JPH08219406A - Sheel and tube heat-exchanger for condensing steam - Google Patents

Abstract

PURPOSE: To prevent erosion from occurring, by impinging of condensed waterdrops against a horizontal partition dividing a subcooling zone, in a shell and tube heat-exchanger for condensing steam. CONSTITUTION: A subcooling zone is divided with a partition 7 in a shell 1 in which heat transfer tubes 2 are provided. The subcooling zone is so composed that weirs 8, 9, 10 are provided along the sides of this partition 7, and that a small amount of water is stored in the upper surface of the partition 7. In the case where waterdrops produced by the condensation of steam fall on the upper surface of the partion 7, the waterdrops collide with the film of the water accumulated on the partition 7, scatter the water in the vicinity of the surface of the film, enter the inside of the film, and decelerate when they collide with the partition 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shell and tube heat exchanger for condensing and heating steam, such as a low pressure heater in a thermal power plant or a nuclear power plant.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show sectional views of a conventional low-pressure heater. As shown in FIGS. 4 and 5, this low-pressure heater is a shroud-and-tube heat exchanger in which a large number of heat transfer tubes 2 are incorporated in a body 1. The low temperature side fluid flows in from the low temperature side inlet 3, flows in the heat transfer tube 2 and flows out from the low temperature side outlet 4.

Steam as the high temperature side fluid flows in from the steam inlet 5, is cooled and condensed in the heat transfer tube 2, and the condensed water flows into the subcool zone constituted by the partition plate 7 and the condensed water outlet 6
Drained from. 11 is a liquid surface. The steam side pressure is about 1.
5ata, low temperature side inlet temperature is about 70 ° C, low temperature side outlet temperature is about 100 ° C.

[0004]

In such a heat exchanger, conventionally, as shown in FIG. 6 showing the details of the portion A in FIG. 5, condensed droplets may collide with the partition plate 7 to form holes due to erosion. Occurs. With such holes, steam flows in the subcool zone because the condensed water is lower than the saturation temperature, and when the steam disappears in the subcool zone, water hammer pressure is generated and the heat transfer tube 2 may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent erosion from occurring due to condensed liquid droplets colliding with a horizontal partition plate which defines a subcool zone in a steam condensing shell and tube heat exchanger.

[0006]

In order to solve the above-mentioned problems, the present invention adopts a construction in which a weir is provided along the side surface of a partition plate which partitions the subcool zone, and a small amount of liquid is stored on the upper surface of the partition plate. To do.

The height of the weir for accumulating on the upper surface of the partition plate according to the present invention is 5 to 30 mm, preferably about 10 mm.

[0008]

In the heat exchanger according to the present invention, since a small amount of liquid is accumulated by the weir on the upper surface of the partition plate that partitions the subcool zone, when the droplet collides with the partition plate, it collects on the partition plate. When the liquid film collides with the liquid film, the momentum of the droplet is attenuated in the liquid film. Therefore, in the heat exchanger according to the present invention, erosion does not occur in the partition plate that partitions the subcool zone.

[0009]

The steam condensing shell and tube heat exchanger according to the present invention will be specifically described below based on the illustrated embodiments. In the following embodiments, the same components as those of the conventional apparatus shown in FIGS. 4 to 6 are designated by the same reference numerals for the sake of simplicity.

In the heat exchanger shown in FIGS. 1 to 3, weirs (8, 9, 10) are provided above the partition plate 7. As shown in FIG. 3, which shows the details of the part B in FIG. 2, the weir is approximately 20 mm horizontally.
It is extended by ~ 50 mm to make it wider than the partition plate 7. The diameter of the body 1 of this heat exchanger is 1 m, and the height of the weir is 5 to 30.
mm, for example 10 mm, is suitable. Other configurations are shown in FIG.
It is substantially the same as that shown in FIG.

The droplets produced by the condensation of the vapor are estimated to have a diameter of about 100 μm and a velocity of about 30 m / s. When this droplet collides with the partition plate 7, it collides with the liquid film 12 accumulated on the partition plate 7 and scatters the liquid near the surface of the liquid film 12 as shown in detail in FIG. It penetrates into the liquid film 12 and slows down. The relationship between this deceleration and the thickness of the liquid film 12 is expressed by the following equation.

[0012]

[Equation 1]

In this example, Ueo = 30 m / s, d _p = 1 × 10
^-4 m, δ = 5 × 10 ^-3 m, C _D = 0.5, Ue = 2 ×
10 ^-7 m / s, which is the limit of erosion (several m / s
), The partition plate 7 does not cause erosion.

[0014]

As described above, according to the present invention,
By providing a weir along the side surface of the upper partition plate that forms the subcool zone, it is possible to prevent the partition plate from being perforated by erosion due to droplet collision with the partition plate,
It does not damage the heat transfer tube and can contribute to avoiding troubles and improving reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a steam condensing shell and tube heat exchanger according to an embodiment of the present invention.

2 is a sectional view of the heat exchanger of FIG. 1 taken along line II-II.

FIG. 3 is an enlarged cross-sectional view of a portion A in FIG.

FIG. 4 is a cross-sectional view of a conventional vapor condensing shell and tube heat exchanger.

5 is a cross-sectional view of the heat exchanger of FIG. 4 taken along the line VV.

6 is an enlarged cross-sectional view of a portion A in FIG.

[Explanation of symbols]

 1 Body 2 Heat Transfer Tube 3 Low Temperature Side Inlet 4 Low Temperature Side Outlet 5 Steam Inlet 6 Condensed Water Outlet 7 Partition Plate 8, 9, 10 Weir 11 Liquid Level 12 Liquid Film

Claims (1)

[Claims] 1. A steam condensing shell-and-tube heat exchanger in which a subcool zone is partitioned inside by a horizontal partition plate, and a weir is provided along the side surface of the partition plate, and a small amount is provided on the upper surface of the partition plate. A steam condensing shell-and-tube heat exchanger characterized in that it stores the above liquid.