JP2979105B2 - 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, in the heat recovery device, the efficiency increases as the evaporating temperature of the working medium approaches the heat source temperature, so that the non-azeotropic mixture is used as the working medium instead of the working medium composed of a single component, thereby obtaining the heat from the evaporator. Higher steam temperatures have been used. As an example of such a heat recovery device, there is disclosed a binary power generation system which 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., published in Japanese Unexamined Patent Publication No.
This system, as shown in FIG. 3, 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 The steam, which has been cooled to a low temperature and a low pressure after the work, is discharged from the steam turbine (2) and proceeds to the condenser (3), where it is deprived of heat 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. 4, this known evaporator has 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 non-azeotropic mixture outlet (15) of the evaporator (11), and a non-azeotropic mixture of the evaporator (11) from the liquid outlet of the gas-liquid separator (16). A reflux tube (18) leading to the mixture inlet (14) and a variable throttle (1
The variable throttle (17) regulates the amount of reflux liquid to maintain the optimal thermodynamic concentration of the non-azeotropic mixture in the evaporator. This evaporator is of a natural circulation type, in which the working medium in the liquid phase is supplied to the working medium passage (12) from the lower inlet (14), and the generated steam is supplied from the upper outlet (15) to the gas-liquid separator (16). ), And is separated into vapor and unevaporated liquid by the gas-liquid separator (16). The unevaporated liquid passes through the reflux pipe (18) and the variable throttle (17) and passes through the working medium inlet (14). Reflux to (12).

[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 pressure of the non-evaporated liquid is lower than the liquid pressure at the inlet of the evaporator, it cannot be returned to the inlet of the evaporator as it is. Moreover, if the high-temperature unevaporated liquid is directly mixed with a low-temperature supply liquid containing a large amount of low-boiling components, a low-boiling component vapor is generated in the piping, so that an air lock is easily generated.

[Means for solving the problem]

The non-azeotropic mixture evaporator of the present invention is a falling liquid film type plate evaporator, in which a non-evaporated liquid is guided to a liquid supply line via a mixer by a pump and forcedly circulated. Features.

[Action]

In a falling liquid film type plate evaporator, liquid is supplied to a vapor passage from an upper portion, and flows down in a thin film form along a 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 leaves the heat transfer surface and accumulates in the passage. Therefore, the vapor and the liquid flow separately in the passage.

The non-evaporated liquid is led to a liquid supply line by a pump.
At this time, by passing through the mixer, the high-temperature unevaporated liquid and the low-temperature supply liquid are mixed to make the temperature uniform and to mix while suppressing evaporation of low-boiling components. Even if bubbles are generated, they are absorbed into the cold liquid by vigorous turbulent heat transfer.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a falling liquid film type plate evaporator in which a steam passage (22) and a heat source passage (23) are alternately formed via a heat transfer wall (21). Is generally indicated by reference numeral 20. Steam passage (2
2) communicates with the liquid supply port (24) at the top, and discharge port (2
It communicates with 5). A gas-liquid separator (2
6) is provided, and the vapor outlet (2
7) is connected to appropriate steam utilization equipment such as a steam engine.
On the other hand, the liquid outlet (28) of the gas-liquid separator (26)
Is connected to the suction side. The discharge side of the pump (29)
It is connected to a mixer (30) provided in the liquid supply line (31). As the mixer (30), for example, an in-line mixer as shown in FIG. 2 can be used.
An in-line mixer is a mixer that can be easily attached to a part of a pipeline, and promotes turbulent flow of a fluid passing through the inside of the mixer, causing fluid particles to move irregularly and mix with each other. It has such a structure.
For this reason, the low-temperature supply liquid and the high-temperature unevaporated liquid are uniformly mixed and the temperature changes uniformly. Therefore, evaporation of low boiling components in the supply liquid is suppressed. Even if bubbles are generated, the bubbles are absorbed into the cold liquid by vigorous turbulent heat transfer.

The heat source fluid is supplied from a supply port (33) below the shell (32) surrounding the plate group, passes through a heat source passage (23),
It is discharged from the upper outlet (34).

〔The invention's effect〕

As described above, in the present invention, since the unevaporated liquid is guided to the liquid supply line via the mixer by the pump and forcedly circulated, the high-temperature unevaporated liquid is supplied to the low-temperature supply liquid.
It can be returned without generating bubbles. Therefore, a falling liquid film type plate evaporator suitable 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, FIG. 2 is a schematic sectional view of an in-line mixer, and FIGS. 3 and 4 are block diagrams showing a conventional example. 20: Falling liquid film type plate evaporator 21: Heat transfer wall 22: Vapor passage 23: Heat source passage 24: Liquid supply port 25: Discharge port 26: Gas-liquid separator 29: Pump 30: Mixer 31: Liquid supply line

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

Claims (1)

(57) [Claims] 1. An evaporator for a non-azeotropic mixture, wherein a non-evaporated liquid is forcibly circulated to a liquid supply line via a mixer by a pump in a falling liquid film type plate evaporator.