JPS6370096A - Duct for heat exchanger - Google Patents

Abstract

PURPOSE:To provide a duct for heat exchangers which is excellent both in the resistance to corrosion and in the mechanical strength by winding spirally a metal wire for bracing on the outer circumferential face of a pipe body made of a specified resin. CONSTITUTION:A metal wire, especially a stainless steel wire, for bracing which has elasticity is wound on the outer circumferential face of a pipe body made of a synthetic resin. For the material of a duct 1 for heat exchangers fluorine resin is used. Because the material is used especially at high tempera ture and high pressure, tetra-fluorine resin (TEF resin) or perfluoroalcoxy resin (PFA resin) which is excellent in heat resistance, resistance to corrosion, and resistance to pollution and, furthermore, has a considerable mechanical strength against internal pressure is preferable. And a metal wire 3 for bracing which is wound on the outer circumferential face of a pipe body 2 made of fluorine resin is not restricted to a particular material but a wire made of stainless steel is preferable in consideration of heat resistance, corrosion resistance and cost.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention has excellent corrosion resistance and can effectively reinforce mechanical strength, particularly mechanical strength against external pressure. Concerning conduits for heat exchangers that are ideal for use under pressure.

[Prior Art] As is well known, metal tubes are generally used as conduits for heat exchangers.

It has the drawbacks of insufficient corrosion resistance and scale adhesion.

On the other hand, if carbon materials are used for heat exchanger conduits, the corrosion resistance will be quite good, but the mechanical strength will not be sufficient, and in addition, the contamination resistance will not be sufficient.
Furthermore, if glass is used for heat exchanger conduits, although the corrosion resistance will be good, the mechanical strength will not be sufficient, and
A problem arises in that a large heat transfer area is required due to poor heat transfer efficiency.

Next, if a fluororesin tube such as Teflon is used for the heat exchanger conduit, it will have good corrosion resistance, but it will not have sufficient mechanical strength and will require a large heat transfer area due to poor heat transfer efficiency. In particular, it has a fatal drawback in that its mechanical strength against external pressure is poor. Therefore, this kind of synthetic resin tube body is used as a conduit for a heat exchanger, and the conduit is connected from the outside of the conduit. In reality, heating with steam or the like is not done at all.

[Problems to be Solved by the Invention] As mentioned above, the present inventor has discovered that although fluororesins such as Teflon resins have superior corrosion resistance required for heat exchanger conduits, they have poor mechanical strength, especially In view of the fact that conduits for heat exchangers lack the performance required due to poor mechanical strength against external pressure, we have developed a means to effectively strengthen the mechanical strength of conduits made of fluororesin against external pressure. Thus, we have succeeded in providing a conduit for a heat exchanger that is excellent in both corrosion resistance and mechanical strength.

[Means for Solving the Problems] The present invention provides a heat exchanger, characterized in that an elastic reinforcing metal wire (3) is spirally wound around the outer peripheral surface of a fluororesin tube (2). This relates to an exchanger conduit (1).

[Function] As mentioned above, when a synthetic resin conduit is used in a heat exchanger, the mechanical strength is not sufficient, but for example, when a perfluoroalkoxy resin (hereinafter referred to as PF or A resin) is used, According to the inventor's experiments regarding the inner diameter of 10
mm, thickness 1mm, and length 1000mm, the inside of the PFA resin pipe body has 3kg/cm2G (143℃
) There is no problem even if steam is applied, and the breaking strength is about 9 kg/
cm2G, and has considerable strength against internal pressure.

On the other hand, if the PFA resin pipe is heated from the outside with steam, the pipe becomes flattened and becomes unusable even with steam of 2 kg/cm2G.

This is because although a perfectly circular tube body is relatively pressure resistant, if the tube body is even slightly deformed by some external action, its strength decreases and the deformation progresses further, creating a vicious cycle. Therefore, the externally heated steam for the PFA resin tube is
The limit is 1.2 kg/am2G (122°C).

Based on the above experimental results of the inventor, if a means to prevent the deformation of synthetic resin conduits is developed, the pressure resistance against external pressure can be considerably increased, and this will further reduce the external pressure, which is a drawback of synthetic resin conduits. It is known that the poor mechanical strength of steel can be overcome.

