JPH0791866A - Heat exchanger - Google Patents

Abstract

PURPOSE:To make it possible to get over difficult points, such as corrosion resistance and heat-exchange with high efficiency by allowing a first fluid having a first specific gravity and a temperature to be circulated respectively as a counterflow with a second fluid whose specific gravity and temperature is different from the first fluid and which is insoluble with the first fluid and heat-exchanging both the first and second fluids. CONSTITUTION:In case when a heat exchanger is adopted for a device, which produces fresh water from marine water based on ice making, marine water taken in from a sea is cooled at a temperature of deg.C at an ice making unit of a refrigerating machine and partially converted into ice while pure water is separated from the other marine water. In the heat exchanger 6, deg.C marine water 3B of high salt content and concentration is heat-exchanged with an intermediate heat medium 10 (fluorine group compound of about 1.8 specific gravity and called as a liquid hereafter). In this heat exchanger 6, the marine water 3B of high salt content and concentration is distributed into a vessel from a nozzle 8 by way of a line 7 while the liquid 10 is adapted to flow in from a nozzle 9 installed at the upper part in the vessel 6. The marine water 3B and the liquid 10 are circulated as a counterflow so that they may be heat-exchanged. Then, the temperature of the marine water 3B in turned to approximately 25 deg.C while the temperature of the liquid 10 is turned to approximately 0 deg. and both the water and liquid are discharged.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat exchanger for exchanging heat energy.

[0002]

2. Description of the Related Art In the food industry, the chemical industry, and the desalination apparatus for seawater as a common example, it is often necessary to efficiently exchange heat between liquids of the same kind having different concentrations. That is, it is an operation of recovering heat (including cold heat) from a liquid whose concentration has been changed by performing a certain kind of heat treatment and applying the heat to an untreated liquid.

In this case, a counter-flow type heat exchanger is usually used, but the heat exchange amount is not sufficiently increased due to the restriction of heat exchange through the heat transfer surface, which causes thermal loss and flow loss of both fluids. It is common sense to accompany.

[0004]

In the prior art, a high-performance heat transfer surface is used to minimize these losses, but it is difficult to say that a sufficient effect is obtained. Further, since the heat exchanger mainly uses metal as a constituent material, there are drawbacks such as a problem of rust and corrosion, an expensive material having corrosion resistance, and a protective treatment. An object of the present invention is to provide a heat exchanger capable of overcoming problems such as corrosion resistance and having a simple structure and high efficiency and heat exchange.

[0005]

The present invention according to claim 1 provides a first fluid having a first specific gravity and a first temperature,
A second fluid which is insoluble in the first fluid and has a second specific gravity larger than the first specific gravity and a second temperature different from the first temperature, and the first fluid are injected from below a predetermined space. The first fluid circulation unit collects the second fluid from above and the second fluid circulation unit injects the second fluid from above the predetermined space and collects it from below.

According to a second aspect of the present invention, a hollow membrane-like member disposed in a predetermined space and airtightly partitioning the predetermined space, a first fluid having a first temperature, and a first fluid And a second fluid having a second temperature different from the above temperature, and the first fluid is injected from below the predetermined space, circulates inside the hollow membrane member, and is recovered from above the predetermined space. And a second fluid circulation unit that injects the second fluid from above the predetermined space, circulates the outside of the hollow membrane-like member, and recovers from below the predetermined space.

[0007]

