Page 110 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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- uniform distribution over the whole column cross-section in the operational
3 3
range of the distributor from 5 to 250 m /{m h);
- no small droplets are formed in the gas phase.
The uniform distribution is determined by the fact that the pressure drop
of the pipes and the dynamic pressure of the flow in them can be neglected in
comparison to the pressure drop of the orifices.

2.1.1.3.2, Supporting grid for the packing
A very important requirement to the supporting grid is that its free
cross-section should not be smaller than the free cross-section of the packing.
Usually it is built of vertical strips with a distance between them some smaller
than the packing diameter. If the two above mentioned conditions cannot be
fulfilled by a simple construction, it is possible to divide the grid into two grids,
lower, that supports the weight of the packing, and upper, that ensures the
necessary small distance between the strips.

2.1.1.3.3, Gas distributor
To ensure a uniform gas distribution even at the beginning of the
packing, the experimental installation should have a special distributor for the
gas phase. A construction for such a type of distributor for a 500 mm diameter
column is presented in Fig. 6. The gas distributor consists of two cylinders, (1)
and (2). There are 15 rectangular orifices (3), uniformly distributed in the wall
of the inner cylinder with a diameter equal to the column diameter. The height
of the orifice is 275 mm and the width is 18 mm. The distance between these
orifices and the column supporting grid is 205 mm. For another diameter of the
column, the dimensions mentioned above have to be changed proportionally to
the column diameter.

2.1.1.3.4, Gas/liquid phase separator at the points of measuring of the pressure
drop.
For correct measuring of the pressure drop of the packing it is important
to avoid the getting of the liquid drops into the impulse pipes connecting the
differential manometer. The same is also important for the impulse pipes to the
gas analyzer. The separator represented in Fig. 7 solves this problem.
To avoid the influence of capillary forces, the diameter of the orifice (2)
connecting the column with the separator should not be smaller than 10 mm.
The diameter of the separator space is between 30 and 50 mm.