Note: Descriptions are shown in the official language in which they were submitted.
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1
HEAT EXCHANGER
Summary of the Invention
The invention relates to a heat exchanger, in particular for a synthesis gas
installation, for the (indirect) heat exchange between a first and a second
flowing
medium, in particular in the form of feed water and synthesis gas. In
particular, the
invention relates to a heat exchanger comprising: a shell which extends along
a
longitudinal axis and bounds a shell space for receiving the first medium, a
tube space,
surrounded by the shell space, for receiving the second medium, and a pass
baffle,
which is arranged in the shell space and extends along the longitudinal axis,
for directing
the first medium, carried in the shell space, along the longitudinal axis.
Such a heat exchanger has at least one pressure-bearing shell, which is made
to
extend along a longitudinal axis and bounds a shell space for receiving the
first medium,
and also has a tube space, which is surrounded by the shell space and in which
the
second medium is conducted, so that the second medium, carried in the tube
space, can
enter into indirect heat exchange with the first medium, on the shell side. To
allow the
first medium to be conducted through the shell space (and back) along the
longitudinal
axis, a longitudinal directing panel is provided, made to extend in the manner
of a sheet
along the longitudinal axis and generally produced from a metal (pass baffle).
In other
words, the pass baffle divides the shell space into two portions, a first
portion and a
second portion, that run parallel to one another along the longitudinal axis,
in order to
extend the flow path of the first medium in the shell space and thereby
intensify the heat
exchange. Such a heat exchanger is known, for example, from US 4,778,005.
It is of great importance here that, when the heat exchanger is operating in
the
way intended, as far as possible there are no bypassing flows that reduce the
effectiveness of the heat exchange. In the case of the known heat exchanger,
there is
particularly the problem that, when there is a failure of the sealing of the
pass baffles
with respect to the surrounding shell, such bypassing flows of the first
medium can
occur, leading to a significantly lower heat exchange of the first medium in
the shell
space, which correspondingly reduces the effectiveness of the heat exchange.
Such a
heat exchanger is therefore not suitable in particular for applications at
high pressures
(for example in synthesis gas installations).
Against this background, one aspect of the present invention is to provide a
heat
exchanger that is improved with respect to the aforementioned problem.
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Upon further study of the specification and appended claims, other aspects and
advantages of the invention will become apparent.
These aspects are achieved by a heat exchanger wherein the pass baffle is
welded to the shell.
In accordance with the invention, the pass baffle of the heat exchanger is
welded
directly to the shell (i.e. is connected directly to the shell by means of a
welded
connection which may comprise a number of weld seams). This welded connection
is
impermeable in particular to the first medium, so that the first medium cannot
pass from
the first portion of the heat exchanger into the second portion of the heat
exchanger by
way of that welded connection. This solution according to the invention
consequently
makes it possible in principle to reduce the risk of so-called bypassing
flows, and
therefore have much better control over the process.
The shell preferably has a first shell part, which is made to extend along the
longitudinal axis, and a second shell part, which is made to extend along the
longitudinal
axis and lies opposite the first shell part transversely in relation to the
longitudinal axis.
The two shell parts are connected (welded) to one another by way of the pass
baffle.
The shell parts are preferably parts in the form of half shells, in particular
in the form of
halves of a cylindrical shell (of a straight hollow-circular cylinder).
The pass baffle is preferably formed such that it is made to extend
longitudinally
along the longitudinal axis and thereby preferably has a sheet-like
rectangular form, with
two peripheral regions lying opposite one another transversely in relation to
the
longitudinal axis and running along the longitudinal axis. These two
peripheral regions,
respectively, have a first side, which faces the first shell part, and a
second side, which
is remote from the first side and faces the second shell part.
The two shell parts preferably respectively have a first end face, which is
made to
extend along the longitudinal axis. The first shell part is preferably
connected by its first
end face, made to extend along the longitudinal axis, to the first side of the
first
peripheral region by way of a first weld seam. The second shell part is
preferably
connected by its first end face, made to extend along the longitudinal axis,
to the second
side of the first peripheral region of the pass baffle by way of a second weld
seam. In the
same way, the second end faces of the two shell parts may also be respectively
connected to the second peripheral region of the pass baffle.
