• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.647-653
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• 2012

We have investigated the kinetics and activity of waste catalysts for steam-lignite gasification. Waste catalysts I, II, III and reference $K_2CO_3$ were used and physical mixed with a coal. The gasification experiments were carried out with the low rank coal loaded with 1 wt% and 5 wt% catalyst at the temperature range from 700 to $900^{\circ}C$ using thermobalance reactor. It was observed that the carbon conversion reached almost 100% regardless of the kinds of catalysts at $900^{\circ}C$. The shortest time to reach the designated conversion was obtained for 1 wt% waste catalyst II and 5 wt% $K_2CO_3$ at $900^{\circ}C$. The gasification reaction rate constant increased with increasing the temperature. Highest rate constant was obtained with $K_2CO_3$ at $900^{\circ}C$. The lowest activation energy was 69.42 kJ/mol for 5 wt% waste catalyst II. The waste catalyst had an influence on the reduction of activation energy.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.699-706
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• 2022

Recently, hydrogen production is attracting attention. In this study, a process simulation was conducted on the gasification reaction to produce hydrogen using rice husks, which are produced as by-products of rice. For this purpose, Chuchung, Odae, and Dongjin rice, which are rice varieties produced in Korea, were compared with the literature. The Korean rice contained more hydrogen and less oxygen compared to the literature. As a result of the simulation, large amounts of H₂ and CH₄ and small amounts of CO₂ and CO were produced accordingly. The conditions to maximize hydrogen production were a gasification reaction temperature of 700℃ and an Steam-to-Biomass (S/B) ratio of 0.4-0.6. However, because the S/B ratio is related to the gasification catalyst degradation, the model needs to be improved through additional experiments in the future. This study showed the possibility of hydrogen production using Korean rice husks, which had not been reported.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.37-40
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• 2012

In an entrained flow coal gasifier, predicting the reaction behavior of pulverized coal particles requires detailed information on devolatilization, char gasification, gaseous reactions, turbulence and heat transfer. Among the input parameters, the rate of devolatilization and the composition of volatile species are difficult to determine by experiments due to a high pressure (~40 bar) and temperature (${\sim}1500^{\circ}C$). This study investigates the effect of devolatilization models on the reaction and heat transfer characteristics of a 300 MWe Shell coal gasifier. A simplified devolatilization model and advanced model based on Flashchain were evaluated, which had different volatiles composition and devolatilization rates. It was found that the tested models produce similar flow and reaction trends, but the simplified model slightly over-predict the temperature and wall heat flux near the coal inlets.

• 자원리싸이클링
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• 제30권6호
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• pp.12-18
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• 2021

수성가스 전환 반응은 가스화로 생성된 합성 가스에 수소 생산 증가와 H₂/CO 비율 제어를 위해 수증기를 첨가하는 가스화 후속 공정이다. 본 연구에서는 RPF(Refuse plastic fuel) 가스화 시스템의 합성가스를 대상으로 수성가스 전환 반응을 연구하였다. 수성가스 전환 반응은 촉매를 이용하여 high temperature shift(HTS) 와 low temperature shift(LTS) 반응에 대하여 lab scale 관형 반응기를 이용하여 반응 온도, steam/carbon ratio, 유량의 변화가 H₂ 생성과 CO 전환율에 미치는 영향을 조사하였다. 운전 온도는 HTS 시스템이 250-400℃, LTS 시스템이 190-220℃이며 steam/carbon ratio는 1.5-3.5로 변화시켰다. 반응 모의 가스의 농도는 RPF 합성가스의 농도를 기준으로 CO, 40vol%, H₂, 25vol%, CO₂, 25vol%이다. 반응 온도와 steam/carbon ratio가 증가함에 따라 CO 전환율 및 H₂ 생성량이 증가하고, 유량이 증가하면 촉매층의 체류시간 단축으로 CO 전환율과 H₂ 생성량이 감소하였다.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.693-701
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• 2016

Steam gasification of low rank coals is possible at relatively low temperature and low pressure, and thus shows higher efficiency compared to high rank coals. In this study, the gasification reactivity of four different Indonesian low rank coals (Samhwa, Eco, Roto, Kideco-L) was evaluated in $T=700-800^{\circ}C$. The low rank coals containing $53.8{\pm}3.4$ wt% volatile matter in proximate analysis and $71.6{\pm}1.2$ wt% carbon in ultimate analysis showed comparable gasification reactivity. In addition, $K_2CO_3$ catalyst rapidly accelerated the reaction rate at $700^{\circ}C$, and all of the coals were converted over 90% within 1 hour. The XRD analysis showed no significant difference in carbonization between the coals, and the FT-IR spectrum showed similar functional groups except for differences due to moisture and minerals. TGA results in pyrolysis ($N_2$) and $CO_2$ gasification atmosphere showed very similar behavior up to $800^{\circ}C$ regardless of the coal species, which is consistent with the steam gasification results. This confirms that the indirect evaluation of the reactivity can be made by the above instrumental analyses.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.425-434
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• 2010

