• Resources Recycling
• /
• v.17 no.6
• /
• pp.50-56
• /
• 2008

A polypropylene fraction collected from the stream of post-consumer plastics was pyrolyzed. The aim of this study is to observe the dependence of yield of BTEX-aromatics normally used as solvent on the reaction temperature. To reach the goal, three experiments were carried out at different temperature between 650 and $700^{\circ}C$, using a fluidized bed reactor that shows an excellent heat transfer. In the experiments, product gases were used as a fluidizing medium to maximize the amount of BTEX-aromatics at fixed flow rate and feed rate during the pyrolysis. Oil, gas and char were obtained as product fractions. Product gases were analyzed with GCs(TCD, FID) and with a GC-MS system for qualitative analysis. For an accurate analysis of product oil, the product oil was distilled under vacuum, and separated the distillation residues from oil fractions that were actually analyzed with a GC-MS system. As the reaction temperature went higher, the content of BTEX-aromatics increased. The maximal yield of BTEX-aromatics was obtained at $695^{\circ}C$ with a value of about 30%. The main compounds of product gas were $CH_4$, $C_2H_4$, $C_2H_6$, $C_3H_6$, $C_4H_{10}$ and the product gas had an higher heating value about 45MJ/kg. It could be used as a heat source for a pyrolysis plant or for other fuel applications.

• Clean Technology
• /
• v.22 no.4
• /
• pp.286-291
• /
• 2016

In this study we made fuel pellet from miscanthus biomass and investigated changes of physiological characteristics and electricity consumption of pelletizing process in comparison with fuel pellet made of pine sawdust. We also examined combustion characteristics including ash content and clinker forming ratio with fuel pellet made of mixing with micanthus biomass and lime powder. Bulk density of ground-miscanthus and pine sawdust were $158g\;L^{-1}$ and $187g\;L^{-1}$, respectively. Bulk density of ground miscanthus was lower than that of pine sawdust, but increased to $653g\;L^{-1}$ after pelletizing, which was similar to $656g\;L^{-1}$ of pine sawdust pellet. Moisture content in raw miscanthus and ground miscanthus were 17.0% and 11.8%, respectively. Moisture content in ground miscanthus was similar to that of pine saw dust and decreased to 6.73% after pelletizing, which was 7.7% lower than that of pine sawdust pellet. Although $27kWh\;ton^{-1}$ were required for compaction press that was an additional process in miscanthus pelleitizing, total required electricity was $193kWh\;ton^{-1}$ which was similar to $195kWh\;ton^{-1}$ of pine sawdust pellet pelleitizing. Pellet durability and pelletizing ratio of miscanthus were 98.0% and 99.7%, respectively, which were similar to 98.1% and 99.4% of pine sawdust pellet. When lime mixing ratio increased, ash melting degree and clinker forming ratio of miscanthus pellet increased. While higher heating value and clinker forming ratio of miscanthus pellet decreased.

• Applied Chemistry for Engineering
• /
• v.22 no.4
• /
• pp.429-432
• /
• 2011

The feasibility of applications of the char obtained from a gasification process of municipal-waste refuse derived fuel (RDF) as an auxiliary fuel was evaluated by combustion experiments. The higher heating value of the RDF char was 3000~4000 kcal/kg and its chlorine content was below the standard requirement demonstrating its potential as an auxiliary fuel. In the combustion exhaust gas, the maximum $NO_x$ and $SO_2$ concentrations were 240 ppm and 223 ppm, respectively. If an aftertreatment is applied, it is possible to control their concentrations low enough to meet the air pollutant emission standard. The HCl concentration was relatively high indicating that a care should be taken for HCl emission from the combustion of RDF. Based on the temperature distribution within the reactor, the concentration change of $O_2$ and $CO_2$, and the amount and the loss on ignition of solid residue, it was inferred that the combustion reaction was the most reliable when the excess air ratio of 1.3 was used.

