Chung Hwan Jeon

Experimental Study on Particle Temperature and CO/CO2Emission Characteristics of Pulverized Coal Combustion Condition According to Coal Types in Blast Furnace

This study was performed using a laminar flow reactor that could replicate the combustion environment of pulverized coal in a blast furnace. Since a pulverized coal injection system was developed for iron making, the combustion characteristics of pulverized coal have been important in the iron and steel industry. The flame structure, particle temperature, and exhaust gas were investigated for different types of coal. The results of this study demonstrated that the combustion characteristics of coal are influenced by several properties of individual coals. In particular, the CO emission and volatile matter content of individual coals were found to have a strong influence on their combustion characteristics. Thus, this study found the properties of the coals to be significant and focused on the particle temperature and CO and CO2 emissions.

Investigation of Tar/soot Yield of Bituminous and Low Rank Coal Blends

Soot and tar which were derived from combustion or pyrolysis processes in Puverized Coal(PC) furnace or boiler have been significantly dealing in a radiative heat transfer and an additional source of NOx. Furthermore, the increasing for the use of a coal with low caloric value gives rise to a lot of tar-soot yield and LOI in a recycled ash for using cement materials. So, the ash with higher tar-soot yield and LOI can not recycle due to decreased strength of concrete. In this study, tar-soot yields and flame structures were investigated using the LFR for a blending combustion with bituminous coal and sub-bituminous coal. Also, The investigation were conducted as each single coals and blending ratio. The coals are used in a doestic power plant. In the 에너지공학 제 권 제 호 , 23 2 (2014) Journal of Energy Engineering, Vol. 23, No. 2, pp. 42~48(2014) http://dx.doi.org/10.5855/ENERGY.2014.23.2.042 To whom corresponding should be addressed. School of Mechanical Engineering, Pusan National Univ., Jangjeon 2-dong, Geumjeong-gu, Busan, 609-735 Korea Tel : 051-510-3035 E-mail : chjeon@pusan.ac.kr 발전용 역청탄과 저열량탄 혼소시 의 배출 특성 연구 Tar/Soot Journal of Energy Engineering, Vol. 23, No. 2 (2014) 43 experimental results, sub-bituminous coal with high volatile contents shows longer soot cloud length than bituminous coal, but overall flame length was shorter than bituminous coal. Tar-soot yields of sub-bituminous coal is lower than those of bituminous coal. Combustion characteristics are different between single coal and blended coal. Therefore, finding an optimal coal blending ratio according to coal rank effects on tar-soot yields.

LFR에서 탄종에 따른 휘발분과 산소농도가 타르와 수트의 발생률에 미치는 영향

− This study was performed by using an LFR (laminar flow reactor), which can be used to carry out different types of research on coal. In this study, an LFR was used to analyze coal flames, tar and soot yields, and structures of chars for two coals depending on their volatile content. The results show that the volatile content and oxygen concentration have a significant effect on the length and width of the soot cloud and that the length and width of the cloud under combustion conditions are less than those under a pyrolysis atmosphere. At sampling heights until 50 mm, the tar and soot yields of Berau (sub-bituminous) coal, which contains a large amount of volatile matter, are less than those of Glencore A.P. (bituminous) coal because tar is oxidized by the intrinsic oxygen component of coal and by radicals such as OH-. On the other hand, at sampling heights above 50 mm, the tar and soot yields of Berau coal are higher than those of Glencore A.P. coal by reacted residual volatile matter, tar and light gas in char and flame. With above results, it is confirmed that the volatile matter content and the intrinsic oxygen component in a coal are significant parameters for length To whom correspondence should be addressed. E-mail: chjeon@pusan.ac.kr LFR에서 탄종에 따른 휘발분과 산소농도가 타르와 수트의 발생률에 미치는 영향 1035 Korean Chem. Eng. Res., Vol. 50, No. 6, December, 2012 and width of the soot cloud and yields of the soot. In addition, the B.E.T. results and the images of samples (SEM) obtained from the particle separation system of the sampling probe support the above results pertaining to the yields; the results also confirm the pore development on the char surface caused by devolatilization.

