JP2653611B2 - Moisture separation heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture separating and heating apparatus for a nuclear power plant, and more particularly to a moisture separating and heating apparatus for reducing the thermal stress generated in a body of a nuclear power plant and improving the reliability of the apparatus. .

[0002]

2. Description of the Related Art Steam supplied to a steam turbine of a nuclear power plant is wet steam containing a large amount of moisture. The moisture in the steam not only erodes the turbine blades but also increases the steam turbine. Because it reduces efficiency.
It is necessary to separate and remove the moisture in the steam. For this reason, in a nuclear power plant, usually, a moisture separation heating device is provided between a high pressure turbine and a low pressure turbine to remove about 10% of moisture contained in exhaust steam of the high pressure turbine to 1% or less. After the cycle steam is heated to a superheated state, it is supplied to a low-pressure turbine.

FIGS. 3 and 4 show a conventional moisture separating and heating apparatus. Exhaust steam of a high-pressure turbine flows into a main body 1 through a wet steam inlet 2 provided at a lower portion of the main body 1, and is drained. The flow is split right and left on the channel bottom plate 3. The divided wet steam flows in a wet steam distribution chamber 5 formed by a horizontal partition plate 4 that divides the inside of the main body 1 up and down so as to spread in the longitudinal direction of the main body 1, and a pair of vertically arranged wet steams. It flows into the central inner chamber 7 through the separator 6.

[0004] A number of corrugated sheet separating elements (not shown) are juxtaposed in the moisture separator 6, and while passing through these separating elements, moisture is removed to remove steam having low wetness. Become. The low-humidity steam is guided to a steam passage 16 formed by a pair of shrouds 15 vertically arranged in the center of the upper chamber 12 above the horizontal partition plate 4, and the first steam is arranged in the steam passage 16. After being sequentially heated by the stage heater tube bundle 8 and the second stage heater tube bundle 9, the heat flows through the superheated steam duct 10 formed in the upper portion of the main body 1 toward the superheated steam outlet 11 in the longitudinal direction of the main body 1.

The steam flowing out of the superheated steam outlet 11 is guided to a low-pressure turbine (not shown) downstream. The superheated steam duct 10 is fixed only to the shroud 15 and is fitted into a guide groove 13 provided in the upper part of the main body 1, so that the deformation of the main body 1 is not restricted. Also, several balance holes 14 are provided so that the shroud 15 is not crushed from the outside when the steam is suddenly depressurized.

On the other hand, the water droplets removed by the moisture separator 6 flow downward, and the drain passage 17 at the lower portion of the central inner chamber 7 is formed.
It flows into the inside and is discharged outside through a drain outlet 18 provided at the lower part of the main body 1.

[0007]

The flow of steam in a superheated steam duct 10 provided on the upper part of the main body 1 is shown by arrows in FIG. The cycle steam whose temperature has increased through the first-stage heater tube bundle 8 and the second-stage heater tube bundle 9 is
It flows inside the superheated steam duct 10 in the longitudinal direction of the main body 1. FIG. 5 shows the flow rate distribution of the cycle steam. Superheated steam duct 1
Although the flow velocity V in the longitudinal direction within 0 is 0 m / s at both ends A and C, the superheated steam flowing out of the second-stage heater tube bundle 9 gathers as approaching the superheated steam outlet 11 at the center, and the flow velocity V becomes the end. It increases in proportion to the distance from. For this reason, as shown in FIG. 5, the static pressure distribution in the superheated steam duct 10 is maximum at A and C where the longitudinal flow velocity V is 0 m / s, and at the center B
, It decreases in proportion to the square of the flow velocity V.

The pressure in the upper chamber 12 outside the shroud 15 is balanced with that in the superheated steam duct 10 through a balance hole 14 formed in the side surface of the superheated steam duct 10. However, since the static pressure distribution exists in the superheated steam duct 10 as described above, the static pressure in the upper chamber 12 is changed by the pressure change width ΔP in FIG.
Is determined by one of Here, the state of the flow of steam in the upper chamber 12 is shown in FIG.

At both ends A and C of the heated steam duct 10 where the static pressure is high, the heated steam S is jetted into the upper chamber 12, and flows around the central superheated steam outlet 11 where the static pressure is low and flows backward from the upper chamber 12. . That is, the flow in the superheated steam duct 10 is flat.
An effective bypass flow will be formed in the upper chamber 12 . Under such a flow mode, the steam temperature in the upper chamber 12 almost approaches the temperature in the superheated steam duct 10.

