JP4340666B2 - How to control mist explosions of flammable liquids - Google Patents
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本発明は、ミスト爆発におけるミストの下限界濃度および／または限界支燃性ガス濃度により、可燃性液体のミスト爆発を制御する方法に関する。 The present invention relates to a method for controlling a mist explosion of a flammable liquid according to a lower mist concentration and / or a limit flammable 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 for indicating the ease of electrostatic charge 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 ignited. 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 tested 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.
本発明は、ミストの下限界濃度や限界支燃性ガス濃度により、可燃性液体のミスト爆発を制御することにある。 An object of the present invention is to control the mist explosion of a flammable liquid by the lower limit concentration of mist or the limit flammable gas concentration.
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 have completed the present invention.
すなわち本発明は、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ミストの下限界濃度以下および／または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方法に関する。 That is, the present invention relates to the handling of the flammable liquid at a temperature below the flash point of the flammable liquid, and the flammable liquid is less than the lower limit concentration of mist in the mist explosion related to the flammable liquid and / or. The present invention relates to a method for controlling a mist explosion of a flammable liquid by adjusting the concentration to be below a limit combustion-supporting gas concentration in a mist explosion.
可燃性液体の取り扱いにおいて、ミストの下限界濃度や、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、ミストの下限界濃度や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 lower limit concentration of mist and 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 cause electrostatic explosions. However, if they exist in a medium such as air in a mist state, they may be charged and lead to explosions. Also, flammable liquids with such conductivity can be controlled by controlling and controlling the mist's lower limit concentration and limit flammable gas concentration, which can control mist explosions that could not have been expected only at the flash point. become.
なお、ミスト爆発は、通常、引火点未満の温度で起きるため、ミストの下限界濃度や、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。 Since mist explosions usually occur at temperatures below the flash point, the handling of flammable liquids can be handled safely without taking the flash point into consideration by managing the lower limit concentration of mist and the limit of the flammable gas. It can be carried out.
ミスト爆発におけるミストの下限界濃度の測定、ミスト爆発における限界支燃性ガス濃度の測定は、下記方法、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 lower limit concentration of the mist in the mist explosion and the measurement of the limit combustion-supporting gas concentration in the mist explosion can be more accurately controlled by using the following method and apparatus.
ミスト爆発におけるミストの下限界濃度の測定は、所定容積を確保しうる燃焼筒内に、被検可燃性液体をミスト状態で噴霧した後、燃焼筒内に噴霧されたミスト状態の被検可燃性液体の重量を、燃焼筒内でミスト状態を呈しなくなって燃焼筒内壁に付着・流下する被検可燃性液体の重量が関与しないようにして測定した結果から、ミスト濃度を割り出すとともに、被検可燃性液体の前記ミスト濃度での点火によるミスト爆発の有無を確認することによって、行うことができる。 The measurement of the lower limit concentration of mist in a mist explosion is performed by spraying a test flammable liquid in a mist state into a combustion cylinder that can secure a predetermined volume, and then spraying the test flammability in the mist state in the combustion cylinder. Determine the mist concentration from the result of measuring the weight of the liquid so that the weight of the flammable liquid that adheres and flows down on the inner wall of the combustion cylinder because it no longer exhibits the mist state in the combustion cylinder, and the test flammable This can be done by confirming the presence or absence of a mist explosion due to ignition at the mist concentration of the ionic liquid.
上記のように、燃焼筒の容積とミスト状態の被検可燃性液体の重量 (ミスト重量）から、ミスト濃度を割り出すにあたって、ミスト重量に、ミスト状態を呈しなくなった可燃性液体の重量を算入外とすることにより、燃焼筒内に存在するミスト重量を正確に把握できる結果、ミストの下限界濃度を正確に測定できるようになる。 As described above, when calculating the mist concentration from the volume of the combustion cylinder and the weight of the flammable liquid to be detected (mist weight), the weight of the flammable liquid that no longer exhibits the mist state is not included in the mist weight. As a result, the mist weight existing in the combustion cylinder can be accurately grasped, so that the lower limit concentration of mist can be accurately measured.
