JPH0429842B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an apparatus for condensing a non-azeotropic mixture, and can be used, for example, in a waste heat recovery apparatus using a non-azeotropic mixture as a working medium.

BACKGROUND ART FIG. 3 shows an example of a waste heat recovery device that uses heated waste water discharged from a factory as a heat source and recovers it as power using a Rankine cycle. In this device, the working medium (e.g. fluorocarbon) is transferred to the evaporator 21,
It circulates within a system consisting of a turbine 22, a condenser 23, and a pump 24. That is, the steam of the working medium heated and generated in the evaporator 21 expands in the turbine 22 to perform work, and
The exhaust gas discharged from the evaporator 21 is cooled and condensed in the condenser 23, and then sent to the evaporator 21 again by the pump 24 to repeat the same operation. The output shaft of the turbine 22 is the load 2
5 (for example, a generator).

Problems to be Solved by the Invention In such a waste heat recovery device, the larger the temperature difference, the higher the efficiency. Efforts are being made to increase the However, in either case, it is necessary to add a separate device, which increases the cost.

This invention was developed based on the recognition of this problem, and by using a non-azeotropic mixed medium instead of the conventional single-component medium, the condensation temperature itself in the condenser can be lowered. This is what I am trying to do. Therefore, the purpose of this invention is to
It is an object of the present invention to provide a condensing device with a structure most suitable for non-azeotropic mixed media.

Means for Solving the Problems The non-azeotropic mixture condensing device of the present invention includes a circulating condenser 11 in which the non-azeotropic mixture to be condensed and cooling water flow in completely opposite flows; A gas-liquid separator 16 connected to the azeotrope outlet 15, a reflux pipe 18 communicating from the gas phase outlet of the gas-liquid separator to the non-azeotrope inlet 14 of the condenser, and a variable throttle 17 provided in the middle of the reflux pipe. The thermodynamically optimum concentration of the non-azeotropic mixture in the condenser is maintained by adjusting the amount of reflux liquid with a variable throttle.

Embodiment An embodiment of the present invention is shown in FIG. 1. Hereinafter, a case where this condensation device is used in place of the conventional condenser 23 in the already mentioned waste heat recovery device shown in FIG. 3 will be described as an example. I will explain. Note that the working medium of the waste heat recovery device in this case is a non-azeotropic mixture. Here, non-azeotropic mixtures refer to other than so-called azeotropic mixtures.
It refers to a two-component system or a multi-component system mixture.

Figure 2 shows the individual saturation temperatures of component A and component B under constant pressure, T _A and
When T _B indicates the relationship between the concentration and temperature of a non-azeotropic mixture consisting of A and B. Note that the concentration herein refers to the weight ξ of B contained per unit weight of the non-azeotropic mixture, where the weights of A and B are G _A and G _B , respectively. That is, ξ
=G _B /G _A + _G BIf the liquid phase and gas phase are in equilibrium at temperature T, the concentration of the liquid phase is calculated from the position of the point corresponding to temperature T on the liquidus line and the gas phase line. is ξl and the concentration of the gas phase is ξg. Furthermore, if the concentration of the combined liquid and gas phases is ξ, the state of this mixture is at point M
The ratio of the weight of the solution to the weight of vapor at that time is inversely proportional to the horizontal distances a and b from point M to the liquidus line and the vapor line.

Next, when point M exists within the region surrounded by the liquidus line and the vapor phase line, the mixture separates into both gas and liquid phases, but when point M coincides with both of those lines or outside that region. When it comes out, either air or liquid 1
There are only two phases. For example, point M ₁ represents an unsaturated liquid, and point M ₂ represents superheated steam. However, when the temperature changes, the state of the mixture also changes. For example, if the temperature of the unsaturated liquid indicated by point M ₁ is T ₂
If the temperature is raised above this point, it becomes a saturated solution, and if the temperature is raised above that point, it begins to evaporate. Conversely, when a gas with a concentration ξl is cooled under constant pressure, condensation begins at point d, and the composition and state of the gas phase (vapor) in equilibrium at that time is shown at point d'. When the temperature is further cooled to T ₁ , the gas phase at point h and the solution at point j coexist at a ratio of ji:ih. When cooling is continued and the temperature reaches T, only the liquid phase at point c remains, and if cooling is continued thereafter, the solution will simply be supercooled.

