JP2006208397A - Method and device for measuring critical combustion supporting gas concentration in mist explosion - Google Patents
Method and device for measuring critical combustion supporting gas concentration in mist explosion Download PDFInfo
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本発明は、ミスト爆発における限界支燃性ガス濃度の測定方法およびその装置に関する。 The present invention relates to a method and an apparatus for measuring a limit combustion-supporting gas concentration in a mist explosion.
従来より、可燃性液体を安全に取り扱う基準の一つとして、可燃性液体の引火点と導電率が採用されている。 Conventionally, the flash point and conductivity of flammable liquids have been adopted as one of the criteria for safely handling flammable liquids.
引火点とは、可燃性液体が支燃性ガス雰囲気中でその液体表面の近くに引火するのに十分な濃度の蒸気を生じる最低温度であり、引火点を測定する手段としては、ＡＳＴＭ，ＩＳＯやＪＩＳによって承認された多数の装置や測定法が知られている。しかし、可燃性液体は気相において、常時、蒸気で存在しているものではなく、ミスト状態で存在する場合がある。かかる可燃性液体のミストの燃焼は、引火点との関連性が低く、引火点以下においても、静電気放電等の着火源の存在によって燃焼を生じるミスト爆発が起きる。したがって、可燃性液体を取り扱う場合には、引火点のみを考慮していては不十分であり、ミスト爆発が起こらない条件を設定する必要がある。 The flash point is the lowest temperature at which a flammable liquid produces a vapor of sufficient concentration to ignite near the liquid surface in a flammable gas atmosphere. As a means for measuring the flash point, ASTM, ISO Many devices and measurement methods approved by JIS and JIS are known. However, the flammable liquid is not always present in vapor in the gas phase, but may exist in a mist state. Such flammable liquid mist combustion has a low relevance to the flash point, and even below the flash point, a mist explosion that causes combustion occurs due to the presence of an ignition source such as electrostatic discharge. Therefore, when handling a flammable liquid, it is not sufficient to consider only the flash point, and it is necessary to set conditions under which mist explosion does not occur.
また、導電率とは物質の静電気の帯易さや電荷の逃げ易さを示す指標となる値であり、導電率が１０-8Ｓ／ｍ以上の物質は一般に非帯電性に分類され、着火爆発を防止する為の静電気対策が不要とされる。しかし、帯電したミストの電荷の減衰は、ミストが存在する媒体である気体の導電率によって左右される。空気等の気体は一般に導電率が小さく、絶縁性であるため、導電率が１０-8Ｓ／ｍ以上の可燃性液体がミストとして存在する場合には、当該可燃性液体の導電率が１０-8Ｓ／ｍ以上であっても、ミスト爆発が起こらない条件を設定する必要がある。 Conductivity is a value that can be used as an index to indicate the ease of static electricity and the escape of electric charge. Substances with an electrical conductivity of 10 -8 S / m or more are generally classified as non-charged and ignite and explode. To prevent static electricity. However, the charge attenuation of the charged mist depends on the conductivity of the gas that is the medium in which the mist is present. Since gas such as air generally has low conductivity and is insulative, when a flammable liquid having a conductivity of 10 −8 S / m or more exists as mist, the conductivity of the flammable liquid is 10 −. Even if it is 8 S / m or more, it is necessary to set conditions under which mist explosion does not occur.
