JPH0518618Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is a falling film evaporation system used in ocean temperature difference plants that utilize low temperature differences, such as the difference in temperature between the surface layer and the deep layer of seawater, to generate electricity. Concerning the improvement of utensils.

(Conventional technology) This type of plant uses surface seawater as a high heat source.
Deep seawater is used as a low heat source, and low boiling point media such as chlorofluorocarbons and ammonia are used as working fluids.

The system diagram is shown in FIG. 1 and will be explained in detail. Reference numeral 11 is an evaporator that uses surface seawater as a heating medium, and the steam generated in this evaporator 11 is
It is introduced into the turbine 12 and converted into electrical energy by, for example, rotating a generator 13. The steam that has finished its work in the turbine 12 is led to a condenser 14, where it is condensed by deep sea water. The condensed working fluid passes through the recovery container 15 and is sent to the circulation pump 1.
6 and returned to the evaporator 11, and this cycle is repeated thereafter. Since the turbine bypass valve 17 is opened and closed in response to changes in the load of the generator 13, the amount of evaporation of the working fluid from the evaporator 11 is constant. In addition, the code|symbol 18 has shown the main steam stop valve.

Conventionally, in this type of plant, a plate type, a pool boiling type, a falling film type, etc. have been proposed as the evaporator 11. Generally, these ocean temperature difference power generation plants have low plant efficiency and require a large installation space, so as the turbine output increases, the equipment becomes large and difficult to install on land. In addition, in these ocean temperature difference power generation plants, a slight increase or decrease in pressure loss on the seawater side affects the power transmission end output of the turbine 12, so it is not a good idea to forcefully convey the intake seawater to land. For this reason, offshore installation (floating) type plants are being considered for large-scale plants. In this case, since each of the above-mentioned devices is installed on the purge, it is necessary to have a compact device arrangement, and a falling film evaporator configured vertically is used rather than a general horizontal evaporator.

FIG. 2 shows an example of this type of evaporator. The heating fluid (surface seawater) flows from the seawater inlet 21 to the upper water chamber 2.
2, and flows down inside the heat transfer tubes 24 arranged along the longitudinal direction of the evaporator shell 23. on the other hand,
The fluid to be heated (chlorofluorocarbon, ammonia, etc.) is supplied from the evaporated liquid inlet 25 and stored while maintaining the liquid level height H in the distribution chamber 26a partitioned by the partition plate 26. From here, the fluid to be heated is gradually transferred to heat transfer tube 2.
At this time, the heat exchanger tubes 24
It exchanges heat with the heating fluid passing inside the heat transfer tube 24 while forming a liquid film on the outer surface of the heat exchanger tube 24 , evaporates, and partially turns into steam, which is discharged from the steam outlet 27 . The fluid to be heated that has not been completely evaporated is pressurized by a recirculation pump (not shown), and is again supplied into the vessel together with the fluid to be heated whose pressure has been increased by the circulation pump 16 shown in FIG. Although not shown, the evaporator is equipped with a lower water chamber that receives the heating fluid that has flowed through the heat transfer tubes 24.

FIG. 3 shows the evaporated liquid distribution means used in the evaporator described above. This distribution means has an annular distribution port 30 formed by a distribution pipe 29 supported by a partition plate 28 that partitions a distribution chamber 26. When the liquid having a certain liquid level height H as shown in this figure passes through the distribution port 30 formed between the heat exchanger tubes 24 and 29, the flow rate is restricted and A thin liquid film is formed on the surface.

