• 한국연소학회지
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• 제21권4호
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• pp.23-29
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• 2016

Reactivity of gasification defined by bouardard reaction is critical parameter in efficiency of the gasifier. In this study, char reactivity of the gasification was derived from the experiments using the intrinsic reaction kinetics model. Pressurized wire mesh heating reactor (PWMR) can produce high temperature and high pressure conditions up to 50 atm and 1750 K, respectively and PWMR was designed to evaluate the intrinsic reaction kinetics of $CO_2$ gasification. In this study, Kideco and KCH (sub-bituminous Indonesian coal) were pulverized and converted into char. Experiments used the PWMR were conducted and the conditions of the temperature and pressure were 1373~1673 K, 1~40 atm. To distinguish the pressure effect from high pressurized condition, internal and external effectiveness factors were considered. Finally, the intrinsic kinetics of the Kideco and KCH coal char were derived from $n^{th}$ order reaction rate equations.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.328-339
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• 2010

A new gasification model for coal char was developed considering the effects of pore structure and solid reaction product (ash) and compared with conventional models. Among various parameters reflecting microscopic pore structure, initial pore surface per unit volume of char was found to have the largest effect on carbon conversions. Reaction studies showed that the proposed model can predict carbon conversion more accurately over a broader range of reaction degree compared to the conventional models. Therefore the model proposed in this study would be useful for the design of pilot or commercial scale gasifiers.

• 한국연소학회지
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• 제16권1호
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• pp.8-14
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• 2011

Biomass gasification is a promising technology in terms of clean energy and flexible options for end use such as heat, steam, electricity, gaseous or liquid fuels. In a gasification process, reduction of tar is very important because it can cause any mechanical problems and small tar implies high energy efficiency. However, generation and conversion mechanisms of tar have not been fully understood due to its complex nature. In this study, characteristics of tar generated from different gasification stages were investigated. Korean pine woodchip was used as feedstock and tar was sampled in a separate way during devolatilization and char gasification stage, investigated. As a result. more various kinds of hydro carbon compounds were identified in the devolatilization stage than char gasification stage because primary tar compounds are released mostly from pyrolysis of cellulose and hemicellulose. When the reaction temperature increased up to $900^{\circ}C$, tar composition becomes simplified into about 10 aromatic compounds mostly with 1-4 rings without substitution up to phenanthrene. The sampled tar in the char gasification stage mostly contains 5-7 simple aromatic compounds.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.493-499
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• 2013

저급탄의 가스화에서 얻은 비산재를 활용하기 위한 목적으로 비산재의 열분해와 비산재 촤의 $CO_2$ 가스화반응에 대한 실험을 비등온의 승온 조건(10, 20, $30^{\circ}C$/min)에서 TGA를 이용하여 수행하였다. 비산재의 열분해 속도는 1차의 열분해 모델(Kissinger법)에 의해 해석하였지만, 비산재에 포함된 휘발분의 함량이 낮아 모델의 신뢰도는 낮게 평가되었다. 비산재 촤의 $CO_2$ 가스화반응에 대한 실험결과는 미반응핵 모델, 균일반응 모델 및 랜덤 기공 모델 등으로 해석하여 석탄 촤의 $CO_2$ 가스화반응 결과와 비교하였다. 저탄소가 함유된 비산재 촤(LG탄)는 200.8 kJ/mol의 활성화 에너지로 균일반응 모델의 의해 잘 모사되었으며, 고탄소가 함유된 비산재 촤(KPU탄)의 경우에는 198.3 kJ/mol의 활성화 에너지로 석탄 촤의 $CO_2$ 가스화 특성과 유사하게 랜덤 기공 모델의 의해 잘 모사되었다. 결과로서, 두 비산재 촤의 $CO_2$ 가스화반응에 대한 활성화 에너지는 큰 차이를 나타내지는 않았지만, 고정탄소의 함량에 따라 적용할 수 있는 모델이 다르다는 것을 확인할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.33-36
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• 2014

Gasification of biomass produces syngas containing CO, $H_2$ and/or $CH_4$, which can then be converted into energy or value-added fuels. One of key issues for efficient gasification is to minimize tar concentration in the syngas for use in a final conversion device such as gas engine. This study investigated the decomposition of primary tar by catalytic cracking using char as catalyst, of which the feature can be integrated into a fixed bed gasifier design. The pyrolysis vapor containing tar from pyrolysis of wood at $500^{\circ}C$ was passed through a reactor filled with or without char at $800^{\circ}C$ for a residence time of 1, 3 or 5 sec. Then, the condensable vapor (water and tar) and gases were analyzed for the yields and elemental composition. Four types of char particles with different microscopic surface area and pore size distribution: wood, paddy straw, palm kernel shell and activated carbon. The results were analyzed for the mass and carbon yields of tar and the composition of product gases to conclude the effects of char types and residence time.

