• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.604-610
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• 2007

Characteristics of steam gasification and combustion of naphtha tar pitch, which is the bottom product of naphtha cracking process, were investigated by using the thermo gravimetric analyzer to develop the technology for obtaining syngas by using the naphtha tar pitch as a carbon source. Friedman's and Ozawa-Flynn-Wall method were used to calculate activation energy, reaction order and frequency factor of reaction rate constant for both of steam gasification and combustion. The activation energy of combustion of naphtha tar pitch based on the fractional conversion by Friedman's method was in the range of 41.58 ~ 68.14 kJ/g-mol when the fractional conversion level was in the range of 0.2~0.6, but 183.07~191.17 kJ/g-mol when the conversion level was 0.9~1.0, respectively. In case of steam gasification of naphtha tar pitch, the activation energy was in the range of 31.87~44.87 kJ/g-mol in the relatively lower conversion level (0.2~0.6), but 70.63~87.79 kJ/g-mol in the relatively higher conversion level (0.8~0.95), respectively. Those results exhibited that the steam gasification as well as combustion would occur by means of two steps such as devolitilization followed by combustion or gasification.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.97-99
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• 2012

A pressure-based BOIK model considering Shock to Detonation Transition(SDT) and damage due to external fragment or bullet stimuli impact on energetic materials and analytical approach for determination of free parameters are proposed. The rate of product mass fraction(${\lambda}$) consists of ignition term that represents the initiation due to shock compression and growth term that describes propagation of detonation wave and strain term representing the morphological deformation induced by external impact.

• 연구논문집
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• s.29
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• pp.5-15
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• 1999

Present study deals with performance analysis of an inert gas generator (IGG) which is to be used as an effective mean to suppress the fire. The IGG uses a turbo jet cycle gas turbine engine to generate inert gas for fire extinguishing. It is generally known that a lesser degree of oxygen content in the product of combustion will increase the effectiveness of fire suppressing. An inert gas generator system with water injection will bring advantages of suffocating and cooling effects which are considered as vital factors for fire extinguishing. As the inert gas is injected to the burning site, it lowers the oxygen content of the air surrounding the flame as well as reduces the temperature around the fire as the vapour in the inert gas evaporates during the time of spreading. Some important aspects of influencing parameters, such as, air excess coefficient. $\alpha$, compressor pressure ratio, $ pi_c$, air temperature before combustion chamber, $T_2$, gas temperature after combustion chamber, $T_3$, mass flow rate of water injection, $M_w$, etc., on the performance of IGG system are investigated. Calculations of total amount of water needed to reduce the turbine exit temperature to pre-set nozzle exit temperature employing a heat exchanger were made to compare the economics of the system. A heat exchanger with two step cooling by water and steam is considered to be better than water cooling only. Computer programs were developed to perform the cycle analysis of the IGG system and heat exchanger considered in the present study.

• Environmental Engineering Research
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• v.10 no.3
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• pp.131-137
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• 2005

The catalytic activity of precious metals(Rh, Pd, Pt) and nickel catalysts supported on ${\gamma}-Al_2O_3\;and\;CeO_2$ in the partial combustion of methane(PCM) to syngas was investigated based on the product distribution in a fixed bed now reactor under atmospheric condition and also on analysis results by SEM, XPS, TPD, BET, and XRD. The activity of the catalysts based on the syngas yield increased in the sequence $Rh(5)/CeO_2{\geq}Ni(5)/CeO_2>>Rh(5)/Al_2O_3>Pd(5)/Al_2O_3>Ni(5)/Al_2O_3$. Compared to the precious catalysts, the syngas yield and stability of the $Ni(5)/CeO_2$ catalyst were almost similar to $(5)/CeO_2$ catalyst, and superior to these of any other catalysts. The syngas yield of $Ni(5)/CeO_2$ catalyst was 90.66% at 1023 K. It could be suggested to be the redox cycle of the successive reaction and formation of active site, $Ni^{2-}$ and the lattice oxygen, $O^{2-}$ produced due to reduction of $Ce^{4-}$ to $Ce^{3-}$.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.7-8
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• 2006

As a new type of flame, tubular flame has attracted much attention from a fundamental viewpoint and many experimental and theoretical studies have been made on its characteristics. Recently, it is also recognized that the tubular flame has great potentials as practical combustor because its stability range is very wide in fuel concentration and also in injection velocity. Thus, tubular flame burners have been developed for various kinds of fuels. They are gaseous fuels of methane, propane, hydrogen, and by-product fuels gases in steel making processes including BFG (Blast Furnace Gas), LDG (LD Converter Gas), and COG (Cokes-Oven Gas), liquid fuels of kerosene, A-type and C-type heavy oils, and a solid fuel of biomass powder. In this paper, recent developments of the tubular flame burners have been briefly introduced.

