber 12, a holding process for maintaining the state for a certain period of time, and dry air that is a raw material for generating NO ₂ gas in the sub-chamber 12. And the intake process.

  The overall control unit 71 of the control device 70 first gives an instruction to lock the open / close door of the main chamber 11 to the lock control unit 75 at time T1. In response to this, the lock controller 75 drives the chamber lock device 13 to interlock the open / close door of the main chamber 11. In addition, in order to execute the exhaust process, the operation mode is set to “exhaust mode”, and the mode setting signal is notified to each of the individual control units 72 to 77.

  When the exhaust mode is set, the pump control unit 72 operates the third and fourth pumps P3 and P4, and the electromagnetic valve control unit 73 sets the fourth and sixth electromagnetic valves V4 and V6 to “open”. . By only opening these solenoid valves, an exhaust path is formed from the sub chamber 12 to the fourth pump P4 through the fourth vacuum pipe 401, the main chamber 11 and the first exhaust pipe 51. Then, the main chamber 11 and the sub chamber 12 are evacuated by driving the third and fourth pumps P3 and P4.

  The overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every predetermined sampling period, and monitors the pressures of the main chamber 11 and the sub chamber 12. If it is determined based on the pressure data that the predetermined degree of vacuum (1 Torr is illustrated in FIG. 7) has been reached at time T2, the overall control unit 71 sets the operation mode to “holding mode” in order to execute the holding step. To do.

  The holding mode is a mode in which all of the first to fourth pumps P1 to P4 are stopped and all of the first to eighth electromagnetic valves V1 to V8 are “closed”. In FIGS. 8 and 9, the state of the holding process corresponding to this holding mode is not shown. Therefore, when the holding mode is set, the pump control unit 72 stops the third and fourth pumps P3 and P4, and the electromagnetic valve control unit 73 sets the fourth, sixth, seventh, and eighth electromagnetic valves V4. , V6, V7, V8 are “closed”. The overall control unit 71 causes the timer device to start timing from time T2, and maintains the holding mode until time T3 when a predetermined time elapses. By continuing this holding process for a certain period of time, the inside of the main chamber 11, the object to be processed accommodated therein, and the inside of the sub-chamber 12 are brought into a dry state. Further, the vacuum state in the main chamber 11 and the sub chamber 12 is stabilized.

  At time T3, the overall control unit 71 sets the operation mode to “intake mode” for execution of the intake process. Since the intake process is intended to introduce dry air into the sub-chamber 12 under reduced pressure, the pump control unit 72 operates only the first pump P1, and the electromagnetic valve control unit 73 operates the first electromagnetic valve V1. Only “open”. The dryer control unit 76 operates the air dryer 21. In this state, the air sucked from the outside by the first pump P1 is highly dried by the air dryer 21 and passes through the first normal pressure pipe 201 and the first vacuum pipe 202 into the subchamber 12. be introduced. The drying process is continued in the main chamber 11 during this intake process (and during the next sterilization preparation process).

  During the intake mode, the overall control unit 71 receives pressure data from the second pressure sensor 122 every sampling period and monitors the pressure in the sub-chamber 12. If it is determined that the normal pressure (760 Torr) has been reached at time T4 based on the pressure data, the overall control unit 71 ends the intake mode. Further, the dryer control unit 76 stops the air dryer 21.

Subsequently, a sterilization preparation process is executed. This step comprises a plasma step of generating NO ₂ gas by ionizing air with plasma in order to fill the sub-chamber 12 with a predetermined concentration of sterilizing gas.

At time T4, the overall control unit 71 sets the operation mode to “plasma mode” for the execution of the plasma process. When the plasma mode is set, the pump control unit 72 operates only the second pump P2, and the electromagnetic valve control unit 73 opens the second and third electromagnetic valves V2 and V3. Thereby, one sealed space constituted by the sub-chamber 12, the second vacuum pipe 301, the second atmospheric pressure pipe 303, and the third vacuum pipe 302 is formed, and air (NO ₂ gas) circulates in the sealed space. It becomes possible to do.

At time T4, the plasma control unit 74 operates the microwave supply device 60. Accordingly, the microwave supply device 60 supplies microwave energy to the plasma nozzle 31, and plasma is generated at the plasma nozzle 31. At this time, the cylindrical space 312H is in a state where the pressure is reduced from the atmospheric pressure in accordance with the operation of the second pump P2, so that the plasma lighting property is good and the lighting state is well maintained. The air circulating through the plasma nozzle 31 is ionized and further converted into NO ₂ gas by passing through the NO ₂ converter 33. By continuing this state, the air in the sub-chamber 12 is gradually converted into NO ₂ gas.

