a.)Hydrogen sulfide needs to be removed from natural gas prior to putting the ga
ID: 845304 • Letter: A
Question
a.)Hydrogen sulfide needs to be removed from natural gas prior to putting the gas into a pipeline. This separation can be accomplished by contacting the gases with water to selectively absorb the H2S. Therefore, you are interested in finding the mass transfer coefficient of H2S in water. Using a wetted-wall tube you contact pure H2S and water counter-currently, pure water is fed to the top of the column at a velocity of 0.31 cm/sec and the concentration of H2S in bulk water leaving the column is 10% the saturation concentration. Assume that the water forms a 0.11 cm thin film of water on the side of stainless steel pipe that is 0.5 cm in diameter and 6 cm long. What is the mass transfer coefficient of H2S in water for this geometry?
b.) Compare the mass transfer coefficient calculated from experiment above with that found from the correlation given below: kz/D=0.69(zv^0/D)^0.5
where k is the mass transfer coefficient, D is the diffusion coefficient of hydrogen sulfide in water, and v^0 is the superficial velocity of the liquid.
Explanation / Answer
If you look at the interficial solubility of the hydrophobic interactions in the contacting surface area, it becomes quite clear that a steady state analysis of this system is in order. Because the preferential diffusion of hydrogen sulfide occurs at a temperature differential of greater than 10 degrees fahrenheit under the above conditions, the pressure profile through the column must be considered. Theoretically, this question is answered by looking into the differential gradients moving through the column. The stainless steel material aspect of this problem is of the utmost importance, as the properties of the material permit such an exchange of H2S into water. The answer is .01327 cm/s . Hope this helps.
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