퇴적금속분체의 입경 변화에 따른 화염전파 거동과 발화특성을 자체 제작한 실험장치와 열중량분석 시험장치를 활용하여 조사하였다. 이를 위하여 평균입경이 다른 Mg, Ti를 포함한 Zr, Ta, Mg-Al(90:10 wt%)의 금속분진과 PMMA 시료를 사용하였다. 그 결과, 금속 퇴적층의 두께가 5 mm 이상의 경우에는 화염전파속도의 퇴적층 두께에 대한 의존성이 나타나지 않았다. 평균 입경이 작을수록 Ti는 화염전파속도가 증가하지만 Mg의 경우에는 화염전파속도가 감소하였다. 평균입경 51 μm에 있어서 Mg퇴적분체는 Mg-Al(90:10%wt)합금 퇴적분체에 비하여 화염전파속도가 약 50%가 감소하였다. 본 연구에서 조사한 금속분체 산화물층 두께는 화염전파속도와 반비례하는 경향을 보였으며 입경 변화에 따른 영향은 나타나지 않았다. 또한 Ti와 Mg의 열중량 분석시험 결과, Mg는 550 ℃, Ta는 578 ℃에서 발화에 의한 연소로 판단되는 중량 증가가 관찰되었다.

A study has been conducted experimentally to investigate behavior of ignition and flame spread over metal dust deposits with particle size using by a developed apparatus and thermogravimetric analysis(TGA). Zr, Ta and Mg-Al(90:10 wt%) alloy metal powders including Mg and Ti with different particle size were used. Also we used PMMA(Polymethylmethacrylate) powder to compare the combustion properties to those of metal powders. When dust layers were more than 5 mm in thickness, the dependency of deposit depth on flame spread rate over dust layer was not shown. With decreasing mean particle diameter, flame spread rate over Ti dust layer decreased, while the spread rate over Mg dust layer increased. For mean diameter of 51 μm, fire spread rate over pure Mg dust layer decreased to about 50 percent in Mg-Al(90:10 wt%) dust layer. The oxide thickness of metal dust used in this study tended to be inversely proportional with the spread rate, and it was quite small for influence with particle size. From the results of TGA for Ti and Mg, weight increasing curves(550 for Mg, 578 for Ta) were observed in the oxidation process, and they seems to be caused by ignition of upper dust layer.

Metal Powders Dust Deposit Flame Spread Particle Size Spread Rate

Bartknecht W, “Dust Explosion,” Springer-Verlag, Berlin Heidelberg (1989)
Eckhoff RK, “Dust Explosion in the Process Industries; 3rd ed.,” BH (2003)
Coffin KP, “Some Physical Aspects of the Combustion of Magnesium Ribbons,” 5th Symp, Int. on Combust., The Combust. Inst., 267-276 (1955)
Harrison PL, Yoffe AD, Proc. Roy Soc., A261, 357 (1961)
Harrison PL, The Combust. Inst., 913 (1959)
Hirano T, Sato Y, Sato J, Combust. Sci. Tech, 32, 137 (1983)
Hirano T, Sato J, J. Loss Prev, in Process Indus., 6, 151 (1993)
Clark AF, Hust JG, AIAA J., 12, 441 (1974)
Chernenko EV, Afanaseva LF, Lebedeva VA, Explosion and Shock Waves, 30, 617 (1994)
Chernenko EV, Pivtsov AL, Explosion and Shock Waves, 26, 684 (1990)
Molodetsky IE, Vicenzi EP, Dreizin EL, Law CK, Combust. Flame, 112(4), 522 (1998)
Dreizin EI, Proc. Energy Combust. Sci., 26, 57 (2000)
Siwek R, Pellmont G, “Methods of Determination and Factors Influencing Hazard Evaluation in Dust Handling Equipment,” Proc. of Euromech Colloquium 208, Explosion in Industry, Germany (1986)
Roberts TA, Burton RL, Krier H, Combust. Flame, 92, 125 (1993)
Bakhman NN, Combust, Explosion Shock Waves, 29, 18 (1993)
Ohlemiller TJ, Combust. Flame, 81, 341 (1990)
Leisch SO, Kauffman CW, Sichel M, The Combust. Inst., 1601 (1984)
Hertzberg M, Zlochower IA, Cashdollar KL, “Metal Dust Combustion; Explosion Limits,” Pressure and Temperature, 24th Symp. Intl. on Combustion, The Combustion Institute, 1827 (1992)
Jacobson M, Cooper AR, Nagy J, “Explosibility of Metal Powders,” RI 6516, US Bureau of Mines (1964)