JP2764174B2 - Falling liquid film evaporator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention utilizes the latent heat of vaporization by evaporating at least a part of the liquid to be treated while flowing the liquid to be treated in a film form along the peripheral surface of an evaporating tube. The present invention relates to a falling liquid film type evaporator applied as a heat exchanger or a liquid concentrator.

2. Description of the Related Art Conventionally, liquid film evaporators, especially falling film evaporators, have been widely used because of their relatively large processing capacity, simple structure, and easy control. When used as a heat exchanger, the heat pump temperature coefficient can be improved because the heat exchange temperature difference can be reduced by reducing the thermal resistance due to thinning and promoting heat and mass transfer due to interface disturbance. preferable.

However, the device requires a liquid circulation pump for re-directing the refrigerant that has remained in the lower part of the device to the upper end side of the evaporator tube without being completely evaporated by heat exchange on the peripheral surface of the evaporator tube. The more the power of the liquid circulation pump becomes, the more the efficiency of the whole system may be reduced.

[Problem to be Solved by the Invention] For this reason, in general, the liquid supply flow rate to the evaporating tube is reduced to minimize the liquid stagnation after flowing down the evaporating tube. In this case, the uniform distribution of liquid to each evaporator tube and the formation of a stable liquid film are hindered. As a result, a dry surface is generated on a part of the evaporator tube peripheral surface, and the heat transfer performance is reduced. There are cases.

For example, as a method of distributing a liquid when a liquid film is formed on the outer surface of a vertical evaporating tube, a slit type distributing body having a slit space provided around the evaporating tube, or a nozzle for ejecting liquid to the evaporating tube peripheral surface by a nozzle Although there is a slit type distributor, the slit type distributor requires a considerably small gap between the evaporator and the evaporator to enable low flow rate supply. It is difficult to form a stable and uniform liquid film in the circumferential direction due to variations in assembly accuracy. In the case of a nozzle-type distributor, liquid distribution in each of the evaporating tube groups can be performed relatively uniformly even in a low flow rate region. However, the distribution of liquid in the circumferential direction of the pipe is biased due to the effect of the nozzle jet. If the number of nozzles is increased in order to avoid this, the nozzle diameter must be reduced accordingly, so that the nozzle processing accuracy becomes a problem similarly to the slit type.

Therefore, it is difficult to form a stable liquid film when the flow rate of the liquid to be treated is reduced in any of the above-described methods. Particularly, in the case of the evaporator, the liquid film becomes thinner as it flows down the evaporating tube. The liquid film is likely to break near the lower part of the pipe, so in a normal evaporator, the ratio of the liquid supply amount to the evaporation amount is increased to prevent the liquid film from breaking. The excess refrigerant accumulates in the lower part of the evaporator, and the power of the liquid circulation pump for circulating the refrigerant is inevitably increased, thereby reducing the efficiency of the entire system.

For this reason, a multi-stage device in which the evaporating tube is divided into a plurality of evaporating tubes without a single-stage structure and a liquid supply mechanism is provided therebetween (Japanese Patent Application Laid-Open No. 62-136201) has been developed. Since it is impossible to flow water or the like as a heat source into the inside, it is possible to apply a so-called inner-tube type falling liquid film type evaporator in which steam or the like as a heat source is brought into contact with the outer peripheral side. However, application to a device for flowing a liquid to be treated in a film form along the outer peripheral surface of an evaporation tube as in the present invention is impossible.

In view of the drawbacks of the prior art, the present invention provides a flow-down solution capable of forming a stable liquid film over the entire surface of the evaporation pipe even when the flow rate of the liquid to be processed supplied to the evaporation pipe is reduced. An object of the present invention is to provide a film-type evaporator.

Another object of the present invention is to easily form a multi-stage structure in an apparatus for flowing a liquid to be treated in a film form along the outer peripheral surface of an evaporating tube, thereby preventing breakage of a liquid film in the middle of flowing down the evaporating tube. It is an object of the present invention to provide a falling liquid film type evaporator which can be used.

