A parametric study has been made numerically on the thermal incineration of CF4, one of the perfluorocarbons (PFCs) emerging recently as issues of public concern in a practical CDM incinerator developed for the thermal destruction of HFC-23. In doing this, a turbulent combustion model of the fast combustion approximation is reasonably assumed using the typical auxiliary fuel, CH4, for the supply of the heat, and the necessary species of hydrogen and oxygen atom. In addition, the performance of the stoichiometric gas mixture of hydrogen and oxygen (H2+ 1/2 O2) was examined as a special auxiliary fuel not only in order to enhance the thermal destruction efficiency but also the reduction of the CO2 emission by the elimination or the reduction of the auxiliary fuel CH4 in this incineration process. The calculation results showed that the thermal destruction efficiency of CF4 using methane as an auxiliary fuel increases with the amount of methane. However, the thermal destruction efficiency did not reach a satisfactory level (i.e., < 95%), even with the application of a CH4 amount more than four times of the stoichiometric value. This is explained by the improper turbulent mixing effect between CH4, CF4 and air especially in a large scale practical incinerator employed for the destruction of HFC-23. For the case of H2+ 1/2 O2 as the auxiliary fuel, however, the thermal destruction efficiency, surprisingly, reached almost 100%, which shows the high potential of the thermal destruction of CF4 by the use of HHO gas. Further, a detailed evaluation for the effect of the turbulent mixing on the thermal destruction of CF4 will be quite necessary, considering operating conditions together with the type of auxiliary fuels.

These days, the development of various pre- and post-combustion techniques has been pursued in order to reduce the emission of CO2 in the fleet of coal-fired power plants, since it is of great importance to each country’s energy production while also being the single largest emitter of CO2. As part of this kind of research efforts, in this study, a novel burning method is tried by the co-burning of the pulverized coal with the stoichiometric mixture of the hydrogen and oxygen (H2+1/2O2) called as HHO. For the investigation of this idea, the commercial computational code (STAR-CCM+) was used to perform a series of calculation for the IFRF (International Flame Research Foundation) coal-fired boiler (Michel and Payne, 1980). In order to verify the code performance, first of all, the experimental data of IFRF has been successfully compared with the calculation data. Further, the calculated data employed with pure coal are compared with the co-burning case for the evaluation of the substituted HHO performance. The reduced amount of coal feeding was fixed to be 30% and the added amount of HHO to produce a similar flame temperature with pure coal combustion was considered as 100% case of HHO addition. This value varies from 100 to 90, 80, 60, 50, 0% in order to see the effect of HHO amount on the performance of pulverized coal-fired combustion with the 30% reduced coal feeding. One of the most important thing found in this study is that the 100% addition of HHO amount shows approximately the same flame shape and temperature with the case of 100% coal combustion, even if the magnitude of the flow velocity differs significantly due to the reduced amount of air oxidizer. This suggests the high possibility of the replacement of the coal fuel with HHO in order to reduce the CO2 emission in pulverized coal-fired power plant. However, an extensive parametric study will be needed in near future, in terms of the reduction amount of coal and HHO addition in order to evaluate the possibility of the HHO replacement for coal in pulverized coal-fired combustion.

Proper management of refrigerant mixtures containing chlorine and fluorine are gaining worldwide interest in the recent years as, they contribute to global warming and ozone depletion. according to the Montreal Protocol, developed nations have substituted HCFCs in refrigerators and air conditions synthetic greenhouse gas (SGGs) refrigerants such as, R-10 (CCl4), R-23 (CHF3), and R-134a (CH2FCF3). SGGs contribute to the increasing global warming potential. incineration, conventional treatment method of R-134a leads generation of Freon gas, due to excess air during the deacon reaction and due to the flame inhibition of the halogen compound. Therefore, this study proposes on the effective thermal treatment (high-temperature pyrolysis) of R-134a using numerical analysis. R-134a is usually known to have reaction characteristics which degrade only at temperatures reaches 800℃ and contains sufficient moisture in the furnace, HFC-134a refrigerant is treated efficiently by following chemical reaction. C2H2F4+4H2O → 4HF+3H2+3CO2, 4HF+2Ca(OH)2 → 2CaF2+4H2O in this study numerical calculation is performed for the relevant variables. As a result, very positive preliminary results showed about HFC-134a refrigerant treatment. Base on this, in the following study, organized variable research and demonstration experiment will be performed.

