JPH05203388A - Straight-tube type shell and tube heat exchanger - Google Patents

Abstract

PURPOSE:To improve heat exchanging performance and buckling resistance of a heat transfer tube and to reduce in size a heat exchanger in a straight-tube type shell and tube heat exchanger. CONSTITUTION:Heat transfer tubes 1 arranged in a heat transfer tube bundle 6 are arranged at an irregular interval. The arranging interval of the tubes 1 is set wide at the side of an inner shroud 3 and gradually narrow toward the side of an outer shroud 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a straight tube shell and tube heat exchanger.

[0002]

2. Description of the Related Art An example of prior art relating to a straight pipe shell-and-tube heat exchanger (hereinafter abbreviated as heat exchanger) is shown in FIG.
~ It demonstrates by FIG.

FIG. 7 is a schematic vertical sectional view of a heat exchanger, FIG. 8 is a schematic horizontal sectional view of a bundle of heat transfer tubes, FIG. 9 is an explanatory view of a flow state of primary sodium, and FIG. 10 is a flow rate distribution of primary sodium. Fig. 11 is an explanatory diagram of the corresponding area of primary sodium,
FIG. 12 is an explanatory view of the temperature distribution of the heat transfer tube, where 1 is the heat transfer tube, 2 is the outer shroud, 3 is the inner shroud, 4 is the upper tube plate, 5 is the lower tube plate, 6 is the heat transfer tube bundle portion, and 7 is Entrance window, 8
Is an exit window, 9 is an outer shell, 10 is a primary sodium inlet nozzle, 11 is a secondary upper end plate, 12 is a secondary upper plenum, 13 is a primary sodium outlet nozzle, 14 is a secondary lower plenum, 15 Indicates a secondary sodium inlet pipe, and 16 indicates a secondary sodium outlet nozzle.

In FIG. 7, the outer shell 9 is provided with a primary sodium inlet nozzle 10 and a primary sodium outlet nozzle 13. The secondary-side upper end plate 11 is integrated with the upper tube plate 4, forms a secondary-side upper plenum 12 therein, and has a secondary sodium outlet nozzle 16 in the upper part.

The heat transfer tube bundle 6 is arranged in the annulus space formed by the outer shroud 2 and the inner shroud 3, and its upper end is connected to the upper tube sheet 4 and its lower end is connected to the lower tube sheet 5, respectively. There is. An inlet window 7 is attached to the upper part of the outer shroud 2 and an outlet window 8 is attached to the lower part thereof.

The secondary sodium inlet pipe 15 is installed so as to penetrate through the secondary upper end plate 11, the upper pipe plate 4 and the lower pipe plate 5, and communicates with the secondary lower plenum 14 through the lower end opening. There is.

The primary sodium flows into the outer shell 9 from the primary sodium inlet nozzle 10 and further into the heat transfer tube bundle portion 6 from the inlet window 7. The primary sodium that has flowed into the heat transfer tube bundle 6 flows down outside the heat transfer tube while exchanging heat with secondary sodium that rises inside the heat transfer tube, which will be described later.
It passes through the outlet window 8 and flows out of the outer shell 9 from the primary sodium outlet nozzle 13.

On the other hand, the secondary sodium flows into the outer shell 9 from the secondary sodium inlet pipe 15 to reach the secondary side lower plenum 14, then reverses and flows into the heat transfer pipe.
While rising in the pipe, it exchanges heat with the primary sodium flowing outside the pipe, reaches the secondary upper plenum 12, and flows out of the outer shell 9 from the secondary sodium outlet nozzle 16.

In FIG. 8, the heat transfer tube 1 is a heat transfer tube tube bundle portion 6
Is located on each circumference of several circumferences formed concentrically, and the intervals between the circumferences are the same.

