• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.29-32
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• 2014

The practical route for disposal of sewage sludge becomes energy recovery by combustion after its ocean dumping is banned in 2012 in Korea. Due to the high moisture content, however, sewage sludge is required to be dried before transport and combustion. In this study, pyrolysis and combustion characteristics of dried sewage sludge was investigated in a small-scale fixed bed reactor in order to provide fundamental data for energy recovery of the fuel. As the first step of combustion, the primary products of pyrolysis were analyzed in a fixed bed reactor for the condensable volatiles (tar), non-condensable gases, and char. For the combustion characteristics, another fixed bed reactor was constructed to monitor the weight and temperature of the fuel particles during ignition and combustion under different air flow rates. The test results were used to derive the ignition and burning rates.

• Resources Recycling
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• v.24 no.6
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• pp.3-8
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• 2015

Gasification characteristics and gas produced from a sewage sludge char were analyzed by using a thermobalance reactor, which is used for a reaction kinetic analysis by measuring weight change of materials at a desired temperature. Gasification reaction rate increased with increasing temperature and steam partial pressure due to the promotion of gasification reaction. Three models of gas-solid reaction were applied to the reaction kinetics analysis and modified volumetric reaction model was an appropriated model for the steam gasification of the sewage sludge char. Apparent activation energy and pre-exponential factors were evaluated as 155.5 kJ/mol and $14,087s^{-1}atm^{-1}$, respectively. The order of reaction on steam partial pressure was 0.68. Gas analysis was performed at $900^{\circ}C$ and hydrogen concentration was highest in the gas concentrations, which increased with increasing the steam partial pressure. Hydrogen concentration increased the most and hydrogen concentration in the produced gas was 2-4 times higher than that of carbon monoxide due to the gasification and water gas shift reaction.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.4
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• pp.65-74
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• 2002

This Study was investigated operating condition of pyrolysis processing for sludge disposal in sewage treatment plant. Important parameters studied include running time of pyrolysis, run time of dry and pyrolysis processing, water content of sewage sludge, solids amount of sewage sludge(TS%), condition of pyrolysis temperature. Most degradation reaction of sewage sludge are first order, it assumed first order and elucidated the kinetics. This was the basis of characteristics analysis of sludge degradation mechanism. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas product components was observed. Main components of gas and carbon product are a little difference with pyrolysis temperature, but it consist of $CH_4$, $C_2H_4$, $C_3H_8$, $C_4H_{10}$, toluene, $C_6H_6$, $SO_2$, CO etc. The gas of $C_1-C_4$ yield increased along with degradation temperature of $670^{\circ}C$ and oil yield decreased of $C_6H_6$ and $C_6H_5OH$ with temperature of $600^{\circ}C$. Particularly, low value added char yield 134kg/t at $670^{\circ}C$, but increased to 194kg/t at pyrolysis temperature of $600^{\circ}C$. In the result of elementary analysis on it, it is mainly composed of carbon. From this fact, in pyrolysis of sludge, it comfirmed that carbonization reaction occur at high temperature well.

• Resources Recycling
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• v.23 no.6
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• pp.47-53
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• 2014

Effective treatment and energy conversion technologies are necessary due to the ban of the dumping of organic waste including the sewage sludge. In this study, the kinetics of pyrolysis and combustion were derived in a TGA and thermobalance reactor, which is essential for thermal conversion of sewage sludge to energy. Three steps are shown for the pyrolysis in TGA and the different pre-exponential factors and activation energies are derived depending on the temperature range. Three models of gassolid reaction were applied to the reaction kinetics analysis for the combustion of sewage sludge char and shrinking core model was an appropriated model. Apparent activation energy and pre-exponential factor were evaluated and the effect of oxygen partial pressure was examined.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.236-245
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• 2000

A laboratory scale fluidized bed reactor was developed to treat the combustion characteristics of some fuels (wood, paper sludge, refuse derived fuel). The aims were to introduce the means of experiment and interpretation of the results and finally determine the particle characteristics on the pyrolysis and combustion process of the fuel. A single particle combustion process in the fluidized bed was closely observed. Understanding experimental facility characteristics and determining parameters were also carried out. The fuel combustion processes were observed by carbon conversion rate, recovery and mean carbon conversion time. They were estimated with the CO, $CO_2$ gas concentration monitored at the exit of the combustor. Fuel drying and pyrolysis process were governed by temperature distribution in the fuel particle. There was a significant overlap of the drying and devolatilization. However, transition process from devolatilization to char combustion seemed to be determined by mechanical solidity of the fuel particle after devolatilization process.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.11
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• pp.1132-1138
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• 2008

The study was carried out to investigate adsorption characteristic on hydrogen sulfide (H$_2$S) and methylmercaptan (CH$_3$SH) odor gas using the char made by a thermal decomposition of sewage sludge. The fixed bed adsorption experiments of the optimum L/D ratio could be 1.0, and adsorption capacity and break point increased with the increase of temperature. A simultaneous adsorption characteristic of H$_2$S and CH$_3$SH increased in breakthrough time and adsorption capacity more than single adsorption experiment, and CH$_3$SH had higher effective diffusivities than H$_2$S in same condition. The adsorption capacity of CH$_3$SH increased with fast velocity. When it was compared the produced absorbent with commercial activated carbon, As to adsorbent amount, it was H$_2$S 77% and CH$_3$SH 80% of commercial activated carbon.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.2
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• pp.52-60
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• 2004

The basic approach to sewage sludge is organic waste minimization, promotion of energy recovery; volume and weight reduction by final treatment, and environmentally final disposal of natural circulation. Dry and pyrolysis of maize was experimentally investigated in full-scale rotary kiln in semi-continuous operation. The operational parameters varied are the operating temperature $160{\sim}175^{\circ}C$ of dry and $450{\sim}800^{\circ}C$ of pyrolysis, the solids residence time 9 min for pyrolysis. Important parameters studied include the running time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas production components was observed. The gas of $C_1{\sim}C_3$ yield increased and oil of $C_4{\sim}C_6$ yield decreased along with pyrolysis temperature of $670^{\circ}C$ by the run time of 9 min.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.3
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• pp.42-50
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• 2003

Pyrolysis of maize is experimentally investigated in bench-scale rotary kiln in semi-continuous operation. The operational parameters varied are the temperature($450{\sim}800^{\circ}C$), the solids residence time(7~20 min). Important parameters studied include the running time, water content of sewage sludge, solids amount of sewage sludge(TS%) by the varied temperature. Also, with the increasing of temperature, how the yield of oil and char product change was observed, and the distribution of gas production components was observed. The gas of $C_1{\sim}C_3$ yield increased and oil of $C4{\sim}C6$ yield decreased along with pyrolysis temperature of $670^{\circ}C$ by the run time of 9 min. The results showed the expected strong influence of pyrolysis temperature and a noticeable influence of running time.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.213-220
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• 2002

This reserch was focused upon experimental study for wastewater reuse and conducted to evaluate optimum operating conditions of rapid filtration process such as filter flow rate, filtration time and backwashing condition for reuse of secondary-treated effluent using the pilot plant installed in real wastewater treatment plant. Also, the experiment on treatment char-acteristics of coagulant-added activated sludge process was performed to compare with activated sludge succeeded to rapid filtration. As the filtration velocity was 100m/day, the filtration time of the rapid filter connected with activated sludge system was revealed to 40 hours. Backwashing of filter was conducted by water wash and air scour. The optimum backwashing time and backwash flow rate were 10min and 10LPM, respectively. The quantity of backwashing water of the rapid filter was about 2% of total treated water.