ミスト爆発の指標としては、ミスト爆発を起こさないミストの下限界濃度を測定することが知られており、当該下限界濃度を測定する装置としては、たとえば、第２８回安全工学研究発表会講演予稿集第３５〜第３８頁に記載のものが知られている。当該予稿集に記載の装置は、所定容積の燃焼筒内に、被検可燃性液体をミスト状態で噴霧した後に燃焼筒内のミスト重量を測定することによりミスト濃度を割り出すとともに、当該ミスト濃度における点火によるミスト爆発の有無を確認することにより、ミスト爆発におけるミストの下限界濃度を測定している。しかし、当該予稿集に記載の装置では、燃焼筒内のミスト重量の測定にあたって、ミスト状態を呈しなくなって燃焼筒内壁を付着・流下する被検可燃性液体の重量もミスト重量として加えられているため、ミストの下限界濃度が実際よりも高く認識され、ミストの下限界濃度が正確に測定されているとはいえなかった。このように誤って高く認識された、ミストの下限界濃度では、当該下限界濃度以下でもミスト爆発が起こりうる。 As an indicator of mist explosion, it is known to measure the lower limit concentration of mist that does not cause mist explosion, and as a device for measuring the lower limit concentration, for example, the 28th Safety Engineering Research Presentation Lecture Proposal Those described in pages 35 to 38 of the collection are known. The apparatus described in the preliminary report is to determine the mist concentration by measuring the mist weight in the combustion cylinder after spraying the combustible liquid to be tested in the mist state into the combustion cylinder having a predetermined volume, and at the mist concentration. By checking the presence or absence of a mist explosion due to ignition, the lower limit concentration of mist in a mist explosion is measured. However, in the apparatus described in the proceedings, when measuring the mist weight in the combustion cylinder, the weight of the flammable liquid to be detected that does not exhibit the mist state and adheres and flows down the inner wall of the combustion cylinder is also added as the mist weight. Therefore, the lower limit concentration of mist was recognized to be higher than actual, and the lower limit concentration of mist was not accurately measured. Thus, at the lower limit concentration of mist, which is mistakenly recognized as high, a mist explosion can occur even below the lower limit concentration.
ミスト爆発には支燃性ガスの存在が条件となっていることから、ミスト爆発を起こさない限界支燃性ガス濃度を測定することが有効と考えられるが、当該限界支燃性ガス濃度を測定する方法、装置は知られていない。 Since the presence of a flammable gas is a condition for a mist explosion, it is considered effective to measure the limit flammable gas concentration that does not cause a mist explosion. There is no known method or device to do this.
そこで、本発明の目的は、ミスト爆発における限界支燃性ガス濃度を測定する方法および装置を提供することにある。 Accordingly, an object of the present invention is to provide a method and an apparatus for measuring the limit combustion-supporting gas concentration in a mist explosion.
本発明者らは、前記課題を解決すべく鋭意検討を重ねた結果、以下に示す方法、装置により前記目的を達成できることを見出し、本発明を完成するに到った。 As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the following method and apparatus, and have completed the present invention.
すなわち、本発明は、略密閉された燃焼筒内を、所定の支燃性ガス濃度に設定するとともに、被検可燃性液体をミスト状態で噴霧した後に、点火による爆発の有無を確認することによって、ミスト爆発における限界支燃性ガス濃度を測定する方法に関する。上記方法にしたがって、ミスト爆発における限界支燃性ガス濃度が測定され、被検可燃性液体に固有の限界支燃性ガス濃度を把握できる。 That is, the present invention sets the inside of a substantially sealed combustion cylinder to a predetermined combustion-supporting gas concentration, and after spraying the test combustible liquid in a mist state, confirms the presence or absence of an explosion due to ignition. The present invention relates to a method for measuring the limit combustion-supporting gas concentration in a mist explosion. According to the above method, the limit flammable gas concentration in the mist explosion is measured, and the limit flammable gas concentration unique to the test flammable liquid can be grasped.
上記ミスト爆発における限界支燃性ガス濃度を測定する方法に用いる、可燃性液体のミスト爆発における限界支燃性ガス濃度測定装置としては、たとえば、可燃性液体のミスト爆発における限界支燃性ガス濃度測定装置であって、略密閉された燃焼筒を有し、当該燃焼筒内には、支燃性ガス導入管、支燃性ガス濃度計、被検可燃性液体のミスト発生装置およびミスト爆発させるための着火装置を有するものが用いられる。かかる限界支燃性ガス濃度測定装置により、所定支燃性ガス濃度における各種条件下のミスト爆発を繰り返すことにより、限界支燃性ガス濃度が容易に求められる。 The limit flammable gas concentration measuring device in the mist explosion of the flammable liquid used in the method for measuring the limit flammable gas concentration in the mist explosion is, for example, the limit flammable gas concentration in the mist explosion of the flammable liquid. A measuring device having a substantially sealed combustion cylinder, and a combustion-supporting gas introduction pipe, a combustion-supporting gas concentration meter, a mist generating device for a combustible liquid to be tested, and a mist explosion The one having an ignition device is used. By such a limit combustion-supporting gas concentration measuring device, the limit combustion-supporting gas concentration can be easily obtained by repeating mist explosion under various conditions at a predetermined combustion-supporting gas concentration.