上記ミストの下限界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ミストの下限界濃度測定装置としては、たとえば、所定容積を確保しうる燃焼筒を有し、当該燃焼筒内には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し、当該燃焼筒の下部には燃焼筒内でミスト状態を呈しなくなって燃焼筒内壁に付着・流下する被検可燃性液体の回収槽を有し、かつ当該燃焼筒内でミスト発生後に自然落下するミスト重量を測定しうる測量計を備えたもの、が用いられる。 As an apparatus for measuring the lower limit concentration of a mist in a mist explosion of a combustible liquid used in the method for measuring the lower limit concentration of the mist, for example, there is a combustion cylinder capable of securing a predetermined volume, A flammable liquid mist generator and an igniter for explosive mist explosion, and the lower part of the combustion cylinder is no longer in the mist state in the combustion cylinder and adheres to and flows down the inner wall of the combustion cylinder What has a survey tank which has a liquid recovery tank and can measure the mist weight which falls naturally after mist generation in the combustion cylinder concerned is used.
当該下限界濃度測定装置によれば、燃焼筒の下部に設けた回収槽に、ミスト状態を呈しなくなって燃焼筒内壁に付着・流下する被検可燃性液体が溜まるため、燃焼筒内でミスト状態を呈しない被検可燃性液体は測量計の重量に加わらず、一方、燃焼筒内におけるミスト状態を呈する被検可燃性液体が自然落下することにより測量されて、燃焼筒内のミスト重量が正確に測量される。 According to the lower limit concentration measuring apparatus, since the flammable liquid that adheres and flows down on the inner wall of the combustion cylinder does not appear in the recovery tank provided in the lower part of the combustion cylinder and accumulates on the inner wall of the combustion cylinder, The test flammable liquid that does not exhibit the mist weight is not added to the weight of the surveying instrument, while the test flammable liquid that exhibits the mist state in the combustion cylinder is measured by the natural fall and the mist weight in the combustion cylinder is accurate. Surveyed.
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。下限界濃度測定装置におけるミスト発生装置は、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。 The mist generating device preferably has a mechanism for spraying a gas-liquid mixture. The mist generating device in the lower limit concentration measuring device is not particularly limited as long as it can generate mist, but mist explosion tends to occur easily when the average particle size of mist is smaller than 50 μm. Therefore, it is preferable to apply a nozzle having a mechanism for spraying a gas-liquid mixture that can form an average particle size of 50 μm or less.
前記燃焼筒の開口部は網状物とするのが好ましい。当該開口部の網状物によって燃焼筒は開放系になり、燃焼筒内に噴霧したミストの一部は、燃焼筒外に拡散されるが、燃焼筒外に拡散したミストは、燃焼筒内に逆戻りすることはなく、ミスト重量の測定に係わる燃焼筒の容積を明確に確保でき、燃焼筒内の所定容積に係わるミストのみが重量測定される。また網状物は、燃焼筒内でミスト爆発させた際に生じる爆風の燃焼筒外への風路を確保でき燃焼筒の破壊を防止できる。また、当該網状物は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止でき、測定上の安全性が向上する。 The opening of the combustion cylinder is preferably a mesh. The combustion cylinder becomes an open system by the mesh of the opening, and a part of the mist sprayed in the combustion cylinder is diffused outside the combustion cylinder, but the mist diffused outside the combustion cylinder returns to the combustion cylinder. The volume of the combustion cylinder related to the measurement of the mist weight can be clearly ensured, and only the mist related to the predetermined volume in the combustion cylinder is measured. Further, the net-like material can secure a wind path to the outside of the combustion cylinder of the blast generated when the mist is exploded in the combustion cylinder, and can prevent the destruction of the combustion cylinder. In addition, the mesh can act as a flame arrester to prevent a flame generated by a mist explosion from reaching the outside of the combustion cylinder, thereby improving measurement safety.
さらに、燃焼筒の開口部を錘状にするのが好ましい。燃焼筒上部を錘状にして傾斜を持たせることにより、燃焼筒の上面部においてミスト状態を呈しなくなった被検可燃性液体が壁面に沿って被検可燃性液体の回収槽に流下し易くなり、燃焼筒内のミスト重量の測定をより正確に行うことができる。 Furthermore, it is preferable that the opening of the combustion cylinder has a weight shape. By making the upper part of the combustion cylinder into a weight and giving it an inclination, it becomes easier for the combustible liquid that no longer exhibits a mist state on the upper surface of the combustion cylinder to flow down to the recovery tank of the combustible liquid along the wall surface. The mist weight in the combustion cylinder can be measured more accurately.
