• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.197-197
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• 2010

음식물쓰레기의 삼성분은 수분, 휘발분, 회분이며 이들이 차지하는 비율은 계절, 지역별로 다소 상이하지만 수분 약 80%, 회분3%, 휘발분 17%이다. 음식물쓰레기 전처리과정으로 이물질제거, 탈수공정이 있으며 탈수공정에서 다량의 탈리액이 발생한다. 본 연구에서는 탈리액을 데칸타를 이용하여 1차로 원심분리하여 고.액 분리한 액을 실험대상으로 하였다. 실험대상 탈리액의 물성은 BOD 78,800[mg/l], COD 41,000[mg/l], 부유물질 25,900[mg/l], 총질소 928[mg/l]이었다. 탈리액에는 기름성분(육류, 식용유등), 입자상물질등이 포함되어 있으며 이들은 난분해성 유기물질로, 이를 제거하는데 기존의 처리방법으로 많은 어려움이 있어 주요한 수질오염 발생원이 되고 있다. 예를들면 하수처리장 폭기조 수면에 유막을 형성하여 산소공급을 방해함으로 미생물번식을 방해하는 요인이 된다. 본 연구는 음식물쓰레기 탈리액의 수분, 고형분, 유분으로의 삼상분리에 관한 것이다. 유분은 에멀젼형태로 안정되게 수층에 분산되어 존재한다. 미세기포를 이용한 부상법의 경우 미세기포 표면과 유분의 화학적친화력이 낮아 기포표면에 유분이 잘 부착되지 않으며, 원심분리 방법만으로는 유분 분리효율이 낮고, 추출에 의한 분리시 추출액이 다량 소요되고 처리시간이 길며 추출액 비용이 많이 소요된다. 탈리액을 유분, 슬러지, 수분으로 분리하면 환경오염을 일으키는 주요성분을 신재생에너지 원료로 활용할 수 있다. 유분의 주성분이 동식물성 유지이므로 전처리시 산촉매를 이용 수분과 유리지방산을 제거하고 염기성촉매를 이용하여 전이에스테르화 반응을 거치면 바이오디젤인 FAME과 글리세롤으로 변환하므로 글리세롤을 분리하면 바이오디젤을 얻을 수 있다. 슬러지는 입자상 물질로 착화가 잘 되고 건조하면 발열량이 높으며 중금속등에 오염되지 않아 청정연료로 활용이 가능하다. 실험실에서의 탈리액 삼상분리방법은 다음과 같다. 탈리액 30ml당 추출액으로 노말헥산을 1ml를 가한 다음 플라스크에서 $80^{\circ}C$로 가열 후 방냉한다. 가열중 노말헥산의 손실을 방지하기 위하여 증발가스를 콘덴서에서 응축하여 플라스크로 재순환한다. 탈리액을 플라스크에서 꺼내어 원심분리기 rack에 300-400g씩 병에 각각 넣고 4,000rpm으로 30분간 운전한다. 탈리액은 상부로부터 유분층, 미세입자층, 수층, 슬러지층으로 분리된다. 각 층의 계면에서 2종의 성분이 약간 섞일 수 있다. 유분을 분리한 후 유분층 잔존물과 미세입자층, 수층 상층부의 혼합물을 취하여 50g씩 병에 넣고 3,500rpm으로 10분간 운전한 후 유분을 분리한다. 마지막으로 미세입자층만을 3,500rpm으로 10분간 원심분리한 후 유분을 따로 분리한다. 얻어진 유분은 rotary evaporator에서 $120^{\circ}C$로 가열하여 유분과 노말헥산을 분리하며 분리효율을 제고하기 위하여 감압하에서 운전한다. 분리된 유분의 고위발열량이 9,450[Kcal/kg]이었으며 원소분석 결과 탄소 74.7%, 수소 12.55%, 질소 0.08%, 유황분 0.0003%이었다. 분리된 유분의 양은 계절별로 시료별로 다르며 가을철에는 1.6-1.9%, 여름철은 1.0-1.3%이었다. 분리된 슬러지로부터 Hg, As, Cr, Cd, Pb 중금속 성분이 검출되지 않았으며 수분 2.8%, 휘발분 76.85%, 회분 7.52%, 고정탄소 12.83%이었고 원소분석결과 탄소 45.25%, 수소 7.46%, 질소 5.05%, 산소 34.39%, 유황분 0.33%이었으며 저위발열량은 4,480[Kcal/kg]이었다. 분리된 슬러지 양은 11-19% 이었다.

