• 한국환경과학회지
• /
• 제19권1호
• /
• pp.9-16
• /
• 2010

This pilot study evaluated fueling feasibility of sewage sludge, which contains a large amount of water content, by applying melting of thermoplastic polyethylene (PE). This study has identified a simultaneous achievement of drying and heating value improvement of the sewage sludge. The sewage sludge collected from a sewage sludge treatment plant during a winter period had a water content of 83.7 wt%, a combustible volatile content of 12.5 wt%, and an ash content of 3.8 wt%. The higher heating value (HHV) of the dried sewage sludge, before impregnation or coating of PE, was 4,600 kcal/kg. The collected sewage sludge was immersed into the melted PE solution, which had a HHV of 11,070 kcal/kg, and kept immersing with increasing reaction time. As the reaction (immersing or coating or impregnation) time increased, the water content of the sludge decreased. However, the HHV of the sludge increased with increasing the reaction time. The HHVs of the sewage sludge immersed or dipped into the melted PE solution for 15 min ranged from 6,780 to 8,170 kcal/kg with water content less than 7 wt%. This result indicates the melted PE solution can be utilized as an improvement technology for dryness and heating value of the sewage sludge with high water content. The sewage sludge impregnated or coated with melted PE can be utilized as potential fuel or energy resources.

• 한국안전학회지
• /
• 제32권1호
• /
• pp.27-32
• /
• 2017

The experimental design methodology was applied in the real scale coal-fired boiler to predict the various combustion properties according to the operating conditions and to assess the coal plant safety. Response surface method (RSM) was introduced as a design of experiment, and the database for RSM was provided with the numerical simulation of the coal-fired boiler. The three independent variables, high heating value of coal (HHV), overall stoichiometry excess air ratio (OST), and burner-side stoichiometry excess air ratio (BST), were set to characterize the cross section averaged NOx concentration and temperature distribution. The maximum NOx concentration was predicted accurately and mainly controlled by BST in the boiler. The parabola function was assumed for the zone averaged peak temperature distribution, and the prediction was in a fairly good agreement with the experiments except downstream. Also, the location of the peak temperature was compared with that of maximum NOx, which implies that thermal NOx formation is the main mechanism in the coal-fired boiler. These results promise the wide use of statistical models for the fast prediction and safety assessment.

• 한국연소학회지
• /
• 제18권3호
• /
• pp.44-53
• /
• 2013

In this study, the economic evaluation for imported coals was conducted for power plant based on thermo-dynamical performance analysis. The number of coal types considered was 1,755 imported by five power generation companies in Korea during the 2010-2012. The higher heating value (HHV) of the coals ranged 4,000-6,500 kcal/kg, mostly sub-bituminous. The 1D thermo-dynamical performance modeling was performed for a 500 MWe standard power plant using PROATES code. It was founded that the low rank coals had negative effects on the plant efficiency mainly due to the increased heat loss by moisture, hydrogen and flue gas. Based on the performance analysis, the economic performance of the coals was evaluated. The apparent price of low-rank coals tended to be significantly lower than design coal; for example, the unit price of coal with a HHV of 4,000 kcal/kg was 57% of the reference coal having 6,080 kcal/kg. Considering the negative effects leading to a decrease in the thermal performance, heating value compensation, and increased parasite load, the corrected unit cost for the coal with 4,000 kcal/kg was 90.7% of the reference coal. Overall, the cost saving by imported coals was not high as expected.

• Journal of the Korean Wood Science and Technology
• /
• 제40권6호
• /
• pp.445-453
• /
• 2012

본 연구에서는 백합나무의 급속 열분해 공정에서 시료의 입자크기 및 함수율 조건이 열분해 산물(가스, 바이오오일, 바이오촤)의 수율과 물리 화학적 특성에 미치는 영향을 구명하였다. 시료의 함수율이 낮을수록 바이오오일의 수율은 증가하였으며 시료의 입자 크기는 수율 변화에 큰 영향을 미치지 않았다. 각 조건별로 생성된 바이오오일은 20~30%의 수분 함량과 pH 2.2~2.4, 발열량 16.6~18.5 MJ/kg의 수준을 나타내었으며 바이오오일 내 수분 함량은 높은 함수율 시료 조건에서 증가하는 것을 확인하였다. 바이오촤의 경우 80% 이상이 탄소로 이루어져있으며 발열량은 26.2~30.1 MJ/kg 수준으로 측정되었다.

