Separation TE

chapter $($

chemical engineering

Diffusion of Methane Through Nondiffusing Helium. Methane gas is diffusing in a straight tube $0\mathrm{.}1m$ long containing helium at $298K$ and a total pressure of $1\mathrm{.}01325{10}^{5}Pa.$ The partial pressure of $C{H}_4$ at one end is $1\mathrm{.}400{10}^{4}Pa$ and $1\mathrm{.}333{10}^{3}Pa$ at the other end. Helium is insoluble in one boundary, and hence is nondiffusing or stagnant. The diffusivity is given in Table $6\mathrm{.}2-1.$ Calculate the flux of methane in kgmo$\frac{l}{s}*m^2$ at steady state.

$D_{AB}=0\mathrm{.}675{10}^{-4}\frac{m^2}{s}$

$N_A=\frac{D_{AB}P(P_{A_1}-P_A)}{RTZ{P}_{BM}}$

$P_{B_1}=101325-14000$

$P_{B_1}=87325P_9$

$P_{B_2}=101325-13330$

$P_{B_2}=87995Pa$

$P_{BM}=\frac{87995-87325}{ln(\frac{87995}{87325})}$

$P_{BM}=87659\mathrm{.}57Pa$

$N_A=\frac{0\mathrm{.}6751_0^{-4}101325(14000-13330)}{831452980\mathrm{.}187659\mathrm{.}5}$

$N_A=2\mathrm{.}1{10}^{-8}$kgmo$\frac{l}{m^2}\mathrm{.}5$