JP2006273677A - Nitrogen monoxide (no) generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an NO generating device where nitrogen monoxide can be stably generated from a harmless raw material such as air or a nitrogen-oxygen gaseous mixture without causing remarkable electromagnetic noise and without causing remarkable electrolytic corrosion in electrodes as brought about in arc discharge. <P>SOLUTION: The device is provided with an air uptake port 1; a dryer 2; a pump 3; a discharge reaction vessel 4; a pulse power source 5; an NO<SB>2</SB>removing apparatus 6; an NO measuring instrument 7; and a pure NO takeoff port 8, and, by applying prescribed voltage between electrodes in the discharge reaction vessel 4, corona discharge is caused. In the device, nitrogen monoxide is stably and efficiently generated by the corona discharge without generating remarkable electrolytic corrosion of the electrodes, electromagnetic noise or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a NO generator for producing nitric oxide used for medical purposes and other industrial purposes.

  In recent years, nitric oxide (NO) inhalation therapy has attracted attention as a new treatment method for respiratory diseases. In recent years, it has been discovered that nitric oxide has an action as an information transmitting substance and an action of locally expanding blood vessels. Based on this discovery, it has been found that nitric oxide inhalation therapy can be used for pulmonary hypertension, acute respiratory failure, asthma and other respiratory diseases. For example, when NO gas is inhaled by a patient with pulmonary hypertension, blood vessels on the alveolar surface dilate and the oxygen concentration in the blood increases, thereby reducing or improving pulmonary hypertension. Such nitric oxide inhalation therapy is clinically extremely safe and effective without the risk of blood pressure reduction caused by dilating the whole body blood vessels such as conventional drugs with vasodilatory effects. Expected as a therapy.

  Initially, as a method of supplying nitric oxide used for inhalation therapy, it is common to decompress the nitric oxide gas stored in the high-pressure gas container and mix it with the supply dilution gas, and let the patient inhale this mixed gas Met. However, nitric oxide gas is generally unstable and may be transformed into harmful nitrogen dioxide while stored in a high-pressure gas container. Therefore, a method has been adopted in which a moderately diluted mixed gas is stored in a high-pressure gas container and taken out from the high-pressure gas container as necessary.

  However, even in the method of stably storing nitric oxide gas in the high-pressure gas container, a large amount of nitrogen monoxide gas from the high-pressure gas container to the atmosphere due to the high-pressure gas container falling or its mouth being damaged. There is also a risk of accidents such as being released into the environment. In addition, nitric oxide released in such an accident may be instantaneously combined with oxygen in the atmosphere to form a large amount of toxic nitrogen dioxide.

  In addition, since the high-pressure gas container has a considerable size, carrying in and handling in case of emergency becomes extremely complicated, and there is also a concern that it may lead to a decrease in quality of life (QOL) of inhaled patients. Is done. This was an obstacle to the spread of nitric oxide inhalation therapy.

Therefore, as a supply method other than the method of supplying nitrogen monoxide from a high-pressure gas container, a method based on an oxidation reaction of ammonia (NH ₃ ) using high temperature platinum as a catalyst or a method based on a reaction between copper and dilute nitric acid (HNO ₃ ) Such a production method using a chemical reaction and a production method using an ionization phenomenon associated with arc discharge in air have been proposed (Patent Documents 1 to 4).
JP 2004-167284 A JP 2004-65636 A JP 2000-102616 A Japanese National Patent Publication No. 7-505073

  However, in the production method using a chemical reaction, ammonia or dilute nitric acid itself, which is a raw material for nitric oxide, is toxic, so that it is practically undesirable to use it in a medical field.

  In addition, arc discharge generally requires a large current, and it is obvious from the welding method that welding is performed by melting the welding rod with the large energy of the arc discharge. The method inevitably involves electrode erosion (electric corrosion) due to arc energy. There is a problem that impurities due to such electric corrosion are mixed, and a problem that the life of the electrode is short.

  Further, in the method of generating nitric oxide using arc discharge, there is a problem that the concentration of nitric oxide generated tends to become unstable due to correction of anxiety of arc discharge.

  Furthermore, as one of the medical systems in which significant electromagnetic noise is generated due to a large current for causing arc discharge, which causes a malfunction in surrounding medical devices in clinical practice. There was a fatal problem when using it.

  The present invention has been made in order to solve such a problem, and the object thereof is to produce air or a nitrogen / oxygen mixed gas without causing significant electromagnetic noise such as arc discharge and without causing electrolytic corrosion on the electrode. An object of the present invention is to provide a NO generator capable of stably generating nitric oxide from such a harmless raw material.

