• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.704-710
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• 2014

Biomass is considered an alternative energy which can solve an greenhouse gas problem like $CO_2$ which is a major contributor to global warming. The biomass can be converted to various energy sources through thermochemical conversion. In this study, a continuous gasifier was engineered for a wood biomass gasification. The biomass was used a waste wood. The experiments of $CO_2$ gasification were achieved as the gasification temperature, moisture content and input $CO_2$ concentration. The results showed that the yield of producer gas increased with an increasing the gasification temperature. The amount of the light tar increased due to the decomposition of gravimetric tar by the thermal cracking, and the char was confirmed pore development through the SEM analysis. The CO concentration was increased with an increased input $CO_2$ concentration from Boudouard reaction. Through the parametric screening studies, the hydrogen and carbon monoxide concentration were 32.91% and 48.33% at the optimal conditions of this test rig.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.908-912
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• 2012

Lauan sawdust was gasified by steam reforming for hydrogen production from biomass waste. The fixed bed gasification reactor with 1m height and 10.2 cm diameter was utilized for the analysis of temperature and catalysts effect. Steam was injected to the gasification reactor for the steam reforming effect. Lauan sawdust was mixed with potassium carbonate, sodium carbonate, calcium carbonate, sodium carbonate + potassium carbonate and magnesium carbonate + calcium carbonate catalysts of constant mass fraction of 8:2 which was injected to the fixed gasification equipment. The compositions of production gas of gasification reaction were analyzed at the temperature range from $400^{\circ}C$ to $700^{\circ}C$. Fractions of hydrogen, methane and carbon monoxide gas in the production gas increased when catalysts were used. Fractions of hydrogen, methane and carbon monoxide gas were increased with increasing temperature. The highest hydrogen yield was obtained with sodium carbonate catalyst.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.114-119
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• 2011

Thermogravimetric analysis(TGA) was carried out for pyrolysis and char-$CO_2$ gasification of low rank Indonesian ABK coal and China lignite. The pyrolysis rate was successfully described by a two-step model adopting the modified Kissinger method. The shrinking core model, when applied to char-$CO_2$ gasification gave initial activation energy of 189.1 kJ/mol and 260.5 kJ/mol for the ABK coal and China lignite, respectively. Thus, the char-$CO_2$ gasification has been successfully simulated by the shrinking core model. In particular, the activation energy of char-$CO_2$ gasification calculated in this work is similar to the results on the anthracite coal, but considerable difference exists when other models or coal types are used.

• Clean Technology
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• v.21 no.1
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• pp.53-61
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• 2015

In this study, we have investigated the kinetics on the char-CO₂ catalytic gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-CO₂ catalytic gasification of an Indonesian Kideco sub-bituminous. Na₂CO₃ and K₂CO₃ were selected as catalysts which were physically mixed with coal. The char-CO₂ catalytic gasification reaction showed a rapid increase of carbon conversion rate at 850 ℃, 60 vol% CO₂, and 7 wt% Na₂CO₃. At the isothermal conditions ranging from 750 ℃ to 900 ℃, the carbon conversion rates increased as the temperature increased. Four kinetic models for gas-solid reaction including the shrinking core model (SCM), random pore model (RPM), volumetric reaction model (VRM), and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM for the Kideco sub-bituminous. The activation energies for each char mixed with Na₂CO₃ and K₂CO₃ were found 55-71 kJ/mol and 69-87 kJ/mol.

• Journal of Hydrogen and New Energy
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• v.26 no.1
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• pp.8-14
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• 2015

