JPS586305A - Reheater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchanger for heating low-pressure steam with high-pressure steam, and particularly to a reheater for a moisture separation reheating device used in a steam turbine power plant.

In conventional steam turbine equipment in nuclear power plants, moisture is removed from the steam that exits the high-pressure turbine using a moisture separator. After being reheated, it is expanded into a low-pressure turbine, and it becomes possible to increase the heat drop and improve plant efficiency through IJT.

FIG. 1 shows a cross section of a conventional reheater 11, in which the steam to be heated 8 enters from an inlet portion 9 of the F section of the shell 2 and exits from an upper outlet portion 1o. A plurality of holes 4 are provided at one end of the shell 2.
A tube sheet 3 having , the header 5 is composed of a partition plate 6 that divides the inlet and outlet parts in the upper] and '' directions, and the heated steam 7 flows in from the upper part, condenses through the communicating heat transfer tube 1, and is discharged to the outlet part. Ru. The heat exchanger tube 1 has a plurality of tubes arranged in the downward direction, and the heat load differs depending on the temperature distribution in the upper direction of the heated steam 8. In the heat exchanger tube at the bottom, condensed water If the flow becomes relatively large, intermittent flow may occur in the J-type heat exchanger tube 1, causing problems such as destruction of the joint between the deformed tube plate of the heat exchanger tube and the heat exchanger tube. As a countermeasure, by introducing the heated steam 7 for scavenging and discharging it together with the condensate in addition to the amount of condensed water determined by the heat load, unstable flow within the heat exchanger tubes can be eliminated.

However, usually 10 to 10% of the amount of heating steam is used as scavenging steam.
Since it requires a flow rate of 15%, it has the disadvantage of causing a low F of approximately 0.2% in terms of plant efficiency.

An object of the present invention is to provide a reheater that prevents a significant drop in plant efficiency by using the scavenging steam in the reheater and heat transfer tubes to further heat the steam to be heated.

The feature of the present invention is that the header portion of the reheater is
By dividing the heat exchanger tubes into two groups, the first tube group and the second tube group, the heated steam flows through the heated steam into four tube groups.
This reheater is designed to improve blunt efficiency by making the steam pass through the steam twice to reduce the proportion of the steam used for scavenging the heat transfer tubes in the amount of heated steam.

Next, a reheater which is an embodiment of the present invention will be explained with reference to FIG. In the figure, the steam to be heated 14 flows into the inlet portion 17 at the bottom of the outer shell, and although not shown in the figure, moisture is removed by a moisture separator, heated in a reheater, and then heated in the outer shell. It flows out from the upper outlet section 18.

A tube header 9 having a tube sheet 3 having a plurality of holes 4 at one end of the outer shell, and a means for introducing and extracting heated steam 10 on one side of the tube sheet 3.
The header 9 is divided by a partition plate 8 between the header 9 and the tube plate 3 to form first, second, and third headers 5, 6.7 in the vertical direction. .

The first header 5 is provided with an inlet means 15 for the heating steam 10 to flow into, and a plurality of IJ-type heat exchanger tubes are installed in the vertical direction to bring the first header 5 and the second header 6 into communication. 1 to tube plate 3
The steam drain 11 and the scavenging steam condensed in the first pipe group 12 are disposed in the second pipe header 6 and constitute the first pipe group 12.
The condensed water is discharged by an outlet means 16 disposed in the second header 6, and the remaining scavenging steam is discharged from a plurality of outlet means 16, which connects the second header 6 and the third header 7. The heat exchanger tubes 1 arranged in the vertical direction are arranged on the tube sheet 3 to constitute a second tube group 13, and the remaining steam discharged to the second pipe nozzle 6 is transferred to the second tube group 13. Most of the heat is recovered as condensed water and discharged to the third header 7, and the drain 11 is extracted by the outlet means 16 disposed in the third header 7.

According to this embodiment, conventionally, as scavenging steam for heat exchanger tubes,
What used to require a flow rate of 10 to 15% of the amount of heated steam can now be reduced to a flow rate of 1 to 1.5% by setting the ratio of the number of heat transfer tubes in the first tube group 12 and the second tube group 13 to at least 2:1. It becomes possible to reduce the amount.

According to the present invention, the ratio of the scavenging steam amount in the conventional heat exchanger tube was about 10 to 15% of the heating steam needle, but it is now 1.
It is possible to reduce the amount by 1 to about 15%, which has the effect of increasing the plant efficiency by about 0.2% or more.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional moisture separator reheater, and FIG. 2 is a cross-sectional view of a reheater portion of a moisture separator reheater according to an embodiment of the present invention. 1... Heat exchanger tube, 2... Shell, 3... Tube sheet, 4...
Hole, 5...first header, 6...second header, 7...
・Third header, 8... Partition plate, 9... Header, 10
...Heating steam, 11...Drain, 12...First tube group, 13...Second tube group, 14...Heated steam, 15
... Entrance means, 16... Outlet means, 17... Inlet part, 18... Outlet part. Agent Patent Attorney Akio Takahashi

Claims (1)

[Scope of Claims] 1. In a reheater that applies heat from heated steam that changes from steam to liquid via heat transfer tubes to the steam to be heated and raises the temperature of the steam, a shell, a first tube group, and a second tube group are used. By installing a partition plate on the header divided between the tube group and the tube sheet on which the J-type heat exchanger tubes are attached, the header is divided into three sections, each with a first section. Second. A third header is formed, and one end of the U-shaped heat exchanger tube of the first tube group that guides the heated steam that has flowed into the first header is communicated with the second header located at the center. A person who communicates one end of the U-shaped heat exchanger tubes of a second tube group to guide the heated steam flowing down through the heat exchanger tubes of the first tube group to the third header, and introduces the heated steam to the first header [- ] At the same time, the third header is provided with an outlet means for discharging the heated fluid after heat exchange, and the second header is also provided with a drain discharge means for discharging condensed condensate. A reheater, characterized by: 2. The reheating method according to claim 1, characterized in that the number of heat exchanger tubes in the first tube group is about 2 degrees north of the number of heat exchanger tubes in the second tube group. vessel,.