[Function] With the above configuration, the difficulty of corrosion resistance is overcome,
The heat exchange can be performed with a simple structure and high efficiency.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the heat exchanger according to the present invention is applied to a desalination apparatus for seawater by making ice. Seawater 3 taken from the sea 1 via the water intake line 2 has a water temperature of about 25 ° C. Using the refrigerator 4, the ice-making unit 5 sets the temperature to 0 ° C., and a part of the ice is used to separate pure water from seawater.
The details of the ice making unit 5 are omitted here because they are not related to the present invention. However, when the separation of pure water (ice) from the seawater 3B at 0 ° C. progresses and the salt concentration increases, the separation performance of pure water decreases. Is known. Therefore, it is necessary to continuously introduce new seawater into the ice making unit 5 to continue ice making. The seawater 3B having a high salt concentration discharged from the ice making unit 5 is 0 ° C., and the work of the refrigerator 4 can be reduced if the inflowing seawater 3A having a low salt concentration is cooled as much as possible. The desalination efficiency is also improved. For this purpose, the heat exchanger according to the invention was used. That is, the heat exchanger 6 of FIG. 1 includes the seawater 3B having a high salt concentration of 0 ° C. and the intermediate heat medium (second heat medium) discharged from the ice making unit 5.
Liquid: a fluorine-based compound having a specific gravity of about 1.8 = Fluorinate liquid manufactured by 3M Co., USA) for heat exchange. As shown in FIG. 2, the seawater 3B having a high salt concentration of 0 ° C. discharged from the ice making section 5 flows out from the nozzle 8 inside the heat exchanger 6 into the container via the line 7. (The specific heat of Fluorinert liquid is about 25% of seawater and the specific gravity is about 1.8 times. The specific heat per unit volume is 45% of seawater, and the volume flow rate to make the heat equivalent is about 2.2 times.) The Fluorinert liquid 10 flows in through the nozzle 9 installed in the upper part of the inside. The seawater 3B and the Fluorinert liquid 10 exist as flows in which the traveling directions are opposite to each other, and the relative speed between the two is governed by gravity and the density difference. Inside the container, a honeycomb rectifying plate 11 having an opening area sufficiently larger than the droplet size in the flow direction is installed. The outlet temperature of the high-salinity seawater 3B that has been heat-exchanged in the heat exchanger 6 is approximately 25 ° C, while the temperature of the Fluorinert liquid 10 has decreased to approximately 0 ° C. on the other hand,
The seawater 3A with a low salinity of about 25 ° C collected from the sea 1 flows into the Fluorinert liquid 10 through the nozzle 8 from the lower part of the other heat exchanger 12, and then descends into the Fluorinert liquid 10
It rises due to buoyancy against the flow of. The heat exchange procedure at this time is exactly the same as that of the heat exchanger 6. In the heat exchanger 12, the seawater with a low salinity of about 25 ° C. 3A is cooled to about 0 ° C. and then flows into the ice making section 5 from the line 13 and a part of the ice is converted to a salinity by the action of the refrigerator 4. The seawater 3B that has been enhanced and has a high salinity concentration is discharged toward the heat exchanger 6. In the heat exchanger 12, the Fluorinert liquid 10 is heated from about 0 ° C. to about 25 ° C. and again sent to the heat exchanger 6 via the line 14.

Next, the operation of the embodiment configured as described above will be described. The principle of the present invention is based on the phenomenon that two kinds of liquids having different specific gravities and insoluble in each other float on one and settle on the other. Therefore, the relative velocities of both liquids are almost determined by the combination of the liquids, and the relative velocities cannot be further increased. Therefore, in the present invention, water is representatively selected as one of the liquids, and a non-water-soluble liquid having a high specific gravity of 1.5 or more is selected as the other liquid. As a result, the relative speed between the two can be made relatively large. By the way, the relative velocity between water and Fluorinert is about 0.8 m / s. FIG. 3 is an illustrative view showing the relationship between the area occupied by each other and the velocity in the cross section when the seawater 3 rises as droplets in the Fluorinert liquid 10 which becomes the liquid phase inside the heat exchanger. Fluorinert movement speed V
Since the sum of the absolute value of f and the moving velocity Vw of water is about 0.8 m / s, the processing flow rate per unit area of the heat exchanger cross section is almost constant.

The seawater 3A taken from the sea 1 is initially about 25 ° C.
Although it is a high temperature, it is possible to cool to around 0 ° C. by the cold heat of the 0 ° C. high-salt-concentration seawater 3B discharged from the ice making section 5 by the heat exchanger. In this embodiment, the fate of cold heat of pure water separated as ice is not described, but if the cold heat of ice can also be used to cool the seawater 3A, the inflow temperature to the ice making unit 5 is further reduced to 0. It is possible to approach ℃.

As described above, since the conventional heat exchanger uses, for example, a shell-and-tube heat exchanger mainly made of a metal material for heat exchange between the intake seawater 3A and the discharge seawater 3B, the seawater is particularly used. In the case of the target embodiment, rust and corrosion occur. In the heat exchanger, there is no change in heat transfer performance even if the main structural material is plastic with poor thermal conductivity. Therefore, it is possible to avoid problems such as rust and corrosion. In this way, after the thermal energy is transferred from the first liquid to the second liquid, by the same means, from the second liquid to the final liquid, the third liquid (up to the initial temperature of the first liquid) It is possible to transfer heat energy of the same liquid as the first liquid whose purpose is heating). As a result, heat is transferred from the first liquid, which is in principle incapable of direct contact heat exchange, to the third liquid at an efficiency equivalent to that of direct contact. Thus, by using a heat exchanger, it is possible to extract heat from the first liquid at the target temperature (high or low temperature) and then transfer this heat to the third liquid with extremely high efficiency. Also, the heat exchanger to be used can achieve the purpose by simply using a cylindrical container instead of a high-grade and expensive material such as shell and tube.

As described above, according to the present heat exchanger, in the food industry, chemical industry, seawater desalination, etc., heat exchange of liquids of the same kind having different temperatures such as Fluorinert can be performed by using a heat medium insoluble in these liquids. It is possible by using it, and
The heat exchanger does not transfer heat through a metal partition as in the past, but it is possible to remove the existence of a partition, and since it is almost direct contact heat exchange, dirt, performance deterioration, rust, corrosion etc. of the partition It frees you from the problems that were inevitable until now.