  The NO generator of the present invention includes a discharge reaction vessel having a pair of discharge electrodes therein, a raw material supply means for supplying a raw material gas containing nitrogen and oxygen in the discharge reaction vessel, and applying a predetermined discharge voltage to the discharge electrodes And NO generating means for generating nitric oxide (NO) by generating corona discharge in the discharge reaction vessel, and NO extracting means for taking out the generated nitric oxide.

  In this NO generator, nitric oxide is generated from a gas containing nitrogen and oxygen by corona discharge. This corona discharge does not cause significant electromagnetic noise as in arc discharge, and does not cause significant galvanic corrosion on the electrode as in arc discharge.

  Here, the discharge electrode may be a coaxial cylindrical electrode having a different diameter, or a flat electrode facing the needle tip of the needle electrode and the needle tip of the needle electrode, or at least of the needle electrode and the needle electrode. Any one of the cylindrical electrodes arranged so as to surround the needle tip apart can be used.

  In addition, a voltage applicator for corona discharge that applies a DC voltage of 5 kV or less or a pulse voltage of 10 μV or less and a time width of 1 μs or less to the two electrodes is provided with a distance between the two discharge electrodes of 10 mm or less. Thus, nitric oxide may be generated more efficiently. Here, it goes without saying that the lower limit value of the DC voltage or pulse voltage is the lowest voltage value at which corona discharge can occur.

  In addition to having a plurality of needle-like electrodes arranged as one pole, and having one flat electrode spaced apart from the tips of the plurality of needle-like electrodes as another pole, Further, nitric oxide may be generated more efficiently.

  In addition, the raw material gas supply means may be configured to include a dryer, and after the raw material gas is dried, the raw material gas may be supplied to the discharge reaction vessel, whereby nitrogen monoxide can be generated more efficiently.

  In addition, the pressure of the raw material gas supplied to the discharge reaction vessel is preferably set to a value within the range of atmospheric pressure to 10 atmospheric pressure, thereby efficiently generating nitric oxide.

  In addition, a NO measuring device for measuring the amount or generation rate of nitric oxide generated in the discharge reaction vessel is provided, and the discharge electrode is supplied to the discharge electrode based on the amount or generation rate of nitric oxide measured by the NO measuring device. A feedback control system that controls the applied voltage as an operation amount may be provided. With such a configuration, the amount or generation rate of nitric oxide generated in the discharge reaction vessel can be controlled, and the amount or generation rate of nitric oxide can be stabilized.

Moreover, if a nitrogen oxide remover is provided to remove nitrogen oxides NO _x (x ≧ 2), nitrogen oxides harmful to the human body are removed, and pure nitrogen monoxide is generated. Can do.

  According to the NO generator of the present invention, since corona discharge is used as the means for generating nitric oxide, it does not cause significant electromagnetic noise such as arc discharge, and without shortening the life of the electrode, It becomes possible to stably generate nitric oxide for a long period from harmless raw materials such as air or nitrogen / oxygen mixed gas.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows the configuration of the main part of an NO generator according to an embodiment of the present invention. FIG. 2 is an enlarged view of a part of two electrodes used therein.

This NO generator comprises an air inlet 1, a dryer 2, a pump 3, a discharge reaction vessel 4, a pulse power power source 5, a NO ₂ removal device 6, a NO measuring device 7 and a pure NO outlet 8. Nitric oxide is generated by corona discharge. Here, in FIG. 1, the flow of air and other generated gas is indicated by a solid line, and the flow of information or current is indicated by a broken line.

  The air intake 1 is for taking in air, which is a raw material of nitric oxide, from the outside of this NO generator. For example, the air intake 1 is formed in a funnel shape and effectively collects and sucks ambient air. Is set to be able to.

  The dryer 2 dries the air taken in from the outside through the air intake 1 and sends it to the pump 3. The air dried by the dryer 2 is likely to cause corona discharge in a discharge reaction vessel 4 to be described later and easily ionizes nitrogen and oxygen gas atoms. As a result, NO generation efficiency is further improved. It will be a thing.

  The pump 3 is an NO source gas supply device for supplying dry air to the discharge reaction vessel 4 at a predetermined pressure value in the range of atmospheric pressure to 10 atmospheres. The specific pressure value is a value that can effectively generate nitric oxide by corona discharge corresponding to the conditions other than the pressure of dry air, such as interelectrode voltage, voltage pulse frequency, desired generation rate, etc. It is set appropriately. The raw material gas supply means of the present invention is configured including the air intake port 1, the dryer 2 and the pump 3.

  The discharge reaction vessel 4 has two discharge electrodes spaced apart from each other, and a predetermined discharge voltage is applied between the electrodes to cause a corona discharge. Nitrogen monoxide is generated along with the corona discharge. Is to be generated. The discharge electrode for generating the corona discharge can have a structure as illustrated in FIGS.

