JPS6215670Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a finned tube used in an open rack type evaporator for vaporizing liquefied refrigerant, such as a heat exchanger.

The open rack evaporator is a device that vaporizes liquefied natural gas using seawater as a heat source,
Liquefied natural gas is primarily transported by sea;
In addition, considering the location of the gasification equipment, it is an evaporation equipment that is widely used because it can use seawater as a heat source, is economical, and is easy to maintain.

Generally, in order to increase the efficiency of heat exchangers, etc.
It is effective to increase the surface area of the tube, and various shapes of finned tubes have been devised, and inserts of various shapes are tightly attached inside the tube for the purpose of increasing the contact area of the medium within the tube. Inserted tubes have also been proposed.

This design uses the fin shape on the outer surface of the tube, the small irregularities on the inner surface, and the shape of the member inserted into the inner surface to exchange heat with higher efficiency than conventional ones. The present invention proposes a tube whose surface can be easily treated after being used as a replacement panel.

The tube according to this invention is a finned tube with multiple fins of any desired protruding height radially protruding from its outer periphery. A number of these finned tubes are arranged in parallel on the same plane, for example the same vertical plane, and one fin of each adjacent tube is brought into contact with each other in the same vertical plane to form a curtain-like panel of finned tubes, which serves as a heat exchanger. In this case, the fins on both sides of the abutting fins of each adjacent tube are made to have a lower protruding height than the abutting fin. That is, for example, in FIG. 1, finned tube 1 is
When the tubes 2 and 3 are arranged in parallel, the long fins 3 and 4 of each tube come into contact with each other, and short fins 5 and 6 are provided on both sides of each tube, and the protruding height of the short fins 5 and 6 is set lower than that of the long fins 3 and 4.
In this case, the distance between the fin apexes, i.e., the opening of the fins to the space formed by the abutment of the long fins 3 and 4, can be made wide.

Next, a rod member 7 (hereinafter referred to as a spiral rod), which is a rod member having radially protruding fins 8 and twisted into a spiral shape, is inserted into the finned tube as described above. This has a higher internal heat transfer coefficient than the conventional spiral tape insert material, which is a spiral tape made from a long and thin plate member, and increases the pressure loss when the coolant passes through the tube. Unbalanced flow of the medium within each tube during panel formation can be reduced.

Furthermore, a large number of small uneven portions 9 are provided on the inner circumferential surface of the tube in the longitudinal direction (second
Figure) increases the contact area of the passing medium with the tube, increasing the heat exchange rate.

A case will be described in which an open rack type evaporator is constructed using the tubes according to the invention described above.

A plurality of aluminum tubes having the shape and structure according to the above-described invention are arranged in parallel on the same vertical plane, and the upper and lower ends of each tube are fitted and fixed into the holes of the upper and lower header tanks to form an evaporator panel. Here, seawater is used as a heat source, and the seawater is supplied from a sprinkler pipe located above the upper header tank. The seawater sprayed from the sprinkler pipes falls along the surface of the fins of each tube and is collected in a water tank located directly below the header tank at the bottom.

In the above evaporator, for example, when liquefied natural gas is sent from the lower header tank to the passages in each tube, it receives heat from the seawater falling on the tube surface and begins to evaporate, and as it rises inside the tube, its temperature increases due to the heat received from the seawater. At the upper end of the rising tube, the gas finally becomes completely room temperature and is sent out from the upper header tank.

By configuring the heat exchange section of the open rack evaporator that operates in this way using the tubes according to this invention, the surface area of the heat exchange section can be
The surface area of the fins protruding from the tube is increased, and the effective heat transfer area is larger than that of the conventional tube heat exchange section.

In addition, because this outer surface area is large, even if the amount of seawater flowing on the outer surface is increased, the seawater does not peel off from the tube surface and a uniform water film can be maintained. It has become possible to greatly increase the heat exchange rate.

Furthermore, as mentioned above, the insertion of the spiral rod 7 into the tube and the small unevenness 9 on the inner peripheral surface of the tube are performed.
This is accompanied by an improvement in the internal heat exchange rate. In addition, if parts are simply inserted tightly into the tube to increase the heat exchange rate on the inside, a lot of ice will form on the outer surface of the tube because the tube wall temperature will approach the temperature of the liquefied gas inside the tube. As the thickness of the ice layer increases, the heat exchange efficiency due to the thermal resistance of the ice decreases. However, in the case of this invention, since the tube is a finned tube with a high heat exchange coefficient on the outer surface of the tube, the above-mentioned ice formation is less likely to occur and the high heat exchange rate between the inside and outside of the tube can be fully utilized.

Next, panels formed by the above-mentioned finned tubes are usually coated with a thermal sprayed zinc alloy to prevent corrosion by seawater. This is done by spraying the alloy from directions B and C in FIG. Therefore, in the case of a tube having a large number of protruding fins, thermal spraying of the alloy cannot be carried out satisfactorily because the fins become an obstacle, and the corrosion resistance of the tube may be poor.

In the panel according to this invention, as described above, an opening from the A direction or an opening from the thermal spraying direction is formed in the space surrounded by the fin that the tube abuts and the low-height fins on both sides of the fin. Since the space is wide, a sufficient amount of zinc alloy can be thermally sprayed on the inner surface of the fin in the space, and the required coating layer thickness can be easily obtained and excellent corrosion resistance can be expected.

For the same reason, since a wide opening can be obtained for water sprinkling from direction A, a sufficient water film can be formed on the inner surface of the space, and heat exchange can be made effective. Therefore, the protruding height of the short fins of this tube is set to a height necessary to sufficiently perform the above-mentioned thermal spraying and improve the heat exchange efficiency.

As mentioned above, this invention reduces the protruding height of the fins arranged on both sides of the abutting fins of the finned tubes arranged in parallel.
Metallicon coating for corrosion protection can be thermally sprayed to a sufficient thickness over the entire surface including the base of the fin, which significantly improves corrosion resistance and extends life.Also, a sufficient film of heated fluid can be formed on the tube surface. The spiral rod inserted into the tube has many fins formed in a star shape, and the pitch of the fins is small, so the turbulence effect is significantly improved compared to the conventional buttful plate formed by twisting flat strip plates. , heat exchange efficiency can be increased.
Therefore, compared to conventional devices, the amount of heating fluid used, the amount of power used, and the area of the device can be reduced, and the device can be made more compact.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of this invention, and FIG. 2 is a cross-sectional view of FIG. 1. In the figure, 1, 2...tube, 3, 4...long fin, 5, 6...short fin, 7...spiral rod,
8... Fin, 9... Uneven part.

Claims (1)

[Scope of utility model registration request] In an open rack type evaporator, fins with a protruding height lower than the protruding height of the abutting fins are provided on both sides of the fins that abut on the same vertical plane of adjacent tubes, and the inner peripheral surface of the tube has many small irregularities. A liquefied gas vaporization device comprising a finned tube in which a rod member having spiral star-shaped fins on the outer peripheral surface is inserted into the tube.