Prakash Parthasarathy , Hang Seok Choi , Hoon Chae Park , Jae Gyu Hwang , Ho Seong Yoo , Byeong-kyu Lee

DOI:10.9786/kswm.2016.33.5.419

Abstract

High-rank coals are limited, while low-rank coals are abundant. However, the low-rank coals needs upgradation so as to improve their quality. If not, the utilization of low-rank coals will lead to many operational difficulties. As this study was made in South Korea, this article discusses the energy and coal scenario of South Korea. The critique discusses the concerns of utilizing low-grade coal and the need for upgrading low-grade coal. The article also briefly discusses the currently practiced low-rank coal upgradation techniques. Also, the review paper suggests some best upgradation techniques.

Key Words

South Korea, Coal scenario, Low-rank coal, Upgradation

정현태 Hyun-tae Joung , 백승기 Seong-ki Back , 조현호 Hyeun-ho Jo , 김성헌 Seong-heon Kim , 송한철 Han-cheul Song , 윤희철 Hee-chul Yoon , 홍정희 Jeong-hee Hong , 서용칠 Yong-chil Seo

DOI:10.9786/kswm.2016.33.5.446

Abstract

This study provides experimental results of pH restoration of acidified desulfurization seawater by the addition of the alkalinity enhanced seawater and additives (limestone and fly ash). The conservative seawater desulfurization processes use chemical solutions such as caustic soda (NaOH) or calcium hydroxide(Ca(OH)₂). The method proposed in this study was aimed at reducing usage of chemicals. A control test was conducted to simulate the existing process without addition of the alkalinity-enhanced seawater and additives (limestone and fly ash). The pH of desulfurized seawater was increased by pH 5.84 through the conservative restoration process (i.e., adding raw seawater and NaOH solution followed by aeration). The 20%, 50%, and 80% of added raw seawater was replaced by the alkalinity-enhanced seawater. From the experimental result, 0.28, 0.89, and 1.05 m³/hr of 48% NaOH solution could be saved when applying the proposed method of the alkalinity enhanced seawater addition. When desulfurized seawater with pH 3.5 was mixed with raw seawater at a ratio of 1:1, the pH of seawater was increased up to pH 6. Therefore, the seawater restoration goal was set as pH 3.5. Experiments were conducted to increase pH of desulfurized seawater to pH 3.5 using additives (fly ash and limestone). Based on these results, the addition of fly ash and limestone to seawater was proved effective for pH restoration of desulfurized seawater.

Key Words

Seawater, Desulfurization, Restoration, pH, Alkalinity

엄태인 Tae-in Ohm , 채종성 Jong-seong Chae , 문승현 Seung-hyun Moon

DOI:10.9786/kswm.2016.33.5.454

Abstract

Since 1987, the use of CFCs and HCFCs in various fields such as refrigerant of a refrigerator and a vehicle, a propellant for a spray, and a urethane foaming agent has been prohibited by Montreal protocol related to ozone depletion materials. Instead of the CFCs having a high ozone depletion potential (ODP), HFC-based refrigerants without a chlorine content were developed but determined as global warming materials. Therefore, to reduce greenhouse gas such as HFCs, including CFCs and HCFCs, having a global warming potential (GWP) of 150 or more, which is abandoned from the existing apparatus, it is required to develop a new eco-friendly, economic, and stable treatment technology. When the auxiliary fuel LPG was used at a flow of 1.0 kg/h with an air ratio of 1.1, the average temperature at the vertical section in the combustion chamber was 1,300 K, which is sufficient to destroy waste HFCs. In the waste refrigerant destruction test, the destruction ratio of waste HFCs was 100% when waste HFCs were injected at a flow of 2.8 kg/h.

