Kil Won Cho

Estimation of the heating value of oily mill sludges from steel plant

Heating values of oily mill sludges were measured and calculated. The calculated values with conventional equations showed severe discrepancies with measured ones. Most of the oxygen was confirmed to be associated with iron rather than with combustibles by a series of experiments such as proximate analysis, ultimate analysis, thermal analysis and chemical analysis. The heating value of the sludge was predicted well by using a modified Dulongs equation which ignores the oxygen content in the sludge.

Premixed combustion of coke oven gas in a metallic fibre mat

Combustion characteristics of liquefied petroleum gas (LPG) and coke oven gas (COG) in a metallic fibre mat were investigated experimentally to examine the effect of fuel change on surface combustion performance. It was found that the upper limit of surface loads representing the radiant mode is increased in the case of COG combustion. Mat temperatures were slightly lowered for COG combustion at low surface loads. The surface load showing the maximum surface temperature was shifted to a higher one for COG combustion. It was concluded that the range of surface loads for radiant mode combustion and the surface load for the peak surface temperature are mainly dependent upon the flame speed of the fuel used.

Transient one-dimensional heat flow technique applied to porous reactive medium

A transient one-dimensional heat flow technique was presented to measure the effective thermal conductivity of porous reactive media. The porous reactive medium was in contact with a flat thermistor in a cell, and vacuum was applied to remove the air and the moisture. Afterwards, ammonia atmosphere was maintained in the cell under a fixed temperature and pressure. A varistor with max. 100 Ω was used to equate with the resistance of the thermistor corresponding to the fixed temperature. The temperature increase of thermistor was 2–3 °C, which was sufficient to avoid the enthalpy effect due to chemical reaction. A graphite-CaCl2⋅nNH3 complex was given as a test specimen for the porous reactive medium. Measurements showed that the thermal conductivity of graphite-CaCl2⋅8NH3 complex has distinctively higher values than the graphite-CaCl2⋅4NH3 and CaCl2⋅2NH3 complex. The accuracy of measured conductivity was estimated to be within 10%.

Experimental study on the radiant tube burner with self-biased fuel nozzle

Full scale combustion tests for a conventional fuel nozzle and a self-biased one were carried out using a two-stage radiant tube burner as the basis. Compared with the conventional nozzle, more than 40% reduction in NOx emission was achieved with the self-biased nozzle. Under the same furnace temperature, the peak temperature was lowered and the temperature uniformity on the radiant tube was enhanced with the self-biased nozzle. The optimal design criteria for the self-biased nozzle were derived.

On the short-cut calculation of the air ratio in the case of firing fuels containing incombustibles

Abstract A short-cut equation for the calculation of the air ratio in the case of firing gases containing incombustibles has been derived on the basis of mass balance. The new equation requires the oxygen concentration and the amount of carbon dioxide in the combustion gas, theoretical oxygen and air requirements and the content of incombustibles other than carbon dioxide in the fuel for the air ratio calculation. By using the equation, a theoretically correct calculation of the air ratio has been enabled.