JPH0615809B2 - Turbine thrust adjustment device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thrust force adjusting device for a turbine rotor,
In particular, the present invention relates to a thrust force adjusting device for a steam turbine rotor having a high main steam pressure.

[Background of the Invention]

Generally, in an axial flow body machine such as a steam turbine, a thrust force is generated and is received by a thrust bearing. This thrust force increases as the pressure of the fluid to be handled increases, and in a large capacity ultra high pressure turbine,
It may be several tens of tons, and for those with a particularly large capacity, it may reach up to hundreds of tons.

FIG. 1 shows a typical two-stage reheat turbine configuration. The high pressure rotor 1, the medium pressure rotor 2, and the low pressure rotors 3a and 3b are
It is connected to one shaft by a coupling 5, and each rotor is supported by bearings near both ends. Medium pressure rotor 2
Is integrally provided with a thrust collar portion 6, and the collar portion 6 is supported by a thrust bearing 7. The main steam generated in the boiler 8 flows into the high-pressure turbine casing 10 through the main steam pipe 9, works in the ultra-high pressure stage 11, passes through the low-pressure first reheat steam pipe 12, and then the first reheat of the boiler is performed. Heat part 1
Inflow to 3. The steam reheated in the first reheating section 13 passes through the high temperature first reheat steam pipe 14 and flows into the high pressure stage 15 arranged in the high pressure turbine casing 10 to perform work.
The steam that has worked in the high-pressure stage 15 passes through the low-temperature second reheat pipe 16, is reheated in the second reheat section 17 of the boiler, and is heated to the second high temperature.
It flows into the intermediate pressure casing 19 via the reheat pipe 18.
The steam that has worked in the intermediate pressure stages 20a and 20b passes through the crossover pipe 21 and flows into the low pressure casings 22a and 22b. The vapor which has worked at the low pressure stages 23a, 23b, 23c and 23d and has become low pressure and low temperature is stored in the condenser 24.
It condenses in a and 24b and is condensed. In the turbine having such a configuration, since the intermediate pressure stage and the low pressure stage are bilaterally symmetrical, the thrust forces cancel each other out, and the thrust force becomes small. However, since the ultrahigh pressure stage 11 and the high pressure stage 15 arranged in the high pressure casing have different sizes and different working steam pressures flowing therethrough, a thrust force is generated. FIG. 2 shows the ultrahigh pressure stage 1
1 and a high-pressure stage 15 are shown, and the high-pressure rotor 1 has a high-pressure casing 10 in which the ultra-high-pressure stage 11 and the high-pressure stage 15 are the same.
It is located inside. The ultra-high pressure stage and the high pressure stage are each composed of a multi-stage disk portion 28 having a moving blade 26 and a shroud ring 27. Near both ends of the high-pressure rotor 1, the diameter becomes smaller in a stepped manner, and the small-diameter portion is supported by the bearing 4.

Generally, the thrust force of an axial turbine is roughly classified into the following three types.

(1) Bucket thrust force (2) Wheel thrust force (3) Packing thrust force Bucket thrust force 32 is the sum of the axial force of the steam force acting on the profile of the blade, and the pressure difference before and after the blade, The wheel thrust force 33 is determined by the degree of reaction of the moving blade, and the wheel thrust force 33 is a thrust force based on the pressure difference between the front and rear of the rotor disk portion 28, and changes depending on the degree of reaction of the root portion of the moving blade. On the other hand, the packing thrust force 34 is a thrust generated on the stepped portion of the rotor shaft 1 and is generated where the outer diameter of the shaft shaft changes.

As is clear from FIG. 2, the directions of the thrust forces are opposite to each other in the ultra-high pressure stage 11 and the high-pressure stage 15, so the sum of the thrust forces to the right is equal to the sum of the thrust forces to the left. If so, the thrust force should be substantially zero, but since the working steam pressures in the ultrahigh pressure stage 11 and the high pressure stage 15 are different, either thrust force prevails and thrust occurs in the rotor 1. Of the above three thrust forces, the largest is usually the packing thrust force, and in designing the turbine, the outer diameter difference between the stepped portions on the left and right of the rotor is made different so that The total thrust force is made equal.

