JPH11311401A - Shell-and-tube heat exchanger type horizontal steam generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a heat exchanging efficiency in a shell-and-tube heat exchanger type horizontal steam generator. SOLUTION: A shell-and-tube heat exchanger type steam generator 30 is provided with an outer shell 31, extended into horizontal direction, a heat transfer tube group, consisting of a plurality of heat transfer tubes 43, arranged in the outer shell 31 and through the inside of which high-temperature heating medium is conducted to flow, and a steam separator, arranged in the ceiling unit in the outer shell 31, while partitioning plates 45, 47 are provided so as to surround a cold leg tube group formed of the cold leg 43b of the heat transfer tubes 43 and form an economizer unit 49.

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 type heat exchanger type steam generator, and more particularly to a horizontal steam generator in which a group of heat transfer tubes extends in a horizontal direction and a high-temperature heating medium flows inside the heat transfer tubes. About.

[0002]

2. Description of the Related Art At the present time, in a pressurized water reactor widely used for power generation, a vertical steam generator is generally used, but a horizontal or horizontal steam generator has also been proposed. The structure of this horizontal steam generator will be described with reference to the conceptual diagram of FIG. 4. A large number of U-shaped heat transfer tubes 3 (only one is shown) are provided in a horizontally long outer shell 1 so as to extend in the horizontal direction. And both ends thereof are fixedly supported by the tube sheet 5, and the inlet water chamber 7 and the outlet water chamber 9
Are in communication with each other. Then, the reactor coolant 11, which is a high-temperature heating medium, flows into the heat transfer tube 3 from the inlet water chamber 7, flows through the heat transfer tube 3, reaches the outlet water chamber 9, and returns to the reactor therefrom. At that time, the water supply in the body-side space 13 outside the heat transfer tube 3 is heated and turned into steam.

The movement of the water supply in the horizontal steam generator described above will be described with reference to a conceptual sectional view of FIG. 5. A heat transfer tube group 15 composed of a number of heat transfer tubes 3 is located at the center in the outer shell 1. This heats the water supply in the body-side space 13. The feedwater, which is heated and gradually increased in temperature, flows upward, and partly becomes steam bubbles on the way, and reaches the liquid surface 17 as a gas-liquid two-phase flow.
Then, the steam flows into the steam separator 19 with a large amount of liquid, where the liquid is separated, and the steam 21 travels to a steam-using device such as a steam turbine. The liquid separated by the steam separator 19 becomes circulating water 23 and falls into the water supply.
Further, it flows down between the inner surface of the outer shell 1 and the downcomer plate 25, and flows again into the heat transfer tube group 15 from the bottom. As for the water supply in the trunk side space 13, the above-mentioned flow is repeated during the operation, and the water corresponding to the amount of the steam 21 flowing out is supplied as the water supply 27.

[0004]

However, in the above-described horizontal steam generator having the conventional structure, the circulating water and the newly supplied low-temperature feed water are immediately mixed, and the temperature in the body side space is averaged. Accordingly, the temperature difference between the heat transfer tube and the heating medium in the heat transfer tube becomes smaller on average. Therefore, the heat transfer amount is relatively small, and the heat exchange efficiency is low. Accordingly, an object of the present invention is to provide a shell-and-tube heat exchanger type horizontal steam generator having high heat exchange efficiency.

[0005]

According to the present invention, a horizontal steam generator having a shell-and-tube heat exchanger is provided. A heat transfer tube group including a plurality of heat transfer tubes disposed therein and through which a high-temperature heating medium flows, and a steam separator disposed on a ceiling portion of the outer shell, and further heating the heat transfer tube group. The low-temperature side end from which the medium flows out is surrounded by the separating plate to define an economizer section.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual plan sectional view of a horizontal steam generator 30 according to the present invention, in which a tube plate 33 is integrally formed at one end of a cylindrical outer shell 31 and further adjacent to the tube plate 33. The inlet water chamber 35 and the outlet water chamber 37 are defined by a hemispherical shell-shaped end plate 39. The inlet water chamber 35 and the outlet water chamber 37 separated by the partition wall 41 are connected to a high-temperature heating medium supply source, for example, a pressurized water reactor, via piping not shown. A plurality of heat transfer tubes 43, only one of which is shown in the drawing, for the sake of simplicity of the drawing, form a heat transfer tube group as will be described later. And is open to the inlet water chamber 35. On the other hand, the low-temperature side end of the U-shaped heat transfer tube 43, that is, the cold leg 43b is supported by the tube sheet 33,
The outlet water chamber 37 is open. And a plurality of heat transfer tubes 4
A pair of longitudinal partition plates 45 and a radial partition plate 47 are provided around the third cold leg 43b to form an economizer section 49. As described above, the inner space 51 of the outer shell 31 has a circulation area 51a through which the circulating water flows as described later.
And an economizer section 49 through which new water flows. And a high-temperature heating medium 53 such as a reactor coolant.
Firstly enters the inlet water chamber 35, from which a number of heat transfer tubes 43
And flows through the inside of the
From there, return to the heating medium supply.