(Problem that the invention aims to solve) By the way, in order to fully demonstrate heat transfer performance in this type of evaporator, it is necessary to increase the flow rate of the flowing fluid as much as possible to form a uniform and stable liquid film. It is necessary. However, when the flow rate of the fluid is increased, the amount that cannot be evaporated increases, the driving power of the recirculation pump increases, and the power generation output decreases. In other words, from the standpoint of heat transfer performance, the larger the amount of fluid flowing down, the better, but if the amount of fluid flowing down is large, the recirculation flow rate will increase and the power output will decrease. From this point of view, in the evaporator of the ocean temperature difference power generation plant that is put into practical use, a heated fluid of several times the amount of evaporation flows down, but the gap corresponding to this amount of fluid flow is about 0.5 to 1.0 mm. be.
In evaporators for ocean thermal power generation plants that use long heat transfer tubes (approximately 10 m), several distribution chambers are provided in the longitudinal direction of the heat transfer tube, and distribution piping is required for each heat transfer tube in each section. . The conventional distribution chamber 26 shown in FIG. 3 is configured to use a partition plate 28, which is in direct contact with the heat transfer tube 24 in order to ensure a constant fluid flow rate as described above. cannot be matched. Therefore, heat exchanger tube 2
4 and the center of the distribution pipe 29 are difficult to make concentrically, even with advanced manufacturing technology.
Moreover, since the gap is as small as 0.5 to 1.0 mm, a minute eccentricity causes the gap between the distribution ports 30 to be biased, and in an extreme case, the distance between the centers becomes equal to the gap distance, and the heat exchanger tube 24 There may also be direct contact between the outer surface and the inner surface of the distribution pipe 29. In this case, since a uniform and stable falling liquid film is not formed, dry patches (portions not wetted with liquid) may occur on the outer surface of the heat transfer tube 24 or peeling may occur from the liquid film of the heating fluid. Therefore, the evaporator is no longer able to exhibit a predetermined performance, and the amount of steam generated in the evaporator decreases, resulting in a decrease in the power generation output.

The purpose of the present invention is to provide a falling film evaporator that can form a uniform and stable liquid film on the outer surface of the heat transfer tube, which is a component of the heat transfer surface in the falling film evaporator. .

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a cylindrical evaporator shell, an upper water chamber partitioned at the upper part of the evaporator shell, and an upper water chamber. It accommodates a certain section near the upper end of a large number of heat transfer tubes that are connected in series on the lower side and extends from the water chamber to the lower water chamber below, and allows the supplied evaporated liquid to adhere to the outer surface of each heat transfer tube in the form of a film. An annular space is maintained between a distribution chamber having a distribution port through which the liquid flows through the distribution chamber, and each heat transfer tube passing through the distribution chamber is inserted into the distribution chamber, and the flow rate of the evaporated liquid supplied to the heat transfer tubes is adjusted. a distribution collar having a plurality of through holes, the through holes extending across the axis of the distribution collar and tangential to the heat exchanger tubes so that the evaporated liquid is supplied to the outer surface of the heat exchanger tubes as a swirling flow. It is characterized by being formed in the same direction.

(Function) The fluid flowing out as a jet from the through holes of the distribution collar adheres to the outer surface of the heat transfer tube while swirling, and forms a liquid film of uniform thickness on the outer surface.

At this time, since the annular space between the distribution collar and the heat transfer tube is kept uniform over the entire circumference, the distance that the jet flow from the through hole reaches the heat transfer tube is always constant.

This completely eliminates dry patches that occur on the outer surface of the heat exchanger tube.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 4 and 5, which show a distribution means attached to a heat exchanger tube.

In FIG. 4, reference numeral 31 indicates a partition plate in which distribution ports 32 are bored to match the heat exchanger tubes 24. The space above the partition plate 31 is formed as a storage space for the fluid to be heated, as in the conventional case, and constitutes a distribution chamber 26a. The heat exchanger tube 24 passing through the distribution chamber 26a is provided with a distribution collar 35 which is kept concentric with the heat exchanger tube 24 by a center hole 34 fitted with a packing 33. The interior of this distribution collar 35 is an annular space 36 separated from the distribution chamber 26a.
The opening thereof faces downward and communicates with a distribution port 32 having a larger diameter than the annular space 36.

Additionally, as shown in FIG.
is provided with a through hole 37 bored in a direction that crosses its axis and coincides with the tangent line of the heat exchanger tube. In the case of this embodiment, four through holes 37 are formed at equal intervals on the circumference at a certain height from the partition plate 31.

