JP2979104B2 - Non-azeotropic evaporator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an evaporator for evaporating a non-azeotropic mixture. Here, the non-azeotropic mixture means an azeotropic mixture, that is, a two-component or multi-component mixture other than a gas mixture having a point where the liquid composition and the vapor composition become equal in a gas-liquid equilibrium state.

[Conventional technology]

It is known to use non-azeotropic mixtures as working media for heat recovery devices. In other words, since the efficiency of the heat recovery device increases as the temperature difference increases, the evaporation temperature obtained from the evaporator should be increased by using a non-azeotropic mixture as the working medium instead of the working medium consisting of a single component. Has been done. As an example of such a heat recovery device, there is disclosed a binary power generation system that operates based on a Rankine cycle using a working medium such as chlorofluorocarbon or the like as a heat source, using warm wastewater discharged from a factory, geothermal water, or the like as a heat source.
No. 94. This system, as shown in FIG. 2, connects a closed working medium loop by connecting an evaporator (1), a steam motor such as a steam turbine (2), a condenser (3) and a pump (4) in series. The working medium is circulated in the working medium loop.
Then, the working medium in the liquid phase evaporates by removing heat from the heat source fluid in the evaporator (1), and the generated high-temperature and high-pressure steam is supplied to the steam turbine (2) to drive the generator (5). Used for After the work, the low temperature and low pressure steam
When discharged from the steam turbine (2), it proceeds to the condenser (3), where heat is taken by the cooling water and condensed. The condensate is sent again to the evaporator (1) by the pump (4).

On the other hand, an example of an evaporator for a non-azeotropic mixed medium is disclosed in
-79810. As shown in FIG. 3, the known evaporator includes an evaporator (1) in which a non-azeotropic mixture to be evaporated and a fluid as a heat source flow in completely counterflow.
1), a gas-liquid separator (16) connected to the outlet (15) of the evaporator (11), and an evaporator (1) from the liquid outlet of the gas-liquid separator (16).
The return pipe (18) leading to the inlet (14) of 1) and the return pipe (1)
8) A variable throttle (17) provided in the middle of the process, and the optimal thermodynamic concentration of the non-azeotropic mixture in the evaporator (11) is maintained by adjusting the amount of the reflux liquid with the variable throttle (17). I am trying to do it. This evaporator is a natural circulation type,
The working medium in the liquid phase is supplied to the working medium passage (12) from the lower inlet (14), and the adjacent working passage (13) via the heat transfer wall.
Evaporates by removing heat from the heat source inside, and the generated vapor is led from the upper outlet (15) to the gas-liquid separator (16), where it is separated into vapor and unevaporated liquid The unevaporated liquid is returned to the passage (12) from the working medium inlet (14) through the reflux pipe (18) and the variable throttle (17).

[Problems to be solved by the invention]

Since the liquid and the generated vapor exist in a two-phase flow state in the passage (12) of the working medium, it is difficult to control the evaporation. Therefore, the present invention is to prevent the evaporation from being performed in a state where the vapor and the liquid are separated by supplying the working medium liquid from the upper part of the passage (12) and flowing down the heat transfer surface in a thin film form. For that purpose, how to return the unevaporated liquid to the liquid supply line becomes an issue. Since the unevaporated liquid has a lower pressure than the liquid pressure at the inlet of the evaporator, it cannot be returned to the inlet of the evaporator as it is. It is conceivable to apply forced circulation by applying pressure by a pump, but in this case, not only is extra power required for driving the pump, but there are also the following problems. Since this non-evaporated liquid is in a saturated state and bubbles are easily generated, it is necessary to secure a sufficient height of the pushing liquid to prevent bubbles from being generated when forced circulation is performed by a pump. The required space in the height direction must be large.

[Means for solving the problem]

The present invention has a vapor passage and a heat source passage adjacent to each other through a heat transfer wall, and connects a liquid supply line to a liquid supply port communicating with an upper portion of the vapor passage, and a discharge passage communicating with a lower portion of the vapor passage. A gas-liquid separator is provided, and while the liquid supplied to the exhaust passage flows down the heat transfer wall and takes heat from the heat source fluid flowing in the adjacent heat source passage to evaporate, the generated steam and the unevaporated liquid are vaporized. A falling film type plate evaporator for a non-azeotropic mixture composed of two or more components having different boiling points, which is configured to enter a gas-liquid separator from an outlet at a lower portion of a passage, wherein an ejector is provided in a liquid supply line. The apparatus is characterized in that unevaporated liquid in the gas-liquid separator is guided to the liquid supply port of the evaporator and forcedly circulated using the liquid supplied to the liquid supply port through the liquid supply line as a driving fluid.