During the plasma mode, the overall control unit 71 receives NO ₂ concentration data from the second concentration sensor 121 for each sampling period, and monitors the NO ₂ concentration in the sub-chamber 12. If it is determined that the NO ₂ concentration has reached the predetermined value at time T5 based on the concentration data, the overall control unit 71 ends the plasma mode. Accordingly, the plasma control unit 74 stops the operation of the microwave supply device 60.

Next, a sterilization process is performed. In the sterilization process, NO ₂ gas filled in the sub-chamber 12 under normal pressure is used to store the object to be processed in the main chamber 11 under high vacuum, using the pressure difference between the two chambers 11 and 12. This is a step of bringing NO ₂ gas into contact with an object to be treated for a certain period of time suitable for sufficient sterilization while being introduced at once.

  At time T5, the overall control unit 71 sets the operation mode to “circulation mode” for the execution of the sterilization process. When the circulation mode is set, the pump control unit 72 operates only the third pump P3, and the electromagnetic valve control unit 73 opens the fourth and fifth electromagnetic valves V4 and V5. As a result, the main chamber 11 and the sub-chamber 12 become one sealed space connected by the fourth vacuum pipe 401 and the fifth vacuum pipe 402.

As a result, NO ₂ gas suddenly enters the main chamber 11 under reduced pressure, and the object to be processed in the main chamber 11 is well exposed to the NO ₂ gas. For example, even if the object to be processed is an elongated tube such as a catheter, NO ₂ gas spreads to the minute space in the tube, and the object to be processed is satisfactorily sterilized.

As the introduction of NO ₂ gas into the main chamber 11 progresses, the pressure difference between the main chamber 11 and the sub-chamber 12 decreases. At a certain time T51, the pressures in both the chambers 11 and 12 are balanced. After time T51, NO ₂ gas in the sub chamber 12 is sent to the main chamber 11 exclusively by the operation of the third pump P3. The overall control unit 71 causes the timer device to start measuring time from time T5 and maintains the circulation mode until time T6 when a predetermined time elapses.

By such a sterilization process, the object to be processed is in a sterilized state, but NO ₂ gas and a substance generated by the sterilization reaction remain in the main chamber 11 and the sub chamber 12. In order to purify these, an exhaust gas detoxification process is performed. This step includes a return step for returning the inside of the main chamber 11 and the sub chamber 12 to normal pressure, and a purification step for purifying residual NO ₂ gas and the like.

  At time T6, the overall control unit 71 sets the operation mode to “return mode” for execution of the return step. When the return mode is set, the pump control unit 72 newly operates the first pump P1, and continues the operation of the third pump P3. The solenoid valve control unit 73 sets the first and fourth solenoid valves V1 and V4 to “open”. As a result, outside air is introduced into the main chamber 11 and the sub chamber 12 in a reduced pressure state via the first atmospheric pressure pipe 201, the first vacuum pipe 202 and the fourth vacuum pipe 401.

  During the return mode, the overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period and monitors the pressures of the main chamber 11 and the sub chamber 12. If it is determined that both chambers have reached the normal pressure at time T7 based on the pressure data, the overall control unit 71 ends the return mode.

  At time T7, the overall control unit 71 sets the operation mode to “purification mode” in order to execute the purification process. When the purification mode is set, the pump control unit 72 puts the third and fourth pumps P3 and P4 into an operating state, and the electromagnetic valve control unit 73 sets the first, fourth, seventh, and eighth electromagnetic valves V1, V4, V7, and V8 are set to “open”, and the second, third, fifth, and sixth solenoid valves V2, V3, V5, and V6 are set to “closed”.

When the third and fourth pumps P3 and P4 are driven in the purification process, the residual NO ₂ gas in the main chamber 11 and the sub chamber 12 passes through the second exhaust pipe 51 and is reduced by the plasma nozzle 31. Supplied to the department. Further, the exhaust gas purification control unit 77 “opens” the on-off valve 533 of the reducing gas supply unit 53, and the plasma control unit 74 operates the microwave supply device 60. Thus, a detoxifying process is performed by reducing nitrogen oxides such as NO ₂ in the exhaust gas using the reducing gas supplied from the reducing gas tank 531 to the installation part of the plasma nozzle 31. .

By executing the purification mode processing as described above, NOx in the exhaust gas is reduced and removed, and NH ₃ remaining in the exhaust gas is adsorbed and removed by the ammonia filter 54, and then the eighth. It is discharged into the atmosphere through the electromagnetic valve V8 and the fourth pump P4.