In the embodiment of the present invention having the above configuration, the only path for the fluid flowing down the heat transfer tube 24 is the path from the through hole 37 to the outer surface of the heat transfer tube 24 via the annular space 36, and the direction of the through hole 37 is distributed. Since it is oriented in a direction that crosses the axis of the collar 35 and coincides with a tangent to the heat exchanger tube 24, the fluid flows to the outer surface of the heat exchanger tube 24 while swirling. By appropriately determining the number and diameter of the through holes 37, the above-mentioned function becomes even more remarkable.

Further, the elasticity of the packing 33 attached to the center hole 34 makes it easy to align the center of the distribution collar 35 with the center of the heat transfer tube 24. As a result, both centers coincide, so the annular space 36
is not biased to one side.

That is, the fluid having a certain height H forms a jet from the four through holes 37 and attaches to the outer surface of the heat exchanger tube 24 while swirling, thereby forming a liquid film with a uniform thickness on the outer surface of the heat exchanger tube 24. Form. At this time, distribution color 3
Since the annular space 36 between the heat exchanger tube 24 and the heat exchanger tube 24 is kept uniform over the entire circumference, the distance that the jet stream reaches from the through hole 37 to the heat exchanger tube 24 is always constant.

Furthermore, in the conventional evaporator shown in FIG. 3, when fixing the distribution pipe 29 to the partition plate 28,
In order to ensure the uniformity of the gap between the distribution ports 30, it has been necessary to measure the gap using a feeler gauge or the like and adjust the gap, but according to this embodiment, the distribution collar 35 is attached to the heat transfer tube 24. Afterwards, simply by fixing the distribution collar 35 to the partition plate 31, the annular space 36 can be easily made into a uniform gap.

(Effects of the invention) As is clear from the above explanation, the present invention includes a distribution collar that is inserted into each heat transfer tube while maintaining an annular space between the heat transfer tubes passing through the distribution chamber, and the through hole is aligned with the axis of the distribution collar. Since it is formed in a direction that crosses the center and coincides with the tangent line of the heat transfer tube, it is possible to form a uniform and stable liquid film on the outer surface of the heat transfer surface, causing dry patches on the outer surface of the heat transfer tube. First, it has the excellent effect of maintaining stable performance of the evaporator.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the components of an ocean thermal power generation plant, Figure 2 is a sectional view showing the main parts of a conventional falling film evaporator, and Figure 3 is a diagram showing the main parts of a conventional falling film evaporator. 4 is a cross-sectional view showing an example of a falling film type evaporator according to the present invention, and FIG. 5 is a cross-sectional view showing an example of the fluid distribution means used.
- It is a sectional view along the V line. 23...Evaporator shell, 24...Heat transfer tube, 26...
Distribution room, 31... Partition plate, 32... Distribution port, 33
...Putskin, 35...Distribution collar, 36...Annular space, 37...Through hole.

Claims (1)

[Scope of utility model registration request] A cylindrical evaporator body, an upper water chamber partitioned into the upper part of the evaporator body, and an upper water chamber connected to the lower side of the upper water chamber and extending from the water chamber to the lower water chamber below. a distribution chamber that accommodates a certain section near the upper ends of a large number of heat exchanger tubes, and has a distribution port through which the supplied evaporated liquid is deposited in a film form on the outer surface of each of the heat exchanger tubes;
The distribution chamber includes a plurality of through holes that are fitted into each of the heat transfer tubes passing through the distribution chamber while maintaining an annular space therebetween to adjust the flow rate of the evaporated liquid supplied to the heat transfer tubes. a distribution collar, and the through hole extends in a direction that crosses the axis of the distribution collar and coincides with a tangent to the heat exchanger tube so that the evaporated liquid is supplied to the outer surface of the heat exchanger tube as a swirling flow. A falling film evaporator characterized in that: