著者

越 光男 畑中 修二

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.60, no.193, pp.163-172, 2018 (Released:2019-02-15)

参考文献数

22

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A simple model for the smoke formation in black powder combustion is developed. Smoke formation is modeled as nucleation from gas phase molecules. The precursor molecules for this nucleation process for black powder with 75 wt% of KNO3 are identified as potassium salts such, K2CO3 and K2SO4. This determination is based on the partial-equilibrium calculations in which chemical species in the condensed phase are excluded. Standard classical nucleation theory (CNT) is adopted to estimate the radius and formation rate of the critical nuclei of smoke particles. The main components of smoke from black powder are K2CO3 or K2SO4 particles, depending on the sulfur content. The predicted nucleation rates of the particles are very fast. The time variation of the averaged particle radius and volume fraction of smoke is also evaluated by solving the population valance equation (Smoluchowski equation). The volume fraction of smoke produced by black powder combustion is predicted to be of the order of 10-4. This study also investigates how ammonium perchlorate (NH4ClO4, AP) added to the black powder affects smoke formation, using CNT and the Smoluchowski equation. CNT predicts that the critical radius of K2CO3 and K2SO4 particles can be considerably increased by the addition of AP to black powder. This intervention could thus reduce smoke-particle formation. Although CNT predicts that no KCl particles will form because of the high vapor pressure of KCl, the Smoluchowski equation indicates that KCl particles will be produced with a large amount of added AP. Solutions of the Smoluchowski equation also indicate that the average particle diameter and volume fraction of smoke decrease if the amount of added AP is increased.

著者

畑中 修二 薄葉 州

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.60, no.193, pp.181-190, 2018 (Released:2019-02-15)

参考文献数

20

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Japanese fireworks began in the Edo period. And the technology has advanced with the support by the people over time. Currently, Japanese fireworks are highly respected worldwide. I think the reason is that Japanese are creating the clear bright color and sound technology using the characteristics of aluminum powder (Al powder) well. On the other hand, severe accidents such as “mass explosion” which affect almost the entire explosives virtually instantaneously during manufacture and storage of fireworks articles including Al powder had continued until recently. It was similar in overseas. For this reason, investigation and research have been conducted at various levels, such as international, national and industrial levels, and regulations had been also tightened. International regulation on transportation of dangerous goods including fireworks should follow the regulation called "UN Recommendations". By these investigation and researches, the regulations of fireworks were changed dramatically in 2005, and then continued to change. Additionally, ISO standards of fireworks have been developed from 2012 and published in 2017. The transport classification of fireworks should be decided by the flash composition test of UN Recommendation. This flash composition test is composed of two kinds tests, a time pressure test with 0.5g sample and DDT test with 25g one. It became clear by Japanese studies that the time pressure test overestimates due to the scale effect. It seems that the combustion behavior of Al powder at high temperature and high pressure tightly relates to mass explosion, but the actual behavior is unknown now time.

著者

山隈 瑞樹 荒井 充 畑中 修二 細谷 文夫 飯田 光明 小勝 一弘

出版者

安全工学会

雑誌

安全工学 (ISSN:05704480)

巻号頁・発行日

vol.44, no.3, pp.165-173, 2005-06-15 (Released:2016-12-30)

参考文献数

13

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煙火薬製造における静電気危険性を把握するために,主要な工程を対象に帯電量の測定等を行った.その結果,ふるい分け作業において原料粉体が強く帯電することが判明した.硫黄の帯電量は際だって大きく,過塩素酸カリウムおよびアルミニウムはほぼ同等の帯電量であった.作業者が帯電防止をしていない場合には,2 kg のアルミニウム粉体のふるい分け作業によって最大15 kV に帯電した.小分け作業においては,アルミニウムをポリエチレン製スコップで取り扱った際に大きく帯電した.帯電した煙火粉体を絶縁性容器に入れた場合には,接地導体を接近させると粉体表面との間で着火性のある静電スパークが観測された.通常の作業条件においては,3 ~10 kg 程度の雷薬をふるい分けて絶縁性容器に入れると,これに着火可能な放電が発生すると見込まれた.