Nozzle chamber warming-up structure for a steam turbine

Details Nozzle chamber warming-up structure for a steam turbine Nozzle chamber warming-up structure for a steam turbine

1999-10-28

2001-11-27

Look, Edward K. (Department: 3745)

Rotary kinetic fluid motors or pumps

Working fluid passage or distributing means associated with...

Plural distributing means immediately upstream of runner

C415S199500, C415S176000, C415S201000

Reexamination Certificate

active

06322321

ABSTRACT:

FIELD OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a nozzle chamber warming-up structure for a steam turbine. More particularly, it relates to a nozzle chamber warming-up structure for a steam turbine, in which a nozzle chamber is warmed uniformly in the warming-up process to prevent an excessive contact of a seal portion of a dummy ring, with which the nozzle chamber is formed integrally, with a rotor.
FIG. 3
is a sectional view showing a prior art structure of a main steam introducing portion for a steam turbine. In
FIG. 3
, a reference numeral
11
denotes a main steam inlet port,
12
denotes a casing, and
13
denotes a rotor. A dummy ring
14
is disposed around the rotor
13
, and a seal portion
15
is provided between the dummy ring
14
and the periphery of the rotor
13
. A nozzle chamber
16
is formed around the rotor
13
integrally with the dummy ring
14
, and has nozzles
17
. The nozzle chamber
16
introduces main steam
30
through the main steam inlet port
11
, and supplies steam to a high pressure turbine section
20
through the nozzles
17
.
FIG. 3
is a sectional view showing a structure of a main steam introducing portion for a steam turbine relating to the present invention. In
FIG. 3
, reference numeral
11
denotes a main steam inlet port,
12
denotes a casing, and
13
denotes a rotor. A dummy ring
14
is disposed around the rotor
13
, and a seal portion
15
is provided between the dummy ring
14
and the periphery of the rotor
13
. A nozzle chamber
16
is formed around the rotor
13
integrally with the dummy ring
14
, and has nozzles
17
. The nozzle chamber
16
introduces main steam
30
through the main steam inlet port
11
, and supplies steam to a high pressure turbine section
20
through the nozzles
17
.
Reference numeral
18
denotes a stator blade of one stage in the high pressure turbine section
20
, and
19
denotes a rotor blade of one stage fixed to the rotor
13
in the high pressure turbine section
20
. Thus, the high pressure turbine section
20
has the dummy ring
14
, many stator blades fixed to the periphery of inside wall of the casing
12
, and many rotor blades fixed to the periphery of the rotor
13
, and a steam passage is formed by alternately arranging these stator blades and rotor blades in the axial direction.
FIG. 4
is a sectional view taken along the line B—B of FIG.
3
. The construction is such that steam inlets
21
and
22
are provided to introduce the main steam
30
to the nozzle chamber
16
, and a steam chamber is divided into four chambers denoted by
23
a
,
23
b
,
23
c
and
23
d
by means of ribs
24
a
,
24
b
,
24
c
and
24
d
.
FIG. 5
is a sectional view taken along the line C—C of FIG.
3
. The nozzle chamber
16
is vertically divided into two chambers, which are combined with each other. The nozzles
17
are provided only in the upper half of the nozzle chamber
16
, constituting partial insertion type nozzles. This is because the cross sectional area of steam passage is increased by halving the inflow area of nozzle with respect to a certain amount of inflow steam.
In the steam turbine configured as described above, the main steam
30
enters the casing
12
through the steam inlet port
11
, being introduced into the nozzle chamber
16
, and is blown off to the steam passage of the high pressure turbine section
20
through the nozzles
17
provided in the upper half of the nozzle chamber
16
. The steam blown off from the nozzles
17
passes through the one-stage stator blade
18
and rotor blade
19
of the high pressure turbine section
20
, flows in a space between the stator blades and the rotor blades arranged in a multi-stage form, and drives the rotor
13
to do work. Thereafter, the steam is discharged through an exhaust system (not shown).
The dummy ring
14
is disposed around the rotor
13
between the high pressure turbine section
20
and the adjacent intermediate pressure turbine section, and provides a seal between both of the turbine sections to prevent a leak of steam from the high pressure side to the intermediate pressure side.
The nozzle chamber
16
of a partial insertion type in the above-described turbine has a construction such that the introduced main steam enters the steam chambers
23
a
and
23
d
in the upper half through the steam inlets
21
and
22
as shown in
FIGS. 4 and 5
, and flows out to the steam passage of the high pressure turbine section
20
through nozzles
17
provided in the upper half as shown in
FIG. 5
, but the main steam does not flow into the steam chambers
23
b
and
23
c
in the lower half. Therefore, for the nozzle chamber
16
, the effect of thermal deformation differs between the upper-half steam chambers
23
a
and
23
d
into which the steam flows and the lower-half steam chambers
23
b
and
23
c
into which the steam does not flow, so that nonuniform thermal deformation occurs.
As described above, in the nozzle of a partial insertion type of the steam turbine relating to the present invention, there is a great difference in thermal expansion between the upper-half steam chambers
23
a
and
23
d
into which the steam flows and the lower-half steam chambers
23
b
and
23
c
into which the steam does not flow, so that the whole is not deformed uniformly, and nonuniform thermal deformation occurs. Therefore, the seal portion
15
of the dummy ring
14
integrated with the nozzle chamber
16
comes excessively into contact with the rotor
13
. As a result, vibrations sometimes occur. To avoid this trouble, warm-up is performed. However, because the ribs
24
b
,
24
c
and
24
d
are present, the lower-half steam chambers
23
b
and
23
c
cannot be warmed up, and only the upper half is warmed up. Therefore, it is difficult to warm up the whole of the nozzle chamber uniformly.
OBJECT AND SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a nozzle chamber warming-up structure that can warm up the whole of nozzles uniformly in the warming-up process in a partial insertion type nozzle chamber in which a steam chamber of a steam turbine is divided, in order to prevent nonuniform thermal deformation of the nozzle chamber and to prevent vibrations caused by an excessive contact of a dummy ring provided integrally with the nozzle chamber with a rotor caused by this nonuniform thermal deformation.
To solve the aforementioned problems, the present invention provides the following means.
In a nozzle chamber warming-up structure for a steam turbine, in which a nozzle chamber for introducing main steam to the periphery of a rotor is provided, the nozzle chamber is divided into four steam chambers, and main steam is caused to flow out to a steam passage of a turbine through nozzles disposed so as to correspond to the steam chambers in the upper half of the nozzle chamber, through holes are formed in walls dividing the steam chamber so that the divided steam chambers communicate with each other via the through holes, by which warming-up steam is made capable of flowing in the steam chambers.
In the nozzle chamber warming-up structure in accordance with the present invention, in the warming-up process, warming-up steam is introduced into the nozzle chamber, and is caused to flow to the steam chambers in the nozzle chamber in succession to warm up the steam chambers uniformly. Conventionally, the construction is such that two inlets of main steam to the partial insertion type nozzle chamber are provided at right and left, and steam flows in through these inlets uniformly, and flows out to the steam passage through the nozzles disposed in the upper half of the nozzle chamber. For such a construction, the steam chambers are divided, and the warming-up steam cannot be caused to flow to the lower-half steam chamber into which the steam does not flow, so that it is difficult to warm up the whole of the nozzle chamber uniformly.
In the present invention, through holes are formed to cause steam spaces to communicate with each other, and further the angles of nozzle blades ar

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