Coal Ash Combustion Simulation for 500-MW Coal-firing Boiler

KeyWords: Ash(회), Boiler(보일러), CFD(전산유체역학), LOI(점화감소량), TGA(열중량분석), DTF(수직형전기로)초록: 석탄은고정탄소분, 휘발분, 수분, 회로구성되며, 연소시회성분과소량의고정탄소분이남게된다. 석탄화력발전소에서는석탄연소후나오는잔여물(고정탄소분, 회)를통칭하여석탄회라고부르고있다. 현재발전소에서는정제회(LOI함량6%미만)는경량골재의원료로재활용해수익을창출하고있으나, LOI함량이높은회는재활용이불가능해땅에매립하고있다. 이에따라환경적인부담금을줄이고정제회판매의수익을올리기위해회성분의LIO감량은필수적이다. 본연구에서는TGA(Thermo-gravime- tric analysis)와DTF(Drop tube furnce)실험을통해석탄과석탄회연소를위한실험적인상수값을결정하였다. 500MW급표준화력발전보일러를모델링하고, 전산해석을위해격자를형성시키고적절한해석모델을선정하였으며, 석탄회재연소시뮬레이션을수행하여석탄회투입시보일러내부의온도및유동을모사하였다. 보일러내부석탄입자와회입자의이동궤적을통해가능한높은버너위치에서석탄회를투입하는것이적절함을나타내었다. 또한실제설치가능한D버너에서6ton/h로공급시에기존의보일러에큰영향을주지않으며재연소가능함을알수있다.Abstract: In thermal power generation companies, the recycling of refined ash (LOI 6%) in a PC-firing furnace can be an alternative. In this study, a numerical analysis was performed todemonstrate the effects of ash re-burning. An experimental constant value was decided by TGA (thermo-gravimetricanalysis), and a DTF (drop-tube furnace) was used in the experiment for calculating the combustion of ash. On thebasis of the trajectory of the moving particles of coal and ash, it was concluded that supplying ash near the burner,which is located high above the ground, is appropriate. On the basis of numerical results, it was concluded that an ashsupply rate of 6 ton/h is suitable for combustion, without affecting the PC-firing boiler.

Experimental Study of Char Oxidation and Kinetic Rate in O2/CO2and O2/N2Environments

We investigated the combustion rate and kinetic rate of char when burning in oxygen-enriched atmospheres with either an or bath gas in a drop tube furnace. The experiments were performed with sub-bituminous coal (Adaro) and bituminous coal (Coal valley) under atmospheric pressure conditions. Two different coals were investigated over 12 to 30 vol% oxygen and furnace temperatures of 900, 1100, and . For both coals, the particle temperature and overall reaction rate are lower in the bath gas. However, analysis of single-particle data shows that the surface-specific burning rate of char oxidation is similar in both gases. In addition, the kinetic rate and activation energy for each coal were similar for both gases. Generally, the particle temperature and overall reaction rate of sub-bituminous coal are higher than those of bituminous coal.

A Theoretical Analysis on Volatile Matter Release from Different Coals Using CPD Model During a Coal Gasification

Integrated Coal Gasification Combined Cycle (IGCC) power plants have been developed to reduce carbon dioxide emissions and to increase the efficiency of electricity generation. A devolatilization process of entrained coal gasification is predicted by CPD model which could describe the devolatilization behavior of rapidly heated coal based on the chemical structure of the coal. This paper is intended to compare the mass release behavior of char, tar and gas(CO, ) for three different coals. The influence of coal structure on gas evolution is examined over the pressure range of 1030atm.