• 청정기술
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• 제19권3호
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• pp.306-312
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• 2013

드레이톤 탄으로부터 제조된 차(char)의 $850^{\circ}C$ 등온조건 가스화 반응에서 반응기체인 이산화탄소-질소 혼합기체의 이산화탄소 농도가 반응속도에 미치는 영향에 대해 알아보았다. 저온 가스화 반응성을 높이기 위해 탄산칼륨을 사용하였다. 이산화탄소의 농도가 증가할수록 차-이산화탄소(char-$CO_2$) 가스화 반응성은 좋으며 전환율 증가 속도는 고농도에서는 일정하게 유지되었다. 가스화 반응성은 증가하였으며, 70% 이상의 고농도 조건에서는 일정하게 유지되었다. 기-고체 반응모델 중에서 shrinking core model (SCM)과 shrinking core model (SCM), modified volumetric reaction model (MVRM)을 비교하였다. 선형 회귀를 통해 얻은 상관계수 값은 저농도에서는 SCM이 VRM보다 높은 반면, 고농도에서는 VRM이 SCM보다 높은 값을 보였다. 모든 농도에서 MVRM의 상관계수 값은 다른 모델들 보다 가장 높은 값을 보였다.

• 한국수소및신에너지학회논문집
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• 제22권3호
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• pp.386-401
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• 2011

Mathematical models for various steps in coal gasification reactions were developed and applied to investigate the effects of operation parameters on dynamic behavior of gasification process. Chemical reactions considered in these models were pyrolysis, volatile combustion, water shift reaction, steam-methane reformation, and char gasification. Kinetics of heterogeneous reactions between char and gaseous agents was based on Random pore model. Momentum balance and Stokes' law were used to estimate the residence time of solid particles (char) in an up-flow reactor. The effects of operation parameters on syngas composition, reaction temperature, carbon conversion were verified. Parameters considered here for this purpose were $O_2$-to-coal mass ratio, pressure of reactor, composition of coal, diameter of char particle. On the basis of these parametric studies some quantitative parameter-response relationships were established from both dynamic and steady-state point of view. Without depending on steady state approximation, the present model can describe both transient and long-time limit behavior of the gasification system and accordingly serve as a proto-type dynamic simulator of coal gasification process. Incorporation of heat transfer through heterogenous boundaries, slag formation and steam generation is under progress and additional refinement of mathematical models to reflect the actual design of commercial gasifiers will be made in the near futureK.

• Environmental Engineering Research
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• 제24권4호
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• pp.591-599
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• 2019

To convert sewage sludge to energy, drying-gasification characteristics during microwave heating were studied. During the gasification of carbon dioxide, the main products were gas, followed by char, and tar in terms of the amount. The main components of the producer gas were carbon monoxide and hydrogen including a small amount of methane and light hydrocarbons. They showed a sufficient heating value as a fuel. The generated tar is gravimetric tar, which is total tar. As light tars, benzene (light aromatic tar) was a major light tar. Naphthalene, anthracene, and pyrene (light polycyclic aromatic hydrocarbon tars) were also generated, but in relatively small amounts. Ammonia and hydrogen cyanide (precursor for NO_x) were generated from thermal decomposition of tar containing protein and nitrogen in sewage sludge. In the case of sludge char, its average pore diameter was small, but specific area, pore volume, and adsorption amounts were relatively large, resulting in superior adsorption characteristics.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.746-754
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• 2015

본 연구는 이온교환법을 통해 Ni촉매를 담지한 저등급 석탄(인도네시아 Eco탄)과 바이오매스(대한민국 상록수)의 혼합물로부터 제조된 촤(char)를 $700{\sim}900^{\circ}C$ 등온조건에서 온도가 반응속도에 미치는 영향에 대해 알아보았다. $Char-CO_2$ 가스화 반응은 700, 750, 800, 850, $900^{\circ}C$의 온도에서 진행하였으며, 기-고체 반응의 가스화 거동특성을 알아보기 위하여 각각 다른 가정을 갖고 있는 shrinking core model(SCM), volumetric reaction model(VRM), random pore model(RPM), modified volumetric reaction model(MVRM)을 실험결과에 적용하여 비교하였다. Arrhenius equation를 이용하여 Ni-coal/biomass와 Non-catalyst coal/biomass의 활성화에너지를 구하였고 이를 비교하였다.

• 한국수소및신에너지학회논문집
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• 제27권2호
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• pp.192-200
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• 2016

A characteristics of microwave drying-gasification was analyzed for converting a dewatered sewage sludge generated a wastewater treatment plant. Gas (60%) was the largest component of the product of microwave gasification, followed by sludge char (33%) and tar (2%). The main components of the producer gas were hydrogen (33%) and carbon monoxide (40%), and there was some methane and hydrocarbons ($C_2H_4$, $C_2H_6$, $C_3H_8$). Larger nitrogen and smaller oxygen amounts were generated. Gravimetric tar generated $414g/m^3$. This means a total tar which is a heavy hydrocarbons from the volatile organic substance in the sewage sludge. Selected light tars were benzene, anthracene, naphthalene, pyrene, showing lower concentrations as 2.62, 0.37, 0.49, $0.28g/m^3$, respectively. Sludge char has larger meso pores which is a mean pore size of $50.85{\AA}$ and has high adsorptivity. An amount of adsorption was $228.71cm^3/g$, showing higher quantity than acommercial adsorbers. This indicates that the gas obtained from the microwave gasification of wet sewage sludge can be used as fuel, but the heavy tar in the gas must be treated. Sludge char can be used as a tar reduction adsorbent in the process, and then burns as a solid fuel.