JPH01305292A - Direct contact type condenser - Google Patents

Abstract

PURPOSE:To increase the surface area of cooling medium remarkably and improve heat transfer efficiency, by a method wherein a dispersing device, reducing the particle size of dropping cooling medium, is provided below a converting device colliding the cooling medium against the outlet side opening of an injection pipe and guiding it downwardly. CONSTITUTION:Cooling medium is guided into an inlet water chamber 2 from an inlet port 8 and is ejected out of an outlet side opening through an injection pipe 3. The medium collides against bowl type caps 11 at the opening of the injection pipe 3 and is spread while the medium changes the moving direction thereof downwardly and drops on a wire net 13. The medium, dropped on the wire net 13, passes through the wire net and becomes drops of liquid having small grain size and, further, passes sequentially through the lower wire nets 14, 15. In this process, the drops of liquid. whose grain sizes have been reduced, contact directly with vapor from the upper part of the cylinder 1 of a condenser whereby the heat of the vapor is deprived and the vapor is condensed. According to this method, the surface area of cooling medium contacting with the medium to be cooled may be increased remarkably and a condensing heat transfer efficiency may be increased.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a heat exchanger, and more specifically, the present invention relates to a heat exchanger, and more specifically, a cooling medium is brought into direct contact with a medium to be cooled led to the upper part of the device, and heat exchange is performed. The present invention relates to a direct contact condenser configured to do so.

(Conventional technology) Ocean thermoconversion power generation, which is attracting much attention and research and interest in research and development aimed at acquiring new energy sources, is based on the temperature difference between warm seawater on the surface of the ocean and cold seawater in the deep layer. (Usually 20
~25℃) to obtain steam and guide it to a steam turbine to generate power. There are various cycle configurations such as open cycle, closed cycle, mist lift cycle, and combined cycle. is proposed. Among these, the open cycle method introduces warm seawater into a flash evaporator kept in a vacuum and evaporates it by itself, then leads the generated steam to a steam turbine where it is expanded under an appropriate pressure, and finally condensed. The structure is such that all vapor is condensed in the vessel.

Here, if this condenser is constructed using a surface contact method, the steam condenses on the heat transfer surface, so the condensed liquid becomes almost pure water, and as a side effect, it becomes possible to produce fresh water.
It can also function as a so-called seawater desalination device.

On the other hand, if the above-mentioned condenser is a direct contact type, fresh water cannot be obtained, but since there is no solid heat transfer surface during the condensation process, the efficiency can be significantly improved. , it is possible to remove one of the bottlenecks in ocean thermal power generation. That is, according to this method, the condensing temperature is always lower than in the direct contact method, and the heat drop of the steam turbine is increased, so that the amount of power generation per unit time can be increased by a certain value.

Furthermore, as mentioned above, the open cycle method uses steam produced by self-evaporating seawater as the operating medium, and since the temperature of warm seawater is 25 to 30°C, the maximum steam pressure of the cycle is 100 minutes below atmospheric pressure. I can only get about 1 to 3 of
Therefore, it is necessary to maintain a vacuum throughout the cycle.

Also, in order to obtain the required output under such low steam pressure, a large amount of steam is required, for example, 1k
It is necessary to generate about 70 kg of steam per hour for the amount of power generated in W. If all of this is to be condensed in a condenser using cold seawater brought from the deep layer, it is necessary to pump up 1 ton of cold seawater per hour.

When condensing such large amounts of steam, the first consideration is that an optimal structure must be used to keep pressure losses to a minimum on both the steam and seawater sides. If the pressure loss of steam becomes large, the condensation temperature will become extremely high and the output will decrease. On the other hand, if the pressure loss on the cold seawater side increases, the power of the pump that pumps up the seawater will increase, and the power consumed by the station power will increase, leading to a decrease in the amount of power generation.

Conventionally, the following types of direct contact type condensers that are applied to this open cycle are known (for example,
ASME/JSME Thera+al Engine
eringJoint Conf'erence 19
83 vol12 p301-314).

(+) Falling liquid film method (2) Downward jetting method (3) Upward jetting method (4) Packed bed method Here, in methods (1) and (2), a cold seawater distributor is installed in the upper part of the condenser. A slit or spray nozzle is arranged in this distributor, and the cold seawater is made to flow down in the form of a film or jet and come into contact with the steam in the condenser. In addition, in the method (3), as shown in Fig. 4, a number of jet pipes 3 are arranged inside the condenser side 1 and communicate with the inlet water chamber 2, and cold seawater is passed through the jet pipes 3 into the vessel. It is configured to eject upwards. Note that the reference numeral 4 in the figure indicates a tube plate. Furthermore, in method (4), the condenser is filled with a packing having voids, and cold seawater flows from above, while steam flows from below, and the cold seawater and steam flow down the surface of the packing. It was designed to make contact with the public.

Of the above four methods, the upward jetting method (3) does not use means such as manifolds in the steam flow path, so there is less pressure loss on the steam side.
In other words, since it only passes through the ejection pipe 3, it has the advantage that there is less pressure loss on the seawater side compared to other methods, and in addition to this, the structure is simple + 41, and it also has excellent performance. has been highly evaluated, and is currently considered the most promising condenser for ocean thermal power generation plants.

