• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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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.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.1-8
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• 2022

Hydrogen can be produced by gasification of biomass and other combustible fuels. Depending on oxydant agents, syngas or producer gas compositions become quite different. Since biomass has limited amount of hydrogen including moisture in it, the hydrogen concentration in the syngas is about 15% when air is supplied for oxidant agent. Experiments were conducted to investigate the channges in hydrogen concentrations in syngas with different oxidant agent conditions, fuel conditions, and external heat supply. Allothermal reaction resulted in higher concentrations of hydrogen with the supply of steam over air, reaching over 60%. Hydrogen is produced by water-gas and water-gas shift reactions. These reactions are endothermic and require enough heat. Autothermal reaction occurred in the downdraft gasifier used in the experiment did not provide enough heat in the reactions for hydrogen production. Steam seems a more desirable oxidant agent in producing the syngas with higher concentrations of hydrogen from biomass gasifications since nitrogen is included in syngas when air is used.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.267-270
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• 2014

Since contaminants of syngas obtained from the biomass gasification are removed, the syngas is clean fuel. In this study a high-efficiency energy production system is developed. The system produces electricity using a waste pressure and feeds a low-pressure steam to Dyeing industrial complex. Also, iron oxide derived from dyeing sludge is utilized as a self-catalyst to reform a tar and reduce a tar emission from gasifier. This system increases the amount of syngas and finally achieves a highly efficient gasification.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.460-469
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• 2010

To develop coal gasfication system, many studies have been actively conducted to describe the simulation of steady state. Now, it is necessary to study the gasification system not only in steady state but also in dynamic state to elucidate abnormal condition such as start-up, shut-down, disturbance, and develop control logic. In this study, a model was proposed with process simulation in dynamic state being conducted using a chemical process simulation tool, where a heat and mass transfer model in the gasifier is incorporated, The proposed model was verified by comparison of the results of the simulation with those available from NETL (National Energy Technology Laboratory) report under steady state condition. The simulation results were that the coal gas efficiency was 80.7%, gas thermal efficiency was 95.4%, which indicated the error was under 1 %. Also, the compositions of syngas were similar to those of the NETL report. Controlled variables of the proposed model was verified by increasing oxygen flow rate to gasifier in order to validate the dynamic state of the system. As a result, trends of major process variables were resonable when oxygen flow rate increased by 5% from the steady state value. Coal flow rate to gasifier and quench gas flow rate were increased, and flow rate of liquid slag was also increased. The proposed model in this study is able to be used for the prediction of gasification of various coals and dynamic analysis of coal gasification.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.285-292
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• 2012

The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with that of other coal fueled power generation system. IGCC offers substantial advantages over pulverized coal combustion when carbon capture and storage (CCS) is required. Commercial plants employ different types of quenching system to meet the purpose of the system. Depending on that, the downstream units of IGCC can be modeled using different operating conditions and units. In case with $CO_2$ separation and capture, the gasifier product must be converted to hydrogen-rich syngas using Water Gas Shift (WGS) reaction. In most WGS processes, the water gas shift reactor is the biggest and heaviest component because the reaction is relatively slow compared to the other reactions and is inhibited at higher temperatures by thermodynamics. In this study, tehchno-econimic assessments were found according to the quench types and operating conditions in the WGS system. These results can improve the efficiency and reduce the cost of coal gasification.

• Journal of Energy Engineering
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• v.10 no.3
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• pp.206-213
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• 2001

Gasification kinetics of an Indonesian sub-bituminous coal-char with $CO_2$at elevated pressure was investigated with a pressurised drop tube furnace reactor. The effects of reaction temperature (900~140$0^{\circ}C$), partial pressure of carbon dioxide (0.1~0.5 MPa), and total system pressure (0.5, 0.7, 1.0, 1.5MPa) on gasification rate of the coal char with $CO_2$have been determined. It was found that the gasification rate was dependent on the total system pressure with the same partial pressure and temperature. The $n^{th}$ order rate equation (R=k $P^{g}$ $_{asn}$) was modified to be R=k $P^{g}$ $_{asn}$ $P^{m}$ $_{total}$ to describe the gasification rate where the total system pressure was changed. The gasification reaction rate of char-$CO_2$at high temperature and elevated pressure may be expressed as dX/dt=(174.1)exp(-71.5/RT)( $P_{CO2}$)0.40( $P_{total}$ )0.65(1-X)$^{2}$ 3/.X> 3/.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.804-807
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• 2007

The acid gas removal (AGR) system was designed and installed to remove $H_2S$ in coal syngas in the pilot-scale coal gasification system for producing chemicals like Dimethyl Ether(DME). The syngas from the coal gasification at the rate of $100{\sim120$ $Nm^3$/hr included pollutants such as fly ash. $H_2S$, COS, $NH_3$, etc. The designed temperature and pressure of the AGR system are below 50oC and 8 kg/$cm^2$. Fe-chelate was used as an absorbent. $H_2S$ was stably removed below 0.5 ppm in the AGR system when the concentration of $H_2S$ was $150{\sim}450$ ppm. The pH of Fe-chelate solution was also stably maintained between $8{\sim}9$. FeMgO absorbent was also tested to remove $H_2S$ in the lab-scale AGR system and $H_2S$ was also removed below 0.5 ppm in the initial operation.

• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.58-65
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• 2017

Fluidized bed gasification is technically and economically proven technology, which shows the high possibility of realization and commercialization. However, in Korea, development of FBG to the commercial scale for power generation and industry is mainly blocked by the fact that there is no experience of design, troubleshooting and operation of even pilot scale fluidized bed gasifier. In this study, a $3MW_{th}$ circulating fluidized bed(CFB) was newly developed for biomass gasification. The fluidized bed was mainly composed of circulating and bubbling fluidized reactors integrating in-situ tar removal step in the system. For cleaning of the tar and acid gas in the product gas, the sequential gas cleaning process comprised of a ceramic filter, rapid quencher and wet scrubber was adopted. Effect of equivalence ratio was investigated to find the optimal operating conditions for the $3MW_{th}$ integrated system of fluidized bed gasification.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.1-6
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• 2006

This paper presents the applicability of low caloric synthetic gas from coal gasification to a gas engine system and small sized generator. A commercial LPG engine is modified to use the low caloric synthetic gas from coal gasification as the gas engine fuel. The modification is focused on the fuel supplying system, which includes air flowrate adjusting orifice, gas mixer, vaporizer, preheater, regulators, and fuel tank. From the results of engine performance data, we have demonstrated that the engine modified by using the coal gasification gas is well operated from idle to wide open throttle conditions although the engine power is somewhat reduced relative to LPG fueled engine. And we have also demonstrated that the generator is well operated with various loads.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.533-540
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• 2014

Recently, latent heat thermal energy storage system (LHTES) has gained attention in order to utilize middle temperature (373~573 K) waste heat from biomass gasification. This paper has investigated thermo-physical properties of erythritol [$CH_2OHCHOH$ $CHOHCH_2OH$], mannitol [$CH_2OH$ $(CHOH)_4CH_2OH$] and their compounds as phase change materials (PCMs). The differential scanning calorimetry (DSC) was applied to measure the melting point and latent heat of these PCMs. Also the melting and solidification characteristics of these PCMs were observed in a glass tube with a digital camera. In the DSC measurement, when the amount of mannitol content was more than 40 mass%, the melting point of these compounds show two melting points. The experimental results showed that the velocity of melting and solidification were different for every mixture ratio of compounds. These compounds had the super-cooling phenomenon during the solidification process.