The world consumption of the coal has been increased very sharply during past few years result from oil exhaustion, fluctuation in the price of oil and low price competitiveness of alternative energy. The International Energy Agency (IEA) has estimated that coal will be available for over 110 years, with coal reserves of close to 860 billion tons. The pulverized coal is blended coal powder that the particle diameter under 10μm. It has advantage of combustion efficiency and flame stabilization. The use of coal blends is becoming increasingly common in pulverized-coal power plants because it improves the economic performance of these plants by diversifying the fuel range. However, although blending can improve combustion behaviors and decrease gaseous pollutant emissions, it has difficulty of design and operating the pulverized coal combustor because despite the small particle size, combustion process of pulverized coal is exceedingly complex. Because of that the detail study on the combustion characteristic is important for increasing of efficiency. As a base investigation for numerical calculation of pulverized coal combustion, this study verified validity of models and compare the numerical calculation results with the experimental results.

Considering the high potential of the widely-used halogenated hydrocarbons on the global warming and ozone depletion, the development of effective thermal destruction methods of these compounds are quite urgent and indispensible. As part of the research efforts of this area, the destruction of CCl4 and flame characteristics have been investigated numerically by the co-firing CCl4 with CH4 in an industrial LNG-fired combustor as a function of molar ratio of the CCl4 to CH4 using a commercial code of STAR-CCM+. Considering a broad range of Damkohler number associated with the process of intensive CHCs (Chlorinated hydrocarbons) combustion with auxiliary fuel together with the inhibition reaction especially near flammability limits, a proper combustion modeling of CCl4 thermal destruction is quite desirable. In this study, however, after careful review of the literature about the flame characteristics of halogenated hydrocarbon together with the previous study about the modeling of the CCl4 flame based on the data of burning velocity, the eddy breakup turbulent combustion model was employed since it is quite reasonably assumed that chain branching reaction looks dominant in most flame region over the halogenated inhibition effect in strong turbulent reacting flows. One of the most useful results based on this study is that; without any incorporation of flame inhibition effect, the length of co-fired flame increases steadily as the ratio of CCl4 to CH4 (R) increases from 0.0, 0.1, 0.2 to 0.5, and 1.0 together with the increase of the maximum flame and exit gas temperature. The reason of the increase of the flame length with the increase of flame temperature can be explained by the presence of the additional CCl4 fuel with low heating value. Further a detailed discussion has been made on the thermal destruction of CCl4 together with the Cl2 concentration by Deacon reaction.

In this study, the waste gasification gas was co-fired with LNG and water electrolysis gas (or stoichiometrically well-mixed hydrogen oxygen gas) in order to see the change of flame characteristics compared to the standard case of wellknown LNG flame. In detail, a numerical study was made to figure out the fundamental combustion characteristics ofthe waste produced gas blended LNG or hydrogen-oxygen mixture gas flame in an existing industrial LNG combustor.As a preliminary study, the mixture of 70% synthetic gas blended with 30% LNG or hydrogen-oxygen mixture gas wascompared with pure LNG fuel with maintaining the same total input of heating value. Especially, the reason to includethe hydrogen-oxygen mixture gas, that is, the mixture of H2 and 1/2 O2, as a fuel is following:the hydrogen-oxygenmixture gas has a rather high heating value since it does not need air as oxidizer, which consists of 79% N2 as inertmaterial. The result shows that the case of mixture fuel with LNG exhibits more broadening flame shape than the 100%LNG flame. Further, it is observed that there is a phenomenon like a disappearance of CTRZ (Central ToroidalRecirculation Zone) and flame extinction showing partial lift-off of flame around strong swirl flow near burner. This kindof observation appeared in the case of blended fuel mixture is considered probably due to the increased effect of velocityand turbulence stress caused by the mass increase by the addition of low calorific fuel. However, the case of mixturefuel with hydrogen-oxygen mixture gas and water vapor does not show any flame instability phenomenon due to increasedflow rate as in LNG case.