また、限界支燃性ガス濃度測定装置において、前記ミスト発生装置は、気液混合物を噴霧させる仕組みからなるものが好ましい。ミスト発生装置は、ミストを発生させうるものであれば特に制限されるものではないが、ミスト爆発はミストの平均粒径が５０μｍよりも小さな粒径で起きやすい傾向があることから、５０μｍ以下の平均粒径を形成させることが可能な、気液混合物を噴霧させる仕組みからなるノズルの適用が好ましい。 In the limit combustion-supporting gas concentration measuring device, the mist generating device preferably has a mechanism for spraying a gas-liquid mixture. The mist generating device is not particularly limited as long as it can generate mist, but mist explosion tends to occur when the average particle size of mist is smaller than 50 μm. It is preferable to apply a nozzle having a mechanism for spraying a gas-liquid mixture capable of forming an average particle diameter.
前記燃焼筒は、燃焼筒の開口部を薄膜で覆うことにより略密閉とするのが好ましい。薄膜は、外部からの空気が混入するのを防止でき、一方、燃焼筒内からはある程度通気可能なため、燃焼筒内の支燃性ガス濃度を均一に安定化できる。薄膜はミスト爆発における爆風によって吹き飛ばされることにより、燃焼筒そのものが破損することを防ぐことができ安全性が向上する。また、前記開口部は、薄膜でシールされた網状物で覆うのがより好ましい。網状物が、フレームアレスタの役割をして、ミスト爆発により生じる火炎が燃焼筒外にまで及ぶことを防ぐ。 The combustion cylinder is preferably substantially sealed by covering the opening of the combustion cylinder with a thin film. The thin film can prevent air from the outside from being mixed in. On the other hand, since it can be ventilated to some extent from the inside of the combustion cylinder, the concentration of the combustion-supporting gas in the combustion cylinder can be stabilized uniformly. The thin film is blown away by a blast in a mist explosion, so that the combustion cylinder itself can be prevented from being damaged, and safety is improved. The opening is more preferably covered with a net-like material sealed with a thin film. The reticulated material acts as a flame arrester to prevent the flame generated by the mist explosion from reaching the outside of the combustion cylinder.
可燃性液体を、当該可燃性液体の引火点未満の温度で取り扱う際に、当該可燃性液体を、当該可燃性液体に係わる、ミスト爆発における限界支燃性ガス濃度以下に調整することによって、可燃性液体のミスト爆発を制御することができる。 When handling a flammable liquid at a temperature below the flash point of the flammable liquid, the flammable liquid is adjusted to be less than the limit flammable gas concentration in a mist explosion related to the flammable liquid. The mist explosion of the ionic liquid can be controlled.
可燃性液体の取り扱いにおいて、限界支燃性ガス濃度による管理、制御を行うことにより、引火点のみでは予期できなかった、ミスト爆発の制御が可能になる。さらには、前記ミスト爆発を制御する方法は、可燃性液体の導電率が１０-8Ｓ／ｍ以上の場合において有用である。導電率が１０-8Ｓ／ｍ以上の可燃性液体は、通常、静電気爆発を生起し難いが、ミスト状態で空気等の媒体中に存在する場合には、帯電して爆発に通じる場合があり、このような導電率を有する可燃性液体についても、限界支燃性ガス濃度による管理、制御を行うことにより、引火点のみでは予期出来なかった、ミスト爆発の制御が可能になる。 When handling flammable liquids, control and control based on the limit flammable gas concentration makes it possible to control mist explosions that could not be expected only by the flash point. Furthermore, the method for controlling the mist explosion is useful when the conductivity of the combustible liquid is 10 −8 S / m or more. Combustible liquids with electrical conductivity of 10 -8 S / m or more usually do not easily cause an electrostatic explosion. However, if they exist in a medium such as air in a mist state, they may be charged and lead to an explosion. By controlling and controlling the flammable liquid having such conductivity based on the limit flammable gas concentration, it becomes possible to control a mist explosion that could not be expected only by the flash point.
なお、ミスト爆発は、通常、引火点未満の温度で起きるため、限界支燃性ガス濃度の管理により、引火点を考慮することなく、可燃性液体の取り扱いを安全に行うことができる。 In addition, since mist explosion usually occurs at a temperature below the flash point, the control of the limit flammable gas can safely handle the flammable liquid without considering the flash point.
ミスト爆発における限界支燃性ガス濃度の測定は、前記方法、装置により求めたものを用いることにより、ミスト爆発の制御を、より正確になしえる。 The measurement of the critical combustion-supporting gas concentration in the mist explosion can control the mist explosion more accurately by using the value obtained by the above method and apparatus.
