JPH0242103A - Pressure reducing turbine and steam compressor - Google Patents

Abstract

PURPOSE:To reduce the number of shaft sheet portions to aim at reduction of loss due to steam leak by arranging the pressure reducing turbine and the steam compressor of a thermal power generation plant as a bisymmetrical double-flow type and constructing it in a way that they are housed in a casing formed integral therewith. CONSTITUTION:A steam inlet 1 is provided at the central portion of a pressure reducing valve, steam flowing in the steam inlet 1 bisymmetrically flows both sides and then it flows out a pair of, left and right, steam outlets 2, 2, in a such way, the pressure reducing turbine is constructed as a double-flow type. A steam inlet 3 and a steam outlet 4 are provided at both end sides of the pressure reducing turbine via dummy rings 9 and also steam compressors providing stator blades and rotor blades are bisymmetrically arranged and the pressure reducing turbine and the casing 11 of the pressure reducing turbine and the steam compressor are integrally formed. Grand rings 10 are provided outside the steam compressor. The casings 11 are positioned at bearing stands by keys 14. Further, a rotor 15 is held by a bearing 13 as one body with the pressure reducing turbine portion and a steam compressor portion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is provided to maintain high efficiency over a wide range of loads in a supercritical pressure thermal power plant operated at variable pressure. Concerning improvements in pressure reducing turbines and steam compressors.

[Conventional technology]

In thermal power plants, there is no improvement in steam conditions to increase plant efficiency, and currently the main steam pressure is 246
kg/cyt21! Many supercritical pressure plants with main steam temperature of 538°C and reheat steam temperature of 538°C to 566°C have been constructed. When these plants are operated continuously at rated load, there is no problem with the above steam conditions, but
If the frequency of start-up/shutdown and load changes to low loads increases, the temperature change at the outlet of the governor stage of the turbine will increase if the above steam conditions remain unchanged, and the problem of thermal stress in the rotor will arise.

In order to reduce temperature changes at the outlet of the turbine governor stage due to load changes, a method of changing the main steam pressure according to the load is suitable. This method is called variable voltage operation method.

When the variable pressure operation method is applied to the entire plant including the boiler,
The gain of reducing feed water pump power due to the drop in feed water pressure at low loads can be obtained, so in addition to reducing the throttling loss of the steam control valve and other gains, the turbine side also gains gains in efficiency improvement in addition to thermal stress reduction. . However, for the boiler side,
Changing the furnace pressure changes the furnace temperature, creating boiler thermal stress problems.

Therefore, in order to reduce the main steam pressure while maintaining the boiler furnace pressure during partial load, a pressure reducing valve (BT valve) is installed between the secondary superheater and the secondary superheater. Ta.

The loss of pressure caused by this pressure reducing valve will directly reduce the efficiency of the plant, so a pressure reducing turbine is installed in place of the pressure reducing valve, and steam is passed through the kneader to generate 1! This pressure reducing turbine (2) is used to drive the machine and recover power, as shown in Figure 3.
It has been proposed to drive a separate vapor compressor 061 to compress low-temperature reheated steam to improve plant efficiency.

When a pressure-reducing turbine is installed instead of a pressure-reducing valve to drive a steam compressor and compress low-temperature reheated steam, the rotation speed of the pressure-reducing turbine is fixed compared to driving a generator with a constant rotation speed. This allows the reduced pressure turbine to maintain high efficiency over a wide range of loads. Also, is it a set of a pressure reducing turbine and a steam compressor that are relatively heavy? Since it can be easily installed above the boiler where the superheater or reheater is located, piping is simplified, making it possible to reinforce the boiler steel frame and install a heavy generator high above the boiler, or to route large steam piping. This method is advantageous in terms of boiler purchasing, as it eliminates the need for pipework, and also reduces mechanical losses in piping.

In Fig. 3, (211 is an economizer, a draft furnace, and a draft superheater; 211 is a pressure-reducing turbine steam control valve;
@ is the auxiliary superheater, (281 is the secondary superheater, (to) is the high pressure turbine, (to) is the main turbine steam control valve, C31) is the high pressure pipe, 6 valve, O3 low temperature reheat steam pipe check Ben, c!
3-piece reheater, 04) is an intercept valve, and 09 is an intermediate pressure turbine.