• Clinical and Experimental Pediatrics
• /
• v.49 no.10
• /
• pp.1079-1085
• /
• 2006

Purpose : The purpose of this study was to evaluate factors affecting hematologic recovery and infection in high-dose chemotherapy(HDCT) and autologous stem cell transplantation(ASCT) in patients with high-risk solid tumor. Methods : From January 2004 to December 2005, 72 HDCTs and ASCTs were applied to children with high-risk solid tumor at Samsung Medical Center. Medical records of these 72 HDCTs and ASCTs were retrospectively analyzed. Results : The single most powerful predictor of neutrophil and platelet recovery was the number of transplanted $CD34^+$ cells. The duration of high fever was significantly longer in young patients, in patients treated with total body irradiation and/or thiotepa, and in patients transplanted with lower $CD34^+$ cell dose(<$2{\times}10^6/kg$). However, the difference in the duration of high fever according to the number of $CD34^+$ cells was not clinically significant. Conclusion : Findings in this study suggest that HDCT and ASCT with low $CD34^+$ cell dose is clinically feasible despite delayed hematologic recovery, especially at a dose >$1{\times}10^6/kg$ per transplantation. Therefore, it is important not to defer the appropriate time for HDCT for an additional collection of hematopoietic stem cells if the number of collected $CD34^+$ cells is >$1{\times}10^6/kg$ per transplantation.

• Tuberculosis and Respiratory Diseases
• /
• v.47 no.1
• /
• pp.77-89
• /
• 1999

Background: High-dose chemotherapy is increasingly employed in many refractory malignant diseases. This therapy has been reported to increase response rate and survival benefits but it is also associated with higher treatment-related morbidity and mortality. We evaluated clinical characteristics and course of the pulmonary toxicity following high-dose chemotherapy with peripheral blood stem cell transplantation. Methods: Ninety-seven patients who had received high-dose chemotherapy with peripheral blood stem cell transplantation were evaluated. Five patients who developed lung lesions which were not related to infection nor primary malignant disease underwent transbronchial lung biopsy. The patients' clinical characteristics, treatments, and prognosis were reviewed retrospectively. Results: Five patients(5.1%) developed idiopathic pneumonia syndrome. The high dose chemotherapy regimens employed were cyclophosphamide, BCNU, and cisplatin in 3 cases, one case of BCNU, etoposide, Ara-C, and cyclophosphamide combination, and a regimen consisting of BCNU, etoposide, Ara-C, and melphalan. The total dose of BCNU used was 300-400 mg/$m^2$ and that of cyclophosphsmide was 6,000 mg/$m^2$. All of 5 patients received radiation therapy before this treatment. After an average duration of 14 weeks (4-26 weeks) of high-dose chemotherapy, patients developed cough, dyspnea and fever. The chest X-rays showed bilateral diffuse infiltration in 3 cases and the focal infiltration in the other 2 cases. All the patients received corticosteroid therapy as a treatment for the lung lesions. Two of them progressed to acute respiratory distress syndrome and died. Three patients recovered without residual lung lesion but one of them died of dilated cardiomyopathy. Conclusion: High-dose chemotherapy with peripheral blood stem cell transplantation especially which containing BCNU regimen may develop idiopathic pneumonia syndrome related to pulmonary toxicity and corticosteroid therapy may be bel1eficial in some cases.

• Microbiology and Biotechnology Letters
• /
• v.44 no.3
• /
• pp.400-407
• /
• 2016

A unicellular green alga, Chlorella vulgaris KNUA027, was isolated from the roots of Panax ginseng seedlings and its biotechnological potential was investigated. The results of GC/MS analysis showed that C. vulgaris KNUA027 was rich in nutritionally important polyunsaturated fatty acids (PUFAs) such as alpha-linolenic acid (C_18:3 ω3, 45.8%, 50.8 mg/g) and hexadecatrienoic acid (C_16:3 ω3, 11.8%, 13.1 mg/g). Therefore, this Korean indigenous microalga may have potential as a source of omega-3 PUFAs. It was also found that the saturated palmitic acid (C_16:0, 37.1%, 41.2 mg/g), which is suitable for biodiesel production, was one of the major fatty acids produced by strain KNUA027. The proximate analysis showed that the volatile matter content was 88.5%, and the ultimate analysis indicated that the higher heating value was 19.8 MJ/kg. Therefore, the results from this research with C. vulgaris KNUA027 may provide the basis for the production of microalgae-based biofuels and biomass feedstock.