The weld seams preferably completely fill intermediate spaces between the end
faces of the shell parts and the respective peripheral regions of the pass
baffle. That is,
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in a cross-sectional plane running perpendicularly in relation to the
longitudinal axis of
the shell, the weld seams connected to the peripheral region of the pass
baffle are
respectively formed continuously (in one piece), so that the weld seams
respectively
have an outer side and an inner side. The outer side faces an outer space
surrounding
the shell, is adjacent thereto and goes over into an outer side of the
respectively
assigned shell part of the shell. The inner side faces the shell space, is
adjacent thereto
and goes over into an inner side of the respectively assigned shell part of
the shell that
faces the shell space and goes over into the respectively adjacent side of the
pass
baffle.
In this case, in a cross-sectional plane running perpendicularly in relation
to the
longitudinal axis of the shell, the weld seams in question may initially
narrow towards the
shell space and widen again, in particular in a step-shaped manner, in the
region of an
inner side, facing the shell space, of the respectively assigned shell part,
so that the
weld seams concerned respectively reach around a periphery of the respectively
assigned end face of a shell part.
Furthermore, the thickness of the pass baffle may be narrowed towards an outer
periphery, i.e. in particular at the two peripheral regions, that is to say
between end faces
opposite from one another of the shell parts, or as an alternative to this the
pass baffle
may have a constant thickness in the region of the peripheral regions.
For stiffening the shell, in particular for strengthening the connection
between the
shell parts of the shell, the heat exchanger has at least one stiffening ring,
which runs
around on the shell transversely in relation to the longitudinal axis and, in
particular, is
welded to the shell. It is preferably provided that the at least one
stiffening ring reaches
around the shell or, as an alternative to this, that the shell reaches around
the stiffening
ring, i.e. runs around on an inner side, facing the shell space, of the shell
or of the two
shell parts.
The pass baffle thus divides the shell space into a first portion, which is
made to
extend along the longitudinal axis, and a second portion, which is made to
extend
parallel thereto and lies opposite to the first shell portion. These two
portions are
connected to one another in a flow-directing manner preferably in the region
of a first
end portion of the shell space. The two portions of the shell space preferably
also
respectively surround an assigned part of the tube space (for example the
tubes of a
tube bundle respectively running in the portion concerned), so that the first
medium,
carried in the two portions, can enter into indirect heat exchange with the
second
medium, carried in the respectively assigned part of the tube space.
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For introducing the first medium into the first portion of the shell space, an
inlet,
for example in the form of a connection piece, is preferably provided on the
shell, at a
second end portion of the shell space that lies opposite from the first end
portion of the
shell space along the longitudinal axis. Furthermore, provided opposite from
that on the
shell, at the second end portion of the shell space, is an outlet, by way of
which the first
medium can be withdrawn from the second portion of the shell space. The first
medium,
introduced into the first portion, can consequently flow along a first
direction to the first
end portion of the shell space and then flow along an opposite second
direction in the
second portion (back) to the outlet for withdrawing the first medium.
In order to be able to deflect the flow of the first medium perpendicularly in
relation to the longitudinal axis, so that for example a cross-counterflow is
possible with
respect to the second medium that is conducted in the tube space, there are
preferably
provided a number of sheet-like cross baffles, which are arranged in the two
portions of
the shell space and correspondingly extend respectively perpendicularly away
from the
pass baffle, and are thereby preferably oriented perpendicularly in relation
to the
longitudinal axis. Neighboring cross baffles are preferably respectively
arranged offset in
relation to one another, so that the first medium flows through the two
portions of the
shell space in a meandering manner. The cross baffles are preferably fixed to
the pass
baffle, to be precise in particular by welding. In principle, the cross
baffles may be
variably distributed or arranged in the shell space (depending on the
application).
The tube space preferably has a tube bundle, arranged in the shell space, or
is
formed by such a tube bundle, the tube bundle having at least a first tube,
running along
the longitudinal axis, and at least a second tube, running along the
longitudinal axis,
which tubes are connected to one another (in one piece) by way of a U-shaped
tube
portion in the region of the first end portion of the shell space. The two
tubes are
anchored at a respective free end, lying opposite from the U-shaped tube
portion, in a
tube sheet of the tube bundle that is made to extend perpendicularly in
relation to the
longitudinal axis, and particularly bounds the shell space and separates it
from a head of
the heat exchanger. The tube bundle preferably has a plurality of such pairs
of first and
second tubes connected by way of a plurality U-shaped tube portions.
The head of the heat exchanger is preferably divided into an inlet chamber and
an outlet chamber, it being possible for the second medium to be introduced
into the
tube space or the tube bundle by way of the inlet chamber and by way of the
tube sheet,
and it being possible for the second medium to be drawn off from the tube
space and out
of the heat exchanger by way of the outlet chamber. An inlet, particularly
provided on
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the shell, is connected to the inlet chamber in a flow-directing manner and is
intended for
introducing the second medium into the inlet chamber. In addition, an outlet,
particularly
provided on the shell, is connected to the outlet chamber in a flow-directing
manner and
is intended for withdrawing the second medium from the outlet chamber.
