• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.442-451
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• 2010

This paper describes the calculation method to obtain the product composition of coal pyrolysis at high pressure and high temperature. The products of coal pyrolysis should be determined for the coal gasifier simulation, and this is the first step of the coal gasifier simulation. The pyrolysis product distribution greatly affects the coal gasifier efficiency such as carbon conversion, cold gas efficiency and the syngas composition at the outlet of the gasifier. The present calculation method is based on the coal ultimate/proximate analysis and several correlations among gasifier pressure, coal properties and pyrolysis products. The calculated products for 5 coals have been compared with those from the commercial pyrolysis model.

• Advances in Energy Research
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• v.8 no.4
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• pp.265-273
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• 2022

In this study, a product gas yield and carbon conversion were measured during the coal pyrolysis. The pyrolysis process occurred under two different atmospheres such as subcritical (45 bar, 10℃) and supercritical CO₂ condition (80 bar, 35℃). Under the same pressure (80 bar), the atmosphere temperature increased from 35℃ to 45℃ to further examine temperature effect on the pyrolysis at supercritical CO₂ condition. For all three cases, a power input supplied to heating wire placed below coal bed was controlled to make coal bed temperature constant. The phase change of CO₂ atmosphere and subsequent pyrolysis behaviors of coal bed were observed using high-resolution camcorder. The pressure and temperature in the reactor were controlled by a CO₂ pump and heater. Then, the coal bed was heated by wire heater to proceed the pyrolysis under supercritical CO₂ condition.

• Environmental Engineering Research
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• v.23 no.2
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• pp.121-128
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• 2018

This paper describes the non-isothermal pyrolysis of cashew shell cake (CSC) - bituminous coal blends. The blends exhibit two distinct stages in the thermogravimetric curves, which the first stage stems from CSC and the second one from the superposition of CSC and coal pyrolysis. The pyrolysis behavior of the blend was linearly proportional to the blending ratios. The overall behavior of the blends was evaluated in terms of the maximum rate of weight loss, characteristic temperatures, char yields, and the calculated and experimental thermogravimetric curves. The activation energies ranged up to 49 kJ/mol for the blends were obtained and used to evaluate the interaction in the blends. The present thermogravimetric study shows that there is no significant interaction between CSC and coal in the blends, and it was supported by the characteristic values which are linearly proportional to the weight percentages of cashew cake-shell in the blends. The no-interaction might be due to the fact that the main reaction zones are distinctively different for two constituents, so the additive rule is acceptable for describing pyrolysis behavior of the present blends.

• Environmental Engineering Research
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• v.22 no.3
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• pp.320-328
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• 2017

This paper describes the non-isothermal pyrolysis of wood pellet and saw dust, and their blends with bituminous coal. The blends showed the distinct, two peaks in thermogravimetric curves, and the first peak came from the biomass pyrolysis and the second one came from the coal pyrolysis. The interaction in the blend was evaluated in terms of the maximum rate of weight loss, characteristic temperatures, char yields, and the calculated and experimental thermogravimetric curves. The activation energies and frequency factors for the blends were obtained with the multi-stage, Coats and Redfern method. The respective activation energies of 73 and 67 kJ/mol and the frequency factors of 725,100 and $65,262min^{-1}$ were obtained for the present wood pellet and saw dust samples. The thermogravimetric study shows that there is no significant interaction between the present biomass and coal in the blends, and the pyrolysis behavior can be described with the additive rule.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.208-214
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• 1993

Pyrolysis of bituminous coal has been carried out in a two-stage fixed bed reactor to produce high heating value gas(7000 kcal/N㎥) for industrial or town gas usage. The effects of coke catalyst, pyrolysis temperature (468∼565$^{\circ}C$), and catalytic cracking temperature (700∼850$^{\circ}C$) on the product gas properties from pyrolysis of bituminous coal have been determined. From pyrolysis of Dong Jin coal with coke, the carbon deposition on catalyst is found to be less than 5% of product tar and approximately 15% of total energy iii the parent coal can be recovered as high heating value gas. Oil composition in the product tar from the two-stage pyrolysis is higher than that from low-temperature pyrolysis. The tar produced from pyrolysis below 516$^{\circ}C$ can be easily catalytically cracked but, the tar produced above 565$^{\circ}C$ cannot be cracked easily with catalyst. From the product gas analysis, the catalytic cracking temperature should be maintained below 800$^{\circ}C$ since cracking speed of ethylene increases remarkably with the cracking temperature above 800$^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.3
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• pp.260-268
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• 2019

The pyrolysis characteristics of pulverized coal particle was numerically analyzed with the drop tube furnace. Based on the simulated gas flow field in the drop tube furnace, the particle velocity, temperature and volatile evolution were calculated with the fourth order Runge-Kutta method. The effects of changes in reactor wall temperature and particle diameter on the pyrolysis behavior of coal particle were investigated. The particle heating rate was very sensitive to the reactor wall temperature and particle size, that is, the higher wall temperature and the smaller particle size resulted in the higher heating rate and the consequent quicker volatile evolution.

• Clean Technology
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• v.8 no.1
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• pp.1-9
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• 2002

Mild pyrolysis of four different coals (two bituminous coals and two Korean antracite) was investigated. Desulfurization characteristics, weight loss and variation of heating values were studied. As operating variables of experiment, pyrolysis temperature($350{\sim}550^{\circ}C$), pyrolysis time(5~20 min.) and particle size(0~3.55mm) were examined. The maximum sulfur removal rate of bituminous coal and anthracite were 38% and 28%, respectively. The optimum mild pyrolysis conditions were 10~15 min for pyrolysis time and $450{\sim}550^{\circ}C$ for pyrolysis temperature. The mild pyrolysis was effective to reduce organic sulfur content. Heating values of char per mass after pyrolysis increased about 5% compared to raw coal. The effect of coal particle size on the desulfurization was not observed.

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.717-725
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• 1989

An experimental investigation on the combustion behavior of pulverized coal particles was performed using the cross-section micrography techniques while sample coal particles were collected in-situ from the flow reactor. The coal particles were representative of pulverized bituminous coal undergoing a raped pyrolysis and combustion, however, quenched at the time when the particles were deposited onto a sample plate. The internal structure of coal was observed to change as deposited. Upon injection into a flow reactor, bituminous coal particles showed many holes which represented internal pore formation during the pyrolysis. The relative portion of the remaining matrix of coal was decreasing as the residence time progressed. This direct observation of cross-section of burning particles enabled better understanding of the coal combustion behavior.

• Journal of Energy Engineering
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• v.18 no.1
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• pp.9-16
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• 2009

The experimental work has been carried out for the study of pyrolysis and char-air reaction of five coals used in Y power station in Korea. For five coals, the characteristics of pyrolyis and char reaction have been investigated with TGA, and their kinetic parameters were obtained and compared each other. The order of pyrolysis rate for five coals were as follows : Peabody, Flame, MIP, Indominco, Elk valley. The behavior of char - air reaction for five coal chars have been successfully described by the grain model. The rate of char-air reaction gave the maximum value for Flame coal char, on the while Elk valley coal char had the minimum value. For the reaction temperature over 1,000K, Flame coal char - air reaction was very fast compared with other coal chars.