FIG. 9 shows the flow state of the primary sodium flowing down the outside of the heat transfer tube 1 in the heat transfer tube bundle portion 6 having the above-described structure. The downward flow velocity distribution of the primary sodium in the axial direction is as follows, except for the vicinity of the inlet window 7 and the outlet window 8.
It is a constant value.

That is, in the vicinity of the entrance window 7, the entrance window 7
The horizontal flow of the primary sodium flowing from the heat transfer tube into the tube bundle portion 6 hits the heat transfer tube 1 at a right angle, and the inner shroud 3
As it goes to the side, the flow gradually becomes axial.

Further, in the vicinity of the outlet window 8, the primary sodium that has flowed down in the axially downward direction becomes a horizontal outward flow as it approaches the outlet window 8, and the outlet window 8
Immediately before, the heat transfer tube 1 (see FIG. 8) is crossed at a right angle and flows out of the heat transfer tube bundle portion 6 from the outlet window 8. Therefore, in the vicinity of the entrance window 7 and the exit window 8, the flow is complicated.

In order to reduce uneven flow of the heat transfer tube bundle 6, reduce the temperature difference between the heat transfer tubes arranged in the heat transfer tube bundle 6, and improve the soundness of the heat transfer tube against buckling. An example in which a baffle plate is installed near the entrance window 7 and near the exit window 8 is disclosed in JP-A-59-71997.

[0014]

FIG. 10 shows a downward flow velocity distribution of primary sodium in the bundle of heat transfer tubes having a horizontal axis from the position of the inner shroud to the outer shroud in the prior art. Thus, the downward flow velocity distribution of the primary sodium in the axial direction has a constant value. However, as shown in FIG. 9, in the vicinity of the inlet window and the outlet window, the primary sodium retention region increases toward the inner shroud side, and a region that does not contribute to heat exchange appears.

FIG. 11 shows the corresponding area of the primary sodium received by each heat transfer tube. That is, in the case of the arrangement of the heat transfer tubes of the conventional heat exchanger, the corresponding area of the primary sodium received by each heat transfer tube is equal in any heat transfer tube.

FIG. 12 shows the average temperature distribution of the heat transfer tubes in the heat transfer tube bundle portion in such a flow state. In the vicinity of the inlet window and the outlet window, heat is not exchanged very efficiently due to the retention area of the primary sodium on the inner shroud side, and the average temperature of the heat transfer tubes on the inner shroud side is Lower than hot tubes.

Further, the flow of primary sodium flowing from the inlet window to the inner shroud side and the flow from the inner shroud side to the outlet window are at right angles to the heat transfer tubes. Therefore, these flows have better heat exchange efficiency than the flows that are parallel to the heat transfer tubes, and
The average temperature of the heat transfer tubes is higher on the outer shroud side than on the inner shroud side.

That is, since the heat transfer tube bundle has a portion with good heat exchange efficiency and a portion with poor heat exchange efficiency, this deteriorates the heat exchange efficiency of the entire heat exchanger. Further, since the temperature difference between the inner shroud side and the outer shroud side is large, the heat transfer tube on the inner shroud side, which has a relatively low average temperature, tends to contract, and the heat transfer tube on the outer shroud side, which has a relatively high average temperature, Trying to expand.

Therefore, the heat transfer tube on the outer shroud side receives a compressive load, and the soundness of the heat transfer tube against buckling deteriorates. That is, conventionally, there have been two problems: deterioration of heat exchange efficiency and deterioration of soundness against buckling.

A baffle plate is installed to reduce the retention area of the primary sodium so that a cross flow occurs in the primary sodium in the vicinity of the inlet window and the outlet window of the heat transfer tube bundle. A method of making the average temperature of the heat tube uniform is disclosed in Japanese Patent Laid-Open No. 59-71997, but in this case, the pressure loss of the baffle plate becomes large and the structure becomes complicated.

The object of the present invention is to improve the heat exchange efficiency and the soundness against buckling of the heat transfer tube by a simple structure in which the pressure loss of the primary sodium does not increase in the heat exchanger. To provide the structure of.