  After completion of the purification mode, the sterilized object to be processed is dried, the main chamber 11 and the sub-chamber 12 are exhausted, and an exhaust process, a holding process, and a return process for removing residues are included. 2 Drying process is performed.

  That is, at time T8, the solenoid valve control unit 73 sets the seventh and eighth solenoid valves V7 and V8 to “closed” and the sixth solenoid valve V6 to “open”. Thereby, the gas in the main chamber 11 and the sub-chamber 12 is evacuated, and the purified gas after purification is discharged from the discharge pipe 51 to the outside. In the “exhaust mode”, the second and third electromagnetic valves V2 and V3 are “closed”, so that the plasma nozzle 31 having a relatively low resistance to vacuum can be protected.

  The overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period, and monitors the pressure in the main chamber 11 and the sub chamber 12. If it is determined that the predetermined degree of vacuum is reached at time T9 based on the pressure data, the overall control unit 71 sets the operation mode to “holding mode” in order to execute the holding step. As a result, all of the first to fourth pumps P1 to P4 are stopped, and all of the first to eighth electromagnetic valves V1 to V8 are “closed”.

  The overall control unit 71 causes the timer device to start timing from time T9 and maintains the holding mode until time T10 when a predetermined time elapses. By continuing this holding process for a certain time, the object to be processed is brought into a dry state, and the inside of the main chamber 11 and the sub chamber 12 is cleaned.

  At time T10, the overall control unit 71 sets the operation mode to “return mode”. When the return mode is set, the pump control unit 72 operates the first and third pumps P1 and P3, and the electromagnetic valve control unit 73 sets the first, fourth, and fifth electromagnetic valves V1, V4, and V5. “Open”. As a result, outside air is introduced into the main chamber 11 and the sub-chamber 12 in a decompressed state.

  During the return mode, the overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period and monitors the pressures of the main chamber 11 and the sub chamber 12. If it is determined that both chambers have reached the normal pressure at time T11 based on the pressure data, the overall control unit 71 ends the return mode. Further, the chamber lock device 13 is driven via the lock control unit 75 to release the interlock of the open / close door of the main chamber 11. By releasing the interlock, the user can take out the workpiece from the main chamber 11.

  According to the processing apparatus 1 demonstrated above, the to-be-processed object in the main chamber 11 can be sterilized using the gas containing a high concentration nitrogen oxide (NOx). The exhaust gas purifying device 50 that purifies the exhaust gas from the main chamber 11 of the processing apparatus 1 is supplied with a reducing gas, and a reducing gas supplied from the reducing gas supplying unit 53 is turned into plasma. Since a plasma reaction part for reducing and detoxifying nitrogen oxides by reacting with nitrogen oxides in the exhaust gas derived from the processing apparatus 1 is provided, an extremely high concentration of nitrogen oxides from the processing apparatus 1 is provided. Even when the exhaust gas including the exhaust gas is discharged, the nitrogen oxides in the exhaust gas can be effectively removed with a simple configuration and rendered harmless.

That is, in this embodiment, the exhaust gas derived from the main chamber 11 of the processing apparatus 1 and the reducing gas containing hydrogen gas (H ₂ ) supplied from the reducing gas tank 531 of the reducing gas supply unit 53 are circulated. The hydrogen gas (H ₂ ) is supplied to a plasma reaction section comprising a plasma nozzle 31 and the like provided at 30 to convert it into plasma and react with nitrogen oxide (NO x) comprising NO ₂ etc. in the exhaust gas. Therefore, nitrogen oxides composed of NO _{2 and the} like in the exhaust gas can be effectively reduced without using an expensive ozonizer or the like. Therefore, even when exhaust gas containing a very high concentration of nitrogen oxide is discharged from the processing apparatus 1 while preventing the manufacturing cost of the exhaust gas purification apparatus 50 from becoming high, the nitrogen oxide in the exhaust gas is efficiently used. There is an advantage that it can be discharged to the outside in a well reduced and detoxified state.

Further, as shown in the present embodiment, the reducing gas composed of hydrogen gas (H ₂ ) supplied from the reducing gas supply unit 53 is converted into plasma and reacted with nitrogen oxide (NOx) in the exhaust gas. In the exhaust gas purification apparatus configured to reduce NO ₂ or the like in the exhaust gas, when the ammonia filter 54 that adsorbs ammonia (NH ₃ ) generated by the reduction reaction is provided, There is an advantage that NO ₂ or the like can be effectively reduced and rendered harmless, and ammonia generated by this reduction reaction can be reliably prevented from being discharged to the outside.