5
Brief Description of the Drawings
Further details and advantages of the invention are to be explained with the
following description of the Figures of exemplary embodiments on the basis of
the
figures, in which:
Figure 1 shows a schematic sectional view of a heat exchanger according to the
invention;
Figure 2 shows a section through the shell space of the heat exchanger
according
to Figure 1 along the line II-II of Figure 1;
Figure 3 shows a partly sectioned view of the heat exchanger shown in Figures
1
and 2 along the line III-III of Figure 1;
Figure 4 shows a sectional view in the manner of a detail of the heat
exchanger
shown in Figures 1 to 3;
Figure 5 shows a detail of Figure 3 or 4;
Figure 6 shows a detail of Figure 3 or 4 in an alternative embodiment;
Figure 7 shows a sectional view of a heat exchanger according to the
invention,
fitted with a stiffening ring, along the line VII-VII of Figure 1; and
Figure 8 shows a sectional view of a modification of the heat exchanger shown
in
Figure 7 along the line Vill-Vill of Figure 1.
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Figure 1 shows in conjunction with Figures 2 to 8 a heat exchanger 1, with a
pressure-bearing shell 10, which is made to extend along a longitudinal axis
L, which
runs horizontally - with respect to a state of the heat exchanger 1 arranged
as shown.
The shell 10 is preferably given the form of a hollow circular cylinder
(possibly apart from
at the free ends of the heat exchanger 1), so that the longitudinal axis L is
in particular
correspondingly a cylinder axis.
The shell 10 defines a shell space M for receiving a first medium W, which is
particularly water. The shell space M thereby encloses a tube space R of the
heat
exchanger 1, which is designed for receiving a second medium G, which is
particularly a
synthesis gas, so that that second medium G can enter into indirect heat
exchange with
the first medium W, carried in the shell space M.
The tube space R is in this case formed by a tube bundle, which has a
plurality of
first and second tubes 61, 62, which are respectively connected to one another
by way
of a U-shaped tube portion 63 and are respectively anchored by free ends 611
and 621
in a tube sheet 6 of the tube bundle R. In the case of a hollow circular-
cylindrical shell
10, the tube sheet 6 is correspondingly given the form of a circular sheet
(disc-shaped).
The tube sheet 6 bounds the shell space M and separates from it a head K of
the heat
exchanger 1, which is divided into an inlet chamber 301 and an outlet chamber
302 by
means of a wall 312 made to extend along the longitudinal axis L. The head K
of the
heat exchanger 1 is also bounded by a sheet 70, which can be fastened to the
shell 10,
for example by way of a flange, and lies opposite the tube sheet 6 along the
longitudinal
axis L.
The shell 10 of the heat exchanger 1 is mounted on an underlying surface by
way
of connection pieces 50, it being possible for one of the connection pieces 50
to form a
sliding bearing for the shell 10 to compensate for thermally induced stresses.
For directing the first medium W along the longitudinal axis, the shell space
M is
divided along that longitudinal axis L by a sheet-like rectangular pass baffle
20 into a first
portion 201 and a parallel second portion 202, that communicates with the
first portion
201. The two portions 201, 202 are connected to one another in the region of a
first end
portion 2 of the shell space M that lies opposite from the tube sheet 6 along
the
longitudinal axis L. The pass baffle 20 also divides the shell 10 into a first
and a second
shell part 101, 102, which are made to extend along the longitudinal axis L
and
respectively have the form of a half shell. In particular, the two shell parts
101, 102 are
formed mirror-symmetrically in relation to one another, that is to say, for
example, each
forming half of a cylindrical shell.
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The pass baffle 20 thereby also divides the tube bundle R into a first part
and a
second part. The first portion 201 of the shell space M surrounds the first
part of the
tube space or the tube bundle R, and the second portion 202 of the shell space
M
surrounds the second part of the tube space or the tube bundle R. The free
ends 611,
621 of the first and second tubes of the tube bundle R are accommodated here
in the
tube sheet 6 in such a way that the second medium G can be admitted to the
tube
bundle R by way of the tube sheet 6. For this purpose, the second medium G can
be fed
by way of an inlet 310, which is provided on the head K and opens out into the
inlet
chamber 301 (hot side of the heat exchanger 1), into the inlet chamber 301 and
from
there into the first tubes 61 of the tube bundle R (for example at about 300 C
in the case
of a synthesis gas G). The second medium G then flows along the longitudinal
axis L of
the heat exchanger 1 towards the first end portion 2 of the shell space M,
where the first
tubes 61 go over by way of the respectively assigned U-shaped tube portions 63
into the
second tubes 62 of the tube bundle R. The second medium G is then returned
through
the second tubes 62 to the tube sheet 6 and enters the outlet chamber 302,
from which
the second medium G can be withdrawn from the heat exchanger 1 by way of an
outlet
311 (hot side, synthesis gas G at about 200 C).