[0022]

The above object can be achieved as follows.

In a straight shell-and-tube heat exchanger in which heat transfer tubes parallel to the axial direction are arranged, (1) the heat transfer tubes are unevenly spaced so that the average temperature of the heat transfer tubes is uniform. Arrange with.

(2) The arrangement interval of the heat transfer tubes is gradually reduced as the arrangement of the heat transfer tubes approaches from the central portion to the outer peripheral portion.

(3) The inner diameter of the heat transfer tubes is gradually increased as the arrangement of the heat transfer tubes approaches from the central portion to the outer peripheral portion.

[0026]

According to the present invention, the arrangement interval of the heat transfer tubes in the heat transfer tube bundle is widened on the inner shroud side and gradually narrowed toward the outer shroud side. Therefore, in the heat transfer tube on the inner shroud side, the amount of primary sodium that receives heat per unit increases, and the amount of heat exchanged also increases accordingly, so that the average temperature of the heat transfer tube on the inner shroud side increases.

On the other hand, in the heat transfer tube on the outer shroud side, 1
Since the amount of primary sodium received per book decreases, and the amount of heat exchanged accordingly decreases, the average temperature of the heat transfer tubes on the outer shroud side decreases. Therefore, the average temperature of each heat transfer tube can be made uniform.

Even when the heat transfer tubes in the heat transfer tube bundle are arranged at the same interval, the inner diameter of the heat transfer tubes is made smaller on the inner shroud side and gradually increased as they approach the outer shroud side. .. Therefore, although the heat receiving area per heat transfer tube is small on the inner shroud side and large on the outer shroud side, the average temperature of each heat transfer tube can be made uniform as in the case of the above embodiment.

[0029]

Embodiments of the present invention will be described with reference to FIGS.

1 to 5 are drawings relating to one embodiment, FIG. 1 is a schematic cross-sectional view of a bundle of heat transfer tubes, FIG. 2 is an explanatory view of a flow state of primary sodium, and FIG. FIG. 4 is an explanatory diagram of a flow velocity distribution, FIG. 4 is an explanatory diagram of a corresponding area of primary sodium, and FIG. 5 is an explanatory diagram of a temperature distribution of a heat transfer tube. FIG. 6 is a schematic cross-sectional view of a heat transfer tube bundle portion of another embodiment. Note that the reference numerals are the same as those described above, and thus the description thereof will be omitted.

As shown in FIG. 1, in one embodiment, the heat transfer tubes 1 are installed in a non-uniform arrangement, the intervals between the heat transfer tubes 1 are widened on the inner shroud 3 side, and the outer shroud 2 is arranged.
It gradually narrows as it gets closer to the side.

The flow condition of the primary sodium in this example is shown in FIG. From the inlet window 7 to the heat transfer tube bundle 6
The primary sodium flowing into the core flows downward in the axial direction. FIG. 3 shows the axial downward flow velocity distribution of the primary sodium in the heat transfer tube bundle portion 6 excluding the vicinity of the inlet window 7 and the vicinity of the outlet window 8 at this time.

That is, since the arrangement intervals of the heat transfer tubes on the inner shroud side are wide and the resistance due to the friction of the tubes of the heat transfer tubes is not so much received, the axial downward flow velocity on the inner shroud side is high. On the other hand, the arrangement interval of the heat transfer tubes on the outer shroud side is narrow, and a large amount of resistance due to the friction of the heat transfer tubes is received, so the flow velocity in the axial downward direction becomes slow.

FIG. 4 shows the corresponding area of the primary sodium received by each heat transfer tube 1. In the case of this embodiment, the corresponding area is larger on the inner shroud side and smaller on the outer shroud side.

As described above, on the inner shroud side, the corresponding area of the primary sodium received by each heat transfer tube 1 is large, and the flow rate of the primary sodium is high, so that it is relatively from the primary sodium side. The amount of heat received increases, and as a result, the average temperature of the heat transfer tubes on the inner shroud side rises.