Key Words

Numerical, HFCs, Incinerator, GWP, Non-CO₂

박정민 Jeong Min Park , 길상인 Sangin Keel , 윤진한 Jinhan Yun , 윤지혜 Ji Hye Yun , 오다솜 Dasom Oh , 이상섭 Sang-sup Lee

DOI:10.9786/kswm.2016.33.5.461

Abstract

There is an increasing demand for sustainable resources due to a steady increase in energy demand. As the1996 Protocol to the London Convention takes effect, conversion of sewage sludge to energy is increasing. To use waste as fuel, it is important to understand its combustion characteristics. Using thermogravimetric analysis, the combustion of coal, dried sewage sludge, and SRF was characterized in this study. Dried sludge and SRF showed similar combustion behavior at all temperature increase rates of 5, 10, 25, 40, and 100℃/min. Coal burned at a higher temperature as the temperature rate increased. This may be ascribed to the much higher volatile matter contents of dried sludge and SRF comparative to coal.

Key Words

SRF, Dried sludge, Combustion, TGA

김용주 Yongju Kim , 박민정 Minjung Park , 신미수 Misoo Shin , 이용국 Yongguk Lee , 장동순 Dongsoon Jang

DOI:10.9786/kswm.2016.33.5.467

Abstract

A parametric study has been made numerically on the thermal incineration of CF₄, one of the perfluorocarbons (PFCs) emerging recently as issues of public concern in a practical CDM incinerator developed for the thermal destruction of HFC-23. In doing this, a turbulent combustion model of the fast combustion approximation is reasonably assumed using the typical auxiliary fuel, CH₄, for the supply of the heat, and the necessary species of hydrogen and oxygen atom. In addition, the performance of the stoichiometric gas mixture of hydrogen and oxygen (H₂+ 1/2 O₂) was examined as a special auxiliary fuel not only in order to enhance the thermal destruction efficiency but also the reduction of the CO₂ emission by the elimination or the reduction of the auxiliary fuel CH₄ in this incineration process. The calculation results showed that the thermal destruction efficiency of CF₄ using methane as an auxiliary fuel increases with the amount of methane. However, the thermal destruction efficiency did not reach a satisfactory level (i.e., < 95%), even with the application of a CH₄ amount more than four times of the stoichiometric value. This is explained by the improper turbulent mixing effect between CH₄, CF₄ and air especially in a large scale practical incinerator employed for the destruction of HFC-23. For the case of H2+ 1/2 O₂ as the auxiliary fuel, however, the thermal destruction efficiency, surprisingly, reached almost 100%, which shows the high potential of the thermal destruction of CF₄ by the use of HHO gas. Further, a detailed evaluation for the effect of the turbulent mixing on the thermal destruction of CF₄ will be quite necessary, considering operating conditions together with the type of auxiliary fuels.

Key Words

PFCs, CF₄, Thermal decomposition, Numerical simulation

박일정 Il Jeong Park , 김건홍 Geon Hong Kim , 정항철 Hang Chul Jung

DOI:10.9786/kswm.2016.33.5.474

Abstract

In this paper, tin-waste resources were pulverized and separated by cut-mill and multi cyclone separator, respectively. After the cut-mill process, more than 98% of the Pb-Sn and Sn-Ag-Cu scraps were recovered, and the by-products consisting of metal and oxide could be reused as solder. The separation of pulverized powders was performed using the minimum fluidization velocity depending on the density of the materials. When the flow rate was 21 L/min (70% blower output), it had the highest separation efficiency.

Key Words

Tin (Sn), Recycling, Pre-treatment, Separation

고영재 Youngjae Ko , 장용철 Yong-chul Jang

DOI:10.9786/kswm.2016.33.5.483

Abstract

In this study, the recycling processes of construction and demolition waste (C&D waste) were analyzed, and its national recycling rate was determined using material flow analysis (MFA). Available statistical data provided by Ministry of Environment and Korea Environment Corporation were used for the MFA study. The collected data were carefully examined and validated by field investigations. System boundary for MFA covered from waste generation from construction sites to final disposal in 2013. The field investigation showed that recycled aggregate is produced through mechanical shredding, separation, and screening processes of C&D waste. The production efficiency (or process yield) was estimated to be approximately 81.2% on average. The foreign materials in the waste accounted for 18.8% by weight. The separated impurities were sent to recycling facilities, incineration facilities, or landfill sites, depending on the physico-chemical characteristics. Efficiency of recycling facilities and the statistical data were integrated to estimate the national actual recycling rate, which turned out to be 87.7% in 2013. Approximately 49.1% of the construction-related waste was recycled as recycled aggregate for concrete production and road base layer for asphalt pavement. Based on the result of MFA, there is 9.8% difference between the actual recycling rate in this study and reported recycling rate by national statistics. In the future, more various C&D waste treatment and disposal facilities, along with aggregate recycling facility, should be investigated to verify the actual recycling rate determined by this study. Statistical accuracy should be further refined through additional field investigations. Our findings can be applicable to development of recycling policies and best management practices for C&D waste streams.

