• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.7
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• pp.895-904
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• 2001

Flow fields, temperature distributions, and particle trajectories in a 2-stage entrained-flow gasifier are calculated using a CFD code, FLUENT. Realizable k-$\xi$ model is used as a turbulent model. Because of swirling flow there appear recirculation regions near the burners. The characteristics of flow fields and temperature distributions in the gasifier are dependent on the swirl number of the system. Mean residence time of the particles in the reductor is inversely proportional to particle size, particle density and swirl number. As the swirl number is increasing, the particles injected from the combustor burners approach the wall near the combustor burners, which prevents the particles from entering the reductor and thus attatching the reductor wall. If the lower combustor burner angle is larger than the higher combustor burner angle for a given swirl number, the particles may move toward the reductor and cause ash/slag deposition problem.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.453-456
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• 2007

감압 증류 후 생성되는 중질유의 고도화를 위하여 코킹 공정을 거친 후 정유 부산물로 생성되는 열적으로 매우 안정하고, 높은 발열량을 갖는 반면 황, 바나듐 함량이 높은 석유코크스의 효과적인 이용을 위하여 본 연구에서는 가스화 공정을 적용하였다. 1T/D 용량의 분류층 가스화기를 이용하여 유연탄(drayton coal), 석유코크스, 또는 혼합한 경우의 가스화 성능을 알아보았으며, 각각의 경우에 대하여 비교하여 보았다. 높은 열 안정성을 갖는 석유코크스의 효과적인 가스화를 위하여 반응기 내 체류시간 및 버너 노즐 변경에 따른 가스화 성능 개선을 시도하였으며, 이때의 온도, 산소/원료 공급량 조건에 따른 생성가스 성분 및 탄소전환율, 냉가스효율 변화 특성을 알아보았다. 버너 노즐 구경 변경으로 인한 슬러리의 미립화를 통하여 향상된 탄소전환율 및 냉가스효율을 얻을 수 있었다.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1112-1120
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• 2002

Numerical investigations on air staging and fuel staging were carried out with a newly designed coaxial cyclone combustor, which uses the method of two stage coal combustion composed of pre-combustor and main combustor. The pre-combustor with a high air/fuel ratio is designed to supply gas at high temperature to the main combustor. To avoid local high temperature region in this process, secondary air is injected in the downstream. Together with the burned gas supplied from the pre-combustor and the preheated air directly injected into main combustor, coals supplied through the main burner react rapidly at a low air/fuel ratio. Strong swirling motion of cyclone combustor keeps the wall temperature high, which makes slagging combustion possible. Alaska, US coal is used for calculations. Predictions were made for various coal flow rates in the main combustor for fuel staging and for the various flow rate of secondary air in the pre-combustor for air staging. In-scattering angles are also chosen as a variable to increase residence times of coal particles. Temperature fields and particle trajectories for various conditions are described. Predicted temperature variations at the wall of the combustor are compared with corresponding experimental data and show a similar trend. The in-scattering angle of 20° is recommended to increase the combustion efficiency in the main chamber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.491-501
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• 2011

We performed numerical simulation using a DPM (discrete phase model) to identify the optimal operation ranges in two representative PM burners widely used in domestic 500-MW pulverized coal-fired power plants. Recently there has been an increased utilization of low-cost coals such as sub-bituminous coal. We investigate the effects of coal blends on the distribution ratio of coal to air by varying the mass flow rates of pulverized coal and primary air and the particle size. We present and discuss optimal conditions for the distribution ratio of coal to air in PM burners.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.23-31
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• 2017

Numerical study was conducted for the effects of various burner array on the workpiece and the gas temperature in a continuos reheating furnace. Under the same conditions which were the total heat of combustion, the heat capacity of unit burner, the number of burner and burner array were changed to be applied the furnace. The behavior of workpiece temperature and gas temperature in a furnace were evaluated for the effects as function of the changed conditions. A continuous reheating furnace designed for 110 tons/day of production capacity was applied in this study. The furnace which has several gas burners is designed to heat a workpiece. By this study, the better condition was confirmed than the existing designed condition.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.129-139
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• 2010

Coal gasification process, which had developed originally to convert coal from hydrogen and carbon monoxide, has used and developed in many countries because of environmental advantages such as carbon dioxide storage, decrease of pollutants and so on. Generally entrained-flow gasification process using pulverized coal under $75{\mu}m$ is used in Integrated Gas Combined Cycle(IGCC) because of easy scale up and high efficiency of energy conversion. Especially entrained-flow gasifers with coal water slurry have been used in many applications due to its fully developed technologies. In this paper, several technologies for coal-water slurry gasification that involves slurry preparation, burner, gasifier, slag melting and numerical simulation for plant design and operation were investigated. Entrained-flow gasification with coal water slurry can be used for synfuel production, SNG, chemicals as well as IGCC. To develop hybrid gasification process and use different types of coal, it is necessary to develop new technologies that will increase efficiency of the process.