[Action]

In a falling liquid film type plate heat exchanger, liquid is supplied from above and flows down in a thin film form along the heat transfer surface of the plate. In the meantime, the heat source fluid deprives the heat source fluid of evaporation heat via the heat transfer surface and evaporates. The generated steam accumulates in the passage away from the heat transfer surface. Therefore, the vapor and the liquid flow separately in the passage.

Unevaporated liquid is led to a liquid supply line by an ejector. That is, the ejector connected to the liquid supply line
The velocity energy of the liquid ejected at a high speed from the nozzle is converted into pressure energy to suck the unevaporated liquid and discharge it toward the liquid inlet.

In the case of a non-azeotropic mixture, the state of a single component fluid is defined by pressure and temperature, while the state of each component changes with the concentration. In particular, since the unevaporated liquid separated from the vapor as the evaporation residue has various concentrations, when circulating by a pump, it is necessary to secure a sufficient height of the pushing liquid to prevent the generation of bubbles. On the other hand, since the present invention uses an ejector, even if air bubbles are generated, there is no adverse effect on the function.Moreover, since the supply liquid serving as the driving fluid has a lower temperature than the unevaporated liquid, it is mixed with the unevaporated liquid to form bubbles. Is cooled and liquefies easily.

〔Example〕

Referring to the drawings, an embodiment of the present invention will be described. In FIG. 1, a falling liquid film plate type evaporator in which steam passages (22) and heat source passages (23) are alternately formed via heat transfer walls (21) is shown. It is generally indicated by reference numeral 20. Steam passage (22)
Communicates with the liquid supply port (24) at the top, and the discharge port (25) at the bottom
Is in communication with The discharge port (25) is provided with a gas-liquid separator (26), and the steam outlet (27) of the gas-liquid separator (26) is connected to a suitable steam utilization device such as a steam engine. On the other hand, the liquid outlet (28) of the gas-liquid separator (26) is connected to the ejector (30). The ejector (30) is provided in a liquid supply line (29) for supplying a liquid to a liquid supply port (24). The ejector (30) converts the velocity energy of the liquid ejected from the nozzle at a high speed into pressure energy and performs non-evaporation. Aspirate and drain the liquid. The heat source fluid is supplied from the lower supply port (34) of the shell (32) surrounding the plate group, and is discharged from the upper discharge port (36) via the heat source passage (23).

〔The invention's effect〕

As described above, the present invention uses an ejector to return the unevaporated liquid to the inlet of the evaporator. Therefore, unlike the case of forced circulation by a pump, the present invention does not involve an increase in required power and prevents cavitation. It is not necessary to secure the height of the liquid to be pushed in, so that an extra space is not required and a falling film type plate evaporator for a non-azeotropic mixture can be constituted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are block diagrams showing a conventional example. 20: Falling liquid film type plate evaporator 21: Heat transfer wall 22: Steam passage 23: Heat source passage 24: Liquid supply port 25: Discharge port 26: Gas-liquid separator 29: Liquid supply line 30: Ejector

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-172185 (JP, A) JP-A-62-280501 (JP, A) JP-A-55-95002 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) F01K 25/10 F22B 1/16

Claims (1)

(57) [Claims] 1. A discharge port having a vapor passage and a heat source passage adjacent to each other via a heat transfer wall, connecting a liquid supply line to a liquid supply port communicating with an upper portion of the vapor passage, and communicating with a lower portion of the vapor passage. The liquid supplied to the vapor passage is taken down from the heat source fluid flowing in the adjacent heat source passage while the liquid supplied to the vapor passage flows down the heat transfer wall and evaporates. A falling liquid film type plate evaporator for a non-azeotropic mixture composed of two or more components having different boiling points, which is adapted to enter a gas-liquid separator from an outlet at a lower part of a vapor passage, wherein an ejector is connected to a liquid supply line. The liquid supplied to the liquid supply port through the liquid supply line is used as a driving fluid, and the unevaporated liquid in the gas-liquid separator is guided to the liquid supply port of the evaporator and forcedly circulated. Evaporator for boiling mixtures.