以下、本発明を図面を参照して説明する。 The present invention will be described below with reference to the drawings.
図１は、ミスト爆発におけるミストの限界支燃性ガス濃度測定装置に関するものであり、ミスト爆発させるための燃焼筒２１の材質は、耐熱性のものであれば特に制限されないが、運搬等の取り扱いの容易なプラスチック製のものが好ましく、特にポリ塩化ビニール、ポリメチルメタクリレート、ポリカーボネート等の透明樹脂が好ましい。燃焼筒２１は、略密閉となりうるものを用いる。略密閉とは、燃焼筒２１内の支燃性ガス濃度調整が可能な程度に気密性を保持した状態をいう。 FIG. 1 relates to an apparatus for measuring the limit flammable gas concentration of mist in a mist explosion. The material of the combustion cylinder 21 for causing mist explosion is not particularly limited as long as it is heat resistant, but handling such as transportation Are easily made of plastic, and transparent resins such as polyvinyl chloride, polymethyl methacrylate, and polycarbonate are particularly preferable. A combustion cylinder 21 that can be substantially sealed is used. The term “substantially sealed” refers to a state where the airtightness is maintained to such an extent that the concentration of the combustion-supporting gas in the combustion cylinder 21 can be adjusted.
図１は、燃焼筒２１の開口部を、網状物２２ａおよび２３で覆い、その外側から薄膜２２ｂおよび２４で覆って、燃焼筒２１内部を略密閉状態とすることにより、燃焼筒２１内の支燃性ガス濃度の制御を可能にしている。なお、燃焼筒２１の上部開口部２２は、薄膜２２ｂでシールされた網状物２２ａを用いている。支燃性ガスを含む気体をパージすることにより、燃焼筒２１が加圧状態になると薄膜の間隙から外部へ通気し、燃焼筒２１内の支燃性ガス濃度を一定に維持する。薄膜の材質としては、ポリ塩化ビニール、ポリエチレン、アルミ箔等が用いられる。薄膜２２ｂ、２４は、爆発により容易に破壊され、燃焼筒２１が破損するのを防ぎ、網状物２２ａ、２３は、火炎の伝播を遮断する。また、網状物２２ａ、２３としては、フレームアレスタに有効な金属素材、たとえば金網が好ましい。 In FIG. 1, the opening of the combustion cylinder 21 is covered with the reticulates 22a and 23 and covered with the thin films 22b and 24 from the outside to make the inside of the combustion cylinder 21 in a substantially sealed state. This makes it possible to control the concentration of flammable gas. The upper opening 22 of the combustion cylinder 21 uses a net 22a sealed with a thin film 22b. By purging the gas containing the combustion-supporting gas, when the combustion cylinder 21 is in a pressurized state, it is vented to the outside through the gap between the thin films, and the concentration of the combustion-supporting gas in the combustion cylinder 21 is kept constant. As the material of the thin film, polyvinyl chloride, polyethylene, aluminum foil or the like is used. The thin films 22b and 24 are easily broken by explosion to prevent the combustion cylinder 21 from being damaged, and the nets 22a and 23 block the propagation of the flame. Further, as the nets 22a and 23, a metal material effective for a frame arrester, for example, a wire net is preferable.
また、薄膜２４は、落下したミストが溜まりうるようにある程度余裕を持たせて底面部を覆うのが好ましい。なお、薄膜２４に落下したミストの量が多くなると、薄膜２４の剥脱が生じうるので、網状物２３を設ける場合には、底面部にミスト回収槽を設けるのが好ましい。回収槽は、燃焼筒２１の底部の壁面に沿って設けられる。被検可燃性液体は、燃焼筒２１内にミスト状態で噴霧されるが、ミストの一部は、燃焼筒２１の内壁に付着・流下して、回収槽に回収される。回収槽には、排出管を設けることにより、連続的に回収槽から排出することもできる。 Further, it is preferable that the thin film 24 covers the bottom surface part with some allowance so that the dropped mist can collect. If the amount of mist dropped on the thin film 24 is increased, the thin film 24 may be peeled off. Therefore, when the net 23 is provided, it is preferable to provide a mist collection tank on the bottom surface. The recovery tank is provided along the wall surface at the bottom of the combustion cylinder 21. The combustible liquid to be detected is sprayed in the mist state in the combustion cylinder 21, but a part of the mist adheres and flows down on the inner wall of the combustion cylinder 21 and is recovered in the recovery tank. The recovery tank can be continuously discharged from the recovery tank by providing a discharge pipe.
