JPH01142389A - Heat exchanger for high-purity fluid - Google Patents

Abstract

PURPOSE:To increase the speed of fluid around a heat transfer tube and improve heat transmission coefficient by a method wherein a heat transfer tube, connected to a high-purity fluid pipeline system, is arranged in the shape of a coil between an outer tank and an inner tank arranged concentrically and provided with a connecting port to be connected to a heat source pipeline system. CONSTITUTION:High-temperature circulating water enters into the outer tank 2 of a heat exchanger 1 through an inlet port 2a and flows upwardly through an annular space between the outer tank 2 and an inner tank 3 while contacting with a heat transfer tube 4. The circulating water filling the outer tank 2 flows into the inner tank 3 and flows out of the outlet port 3a of the bottom of the inner tank to make circulation. On the other hand, ultra-pure water enters into the heat transfer tube 4 through an inlet port 4a and effects heat exchange between high-temperature circulating water while heated ultra-pure water flows out of an outlet port 4b and is supplied to demanding sites. According to this method, the flow passage of heat medium or circulating water is narrowed by the outer tank 2, the inner tank 3 and the heat transfer tube 4; therefore, a sufficient flow speed may be obtained, a heat transmission coefficient may be improved and the heat exchanger can be miniaturized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat exchanger for high-purity fluids, and in particular, for heat exchange of high-purity fluids such as ultrapure water without reducing its purity. The present invention relates to a high-purity fluid heat exchanger suitable for

[Conventional technology]

Conventionally, as a device for exchanging heat between a heat medium circulating in a heat source piping system and a high-purity fluid such as ultrapure water flowing in a high-purity fluid piping system, a Teflon tube is placed in a tank filled with the heat medium. It was equipped with a coiled heat exchanger tube, and a high purity fluid was made to flow inside the heat exchanger tube. Alternatively, there was also one in which a high-purity fluid was passed through a tank and a heat medium was passed through a heat transfer tube.

[Problem that the invention seeks to solve]

In any of the above devices, since the fluid velocity for measurement cannot be easily increased, the heat transmission coefficient of the entire device is low, and as a result, there is a problem that the heat exchanger becomes large.

The present invention was made in order to solve the problems of the prior art described above, and is a heat exchanger for high-purity fluid that increases the fluid velocity around the heat transfer tube, improves the heat transmission coefficient, and downsizes the heat exchanger. Its purpose is to provide vessels.

[Means for solving problems]

In order to achieve the above objects, the configuration of the high purity fluid heat exchanger according to the present invention is a high purity fluid heat exchanger for exchanging heat between the heat medium in the heat source piping system and the high purity fluid in the high purity fluid piping system. an outer tank having a connection port with the heat source piping system;
An inner tank is provided concentrically with the outer tank and has a connection port with the heat source piping system, and a flow of the heat medium is formed between the outer tank and the inner tank. within the should area.

Heat exchanger tubes connected to the high-purity fluid piping system are arranged in a coil shape.

[Effect]

The operation of the above technical means will be explained using an example in which a heat medium inlet is provided at the bottom of the outer tank and a heat medium outlet is provided at the bottom of the inner tank as connection ports with the heat source piping system.

The heat medium such as water supplied from the heat source piping system enters the heat exchanger through the heat medium inlet at the bottom of the outer tank, and contacts the heat transfer tubes through the ring-shaped space area formed by the outer tank and the inner tank. It accumulates upwards, and when it reaches the top, it flows into the inner tank.
The heat medium returns to the heat source piping system from the heat medium outlet at the bottom of the inner tank and is circulated thereafter.

On the other hand, high-purity fluid such as ultra-pure water enters the heat transfer tube from the high-purity fluid piping system, exchanges heat with the heat medium, and then is supplied to the consumer via the high-purity piping system.

- At this time, the flow path of the heat medium is narrowed by the outer tank, inner tank, and heat transfer tubes, so a sufficient flow rate is obtained, improving the heat transfer coefficient, and as a result, the heat exchanger can be small. It turns out.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a system diagram of a pure water heating device equipped with a pure water heat exchanger according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of the pure water heat exchanger. .

In Figures 1 and 2, 1 is a pure water heat exchanger related to a high purity fluid heat exchanger, 2 is an outer tank constituting the pure water heat exchanger, and 3 is a pure water heat exchanger. This inner tank 3 is arranged in the outer tank 2 concentrically with the outer tank 2. 64 is a heat transfer tube through which ultrapure water related to a high purity fluid flows, The heat transfer tube 4 is a coiled tube made of, for example, Teflon, and is spirally arranged in a ring-shaped space region formed between the outer tank 2 and the inner tank 3. This heat exchanger tube 4
65 is a spacer that secures a space between the outer tank 2 and the inner tank 3 and also serves as a guide plate for the flow path. Multiple units are to be installed on the

6 is a lid provided on the upper part of the outer tank 2, and 7 is an automatic air vent valve provided on the lid 6.