• Journal of Animal Environmental Science
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• v.17 no.2
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• pp.131-138
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• 2011

This study was carried out to investigate on the composting characteristics variation accoding to air supply capacity in Pig manure. The composting of pig manure is economical and efficiently process. The fermented compost was added in pig manure mixed with sawdust was composting reators. Air supply capacity levels of fermented compost on the pig manure mixed with sawdust were regulated at 50, 100, 150 and 200$\ell/m^3$/min. respectively. The obtained results can be followed as bellow; The temperature variations of experimental composting piles during composting for the different of T-1 reach $40^{\circ}C$ in 2 days, T-2, T-3 and T-4 reach $60^{\circ}C$ in 2 days and T-3, T-4 maintained until 8 days. The decreases in water contents per each square meter for the different of T-1 (50 l/$m^3$/min), T-2(100 l/$m^3$/min), T-3(150 l/$m^3$/min) and T-4(200 l/$m^3$/min.), The decreases ratio in water contents was T-1, T-2, T-3 and T-4 were 15.4%, 28.8%, 33.4% and 35.2%. The decreases ratio in weight was T-1, T-2, T-3 and T-4 were 7.6%, 15.6%, 16.8% and 16.9% respectively. The variations of oxygen concentration from composting period in case of oxygen discharge concentration T-1, T-2, T-3 and T-4 were 9 ppm. respectively. Fertilizer components after composting were examined. Nitrogen contents of the T-1, T-2, T-3 and T-4 were 0.45%, 0.44%, 0.42% and 0.44%, and P2O5 contents were T-1, T-2, T-3 and T-4 were 0.37%, 0.41%, 0.42% and 0.44% respectively. Therefore, the compost curing air supply of air volumes at least 150$\ell$/min/min. or more to supply the aerobic composting pig manure normally are judged to be possible.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.652-659
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• 1999

The trend of poisoning of reforming catalyst along with the position of anodic catalyst bed was studied. Keeping the conditions that steam to carbon ratio was 2.5, operating voltage was 0.75 V, current density was $140mA/cm^2$, the unit cell was operated during 24 hrs at a steady state. And then the cell was stopped, the catalysts packed in the position of inlet, middle and outlet were sampled individually and then the amount of carbon, Li and K poisoned were analysed. After 100 hrs operated, the catalysts at the same positions were analysed at the same manner. The result of this experiment was as followings. After 24 hrs operated, the poisoning amounts of Li and K in the catalyst were 0.27 wt% at inlet, 0.23 wt% at middle and the highest value 1.59 wt% at outlet. After 100 hrs, the amount of poisoning is the highest in the catalyst packed at the inlet of unit cell. The performance simulation of unit cell explained these trends of poisoning catalysts. The simulation told that the catalyst in the region of the inlet of unit cell treated the 90% of initial methane flow rate and the highest electrochemical reaction happened in this region. So the catalysts of this region were the most poisoned with carbon, Li and K and also the rate of poisoning is faster than that of the catalyst at other regions. The temperature at the region of outlet of unit cell was $30^{\circ}C$ higher than that of other regions, so more Li, and K vaporized than at other regions and little reforming reaction at this region made the catalysts poisoning rate low.

• Food Science and Preservation
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• v.11 no.2
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• pp.250-256
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• 2004

The objectives of this study were to develop a new commercial grain cooler suited to domestic weather and post-harvesting conditions for paddy, and to evaluate the performance. A prototype grain cooler capable of cooling paddy of 200 tons within 24 hours was developed. The grain cooler was designed to control the refrigeration capacity from 0 to 100% by controlling the capacity of compressor with unloading solenoid valve and by changing the flow rates of hot refrigerant gas flowing into reheater and evaporator from compressor. And a controller with one chip microprocessor was developed to control temperature and relative humidity of cooling air. The maximum cooling capacity of the grain cooler was 35,284㎉/hr at condensing/evaporating pressure of 16.5/3.6 kgf/$\textrm{cm}^2$. Maximum flow rate of cooling air was 120 ㎥/min at static pressure of 279 mmAq. The total maximum required power was 22.8㎾, and total required energy was saved from 26.7 to 33.3% of maximum power depending on operating conditions. The coefficient of performance of refrigeration devices and total coefficient of performance of the grain cooler were 4.71 and 1.8, respectively.