"Means for Solving the Problems" The present invention is to effectively combine the nozzle type and slit type distributors to achieve the above technical problem smoothly, and FIG. As shown in FIG. 2, a plurality of evaporating tubes 10 are provided, and the evaporating tubes 10 are evaporating tubes 10 having a large number of longitudinal grooves 10a formed on the outer peripheral surface. A plurality of distributing means for distributing the processing liquid 11 to the vicinity of the outer periphery of each of the evaporating tubes 10 on the upper surface of a second distributing body 13 which will be described below and functioning as a receiving tray, preferably a number corresponding to the evaporating tubes Distribution means 121
A first distributor 12 having a nozzle (for example, a nozzle), and the liquid to be treated 11 distributed by the first distributor 12 are supplied to the evaporating pipes via dispersing means 131 provided around each of the evaporating pipes 10. And a second distributor 13 for flowing the liquid to be treated 11 in a film form along the outer peripheral surface of the evaporating tube 10 while dispersing in the circumferential direction.

Preferably, the first distributor 12 is a nozzle-type tube plate 12 for spraying liquid onto the second distributor 13 by a nozzle 121, and the second distributor 13 is provided around the outer periphery of the evaporation tube 10. Is provided as a slit-type tube sheet provided with a slit space 131, but is not necessarily limited thereto.

Incidentally, the dispersing means may be constituted by, for example, only the slit space 131 provided on the outer periphery of the evaporating tube 10;
The above operation can be achieved more smoothly by forming a circular concave portion 132 around the outside of the device.

A) As described above, in the present invention, the advantages of each of the nozzle type and the slit type are exclusively used, and the flow rate of the liquid to be treated 11 is first regulated by the nozzle type tube sheet 12 as described above. After being distributed to each evaporating tube 10, the liquid to be treated 11 is configured to be dispersed in the circumferential direction of the evaporating tube 10 by the slit-type tube plate 13. This also enables uniform liquid distribution and liquid film formation.

In other words, the present invention can achieve the above-mentioned effect smoothly even when the flow rate is reduced due to the adoption of the two-stage distribution structure, and in particular, in the present invention, since the nozzle-type tube sheet 12 is arranged on the upstream side, Thus, the advantages of the two distributors 12, 13 can be effectively brought out.

That is, the nozzle jet from the nozzle type tube sheet 12 is not used for adhering the liquid to be treated 11 to the evaporating pipe 10 as in the prior art, but is jetted to the second distribution body 13 functioning as a receiving pan and a predetermined amount is jetted. Since the purpose is to supply, there is no need to increase the number of nozzles, and one nozzle 121 per evaporating tube 10 is sufficient, so that the nozzle diameter can be increased, and as a result, processing becomes easier. No worries about clogging.

In addition, since the nozzle 121 only needs to be sprayed onto the slit-type tube sheet 13 functioning as a receiving pan, it is not necessary to set an inclination angle, and the nozzle 121 can be formed perpendicular to the tube sheet 13. Processing accuracy becomes loose.

In addition, since the liquid to be treated 11 is not supplied excessively to the slit-type tube sheet 13 serving as a receiving pan, the gap accuracy between the evaporating tube 10 and the slit 131 does not have to be strictly set. It is easy to form a stable and uniform liquid film in the circumferential direction, whereby the above-mentioned effect can be achieved smoothly.

In this case, in the preferred embodiment of the present invention, since the annular groove 133 is provided on the upper surface side of the tube sheet 13 so as to surround the periphery of the slit 131, the liquid to be treated 11 ejected from the nozzle 121 is surrounded by the tube. It can be smoothly expanded in the direction, and the above effect is further improved.

Further, by providing the annular groove 134 also on the lower surface side of the tube sheet 13, it serves to prevent uneven distribution of the liquid to be treated 11 attached to the evaporating tube 10 from the slit 131 and to spread it in the circumferential direction of the tube. A state in which the liquid does not adhere to a part is prevented, and the formation of a stable and uniform liquid film in the circumferential direction is further facilitated.

B, By the above method, it is possible to form a liquid film near the evaporating tube 10 directly below the slit tube plate 13, but the liquid film becomes thinner as it flows down the tube due to evaporation, In particular, since the liquid film is likely to be broken at a low flow rate, it is necessary to use the evaporating tube 10 having a structure such that the liquid film formed immediately below the slit tube plate 13 is maintained over the entire length of the tube.