FIG. 4 is a block diagram of a heat exchanger showing another embodiment of the present invention. In the first embodiment, the relative velocities of the two types of liquid inside the heat exchanger are determined by the combination of the liquids.
If the specific gravity difference between the liquids is not sufficient, the relative velocity decreases and heat exchange efficiency decreases. FIG. 4 shows a heat exchanger developed to solve this problem and increase the relative speed. That is, a plurality of headers for flowing a heat exchange liquid having a small volume flow rate are installed above and below the heat exchanger 20, and a plurality of tubes made of a flexible thin film are provided between the headers. It is installed in communication. This embodiment is also incorporated in a seawater desalination apparatus using ice making, as in the first embodiment.

The Fluorinert liquid 10 flows in from the upper part of the heat exchanger 20 at a temperature of 25 ° C., flows around the header 21 and the tube 22, and proceeds downward. On the other hand, seawater 3B at about 0 ° C is a heat exchanger.
The lower header 21A of 20 passes through the inflow tube 22 and flows upward. Even if the flow rate is changed in order to secure the relative speed, it can be dealt with by changing the occupied area of each fluid due to the flexibility of the tube. However, the pumping of the liquid by the pump like the conventional heat exchange technique is meaningless in the present invention, and in principle, the natural levitation and sedimentation are basically used.

Next, another embodiment will be described.
Since the heat is exchanged through the thin film, the heat transfer characteristics are worse than in the case of direct contact. However, since it is a thin film having flexibility, the liquid inside and outside the tube interferes with each other in flow and locally becomes a flow with severe fluctuations. Therefore, in the heat transfer area, it is not possible to secure the extent of direct contact with droplets, but it is possible to prevent the generation of droplets with a small diameter (moving speed is relatively small) as in the case of direct contact. Also,
Even if there is a hole in the thin film and mixing of the internal fluid occurs, it stays at the top and bottom of the heat exchanger 20, so it can be collected and the performance is slightly deteriorated. As described above, also in the present embodiment, the liquid circulation is based on the natural circulation due to the difference in specific gravity, and it is possible to achieve the prevention of over-mixing inside the heat exchanger and the securing of the stability against a slight flow rate ratio variation through the thin film tube. It is possible. Since the flow is due to the density difference between the fluids and no means such as pumping is used,
The pressure difference across the thin film tube is so small that it does not force the membrane to break.

Since it is possible to use plastic or nylon for both the heat exchanger container and the thin film tube, the problem of rust and corrosion due to the use of seawater or the like is extremely small.
It is also noted that the flexible thin film tube is freely deformed and constantly shakes when it is used, so that the adhesion of microorganisms and dirt to the surface is slight.

[0017]

According to the present invention, it is possible to provide a heat exchanger capable of overcoming the problem of corrosion resistance and having a simple structure and highly efficient heat exchange.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an exemplary solution diagram of a heat exchange state inside the heat exchanger shown in FIG.

FIG. 3 is a diagram for explaining the movement of the heat exchange medium of the heat exchanger shown in FIG.

FIG. 4 is a sectional view showing the configuration of a heat exchanger according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Sea 2 ... Water intake line 3 ... Seawater 3A ... Low salinity seawater 3B ... High salinity seawater 4 ... Refrigerator 5 ... Ice making part 6 ... Heat exchanger 7 ... Discharge line 8 ... Nozzle 9 ... Nozzle 10 ... Fluorinert liquid 11 … Baffle plate 12… Heat exchanger 13… Inflow line 14… Fluorinate liquid line 15… Pump with flow rate control function 16… Control device 20… Heat exchanger 21… Header 21A
… Lower header 21B… Upper header 22… Flexible thin film tube

Claims (3)

[Claims] 1. A first having a first specific gravity and a first temperature.
And a second fluid that is insoluble in the first fluid, has a second specific gravity greater than the first specific gravity, and has a second temperature different from the first temperature, and the first fluid in a predetermined space. A first fluid circulation part for injecting from below and recovering from above,
And a second fluid circulation unit for injecting the fluid from above from the predetermined space and recovering it from below. 2. A hollow film-shaped member which is disposed in a predetermined space and airtightly divides the predetermined space, a first fluid having a first temperature, and a second fluid different from the first temperature. A second fluid having a temperature; a first fluid circulation part for injecting the first fluid from below the predetermined space to circulate inside the hollow membrane member and recovering from above the predetermined space;
A second fluid circulation part for injecting the fluid from above the predetermined space, flowing through the outside of the hollow membrane member and recovering from below the predetermined space. 3. A honeycomb member for rectifying the flow of the first and second fluids is arranged in the predetermined space.
The heat exchanger described.