Integrated gasification combined cycle (IGCC) is an efficient and environment-friendly power generation system which is capable of burning low-ranked coals and other renewable resources such as biofuels, petcokes and residues. In this study some process modeling on a conceptual entrained flow gasifier was conducted using the ASPEN Plus process simulator. This model is composed of three major steps; initial coal pyrolysis, combustion of volatile components, and gasification of char particles. One of the purposes of this study is to develop an effective and versatile simulation model applicable to numerous configurations of coal gasification systems. Our model does not depend on the hypothesis of chemical equilibrium as it can trace the exact reaction kinetics and incorporate the residence time calculation of solid particles in the reactors. Comparisons with previously reported models and experimental results also showed that the predictions by our model were pretty reasonable in estimating the products and the conditions of gasification processes. Verification of the accuracy of our model was mainly based upon how closely it predicts the syngas composition in the gasifier outlet. Lastly the effects of change oxygen are studied by sensitivity analysis using the developed model.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1015-1020
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• 2012

석탄 및 pet coke (petroleum coke)는 그 이용이 제한적이지만 공급이 풍부한 에너지원이므로, 가스화공정에 적용하여 고급연료인 수소나 액체연료를 생산할 수 있다. 본 연구에서는 열천칭반응기와 실험실규모의 유동층반응기(내경 0.02 m, 높이 0.6 m)에서 갈탄, 무연탄, pet coke의 수증기 가스화 반응특성을 조사하였다. 가스화 온도 $600{\sim}900^{\circ}C$, 수증기 분압 0.15~0.95 atm 및 수증기/연료 비의 조업변수가 가스화반응속도 및 생성가스의 발열량에 미치는 영향을 조사하였다. 기체-고체 반응모델로서 modified volumetric reaction model을 적용하여 가스화반응의 거동을 묘사하고 kinetic 인자들을 도출하였다. 가스화 반응온도가 높을수록 생성가스 중의 수소농도와 가스의 발열량은 증가하였다. 생성가스 발열량은 무연탄 > 갈탄 > pet coke의 순으로 높게 나타났는데, 반응온도 $900^{\circ}C$, 수증기분압 95%의 조건에서 10.0 > 6.9 > 5.7 $MJ/m^3$로 각각 얻어졌다. 본 연구를 통하여 갈탄과 pet coke에 대해 가스화공정의 잠재적인 연료로서의 가능성을 확인하였다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 춘계 학술발표회 논문집
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• pp.23-31
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• 1999

가압 조건하에서의 석탄가스화 특성을 규명하기 위해, 온도, 압력, 산소/석탄비, 수증기/석탄비 등을 변화시켜가며 로토탄(Sub A)에 대하여 PDTF(Pressurized drop tube furnace) 실험을 수행하였다. 실험결과, 상압 조건에서보다 가압조건에서의 가스화가 탄소 전환율과 냉가스효율의 측면에서 더 유리한 것으로 측정되었다. 최대의 냉가스효율을 보이는 산소/석탄비(무게기준)는 0.5∼0.7(g/g)로 측정되었고, 온도가 충분히 높은 경우에만 수증기/석탄비의 증가가 냉가스효율의 증가를 가져왔다. 압력이 증가할수록 열분해에 의한 탄소전환의 비중은 감소하고 대신 기고반응(heterogeneous reaction)에 의한 탄소전환의 비중이 증가하였다.

• 한국연소학회지
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• 제22권4호
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• pp.19-26
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• 2017

This study investigates the gasification of coal char by $CO_2$ under high pressures in a drop tube furnace(DTF). The rate constants are derived for the shrinking core model using the conventional method based on the set reactor conditions. The computational fluid dynamic(CFD) simulations adopting the rate constants revealed that the carbon conversion was much slower than the experimental results, especially under high temperature and high partial pressure of reactants. Three reasons were identified for the discrepancy: i) shorter reaction time because of the entry region for heating, ii) lower particle temperature by the endothermic reaction, and iii) lower partial pressure of $CO_2$ by its consumption. Therefore, the rate constants were corrected based on the actual reaction conditions of the char. The CFD results updated using the corrected rate constants well matched with the measured values. Such correction of reaction conditions in a DTF is essential in deriving rate constants for any char conversion models by $H_2O$ and $O_2$ as well as $CO_2$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.75.1-75.1
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• 2011

Coal gasification is considered as one of the most prospective technologies in energy field since it can be utilized for various products such as electricity, SNG (Synthetic Natural Gas or Substitute Natural Gas) and other chemical products. Among those products from coal gasification, SNG is emerging as a very lucrative product due to the rising prices of oil and natural gas, especially in Asian countries. The process of SNG production is very similar to the conventional IGCC in that the overall process is highly dependent on the type of gasifier and coal rank. However, there are some differences between SNG production and IGCC, which is that SNG plant requires higher oxygen purity from oxygen plant and more complex gas cleanup processes including water-gas shift reaction and methanation. Water-gas shift reaction is one of the main process in SNG plant because it is a starting point for the latter gas cleanup processes. For the methanation process, syngas is required to have a composition of $H_2$/CO = 3. This study reviewed various considerations for water-gas shift process in a conceptual design on an early stage like a feasibility study for a real project. The factors that affect the design parameters of water-gas shift reaction include the coal properties, the type of gasifier, the overall thermal efficiency of the plant and so on. Water-gas shift reaction is a relatively proven technology compared to the other processes in SNG plant so that it can reduce technological variability when designing a SNG project.