また、ミスト爆発における限界支燃性ガス濃度を測定は、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、行うことができる。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。 In addition, the limit combustion-supporting gas concentration in a mist explosion is measured by setting a predetermined combustion-supporting gas concentration in a substantially sealed combustion cylinder and spraying a test combustible liquid in a mist state before ignition. This can be done by checking for the presence or absence of an 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も、ミストの下限界濃度測定装置と同様に、前記ミスト発生装置を、気液混合物を噴霧させる仕組みからなるものにするのが好ましい。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。 In the limit combustion-supporting gas concentration measuring device, it is preferable that the mist generating device has a mechanism for spraying the gas-liquid mixture, similarly to the mist lower limit concentration measuring device. 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.
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下限界濃度測定装置に関するものである。燃焼筒１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。透明樹脂は、燃焼筒１内の燃焼を目視で観察でき、ミスト爆発の程度の把握が容易である。 FIG. 1 relates to an apparatus for measuring the lower limit concentration of mist in a mist explosion. The material of the combustion cylinder 1 is not particularly limited as long as it is heat resistant, but is preferably made of plastic that is easy to handle such as transportation, and particularly transparent resins such as polyvinyl chloride, polymethyl methacrylate, and polycarbonate. The transparent resin allows the combustion in the combustion cylinder 1 to be observed visually, and the degree of mist explosion is easy to grasp.
燃焼筒１は、下限界濃度測定の基準となる所定容積を有するものである。本発明でいう所定容積を確保しうる燃焼筒１とは、燃焼筒１内の噴霧状態のミストが自然落下することにより、測量計２に現れるミスト重量の数値として、そのまま反映されるように所定容積を確保しうるものであればよい。また、燃焼筒１内へはミストが加圧噴霧されるため、燃焼筒１は開放系であり、間隙が必要である。図１は、燃焼筒１の上部開口部は錘状の網状物１１が設けられて開放系になっている。当該網状物１１からはミストが飛散しうるが、飛散したミストは燃焼筒１内に戻ることはなく、燃焼筒１では測定に係わるミストの所定容積が確保されている。網状物としては、フレームアレスタに有効な金属素材、たとえば金網とするのが好ましい。 The combustion cylinder 1 has a predetermined volume serving as a reference for measuring the lower limit concentration. The combustion cylinder 1 capable of securing a predetermined volume according to the present invention is a predetermined value so as to be reflected as it is as a numerical value of the mist weight appearing in the surveying instrument 2 when the sprayed mist in the combustion cylinder 1 naturally falls. What is necessary is just to be able to ensure a volume. Further, since the mist is pressurized and sprayed into the combustion cylinder 1, the combustion cylinder 1 is an open system and a gap is required. In FIG. 1, the upper opening of the combustion cylinder 1 is provided with a weight-like net 11 and is an open system. Mist can scatter from the mesh 11, but the scattered mist does not return into the combustion cylinder 1, and a predetermined volume of mist for measurement is secured in the combustion cylinder 1. The net is preferably a metal material effective for a frame arrester, for example, a wire net.
燃焼筒１は、通常、高さ３００〜３０００ｍｍ程度であり、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程度とするのが好ましい。なお、ミスト濃度を割り出す際に使用する所定容積としては、燃焼筒１から測量計２に至るミストの落下の過程における最小径を元に算出する。したがって、図１では、燃焼筒１の直径でなく、回収槽７の直径を基準にする。 The combustion cylinder 1 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 the diameter is preferably about 100 to 1000 mm. The predetermined volume used when determining the mist concentration is calculated based on the minimum diameter in the process of mist dropping from the combustion cylinder 1 to the surveying meter 2. Therefore, in FIG. 1, not the diameter of the combustion cylinder 1 but the diameter of the recovery tank 7 is used as a reference.
