Note: Descriptions are shown in the official language in which they were submitted.
21 81277
WO 95/21009 1 PCT/F195/00046
Evapo,rating apparatus
The invention relates to an evaporating apparatus according to the
5 preamble of claim 1.
The evaporating apparatus according to the invention is used for carry-
ing out an evaporation process, wherein fluid is co"ce"lraled by evapo-
rating part of it, most often under conditions of a pressure below the
10 atmospheric pressure of the environment. The energy required by the
evaporation process is produced by using a pressurizer effective in the
process gas.
According to prevalent prior art, the blade wheel of the pressurizer,
15 usually of a blower, is in the process gas. An electrically driven operat-
ing unit, most usually an electric motor, is mounted as a part of the
pipework outside the evaporating apparatus. The pressurizer and its
operating unit are joined by a shaft penetrating the mantle structure of
the evaporating apparatus. The point of penetration is sealed with a
20 shaft seal. In the known solutions, the bearing is carried out either by
roller means or by slide bearing, wherein oil is used as a lubricating
agent. A problem with the solutions of prior art presently in use is the
fact that it is very difficult to seal the operating shaft, with the risk of
leakage primarily caused by the higher pressure of the environment.
25 Leakage of this sealing will directiy result in a significant reduction of
the efficiency of the evaporating process. Maintenance of the shaft
sealing at short intervals requires stoppage of the evaporating process
even for long periods, thus resulting in high maintenance costs of the
evaporating apparatus. Further, the size of the evaporating apparatus is
30 large according to conventional solutions, thus requiring relatively
sturdy lifting systems in connection with the evaporating apparatus and
a relatively large area of space.
It is an aim of the present invention to eliminate significantly the dis-
35 advantages of prior art presented above and to provide also new,unexpected advantages for improving the evaporation process. In order
to achieve these aims, the evaporating apparatus according to the in-
vention is primarily characterized in that at least one pressurizing unit of
WO 95/21009 2 1 & i 2 7 7 PCT/F195/00046
the evaporating apparatus and at least one operating unit of the same
are integrated as a compact structure which is placed as a whole in the
space limited by the mantle structure. The evaporating apparatus ac-
cording to the invention, particularly the structure of the pressurizing
unit and the operating unit, is very simple and makes it possible to
place the whole unit hermetically inside the evaporating apparatus or
the pipework in direct connection therewith. Cooling and/or lubrication
of the operating unit and its bearings can be carried out using a fluid,
particularly water, present in or supplied to the evaporating system.
Thus the dynamic sealing points required by shafts penetrating the
mantle structure can be eliminated by the evaporating apparatus ac-
cording to the invention. When the operating unit is placed inside the
mantle structure of the evaporating apparatus, its warming-up energy
can be utilized in the evaporating process itself. The bearing can be
carried out by the contact-free principle, wherein particles are not
formed during the use which could possibly spoil the process, thus
contributing to the improvement of the quality of the evaporating
process. It is obvious that the hermetically closed integrated structure of
the evaporating apparatus does not cause noise in the environment.
According to a particularly advantageous embodiment, the evaporating
apparatus of the invention is characterized in that the revolving speed
of the operating unit is chosen in the so-called high-speed range,
wherein it is 2.5 X 104 to 3 x 105 revolutions per minute, advantageously
3 x 104 to 7 x 104 revolutions per minute.
In particular, using an integrated compact structure of the invention by
applying high-speed technology gives the advantage of a small size of
the structure, wherein also the size of the evaporating apparatus is na-
30 turally reduced in reiation to the efficiency of the evaporating process,thus reducing the need in total investments for structures, the spaces
required for them, lifting devices, etc.
Further, a significant advantage of the invention is the fact that the in-
35 tegrated compact structure makes it possible to dampen the pressur-
ized steam produced by the pressurizing unit and thus to saturate the
steam by a simple construction that can be placed in connection with
the integrated structure. It is known that the pressurizing unit produces
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steam in superheated state. It is obvious for a man skilled in the art that
superheated steam requires an increase in the heat-exchanging surface
of a heat exchanger if the steam produced by the pressurizing unit is
supplied to the heat exchanger in superheated state. Using the evapo-
rating apparatus according to the invention, it is possible by simple
measures to moisten the steam advantageously in connection with an
integrated compact structure so that the steam pressurized by the
pressurizing unit is supplied to the heat exchanger substantially as
superheated steam.
Several advantageous embodiments of the evaporating apparatus ac-
cording to the invention are presented in the appended dependent
claims.