燃焼筒２１は、通常、高さ３００〜３０００ｍｍ程度、また断面形状は特に制限ないが、通常、円筒形のものが用いられ、直径１００〜１０００ｍｍ程度である。 The combustion cylinder 21 is usually about 300 to 3000 mm in height and the cross-sectional shape is not particularly limited, but a cylindrical one is usually used and has a diameter of about 100 to 1000 mm.
燃焼筒２１には、支燃性ガス導入管２５、不燃性ガス導入管２６が備えられている。燃焼筒２１は、支燃性ガス導入管２５から送られる支燃性ガスと、不燃性ガス導入管２６から送られる不燃性ガスによって、所定支燃性ガス濃度に置換される。なお、支燃性ガス導入管２５から送られる支燃性ガスは、酸素、塩素、酸化窒素等が用いられる。通常は、空気等が用いられる。不燃性ガス導入管２６から送られる不燃性ガスは、窒素、二酸化炭素、スチ−ム等が用いられる。通常は窒素等が用いられる。支燃性ガスと不燃性ガスを予め混合しておけばすれば不燃性ガス導入管２６は不要である。燃焼筒２１内の支燃性ガス濃度は支燃性ガス濃度計２７により常時測定する。 The combustion cylinder 21 is provided with a combustion-supporting gas introduction pipe 25 and an incombustible gas introduction pipe 26. The combustion cylinder 21 is replaced with a predetermined combustion-supporting gas concentration by the combustion-supporting gas sent from the combustion-supporting gas introduction tube 25 and the nonflammable gas sent from the non-combustion gas introduction tube 26. In addition, oxygen, chlorine, nitric oxide, etc. are used for the combustion support gas sent from the combustion support gas introducing pipe 25. Usually, air or the like is used. Nitrogen, carbon dioxide, steam or the like is used as the nonflammable gas sent from the nonflammable gas introduction pipe 26. Usually nitrogen or the like is used. If the combustion-supporting gas and the non-combustible gas are mixed in advance, the non-combustible gas introduction pipe 26 is unnecessary. The combustion-supporting gas concentration in the combustion cylinder 21 is constantly measured by a combustion-supporting gas concentration meter 27.
ミスト発生装置２８の設置位置は特に制限されないが、図１に示すように、上向きにミストを噴霧する場合は燃焼筒２１の下部中央に設けるのが、燃焼筒２１内のミスト状態がよく好ましいが、上部中央部にミスト発生装置２８を設けて下向きにミストを噴霧することもできる。ミスト発生装置２８としては、たとえば、たとえば、霧のいけうち社製の２流体ノズルＢＩＭ Ｋ６００７５やＢＩＭＫ６０１５等が用いられる。ミスト発生装置２８には、被検可燃性液体を導入するための液体導入管２９と支燃性ガス導入管３０が接続されている。液体導入管２９の液圧と支燃性ガス導入管３０の気圧を適宜に調整することにより、噴霧されるミスト濃度が調整される。 Although the installation position of the mist generating device 28 is not particularly limited, as shown in FIG. 1, when spraying mist upward, it is preferable that the mist state in the combustion cylinder 21 is provided in the lower center of the combustion cylinder 21. Alternatively, a mist generator 28 may be provided in the upper central portion to spray mist downward. As the mist generating device 28, for example, a two-fluid nozzle BIM K60075, BIMK 6015, or the like manufactured by Mist Ikeuchiuchi is used. Connected to the mist generator 28 are a liquid introduction pipe 29 and a combustion-supporting gas introduction pipe 30 for introducing the test combustible liquid. The mist concentration to be sprayed is adjusted by appropriately adjusting the liquid pressure of the liquid introduction pipe 29 and the atmospheric pressure of the combustion-supporting gas introduction pipe 30.