Reference numeral 8 denotes a pure water piping system related to high-purity fluid piping, which is connected to the heat exchanger tube 4 through a surface connection port of a pure water inlet 4a and a pure water outlet 4b.

9 is a piping system for cold water serving as a heat source water.

10 is a compressor that compresses refrigerant gas; 11 is a condenser; 1
2 is an expansion valve; 13 is a water cooler that functions as an evaporator;
14 is a refrigerant pipe line for connecting these devices to form a refrigeration cycle.

Reference numeral 15 denotes a circulating water piping system related to the heat source piping system, in which water is used as the heat medium in this embodiment.

Reference numeral 16 denotes a circulation pump that circulates water in the circulating water piping system as indicated by the solid line arrow. The circulating water piping system 15 is connected to the pure water heat exchanger 1 through the surface connection port of the circulating water flow port 2a provided at the bottom of the outer tank 2 and the circulating water outlet 3a provided at the bottom of the inner tank 3. Connected.

Next, the operation of such a pure water heating device will be explained with reference to Figures 1 and 2. In Figure 6, the solid line arrows indicate the flow direction of the circulating water, which is the heat medium, and the broken line arrows indicate the flow direction of the heat source water. The direction of flow of certain cold water, the dashed-dot arrow, indicates the direction of flow of ultrapure water, which is a high-purity fluid.

The high-temperature, high-pressure refrigerant gas discharged from the compressor 10 radiates heat to the circulating water of the circulating water piping system 15 in the condenser 11, and the refrigerant is condensed and liquefied. The low-temperature liquid refrigerant is depressurized through the expansion valve 12 and enters the water cooler 13, where it exchanges heat with the cold water in the cold water piping system 9 and evaporates. The vaporized low-temperature, low-pressure refrigerant gas returns to the compressor 10 and repeats the same cycle.

The high temperature circulating water heated by the condenser 11 has a circulating water flow population 2
It enters the outer tank 2 of the pure water heat exchanger 1 from a, and moves upward through the ring-shaped space area formed between the outer tank 2 and the inner tank 3 while coming into contact with the heat transfer tubes 4. The circulating water that filled the outer tank 2 flows into the inner tank 3, returns to the circulating water piping system 15 from the circulating water flow center opening 3a at the bottom of the inner tank, and is circulated thereafter.

On the other hand, the ultrapure water in the pure water piping system 8 enters the heat transfer tube 4 from the pure water inlet 4a and is heated by exchanging heat with the high temperature circulating water.
The heated ultrapure water is supplied from the pure water outlet 4b to the consumer via the pure water piping system 8.

According to the pure water heat exchanger of this embodiment, the flow path of the circulating water, which is a heat medium, is narrowed by the outer tank 2, the inner tank 3, and the heat transfer tube 4, so that a sufficient flow rate can be obtained, and the heat exchange rate has improved,
As a result, the heat exchanger can be small.

Therefore, the effect of this embodiment will be compared with the conventional technology in terms of the heat transfer coefficient.

Regarding the pure water heat exchanger with an inner tank of this example, the heat transfer tube is made of Teflon, has an outer diameter of 12 mm, an inner diameter of 111 mm, and a tube wall thickness of 0.
．． Using a 5 mm tube, the flow velocity and heat transmission coefficient of circulating water around the heat exchanger tube were measured by experiment.

As a result, the maximum flow velocity U,a, = 0, 26 m/s
Forced convection occurs, resulting in a heat transfer coefficient of 290 kcaQ/m
It was 2h°C.

On the other hand, regarding a conventional pure water heat exchanger without an inner tank, it is equipped with Teflon heat exchanger tubes of the same dimensions as above, and the maximum flow rate and heat exchanger are The penetration rate was estimated with reference to literature data. As for the literature, "Heat Transfer Engineering Materials Revised Third Edition" 2, Japan Society of Mechanical Engineers, published in February 1975 was referred to.

Assuming that the heating medium descends in the tank with a uniform velocity distribution, the maximum flow rate of the circulating water, which is the heating medium, is U-ax = 0
, 042 m/s. However, in reality,
Since the heat exchanger tubes are arranged closely, the area near the heat exchanger tubes becomes dead water, and the above flow rate cannot be expected.

In this case, the flow of circulating water is forced and natural convection, and there is also interference from the wall. In any case, the thermal transmission coefficient must be estimated with reference to data described in literature.

