Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The inventlon relates to a device for the control o~ ~n
ammonia converter etc., with a process gas lnlet and a pro~ess ya~
outlet, at least one heat exehanger and at lea~t on~ cataly3t b~
as well as another gas inlet, and a central pipe, as well a~ a
process ya,s supply line to the heat excllanger or, re~pectively,
catalyst bed, Wit}l the heat exchan~er placed in a clynamlc~l]-y
balanced posltion wlt,h ~egarc1 ~,o the cent,ra:L pipe, whl~e the ~
catalyst hed 1~ llkewise placed ln a clynamlcally halanced positlon
around the best exchanger.
As is known, devlces for effecting exothermic, catalytic
gas reactions for ammonia or methanol synthesis are designed so as
to allow, for example, cold feed gas to be fed into the pressure
vessels, for control purposes, via a separate gas supply, to join
the process gas stream in a channel of that heat exchanger whlch
is allocated to the first catalyst bed, with two catalyst beds
with heat exchangers - each of the latter being placed
concentrically - envisaged in the pressure vessel, as in the case
in the well-known embodiment. This result ~rom German patent No.
33 43 114 of the applicant.
According to German patent No. 27 10 247 there is a
well-known process, in which the process gas stream is composed of
two part streams, with at least one of the lat~er being acliustable
with regard to temperature and/or quantity in order to achieve the
desired process conditions. In every case, the combination of the
gas streams is effective prior to entry into the first catalyst
bed.
These known control facilities do not allow for the
control gas to completely bypass - by means of a bypass contxol
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clevice - the first catalyst bed and the heat exchanyer allocatet~
to i~ so as to admix with the gas stream whlch has alread~J pa~secl
through the first catalys-t bed and the as50cia~ed heat; ex~hanyer.
The aim o~ the inventlon ls to provide a ~olution
enabling control gas~ quench gas or some of the process ga,~ to be
~ed into the re~pe~tive ~a~ str~am ~t dl~ferent temper~ture~
and/or under variou~ condltlons at any place :Ln th~ reac~or. Th0
solution to be adopt~d i~ to be deslgned in suc~h a way as to make
it possible for the admixture or, the bypass pipe to be completely
shut or partly opened or, completely opened as desired.
The invention provides device for the control of an
ammonia converter or the like havincJ a process gas inlet, an
outlet, at least one heat exchanger, at least one catalyst bed,
another gas supply line and a cen~ral pipe, a process gas supply
line to the heat exchanger, tha ca~alyst bed, said heat exchanger
being heated in a dynamically balanced position with regard to the
central pipe, while the catalyst bed is likewise located in a
dynamically balanced position around the heat exchanger,
characterized in that, for temperature control purpose, the
control gas feedpipe is a central pipe extencling through the whole
length of the heat exchanger (4, 5 or 6) and being fitted, at the
bottom end thereof with adjustable outlets (18) to allow at least
partial admixture of control gas with the process gas stream
before the latter passes through the catalyst bed (4), ancl~or to
permit admixture of the control gas stream with the process gas
stream after the latter has passed through the catalys~ bed (~)
and the heat exchanger (7).
With the solution, the central, adjustable pipe makes it
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possible, for example, for the control gas to be fed, in an
extreme posltion, at rlght angles ~hrough the heat ex~hanger into
the process gas stream only after the latt~r has already pa%sed
through the first catalyst becl, fo1lowed by the heat exch~n~er,
i.e. it can, for e~ample, be fed into ~he CJaS stream wh:Lch 1~ ~fJ
char51e th~ followincJ ~c~aly~l, becl,
An embodlment of the lnventlon is desi~ned in ~!uch a wa~y
that the guide pip2S for the process gas runniny through the heat
exchanger surround the central, adjustable pipe at a distance from
the latter. The advantage of this is the relative simplicity of
desiqn both of the heat exchanger and the centrally extending
bypass pipe. As a rule, special elbows or similar components can
be dispensed with as a result.
A particularly favourable embodiment of the invention
also provides for the distribution holes of the central pipe to be
synchronously adjustable interdependently. This type of control
allows not only for some control positions to be attained - in
that, for example, one outlet of the control pipe is fully closed,
while the other is fully opened and vice versa - but also for any
intermedi-
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ate position to be adjusted synchronously, i.e. for con~rol gas to
be admixed to existing process gas streams in any partial quantity.