支燃性ガス導入管３０には通常、燃焼筒２１内の支燃性ガス濃度に調整されたガスが用いられる。なお、ミストを噴霧する前に支燃性ガス導入管３０を用いて所定濃度の支燃性ガスを送り込むことにより、燃焼筒２１中の支燃性ガス濃度を所定濃度に設定することもできる。この場合には、支燃性ガス導入管２５、不燃性ガス導入管２６は不要である。 For the combustion-supporting gas introduction pipe 30, a gas adjusted to the concentration of the combustion-supporting gas in the combustion cylinder 21 is usually used. It should be noted that the combustion-supporting gas concentration in the combustion cylinder 21 can be set to a predetermined concentration by feeding the combustion-supporting gas having a predetermined concentration using the combustion-supporting gas introduction pipe 30 before spraying mist. In this case, the combustion-supporting gas introduction pipe 25 and the non-combustible gas introduction pipe 26 are unnecessary.
ミスト爆発させるための着火装置３１の位置は特に制限されないが、図１に示すように、燃焼筒２１の高さの下から１／４〜３／４程度の位置とするのが好ましい。着火装置３１としては、たとえば、放電電極、ニクロム線溶断や白金線溶断等が用いられる。 Although the position of the ignition device 31 for causing the mist explosion is not particularly limited, as shown in FIG. 1, it is preferable to set the position to about ¼ to ¾ from the bottom of the height of the combustion cylinder 21. As the ignition device 31, for example, a discharge electrode, nichrome wire fusing, platinum wire fusing, or the like is used.
上記図１に示す限界支燃性ガス濃度測定装置を実際に操作するにあたっては、ます燃焼筒２１内を、支燃性ガス濃度計２７により測定しながら、たとえば、支燃性ガス導入管２5 から送られる空気と不燃性ガス導入管２６から送られる不燃性ガスによって、所定濃度に置換する。 In actual operation of the limit combustion-supporting gas concentration measuring apparatus shown in FIG. 1, while measuring the inside of the combustion cylinder 21 with the support-supporting gas concentration meter 27, for example, from the support-supporting gas introduction pipe 25 The air and the incombustible gas introduced from the incombustible gas introduction pipe 26 are replaced with a predetermined concentration.
次いで、液体導入管２９の液圧と支燃性ガス導入管３０の気圧を適宜に調整して、ミスト発生装置２８から被検可燃性液体を噴霧し、ミスト状態で燃焼筒２１内に噴霧させる。噴霧時間は、通常、１０〜６０秒程度が適当である。 Next, the liquid pressure of the liquid introduction pipe 29 and the atmospheric pressure of the combustion-supporting gas introduction pipe 30 are appropriately adjusted, and the combustible liquid to be tested is sprayed from the mist generating device 28 and sprayed into the combustion cylinder 21 in the mist state. . The spraying time is usually about 10 to 60 seconds.
次いで、着火装置３１により点火して、ミスト爆発の有無を確認する。爆発の有無の確認は、通常、目視で行うが、燃焼筒２１の内部に熱電対等を挿入して燃焼筒１内の温度上昇の有無により判断することもできる。なお、図１の装置では、燃焼筒２１の上面部および底面部に網状物網２２ａ、２３を用いているので、ミスト爆発により火炎が燃焼筒２１外に殆ど出ない。しかも、爆風によって網状物２２にシールされている薄膜２２ｂ、２４が破壊されるのみで燃焼筒２１は損傷しない。 Next, the ignition device 31 is ignited to check for the presence of a mist explosion. The confirmation of the presence or absence of an explosion is usually made visually, but it can also be determined by the presence or absence of a temperature rise in the combustion cylinder 1 by inserting a thermocouple or the like into the combustion cylinder 21. In the apparatus of FIG. 1, since the mesh nets 22 a and 23 are used for the upper surface portion and the bottom surface portion of the combustion cylinder 21, the flame hardly comes out of the combustion cylinder 21 due to the mist explosion. Moreover, the combustion cylinder 21 is not damaged by only destroying the thin films 22b, 24 sealed to the mesh 22 by the blast.