Generally, the heat transmission coefficient is expressed by equation (1).

K = (Ro+ RT+ R50 R1)-1...(
1) Here, Ro: Thermal resistance of the outer surface of the tube RT: Thermal resistance of the tube itself RI: Thermal resistance of the inner surface of the tube R1: Thermal resistance of dirt outside the tube RO=α0″″1 α0: Thermal conductivity of the outer surface of the tube α0: N umλ/d...
(2) Here, λ: Fluid thermal conductivity d: Pipe outer diameter Nu+s: Average Nusselt number From "Heat Transfer Engineering Materials Revised 3rd Edition JP, 37, the average Nusselt number is expressed by equation (3).

Nu*= 0, 53 CGrx-P rt)"'
-(3) Here, G r t a Grashof number Prz Nybrandtl number Calculation is performed by substituting various numerical values of the conditions of the prior art into this equation (3), but since it is complicated, only the results are shown. N□ clause 14 ．．
2, and the above [Heat Transfer Engineering Materials Revised 3rd Edition JP,
39 From Figure 6, the average Nusselt number N ul of the heat exchanger tube group
l' is estimated as follows.

Nun"F Nun
a Q Therefore, from equation (1), it is estimated to be 4170 kcaQ/m"h"c.

Therefore, according to this example, the heat transmission coefficient is improved by about 70% compared to the conventional technology.

In addition to reducing the size of the heat exchanger by improving the heat transmission coefficient,
The embodiment shown in FIG. 2 also has the following effects.

That is, heat exchanger tubes in the area where they come into contact with the heat transfer medium.

Because there are no joints, there is no risk of the heat medium water getting mixed with the high-purity fluid ultrapure water, and the heat exchanger tubes are arranged in a spiral, so when discharging the liquid inside the heat exchanger tubes, It can also be done smoothly.

Furthermore, the inner tank 3 is filled with warm circulating water and functions as a heat storage tank.

In addition, in the above embodiment, an example of a pure water heating device equipped with a pure water heat exchanger was explained, but the present invention is not limited to this, and the pure water heat exchanger can be applied to a pure water cooling device. Needless to say, it is okay to do so.

Furthermore, in the pure water heating device described above, the heat medium in the heat source piping system is heated in the condenser section of the refrigeration cycle, but it goes without saying that a heat storage tank may also be installed in the heat source piping system. .

Furthermore, in the pure water heat exchanger shown in Fig. 2, the heat exchanger tubes are shown as single tubes arranged in a spiral shape, but the pure water inflow,
There is no problem even if a header is provided at the outlet and the heat transfer tubes are arranged in a plurality of tube groups in a spiral shape.

Further, in the above-mentioned embodiments, an example of a heat exchanger for pure water was explained, but the present invention is not limited to this, and can be applied to heating, cooling, etc. of other high-purity fluids. be.

Further, in the above embodiment, as shown in FIG. 2, the circulating water flow 2a is provided at the bottom of the outer tank 2, and the inner 4'! Although an example has been described in which the circulating water outlet 3a is provided at the bottom of i3 and the heat medium is circulated as shown by the solid arrow, the present invention is not limited to this. For example, a structure may be constructed in which a circulating water inlet is provided on the inner tank side and a circulating water outlet is provided on the outer tank side, so that the heat medium filling the inner tank flows into the outer tank and exchanges heat with the heat transfer tube through which high-purity water flows. Similar effects are expected.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a heat exchanger for high-purity fluid in which the fluid velocity around the heat transfer tubes is increased, the heat transmission coefficient is improved, and the heat exchanger is downsized.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a pure water heating device equipped with a pure water heat exchanger according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of the pure water heat exchanger. . 1... Heat exchanger for pure water, 2... Outer tank, 2a... Circulating water inlet, 3... Inner tank, 3a... Circulating water outlet,
4... Heat exchanger tube, 4a... Pure water inlet, 4b... Pure water outlet, 8... Pure water piping system, 10... Compressor, 1
1... Condenser, 13... Water cooler, 15... Circulating water piping system, 16... Circulating pump.

Claims (1)

[Claims] 1. A high-purity fluid heat exchanger for exchanging heat between a heat medium in a heat source piping system and a high-purity fluid in a high-purity fluid piping system, which comprises an outer tank having a connection port with the heat source piping system, and the outer tank. an inner tank disposed concentrically within the outer tank and having a connection port with the heat source piping system; 1. A heat exchanger for high-purity fluid, characterized in that heat exchanger tubes connected to the high-purity fluid piping system are arranged in a coil shape within the region.