• Journal of Biosystems Engineering
• /
• 제43권1호
• /
• pp.14-20
• /
• 2018

Purpose: The purpose of this study was to investigate the performance of a vacuum pyrolysis system, to analyze bio-oil characteristics, and to examine the applicability for farm-scale capacity. Methods: The biomass was pyrolyzed at 450, 480, and $490^{\circ}C$ on an electric heat plate in a vacuum reactor. The waste heat from the heat exchanger of the reactor was recycled to evaporate water from the bio-oil. The chemical composition of the bio-oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Results: According to the analysis, the moisture content (MC) in the bio-oil was approximately 9%, the high heating value (HHV) was approximately 26 MJ/kg, and 29 compounds were identified. These 29 compounds consisted of six series of carbohydrates, 17 series of lignins, and six series of resins. Conclusions: Owing to low water content and the oxygen content, the HHV of the bio-oil produced from the vacuum reactor was higher by about 6 MJ/kg than that of the bio-oil produced from a fluidized bed reactor.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
• /
• pp.131-134
• /
• 2015

국내 천연가스 열량제도를 현행 표준 열량제 $10,400kcal/Nm^3(43.54MJ/Nm^3)$에서 중간 조정기간을 두고 2012.07.01부터는 최저 $10,100kcal/Nm^3(42.28MJ/Nm^3)$을 유지하고 2015년 이후 $9,800(41.1MJ/Nm^3){\sim}10,600kcal/Nm^3(44.4MJ/Nm^3)$ 열량범위제도로 변경 추진되고 있다. 산업현장에서 열량변동을 측정하여 공연비 제어기술을 개발하고자 60ton Al 용해로에 열량대응기술 개발을 위한 내용으로 열량측정시스템설치 및 열량 값과 연계하여 공연비 제어기술개발연구 내용으로 결과는 다음과 같다. 단순히 표준열량으로 에 맞춰 프로그램된 제어로직에 열량변동에서 검출된 신호를 이용하여 연료보정 값을 추가한 로직을 재구성할 필요가 있다. 이 혀장의 경우는 용탕의 온도가 목표온도 근처까지 올리기가 어려워진 상황으로 주로 공급열량 저열량화에 따른 과잉공기영향으로 온도상승이 어려워 보이며 적절한 공연비로 최적화 되면 이러한 문제가 개선되리라 생각된다.

• 신재생에너지
• /
• 제10권2호
• /
• pp.12-18
• /
• 2014

The objective of this work is to produce solid biofuel from sawdust using the HTC (Hydrothermal carbonization) process. The HTC process of feedstock involves the raw material coming into contact with high temperature and pressurized water. The HTC process could produce gaseous, liquefied and solid products, but this study focused on solid product only as an alternative to coal. In this study, sawdust used for a feedstock and its moisture content was under 5%. Water was added with the feedstock to raise moisture content to 80% and also used catalysts. The HTC process was performed at temperature range from 200 to $270^{\circ}C$ and reaction time was 15 to 120 min. Rising temperature resulted in increasing the higher heating value (HHV) of HTC product. In case of adding catalyst, HHV of solid biofuel was higher and reaction occurred at lower temperature and pressure. Also, HTC solid product had been characterized and found to be hydrophobic, increased HHV (over 40%), and pelletized easily compared to raw material.