Effects of a swirling and recirculating flow on the combustion characteristics in non-premixed flat flames

The effects of swirl intensity on non-reacting and reacting flow characteristics in a flat flame burner (FFB) with four types of swirlers were investigated. Experiments using the PIV method were conducted for several flow conditions with four swirl numbers of 0, 0.26, 0.6 and 1.24 in non-reacting flow. The results show that the strong swirling flow causes a recirculation, which has the toroidal structures, and spreads above the burner exit plane. Reacting flow characteristics such as temperature and the NO concentrations were also investigated in comparison with non-reacting flow characteristics. The mean flame temperature was measured as the function of radial distance, and the results show that the strong swirl intensity causes the mean temperature distributions to be uniform. However the mean temperature distributions at the swirl number of 0 show the typical distribution of long flames. NO concentration measurements show that the central toroidal recirculation zone caused by the strong swirl intensity results in much greater reduction in NO emissions, compared to the non-swirl condition. For classification into the flame structure interiorly, the turbulence Reynolds number and the Damkohler number have been examined at each condition. The interrelation between reacting and non-reacting flows shows that flame structures with swirl intensity belong to a wrinkled laminar-flame regime.

The Co-Combustion Characteristics of Coal and Wood Pellet in a 25W Lab-scale Circulating Fluidized Bed Reactor

Circulating Fluidized Bed(CFB) combustion has the several advantages which are the fuel flexibility, the economy, the efficiency and the environment. It is necessary to apply a renewable energy to produce electricity due to the Renewable Portfolio Standard(RPS) mandates recently. So, in this study, co-combustion with a coal and a wood pellet was investigated to evaluate the combustibility and the environment as function of blending ratio of them in a Lab-scale CFB reactor. To investigate the characteristics of the co-combustion, the blending ratio which is the weight of wood pellet by the total calorific value of the supplied, was considered. Bed material was a river sand(No. 7). As increasing the blending ratio, the exhausted gas emissions such as CO, NOx, HC and SOx were decreased. But in case of wood pellet over 30%, CO, HC and SOx emission were increased. And the gas temperatures at the downstream were decreased.

The Study on the Combustion and Ash Deposition Characteristics of Ash Free Coal and Residue Coal in a Drop Tube Furnace

Recently, much research has been put into finding the causes and solutions of slagging/fouling problems that occur at the end of the boiler. This slagging/fouling, caused by low-rank coal`s ash, disturbs the thermal power and greatly reduces efficiency. In environmental aspects, such as NOx pollution, governments have been implementing restrictions on the quantity of emission gases that can be released into the atmosphere. To solve these problems, research on Ash Free Coal (AFC), which eliminates ash from low-rank coal, is in progress. AFC has advantages over similar high-rank coals because it increases the heating value of the low grade coal, reduces the contaminants that are emitted, and decreases slagging/fouling problems. In this study, using a DTF, the changes of NOx emissions, unburned carbon, and the characteristics of ash deposition were identified. KCH raw coal, AFC extracted from KCH, residue coal, Glencore, and Mixed Coal (Glencore 85wt% and residue coal 15wt%) were studied. Results showed that AFC had a significantly lower emission of NOx compared to that of the raw coal and residue coal. Also, the residue coal showed a higher reactivity compared to raw coal. And finally, In the case of the residue coal and mixed coal, they showed a lower ash deposition than that of low-rank coal.

Effect of Pressure and Stoichiometric Air Ratio on NOx Emissions in Gas-Turbine Dump Combustor with Double Cone Burner

This work presents an experimental investigation of NOx emissions according to inlet air temperature (550-660 K), stoichiometric air ratio (, 1.4-2.1), and elevated pressure (2-5 bar) in a High Press Combustor (HPC) equipped with a double cone burner, which was designed by Pusan Clean Coal Center (PC3). The exhaust-gas temperature and NOx emissions were measured at the end of the combustion chamber. The NOx emissions generally decreased as a function of increasing . On the other hand, NOx emissions were influenced by , inlet air temperature and pressure of the combustion chamber. In particular, when the inlet air temperature increased, the flammability limit was extended to leaner conditions. As a result, a higher adiabatic temperature and lower NOx emissions could be achieved under these operation conditions. The NOx emissions that were governed by thermal NOx were greatly increased under elevated pressures, and slightly increased at sufficiently low fuel concentrations ( >1.8).