JPH11237005A - Desuperheater for boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desuperheater for a boiler wherein a spray water is prevented from directory hitting a ventury without elongating a nozzle. SOLUTION: A tip end protruding in a steam pipe 1 of a spray nozzle 20 is so cut as to be opened on a lower stream side in stream flow direction, and a lid body 21 comprising a plurality of spray water jetting holes 21a is fitted to the opening. The spray water is jetted diagonally from the spray water jetting holes 21a, which hits a drift A of steam to change its direction to horizontal one, for entering a ventury 3. As a result, a thermal shock due to direct hitting of the spray water to an open edge of the ventury 3 is prevented, for longer life of the ventury 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superheat reducer for a boiler, and more particularly to a structure of a spray nozzle constituting the superheat reducer.

[0002]

2. Description of the Related Art FIG. 4 is a system diagram showing an example of a boiler.

[0003] The boiler includes a furnace wall tube constituting a furnace 11, a primary superheater 12, a suspended superheater 13, and a final superheater 14, and includes a primary superheater 12, a suspended superheater 13, and a final superheater 1.
Numeral 4 is a configuration connected by a steam pipe 1 as a superheater connecting pipe. A superheat reducer 16 is provided in the steam pipe 1 between the primary superheater 12 and the final superheater 14. In this example, the superheat reducer 16 is provided near the downstream side of the primary superheater 12, but may be provided near the upstream side of the final superheater 14 as shown by a two-dot chain line.

A pump 1 is externally connected to a furnace wall tube of the furnace 11.
7 supplies water through a water supply pipe 18. Further, spray water is supplied to the superheat reducer 16 through the superheat reducer water supply pipe 19. In the example of FIG.
Although the water is supplied to the furnace wall tube and the superheat reducer 16, the water supply source may be different.

In such a configuration, the water heated by the combustion gas generated by burning the fuel in the furnace 11 turns into steam and flows downstream in the steam pipe 1. Then, the steam is further heated by the primary superheater 12, the suspended superheater 13, and the final superheater 14, and finally sent to a turbine (not shown).

[0006] In order to always obtain a rated output in the turbine, spray water is injected into the superheat reducer 16 to reduce the steam temperature and adjust it to a predetermined temperature.

FIG. 3 is a simplified configuration diagram of a conventional overheat reducer shown in FIG.

A spray nozzle 2 constituting a superheat reducer 16 is provided in the middle of the steam pipe 1. The tip of the spray nozzle 2 is inserted into the steam pipe 1 at right angles to the steam flow direction (axial direction of the steam pipe 1) from above the steam pipe 1 in the figure, and the tip facing the inside of the steam pipe 1 is closed. Have been.

On the outer periphery near the tip of the spray nozzle 2, there are provided a plurality of spray water injection holes 2a which open toward the downstream side in the steam flow direction. A venturi 3 for stirring and mixing steam and water is provided in the steam pipe 1 near the downstream side of the spray nozzle 2 in the steam flow direction.

In such a configuration, the spray nozzle 2 injects spray water supplied from the outside into the steam pipe 1 from the spray water injection hole 2a. The venturi 3 efficiently agitates and mixes the spray water and steam.

[0011]

In the case of the above-mentioned conventional spray nozzle 2, the spray water which is jetted in parallel to the flow of steam flows between the tip of the spray nozzle 2 and the inner periphery of the steam pipe 1 facing the spray nozzle. Under the effect of the drift A generated between the surfaces, the direction changes obliquely upward in the figure and directly hits the opening edge of the venturi 3. Therefore, the venturi 3 may be damaged by the thermal shock.

In order to solve such a problem,
If the distance between the spray nozzle 2 and the steam pipe 1 shown by the symbol S in the drawing is made small and the drift A is reduced, there is a problem that the nozzle length must be lengthened as a result.

Accordingly, an object of the present invention is to provide a boiler overheat reducer which can prevent spray water from directly hitting a venturi without increasing the nozzle length.

[0014]

In order to achieve the above object, the present invention provides a boiler overheat reducer provided with a spray nozzle for externally spraying spray water into a steam pipe connecting a plurality of superheaters. The inside end of the spray pipe of the spray nozzle inserted into the steam pipe is cut obliquely so as to open toward the downstream in the steam flow direction, and the cut opening surface is obliquely downward toward the downstream in the steam flow direction. A lid having a plurality of spray water injection holes for spraying spray water is attached.

Here, it is preferable that the spray water injection hole is provided obliquely downward at an angle of about 45 degrees with respect to the steam flow direction.