また、燃焼筒１の底面には、燃焼筒１内でミスト状態を呈しなくなって燃焼筒１内壁に付着・流下する被検可燃性液体の回収槽７を有する。回収槽７は、燃焼筒１の底部の壁面に沿って設けられている。被検可燃性液体は、燃焼筒１内にミスト状態で噴霧されるが、ミストの一部は、燃焼筒１の内壁に付着・流下して、回収槽７に回収される。回収槽７には、排出管８を設けることにより、連続的に回収槽７から排出することもできる。 In addition, the bottom surface of the combustion cylinder 1 includes a recovery tank 7 for a combustible liquid to be detected that does not exhibit a mist state in the combustion cylinder 1 and adheres to and flows down from the inner wall of the combustion cylinder 1. The recovery tank 7 is provided along the wall surface of the bottom of the combustion cylinder 1. The test combustible liquid is sprayed in a mist state in the combustion cylinder 1, but a part of the mist adheres and flows down on the inner wall of the combustion cylinder 1 and is recovered in the recovery tank 7. The collection tank 7 can be continuously discharged from the collection tank 7 by providing a discharge pipe 8.
燃焼筒１内のミスト発生装置３の設置位置は特に制限されないが、図１に示すように、ミストを上向きに噴霧する場合には燃焼筒１の下部中央に設けるのが、燃焼筒１内のミストの分散性がよく好ましいが、ミスト発生装置３は上部中央に設けてミストを下向きに噴霧することもできる。ミスト発生装置３としては、たとえば、霧のいけうち社製の２流体ノズルＢＩＭ Ｋ６００７５やＢＩＭ Ｋ６０１５等が用いられる。ミスト発生装置３には、被検可燃性液体を導入するための液体導入管４と気体導入管５が接続されている。液体導入管４の液圧と気体導入管５の気圧を適宜に調整することにより、噴霧するミスト濃度が調整される。気体導入管５には、酸素、塩素、酸化窒素等の支燃性気体が用いられ、ミスト発生装置３により、燃焼筒１内に被検可燃性液体のミストを噴霧するとともに、支燃性気体を導入する。なお、支燃性気体としては、通常、空気が用いられる。 Although the installation position of the mist generating device 3 in the combustion cylinder 1 is not particularly limited, as shown in FIG. 1, when the mist is sprayed upward, it is provided in the lower center of the combustion cylinder 1 in the combustion cylinder 1. Although the dispersibility of mist is good and preferable, the mist generating device 3 can be provided in the upper center to spray the mist downward. As the mist generating device 3, for example, a two-fluid nozzle BIM K60075 or BIM K6015 manufactured by Mist Ikeuchiuchi is used. A liquid introduction pipe 4 and a gas introduction pipe 5 for introducing the test combustible liquid are connected to the mist generating device 3. The mist concentration to be sprayed is adjusted by appropriately adjusting the liquid pressure of the liquid introduction pipe 4 and the pressure of the gas introduction pipe 5. The gas introduction pipe 5 uses a flammable gas such as oxygen, chlorine, or nitrogen oxide. The mist generator 3 sprays the mist of the combustible liquid into the combustion cylinder 1 and also supports the flammable gas. Is introduced. Note that air is usually used as the combustion-supporting gas.
ミスト爆発させるための着火装置６の位置は特に制限されないが、図１に示すように、燃焼筒１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６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 6 for causing the mist explosion is not particularly limited, as shown in FIG. 1, it is preferable that the position is about 1/4 to 3/4 from the bottom of the height of the combustion cylinder 1. As the ignition device 6, for example, a discharge electrode, nichrome wire fusing, platinum wire fusing, or the like is used.
また、ミストの下限界濃度測定装置には、燃焼筒１内でミスト発生後に自然落下するミスト重量を測定するための測量計２を備えている。測量計２上には、通常、受皿９が設けられている。受皿９に、ミスト発生後に自然落下するミストが液状で溜まり、その重量が測定される。測量計２としては、遠隔指示パネルを備えうる電子天秤等の各種のものを使用できる。 Further, the lower limit concentration measuring device for mist includes a survey meter 2 for measuring the mist weight that naturally falls after the mist is generated in the combustion cylinder 1. A tray 9 is usually provided on the surveying instrument 2. Mist that naturally falls after the occurrence of mist is collected in a liquid state in the tray 9 and its weight is measured. As the surveying instrument 2, various types such as an electronic balance that can be provided with a remote instruction panel can be used.