The first medium W is thus carried in particular in cross-counterflow in
relation to
the second medium G. Provided for this purpose in the region of the tube sheet
6, at a
second end portion 3 of the shell space M that lies opposite from the first
end portion 2
of the shell space M, is an inlet 210 (cold side of the heat exchanger 1). By
way of inlet
210 the first medium W (feed water at for example 100 C) can be introduced
into the
shell space M, so that it flows along a direction E, heading towards the first
end portion
2, to that first end portion 2 in the first portion 201 of the shell space M,
and then flows
back in the second portion 202 along a direction E', opposite in comparison
with the first
direction E, to the second end portion 3 of the shell space M. Provided there
on the shell
10, adjacent to the tube sheet 6 (opposite the inlet 210) is an outlet 211
(cold side of the
heat exchanger 1), by way of which the first medium W can be withdrawn from
the shell
space M (for example said feed water at about 250 C).
In order to be able also to conduct (divert) the first medium W in the shell
space
M transversely in relation to the longitudinal axis L, and correspondingly
bring about a
meandering flow of the first medium W in the first and second portions 201,
202 of the
shell space M, there preferably extend perpendicularly away from the pass
baffle 20 a
plurality of cross baffles 40, which respectively connect the pass baffle 20
to an opposite
inner side of the shell 10.
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The cross baffles 40 are in this case particularly arranged offset in relation
to one
another transversely in relation to the longitudinal axis L according to
Figure 2, so that
passages are formed between the cross baffles 40 and the inner side of the
enclosing
shell 10, thereby forcing the first medium W to flow not only along the
longitudinal axis L
but at the same time also back and forth transversely in relation to the
longitudinal axis
L, as is indicated in Figure 2 by the arrows (cf. also Figures 3 and 4).
The connection between the pass baffle 20 and the first and second shell parts
101, 102 is specifically formed in particular in the way corresponding to
Figures 5 and 6.
Accordingly, the two shell parts 101, 102, respectively, each have a first end
face
103, 104, made to extend along the longitudinal axis L, and a second end face
(not
shown in Figures 5 and 6; see 105, 106, respectively, in Figures 7-8). The
first end face
(103, 104) is in this case brought to lie against a respectively facing first
or second side
21 a, 21 b of a first outer peripheral region 21 of the pass baffle 20 made to
extend along
the longitudinal axis L, those two sides 21 a, 21b facing away from one
another. The two
second end faces 105, 106 correspondingly, lie on both sides of a second outer
peripheral region 22 (not shown in Figures 5 and 6) of the pass baffle 20 on a
first and
second side, respectively, of that second peripheral region 22, which sides in
turn face
away from one another (cf. also Figures 7 and 8). The second peripheral region
22 of
the pass baffle 20 runs parallel to the first peripheral region 21. The pass
baffle 20 is
consequently arranged transversely in relation to the longitudinal axis L
between the two
shell parts 101, 102.
For forming a sealed connection between the pass baffle 20 and the two shell
parts 101, 102 along the longitudinal axis L, the first and second end faces
103, 104 and
105, 106, respectively, are then welded to the respectively assigned side 21
a, 21 b of the
respective peripheral region 21, 22, so that a first, second, third and fourth
weld seam
31-34 result (cf. Figures 7 and 8). These four weld seams are respectively
formed
continuously in a direction oriented perpendicularly in relation to the
longitudinal axis L.
Hereafter, only the first and second weld seams 31, 32 according to Figures 5
and 6 are
described. The third and fourth weld seams 33, 34 are of an analogous form
(cf. Figures
7 and 8).
In the present case, "continuously" with respect to the weld seams means that
the first and second end faces 103-106 are connected to the first and second
peripheral
regions 21, 22, respectively, particularly over their full surface area by way
of the
assigned weld seams 31-34, so that a stable, sealed connection of the shell
parts 101,
102, that can absorb and withstand the pressure exerted on the shell parts
101, 102 by
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9
the first medium W conducted in the shell space M, is ensured all the way
along the
longitudinal axis L. Correspondingly, the first and second weld seams 31, 32,
respectively, have an outwardly facing outer side 31a, 32a, which goes over
into an
outer side 101 a, 102a of the assigned shell part 101 and 102, respectively.