• Clean Technology
• /
• v.23 no.1
• /
• pp.80-89
• /
• 2017

The bubbling fluidized bed (BFB) reactor with a diameter of 0.1 m and a height of 1.2 m was used for experimental study of co-firing and emission characteristics fueled by sewage sludge (SS) and wood pellet (WP). The facility consists of a fluidized bed reactor, feeding system, cyclone, condenser and gas analyzer, The mean particle diameter and minimum fluidization velocity are $460{\mu}m$ and $0.21ms^{-1}$ respectively. SS produced from Korea and WP from Canada were examined. The various mixing ratios of WP were 20, 50, and 80% based on HHV. The equivalence ratio of 1.65, reactor temperature of $800^{\circ}C$, air flow rate of $100Lmin^{-1}$, and fluidization number of 4 were fixed in the BFB experiment. In TGA, the range of combustion temperature of SS was wider than that of WP. It represents that the combustibility of WP is higher than that of SS. The BFB reactor temperature was maintained between 800 and $900^{\circ}C$. CO emission of SS was high because of lower combustibility. $NO_X$ and $SO_X$ formation of SS were higher than that of WP since high nitrogen and sulfur contents of SS. CO, $NO_X$, and $SO_X$ formation were suppressed as the mixing ratio of WP was increased. The slagging and fouling tendencies show high in all test conditions.

• Clean Technology
• /
• v.27 no.1
• /
• pp.69-78
• /
• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• Clean Technology
• /
• v.29 no.3
• /
• pp.200-216
• /
• 2023

Ginkgo leaves are considered waste biomass and can cause problems due to the strong insecticidal actions of ginkgolide A, B, C, and J and bilobalide. However, Ginkgo leaf biomass has high organic matter content that can be converted into fuels and chemicals if suitable technologies can be developed. In this study, the effect of pyrolysis temperature, minimum fluidized velocity, and Ginkgo leaf size on product yields and product properties were systematically analyzed. Fast pyrolysis was conducted in a bubbling fluidized bed reactor at 400 to 550℃ using silica sand as a bed material. The yield of pyrolysis liquids ranged from 33.66 to 40.01 wt%. The CO₂ and CO contents were relatively high compared to light hydrocarbon gases because of decarboxylation and decarbonylation during pyrolysis. The CO content increased with the pyrolysis temperature while the CO₂ content decreased. When the experiment was conducted at 450℃ with a 3.0×U_mf fluidized velocity and a 0.43 to 0.71 mm particle size, the yield was 40.01 wt% and there was a heating value of 30.17 MJ/kg, respectively. The production of various phenol compounds and benzene derivatives in the bio-oil, which contains the high value products, was identified using GC-MS. This study demonstrated that fast pyrolysis is very robust and can be used for converting Ginkgo leaves into fuels and thus has the potential of becoming a method for waste recycling.

• Clean Technology
• /
• v.19 no.1
• /
• pp.30-37
• /
• 2013

Low-rank coal with high water content (32.3 wt%) was dried by fry drying, and the fuel characteristics of the dried coal from which the oil was separated by using a high-speed centrifugal separator were analyzed. After fry drying for 6 min and 10 min, the water content decreased to 5.0 wt% and 4.2 wt% respectively. The higher calorific value (HCV) of the coal increased remarkably after fry drying, from 11,442.0 kJ/kg-wet. The oil content of the fry-dried coal was 15.0 wt% and it decreased with an increase in the reheating temperature: 9.7 wt% at $80^{\circ}C$ to 9.3 wt% at $100^{\circ}C$, and then to 8.5 wt% at $120^{\circ}C$. The recovered oil could then be reused. According to of thermogravimetric analysis (TGA), there was no difference in the weight loss patterns of the coal samples with different coal diameters at a reheating temperature of $120^{\circ}C$. This was because the amount of oil separated by the centrifugal separator was affected by the reheating temperature rather than the coal diameter. And derivative thermogravimetry (DTG) curves of raw coal before the fry-drying process, a peak is formed at $400^{\circ}C$ in which the volatile matter is gasified. In case of the fry-dried coal, the first peak is generated at $350^{\circ}C$, and the second peak is generated at $400^{\circ}C$. The first peak is caused by the oil that is replaced with the water contained in the coal during the fry-drying process. Further, the peaks of the coal samples in which the oil is separated at a reheating temperature of $80^{\circ}C$, $100^{\circ}C$, $120^{\circ}C$, respectively are smaller than that of the coal in which the oil is not separated, and this is caused by that the oil is separated by the centrifugal separator.