Fig. 3 shows a sealing packing steam system for a shaft packing part which generates packing thrust force. The shaft seal of the high-pressure turbine casing 10 including the ultra-high pressure stage 11 and the high-pressure stage 15 includes a first shaft packing portion 35 and a second shaft packing portion 35 from the high pressure side.
It is composed of a shaft packing part 36 and a third shaft packing part 37. First shaft packing section 35
In particular, in a supercritical pressure two-stage reheat turbine, the exhaust pressure of the ultrahigh pressure part reaches about 80 kg / cm ² abs, so
The leak line of the book constitutes the shaft seal structure. The high-pressure leak line 42 is usually a 30 kg / cm ² abs line and is connected to, for example, the low-temperature second reheat line 16, and the medium-pressure leak line 43 is a 10 kg / cm ² abs line. Collect in the air. The third seal steam line 44 is supplied with the seal steam adjusted by the seal steam regulator 47 to a constant pressure, for example, 1.3 kg / cm ² abs. The fourth ground capacitor line 45 is under atmospheric pressure and is connected to the ground capacitor 46. As shown in FIG. 3, since the leak vapor pressure of the first shaft packing part 35 and the leak vapor pressure of the third shaft seal packing part 37 are different from each other, a step portion is formed on the rotor 1 at a portion where the leak vapor pressure is different. If provided,
It is possible to make the left and right packing thrust forces different. Therefore, at the turbine design stage, it is possible to predict the thrust forces and set the rotor step to set the shaft diameter difference to the optimum value so that the thrust forces of different directions cancel each other out. Is.

By the way, in such a steam turbine, the pressure distribution inside the turbine changes over time due to a decrease in blade efficiency, and the thrust force also changes accordingly. In particular, super-supercritical thermal power plants (main steam pressure
At 4500 to 5000 psig and main steam temperature of 1100 to 1200 ° F), it is expected that the pressure distribution inside the turbine will change due to the particle erosion of the turbine nozzle blade due to the oxide scale from the boiler and the adhesion of the dissolved metal to the turbine blade. It

Reference `` The Second Year of Operating Experience with
The Philo Supercritical-pressure Unite '' Proceedin
As described in g of the America Power Conference Vol XXI-1959, the thrust force becomes too large due to the adhesion of the dissolved metal to the turbine blades at the Philo plant.
It is stated that the wing profile was modified to shut down the plant for an extended period of time.

[Object of the Invention]

The present invention provides a thrust force adjusting device capable of reducing the thrust force below a permissible value without subjecting the turbine to special processing and against the secular change of the thrust force, and without stopping the plant. Especially.

[Outline of Invention]

That is, according to the present invention, the packings that are continuously provided in the axial direction of the turbine rotor are formed by changing the shaft diameters of the rotors at the portions corresponding to the adjacent packings. By means of a passage means communicating with the closed space and constituted by a pressure source outside the turbine, a pressure adjusting means provided in the passage means for adjusting the liquid pressure in the closed space, and a thrust of the turbine rotor. Means for detecting the thrust force of the bearing, means for detecting the pressure in the closed space, means for calculating a pressure value for obtaining a desired thrust force from the signal of the thrust force detecting means, and the calculated pressure A control means for controlling the pressure adjusting means so as to cancel the deviation between the pressure value and the closed space pressure value is provided to achieve the intended purpose. .