• KEPCO Journal on Electric Power and Energy
• /
• 제2권3호
• /
• pp.447-452
• /
• 2016

It is imperative to develop an effective pathway to depolymerize lignin into liquid fuel that can be used as a bioheavy oil. Lignin can be converted into liquid products either by a solvent-free thermal cracking in the absence air, or thermo-chemical degradation in the presence of suitable solvents and chemicals. Here we show that the solvent-assisted liquefaction has produced promising results in the presence of metal-based catalysts. The supercritical ethanol is an efficient liquefaction solvent, which not only provides better solubility to lignin, but also scavenges the intermediate species. The concentrated sulfuric acid hydrolysis lignin (CSAHL) was completely liquefied in the presence of solid catalysts (Ni, Pd and Ru) with no char formation. The effective deoxy-liquefaction nature associated with scEtOH with aid hydrodeoxygenation catalysts, resulted in significant reduction in oxygen-to-carbon (O/C) molar ratio up to 61%. The decrease in oxygen content and increase in carbon and hydrogen contents increased the calorific value bio-oil, with higher heating value (HHV) of $34.6MJ{\cdot}Kg^{-1}$. The overall process is energetically efficient with 129.8% energy recovery (ER) and 70.8% energy efficiency (EE). The GC-TOF/MS analysis of bio-oil shows that the bio-oil mainly consists of monomeric species such as phenols, esters, furans, alcohols, and traces of aliphatic hydrocarbons. The bio-oil produced has better flow properties, low molecular weight, and high aromaticity.

• Journal of the Korean Wood Science and Technology
• /
• 제48권2호
• /
• pp.181-195
• /
• 2020

본 연구는 평로탄화로 이용한 성형목탄 제조과정에서 얻은 탄화된 바이오매스의 특성을 분석하였으며, 기계적 전처리 및 평로탄화로 내 위치에 따른 특성 차이를 비교하고자 하였다. 성형목탄 제조업체에서 채취된 바이오매스 1종과 탄화 바이오매스 5종의 시료를 대상으로 선별(screening) 및 분쇄(grinding)를 통해 분석시료의 입자크기 범위별로 분류한 후, 고정탄소, 회분, 휘발성 화합물, 원소 함량, 발열량을 측정하였다. 실험 결과, 평로탄화로의 위치에 따라서는 중간층의 탄화 바이오매스 발열량이 20.4 MJ/kg으로 가장 높은 연료적 특성을 나타내었다. 선별 입자 크기에 따라서는 100 mesh 이하의 탄화 바이오매스에서 회분함량이 가장 낮았고 발열량, 탄소 함량, 고정탄소 함량은 높았다. 상관관계 분석 결과 회분 함량은 발열량, 휘발성화합물, 고정탄소, 탄소 함량과 모두 음의 상관관계를 나타내어 회분 함량이 연료적 특성에 부정적인 영향을 미치는 것을 확인하였다.

• 공업화학
• /
• 제25권5호
• /
• pp.510-514
• /
• 2014

본 연구에서는 고형연료로써의 에너지 잠재성을 평가하기 위하여 하수슬러지의 기본특성에 대한 반탄화의 영향을 고찰하였으며, 이를 위하여 $150{\sim}600^{\circ}C$의 온도조건에서 하수슬러지의 반탄화 실험을 수행하였다. 반탄화된 하수슬러지는 에너지 수율, 회분, 가연분 및 고위발열량에 의하여 분석되었으며, 반탄화 과정에서 발생되는 가스성분 또한 분석하였다. 또한 본 연구에서는 하수슬러지의 반탄화 반응에 대한 속도론적 해석을 위하여 열중량 분석을 수행하였다. 본 연구로부터 반탄화 온도가 증가함에 따라 회분함량은 증가하는 반면에 에너지 수율, 고위발열량 및 가연분은 감소하는 것으로 나타났으며, 또한 $300^{\circ}C$에서 하수슬러지 내에 함유된 가연성 성분의 열분해로 인하여 일산화탄소 및 탄화수소 가스가 발생하기 시작함을 확인할 수 있었다.