  That is, as shown in FIG. 2, the discharge electrodes are two coaxial cylindrical electrodes 21 and 22 having different diameters, and a predetermined voltage is applied between the facing surfaces of the electrodes 21 and 22. An electric field is generated to generate a corona discharge that can effectively generate nitric oxide.

  Alternatively, as shown in FIG. 3, a needle electrode 31 is provided as one electrode, and a flat electrode 33 facing the needle tip 32 of the needle electrode 31 with a predetermined gap is provided. Thus, corona discharge may be generated by an electric field that is concentrated around the tip 32 of the needle electrode 31.

  Alternatively, as shown in FIG. 4, the needle-like electrode 31 and the cylindrical electrode 23 arranged so as to surround and surround at least the tip 32 of the needle-like electrode 31 are provided. Corona discharge may be generated by an electric field that is concentrated around the tip 32 of the electrode 31.

  Alternatively, as shown in FIG. 5, a large number of needle-like electrodes 31 arranged in a row are provided as one pole, and one of the many needle-like electrodes 31 provided separately from the tip 32 thereof. You may make it have the flat electrode 33 as another pole. Corona discharge capable of generating nitric oxide is generated in a large amount in proportion to the number of needle-like electrodes 31 by simple calculation due to the electric field generated around the tips 32 of the many needle-like electrodes 31. Thereby making it possible to effectively produce a larger amount of nitric oxide.

  Here, although depending on the voltage applied by the power pulse power supply 5, in the case of voltage setting as described later, corona discharge is realized more effectively and stably, and nitric oxide is generated more effectively. In order to achieve this, it is desirable that the distance between the two spaced apart electrodes be 10 mm or less. Needless to say, the lower limit value of the distance is a distance at which corona discharge can be stably continued without causing all insulation breakdown of air between the electrodes.

  The pulse power source 5 is for outputting a voltage for generating corona discharge and applying it to the electrodes in the discharge reaction vessel 4. For example, an on-board type pulse power source can be used. The pulse power source 5 is configured so that a DC voltage of 5 kV or less, or a pulse voltage of 10 μV or less and a time width of 1 μs or less is applied to the two electrodes for the above-described electrode setting. It is desirable to set. The NO generating means of the present invention is configured including the pulse power source 5.

The NO ₂ removal device 6 may generate nitrogen dioxide (NO ₂ ) along with carbon monoxide (NO 2) when carbon monoxide (NO) is generated by corona discharge in the discharge reaction vessel 4. A nitrogen oxide remover for removing nitrogen. The configuration and function of the NO ₂ removal device 6 may be the same as that of a general nitrogen dioxide removal device.

  The NO measuring device (NO sensor) 7 measures the production amount (generation rate) of nitric oxide produced in the discharge reaction vessel 4 per unit time.

The pure NO outlet 8 as the NO extracting means is an outlet for taking out nitrogen monoxide, which is generated in the discharge reaction vessel 4 and whose nitrogen dioxide has been removed by the NO ₂ removal device 6 and whose purity has been increased, to the outside. is there. In this pure NO outlet 8, when the concentration of nitric oxide produced in the discharge reaction vessel 4 is high, it is diluted to an appropriate concentration by mixing with air and then taken out to the outside. Good.

  Here, the NO generating device includes a feedback control system that controls the output of the pulse power power source 5 as an operation amount based on the generation rate of nitric oxide measured by the NO measuring device 7, and thereby discharge reaction. The production rate of nitric oxide produced in the container 4 is controlled. By such a feedback control system, it becomes possible to continue the production of nitric oxide stably and efficiently at a predetermined production rate.

  Such a NO generator according to the present embodiment does not require a gas cylinder as in the conventional nitric oxide supply system, and is extremely small and lightweight. Moreover, since the raw material of nitric oxide is air, as long as there is a power source such as a household power source or a battery for generating corona discharge, nitric oxide can be used in any place where air is present. It is possible to generate.

In addition to the dry air as in the above embodiment, a nitrogen / oxygen mixed gas may be used as the source gas. Further, in addition to NO ₂ , a NO _x removal device may be provided in order to remove nitrogen oxide (NO _x ; x ≧ 2) that may be generated accompanying the generation of NO. .

  Next, the operation and effect of this NO generator will be described.

  The air sucked from the air intake 1 is dried by the dryer 2 so that corona discharge is likely to occur. Then, it is compressed by the pump 3 to a pressure value in the range of, for example, atmospheric pressure or more to 10 atmospheres or less, and sent to the discharge reaction vessel 4.

  In the discharge reaction vessel 4, a corona discharge is generated by applying a pulse voltage of, for example, a voltage of 3 kV and a frequency of 1 μs from the pulse power source 5 to the two electrodes. Nitric oxide is generated from the dry air with the corona discharge.