In the following description, the evaporating apparatus according to the
invention will be illustrated more closely with reference to the appended
drawings. In the drawings,
Fig. 1 shows schematically the evaporating process of the evapo-
rating apparatus according to the invention as a whole,
Fig. 2 shows a cross-sectional view of the integrated compact
structure, an embodiment thereof, and
5 Fig. 3 shows schematically an embodiment of the evaporating ap-
paratus, wherein the evaporating apparatus comprises two
or several integrated compact structures.
As shown particularly in Fig. 1, the evaporating apparatus for concen-
30 trating a fluid comprises a substantially closed hermetic mantle struc-
ture 1 for carrying out the concentration process in a space limited by
the mantle structure 1. The fluid to be concentrated is led via a pipe-
work 2 to an inlet 3, through which the fluid to be concentrated, pene-
trating the mantle structure 1, is conveyed from the upper part of the
35 mantle structure 1 to the evaporating side, i.e. to the first side 5, of a
heat exchanger 4. The steam evaporated from the fluid to be concen-
trated is sucked from the lower part of the mantle structure through a
suction opening 8 of a vertical channel 7 comprising an integrated
WO95/21009 2 1 8 ~ 2 7 / 4 PCT/~195/00046
structure 6 to a first guide vane 9 of the integrated structure and further
to a blade wheel 10, after which the pressurized steam, which has a
higher thermal capacity and thus also a higher temperature, is led
through a second guide vane 11 to a ring channel 12. The latter end in
5 the flow direction of the integrated structure 6 comprises means 13 for
feeding water to be mixed with the steam phase to be supplied to the
condensing side, i.e. the second side 14, of the heat exchange surface.
In the lower part of the mantle structure 1, a first outlet 15 is provided
for discharging the concentrated fluid part, i.e. the concenl,ale, from the
10 space limited by the mantle structure 1. The fluid to be concentrated
flows through the heat exchanger4 on the first side5 of the heat
exchange surface to the lower part 1a of the mantle structure, wherein
the steam phase developed therein is conveyed in a manner described
above to the channel 7 (arrows N in Fig. 1). In a corresponding manner,
15 the mantle structure 1 comprises a receiving part 1a undemeath the
heat exchanger and a second outlet 16 in connection with the receiving
part 1 a for discharging the water separated from the fluid to be concen-
trated, i.e. the condensing water, from the space limited by the mantle
structure 1, wherein also this flow runs through the heat exchanger on
20 the second side 14 of the heat exchange surface. For improving the effi-
ciency of the evaporating process, both the concentrate and the con-
densing water are led through the heat exchangers 17 and 18 to further
processing, wherein the fluid to be concentrated is supplied via the
pipework 2 through said heat exchangers 17 and 18 inside the mantle
25 structure 1. In this manner the thermal capacity of the above-mentioned
fractions produced by the evaporating process is substantially re-
claimed and returned to the evaporating process.
Further, the evaporating apparatus comprises a control unit 19 for con-
30 trolling, in a manner to be disclosed more closely further on, the flow of
water to be directed into the integrated structure, on one hand for cool-
ing the operating unit and on the other hand for adding water to be
mixed with the steam phase. The flow of water is led via the pipe-
work 20, the control unit 19 controlling a valve 21 in the pipework. After
35 the integrated structure6, the channel 7 also comprises a sensor
means coupled with the control unit 19, particularly at least one sensor
means 22 for monitoring the pressure and the temperature.
WO95/21009 2 1 8 1 2 7 7 PCT~5/00046
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With particular reference to Fig. 2, the integrated structure 6 according
to the invention comprises a combination of a pressurizing unit 6a
(blade system 9, 10, 1 1 ) and its operating unit, particularly an electric
motor 6b, the combination being structurally assembled as one com-
5 pact unit. The integrated solid structure is a compact unit placed insidethe pipe section 25 forming the outer wall of the channel 7 so that the
longitudinal axes of the pipe section 25 and the integrated structure 6
are parallel and coaxial, wherein the above-mentioned ring channel 12
is formed between the pipe section 25 and the outer surface of the in-
10 tegrated structure 6 particularly in the part following the pressurizingunit 6a seen in the flow direction (upwards in Fig. 2).