Key Words

Construction and demolition waste, Actual recycling rate, Material flow analysis (MFA), Recycling

백승기 Seung-ki Back , 정법묵 Bup-mook Jeong , 성진호 Jin-ho Sung , 장하나 Ha-na Jang , 서용칠 Yong-chil Seo , 정다위 David Chung , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2016.33.5.492

Abstract

This study focused on the evaluation of stability of mercury compounds in byproducts from industrial facilities. Stability testing was conducted using a 5-step sequential extraction procedure using six kinds of byproducts. The mercury compounds extracted were categorized as ion-exchangeable (F1), acid soluble (F2), organic matter-bound (F3), strong complex (F4), and residual (F5) mercury compounds. The amount of mercury in each step was calculated and compared with total mercury amount; a 51% to 92% recovery rate was estimated. Hg-extracted F1, F2, and F3 were easily released into environment. It is necessary to apply an appropriate method to handle byproducts that contain these portions of mercury. On the other hand, mercury in F4 and F5 fraction is relatively more stable. F4 fraction means strong complex and elemental mercury. Byproduct from metal production facility has a higher elemental mercury fraction. It was found that 89% and 65% of mercury were contained in F4 fractions from fly ash and sludge, respectively. The goal of this study is to investigate stability of Hg compounds in different byproducts to suggest appropriate treatment methods for each byproduct on its Hg compound characteristics.

Key Words

Mercury, Stability, Byproduct, Sequential extraction procedure

이윤영 Yoon Young Lee , 김병환 Byung Hwan Kim , 유승관 Seung-kwan Yoo , 박진원 Jinwon Park

DOI:10.9786/kswm.2016.33.5.499

Abstract

Municipal solid waste incinerator (MSWI) fly ash was used for accelerated carbonation via bubbling of gaseous carbon dioxide (CO₂) after treatment with sodium hydroxide (NaOH). The influence of alkaline concentration and volumetric flowrate of CO₂ was investigated. Experimental results showed that carbonation reduced the leaching of Cu, Pb, Zn, and Cr. The pH of leachate decreased from around 12 to 10.5. The content of soluble chlorides was also decreased after carbonation. Additionally, the application of accelerated carbonation enhanced the sequestration of CO₂ from MSW incineration plants. The TG/DSC analysis indicated that MSWI fly ash sequestrated approximately 185 g CO₂/kg waste.

Key Words

Municipal solid waste incinerator (MSWI), Fly ash, Accelerated carbonation, CO₂ sequestration

권영현 Young-hyun Kwon , 손준익 Jun-ik Son , 김기헌 Ki-heon Kim

DOI:10.9786/kswm.2016.33.5.505

Abstract

The lower heating value is the basic unit to calculate annual energy in estimating an energy gain factor. Reliability of an energy gain factor depends on the accuracy of the lower heating value. However, the deviation of heating value is large, and there is no common standard. Thus, the present methods of estimating the lower heating value (calorimeter method, ultimate analysis method, etc.) are inferior in accuracy. Besides, the conventional estimation method cannot reflect the waste`s inhomogenous properties or seasonal effect. Hence, this study estimated the lower heating value on the basis of relation between heat input and heat output in equilibrium state by using the law of conservation of energy and the first law of thermodynamics for industrial waste incineration facilities (57 facilities) currently in operation. In the case of self-contained boilers, the lower heating value was an average of kcal/kg (1,984-6,476 kcal/ kg), and in case of separable boilers, the lower heating value was estimated to be an average of 3,787 kcal/kg (1,621- 486 kcal/kg).