この操作を、所定の支燃性ガス濃度において、種々の条件でミスト爆発の有無の確認をする。ミスト爆発は、ミスト径が５０μｍ以下、通常は１０〜４０μｍ程度の場合に起こり易いため、少なくとも前記範囲内のミストの径のものを確認するのが好ましい。また支燃性ガス濃度を変更して繰り返し行うことにより、ミスト爆発する支燃性ガス濃度とミスト爆発しない支燃性ガス濃度を探って、最終的にミスト爆発の限界支燃性ガス濃度を見出す。ミストの限界支燃性ガス濃度は、測定条件の中で燃焼が伝播しない最高の支燃性ガス濃度とすることができる。 In this operation, the presence or absence of a mist explosion is confirmed under various conditions at a predetermined supporting gas concentration. Since mist explosion is likely to occur when the mist diameter is 50 μm or less, usually about 10 to 40 μm, it is preferable to check at least the mist diameter within the above range. In addition, by repeatedly changing the flammable gas concentration, the flammable gas concentration that causes mist explosion and the flammable gas concentration that does not explode mist are explored, and finally the limit flammable gas concentration of mist explosion is found. . The critical flammable gas concentration of the mist can be the highest flammable gas concentration at which combustion does not propagate among the measurement conditions.
このようにして可燃性液体のミスト爆発におけるミストの限界支燃性ガス濃度が正確に測定可能であり、可燃性液体を当該可燃性液体の引火点未満の温度で取り扱う際に、当該可燃性液体ミストの限界支燃性ガス濃度以下に調整することにより、可燃性液体のミスト爆発を制御でき、安全な操業が可能になる。ミストの限界支燃性ガス濃度の測定は、本発明の方法、装置、特に前記図１の装置によれば、正確な値を把握できる。 In this way, the limit flammable gas concentration of the mist in the mist explosion of the flammable liquid can be accurately measured, and when the flammable liquid is handled at a temperature below the flash point of the flammable liquid, the flammable liquid By adjusting the concentration below the limit flammable gas concentration of mist, mist explosion of flammable liquid can be controlled, and safe operation becomes possible. According to the method and apparatus of the present invention, particularly the apparatus shown in FIG.
可燃性液体の存在する系内における支燃性ガス濃度をミスト爆発が起きないように調整する手段は、たとえば、窒素、二酸化炭素、スチーム等の不燃焼性ガスにより支燃性ガス濃度を希釈化する方法等により可燃性液体の存在する系内の支燃性ガス濃度を下げる方法等があげられる。 The means to adjust the flammable gas concentration in the system where flammable liquid exists so that mist explosion does not occur, for example, dilute the flammable gas concentration with non-combustible gas such as nitrogen, carbon dioxide, steam, etc. For example, there is a method for reducing the concentration of the combustion-supporting gas in the system where the flammable liquid exists.
こうしたミスト爆発の制御にあたって、限界支燃性ガス濃度の調整は容易に行うことができる。 In controlling such a mist explosion, it is possible to easily adjust the limit combustible gas concentration.
実際の操業にあたっては、限界支燃性ガス濃度の前記限界値よりも、低いところで操業することにより、ミスト爆発を制御する。支燃性ガス濃度に関しては限界支燃性ガス濃度よりも６０％程度低い条件下で操業するのが好ましい。 In actual operation, the mist explosion is controlled by operating at a position lower than the limit value of the limit combustible gas concentration. It is preferable to operate under the condition that the supporting gas concentration is about 60% lower than the limiting supporting gas concentration.
なお、可燃性液体としては、ミスト爆発のおそれがあるであれば特に限定されず、たとえば、２−エチルヘキサノール、Ｎ−メチルピロリドン、エタノール等や、エタノール等を水等で希釈したもの等を例示できる。ミスト爆発のおそれがあるような操業としては、たとえば、前記可燃性液体を用いたベンチュリースクラバー、スプレー塔、スプレー洗浄設備等の取り扱い現場や製造現場等があげられる。 The flammable liquid is not particularly limited as long as there is a risk of mist explosion. Examples thereof include 2-ethylhexanol, N-methylpyrrolidone, ethanol, etc., ethanol diluted with water, etc. it can. Examples of operations that may cause a mist explosion include handling sites and manufacturing sites such as venturi scrubbers, spray towers, and spray cleaning equipment using the flammable liquid.