On the other hand, on the outer shroud side, the amount of primary sodium received by each heat transfer tube decreases, and the flow rate of the primary sodium decreases, so that the average temperature of the heat transfer tube decreases. It will be.

That is, conventionally, in the vicinity of the inlet window and the outlet window, heat is not exchanged very efficiently due to the retention of the primary sodium on the inner shroud side, which is the average temperature of the heat transfer tubes on the inner shroud side. It had a great impact on the decline.

However, in this embodiment, the heat exchange amount of the heat transfer pipes on the inner shroud side is increased and the heat exchange amount of the heat transfer pipes on the outer shroud side is reduced except for the vicinity of the inlet window and the vicinity of the outlet window. As a result, the average temperature of each heat transfer tube in the heat transfer tube bundle can be made uniform. FIG. 5 shows the temperature distribution of the heat transfer tube in this embodiment.

FIG. 6 shows the case of another embodiment. In this case, the arrangement intervals of the heat transfer tubes are the same on the inner shroud 3 side and the outer shroud 2 side.

However, in this embodiment, the diameter of the heat transfer tube 1 is smaller on the inner shroud 3 side and larger on the outer shroud 2 side. Therefore, the relative heat receiving area of the primary sodium per heat transfer tube 1 is large on the inner shroud 3 side and small on the outer shroud 2 side.
Since the flow rate of the next sodium is high on the inner shroud 3 side and slow on the outer shroud 2 side, the average temperature of each heat transfer tube 1 of the heat transfer tube bundle portion 6 is made uniform as in the case of the above-mentioned embodiment. be able to.

[0041]

According to the present invention, using a simple structure,
The average temperature of each heat transfer tube can be made uniform without increasing the pressure loss, and the heat exchange efficiency of the heat exchanger can be improved.

Further, the soundness of the heat transfer tube against buckling is improved, and the heat exchanger tube can be downsized by reducing the thickness of the heat transfer tube.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of an embodiment of the present invention.

FIG. 5 is an explanatory diagram of an example of the present invention.

FIG. 6 is a schematic cross-sectional view of another embodiment of the present invention.

FIG. 7 is a schematic vertical sectional view of a conventional example.

FIG. 8 is a schematic cross-sectional view of a conventional example.

FIG. 9 is an explanatory diagram of a conventional example.

FIG. 10 is an explanatory diagram of a conventional example.

FIG. 11 is an explanatory diagram of a conventional example.

FIG. 12 is an explanatory diagram of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heat transfer tube, 2 ... External shroud, 3 ... Internal shroud, 4 ... Upper tube plate, 5 ... Lower tube plate, 6 ... Heat transfer tube bundle part, 7 ...
Inlet window, 8 ... Outlet window, 9 ... Outer shell, 10 ... Primary sodium inlet nozzle, 13 ... Primary sodium outlet nozzle.

Claims (3)

[Claims] 1. A straight-tube shell-and-tube heat exchanger in which heat transfer tubes parallel to the axial direction are arranged inside, the heat transfer tubes are arranged at unequal intervals, and the average temperature of the heat transfer tubes is made uniform. A straight-tube shell-and-tube heat exchanger characterized in that 2. A straight-tube shell-and-tube heat exchanger in which heat transfer tubes parallel to the axial direction are arranged inside, as the arrangement of the heat transfer tubes approaches from the central part to the outer peripheral part,
A straight-tube shell-and-tube heat exchanger, characterized in that the arrangement intervals of the heat transfer tubes are gradually reduced. 3. A straight-tube shell-and-tube heat exchanger in which heat transfer tubes parallel to the axial direction are arranged inside, as the arrangement of the heat transfer tubes approaches from the central part to the outer peripheral part,
A straight-tube shell-and-tube heat exchanger characterized in that the inner diameter of the heat transfer tube is gradually increased.