FIG. 7 shows a metal temperature distribution of the main body 1.
Since the heat transfer coefficient of the wet steam contact surface in the lower part of the horizontal partition plate 4 which is in contact with the wet steam on the inlet side is high, it is equal to the steam temperature T1 on the inlet side. However, in the upper chamber 12 above the horizontal partition plate 4, the inner surface contacts the steam substantially equal to the superheated steam temperature T2 to exchange heat. For this reason, the metal temperature of the main body body 1 rises rapidly from the portion in contact with the horizontal partition plate 4 and becomes almost equal to the outlet steam temperature T2 in the portion in contact with the superheated steam duct 10.

As described above, since the metal temperature greatly changes in the circumferential direction at the joint portion of the main body 1 with the horizontal partition plate 4, an excessive thermal stress is generated, and there is a possibility that damage occurs at a welded portion between the members. There is.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a moisture separating and heating apparatus which suppresses a sharp temperature gradient from occurring in a main body body, relieves thermal stress, and prevents a welded portion from being damaged. It is in.

[0013]

In order to solve the above-mentioned technical problem, the present invention divides the inside of a main body into an upper chamber and a lower chamber by a partition plate, and the upper chamber is provided with steam in which cycle steam flows to a central portion. A passage is provided, a moisture separator is arranged in the lower chamber, at least one heater tube bundle is arranged in the steam passage, and the moisture of the cycle steam flowing from the steam inlet provided at the bottom of the lower chamber is humidified. After removal by a separator, the steam is heated by a heater tube bundle to take out cycle steam from a steam outlet provided at an upper portion of a steam passage, and furthermore, a pair of shrouds forming a steam passage are provided on a steam outlet side of a main body body in a longitudinal direction. Moisture separation with a superheated steam duct, the upper end of which is movably loosely fitted in a guide groove formed in the inner surface of the main body, and a balance hole formed in the side wall of the superheated steam duct to communicate the upper chamber with the inside of the superheated steam duct. The thermal device and is characterized in that a heat shield plate to form a heat-insulating space along the body cylinder inner surface of the upper chamber.

[0014]

As described above, the temperature in the upper chamber outside of Shurad is substantially equal to the temperature of the heated steam at the outlet of the heater. However, in the present invention, the heat shield plate is provided along the inner surface of the main body, and high-temperature steam does not directly contact the main body. Also,
Between the heat shield plate and the main body cylinder constitute a narrow insulation space spaced, shielding the temperature of the hot plate is increased, does not occur convection in adiabatic space, Den become principal heat transfer by conduction only The amount of heat is reduced.

As described above, since the main body is not heated from the inner surface and the outer surface is insulated by the heat insulating material, the temperature of the main body metal is the heated steam temperature at the upper end and the lower end is the circumferential distance of the inlet steam temperature. The distribution is proportional. Therefore,
In the vicinity of the connection part of the horizontal partition plate, the temperature rise becomes gentle, and the thermal stress is relaxed to prevent the welded part from being damaged.
Can be prevented .

[0016]

An embodiment of the present invention will be described below with reference to FIG. In the configuration shown in this figure, the same components as those of the prior art shown in FIGS. 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 1, the moisture separator 6 and the first and second stage heater tube bundles 8, 9 which are the basic elements of the moisture separating and heating apparatus are arranged in the same manner as in the prior art. , A wet steam distribution chamber 5 , a central inner chamber 7, and a superheated steam duct 10 are respectively arranged.

In this embodiment, in addition to these basic elements, a heat shield plate 2 extends along the inner surface of the main body 1 in contact with the upper chamber 12.
1, a heat insulating space 2 spaced from the main body 1
2 are formed. It is desirable that the width of the heat insulating space 22 is not increased more than necessary. In addition, the heat insulating space 22
The heat shield plate 21 for partitioning is preferably made of a material having a low thermal conductivity.
This is a material such as, for example, austenitic stainless steel. Next, the operation of the above configuration will be described.

The wet steam flows into the main body 1 through a wet steam inlet 2 provided at a lower portion of the cylindrical main body 1, and enters into the wet steam distribution chamber 5 in right and left directions. Here, after the wet steam is distributed in the longitudinal direction of the main body 1, the wet steam changes its flow direction toward the center of the main body 1 and flows into the pair of moisture separators 6. The steam from which the moisture has been removed through the moisture separator 6 is supplied to the central inner chamber 7.
And the upper first-stage heater tube bundle 8 and the second
It passes outside the tube of the stage heater tube bundle 9. At that time, heat exchange occurs with the heated steam in the pipe, the temperature rises, and the steam becomes superheated steam and flows into the superheated steam duct 10 in the upper part of the main body 1. The cycle steam flowing into the superheated steam duct 10 flows toward the superheated steam outlet 11 at the center of the main body 1, and flows out of the main body 1.

