Note: Descriptions are shown in the official language in which they were submitted.
8 S 7
~ his invention relates to appara-tus for separating
mixtures o~ materials by means of rectification, particularly
for separating such mixtures o~ ~aterials the boiling points
of which lie ~ery close to one another.
Qften the differences~ iIl the properties of the
~aterials to be separated are so small that even using
vacuum,excess pressure, ex~rac~ve distillation or reactive
distillation, separation is extraordinarily difficult.
Rectification columns for separati~g such mixtures have a
high ratio between the internal mass flo~r ~of the liquid
or of the gas) and the mass flow of the mixture to be
separated~ Often very many separation stages are necessary,
which necessitates a large constructional height of the
columns. Additionally, the separation must often be carried
out under low pressure (vacuum) which makes the ratio of the
volume flow of the gas to the volume flow of the liquid very
large. ~or economicall~ carrying out the separation of
materials the pressure drop in the column and the quantities
of materials to be transported s~ould be as low as possible.
Various rectification columns for facilitating the
separation of materials from mixtures of materials with
very similar properties are known. In these previously
known rectification columns it is dif~icult to g~aran-tee a
substantially constant ratio of gas stream to liquid stream
at each place of the horizontal cross section. Additionally
costly fillings must be used in order to guarantee good
wetting with the li~uid, which are easily fouled up.
.
; .
''" .
57
The object of the,pres,ent inyention consists in pro-
viding a rectification column w'nich enables simple and
economic separation of mixtures of materials with boiling points
which lie very close to one another and which have very similar
properties. This is achieved according to tlle invention by a
rectification column which has individually parallel connected
mass transfer pipes of which each has its own reflux condenser
and its own reflux evaporator.
The expression mass transfer pipe is used to denote
a vertically arranged tube in tne interior of which gas flows
upwards while on the waIls the liquid flows downwards, by means
of whicil mass transfer can take place between liquid and gas.
The feed of tlle mixture of the material to the individual
mass transfer pipes and the removal of the at least partly
separated materials from tlle mass transfer pipes takes place in
the gas phase. By means of this the distribution over the in-
dividual mass transfer pipes and ~he collection of the rectified
products is facilitated.
~ t the upper or lower end respectively of -the mass trans-
f,er pipes, the wall of the tube serves simultaneously as thesurface of the reflux condenser or of the evaporator, res-
pectively.
According to a preferred embodiment the inner surface
of the mass transfer pipe is so treated that substantially
even wctting is achieved. This can be achieved especially by
providing axial or helical grooves on the tube wall.
The :~eed of the mi~ure of materi.als to ~e separated
and the removal of the rectiflcation products from the in-
dividual mass trsnsfer pipes is effected. through opening~
and/or through tubes whiGh are arranged in t~e interior of the
mass -transfer pipes and w~ich have openings at suitable
places.
~ he invention is described by way o~ example with
reference to an embodiment and to the accompanying dral~ings~
in which:
~ igure 1 is a longitudinal section through an
individual mass transfer pipe;
~ igure 2 is a longitudinal section through the
separating column, and
. ~igure 3 i5 a c.ross-section through a part of the
wall of a mass transfer pipe.
mass transfer pipe 1 consists of an outer tube
2 and an innex tube 3 arranged concentrically theretoO
~ube 3 is provided with two openings 4, 5. Concentric
tube sections 6 and 7 of smaller diameter than tube 3 are
located at both ends of the mass transfer pipe 1. A further
concentric tube section 8 is arranged at the bottom between
the tube 2 or 3 and the tube sections 7. ~he sealing of
various spaces is effected b~ means of bungs,9 to 13. ~he
bungs 10 and 13 are pro~ided with labyrinth throttling sections
14, 15. On the inner tube 3 there are affixed centering pins 16.
. .
-- 4 --
.
.
S7
The interior spaces of all interior tubes 3 debouch
upwardly into a first collector 17 with a pipe 18 and downwardly
into a second collector 1~ with a pipe 20. The intermedia-te
spaces between the outer tubes 2 and the inner tubes 3 debouch
upwardly into a collector 21 with a pipe 22 and below into a
collector 23 with a pipe 24. Below the collector 21 there is
located the jacket space 25 of the condenser which is divided
by means of a baffle 26 and whicll is provided with a cooling
water inlet pipe 27 as well as a cooling water outlet pipe 28.
Above the collector 23 there is located the jacket space 29 of
an evaporator which is provided with a steam pipe 30 and a con~
densate pipe 31.
The inner surface of the outer tube 2 is provided over
its entire periphery and over the entire length of the tube
with axial or helically shaped grooves 32 (see Figure 3). The
vapour arising condenses above on these surfaces and the conden-
sate flows downwards at the base of the groove. In the region
of the evaporator this liquid is wholly evaporated and the
vapour arising then flows upwards in the annular space between
the outer tube 2 and the inner tube 3 in the opposite direction
to the liquid. By means of this mass transfer takes place
between the liquid and the gaseous phases.
In the example described herein two feed streams are
illustrated. The higher introduced feed stream flows through
the pipe 18, collector 17, tube section 6, the interior of the
inner tube 3 and opening 4 into the annular space between the
outer tube 2 and the inner tube 3, where it mixes with the
~ - 5 -
ii7
previously mentioned upwardl~ flowing vapour. The lower
introduced feed stream flow through the pipe 20 7 collector
19, pipe section 7, the interior of inner tube 3 and opening
5 likewise to -the annular space between the outer tube 2
s
and the inner tube 3, wh.ere it likewise mixes with the
pre~iousl~ mentioned upwardly flowing vapour~
~ he removal of the head product takes place via
the labyrinth throttl.ing section 14, the Gollector Zl and
the pipe 22. ~he bottoms product is removed via the baffle
which is constituted by the tube section 8 for holding back
any liquid which comes to be collected there and fur-ther via
the labyri~th throttling section 15, the collector 23 and
the pipe 24.
~ he cooling water is fed through the pipe 27 and
the jacket space 25 of the condenser and flows, cooling the
upper part o.~ the outer tube 2, in the direction shown
by the arrow to the outlet .through the pipe 2~. ~he heati~g
steam is fed throu~h the pipe 30 to the jacket space 2~
of the evaporator and condenser on the outer surface of
the lower part of the outer tube 2~ '~he condensate is fed
~way by the pipe 31~ -
. _ .
- 6 -
.- ~:. ~ ;
.-~ . .: ,
~ ' ~