実施例１
ミストの限界支燃性ガス濃度測定の具体例として、図１のような装置を用いて、可燃性液体（２−エチルヘキサノール、引火点７３℃）の限界支燃性ガス濃度を測定した例を示す。燃焼筒２１の高さ２ｍ、直径０．６ｍ、平面形状の網状物２２ａ、２３、薄膜２２ｂ、２４を用い、表１に示すように支燃性ガス導入管２５から送られる空気、不燃性ガス導入管２６から送られる不燃性ガスによって、燃焼筒２１内を所定濃度に置換した。また、表１に示すように液体導入管２９の液圧と支燃性ガス導入管３０の気圧（所定支燃性ガス濃度）を変化させてミスト濃度を調整した。表１に酸素濃度、ミスト爆発の判定を示す。なお、ミスト爆発の有無の判定の項は、○：点火により火炎が目視で観測され燃焼筒２１内全体に燃焼が伝播、△：点火しても火炎は目視では観測できないが燃焼筒２１内に設置した熱電対等の温度上昇によって検知可能な弱い燃焼伝播、×：点火しても燃焼非伝播、を示す。その他、気温１８〜２１℃、湿度７２〜８１％、噴霧気体温度１６〜２２℃、噴霧液温度１６〜２０℃、噴霧時間４０秒の条件である。
Example 1
As a specific example of the measurement of the limit flammable gas concentration of mist, an example of measuring the limit flammable gas concentration of a flammable liquid (2-ethylhexanol, flash point 73 ° C.) using an apparatus as shown in FIG. Show. As shown in Table 1, air and non-combustible gas are used as shown in Table 1 by using the nets 22a, 23 and thin films 22b, 24 having a height of 2m, a diameter of 0.6m, and a planar shape of the combustion cylinder 21. The inside of the combustion cylinder 21 was replaced with a predetermined concentration by the nonflammable gas sent from the introduction pipe 26. Further, as shown in Table 1, the mist concentration was adjusted by changing the liquid pressure of the liquid introduction pipe 29 and the atmospheric pressure (predetermined combustion support gas concentration) of the combustion support gas introduction pipe 30. Table 1 shows the determination of oxygen concentration and mist explosion. It should be noted that the determination of the presence or absence of mist explosion is as follows: ○: flame is visually observed by ignition and combustion is propagated throughout the combustion cylinder 21; Δ: flame is not visually observed even after ignition, but is in the combustion cylinder 21 Weak combustion propagation that can be detected by temperature rise of installed thermocouples, etc., x: non-combustion after ignition. In addition, the temperature is 18 to 21 ° C., the humidity is 72 to 81%, the spray gas temperature is 16 to 22 ° C., the spray liquid temperature is 16 to 20 ° C., and the spray time is 40 seconds.
点火は同一噴霧圧力条件で最大６回実施し、１回でも燃焼が伝播すれば爆発すると判定し、１回も燃焼が伝播しない場合を爆発しないと判定した。 Ignition was performed a maximum of 6 times under the same spray pressure condition, and it was determined that explosion would occur if combustion was propagated even once, and a case where combustion was not propagated even once was determined not to be exploded.
表１から、２−エチルヘキサノールに関して、ミスト爆発の限界酸素は約１１％であることが認められる。 From Table 1, it can be seen that for 2-ethylhexanol, the limiting oxygen for mist explosion is about 11%.
２１：燃焼筒
２５：支燃性ガス導入管
２７：支燃性ガス濃度計
２８：ミスト発生装置
３１：着火装置
21: Combustion cylinder 25: Supporting gas introduction pipe 27: Supporting gas concentration meter 28: Mist generator 31: Ignition device
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| JP2010008135A (en) * | 2008-06-25 | 2010-01-14 | Gastec:Kk | Apparatus for explosion testing of combustible gas/vapor |
| CN102608161A (en) * | 2012-03-07 | 2012-07-25 | 北京理工大学 | Method for testing critical energy of detonation formed by direct initiation |
| CN112473068A (en) * | 2020-12-04 | 2021-03-12 | 中核建中核燃料元件有限公司 | High-activity material digestion device |
| CN117233210A (en) * | 2023-11-14 | 2023-12-15 | 山东科技大学 | Polyethylene dust explosion hazard prediction method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010008135A (en) * | 2008-06-25 | 2010-01-14 | Gastec:Kk | Apparatus for explosion testing of combustible gas/vapor |
| CN102608161A (en) * | 2012-03-07 | 2012-07-25 | 北京理工大学 | Method for testing critical energy of detonation formed by direct initiation |
| CN112473068A (en) * | 2020-12-04 | 2021-03-12 | 中核建中核燃料元件有限公司 | High-activity material digestion device |
| CN117233210A (en) * | 2023-11-14 | 2023-12-15 | 山东科技大学 | Polyethylene dust explosion hazard prediction method |
| CN117233210B (en) * | 2023-11-14 | 2024-01-30 | 山东科技大学 | Polyethylene dust explosion hazard prediction method |
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