Next, a vertical sectional structure of the horizontal steam generator 30 will be described with reference to FIG. The heat transfer tube group 55 formed by the plurality of heat transfer tubes 43 has a hot leg tube group 5 near the tube plate 33.
5a and a cold leg tube group 55b. Since these heat transfer tube groups 55 are formed from the heat transfer tubes 43 arranged in a rectangular shape in a vertical cross section, it should be understood that a liquid can flow though not shown. And
A radial partition plate 47 is provided between the hot leg tube group 55a and the cold leg tube group 55b.
Downcomer plates 57a and 57b are respectively suspended from radially outer ends of the cold leg tube group 55b and the cold leg tube group 55b. A downcomer space 59 in which circulating water descends is formed between the downcomer plate 57a on the side of the hot leg tube group 55a and the outer trunk 31 as described later. Although not illustrated, such a downcomer space 59 is formed along the heat transfer tube group 55 except for the cold leg tube group 55b. On the other hand, the space between the downcomer plate 57b facing the cold leg tube group 55b and the outer shell 31 functions as a lowering space 61 for low-temperature water supply as described later, and the upper part thereof is closed by the downcomer upper plate 63. I have. The downcomer upper plate 63, the downcomer plates 57a and 57b, and the heat transfer tube group 55 are all below the liquid level 65 of the internal feedwater, while the brackish water separator 67 is disposed on the ceiling above it. I have.

As described above, the high-temperature heating medium is a heat transfer tube 4
3, but the feedwater, which is the body-side fluid, flows as follows. That is, in FIG.
9 flows into the descending space 61, and the downcomer plate 57b
Then, it is guided by the partition plate 45 and flows downward as it is, and is inverted at the bottom and enters the cold leg tube group 55b. The water supply 69 rises while being heated in the cold leg tube group 55b,
There is also a portion that is partially boiled and turns into steam, but most of it remains liquid and flows over the upper ends of the partition plates 45 and 47 to the side. In the hot-leg tube group 55a, the feedwater is saturated water, which is heated and rises, and a considerable part of the feedwater is boiled and turned into steam. These vapors rise from the liquid level 65 to the steam separator 67. This vapor stream contains many liquid components, which are separated by the steam separator 67 and returned downward as circulating water 71. The circulating water 71 descends in the downcomer space 59 as shown by the arrow, and is inverted at the bottom and flows into the lower part of the hot leg tube group 55a. Then, it is heated while rising again, and a part is boiled to become steam. The above-described circulation of the water supply is repeated during the operation of the steam generator 30. The dried steam 73 from which the liquid component has been removed in the steam separator 67 flows out to an appropriate steam-using device.

The change in the average temperature of the heating medium inside the heat transfer tube 43 in the operation state as described above
FIG. 3 shows a change in the temperature of the body-side fluid composed of the water supply outside 3. (A) shows the temperature change in the embodiment, wherein line A is the fluid temperature in the heat transfer tube 43, and line B is the heat transfer tube 43.
Indicates the outside fluid temperature. (B) shows the temperature change in the corresponding horizontal steam generator of the conventional structure, wherein line a shows the fluid temperature inside the heat transfer tube 3 and line b shows the fluid temperature outside the heat transfer tube 3.
Since the heat exchange amount between the heating medium and the feedwater in the heat transfer tube is represented by the following equation, the heat exchange amount of the steam generator 30 according to the embodiment of the present invention may be larger. I understand. Amount of heat exchange Q = k · ΔT · A, where k: overall heat transfer coefficient ΔT:
Temperature difference A between the fluid inside the pipe and the fluid outside the pipe A: Transmission area

[0010]

As described above, according to the present invention,
An economizer section is defined around the low temperature side end of the heat transfer tube group of the shell and tube heat exchanger type horizontal steam generator,
Since the low-temperature feedwater is preheated here, the heat exchange efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a plan sectional view conceptually showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along line II-II of FIG.

FIG. 3 is a graph showing the operation and effect of the embodiment compared to a conventional one.

FIG. 4 is a plan sectional view conceptually showing a conventional horizontal steam generator.

FIG. 5 is an elevational sectional view corresponding to FIG. 4;

[Explanation of symbols]

 Reference Signs List 30 steam generator 31 outer shell 33 tube plate 35 inlet water chamber 37 outlet water chamber 39 end plate 41 partition wall 43 heat transfer tube 43a hot leg 43b cold leg 45, 47 partition plate 49 economizer section 51 internal space 51a circulation area 53 heating medium 55 heat transfer tube group 55a Hot leg tube group 55b Cold leg tube group 57a, 57b Downcomer plate 59 Downcomer space 61 Downward space 63 Downcomer upper plate 65 Liquid level 67 Gas-water separator 69 Feed water 71 Circulating water 73 Steam

Claims (2)

[Claims] 1. A heat transfer tube group including a horizontally extending outer shell, a plurality of heat transfer tubes disposed in the outer shell, through which a high-temperature heating medium flows, and disposed on a ceiling in the outer shell. In the shell and tube type heat exchanger type horizontal steam generator having a separated water separator, the separated water circulation region returned from the steam separator and the supply water supply region supplied from the outside are introduced. A shell-and-tube type heat exchanger type horizontal steam generator, wherein a separator is provided. 2. The shell and tube heat exchanger according to claim 1, wherein an end of the heat transfer tube group on the outflow side of the heating medium is surrounded by the separating plate to define an economizer section. Horizontal steam generator.