Therefore, in the present invention, since the evaporating tube 10 (hereinafter referred to as a flute tube) having a large number of vertical grooves 10a formed on the outer peripheral surface is used, liquid distribution is performed just below the slit-type tube sheet 13 according to the above-mentioned constitutional requirements. Meanwhile, by flowing the liquid through all the vertical grooves 10a, it is possible to maintain the state up to a considerably low flow rate region over the entire length of the pipe.

In such a case, the liquid film is not uniform in the pipe circumferential direction,
Although it is thicker at the portion of 10a and thinner at the ridge, a dry surface hardly occurs. Also, even if a dry surface is formed in one vertical groove 10a, it does not affect the surrounding vertical grooves 10a, so that the dry surface does not spread or form some streak flow.

C, When the evaporating tube 10 is formed of a bare tube, the liquid film is disturbed when the tube sheets 12 ', 13', and 14 are provided in the middle of the tube 10 due to the structure, which is not preferable. When used in a low flow rate region using the flute pipe, the tube sheet 1 as described above is used.
Even when 2 'and 13'14 are attached, the liquid film is not disturbed.

In addition, since the tube sheets 12 ', 13', and 14 also function as intermediate support plates, it is possible to prevent the evaporating tube 10 from swaying and bending, and to provide the one or more tube sheets 12 ', 13', 14 Are arranged in a multi-stage manner so that the liquid to be treated 11 can be supplied to each of the intermediate distributors 12 ', 13', and 14, thereby successively replenishing the thinned liquid film accompanying the evaporation. I can do it,
A liquid film formed stably and uniformly is maintained over the entire length of the tube, and breakage of the liquid film near the lower end of the tube 10 can be prevented.

D, Since the peripheral surface of the evaporating tube 10 is still dry at the initial stage of the startup when the liquid to be treated 11 is supplied, the liquid film is formed by temporarily increasing the liquid supply flow rate. It is necessary to make it easy.

Therefore, in a preferred embodiment of the present invention, the liquid pipe 60 leading from the processing liquid pump 6 to the evaporator 1 is branched to form the slit type pipe sheet together with the nozzle type pipe sheet 12.
The liquid to be treated 11 can be supplied also on the upper surface 13, so that at the time of start-up, the slit-type tube plate together with the nozzle-type tube plate 12 is provided.
The flow rate can be easily increased by feeding the liquid to be treated 11 onto the surface 13, and the above disadvantage can be solved.

Hereinafter, preferred embodiments of the present invention will be illustratively described in detail with reference to the accompanying drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

FIG. 4 shows a falling film evaporator 1 according to an embodiment of the present invention.
Shows a heat pump system in which a screw compressor 3, a condenser 4, a liquid separator / refrigerant tank 5, and an evaporator 1 connected to a motor 2 are provided in a circulation path of the refrigerant as is known. The refrigerant 11 compressed by the compressor 3 is condensed and liquefied by the condenser 4, temporarily stored in the refrigerant tank 5, and then introduced into the evaporator 1 by the refrigerant liquid circulating pump 6. Evaporation tube 10 vertically set inside
While the refrigerant liquid is flowing in a film shape along the outer peripheral surface, the refrigerant liquid is heated and evaporated by the water flowing through the inside thereof, and the vaporized refrigerant is sucked into the compressor 3 again through the liquid separator / refrigerant tank 5. On the other hand, the refrigerant liquid which has not been evaporated in the evaporator 1 and the refrigerant liquid separated by the liquid separator 5a is stored in the refrigerant tank 5 again, and this cycle is repeated.

Next, the internal configuration of the evaporator 1 will be described in detail.

The evaporator 1 is composed of a vertical large-diameter cylindrical container 20 having water outlets 21 and inlets 22 opened at both upper and lower ends, and the upper and lower end plates of the internal space are partitioned by partition plates 23, 24 to form water retention chambers 25, 24. 26 and a central space 1 sandwiched between the partition plates 23 and 24.
In 9, a pair of tube sheets 12-13, 12'-13 'consisting of a nozzle-type tube sheet 12 and a slit-type tube sheet 13 are arranged at predetermined intervals vertically in multiple stages and divided into a plurality of sections. I do.

