Page 118 - Packed bed columns for absorption, desorption, rectification and direct heat transfer
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(5)
where fa is the attenuation coefficient of the medium;
/- length of the attenuating medium.
From Eq. (5) it follows:
(6)
Depending on the constituting material of the attenuating medium, the
attenuation A can vary spatially across the column cross section. From the
measured spatial variation of A, the spatial variation of attenuation coefficient
jUj can be reconstructed by the tomographic reconstruction algorithm.
When the gamma-ray passes through a column filled with dry packing,
the measured attenuation can be expressed in terms of the attenuation
coefficient as
f*air air f*p*p f*w w" v'J
The indices air, p and w correspond to air, packing, and column wall,
and Imfd - the intensity of the gamma-ray after the dry column.
In case of irrigated column the equation for calculation of the intensity
of the gamma-ray / re j after the column is:
-U-M -
where the index / corresponds to liquid, and reft- to irrigated packing.
Subtracting Eq. (6) from Eq.( 8) we get