受皿２上には、ミスト飛散防止壁１０を設けることができる。ミスト飛散防止壁１０は、必ずしも必要ではないが、ミスト噴霧後に自然落下するミストは軽く、回収槽７と受皿９の間を容易にすり抜けられるため、ミスト飛散を防止して、より正確にミスト重量を測定するために用いるのが好ましい。ミスト飛散防止壁１０は金網等の網状物とすることもできる。 A mist scattering prevention wall 10 can be provided on the tray 2. Although the mist scattering prevention wall 10 is not necessarily required, the mist that naturally falls after mist spraying is light and can easily pass between the collection tank 7 and the tray 9, thus preventing mist scattering and more accurately reducing the mist weight. It is preferably used for measuring. The mist scattering prevention wall 10 may be a net such as a wire net.
燃焼筒１、回収槽７は、ミスト状態を呈しなくなった被検可燃性液体の重量に係わるため、通常、別の支持体に支持されて測量計２に重量がかからないように設ける。たとえば、燃焼筒１は上方より吊るす等の手段により、回収槽７は、横方向の支持体により、測量計２に重量がかからないようにすることができる。また、回収槽７、ミスト発生装置３は、燃焼筒１にボルト等により固定することにより、測量計２に重量がかからないようにすることもできる。 Since the combustion cylinder 1 and the recovery tank 7 are related to the weight of the combustible liquid to be detected that is no longer in the mist state, the combustion cylinder 1 and the recovery tank 7 are usually provided so as to be supported by another support so as not to apply weight to the surveying instrument 2. For example, the combustion cylinder 1 can be suspended from above, and the collection tank 7 can be prevented from being weighted by the lateral support. Further, the collection tank 7 and the mist generating device 3 can be fixed to the combustion cylinder 1 with a bolt or the like so that the surveying meter 2 is not weighted.
上記図１に示す下限界濃度測定装置を実際に操作するにあたっては、まず、液体導入管４の液圧と気体導入管５の気圧を所定条件に適宜に調整して、ミスト発生装置３から被検可燃性液体を所定時間噴霧し、ミスト状態で燃焼筒１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。噴霧停止後、直ちに、測量計２の示す重量を確認する。噴霧停止してから、通常、６０〜３００秒程度放置して、浮遊ミストを自由落下させる。放置後、再度測量計２の示す重量を確認する。再度確認したときの重量増加分が、浮遊ミストが自由落下した結果示すミスト重量であり、これを燃焼筒１の容積で除算してミスト濃度を計算する。なお、当該ミスト濃度の計算には、重量増加分に回収槽７内に溜まった可燃性液体は算入されないため、正確な浮遊ミスト濃度となる。 In actually operating the lower limit concentration measuring apparatus shown in FIG. 1, first, the liquid pressure in the liquid introduction pipe 4 and the atmospheric pressure in the gas introduction pipe 5 are appropriately adjusted to predetermined conditions, and the mist generating apparatus 3 The testable combustible liquid is sprayed for a predetermined time and sprayed into the combustion cylinder 1 in a mist state. The spraying time is usually about 10 to 60 seconds. Immediately after stopping spraying, the weight indicated by the surveying instrument 2 is confirmed. After stopping spraying, it is usually left for about 60 to 300 seconds to allow the floating mist to fall freely. After leaving, check the weight of the surveying instrument 2 again. The amount of increase in weight when reconfirmed is the mist weight shown as a result of the free fall of the floating mist, which is divided by the volume of the combustion cylinder 1 to calculate the mist concentration. In the calculation of the mist concentration, since the combustible liquid accumulated in the collection tank 7 is not included in the increase in weight, an accurate floating mist concentration is obtained.
こうして所定条件で測定された浮遊ミスト濃度と同様の条件で、別途、被検可燃性液体を噴霧した後、着火装置６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１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１の上部に金網を用いているので、ミスト爆発により炎が燃焼筒１外に殆ど出ない。 In this way, after separately spraying the test combustible liquid under the same conditions as the suspended mist concentration measured under the predetermined conditions, the ignition device 6 is ignited to confirm the presence or absence of the mist explosion. The confirmation of the presence or absence of the explosion is usually performed visually, but it can also be determined by inserting a thermocouple or the like into the combustion cylinder 1 and determining whether or not the temperature in the combustion cylinder 1 has risen. In the apparatus of FIG. 1, since a wire mesh is used in the upper part of the combustion cylinder 1, flame hardly appears outside the combustion cylinder 1 due to mist explosion.