In this study, the model biomass was used for hydrogen production by supercritical water gasification (SCWG). Model biomasses were glycerol, glycine, lignin and cellulose. The feed concentration was set to 1 wt%. Experiments were conducted in a reactor at $440^{\circ}C$ and above 26.3 MPa for 30 min. The effects of catalysts such as alkali metal salt ($K_2CO_3$ and $Na_2CO_3$) and transition metal salts ($Ni(NO_3)_2$, $Fe(NO_3)_3$ and $Mn(NO_3)_2$) on the gasification were systematically investigated. No tar or coke was observed in all experiments. The results showed that the gasification efficiency increased with various catalysts. For the cellulose and glycerol, all catalysts were effective for the promoted $H_2$ production compared with no catalyst. The significant decrease of $H_2$ production compared with no catalyst was observed with $Na_2CO_3$ and $Fe(NO_3)_3$ for glycine and lignin. respectively. The highest H2 production, 1.24 mmol was obtained for glycerol-SCWG with $Mn(NO_3)_2$. Conclusively, the addition of $Mn(NO_3)_2$ enhanced all model biomass gasification efficiency and increased the hydrogen production promoting the supercritical water reaction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1690-1700
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• 1997

Entrained coal gasification tests with Datong coal were performed to assess the influence of oxygen/coal ration and pressure. When gasification condition in oxygen/coal ratio has changed from 0.5 to 1.0, optimal gasification condition from low pressure runs was oxygen/coal ratio of approximately 0.9 where CO was produced about 40% and H, about 20%. Under the pressure condition of 12-14 atmospheres, optimal oxygen/coal ratio value was in the region of 0.6 where CO was produced about 55% and H2about 25%. From these results, it was found that the oxygen/ coal ratio for the maximum production of CO and H, was decreasing with the increase in gasifier pressure and also, with increasing oxygen content, carbon conversion was increased. For the Chinese Datong coal, cold gas efficiency was in the range of 40-80%.

• Journal of Hydrogen and New Energy
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• v.27 no.6
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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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.1000-1006
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• 2009

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, $CO_2,\;H_2O,\;CH_4$) for three different coals. The influence of coal structure on gas evolution is examined over the pressure range of 10${\sim}$30atm.

• Journal of Energy Engineering
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• v.16 no.1 s.49
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• pp.32-39
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• 2007

Coal pyrolysis processes vary with the origin and rank of coal. It is difficult to generalize the characteristics of coal pyrolysis reaction because the process consists of numerous reactions including pyrolysis, gasification, and combustion. To find out the optimum process condition it is necessary to determine the condition fur each coal from the smatter scale experiment. In this study pressurized ($2kg_{f}/cm^{2}$) fluidized bed, low temperature ($735{\sim}831^{\circ}C$) gasification using Kideco coal was performed. The reaction condition and product gas composition were determined from the variables including steam flow rate, coal feed rate and air flow rate. Optimum reaction condition was determined from the concentrations of $H_{2}$, and CO in the product gas. The ratio of air/coal was 4.45 and that of steam/coal was 0.21 respectively. The concentrations of CO and $H_{2}$ decreased with the increase of $CO_{2}$. It is important to control the feed rates of coal and steam because the reaction temperature rapidly increased when the combustion reaction dominates over the gasification reaction. The concentrations of CO and $H_{2}$ were 18%, 17% respectively from the continuous operating condition.

• Journal of Hydrogen and New Energy
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• v.23 no.3
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• pp.274-284
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• 2012

Recently, gasification technology for coal blended with biomass has been an issue. Especially, An advantages of coal blended with biomass are 1) obtaining high cold gas efficiency, 2) obtaining syn-gas of high-high heating value (HHV), and 3) controlling occurrence of $CO_2$. In this study, the efficiency and characteristic of 300 MW Shell type gasifier were predicted using CFD simulation. The CFD simulation was performed for biomass coal blending ratios of 0~0.2, 0.5, 1 and $O_2$/fuel ratios of 0.5~0.84. Kinetic parameters (A, $E_a$) obtained by $CO_2$ gasification experiment were used as inputs for the simulation. In results of CFD simulation, residence times of particle in 300MW Shell type gasifer presented as 7.39 sec ~ 13.65 sec. Temperature of exit increased with $O_2$/fuel ratio as 1400 K ~ 2800 K, while there is not an effects of biomass coal blending ratios. Considering both aspects of temperature for causing wall slagging and high cold gas efficiency, the optimal $O_2$/fuel ratio and blending ratio were found to be 0.585 and 0.05, respectively.