Next, as a means to prevent deformation of synthetic resin conduits,
It is also possible to bury piano wire, etc. into the synthetic resin wall of the synthetic resin tube, but such a method requires a complicated work process;
This is not possible due to cost considerations unless mass production is adopted. Moreover, such a method requires increasing the wall thickness of the synthetic resin tube, which exposes a fundamental flaw in that the heat transfer efficiency decreases.

The present inventor has discovered that 1. Simply by winding an elastic reinforcing metal wire, particularly a stainless steel wire, around the outer circumferential surface of the synthetic resin tube, the deformation of the synthetic resin tube can be effectively prevented. This discovery led to the completion of the present invention.

In short, according to the present invention, if a reinforcing metal wire with elasticity is spirally wound around the outer circumferential surface of a fluororesin conduit for a heat exchanger, the fluororesin is made of a material that naturally improves corrosion resistance. Furthermore, the reinforcing metal wire wound around the outer circumferential surface of the conduit effectively prevents deformation of the conduit body, and this prevention of deformation is achieved even under external pressure. Due to its structure, it has the effect of dramatically improving the mechanical strength of the steel.

[Example] The material of the heat exchanger conduit (1) according to the present invention is as follows.

Any fluororesin can be used, but considering that it is used under high temperature and high pressure, it has excellent heat resistance, corrosion resistance, and stain resistance, and is highly resistant to internal pressure. Tetrafluoride resin (hereinafter referred to as TE) has mechanical strength.
F resin) or PFA J&I resin is suitable.

In the present invention, the reinforcing metal wire (3) wound around the outer circumferential surface of the fluororesin tube (2) is also not limited, but in consideration of heat resistance, corrosion resistance, and cost, stainless steel wire is used. is suitable.

Specific examples are shown below.

[Example 1] Inner diameter 10 mm, thickness 1 mm, length 1000 mm
1 mm diameter on the outer peripheral surface of the PFA resin tube body.

When a stainless steel wire with an inner diameter of 10 mm and a pitch of 3 mm is wound, it does not deform even if steam of 5 kg/cm2G (158°C) is applied to the outside of the tube. It became clear that it could be used even if it was sprayed with steam (C).

[Example 2] A TEF resin tube was used instead of the PFA resin tube in Example 1, and the rest was the same as Example 1. The effect on vapor pressure was almost the same as in Example 1. It became clear that there was no.

[Effects of the Invention] In the conduit of the present invention, deformation caused by externally heated steam can be extremely effectively prevented, thereby completely overcoming the disadvantage of synthetic resin conduits, which is poor mechanical strength against external pressure. Its industrial applicability is enormous.

That is, being able to increase the heating vapor pressure in the heat exchanger means that the heating temperature can be increased, leading to an increase in the amount of heat transfer per unit area.

For example, in the case of a heat exchanger that heats a liquid at 30°C to 80°C, when comparing cases where the heating temperature is 122°C and 151°C, the logarithmic average temperature difference is 63.8°C and 9°C, respectively.
At 3.8°C, there is an increase of about 50%.

Furthermore, in the case of a heat exchanger that heats a liquid at 80°C to 100°C, when the heating temperature is 122°C and 151°C, the logarithmic average temperature difference is 23.9°C and 54.6°C, respectively. ℃, an increase of approximately 2.3 times.

In addition to the above-mentioned effects, the conduit of the present invention has excellent corrosion resistance as described above, and furthermore, since it is easy to flow the fluid to be heated at high speed, it is possible to have a high heat transfer coefficient inside the pipe. be.

In short, the present invention makes it possible to inexpensively manufacture a heat exchanger with a high overall heat transfer coefficient, excellent corrosion resistance, and a simple structure due to the above-mentioned effects. The industrial applicability is enormous.

[Brief explanation of the drawing]

The drawings are explanatory diagrams showing one embodiment of the present invention. In the drawings, (1) is a heat exchanger conduit, (2) is a fluororesin tube, and (3) is a reinforcing metal wire. Patent applicant Orient Chemical Industry Co., Ltd. Agent Patent attorney Takashi Ito Drawing

Claims (1)

[Scope of Claims] 1. A conduit for a heat exchanger, characterized in that an elastic reinforcing metal wire is spirally wound around the outer peripheral surface of a fluororesin tube. 2. The conduit for a heat exchanger according to claim 1, wherein the fluororesin tube is made of a tetrafluoride resin or a perfluoroalkoxy resin. 3. The conduit for a heat exchanger according to claim 1, wherein the reinforcing metal wire is made of stainless steel.