この操作を、ミスト濃度を変更して繰り返して行うことにより、ミスト爆発するミスト濃度とミスト爆発しないミスト濃度を探って、最終的にミスト爆発のミストの下限界濃度を見出す。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望ましい。ミストの下限界濃度は、測定条件の中で燃焼が伝播しない最高のミスト濃度とすることができる。 By repeating this operation while changing the mist concentration, the mist concentration that explodes mist and the mist concentration that does not explode mist are searched, and finally the lower limit concentration of mist explosion is found. Since a mist explosion is likely to occur when the mist diameter is 50 μm or less, usually about 10 to 40 μm, it is desirable to check at least a mist diameter within the above range. The lower limit concentration of mist can be the highest mist concentration at which combustion does not propagate among the measurement conditions.
なお、ミスト爆発にあたっては、測量計２、受皿９、ミスト飛散防止壁１０、回収槽７は不要なので、これらを燃焼筒１から、取り外しておくのが、これらの燃焼変形、破損を防止でき好ましい。ただし、回収槽７が燃焼筒１に固定されている場合には、作業、操作等の便宜から特に取り外す必要はない。また、着火装置６を燃焼筒１の中央部よりも下部に設置した場合は、火炎は上方伝播しやすいため、ミスト爆発にあたって、測量計２等を燃焼筒１から取り外した場合、燃焼筒１の底部を開放口のまま使用できる。開放口は金網等の網状物で塞いで火炎の下方伝播を防ぐこともできる。 In addition, in the case of mist explosion, the surveying instrument 2, the receiving tray 9, the mist scattering prevention wall 10, and the recovery tank 7 are unnecessary, so it is preferable to remove them from the combustion cylinder 1 in order to prevent these combustion deformations and damages. . However, when the recovery tank 7 is fixed to the combustion cylinder 1, it is not particularly necessary to remove it for the convenience of work and operation. When the ignition device 6 is installed below the center of the combustion cylinder 1, the flame easily propagates upward. Therefore, when the surveying instrument 2 or the like is removed from the combustion cylinder 1 during a mist explosion, Can be used with the bottom open. The opening can be blocked with a net such as a wire mesh to prevent downward propagation of the flame.
図２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、前記下限界濃度測定装置と同様に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. 2 relates to a mist limit combustion-supporting gas concentration measuring apparatus in a mist explosion, and the material of the combustion cylinder 21 for causing mist explosion is heat-resistant as in the lower limit concentration measuring apparatus. Although not particularly limited, plastics that are easy to handle such as transportation are preferable, 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２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、図１の網状物１１と同様に火炎の伝播を遮断する。また、網状物２２ａ、２３としては、網状物１１と同様に金属素材の金網が好ましい。 In FIG. 2, 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 so that the inside of the combustion cylinder 21 is 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 destroyed by the explosion to prevent the combustion cylinder 21 from being damaged, and the reticulates 22a and 23 block the propagation of the flame in the same manner as the reticulate 11 in FIG. Further, as the nets 22 a and 23, like the net 11, a metal 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、底面部に図１のミスト回収槽７を設けるのが好ましい。 Further, it is preferable that the thin film 24 covers the bottom surface part with some allowance so that the dropped mist can collect. When the amount of mist dropped on the thin film 24 increases, the thin film 24 may be peeled off. Therefore, when providing the mesh 23, it is preferable to provide the mist collection tank 7 of FIG.
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２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. 2, 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２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。 The position of the ignition device 31 for causing the mist explosion is not particularly limited. However, as shown in FIG. 2, 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２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。 When actually operating the critical combustion-supporting gas concentration measuring apparatus shown in FIG. 2 above, while measuring the inside of the combustion cylinder 21 with the combustion-supporting gas concentration meter 27, for example, from the combustion-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２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 confirm the presence or absence 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. 2, 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下限界濃度、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下限界濃度以下および／または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。ミストの下限界濃度、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、図２の装置によれば、正確な値を把握できる。 In this way, the lower limit concentration of mist in the mist explosion of the flammable liquid, the limit flammable gas concentration can be accurately measured, and when handling the flammable liquid at a temperature below the flash point of the flammable liquid, By adjusting the flammable liquid mist below the lower limit concentration and / or below the limit flammable gas concentration, the mist explosion of the flammable liquid can be controlled and safe operation becomes possible. The measurement of the lower limit concentration of the mist and the limit flammable gas concentration can be obtained accurately according to the method and apparatus of the present invention, particularly the apparatus shown in FIGS.