Incidentally, the upper chamber 1 outside the Shurad 15
The pressure of 2 is balanced with the inside of the superheated steam duct 10 through a balance hole 14 formed in the side wall of the heated steam duct 10.
From the static pressure distribution in the superheated steam duct 10 described above, superheated steam 15 is ejected toward the upper chamber 12 at the balance holes 14 at the ends A and C of the superheated steam duct, and the upper chamber 12 is discharged at the center B.
The superheated steam flows into the superheated steam duct 10 from the inside.

Due to this steam flow, the steam temperature in the upper chamber 12 becomes almost the same as the superheated steam temperature at the outlet of the second stage heater tube bundle 9, but the steam in the upper chamber 12 follows the inner surface of the main body 1. blocked by the hot plate 21 shield provided Te, it does not flow through the body cylinder 1. That is, a heat insulating space 22 is formed between the two,
There is no direct heating of the inner surface of the main body 1. Insulated space
It is possible to maintain the natural convection inside the insulation space 22 to minimize by reducing the width of 22. Thereby, the heat transfer amount is small, and the main body 1 is in a state in which the inner surface and the outer surface are substantially insulated.

FIG. 2 shows the metal temperature distribution of the main body 1 when the configuration of this embodiment is used. The metal temperature of the main body 1 becomes the outlet steam temperature T2 at a portion where the metal body 1 contacts the superheated steam duct 10 above the inlet steam temperature T1 at the connection with the horizontal partition plate 4, and the temperature rises in proportion to the distance therebetween.

In this manner, the temperature of the body shell metal near the joint with the horizontal partition plate 4 changes gradually, and the thermal stress is reduced, so that the welded portion can be prevented from being damaged.

[0024]

As described above, in the moisture separating and heating apparatus according to the present invention, the heat shield plate for forming the heat insulating space along the inner surface of the main body in contact with the upper chamber outside the shroud and the superheated steam duct is provided. Even when the high-temperature superheated steam flows through the balance hole of the superheated steam duct and the temperature in the upper chamber rises, the main body is not heated from the inner surface. For this reason, the metal temperature of the main body is the inlet steam temperature at the junction between the side of the main body and the horizontal partition, and the outlet steam temperature at the part in contact with the superheated steam duct at the top of the main body, and the middle is proportional to the circumferential distance. As a result, the thermal stress at the junction between the main body and the horizontal partition plate can be reduced, and the reliability of the moisture separating and heating device can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a moisture separating and heating apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a metal temperature distribution of a main body cylinder according to the present invention.

FIG. 3 is a longitudinal sectional view of a conventional moisture separation and heating device.

FIG. 4 is a cross-sectional view of the moisture separating and heating apparatus shown in FIG.

FIG. 5 is an explanatory diagram showing a relationship between a position in a superheated steam duct, a steam flow velocity V, and a static pressure P.

FIG. 6 is an explanatory diagram showing the flow of steam in the upper chamber.

FIG. 7 is an explanatory diagram showing a metal temperature distribution of the main body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body trunk 2 ... Wet steam inlet 4 ... Horizontal partition plate 5 ... Wet steam distribution chamber 6 ... Moisture separator 7 ... Central inner chamber 8 ... First stage Heater tube bundle 9 Second stage heater tube bundle 10 Superheated steam duct 11 Superheated steam outlet 12 Upper chamber 15 Shroud 21 Heat shield plate 22 Thermal insulation space

Claims (1)

(57) [Claims] The interior of a cylindrical main body is divided into an upper chamber and a lower chamber by a partition plate, and a steam passage through which cycle steam flows is provided in a central portion of the upper chamber. A separator is arranged, at least one heater tube bundle is arranged in the steam passage, and after the moisture of the cycle steam flowing from the steam inlet provided at the bottom of the lower chamber is removed by the moisture separator. In order to take out cycle steam from the steam outlet provided above the steam passage by heating with the heater tube bundle, a superheated steam duct in the longitudinal direction of the main body is provided on the steam outlet side of the pair of shrouds forming the steam passage. A moisture separating and heating device having a top end movably loosely fitted into a guide groove formed in the inner surface of the main body, and having a balance hole formed in a side wall of the superheated steam duct to communicate the upper chamber with the superheated steam duct. A heat insulating plate for forming a heat insulating space along the inner surface of the main body in the upper chamber.