석탄 가스화기에서의 고알루미나 내화물의 손상 기구 규명

김유나; 이재구; 오명숙; Yuna Kim; Jae Goo Lee; Myongsook S. Oh

Journal of the Korean Industrial and Engineering Chemistry, Vol.20, No.6, 638-645, December, 2009

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석탄 가스화기에서의 고알루미나 내화물의 손상 기구 규명

Investigation of Degradation Mechanism of High Alumina Refractory in a Coal Gasifier

김유나, 이재구 ¹, 오명숙 ^†

홍익대학교 신소재화공시스템공학부
¹한국에너지기술연구원

Yuna Kim, Jae Goo Lee¹, and Myongsook S. Oh^†

School of Chemical Engineering and Materials Science, Hongik University, Seoul 120-791, Korea
¹Korea Institute of Energy Research, Daejeon 305-343, Korea

E-mail:

초록

가스화기에서 사용된 고알루미나계 내화물을 분석하여 용융 슬래그에 의한 손상 메커니즘을 조사하였다. 내화물 시료에서 슬래그에 의해 심하게 손상된 부분의 깊이는 부착된 슬래그를 포함하여 12∼40 mm이었으며 슬래그 접촉면과 평행 방향으로 형성된 균열을 가지고 있었다. 슬래그와 접촉한 내화물은 미세구조에 따라 손상도가 다르게 나타났다. Fused Al2O3 그레인의 경우 경계에서만 깨짐과 기공형성이 관찰되었고, tablet Al2O3의 경우 슬래그가 입자사이로 침투하여 입자 테두리에 Fe-Al 화합물이 관찰되었다. 결합제로 쓰인 calcium aluminate는 고온의 슬래그 접촉면에서는 슬래그에 용해되어 관찰되지 않았다. 큰 grain 주변에는 냉각 시 재결정된 것으로 보이는 막대형의 Al2O3 상이 형성되었고 큰 기공들이 관찰되었다. 따라서 고알루미나계 내화물은 고온의 슬래그 경계면에서 결합제가 석탄 슬래그에 용융되고, 냉각 시 막대형의 알루미나를 형성하며, 이 과정에서 구조적인 변화에 의한 크랙이 형성되면서 구조적 스폴링에 의한 물리적 손상의 영향을 받는 것으로 보인다.

High alumina refractory used in a coal gasifier was analyzed and the degradation mechanism by molten slag was investigated. The depth of refractory severely damaged by slag varied between 12∼40 mm, including the adhered slag layer. The sample also showed the cracks formed in parallel to the slag/refractory interface. The degree of degradation varied with the micro-structures in the refractory. Fused alumina grains showed the uneven boundary and pore formation just along the edges, while the tablet alumina showed the slag penetrated between sintered alumina around which the formation of Al-Fe phase was observed. Calcium aluminate cements were not observed at the high temperature zone near the slag/refractory interface, probably due to dissolution into molten slag. Around large grains of alumina, rod shape alumina, which appeared to be recrystallized during cooling, were observed, and large pores were also formed around those grains. Therefore, in high alumina refractories, hot molten slag dissolves the bonding phase and rod-shape alumina phase is recrystallized upon cooling. During this process, cracks are developed due to structural change, and the degradation occurs by physical causes such as structural spalling.

Keywords:gasification;high alumina refractory;coal slag;degradation

[References]

Kim SD, Coal Energy Conversion Technologies, Mineumsa (1986)
Coal IGCC Demonstration Plant Design and Construction Planing Report, MOCIE (2006)
Bennett JP, Kwang KS, Refractories Applications and News, 9, 20 (2004)
Kim H, Refractory Materials Engineering, KORICO (2000)
Kim HB, Thesis MS, Hongik University, Seoul, Korea (2002)
Banerjee S, Monolithic refractories, World Scientific Pub. Co. Pte. Ltd and ACS, Westerville, OH (1998)
Lee WE, Zhang S, Karakus M, J. Mater. Sci., 39(22), 6675 (2004)
Kim HB, Oh MS, Int. J. Ceramics, 34, 2107 (2008)
Kim HB, Oh MS, Energy Eng. J., 13, 281 (2004)
Moon I, Cho CB, Oh MS, Energy Eng. J., 11, 149 (2002)
Levin EM, Robins CR, McMurdie HF, Phase diagrams for Ceramist, ACS (1964)
Pelton AD, Pure & App. Chem., 69, 969 (1997)
www.factsage.com

[Related Articles]

[1] Kim SD, Coal Energy Conversion Technologies, Mineumsa (1986)

[2] Coal IGCC Demonstration Plant Design and Construction Planing Report, MOCIE (2006)

[3] Bennett JP, Kwang KS, Refractories Applications and News, 9, 20 (2004)

[4] Kim H, Refractory Materials Engineering, KORICO (2000)

[5] Kim HB, Thesis MS, Hongik University, Seoul, Korea (2002)

[6] Banerjee S, Monolithic refractories, World Scientific Pub. Co. Pte. Ltd and ACS, Westerville, OH (1998)

[7] Lee WE, Zhang S, Karakus M, J. Mater. Sci., 39(22), 6675 (2004)

[8] Kim HB, Oh MS, Int. J. Ceramics, 34, 2107 (2008)

[9] Kim HB, Oh MS, Energy Eng. J., 13, 281 (2004)

[10] Moon I, Cho CB, Oh MS, Energy Eng. J., 11, 149 (2002)

[11] Levin EM, Robins CR, McMurdie HF, Phase diagrams for Ceramist, ACS (1964)

[12] Pelton AD, Pure & App. Chem., 69, 969 (1997)

[13] www.factsage.com