Journal of the Korean Institute of Gas (한국가스학회지)

The Korean Institute of GAS (한국가스학회)
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Hazards of Fire and Explosion of Wastewater Sludge in an Evaporative Concentration Process

폐수 증발농축 공정 슬러지의 화재·폭발 위험성

  • Yi-Rac Choi (Occupational Safety & Health Research Institute, KOSHA) ;
  • Ki-Hyuk Jung (Occupational Safety & Health Research Institute, KOSHA) ;
  • Joo-Yeob Lee (Gwangju Metropolitan Office, KOSHA)
  • 최이락 (한국산업안전보건공단 산업안전보건연구원) ;
  • 정기혁 (한국산업안전보건공단 산업안전보건연구원) ;
  • 이주엽 (한국산업안전보건공단 광주광역본부)
  • Received : 2024.10.18
  • Accepted : 2024.12.18
  • Published : 2024.12.31
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Abstract

In this study, the cause of fire and explosion accidents that occurred at a wastewater treatment facility using an evaporative concentration process was analyzed, and the fire and explosion hazards of three wastewater sludges discharged through the evaporative concentration process were evaluated. Both fire and explosion accidents were presumed to have started when the sludge decomposed due to the rise in temperature in the dryer. The results of differential scanning calorimetry(DSC) analysis showed that heat generation started at (143-155) ℃, and the thermal hazard evaluation under adiabatic conditions using accelerating rate calorimetry(ARC) showed that sample B-1 started self-heating at 125 ℃, and after approximately 22 hours, the temperature increased to 261 ℃ and the pressure to 39 bar, causing the container to rupture. The friction sensitivity was evaluated as level 6 for A-2 and level 7 for B-2, indicating that there was a possibility of decomposition or ignition by mechanical friction energy.

본 연구에서는 증발농축 공정을 사용하는 폐수 수탁업 사업장에서 발생한 화재·폭발사고의 원인을 분석하고, 증발농축 공정을 통해 배출된 3개의 폐수 슬러지에 대해 화재·폭발 위험성을 평가하였다. 두 차례의 화재·폭발사고는 모두 건조기의 온도상승으로 슬러지가 분해되면서 시작된 발화로 추정되었다. 시차주사열량계(DSC) 분석 결과, (143~155) ℃에서 발열이 시작되었으며, 가속속도열량계(ARC)를 이용한 단열조건에서 열적 위험성을 평가한 결과, B-1 시료는 125 ℃에서 자기발열이 시작되었고 약 22시간 후 온도 261 ℃, 압력 39 bar까지 상승하면서 용기가 파열되었다. 마찰감도는 A-2는 6급, B-2는 7급으로 평가되어 기계적 마찰에너지에 의해 분해되거나 착화될 가능성이 있는 것으로 평가되었다.

Keywords

Acknowledgement

본 연구는 2023년 산업안전보건연구원의 재원으로 수행되었습니다.

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