• Plant Journal
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• v.15 no.3
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• pp.29-34
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• 2019

In the study, the effect of steam injection on syngas productivity was investigated under the constant operating conditions of gasifier oxygen load while the coal feed was fixed and the steam injection flow rate is changed in Taean IGCC plant. The maximum syngas average productivity was found to be at 80 % and 90 % of gasifier oxygen loads with the steam injection flow rate of 0.14 kg/s and 0.15 kg/s per coal burner. Through this study, the syngas productivity was changed by adjusting the steam injection amount and as the steam injection flow rate increased, the syngas productivity increased and then decreased again. The syngas productivity can be increased only by steam injection without supplying additional coal and it is considered that the syngas productivity has different characteristics depending on coal type. Thus it is recommended to operate the gasifier using Carbo-One coal with the steam injection flow rate of about 0.14 kg/s per coal burner when the gasifier oxygen load is 80 % ~ 90 %.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.1022-1030
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• 1999

A numerical study was carried out to analyze the effect of flow distribution of stirred part and plug flow part on combustion efficiency at the coal gasification process in an entrained bed coal reactor. The model of computation was based on gas phase eulerian balance equations of mass and momentum. The solid phase was described by lagrangian equations of motion. The $k-{\varepsilon}$ model was used to calculate the turbulence flow and eddy dissipation model was used to describe the gas phase reaction rate. The radiation was solved using a Monte-Carlo method. One-step parallel two reaction model was employed for the devolatilization process of a high volatile bituminous Kideco coal. The computations agreed well with the experiments, but the flame front was closer to the burner than the measured one. The flow distribution of a stirred part and a plug flow part in a reactor was a function of the magnitude of recirculation zone resulted from the swirl. The combustion efficiency was enhanced with decreasing stirred part and the maximum value was found around S=1.2, having the minimum stirred part. The combustion efficiency resulted from not only the flow distribution but also the particle residence time through the hot reaction zone of the stirred part, in particular for the weak swirl without IRZ(internal recirculation zone) and the long lifted flame.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.548-555
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• 2017

This study investigated the influence of air staging on combustion and NOx emission in a tangential-firing boiler at a 560 MWe capacity. For air staging, the stoichiometric ratio (SR) for the burner zone was varied from 0.995 to 0.94 while the overall value was fixed at 1.2. The temperature and heat flux in the burner zone and upper furnace corresponded to the distribution of SR, while the total boiler efficiency remained similar. The NOx emission at the furnace exit was reduced by up to 20% when the SR in the burner zone decreased to 0.94. However, the amount of unburned carbon and slagging propensity was not noticeably influenced by the changes in the SR of the burner zone. Therefore, it was favorable to lower the SR of the burner zone for reduction of NOx emission.

• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.103-108
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• 2004

The present paper relates to an apparatus in which all carbonaceous material such as coal, oil, plastics and any substance having carbon atoms as part of its constituents are reformed(gasified) into syngas at temperature above $1,200^{\circ}C$(KR patent No.0391121, and PCT/KR2001/01717 and PCT/KR2004/001020). It comprises a single-stage reforming reactor without catalyst and a syngas burner as shown in Fig.2. syngas is combusted with $O_2$ gas in the syngas bunter to produce $M_2O$ and $CO_2$ gas with exothermic heat. Reaction products are introduced into the reforming reactor, reaction heat from syngas burner elevate the temperature of reactor above $1,200^{\circ}C$, and reaction products reduce carbonaceous material down to CO and $H_2$ gases. Reactants and heat necessary for the reaction are provided through the syngas burner only, Neither $O_2$ gas nor steam are injected into the reforming reactor. Reformer is made of ceramic inner lining and sst outer casing. Multiple syngas burners may be connected to the reforming reactor in order to increase the syngas output, and a portion of the product syngas is recycled into syngas burner. The present reformer as shown in Fig.2 is suitable to gasify carbonaceous wastes without secondary pollutants formed from oxidation. Further, it can be miniaturized to accompany a fuel cell system as shown in Fig.3 The output syngas may be used to drive a fuel cell and a portion of electrical power generated in a fuel cell is used to heat a compact reformer up to $1,200^{\circ}C$ so that gas/liquid fossil fuel can efficiently reformed into syngas. The fuel cell serves as syngas burner in Fig.2. The reformation reaction is sustained through recycling a portion of product syngas into a fuel cell and using a portion of electric power generated to heat the reformer for continuous operation. Such reforming reactor may be miniaturized into a size of PC, then you have a Personal Reformer(PR).