Referring now to FIG. 1, the condenser 11 has a working medium passage 12 and a cooling water passage 13.
The working medium and the cooling water are in a completely opposite flow relationship.
A turbine 22 is connected to the working medium inlet 14 of the condenser 11.
Working medium vapor is supplied from. A gas-liquid separator 16 is provided at the working medium outlet 15 of the condenser 11 . A liquid phase outlet of the gas-liquid separator 16 is connected to a working medium circulation pump 24 . The gas phase outlet of the gas-liquid separator 16 communicates with the working medium inlet 14 of the condenser 11 through a reflux pipe 18 equipped with a variable throttle 17 and a booster 19 .

The working medium condensed in the condenser 11 is
It passes through the gas-liquid separator 16 and then to the pump 24. The working medium vapor separated from the working medium liquid by the gas-liquid separator 16 passes through the reflux pipe 18 and returns to the condenser 11 together with the working medium vapor discharged from the turbine 22 . In this case, the pressure of the working medium vapor is increased by the pressure drop in the condenser 11 by the pressure booster 19 . Note that in the case of a heat pump in the same waste heat recovery device, it is also possible to connect the reflux pipe 18 to the suction side of the compressor and omit the booster.

Working medium inlet 14 and outlet 15 of condenser 11
Let ξl be the optimal concentration of the working medium to ensure the temperatures T ₂ and T, respectively. When working medium vapor with a concentration ξl enters the condenser 11, it first reaches the temperature T ₂ .
An initial condensate with a state indicated by d′ is generated. When the working medium vapor is cooled in the condenser 11 and reaches the temperature T, a working medium liquid is generated at each point on the liquidus line from point d' to point C. In the end, the liquid flowing from the working medium outlet 15 of the condenser 11 to the gas-liquid separator 16 changes in various states (temperature, concentration) from the initial condensed liquid shown at point d' to the final condensed liquid shown at point C.
and the vapor shown at point C'. These are separated by the gas-liquid separator 16, the working medium liquid passes through the pump 24 to the evaporator 21, and the working medium vapor passes to the reflux pipe 18.

The reflux pipe 18 communicates with the working medium inlet 14 of the condenser 11, and allows the working medium vapor from the gas-liquid separator 16 to be returned to the condenser 11 together with the working medium vapor discharged from the turbine 22. however,
As mentioned above, from the gas-liquid separator 16 to the pump 2
The working medium liquid circulated to the evaporator 21 and the turbine 22 in step 4 contains the initial condensate and a solution having a concentration lower than the optimum concentration ξl, so that the overall concentration is lower than the optimum concentration ξl. Naturally, therefore, the concentration of the working medium vapor circulating from the turbine 22 to the condenser 11 is also lower than the optimum concentration. On the other hand, the concentration of the working medium vapor entering the gas-liquid separator 16 is higher than the optimum concentration ξl. Therefore, the variable aperture 17 is
The amount of working medium vapor that flows back from the gas-liquid separator 16 through the reflux pipe 18 is adjusted, and when it joins with the portion from the turbine 22, it reaches the optimum concentration and is sent to the condenser 1.
This is to make it possible to enter 1. Such concentration adjustment can be easily achieved by controlling the variable aperture 17 by applying ordinary process control techniques.

Effects of the Invention This invention maintains the non-azeotropic mixture in the condenser at an optimum concentration by adjusting the amount of refluxed vapor from the gas-liquid separator, thereby ensuring the desired condensing temperature change. It is possible to provide a condensing device that is effective for non-azeotropic mixtures.
Moreover, since it is a non-azeotropic mixture, it is difficult to avoid the condensate and vapor being mixed together, but according to the present invention, it is possible to prevent the vapor from accumulating in the condenser, so it is expected that the condensing performance will be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of this invention.
FIG. 2 is a vapor-liquid equilibrium diagram of a non-azeotropic mixture, and FIG. 3 is a block diagram of a waste heat recovery device that can utilize the condensing device of the present invention. 11... Condenser, 14... Working medium inlet, 15
...Working medium outlet, 16... Gas-liquid separator, 17...
...Variable throttle, 18... Reflux tube, 19... Booster.

Claims (1)

[Claims] 1. A condenser in which the non-azeotropic mixture to be condensed and cooling water flow in completely opposite flows, a gas-liquid separator connected to the non-azeotropic mixture outlet of the condenser, and a gas-liquid separator connected to the gas phase outlet of the gas-liquid separator. It consists of a reflux pipe leading to the non-azeotropic mixture inlet of the condenser and a variable throttle installed in the middle of the reflux pipe. A condensing device for a non-azeotropic mixture, characterized in that the thermodynamically optimum concentration is maintained.