Further, a plurality of evaporating tubes 10 are penetrated into the central space 19 so as to penetrate the divided sections, and both ends thereof are opened to the water retention chambers 25 and 26.

On the other hand, the discharge pipe 60 from the liquid circulation pump 6 has its tip side branched into four, and these branch pipes 61 to 64 are respectively formed on the nozzle type tube sheet 12 and the slit type tube sheet 13 via the on-off valve 65. To open. A refrigerant gas return pipe 51 is provided between the space below the slit tube plate 13 and a position immediately below the liquid separator 5a of the refrigerant tank 5, and a refrigerant is provided between the lower end of the central space 19 near the lower partition plate and the bottom of the refrigerant tank 5. Liquid return pipes 52 are connected respectively.

Next, the structures of the evaporating tube 10 and the tube plates 12 ', 13', 14 will be described in detail with reference to FIGS.

The evaporating tube 10 extends along the axial direction of a metal tube with good heat conductivity,
It is formed of a flute pipe having a number of vertical grooves 10a formed evenly on the inner and outer peripheral surfaces.

The nozzle-type tube sheet 12 is formed so as to be able to fit tightly around the outer periphery of the evaporating tube 10 and a nozzle 121 formed by vertically drilling a through hole near the evaporating tube 10.
Slit tube sheet located below the refrigerant that has accumulated on it
It is configured to be able to jet onto the 13 circular recesses 132. The slit tube plate 13 opens a through hole slightly larger than the outer diameter of the evaporating tube 10, forms a ring-shaped slit space 131 having a small gap width with the peripheral surface of the evaporating tube 10, and forms the slit space 1.
A circular recess 132 is formed around the outer periphery of the nozzle 31 so that the refrigerant injected from the nozzle 121 can be stored therein. On the upper and lower surfaces of the circular recess 132, annular grooves 133 and 134 having a semicircular cross section are formed to perform the above-described operation.

Such a pair of tube sheets 12 'and 13' may be arranged at a predetermined gap as shown in FIG. 1 and at a central position thereunder, or as shown in FIG. The intermediate tube sheet 14 may be provided instead of the pair of tube sheets 12 ', 13'.

Next, the operation based on this embodiment will be briefly described because it has already been described in detail in the section of the operation of the present invention.
The liquid circulating pump 6 is driven while flowing into the nozzle 10 to supply the refrigerant 11 to each of the nozzle type tube plate 12 and the slit type tube plate 13 to temporarily increase the liquid supply flow rate. A liquid film is formed uniformly on 10 circumferential surfaces.

After the formation of the liquid film, the supply of the refrigerant 11 from the slit type tube sheet 13 is stopped, and the refrigerant 11 is supplied only from the nozzle type tube sheet 12.
By supplying the refrigerant liquid, the refrigerant liquid 11 can be distributed to the circular concave portion 132 of the slit-type tube plate 13 surrounded around each of the evaporating tubes 10 while controlling the flow rate of the refrigerant liquid from the nozzle 121. Is distributed in the circumferential direction of the evaporating tube 10, a liquid film can be formed on the circumferential surface side of the evaporating tube 10 through the slit gap 131. The flow rate regulation of the refrigerant liquid 11 can be easily controlled by changing or selecting the refrigerant liquid height H on the slit 121 and the diameter of the nozzle 121.

Then, in this embodiment, the same tube sheet 12 ′, 1
3 ′, a group or a multi-stage structure with an intermediate tube plate 14 having a slit gap 131 and a structure in which a coolant liquid can be supplied to each of the intermediate tube plates 12 ′, 13 ′, 14 The film liquid thinned due to the evaporation can be successively replenished together with the stagnation of the unevaporated refrigerant, and a stable and uniform liquid film can be maintained over the entire length of the pipe 10.