For flow control purposes, it is advisable to fit the central pipe,
at the bottom end, with adjustable openings via a piston with axial
o~enings, the former opening into a flow channel 'or he recycle
gas. This type of control facility can be particularl~l easily ef-
fected, although the invention is not restricted to this variant
Thus the piston, with its aY~ial openings, can either, by way of
pushing, partly open or close the lateral openings in tne lower
part of the central pipe. The same effect can also be achieved by
way of rotation, given the appropriate piston design.
The above embodiment of the invention, which provides ~or one part
of the control facility to be designed as a cylinde-~ makes it ai-
visable to design the bottom front end to be fully sealable by
means of a sealing element lin~ed to the cylinder, as is likewise
envisaged by the invention. It is especially with several catalyst
beds, with heat exchangers fitted concentrically insiàe, that the
invention provides for the central pipe and/or the actuator of the
adjustable outlets to run through at least one more heat exchanger.
In this context, the above-mentioned once again applies, i.e. the
fact that the specific advantage of the invent~on consists in the
simplici'y o' controlling con'rol gas streams, any situation being
precisely controllable owing to the fact that control gas streams
can always be employed ~here they are needed.
A more specialized embodiment of the invention envisages a control
element in the case of a cen~ra.l infiow of cold process gas into
the channel of ~he second heat e.~:chan~er, ~or cooling the vessel
shell, from below via a third catal st bed. This control element
allows the admixture o. at least par~ of the colder shell gas to
the process qas before the latter en.ers the third catalyst bed. In
this way, the colder shell gas cannot only be heated up in the tra-
ditional fashion via the second and the first heat exchanger. .~t
the same time, it is possible to use part o~ the control gas for
the third catalys~ bed. Vice versa, it is, o~ cou-se, possible to
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control, by means of these designs, the quantities of shell gas to
be fed into the upper first and second catalyst beds.
Finally, it may be of advantage if a second central pipe runs
through the first central pipe, with the former running to below
the following heat exchanger and serving to admix control gas to
the process gas stream before the latter reaches the third catalyst
bed.
At this point, mention must be made of the fact that the stepped
arrangement of concentric lines, which make it possible for several
cont-ol gas streams to be fed simultaneously, is not confined ~o
t~.is type of dual embodiment. Depending on ~he number of steps, se-
veral concentric lines of this type can be envisaged, too.
- In the following, the invention is desoribed in detail with the
help of drawings, which show the following:
Fig. 1 a cross-sectional view of a device in accordance with the
invention, with two catalyst beds and a control facility.
Fig. 2 a cross-sectional view of a different embodiment, with
three catalyst beds.
Fig. 3 a modified embodiment in accordance with the type of ar-
rangement illustraled in Fig. 2.
Fig. 4 another embodiment of the invention~
Fig. S a modified embodiment of a control facility in accordance
with the type of embodiment shown in Fig. a
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Device 1 consists chiefly of a pressure vessel 2, with the embod-
lment illustrated in Fig. 1 having two catalyst beds, t~e embod-
iments illustrated in Fig. 2-4 having three catalyst beds arranged
concentrically around the cen~re line. The upper and first catalyst
bed is marked 4, the second belng marked 5, and ~he lower and last
(in embodiments according to Fig. 2-4) being marked 6.
A first heat exchanger 7 is fitted inside the first catalyst bed 4
while a second heat exchanger 8 is fitted inside the second cata-
lyst bed 5 in embodiments according to Fig. 2-~, with heat exchang-
ers 7 and 8, in the latter case being connected in series as r~
gards their function. The catalysts including the heat exchangers
are surrounded by an encasing wall 9, whose ~imensions are such as
to provide for the for~ation of a continuous annular space 10 be-
tween the inner surface of the vessel wali and the encasing wall 9.
The e~bodiment illustrated in Fig. 1 provides for a cooling gas to
enter device 1 at the top via a noz~le 11, 10wing through an annu-
lar space 10 and escaping, together with the recycle gas, at the
bottom via a nozzle 12. The upper nozzle for the recycle gas is
marked 13. A pipe 14 is envisaged to be concentrically fitted in-
side the heat exchanger 7 and to be filled with gas for control
purposes via an intake nozzle 15.
This central pipe joins a distribution chamber 16 for the process
gas which has already passed through the first catalyst bed 4 on
the inside and through the heat exchanger 7 on the outside.