Particularly in the embodiment shown in Fig. 2, the operating unit 6b is
placed in the ring channel, following the pressurizing unit 6a in the flow
15 direction of the steam phase. Particularly the part of the ring channel 12
that follows the pressurizing unit is formed as a diffusor part by expand-
ing the diameter of the pipe section 25 towards the upper end in the
flow direction. It is naturally possible to arrange the order of the
pressurizing unit 6a and its operating unit 6b also reverse in the flow
20 direction, wherein a separate diffusor part can be placed in the structure
in its longitudinal direction following the pressurizing unit. Particularly
for replacing and maintenance operations, the parts 6a, 6b and 25 can
be arranged as an integrated structure, wherein a protruding attach-
ment flange 26 is provided in the upper part of the structure for fixing
25 the structure e.g. in a manner shown in Fig. 1 centrally on the vertical
centre line of the heat exchanger and the mantle structure with a circu-
lar horizontal cross-section so that the central axis of the integrated
compact structure 6a, 6b, 25 joins the vertical central axis of the mantle
structure. The lower part of the channel 7 is thus formed as a solid
30 structure 7a (Fig. 1), wherein the joint between the pipe section 25 and
the lower part 7a of the channel 7 is provided with suitable sealings 27.
The integrated structure 6 shown in Fig. 2 comprises end parts 28
and 29 as well as a shell part 30 in the longitudinal direction of the
35 channel 7 therebetween. The guide vanes 9, 11 are fixed on one hand
to the shell part 30 and on the other hand to the inner surface of the
pipe section 25, and the blade wheel 10 is, in turn, fixed to a longitudi-
nal shaft 31 inside the integrated structure, this shaft forming also the
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WO 95/21009 PCT/FI95/00046
rotor of the electric motor used as the operating unit. A stator part 32 is
provided outside the rotor part 31 of the shaft 31 and inside the
shell 30. Further, the integrated structure comprises at both ends of the
stator part 32 contact-free radial bearings 33 and 34 as well as an axial
5 bearing 35. The required electric inlets can be provided e.g. through the
guide vanes 9 and/or 11. For cooling the operating unit 6b, the operat-
ing unit is provided with a cooling channel system 36, 37, 38. A water
flow is arranged here in a manner described above in connection with
Fig.1, which flow can under special conditions also be a steam flow
10 supplied to the operating unit from other parts of the evaporating
process, e.g. from the lower part of the mantle structure. At least part of
this water flow that is led through the pipework 20 is conveyed to the
ring channel 12 or to its end through a nozle structure 13 which in the
presented embodiment is formed in connection with the latter end 29 of
15 the integrated structure 6. The end 29 is formed as a rotable disk-like
structure, wherein its inner part is provided with a container part or a
ring cavity 39 into which the water flow runs from the cooling channel
system 36, 37, 38. The end 29 is fixed to the shaft 31 and sealed in re-
lation to the end 40 of the outer part 30a of the shell.
The cooling channel system comprises a first part 36 forming an ex-
tension to the pipework 20 and running through the second guide
vane 11 to the shell part30. The shell part of the operating unit6a
comprises two parts, wherein the second part 37, e.g. a ring-like space,
25 of the cooling channel system is formed in the longitudinal direction of
the integrated structure 6 between the outer30a and inner30b part.
The first part 36 of the channel system may comprise several sections,
wherein the supply of the water and/or steam flow is carried out in the
direction of the periphery from two or several points to the second
30 part 37 in connection with the integrated structure 6. The cooling chan-
nel system is used for cooling the electric motor operating as the supply
unit. The third part of the cooling channel system is formed of a control
part 38, from which the water or steam flow is led to the above-men-
tioned ring cavity 39 and further by centrifugal force to the nozles 13.
Figure 3 shows an alternative embodiment of the invention, wherein the
mantle structure is connected with a circulating pipe 41, said circulating
pipe being substantially arranged to form an hermetic unit with the
WO95/21009 2 1 8 ~ 2 7 7 PCT~5/00046
mantle structure. The direction of the steam flow is indicated by ar-
rows KS in Fig. 3. In other respects, the mantle structure corresponds in
applicable manner to the structure presented previously in Fig. 1, and
being thus obvious to a man skilled in the art, it will not be illustrated in
more detail in this context. It is substantial to the general construction of
Fig. 3 that the integrated compact structure is placed in the circulating
pipe 41. In this connection, the integrated compact structure comprises
two parallelly placed independent units 6', 6" fixed to the connecting
pipe by means of a flange structure 42. The integrated compact struc-
tures 6' and 6" can be easily demounted and replaced. In structural
terms, the units may correspond to that presented previously in con-
nection with Fig. 2.
It is obvious that the integrated compact structure can be carried out by
the radial principle instead of the pressurizing unit operating on the
axial principle as shown in the figures. The pressurizing unit can also
comprise several stages.
The revolving speed of the shaft 31 of the operating unit is chosed from
the so-called high-speed range, wherein it is 2.5 X 104 to 3 x 105 revo-
lutions per minute, advantageously 3 x 104 to 7 x 104 revolutions per
minute. It is obvious that several means for carrying out the water addi-
tion can be placed in series in connection with the integrated compact
structure, wherein the energy required by the jets can be arranged also
in other ways.