可燃性液体の存在する系内におけるミストの濃度をミスト爆発が起きないように調整する手段としては、ミスト濃度が高くなってきた際に、たとえば、ガスによりミスト雰囲気を希釈化する方法、ミスト発生の原因となる液体流量を低下させる方法等によりミスト濃度を下げる方法等があげられる。 As a means of adjusting the concentration of mist in the system where flammable liquid exists so that mist explosion does not occur, when mist concentration becomes high, for example, a method of diluting mist atmosphere with gas, mist generation For example, there is a method of reducing the mist concentration by a method of reducing the liquid flow rate causing the above.
また、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。 In addition, means for adjusting the concentration of the flammable gas in the system where the flammable liquid exists so that the mist explosion does not occur is, for example, the concentration of the flammable gas by a non-combustible gas such as nitrogen, carbon dioxide, and steam. For example, a method of lowering the concentration of the flammable gas in the system in which the flammable liquid is present may be mentioned.
こうしたミスト爆発の制御にあたっては、限界支燃性ガス濃度の調整の方が容易に行うことができる。 In controlling such a mist explosion, it is easier to adjust the limit combustion-supporting gas concentration.
実際の操業にあたっては、ミストの下限界濃度、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。ミスト濃度に関してはミストの下限界濃度よりも ６０％程度低い条件下、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 lower limit value of the mist and the limit value of the limit flammable gas concentration. It is preferable to operate under the condition that the mist concentration is about 60% lower than the lower limit concentration of mist and the support gas concentration is about 60% lower than the limit support 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
ミストの下限界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℃）の下限界濃度を測定した例を示す。燃焼筒１の高さ２ｍ、内径０. ６ｍ、回収槽７の内径０．５５ｍ、測量計２上部から燃焼筒１上部までの高さ２．１ｍ、平面形状の網状物１１、ミスト濃度算出所定容積０．５ｍ3のものを用い、表１に示すように液体導入管４の液圧と気体導入管５の気圧（空気）を変化させてミスト量を調整した。その他、点火実験時の気温２１℃、湿度５４％、噴霧空気温度２２℃、噴霧液温度２０〜２１℃、噴霧時間４０秒の条件であり、ミスト濃度測定時の気温１６．５〜２２℃、湿度５７〜７４％、噴霧空気温度１７〜２５℃、噴霧液温度１６〜１８℃、噴霧時間４０秒、噴霧停止後の計測時間１８０秒の条件である。表１にミスト量、ミスト濃度、ミスト爆発の有無の判定を示す。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１内全体に燃焼が伝播、×：点火しても燃焼非伝播、を示す。
Example 1
As a specific example of the measurement of the lower limit concentration of mist, an example in which the lower limit concentration of combustible liquid (2-ethylhexanol, flash point 73 ° C.) is measured using an apparatus as shown in FIG. Combustion cylinder 1 height 2 m, inner diameter 0.6 m, recovery tank 7 inner diameter 0.55 m, height from surveying instrument 2 upper part to combustion cylinder 1 upper part, planar net 11, mist concentration calculation predetermined used as a volume 0.5 m 3, to adjust the mist quantity of liquid introduction pipe 4 fluid pressure and pressure of the gas inlet pipe 5 (air) varied as shown in Table 1. In addition, the temperature is 21 ° C. at the time of the ignition experiment, the humidity is 54%, the spray air temperature is 22 ° C., the spray liquid temperature is 20 to 21 ° C., and the spray time is 40 seconds. The humidity is 57 to 74%, the spraying air temperature is 17 to 25 ° C., the spray liquid temperature is 16 to 18 ° C., the spraying time is 40 seconds, and the measurement time after spraying is stopped is 180 seconds. Table 1 shows the mist amount, mist concentration, and the presence / absence of mist explosion. The item for determining the presence or absence of a mist explosion indicates ◯: a flame is visually observed by ignition and combustion propagates throughout the combustion cylinder 1, and x: combustion does not propagate even when ignited.