In the same
way, the two weld seams 31, 32 each have an inner side 31 b, 32b, which goes
over into
a respectively assigned inner side 101b, 102b of the corresponding shell part
101, 102
and into an adjacent first side 20a and an adjacent second side 20b of the
pass baffle
20.
According to Figure 5, the first and second weld seams 31, 32 narrow in cross
section towards the shell space M, a step particularly being formed,
respectively on the
inner side 101b, 102b of the assigned shell part 101, 102, so that the weld
seams 31, 32
reach behind the respectively assigned inner side 101b and 102b of the shell
part 101,
102 concerned. Other cross-sectional forms are also conceivable.
Figure 6 shows an alternative embodiment, in which, as a difference from
Figure
5, the pass baffle 20 has a constant thickness in the region of the first and
second
peripheral regions 21, 22. By contrast, the first and second peripheral
regions 21, 22
according to Figure 5 are narrowed in the region of the weld seams 31, 32
respectively
towards an outer space A surrounding the heat exchanger 11. This allows the
effective
connecting area between the pass baffle 20 on the one hand and the shell parts
101,
102 on the other hand to be increased.
Finally, as shown in Figures 7 and 8, the heat exchanger 1 may additionally
have
stiffening rings 80 for the shell 10.
According to Figures 7, it is provided that such stiffening rings 80 reach
around
the shell 10 transversely in relation to the longitudinal axis L, that is to
say run around
from the outer space A. For stiffening the shell 10, the stiffening ring or
rings 80 are in
this case preferably welded around the periphery or at discrete points to the
shell 10 or
the shell parts. The stiffening rings 80 can in this case absorb the load
exerted on the
shell 10 from the shell space M and support the weld seams 31 to 34.
As an alternative to this, according to Figure 8 there is the possibility that
the
stiffening rings 80 run around the inside of the shell 10 transversely in
relation to the
longitudinal axis L and are welded to it around the periphery or at discrete
points. In this
case, corresponding clearances may be provided on the pass baffle 20, through
which
the stiffening rings 80 are led. Furthermore, according to Figure 8, in a
cross-sectional
plane running perpendicularly in relation to the longitudinal axis, weld seams
31, 34 may
CA 02779323 2012-06-06
extend as far as the stiffening rings 80 and correspondingly connect them to
the shell 10
and/or pass baffle 20.
In comparison with the known technical teaching, throughputs in the range of
particularly 80-100 m3/h can be achieved with the solution according to the
invention, for
5 example, in a synthesis gas installation. The present connection between the
pass baffle
and the shell 10 leads to increased reliability of the process and ensures a
more
effective heat exchange between the tube side and the shell side of the heat
exchanger
1.
Apart from synthesis gas installations, the heat exchanger 1 according to the
10 invention may also be used in refineries or power generating plants.
Specifically in the
refinery area, a low risk of bypassing flows is desired. Other industries in
the heat
exchanger area may of course similarly use the invention.
The preceding examples can be repeated with similar success by substituting
the
generically or specifically described reactants and/or operating conditions of
this
invention for those used in the preceding examples.
The entire disclosure[s] of all applications, patents and publications, cited
herein
and of corresponding German Application No. 10 2011 103 635.4 filed June 8,
2011, are
incorporated by reference herein.
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List of designations
1 Heat exchanger
2 First end portion
3 Second end portion
6 Tube sheet
Shell
Pass baffle
20a First side
20b Second side
21 First peripheral region
21a First side
21b Second side
22 Second peripheral region
22a First side
22b Second side
31 First weld seam
31a Outer side
31b Inner side
32 Second weld seam
32a Outer side
32b Inner side
33 Third weld seam
34 Fourth weld seam
40 Cross baffles
50 Connection pieces
61 First tube
62 Second tube
63 U-shaped end portion
70 Sheet
80 Stiffening ring
101 First shell part
102 Second shell part
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201 First portion
202 Second portion
210 Inlet
211 Outlet
301 Inlet chamber
302 Outlet chamber
310 Inlet
311 Outlet
312 Wall
611 Free end
621 Free end
A Outer space
E First direction
E' Second direction
G Second medium
K Head
L Longitudinal axis
M Shell space
R Tube space, tube bundle
W First medium
