JPS59212601A - Falling liquid-film type evaporator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a falling liquid model evaporator used in a total low heat drop power generation plant that uses low heat drop energy such as seawater temperature difference to generate electricity. The present invention relates to, in particular, improvements to heat exchanger tubes.

[Technical background of the invention and its problems] Figure 7 is a schematic system diagram of an ocean temperature difference power generation plant that uses temperature differences in seawater to generate electricity. The fluid is heated and evaporated by relatively high temperature seawater in the ocean surface layer in the evaporator/,
The steam is introduced into the steam turbine 3 through the steam control valve 2, where it performs expansion work and drives the steam turbine 3, which rotates the generator and generates electricity.

On the other hand, the steam discharged from the steam turbine 3 is sent to the condenser j
It is condensed by relatively low-temperature seawater in the deep ocean,
The condensed water is once stored in the tank B and then returned to the evaporator by the circulation pump 7. Here, the amount of evaporation from the evaporator is always kept constant, and when the generator's load fluctuates, the driving force of the steam turbine 3 can be reduced by opening and closing the turbine pass valve ♂. This can be done by adjusting.

By the way, as an evaporator in this kind of plant,
The use of plate type, pool boiling type, or falling film type evaporators has been proposed. However, in general, these ocean temperature difference power generation plants have low plant efficiency, require a large installation space, and as the turbine output increases, the equipment becomes bulky, making it difficult to install on land. In addition, in these ocean temperature difference power generation plants, the slight increase or decrease in pressure loss on the seawater side affects the output of the turbine at the transmission end, so it is not a good idea to pump the intake seawater to land. For this reason, offshore installations are being considered for large plants. In this case, each of the above-mentioned equipment is installed on the purge, so it is necessary to arrange the equipment in a con- nected manner. Use of an evaporator is effective.

FIG. 2 is a schematic configuration diagram of the falling film evaporator 10. Inside the casing // of the falling film evaporator 10, there are partition walls /, 2, /3, /'i4 in order from the top. Heating fluid inflow chamber/S, heated fluid inflow chamber/6, evaporation chamber/
7 and a heating fluid outlet chamber/are respectively formed into sections, and the heating fluid inflow chamber 15 and the heated fluid inflow %
A heated fluid introduction pipe tsh and a heated fluid introduction pipe /Aa are connected to /6, respectively. Further, a vapor outlet pipe/7a is connected to the evaporation chamber/7 at an intermediate height position,
A heated fluid outlet pipe/7b is connected to the lower part, and a heated fluid outlet pipe/zone is connected to the heated fluid outlet chamber/zone.

On the other hand, a large number of heat transfer tubes/9 are arranged inside the casing///, the top end of which opens into the heating fluid inlet chamber 15, and the lower end of which opens into the heating fluid outlet chamber 7g.

The above heat exchanger tube/? As shown in Figure 3, the outer surface of the
A large number of uneven grooves/9a extending in the axial direction are formed to improve the heat transmission coefficient.

Therefore, the surface seawater, which is the heating fluid, enters the heating fluid inlet chamber.
The fluid is supplied to S, flows through the heat exchanger tube, and is discharged outside the vessel through the heated fluid outlet chamber. On the other hand, the heated fluid flows into the heated fluid inlet chamber/6 through the heated fluid introduction pipe/6a and is stored on the partition wall/3, and from the gap between the partition wall/3 and the heat transfer tube/9. It flows down along the outer surface of each heat exchanger tube 17 and is heated by exchanging heat with the heating fluid flowing inside the heat exchanger tube /q, and a part of it is evaporated. The evaporated fluid to be heated is supplied to the evaporation turbine through the steam outlet pipe/7a, and the fluid to be heated that has not been evaporated flows out from the fluid to be heated pipe/7b and is heated again via a pump (not shown). The heated fluid is refluxed to the inlet chamber/B.

However, with such a falling film evaporator, the power generation end output is 2.
When applied to a r00 KW plant, the number of heat transfer tubes: yooθ Total length of heat transfer tubes: /7m Total height of evaporator: 20t1: Evaporator shell diameter: Am assembled weight:
It will be a fairly large structure. Therefore, it is difficult to install such a large structure on the purge.
unfavorable in terms of strength and stability.

[Purpose of the invention]

In view of these points, it is an object of the present invention to provide a falling film type evaporator that can be sufficiently installed on the purge, has high heat transfer efficiency, and is highly conducive.

[Summary of the invention]

The present invention provides a falling film type evaporator that heats a heated fluid flowing down along the outer surface of the heat transfer tube by a heating fluid flowing down inside the heat transfer tube, in which a heating fluid flowing down the heat transfer tube is heated on the outer surface of the heat transfer tube in the evaporation chamber. It is characterized in that a porous layer 7 is provided over a suitable height range in the half part, and an uneven groove extending in the tube axis direction following the porous layer is formed in the lower half part.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. In addition, in FIG. 2, the same parts as in FIG. 2 are given the same reference numerals, and detailed explanation thereof will be omitted.

Fig. 7 is a vertical cross-sectional view of the falling liquid model evaporator of the present invention, in which the outer surface of a large number of heat transfer tubes /9 arranged in the casing // has an upper half thereof in the evaporation chamber /7. Porous layer 2/
is formed, and a large number of uneven grooves U extending in the tube axis direction following the porous layer 2/ are formed in the lower half thereof. Other points are exactly the same as the conventional one shown in FIG.