点火は同一噴霧圧力条件で最大３回実施し、１回でも燃焼が伝播すれば爆発すると判定し、３回とも燃焼が伝播しない場合を爆発しないと判定した。ミスト濃度の測定は同一噴霧圧力条件で５回実施し、最小値と最大値を削除して中間の３つの測定値を平均して算出した。 Ignition was performed a maximum of 3 times under the same spray pressure conditions, and it was determined that explosion would occur if combustion was propagated even once. The mist concentration was measured five times under the same spraying pressure condition, and the minimum and maximum values were deleted and the middle three measured values were averaged.
表１から、２−エチルヘキサノールに関して、ミスト爆発のミストの下限界濃度は約１５ｇ／ｍ3であることが認められる。 From Table 1, it can be seen that for 2-ethylhexanol, the lower limit concentration of mist for mist explosion is about 15 g / m 3 .
実施例２
ミストの限界支燃性ガス濃度測定の具体例として、図２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２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２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２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 2
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 2, air and non-combustible gas are used as shown in Table 2 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 2, 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 2 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 observable 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２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 2, it can be seen that for 2-ethylhexanol, the limiting oxygen for mist explosion is about 11%.
１：燃焼筒
２：測量計
３：ミスト発生装置
６：着火装置
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
1: Combustion cylinder 2: Survey meter 3: Mist generator 6: Ignition apparatus 21: Combustion cylinder 25: Combustion gas introduction pipe 27: Combustion gas concentration meter 28: Mist generation apparatus 31: Ignition apparatus
Claims (11)
ミスト爆発におけるミストの下限界濃度として、
所定容積を確保しうる燃焼筒内に、被検可燃性液体をミスト状態で噴霧した後、燃焼筒内に噴霧されたミスト状態の被検可燃性液体の重量を、燃焼筒内でミスト状態を呈しなくなって燃焼筒内壁に付着・流下する被検可燃性液体の重量が関与しないようにして測定した結果から、ミスト濃度を割り出すとともに、被検可燃性液体の前記ミスト濃度での点火によるミスト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ミストの下限界濃度を測定する方法により求めたものを用いる可燃性液体のミスト爆発を制御する方法。 When handling a flammable liquid at a temperature below the flash point of the flammable liquid, the flammable liquid may be used at a concentration below the lower limit of mist in a mist explosion and / or It is a method to control the mist explosion of flammable liquid by adjusting it to below the flammable gas concentration ,
As the lower limit concentration of mist in mist explosion,
After the test combustible liquid is sprayed in the mist state in the combustion cylinder capable of securing a predetermined volume, the weight of the mist test combustible liquid sprayed in the combustion cylinder is changed to the mist state in the combustion cylinder. The mist concentration is determined from the result of measurement so that the weight of the test flammable liquid that does not appear and adheres to and flows down the inner wall of the combustion cylinder is not involved, and the mist explosion caused by ignition of the test flammable liquid at the mist concentration A method for controlling the mist explosion of a flammable liquid using what was determined by the method of measuring the lower limit concentration of mist in a mist explosion by checking the presence or absence of mist.
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| CN104931531A (en) * | 2015-06-04 | 2015-09-23 | 西安近代化学研究所 | Method for testing pressure during heating process of explosive and propellant columns |
| CN106198086A (en) * | 2016-08-24 | 2016-12-07 | 安徽理工大学 | A kind of experimental system of coal mine gas from explosion baffling device |
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| CN105136852A (en) * | 2015-09-11 | 2015-12-09 | 中国石油化工股份有限公司 | Combustibility evaluation method of metal powder and solvent mixture thereof |
| CN106483164A (en) * | 2016-10-27 | 2017-03-08 | 北京润道油液监测技术有限公司 | For testing test system and the method for oil sample close flash point |
| CN117233210B (en) * | 2023-11-14 | 2024-01-30 | 山东科技大学 | Polyethylene dust explosion hazard prediction method |
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| CN104931531A (en) * | 2015-06-04 | 2015-09-23 | 西安近代化学研究所 | Method for testing pressure during heating process of explosive and propellant columns |
| CN106198086A (en) * | 2016-08-24 | 2016-12-07 | 安徽理工大学 | A kind of experimental system of coal mine gas from explosion baffling device |
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