[Effects] As described above, according to the present invention, by combining a two-stage distribution structure and a flute tube with a vertical groove, even when the flow rate is reduced, uniform liquid distribution and liquid film formation can be achieved. Since no extra refrigerant liquid is supplied, the power of the liquid circulation pump can be reduced and the heat transfer performance can be improved.

In addition, the use of the evaporating tube with the vertical groove increases the evaporating surface area and accordingly reduces the number of evaporating tubes to be installed, thereby saving space.

In particular, the present invention can be easily formed into a multi-stage structure even in a device in which a refrigerant liquid flows in a film shape along the outer peripheral surface of an evaporating tube by using the evaporating tube having a vertical groove in a low flow rate region. As a result, not only breakage of the liquid film in the middle of flowing down the evaporating tube can be prevented, but also swinging or bending of the evaporating tube can be prevented.

In addition, the multi-stage structure using the liquid distribution mechanism composed of the first distribution body and the second distribution body is a form in which the liquid is held and redistributed at each distribution mechanism stage, so that the liquid distribution biased at the upper part is performed. Even if this is done, effects such as uniformization in the next stage are derived.

 And so on.

[Brief description of the drawings]

1 to 4 show an evaporating apparatus according to an embodiment of the present invention. FIG. 1 is an overall view, FIG. 2 is a detailed view of an internal main part, and FIG. 3 is a cross-sectional view of FIG. FIG. 4 is an overall schematic view of a heat pump system using the evaporator.

Claims (6)

(57) [Claims] 1. A falling liquid film type wherein a liquid to be treated is allowed to evaporate at least a part of the liquid to be treated while flowing the liquid to be treated in the form of a film along the outer peripheral surface of an evaporating pipe vertically provided in an evaporation container. In the evaporator, a plurality of evaporator tubes having a large number of vertical grooves formed on the outer peripheral surface thereof, and a second distributor, which is disposed below and serves as a receiving pan, for the liquid to be treated introduced into the evaporator. A first distributor having a plurality of distributing means including nozzles or slits respectively distributing to the vicinity of the outer periphery of each of the evaporating tubes on the upper surface, and a liquid to be treated distributed by the first distributor, A second distributor composed of a slit or a nozzle for flowing the liquid to be treated in a film form along the outer peripheral surface of the evaporator tube while dispersing in the circumferential direction of the evaporator tube via a dispersing means provided around the outer periphery of the evaporator tube. A falling liquid film type evaporator characterized in that: 2. The falling liquid film evaporator according to claim 1, wherein a liquid pipe leading from the liquid pump to be processed to the evaporator is branched, and the liquid pipe is formed on the first distributor and on the second distributor. A falling liquid film type evaporating apparatus characterized in that the liquid to be treated can be supplied to the apparatus. 3. The falling film evaporator according to claim 1, wherein the first and second evaporating pipes are provided in the evaporator.
A falling liquid film type evaporator, wherein a plurality of distributor units each comprising a distributor are arranged vertically. 4. The first distributor is a nozzle-type tube plate for spraying liquid onto a second distributor by a nozzle, and the second distributor is provided with a slit having a slit space around an evaporation tube. The falling liquid film type evaporator according to claim 1, 2) or 3), which is a tube tube. 5. A falling liquid film type in which at least a part of the liquid to be treated is allowed to evaporate while flowing the liquid to be treated in the form of a film along the outer peripheral surface of an evaporating pipe vertically provided in an evaporating vessel. In the evaporator, a plurality of evaporator tubes having a large number of vertical grooves formed on the outer peripheral surface, a slit tube plate having a slit space provided around each of the evaporator tubes, and a nozzle above the slit tube plate A nozzle-type tube sheet for performing liquid injection on the slit-type tube sheet is provided, and the liquid to be treated introduced into the evaporator is supplied onto the nozzle-type tube sheet. A falling liquid film type evaporating apparatus characterized in that the liquid is distributed to the vicinity of the outer periphery of each of the evaporating tubes on the upper surface of the slit type tube plate. 6. The falling film evaporator according to claim 4, wherein annular grooves are provided on both upper and lower sides of the tube sheet so as to surround the periphery of the slit of the slit tube sheet. Falling film evaporator.