The invention provi~les for another distribution chamber 17 to be
fi~ted below the first heat e~:changer 14 and separated gas-tight
from the distribution chamber 16, into which the ~rocess gas flows
after passing through the guide tubes 30 of the heat exchanger 7,
in order to be channelled from there to the catalyst bed 4. In this
area, the central pipe 14 has openings 18, through which at least
some of the control gas passing through 'he control pipe 14 can
flow into the distri~ution cnamber 17. By means of a contro.l
rod 19, whicn is r-it.ed with the s~op piston ^û with axiai openin~s
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in the area of the slots 18 and with a stop plug 21 at the bottom
free end, the control gas can be adjusted and part streams can be
dis~ributed on a percentage basis to the distribution chambers 16
and 17.
The mode of operation is as follows:
If, for example, the control rod 15 is raised as shown by the dou-
ble arrow 22, the plug 21 shuts off the bottom free end OI the cen-
tral pipe 1~, while the slots 18 are fully opened. The control gas
now flows entirely through the slots 18 into the space 17, i.e. it
mixes with the process gas stream before the la'ter ?asses through
the catalyst bed 4.
If th^ control rod (19) ls moved down, the stop plug 21 will open
'_he bottom o~ening-to-the--extent that the slots 18 are being --
opened, so that the latter are fully closed in the bottom dead cen-
tre oosition, while the bottom onening of the central ~ioe 14 is
fully open at the dist~ibution chamber 16, so that the entire con-
trol gas stream is fed into it as a bypass mixing with the process
gas stream which has passed through the first catalyst bed on the
inside and th~ough the heat exchanger 7 on the outside.
Functionally identical Darts of the following embodiments are
marked with the same reference number, supplemented by lo~er-case
letters.
The embodiment shown in Fig. 2 has the sa~e basic arrangement, the
only variation being that the process gas is centrally feà from
above as a Dart stream -~ia a pipe nozzle 13a, another ~ar~ being
fed via a pipe nozzle lla as a cooling shell gas which passes, via
a riser 23, the centre of the third catalyst bed 6a from below, in
order to low first through the second heat exchanger ~ and then
through the miY~ing chamber 17a. Here again, the control gas is dis-
tributed in the same way as in the embodiment iilustrated by
Flg. 1.
RV~?~002Q71137
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The embodimen1 illustrated by Fig. 3 is similar, although, in this
case, the recycle gas is fed, in three part streams, through one
upper feed no~zl~ 13b, one upper first shell gas fe~d no~zle llb,
as well as, additionally, one lower shell gas feed nozzle 24. In
this embodiment, the shell ga$ streams ed from above and below are
collected by m~ans of radial headers 25 below the second heat 9X-
changer 8b in a joint channel 26 and subsequently channelled up-
wards. In this embodiment, too, the admi~ture OI control gas is ef-
fected ln the same way.
A modified version of the control device, as illustrated ~y Fig. 4
consists in that the control rod l9c runs th-ough the entire l--ngth
of the iirst heat excnanger 7c and the second heat exchanger 8c,
adjusting the supply of the shell gas, which is fed from below via
the central supply lins 23c, to the channel 26c of the second heat
exchan~er 8c. Here, for e~apmle, a hol-lo~ cylinder sealing element
is envisaged, bearing reference number 27. If it is lifted, it will
enable at least one part stream to escape laterally and to mi~ ~ith
the process gas direct which will subseauently cha~ge the lowe- and
third catalyst bed 6c. If the control rod is moved downwards, the
hollow cylinder 27 will only allow the shell gas to pass through in
an u~ward clirection, no admixing being possible in this case.
Finally, Fig. 5 illustrates a possibility of feeding in several
control gas streams. In this drawing, it is merely the principle of
the control facility w`nich is illustrated. The central pipe, marked
l~d, contains another central pipe 28 to the extent that the latter
ends in the area of the first channel 25d of ~he second heat ex-
changer 8d. This embodiment envisages radiai distribuiion lines 29,
which ma~.e it possible ~or control gas to be admi~ed .to ~he gas
stream escaping rom the second heat e~changer 8d in order to be
channelied to the third catalyst bed 6d.
The above embodiments of the invenrion can, of course, be modified
in many respects without afîecting the basic idea. Thus flow ad-
justment for each channel ~ay be designed witn piston/cylir.der ele-
ments etc. - in the e~odimenl illustrated by ~g. 5, ~or e~ample,
in conjunc.ion with ~he cen{.ral pipes 20 and i4d.
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