In the present invention, spray water is injected obliquely downward from the spray water injection hole toward the downstream side in the steam flow direction. Therefore, the spray water collides with the drift of the steam toward the center of the steam pipe, and becomes substantially horizontal and enters the venturi, so that the spray water does not directly hit the opening edge of the venturi. Spray water injection hole about 4 to steam flow direction
It is even more convenient to provide the spray water downward at an angle of 5 degrees and spray the spray water obliquely downward at an angle of about 45 degrees toward the steam flow direction.

[0017]

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

FIG. 1 is a partial sectional view of a spray nozzle and its vicinity constituting a superheat reducing device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of the spray nozzle shown in FIG.

As in the case of FIG. 3, in FIG. 1, the tip of the spray nozzle 20 constituting the main part of the desuperheater 16 is inserted into the steam pipe 1 from the direction perpendicular to the axial direction of the steam pipe 1. I have.

The spray nozzle 20 of the present invention is cut obliquely so that the tip inside the steam pipe 1 opens downstream in the steam flow direction. Then, as shown in FIG. 2, the lid 21 is attached to this opening. That is, the opening is closed by the lid 21. The cover 21 has a number of spray holes 21 for spray water spray.
a is formed so that spray water can be sprayed downward and inclining toward the downstream side in the steam flow direction.

Further, as shown in FIG.
The venturi 3 and the throat 22 connected to the venturi 3 are provided in the steam pipe 1 near the downstream side of the zero.

In such a configuration, when the spray water is supplied to the spray nozzle 20 from the water supply pipe 19 for the overheat reducer shown in FIG.
1a is injected into the steam pipe 1, but as described above,
Since the spray water injection hole 21a faces obliquely downward toward the downstream side in the steam flow direction in the figure, the spray water also
As shown by the arrow B, the fuel is injected obliquely downward toward the downstream side in the steam flow direction.

Here, after the steam drift A shown in FIG. 1 passes below the spray nozzle 20, it turns obliquely upward toward the center of the steam pipe 1, and spray water jetted obliquely downward. You will hit. As a result, the vectors of the two flows change, and the spray water turns substantially horizontally and enters the venturi 3, where it is stirred and uniformly mixed with the steam.

Accordingly, spray water is prevented from directly hitting the opening edge of the venturi 3, and damage to the venturi 3 due to thermal shock can be eliminated, and the life of the venturi 3 can be extended.

If the drift A of the steam after passing through the lower part of the spray nozzle 20 changes its direction by about 45 degrees, the lid 2 attached to the tip opening of the spray nozzle 20
1 is provided obliquely downward at an angle of about 45 degrees.
When spray water is sprayed about 45 degrees downward from a, spray water easily enters the venturi 3 horizontally depending on the pressure and amount of the drift A and the pressure and amount of spray water.

Further, by configuring the spray nozzle 20 in this manner, spray water can be horizontally fed into the venturi 3 regardless of the size of the drift A.
It is not necessary to make the spray nozzle 20 longer than necessary and shorten the distance S shown in FIG. Therefore, as a result, the length of the spray nozzle 20 can be reduced.

[0027]

As described above, according to the present invention, the spray water is jetted obliquely downward in the steam flow direction so that the flow direction becomes horizontal by colliding with the drift in consideration of the drift of the steam. Since the nozzle structure is used, the thermal shock of the venturi can be eliminated, and the length of the spray nozzle can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a spray nozzle and its vicinity in a superheat reducer according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the spray nozzle shown in FIG.

FIG. 3 is a simplified configuration diagram of a superheat reducer according to a conventional example.

FIG. 4 is a flowchart showing an example of a boiler system.

[Explanation of symbols]

 Reference Signs List 1 steam pipe 2 spray nozzle 12 primary superheater (superheater) 13 suspended superheater (superheater) 14 final superheater (superheater) 20 spray nozzle 21 lid 21a spray water injection hole

Claims (2)

[Claims] 1. A superheat reducer for a boiler having a spray nozzle for spraying spray water from outside into a steam pipe connecting a plurality of superheaters, wherein a tip inside the steam pipe of the spray nozzle inserted into the steam pipe is provided. A lid body having a plurality of spray water injection holes for spraying spray water obliquely downward toward the steam flow direction downstream side, on the cut open surface, obliquely cutting so as to open toward the steam flow direction downstream side. A boiler overheat reducer characterized by being attached. 2. The overheat reducer of a boiler according to claim 1, wherein the spray water injection holes are provided obliquely downward at an angle of about 45 degrees with respect to the steam flow direction.