• Journal of the Korean Society of Combustion
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• v.19 no.4
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• pp.49-55
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• 2014

Design criterion for the size of micro Pt-catalytic combustor is investigated in terms of heat release rate. One-dimensional plug flow model is applied to determine the surface reaction constants using the experimental data at stoichiometric butane-air mixture. With these reaction constants, the mass fraction of butane and heat release rate predicted by the plug flow model are in good agreement with the experimental data at the combustor exit. The relationship between the size of micro catalytic combustor and mixture flowrate is introduced in the form of product of two terms-the effect of fuel conversion efficiency, and the effect of chemical reaction rate and mass transfer rate.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.341-348
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• 1995

An analysis of the use of temperature profiles in the determination of the kinetic parameters of combustion synthesis of Ti5Si3 were investigated. From profile analysis, an apparent activation energy of 12KJ/mol was calculated. The Maximum heating rate achieved during 10wt% Ti5Si3 reaction by the product dilution method was approximately $1.5\times$104 K/s. Coupling this value with the measured wave velocity of 7.02 cm/s yields a maximum thermal gradient of 2.14$\times$103 K/cm. The value of tr (=t*) was calculated to be 1.2$\times$10-1 s and the value of td (=tx) was calculated to be 32.89 s. Using the definition of t* and the measured wave velocity, the effective thermal diffusivity, $\alpha$, was calculated to be 0.59$\times$10 $\textrm{cm}^2$/s. From these analysis, the power function, G, was also calculated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.275-280
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• 2002

The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid-stave chase synthesis for production of high temperature superconductor materials were discussed. Oxide superconductors with general formula of $ReBa_2Cu_3O_{7-x}$ (Re=Y, Sm) haute been made by using barium oxide initial powder instead of traditional barium carbonate. Phenomena observed during the grinding of the reactants mixture are presented. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.

• Journal of Hydrogen and New Energy
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• v.33 no.1
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• pp.77-84
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• 2022

The experimental work has been carried out for the study of pyrolysis of oil samples used in industrial and utility boilers in Korea. For five oil samples, the characteristics of pyrolysis have been investigated with a thermogravimetric analyzer (TGA), and their kinetic parameters were obtained and compared each other. The rate order of pyrolysis rate for five oils were as follows: by-product fuel oil, pyrolysis oil, diesel, a heavy oil and refined oil. The pyrolysis of refined oil has been successfully described by the three step, first order reaction model while the single step reaction model has been used for other oils. For the reaction temperature over 550 K, the reactivity of refined oil was very poor compared with other oils.

• Fire Science and Engineering
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• v.31 no.6
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• pp.23-32
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• 2017

Foam block, popularized as the self-interior goods, is susceptible to fire since the main material is the polyethylene flammable synthetic resin. However, it is widely used in homes, offices, and multi-use facilities. In order to understand the fire characteristics of the foam block, two kinds of foam blocks sold in the market (non-fire retardant and fire retardant) were evaluated according to standard of KS F 5660-1 (Reaction to fire test). In addition, the hazard analysis of the gas generated by the combustion of the specimen was performed using the FTIR gas analyzer. The cone calorimeter test showed that the ignition and flame combustion of both two specimens were burned as soon as the radiant heat blocking device was removed, and it was confirmed that the flame could become a rapid propagation factor during the fire. The analysis of the combustion gas through the FTIR gas analyzer showed that both the carbon dioxide and carbon monoxide classified as the common combustion gases and the acrolein, ammonia, and hydrogen cyanide causing serious damage to the human body were detected substantially. This study showed that a foam block product has high ignitionability and generates toxic gases. Hence, it is urgently required to establish the standards used for properly classifying the combustion characteristics of the material on the basis of the use conditions of a foam block product and to prepare the standards on the purpose of use.