(to) is the low pressure/Z pass valve, c3η is the condenser, (to) is the low pressure turbine, c (1 is the generator, (41 is the condensate pump,
0D is a low pressure heater, (42) is a deaerator, (4'3 is a water pump, (441 is a high pressure heater, O5), (4
(:J, (4η, (4□□□ is a cutoff valve, (4■ is a pressure reducing valve, and ra■ is a bypass valve.

[Problem to be solved by the invention]

When a pressure-reducing turbine is installed instead of a pressure-reducing valve to drive a steam compressor to compress low-temperature reheated steam, if the pressure-reducing turbine and steam compressor are separate, each gland ring (rotor and casing) The amount of steam leaking at the shaft seal between the two ends increases, resulting in increased loss.

Also, if the decompression pin and vapor compressor are separated.

It requires a large space, which is disadvantageous in terms of equipment placement.

[Means to solve the problem]

In order to solve the above-mentioned conventional problems, the present invention arranges a valve and a double-flow pressure reducing turbine in parallel in the middle of a pipe connecting the primary superheater and the secondary superheater of a variable voltage operating thermal power plant. At the same time, seven steam pressure machines are symmetrically connected to both ends of the same pressure reducing turbine.

The present invention also proposes a reduced pressure turbine and a steam compressor, characterized in that the single chamber of the reduced pressure turbine and the working chamber of the steam compressor are integrally formed.

[For production]

Since the present invention is configured as described above, Grand 1-
The amount of leaked steam is reduced and efficiency is improved.

The thrust is also perfectly balanced, increasing reliability. Furthermore, the whole can be made more compact.

This is advantageous in terms of placement.

〔Example〕

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. In this figure, (1) is the steam inlet of the pressure reducing turbine, (2+
Vi steam outlet of the pressure reducing turbine, (3) is the steam inlet of the steam compressor, (4) is the steam outlet of the steam compressor, X51 is the ME
The nozzle of the E-turbine, (6) is the moving leg of the pressure-reducing turbine.

(Stator blade of 71Vi vapor compressor, (8) is the movement of the vapor compressor.

As described above, the pressure reducing turbine of this embodiment is of a double-flow type in which the steam that rises in the center is symmetrically downward to both sides. and on the outside of the double-flow type pressure reducing turbine.

The stator blades (7) and rotor blades (8) of the steam compressor are arranged symmetrically with a dummy ring (9) in between. The pressure reducing turbine and the steam compressor casing t11) are integrally formed.

A gland ring (1) is disposed on the outside of the vapor compressor, and a bearing (1) is formed integrally with the bearing stand (α2).
13).

Steam inlet H of the pressure reducing turbine provided in the center of the single chamber αB
) l-1, the steam outlet (2) is communicated with the outlet of the pressure reducing turbine steam control valve (c) of the power plant illustrated in FIG. 3, and the steam outlet (2) is communicated with the inlet of the cutoff valve Oe. Also, the steam inlet of the vapor compressor (31 is the outlet of the shutoff valve (47)).

The steam outlets (4) communicate with the inlets of the shutoff valves.

Then, during partial load, the steam exiting the boiler's primary superheater is transferred to the pressure reducing turbine (2 main steam stop valves (4)).

The steam is led through a steam regulator to the pressure reducing turbine steam inlet (1). This steam is transferred to a double-flow reduced pressure turbine nozzle (5)
, passes through the rotor blades (6), drives the rotor (1), is discharged from the steam outlet (2), passes through the shutoff valve G161, passes through the auxiliary superheater (5), and flows to the secondary superheater (to). , the low-temperature reheated steam leaving the high-pressure turbine is led to the steam compressor steam inlet (3) through the isolation valve (4η). The steam is compressed and discharged through the steam outlet (4) and flows through the isolation valve (48) to the reheater G3.

In this way, while maintaining the pressure in the boiler furnace,
The pressure of the main steam is reduced by the pressure reducing turbine Q (a) to reduce the thermal stress of the high pressure turbine blade, and the reduced pressure is recovered by the steam compressor (to).