- By the way, the porous layer 2/ is made of copper or copper alloy powder with a particle size of 200 mcs or less, 5-o-3-00 μm.
The uneven grooves are formed by flame spraying to a thickness of 0-3~/, 0711jA/~/, J
-711JR (provided at The outer diameter D1 of the main pipe of the part and the maximum outer diameter D2 of the uneven groove U forming part are formed to have the same size, and the thickness of the porous layer U/ is gradually reduced from a predetermined value to completely reduce its thickness. The groove depth of the uneven groove n is gradually increased from the position where the thickness becomes zero, until the predetermined groove depth is 0.3.
~/''.

The heated fluid that has flowed into the heated fluid inflow chamber /6 flows out from the gap between the partition wall /3 and the heat exchanger tube /9, flows down while covering the heat exchanger tube /9 in a film-like manner, and flows down into the porous layer 27. The water is heated by the surface seawater flowing inside the pipe and undergoes nucleate boiling.
Some of it evaporates. The unevaporated liquid is further heated by the surface seawater flowing inside the pipe in the uneven groove 22 portion, and a part of the remaining liquid is further evaporated. ) is derived from On the other hand, the steam evaporated on the surface of the heat transfer tube 19 is sent to the steam turbine via the steam outlet tube/7a.

In this case, since the heat exchanger tube 19 is configured as described above, the liquid film flowing down the outer surface of the tube is lower than the tube surface at the transition part.
The entire amount effectively contributes to heat transfer without peeling, improving its thermal efficiency.By the way, Figure 6 shows the results of a performance test of the falling liquid film heat transfer coefficient of a heat transfer tube with uneven grooves on the outer surface. is a diagram showing the pitch of the uneven grooves from 7 to /,
! Heat transfer performance is highest in the eyebrows.

Furthermore, Figure 7 shows the results of a test conducted using Freon//3 as the working fluid (heated fluid) to determine the change in the heat transfer coefficient of the falling liquid film on the outside of the tube with respect to the temperature difference between the heating fluid and the heated fluid. In the line sections shown, (a) is the test result of a heat exchanger tube with only uneven grooves on the outer surface of the tube, and (b) is the test result of a heat exchanger tube with only a porous layer formed by thermal spraying on the outer surface of the tube. Results 2 are shown. Zunawaji.

In areas where there is a large temperature difference between the surface seawater and the working fluid, heat transfer tubes with porous layers exhibit high heat transfer performance, and when the temperature difference becomes small, heat transfer tubes with uneven grooves exhibit high heat transfer performance. .

Therefore, if the heat transfer tube is configured as described above, the heat transfer coefficient of the falling liquid film on the outside of the tube will be as shown in Figure g, achieving a higher heat transfer efficiency than the conventional heat transfer tube provided with only uneven grooves. can do. Furthermore, due to the high heat transfer efficiency as described above, when the falling film evaporator of the present invention is applied to a plant with a power generation output of 2300 kW, the number of heat transfer tubes: 2000 total length of heat transfer tubes /3 m Evaporation Overall height of vessel / m Evaporator shell weight A tyt Assembled weight t, t! ;OTon, and the total height of the evaporator and assembly weight can be significantly reduced.

〔Effect of the invention〕

As explained above, in the present invention, a porous layer is provided over an appropriate height range on the outer surface of the upper half of the heat exchanger tube in the evaporation chamber, and the porous layer is followed by unevenness extending in the tube axis direction. Since the grooves are formed, the heat transfer coefficient of the falling liquid film on the outside of the tube is 7. ! It is possible to improve the performance by about 2 times, thereby reducing the total height of evaporation and the assembly weight, reducing the influence on the strength of purge when installed at sea, and improving stability.

[Brief explanation of drawings]

Figure 1 is a schematic system diagram of an ocean temperature difference power generation plant, Figure 2 is a vertical cross-sectional view of a conventional falling film evaporator, Figure 3 is a cross-sectional view of the heat transfer tube of the evaporator, and Figure A vertical cross-sectional view of the falling film type evaporator of the present invention, FIG. 5 is a vertical cross-sectional view of the transition part of the heat transfer tube of the same evaporator, and FIG. Change diagram, Figure 7 is a change diagram of the liquid jet heat coefficient created by outside the tube ff111 for the temperature difference between the heating fluid and the heated fluid, and Figure R shows the heat transfer performance of the heat transfer tube in the present invention. FIG. 15... Heating fluid inflow chamber, /6... Heated fluid inflow chamber, /7... Evaporation chamber, /9... Heat exchanger tube, 2/...
Porous layer, texture... uneven grooves. Applicant's representative Inomata Kiyomi 1 Bacteria 3 Iku" No. 4 (15)

Claims (1)

[Scope of Claims] 1. In a falling film evaporator that heats a fluid to be heated flowing down along the outer surface of the heat transfer tube by a heating fluid flowing down inside the heat transfer tube, the heat transfer tube in the evaporation chamber A falling liquid film type, characterized in that a porous layer is provided over an appropriate height range on the upper half of the outer surface of the tube, and an uneven groove extending in the tube axis direction following the porous layer is formed on the lower half of the tube. Evaporator. The porous layer has a grain size on the outer surface of the heat transfer tube! 2. The falling film evaporator according to claim 1, wherein the falling film evaporator is formed by flame spraying copper or copper alloy powder having a thickness of 50 to 0 μm. 3. The uneven groove has a pitch of /~/, J-M, groove depth of 0.3~/
, OI/IJI.A falling film evaporator according to claim 1, wherein the falling film evaporator is OI/IJI. At the transition part from the porous layer to the uneven groove, the thickness of the porous layer gradually decreases, and from the position where the thickness of the porous layer reaches zero, the groove depth gradually increases until it reaches a predetermined groove depth. A falling film type evaporator 0 according to claim 1, characterized in that: