• 청정기술
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• 제2권1호
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• pp.80-95
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• 1996

반건식 배연탈황공정에서 사용되는 spray dryer absorber(SDA)에 대한 수치모사를 행하였다. 기본 방정식으로는 기체와 액적의 각 성분들의 물질수지식, 에너지수지식과 액적의 운동 방정식등이 포함되었다. 만들어진 모델은 대부분이 기존의 SPRAYMOD-M보다 실제의 pilot plant data를 더 잘 모사하였다. 실제 pilot plant에서 사용되는 값의 범위 내에서 선정된 공정변수가 SDA의 성능에 미치는 효과를 계산하고, 이를 $SO_2$의 흡수속도, 배연기체의 체류시간, 그리고 액적의 건조시간 및 속도 등에 의해 검토하였다. 또 $SO_2$ 제거율을 두 개의 독립된 공정 변수의 함수로 구하였으며, 그 결과를 3차원 또는 2차원의 등가선으로 표시하여 SDA의 설계에 쉽게 적용될 수 있도록 하였다.

• 대한기계학회논문집B
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• 제21권8호
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• pp.1068-1076
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• 1997

Emission control of acid exhaust gases from coal-fired power plants and waste incinerators has become an increasing concern of both industries and regulators. Among those gaseous emissions, SO$_{2}$ has been eliminated by a Spray Drying Absorber (SDA) system, where the exhaust gas is mixed with atomized limestone-water slurry droplets and then the chemical reaction of SO$_{2}$ with alkaline components of the liquid feed forms sulfates. Liquid atomization is necessary because it maximizes the reaction efficiency by increasing the total surface area of the alkaline components. An experimental study was performed with a laboratory scale SDA to investigate whether the scrubbing efficiency for SO$_{2}$ reduction increased or not with the application of a DC electric field to the limestone-water slurry. For a selected experimental condition SO$_{2}$ concentrations exited from the reactor were measured with various applied voltages and liquid flow rates. The applied voltage varied from -10 to 10 kV by 1 kV, and the volume flow rate of slurry was set to 15, 25, 35 ml/min which were within the range of emission mode. Consequently, the SO$_{2}$ scrubbing efficiency increased with increasing the applied voltage but was independent of the polarity of the applied voltage. For the electrical and flow conditions considered a theoretical study of estimating average size and charge of the atomized droplets was carried out based on the measured current-voltage characteristics. The droplet charge to mass ratio increased and the droplet diameter decreased as the strength of the applied voltage increased.

• 대한기계학회논문집B
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• 제22권8호
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• pp.1111-1120
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• 1998

Spray Drying Absorber(SDA) system, where the combustion product gas is mixed with atomized limestone-slurry droplets and then the chemical reaction of $SO_2$ with alkaline components of the liquid droplets forms sulfates, has been widely used to eliminate $SO_2$ gas from coal fired power plants and waste incinerators. Liquid atomization is necessary because it can maximize the reaction efficiency by increasing the total surface area and dispersion angle of the alkaline components. First, numerical calculations using FLUENT are carried out to investigate $SO_2$ concentration distribution and thus to calculate $SO_2$ removal efficiency. So to attain the optimized spray conditions, then an electrostatic spraying system is set up and spray visualization is performed to show the effect of an electric field on overall droplet size. Next, the effect of an electric field on the concentrations of $SO_2$ is experimentally examined. Field strength is varied from -10 kV to 10 kV and configurations of conduction charging and induction charging are utilized. Consequently, the electrostatic removal efficiency of 501 increases about 30% with the applied voltage of ${\pm}10kV$ but is independent of polarity of the applied voltage. It Is also found that the conduction charging configuration results in higher efficiency of $SO_2$ removal that the induction charging configuration. Finally, the effect of slurry temperature on $SO_2$ removal is studied. The temperature influences on the electrostatic removal efficiency of $SO_2$.