  In this corona discharge, electrode erosion (electric corrosion) like arc discharge hardly occurs, and the discharge is stable, so the metal component of such eroded electrode is mixed into the extracted nitric oxide. There is little to do. Therefore, it is possible to stably supply high-purity nitric oxide that does not contain metal components of the electrode.

  In addition, this corona discharge can be generated with a very small current compared to arc discharge, and since the discharge stability is good, it generates nitric oxide with little noticeable electromagnetic noise. Can do. In addition, the power supply system such as the pulse power supply 5 can be made extremely small and simple, such as a small current inverter AC power source combining a battery and an onboard AC generation circuit.

The nitric oxide produced in the discharge reaction vessel 4 has its purity increased by removing NO ₂ through the NO ₂ removal device 6 and taken out from the pure NO outlet 8 to the outside.

  Thus, the NO generator of the present embodiment does not require a gas cylinder as in the conventional nitric oxide supply system, is extremely small and lightweight, and the source of nitric oxide is air, so corona discharge is not generated. Nitric oxide can be generated anywhere and can be easily transported as long as there is a power source, such as a household power source or a battery, to generate it. Therefore, this NO generator can be transported anywhere and can generate nitric oxide anywhere.

  Further, since the corona discharge generated with a small current is used, nitric oxide can be stably generated with little noticeable electromagnetic noise. In addition, since the feedback control system is provided to control the production rate of nitric oxide, more stable production of nitric oxide is possible. In addition, the power supply system such as the pulse power supply 5 can be made extremely small and simple, such as a small current inverter AC power source that is a combination of a battery and an on-board AC generation circuit.

  The NO generating apparatus of the present invention is for safely and stably generating nitric oxide gas used for nitric oxide inhalation therapy or the like from air or a nitrogen / oxygen mixed gas without causing significant electromagnetic noise or the like. It can be used as a small clinical NO generator that can be transported. In addition, it can also be used in various ways as an industrial NO generator for generating nitrogen monoxide from air or nitrogen / oxygen mixed gas stably at low cost.

It is a block diagram showing typically the composition of the principal part of the NO generating device concerning one embodiment of the present invention. It is the perspective view which expanded and showed partially extracted two electrodes used for the NO generator of FIG. It is a figure showing an example of an electrode structure. It is a figure showing the other example of an electrode structure. It is a figure showing the further another example of an electrode structure.

Explanation of symbols

1 ... air inlet, 2 ... dryer, 3 ... pump, 4 ... discharge reaction vessel, 5 ... Pulsed Power, 6 ... NO ₂ removal device, 7 ... NO instrument, 8 ... pure NO outlet, 21, 22 ... Electrode, 31 ... Needle electrode, 33 ... Flat plate electrode.

Claims (8)

A discharge reaction vessel having a pair of discharge electrodes therein;
Raw material supply means for supplying a raw material gas containing nitrogen and oxygen into the discharge reaction vessel;
NO generating means for generating nitric oxide (NO) by applying a predetermined discharge voltage to the discharge electrode and generating corona discharge in the discharge reaction vessel;
An NO generator comprising: NO extraction means for extracting the generated nitric oxide. As the discharge electrode, a pair of coaxial cylindrical electrodes having different diameters, or a flat electrode facing the tip of the needle electrode and the needle of the needle electrode, or at least a needle of the needle electrode and the needle electrode 2. The NO generator according to claim 1, comprising at least one set of cylindrical electrodes arranged so as to surround the front end of the first electrode. The distance between the two discharge electrodes is 10 mm or less, and the discharge voltage is a DC voltage of 5 kV or less or a pulse voltage having a time width of 10 μV or less and 1 μs or less. The NO generator according to 2. A plurality of needle-like electrodes arranged in a row are provided as one discharge electrode, and one plate-like electrode provided apart from the needle tips of the plurality of needle-like electrodes is provided as the other discharge electrode. The NO generator according to claim 1. The NO generating apparatus according to any one of claims 1 to 4, wherein the source gas supply means includes a dryer and supplies the discharge gas to the discharge reaction vessel after drying the source gas. 6. The pressure according to claim 1, wherein the pressure of the source gas supplied by the NO source gas supply means is set to a value in the range of atmospheric pressure to 10 atmospheric pressure. NO generator. A NO measuring device for measuring the amount or generation rate of nitric oxide produced in the discharge reaction vessel is provided, and the voltage applied to the discharge electrode is operated based on the measurement result measured by the NO measuring device. The NO generating device according to any one of claims 1 to 6, further comprising a feedback control system that controls the amount, and controlling the amount or generation rate of the generated nitric oxide. The NO generator according to any one of claims 1 to 7, further comprising a nitrogen oxide remover, and removing nitrogen oxide NO _x (x ≧ 2).

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