Abstract
The study focuses on the absorption rates of NO2, SO2 and a mixture of these two acid gases into urea solution in packed bed column. The absorption rate was studied as a function of absorbent temperature, urea concentration and acid gas concentration. The influence of liquid temperature between 10 - 40?C, urea concentration between 0.1 - 0.5 M and acid gas concentration NO2 between 100 - 1000 ppm (191 - 1910 mg/m3), SO2 between 500 - 2500 ppm (1310 - 6530 mg/m3) were investigated. The mass gas flow rate of 20.646 (kg/m2.min) at 25?C and the absorption rate were determined by measuring the NO2 and SO2 concentrations in the inlet and outlet streams of the absorptioncolumn. The absorption rate of SO2 increases with the decrease of temperature of absorbent (urea solution) and with the increase of the urea concentration. The presence of NO2 in the effluent gas stream lowers the absorption rate of SO2 in urea solution due to the fast reaction of NO2 with urea as compared with SO2. The absorption rate of NO2 decreases as the urea concentration exceeds 0.4 mol/l and for NO2 gas concentration of 100 ppm due to the decrease the diffusivity of the gas. The experimental data were analyzed using dimensionless analysis to find the correlation of mass transfer coefficient in the packed column Sh (H / dp)1.2 = 4.19*10–2 *(G' dp / μg)0.87 (μg / ρg DAB)0.60 The results confirmed the hypothesis that the absorption is accompanied with chemical reaction. Also it is found the increasing the temperature of absorbent solution the absorption rate of two gases is decreases. The mass transfer coefficient models are in good agreements with the Kramer’s equation.
Highlights
The harmful effects of the sulfur dioxide, SOx and nitrtogen dioxide, NOx, gases emissions in dense industrial and urban areas receive increasing attention especially where their production exceeds neutralization and dispersion forces [1]
The measurement concerned the study of the effect of the operation variables such as SO2 and NO2 level, urea concentration and operating temperature on the absorption rate of acid gas and their removal
The absorption rate of an acid gas (NO2 or SO2) is expressed as the equivalent moles of NO2 or SO2 that react with urea solution per unit interface area per unit time
Summary
The harmful effects of the sulfur dioxide, SOx and nitrtogen dioxide, NOx, gases emissions in dense industrial and urban areas receive increasing attention especially where their production exceeds neutralization and dispersion forces [1]. The release of SOx can be controlled by ammonia injection which relies solely on gas phase reaction in the presence of moisture to produce ammonium sulfate solid particles that can be captured by any other particulate collection device [3]. Heterogeneous reduction process of SOx by hydrogen sulfide into sulfur can be done in the presence of suitable solid phase catalysts. Methane can be used for the reduction of SOx into hydrogen sulfide on alumina as the catalyst. The hydrogen sulfide produced by this method is captured by amine scrubbing of the reduced gas stream. The higher concentration of sulfide obtained by heating the amine salt may be and economically converted to elemental sulfur via the Claus process [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