(Problem to be Solved by the Invention) By the way, in an open cycle type ocean temperature difference power generation plant, a boiler used in a normal thermal power plant is used to self-evaporate warm seawater under a pressure close to vacuum. Compared to steam, steam contains a large amount of aerobic gases (air, oxygen, carbon dioxide, etc.). Most of these gases are noncondensable gases, which are led to the condenser together with the expanded steam in the steam turbine and remain there without being condensed. And when these noncondensable gases increase,
They become present during the contact between steam and cold seawater, significantly impairing the heat transfer performance of the condenser. For example, there is data showing that in a direct contact type condenser, if about 1% of non-condensable gas exists, the condensation heat transfer efficiency will be about 50% or less.

This phenomenon of retention of non-condensable gas brings about the following results in the case of the above-mentioned upward jet type condenser. That is,
Figure 5 shows a jet of cold seawater spewing out from the spouting pipe 3. Here, the cold seawater rises inside the spouting pipe 3 and spews out from the opening into the condenser, resulting in the flow as shown in the figure. It flows down while maintaining a columnar or film-like liquid film. At this time, the vapor comes into contact with the surface of the liquid film, but in such a fluid state, the contact area with the vapor is small, and the flow is very stable, so noncondensable gas remains at the gas-liquid interface. Easy to do. For this reason, contact between the two is hindered and the condensing heat transfer efficiency is significantly reduced.

On the other hand, in a stable columnar or film-like flow, a temperature boundary layer is formed at the gas-liquid interface, and in this case, condensation heat transfer is dominated by mass transfer in the temperature boundary layer formed on the liquid side surface. This temperature boundary layer is formed within a few microseconds after the surface is formed, and the condensation ability is lost within a very short time.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a direct contact condenser that increases the contact area between a cooling medium and a medium to be cooled that is condensed thereby, thereby improving condensation heat transfer efficiency. .

[Structure of the Invention] (Means for Solving Communication Issues) The direct contact condenser according to the present invention has an inlet side connected to an inlet water chamber in a condenser body, and an outlet side opening connected to an upper part of the condenser body. In a direct contact condenser having a plurality of ejection pipes facing the space, an inversion device is provided opposite the outlet opening of each ejection pipe to collide the cooling medium and guide it downward. It is characterized by the provision of a plurality of dispersion devices that convert the cooling medium falling below the reversing device into droplets with small particle diameters.

(Function) The cooling medium ejected from the outlet side opening of the ejection pipe collides with the reversing device, is changed into a downward flow, and falls downward. Further, at this time, the surface area of the liquid film is also expanded by the reversing device so that the flow of the cooling medium has a sufficient spread with respect to the diameter of the ejection pipe.

The cooling medium then impinges on one of the distribution devices below the inversion device, ie the one located at the top stage.

The dispersion device is, for example, a wire gauze with a very fine mesh, and all of the cooling medium that passes through it is converted into droplets with small particle sizes. At this time, the size of one droplet of liquid can be made to any size by appropriately selecting the size of the mesh. After that, the droplets with small particle size come into direct contact with the medium to be cooled, and the medium to be cooled is condensed, and while they are mixed, they fall further to the dispersion device installed below. The temperature boundary layer formed at the gas-liquid interface is destroyed by the subsequent dispersion device, so a new heat transfer surface is formed each time. Therefore, all factors that inhibit heat transfer are removed, making it possible to obtain high condensation heat transfer efficiency.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes the condenser side, and the condenser side 1 is provided with an inlet water chamber 2 in its center.

A plurality of ejection pipes 3 are provided above the inlet water chamber 2 via a tube plate 4, the inlet openings of which communicate with the artificial water chamber. Further, an outlet water chamber 6 is provided on the outside of the condenser side 1 and communicates with the inside of the vessel via a passage 5, and a duct 7 is arranged above the passage 5 of the outlet water chamber 6. . In the figure, numeral 8 is the seawater inlet, numeral 9 is the seawater outlet, and numeral 1 is the seawater inlet.
0 indicates each gas outlet.

On the other hand, FIG. 2 shows details of the ejection pipe 2 and the devices associated therewith, that is, the reversing device and the dispersing device.

That is, as a reversing device, a bowl-shaped cap 11 that is wide open toward the outlet side opening of the ejection pipe 3, that is, a hemispherical cap 11 whose entire interior has been removed, is attached to the opening of each ejection pipe 3. The opening of this cap 11 is connected to the upper surface of a support piece 12a provided at the tip of the ejection tube 3, and its position is fixed. Further, as a dispersing device, a wire mesh 13 is attached so as to be sandwiched between the supporting piece 12a and the corresponding supporting piece 12b. Further, below the wire mesh 13, a wire mesh 14 and a wire mesh 15 are provided at a constant interval via support pieces 16a, 16b and support pieces 17a, 17b.

Next, the operation of the condenser configured as described above will be explained.