  As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to this, For example, the modified embodiment of the following (1)-(6) can be taken.

  (1) In the said embodiment, the exhaust gas purification apparatus 50 which concerns on this invention showed the example applied to the processing apparatus 1 for performing a sterilization process. In addition to these, the present invention can also be applied to uses such as surface cleaning, modification, etching, thin film formation and removal of substrates and the like.

  (2) In the above-described embodiment, an example in which the sterilization process is performed in a state where the inside of the main chamber 11 is decompressed has been described. However, the sterilization process may be performed at normal pressure.

(3) In the above embodiment, an example in which two chambers, the main chamber 11 and the sub chamber 12, are used has been described. Omitted subchambers 12, from such a bomb NO ₂ gas is sealed, may be supplied to NO ₂ gas into the main chamber 11.

  (4) In the above-described embodiment, an example in which the main chamber 11 and the sub-chamber 12 are provided at 1: 1 is shown. Instead of this, a configuration may be adopted in which sterilization gas can be supplied from one sub-chamber 12 to a plurality of main chambers 11. Conversely, a configuration may be adopted in which sterilization gas is supplied from a plurality of subchambers 12 to one main chamber 11. In this case, different types of sterilizing gas may be supplied from each sub-chamber 12 to the main chamber 11.

  (5) In the above embodiment, after the exhaust gas is purified by reducing nitrogen oxide in the exhaust gas from the main chamber 11 of the processing apparatus 1 by the plasma reaction part (plasma nozzle 31), the fourth pump P4 is operated. The example which comprised so that it might discharge | emit immediately via was demonstrated. Instead, a reflux pipe for refluxing the exhaust gas purified in the plasma reaction unit to the upstream part of the plasma reaction unit is provided, for example, according to the output signal of the concentration sensor provided in the downstream part of the plasma reaction unit You may make it repeat the reduction | restoration purification process by the said plasma reaction part until it is confirmed that the NOx density | concentration in waste gas fell below the predetermined value.

(6) After reducing gas containing hydrogen gas (H ₂ ) supplied from the reducing gas tank 531 of the reducing gas supply unit 53 is converted into plasma by a plasma reaction unit including a plasma nozzle 31 provided in the circulation system 30. Instead of the embodiment configured to react with nitrogen oxides (NOx) in the exhaust gas derived from the main chamber 11 of the processing apparatus 1, plasma having a plasma nozzle or the like separate from that for the circulation system 30 is used. It is good also as a structure which provided the reaction part as an exclusive article of the exhaust gas purification apparatus 50. FIG. However, as shown in the above embodiment, the plasma nozzle 31 has a function as a plasma generation unit for the circulation system 30 that generates sterilizing nitrogen oxides, and a function as a plasma reaction unit for the exhaust gas purification device 50. In the case where the structure is also provided, there is an advantage that the structure of the apparatus can be effectively simplified and downsized.

DESCRIPTION OF SYMBOLS 1 Processing apparatus 11 1st chamber (processing part)
12 Second chamber (reservoir)
31 Plasma nozzle (plasma reaction part)
50 Exhaust gas purification device 53 Reducing gas supply unit 54 Ammonia filter

Claims (3)

An exhaust gas purifying device for purifying exhaust gas of a processing device that performs a predetermined treatment using a gas containing nitrogen oxide,
A reducing gas supply unit for supplying the reducing gas;
A plasma reaction unit that converts the reducing gas supplied from the reducing gas supply unit into plasma and reacts with nitrogen oxide in the exhaust gas derived from the processing apparatus to reduce nitrogen oxide and render it harmless; An exhaust gas purifying apparatus comprising: The plasma reaction unit converts the reducing gas composed of hydrogen gas supplied from the reducing gas supply unit into plasma, and reduces nitrogen oxides by reacting with nitrogen oxides in the exhaust gas,
The exhaust gas purification apparatus according to claim 1, further comprising an ammonia filter that adsorbs ammonia generated by the reduction reaction. The processing apparatus includes a processing unit that sterilizes the processing object by reacting the processing object with nitrogen dioxide, a storage unit having a sealed space into which air is introduced, and air in the storage unit is converted into plasma to generate nitrogen. With a plasma generator to produce oxide,
The exhaust gas purification apparatus according to claim 1 or 2, wherein the plasma generation part is used as a plasma reaction part for exhaust gas purification.

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