In this embodiment, the casings of the pressure reducing turbine and the steam compressor are integrally formed and are of a symmetrical double-flow type, so that the amount of leakage from the graft is significantly reduced. This will be explained using drawings. Figure 2 (a) is a diagram conceptually showing the equipment arrangement for the conventional single-flow, two-chamber case, and Figure 2 (bl is the present embodiment's galvanometer, single-chamber case). .

In the figure, T indicates a pressure reducing turbine, and Comp indicates a steam compressor. Also A and B.

C and D are respectively the inlet and outlet of the decompression turbine.

Gran P at the outlet and inlet of the vapor compressor are shown by h, respectively.

Now, for the conventional case (Fig. 2(a)), A and B.

An example of the pressure and leakage amount at each part of C and D.

The total amount of leakage is approximately 38 t/h, and the loss due to this amount of leakage is estimated to be approximately 1,000 to 2,000 kW. - In the case of this embodiment (FIG. 2(b)), since a double flow type pressure reducing turbine is used, leakage in section A will not occur. Further, at part 0, the pressure in part B is higher and leaks from B to C, but there is no leakage from part 0. Therefore, the leakage amount is 9 to 18 t/h, and the loss due to this leakage amount is halved to about 500 to LOOOkW.

Next, we will discuss the thrust that acts on the pressure reducing turbine and steam compressor. In this embodiment, the pressure reducing turbine is a double flow type, so the thrust acting on the pressure reducing turbine is canceled out between the symmetrical turbine parts.

Furthermore, since the vapor compressors are also arranged symmetrically, the thrusts acting on each one cancel each other out. The thrust is therefore perfectly balanced.

〔Effect of the invention〕

In the present invention, by arranging the decompression turbine and the steam compressor in a symmetrical double-flow type and housing them in an integrally formed chassis, the number of shaft seals can be reduced. Loss due to leakage is reduced. Also, due to the double flow type arrangement (-), the thrust is perfectly balanced.

The bearing can be simplified. Furthermore, since the compartment is integrated, it does not require a large area for arrangement, which is advantageous.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing one embodiment of the present invention, and FIG.
FIG. 3 is a system diagram showing an example of a thermal power plant to which the present invention is applied. ri...steam population of the pressure reducing turbine; 2)...steam outlet of the pressure reducing turbine; 3)...steam population of the steam compressor; 4)...steam outlet of the steam compressor; 5)... Nozzle of pressure-reducing turbine; 6)... Moving blade of pressure-reducing turbine; (7)... Static line of steam compressor; (8)... Moving blade of steam compressor; (9)... Dummy ring ;0α...Grand ring; (II
)...Car compartment; (13...Bearing stand; (l
R...Bearing; I...Key; Kasumi...Rotor; Pull)...Economizer; (2z...Furnace: C3
1...-next week p! 8 units: e41...Reducing turbine:
cp51...Reducing turbine steam control valve; C61.
...Vapor compressor; Punishment...Auxiliary superheater; (281.
...Secondary superheater; Kan...High pressure turbine; ■...
Main turbine steam control valve: C31)...High pressure bypass valve; (132...Low temperature reheat steam pipe reverse valve: G'!I...
Reheater: C34+...Intercept valve; (
To)...Intermediate pressure turbine; S6)...Low pressure bypass valve; C171...Condenser; ■...Low pressure turbine; G9...Power generation key; (11...Condensate pump; ( 4
1)...Low pressure heater; (4z...Deaerator; (4,1
...Water pump; (,141...High pressure heater; (c), (46), <47), (431.
...Shutoff valve; (49...Reducing valve; ■...Binosu valve fee embedded Patent attorney Sakama Akigai 2 people Figure 2 (b)

Claims (1)

[Claims] A valve and a double-flow pressure-reducing turbine are installed in parallel in the middle of the pipeline connecting the primary superheater and secondary superheater of a variable-pressure operating thermal power plant, and a steam compressor is installed at each end of the pressure-reducing turbine. A reduced pressure turbine and a steam compressor, characterized in that the reduced pressure turbine and the vapor compressor have a casing integrally formed with the casing of the reduced pressure turbine and the vapor compressor.