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강준석,송지영,박서경,정아영,이정준,서인석,채선하,김성수,김한승 대한상하수도학회 2017 상하수도학회지 Vol.31 No.6
In this study, it is estimated that ceramic membrane process which can operate stably in harsh conditions replacing existing organic membrane connected with coagulation, sedimentation etc. . Jar-test was conducted by using artificial raw water containing kaolin and humic acid. It was observed that coagulant (A-PAC, 10.6%) 4mg/l is the optimal dose. As a results of evaluation of membrane single filtration process (A), coagulation-membrane filtration process (B) and coagulation-sedimentation-membrane filtration process (C), TMP variation is stable regardless of in Flux 2 m3/m2・day. But in Flux 5 m3/m2・day, it show change of 1-89.3 kpa by process. TMP of process (B) and (C) is increased 11.8, 0.6 kpa each. But, the (A) showed the greatest change of TMP. When evaluate (A) and (C) in Flux 10 m3/m2・day, TMP of (A) stopped operation being exceeded 120 kpa in 20 minutes. On the other hand, TMP of (C) is increased only 3 kpa in 120 minutes. Through this, membrane filtration process can be operated stably by using the linkage between the pretreatment process and the ceramic membrane filtration process. Turbidity of treated water remained under 0.1 NTU regardless of flux condition and DOC and UV254 showed a removal rate of 65-85%, 95% more each at process connected with pretreatment. Physical cleaning was carried out using water and air of 500kpa to show the recovery of pollutants formed on membrane surface by filtration. In (A) process, TMP has increased rapidly and decreased the recovery by physical cleaning as the flux rises. This means that contamination on membrane surface is irreversible fouling difficult to recover by using physical cleaning. Process (B) and (C) are observed high recovery rate of 60% more in high flux and especially recovery rate of process (B) is the highest at 95.8%. This can be judged that the coagulation flocs in the raw water formed cake layer with irreversible fouling and are favorable to physical cleaning. As a result of estimation, observe that ceramic membrane filtration connected with pretreatment improves efficiency of filtration and recovery rate of physical cleaning. And ceramic membrane which is possible to operate in the higher flux than organic membrane can be reduce the area of water purification facilities and secure a stable quantity of water by connecting the ceramic membrane with pretreatment process.
위험물 저장탱크 화재 시 미분무 수막의 복사열 차단 효과 평가
강준석,이치영 한국화재소방학회 2024 한국화재소방학회논문지 Vol.38 No.2
본 연구에서는 실규모 위험물 저장탱크 화재 시 미분무 수막의 복사열 차단 효과에 대한 전산해석을 수행하였다. 전산해석을 위해 fire dynamics simulator (FDS)를 이용하였고, 실규모 위험물 저장탱크 화재에 대한 기존 실험 연구를바탕으로 FDS의 열유속 예측 정확도를 확인하였다. 이후 실규모 위험물 저장탱크에 미분무 수막 설비를 설치하여,화원 조건과 미분무 수막 특성에 따른 열유속과 미분무 수막의 복사열 차단율을 검토하였다. 전산해석 결과, 화원이탱크 및 방유제이고, 노즐의 분사각이 크고 액적 크기가 작은 경우가 미분무 수막에 의해 열유속이 낮아지고 복사열차단율이 증가하는 것으로 나타났다. 인접 탱크 부근(노즐이 설치된 위치에서 지면으로부터 2∼14 m 높이 구간)에서미분무 수막에 의한 복사열 차단율은, 화원이 탱크 및 방유제인 경우와 탱크인 경우 각각 62.5∼72.4%와 33.5∼67.4%, 분사각이 180°와 90°인 경우 각각 62.5∼72.4%와 54.4∼65.3%, 액적 크기가 400 μm와 200 μm인 경우 각각62.5∼72.4%와 71.2∼83.0%로 측정되었다. 본 연구를 통해 실규모 위험물 저장탱크 화재 시 미분무 수막이 인접 탱크로의 복사열을 효과적으로 차단할 수 있음을 확인하였다 In this study, the thermal radiation blocking effect of a water mist curtain in a full-scale hazardous material storage tankfire was numerically simulated. A fire dynamics simulator (FDS) was used for the numerical simulation, and the accuracyof the heat flux prediction of the FDS was verified using an earlier experimental study on a full-scale hazardous materialstorage tank fire. Subsequently, a water mist curtain system was installed in a full-scale hazardous material storage tank,and the effects of fire source conditions and water mist curtain characteristics on the heat flux and thermal radiationblocking rate of the water mist curtain were examined. The results of the numerical simulation showed that the water mistcurtain decreased the heat flux and increased the thermal radiation blocking rate when the fire source was a tank and dikeand when the nozzle had a large spray angle and a small droplet size. Near the adjacent protected tank (in the height of2∼14 m from the ground at the nozzle installation position), the thermal radiation blocking rate of the water mist curtainwas measured to be 62.5∼72.4% and 33.5∼67.4% for the tank and dike fire and the tank fire, respectively, 62.5∼72.4%and 54.4∼65.3% for the spray angles of 180° and 90°, respectively, and 62.5∼72.4% and 71.2∼83.0% for the dropletsizes of 400 and 200 μm, respectively. This study confirmed that the water mist curtain could effectively block the thermalradiation from the fire tank to the adjacent tanks during a full-scale hazardous material storage tank fire.
막여과 정수처리공정에서 망간에 의한 막오염 특성 및 화학세정효율 평가
강준석,박서경,송지영,정아영,이정준,김한승 대한상하수도학회 2017 상하수도학회지 Vol.31 No.6
In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of 2.13 kgf/cm2, but it was recovered to the initial level (0.17 kgf/cm2) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.