WO1995021009A1

WO1995021009A1 - Evaporating apparatus

Info

Publication number: WO1995021009A1
Application number: PCT/FI1995/000046
Authority: WO
Inventors: Kari SÄILY
Original assignee: High Speed Tech Oy Ltd
Priority date: 1994-02-03
Filing date: 1995-02-03
Publication date: 1995-08-10
Also published as: AU1579095A; MX9603020A; FI95102B; EP0744983A1; FI940495A0; CA2181277A1; JPH09508313A; FI95102C; JP3844252B2

Abstract

Evaporating system for concentrating water comprises a mantle structure (1), inlets and outlets (3, 15, 16), a heat exchanger (4), a pressurizing unit (6b) and its operating unit (6a). The invention is characterized in that the pressurizing unit (6b) and its operating unit (6a), particularly an electric motor, are formed as an integrated compact structure (6) placed as a whole in the space limited by the mantle structure (1).

Description

Evaporating apparatus

The invention relates to an evaporating apparatus according to the preamble of claim 1.

The evaporating apparatus according to the invention is used for carry¬ ing out an evaporation process, wherein fluid is concentrated by evapo¬ rating part of it, most often under conditions of a pressure below the 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, 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 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. Leakage of this sealing will directly 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 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- 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 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- turally reduced in relation 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- 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 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

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- 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 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 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 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 concentrate, from the space limited by the mantle structure 1. The fluid to be concentrated flows through the heat exchanger 4 on the first side 5 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, the mantle structure 1 comprises a receiving part 1a underneath the heat exchanger and a second outlet 16 in connection with the receiving part 1a 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 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 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- 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 the integrated structure 6, 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. 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, 11) and its operating unit, particularly an electric motor 6b, the combination being structurally assembled as one com- pact unit. The integrated solid structure is a compact unit placed inside the 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- tegrated structure 6 particularly in the part following the pressurizing unit 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 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 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 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 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 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 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 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 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 nozzle structure 13 which in the presented embodiment is formed in connection with the latter end 29 of 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 part 30. The shell part of the operating unit 6a comprises two parts, wherein the second part 37, e.g. a ring-like space, of the cooling channel system is formed in the longitudinal direction of the integrated structure 6 between the outer 30a and inner 30b 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 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 nozzles 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 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.

Claims

Claims:

1. Evaporating apparatus for concentrating a fluid particularly by separating at least part of the water contained in the fluid apart from the fluid part thus concentrating, wherein the evaporating apparatus comprises:

a substantially closed mantle structure (1) for carrying out the con¬ centration process within the space limited by the mantle struc- ture (1 ),

an inlet (3) for supplying the fluid to be concentrated into the space limited by the mantle structure (1),

- a first outlet (15) for discharging the concentrated fluid part, i.e. the concentrate, from the space limited by the mantle structure (1),

a second outlet (16) for discharging the water separated from the fluid to be concentrated, i.e. the condensing water, from the space limited by the mantle structure,

a heat exchanger (4) in the space limited by the mantle struc¬ ture (1), the flow of the fluid to be concentrated is arranged on the first side (5) of the heat exhange surface, and the flow of water evaporating from the fluid to be concen¬ trated is arranged on the second side (14) substantially in the steam phase,

- at least one pressurizing unit (6b) in the space limited by the mantle structure (1) in order to increase the thermal capacity of the steam phase to be supplied to the second side (14) of the heat exchange surface, and

- at least one operating unit (6a), particularly at least one electric motor, for said at least one pressurizing unit (6b), characterized in that at least one pressurizing unit (6b) of the evapo¬ rating apparatus and at least one operating unit (6a) of the evaporating unit are integrated as a compact structure which is placed as a whole in the space limited by the mantle structure (1).

2. Evaporating apparatus according to claim 1 , character¬ ized 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 revolu¬ tions per minute, advantageously 3 x 10⁴ to 7 x 10⁴ revolutions per minute.

3. Evaporating apparatus according to claim 1 or 2, character¬ ized in that preferably in connection with the integrated compact structure (1), means (13, 29) are arranged for feeding water to be mixed with the steam phase to be supplied to the second side (14) of the heat exchange surface, particularly for the purpose of adjusting the steam phase to be supplied to the second side of the heat exchange surface into saturated steam.

4. Evaporating apparatus according to any of claims 1 to 3, characterized in that the flow channel of the steam phase to be sup¬ plied to the second side (14) of the heat exchange surface of the heat exchanger at the point of the integrated compact structure (6) is a ring channel (12) and that the pressurizing unit (6b) and the operating unit (6a) are placed one after another in the longitudinal direction of the ring channel (12) substantially centrally in the ring channel (12).

5. Evaporating apparatus . according to any of claims 1 to 4, characterized in that the part of the ring channel (12) that follows the pressurizing unit (6b) is formed as a diffusor part.

6. Evaporating apparatus according to any of claims 1 to 4, characterized in that the operating unit (6a) is placed after the pres¬ surizing unit (7b) in the flow direction of the steam phase in the ring channel.

7. Evaporating apparatus according to any of claims 1 to 6, characterized in that for cooling the operating unit (6a), the operating unit is provided with a cooling channel system (36, 37, 38) provided with a flow of a medium in water and/or steam form and that at least part of the water flowing in the cooling channel system (36, 37, 38) are arranged to be led through the means (13, 29) for feeding water prefer- ably as a steam phase to the second side (14) of the heat exchange surface.

8. Evaporating apparatus according to claim 3 or 7, character¬ ized in that the means (13, 29) for feeding water to be mixed with the steam phase are arranged to be driven by the shaft (31) of the operat¬ ing unit (6a), wherein said means (13, 29) are placed in the integrated compact structure (6) after the pressurizing unit in the flow direction of the steam phase to be supplied to the second side of the heat ex¬ change surface.

9. Evaporating apparatus according to claim 3, 7 or 8, charac¬ terized in that the means for feeding water to be mixed with the steam phase supplied to the second side (14) of the heat exchange surface comprise a disk-like structure (29) which is preferably at least part of the end of the integrated compact structure (6) and which comprises centrally the inner container part (38) of the integrated compact struc¬ ture (6), the container part (38) being in connection with flow openings, such as a nozzle system (13) in connection with the container part (38), wherein the container part (38) is provided with a flow of water through said cooling channel system (36, 37, 38).

10. Evaporating system according to any of claims 1 to 9, char¬ acterized in that the flow channel (7) is provided with at least one sensor means (22) monitoring the state of the steam phase supplied to the second side (14) of the heat exchange surface, the sensor means (22) being connected with a control unit (19) for controlling the means, such as a valve (21), for controlling the amount of water added.

11. Evaporating system according to claim 1 , characterized in that the guide vane system (9, 11) of the pressurizing unit (6b) is fixed to the shell part (30) of the integrated compact structure (6) substan¬ tially to protrude from the frame and to be fixed in the channel and that the blade wheel system (10) of the pressurizing unit is fixed in the shaft (31) of the integrated compact structure (6), to protrude from the shell part (30).