Key Words

Incineration heat, Lower heating value, Heat balance, Industrial waste incineration

박승철 Seung-cheol Park , 조환성 Hwan-seong Cho , 정진도 Jin-do Chung

DOI:10.9786/kswm.2016.33.5.513

Abstract

This study examined oyster shells on a laboratory scale to determine whether they could be used as a replacement for limestone (PCC: precipitated calcium carbonate) as a filler in the paper production process. The optimum PCC production conditions and phase conversion rate at laboratory scale and 10 kg pilot plant scale were compared. For the phase conversion rate of CaO, 86.4% of the oyster shell and 55.6% of the limestone were converted. 80.4% of 86.4% CaO from the oyster shell and 52.0% of 55.6% CaO from the limestone were converted to Ca(OH)₂. 99.6% of the oyster shell Ca(OH)₂ and 100% of the limestone Ca(OH)₂ were converted to PCC at laboratory scale. Meanwhile, the PCC phase conversion rate of oyster shells using the pilot plant was found to be 96.2%. To examine the potential for com-mercialization, PCC made of oyster shells was used in paper factories H and M for the applicable tests. As a result, the tensile strength, elongation, and internal bond strength of the product using the PCC from the oyster shells were similar to those of the product of paper factory H. However, approximately 2% reduction in bulk, 2% reduction in whiteness, and 0.3% reduction in opacity were reduced in paper factory H. For the product of paper factory M, the pH of 12.5 exceeds the KS standard, and the viscosity and residue are significantly higher than those of the product paper factory M. This study showed that the PCC phase conversion rate for oyster shells is higher than that for limestone under the conditions of PCC manufacturing at laboratory and pilot plant scales. The PCC whiteness test results of 99% for the pilot plant PCC, 97% for the lab scale PCC, and 93% for the limestone PCC illustrate that oyster shells are a useful material for manufacturing PCC. Because each process requires different physical properties and particle conditions, although the same PCC obtained from the oyster shells was used in both factories, it was applicable in paper factory H but not in paper factory M. Therefore, in order to examine applicability of the oyster shell-derived PCC for paper manufacturing processes, additional research is required on the adjustment of the physical properties standard and uniformity particle.

Key Words

Oyster shell, Lime stone, Precipitated calcium carbonate, PCC, Recycling

윤현명 Hyunmyeong Yun , 황연정 Yeonjung Hwang , 장용철 Yong-chul Jang , 이소라 Sora Yi

DOI:10.9786/kswm.2016.33.5.521

Abstract

In recent years, waste-to-energy conversion using municipal solid waste (MSW) has been gaining attention in municipalities. Such conversion can reduce the dependency of non-renewable energy such as fossil fuels by generating solid refuse fuel (SRF) and diverting landfilling of the waste, although there is debate over the efficiency and economic aspect of the practice. With a growing interest in the conversion, D city is trying to adopt all possible measures towards achieving a material-cycle society by constructing a waste-to-energy town by 2018. The waste-to-energy town will be comprised of energy recovery facilities such as a mechanical treatment facility for fluff-type SRF with a power generation plant, and anaerobic digestion of food waste for biogas recovery. In this paper, we focus on estimating the energy recovery potentials and greenhouse gas (GHG) reduction of MSW by waste-to-energy conversion under three different scenarios. The data required for this study were obtained from available national statistics and reports, a literature review, and interviews with local authorities and industry experts. The lower heating value was calculated using the modified Dulong equation. Based on the results of this study, the energy recovery potential of MSW was calculated to be approximately 14,201-51,122 TOE/y, 12,426-44,732 TOE/y, and 8,520-30,673 TOE/y for Scenarios 1, 2, and 3, respectively. The reduction of GHG by such conversion was estimated to range from 10,074-36,938 tonCO₂eq/y, depending on scenario. This study would help determine the production rate of fluff-type SRF to be converted into a form of energy. In addition, this study would aid waste management decision-makers to clarify the effectiveness of recycling of MSW and their corresponding energy recovery potentials, as well as to understand GHG reduction by the conversion.

Key Words

Municipal solid waste, Solid refuse fuel, Energy recovery, GHG