The cold seawater is led from the seawater population 8 to the inlet water chamber 2, flows upward therein, passes through the spout pipe 3, and is spouted out from the outlet side opening. At this time, the cold seawater enters the bowl-shaped cap 11 that is wide open toward the opening of the spout pipe 3, collides with the inner surface of the bowl-shaped cap 11, spreads, changes direction downward, and enters the cap 11.
It falls onto the wire mesh 13 provided directly below. The cold seawater that has fallen onto the wire mesh 13 passes through the mesh and becomes droplets with small particle diameters, which then sequentially pass through the wire mesh 14 and the wire mesh 15 provided below. In this process, the droplets whose particle size has become smaller come into direct contact with the steam flowing from the upper part of the condenser side 1, and the steam is deprived of heat and condensed.

On the other hand, the temperature of the cold seawater rises due to the heat given by the steam, and the two mix together as they fall onto the tube plate 4, and then further into the passage 5.
through which it is led to the outlet water chamber 6. The free gases in the steam also enter the duct 7 from the bottom of the tube bank and are discharged from there to the gas outlet 9.

By the way, such repeated wire mesh 13.14.1
Due to the dispersion effect of cold seawater using the condenser 5, the condensation efficiency of the condenser of this embodiment is improved as follows compared to that of the prior art.

That is, FIG. 3 shows the results of an investigation of how the condensation efficiency changes depending on the speed of cold seawater spewed out of the jet pipe 3 between the configuration of this embodiment and the conventional technology. ing. Here, the condensation efficiency E is a value determined by the following equation.

Ti-T.

E-1□ Ti-t Here, Ti... Cold seawater inlet temperature To...
...Cold seawater outlet temperature t...Condensing temperature The content shown in this figure shows that the closer the value of condensing efficiency E is to 1, the lower the condensing temperature t can be expected, and the higher the condensing heat transfer efficiency. ing. In other words, when the value of condensation efficiency E increases, the condensation temperature t becomes lower at the same cold seawater flow rate than when this value is low, and the turbine heat drop can be increased accordingly, resulting in a reduction in turbine output. There will be an increase.

Here, those according to the prior art are indicated by dashed lines.

On the other hand, the one according to this embodiment is represented by a solid line. Comparing the two, it is clear that the solid line approaches 1, indicating that the one according to this example is superior. For example, when the ejection velocity v0 of cold seawater is 1.5 m/3, the condensation efficiency E is approximately 7.2 according to the conventional technology and approximately 9.7 according to this embodiment, which is an improvement of more than 3 times. will be done.

Note that much of this improvement in condensation efficiency E is due to increasing the surface layer by dispersing the cold seawater, but this is not entirely due to the steam rectification effect of the outer surface of the cap 11. Some of this is due to the addition.

Further, instead of the bowl-shaped cap 11 in the above embodiment, a dish-shaped cap, a conical cap, etc. may be used, and the function of the reversing device of the present invention may be realized by these means.

On the other hand, the same function as the wire mesh 13.14.15 of the above embodiment can be obtained by using a plate material with a large number of slits or holes, a bundle of wires or needle-like protrusions, etc. instead of the wire mesh 13.14.15. are possible, and both are embodiments of the present invention.

[Effects of the Invention] As explained above, the present invention provides a reversing device that causes the cooling medium to collide with the outlet side opening of each jet pipe and guides it downward, and a cooling medium that falls below the reversing device. Each device is equipped with a dispersion device that converts the medium into droplets with a small particle size, so the surface area of the cooling medium in contact with the medium to be cooled can be greatly increased, and there is also a temperature boundary layer that inhibits heat transfer at the gas-liquid boundary. is not formed for a long time. Therefore, according to the present invention, the excellent effect of dramatically increasing the condensation heat transfer efficiency in a direct contact condenser is achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a direct contact condenser according to the present invention, FIG. 2 is an enlarged cross-sectional view of the ejection pipe portion, and FIG. A characteristic diagram showing the condensing efficiency of the condenser, FIG. 4 is a sectional view showing an example of a conventional condenser, and FIG. 5 is an explanatory diagram showing the state of cold seawater spouted from the jet pipe. 1・・・・・・・・・・・・・・・Condensed copper 2.
・・・・・・・・・・・・・・・・Entrance water chamber 3...
・・・・・・・・・・・・・・・Ejection pipe 4・・・・・・
・・・・・・・・・・・・Tube plate 6・・・・・・・・・・・・
・・・・・・・・・Outlet water chamber 11・・・・・・・・・・・・
・・・・・・Cap 13.14.15, ・・・Wire mesh

Claims (1)

[Claims] In a direct contact condenser, a plurality of ejection pipes are provided in the condenser body, the inlet side communicating with the inlet water chamber, and the outlet side opening facing the upper space in the condenser body. A reversing device is provided opposite the outlet opening of the ejection pipe to collide the cooling medium and guide it downward, and the cooling medium falling below the reversing device is converted into droplets with a small particle size. A direct contact condenser characterized by being provided with a plurality of dispersion devices.