Example of Invention

FIG. 4 shows a seal steam system of a high-pressure turbine equipped with a thrust force adjusting device embodying the present invention, and FIG. 5 shows a detailed sectional view of the first shaft packing part 35. Fourth
In the figure, the intermediate pressure leak line 43, the seal vapor line 44, and the ground condenser line 45 are configured similarly to the conventional product shown in FIG. High pressure leak line 54
Is provided between the high pressure leakage chamber 52 formed around the step portion 1a where the rotor 1 changes from the large diameter to the small diameter, and the tank 56 of the header or the small capacity, and the tank 56 has the adjusting valves 57a and 57b. , 57c, 57d through line 5
It communicates with 8a, 58b, 58c and 58d. First high pressure adjustment line 58a, second high pressure adjustment line 58b, first
The low pressure adjustment line 58c and the second low pressure adjustment line 58d are
They are connected to the high temperature first reheat steam pipe, the low temperature second reheat line, the deaerator and the condenser, respectively. The exhaust pressure 80 Kg / cm ² abs about plant Ultra high pressure stage 11, the pressure of each line of 58a~d ^{is, 70Kg / cm 2 abs, 30Kg} / cm 2 abs, 1
It becomes about 0 Kg / cm ² abs and 0.05 Kg / cm ² abs.

In FIG. 5, the leaked steam 48 from the ultrahigh pressure exhaust portion flows leftward through the gap between the rotor 1 and the comb teeth 50, and flows into the leaked steam chamber 52. Comb teeth 50 are packed head 5
1 and the packing head 51 is attached to the rotor 1
A plurality of them are arranged side by side in the axial direction and are held by the packing case 49. The steam in the leaked steam chamber 52 is guided to the tank 56 through the high pressure leak line 54. On the other hand, residual leaked steam 55
Further flows between the packing comb teeth 50 and the rotor 1 on the low pressure side, and then flows to the intermediate pressure leak line 43. Leak steam room 5
The rotor diameter at 2 points is from high pressure side diameter φD to low pressure side diameter φD
_It has changed to ₀ . If the steam pressure in the chamber 52 is P ₀ , the thrust force F having the magnitude shown below acts on the rotor 1 at the portion where the diameter changes, that is, the stepped portion 1a.

Becomes Conventionally, since the high-pressure leak line is connected to the low-pressure second reheat line or the like, the P ₀ value depends on the pressure at the connection destination and is constant during normal operation.

In the present invention, the value of P ₀ can be controlled from the outside so that the thrust force F can be changed. That is,
According to the system diagram of FIG. 4, the pressure in the chamber 52 is
Equal to the pressure of. The pressure of the tank 56 is adjusted by adjusting valves 57a to 57d.
It can be varied from a maximum 70 Kg / cm ² abs to a minimum 0.05 Kg / cm ² abs by adjusting the degree of opening. Therefore, when the pressure P _{0 of the} chamber 52 is 30 kg / cm ² abs,
If the thrust force generated in the entire high-pressure rotor 1 is set to be equal to or less than the allowable value, when the leftward thrust force of the rotor 1 increases due to aging, the pressure P _{0 in the} chamber 52 should be increased. Therefore, the increased thrust force can be canceled out. On the contrary, when the thrust force to the right increases, the thrust force F generated in the stepped portion 1a becomes smaller by reducing the pressure P _{0 of the} chamber 52, and the thrust force can be balanced as a whole. .

As an example, the setting chamber 5 is set to D = 724 mm and D ₀ = 660 mm.
2 pressure P ₀ is a maximum of 60 kg / cm ² abs and a minimum of 20 kg / cm
^When changing to ² abs, the change in thrust force F is about 28 tons.
Becomes In other words, if the set value is set in the middle with the thrust force, even if the thrust force changes to the range of ± 14 tons,
You can cancel it. Since the secular change of the thrust force does not occur suddenly, the adjusting valves 57a to 57d of the lines 58a to 58d connected to the tank 56 are manually operated needle valves, and the operator periodically checks the surface of the thrust bearing. By measuring the pressure, adjusting the valves 57a to 57d, and adjusting the tank internal pressure to a desired pressure value, the thrust force can be controlled to be equal to or lower than the allowable value.

In addition, since the secular change of thrust force tends to increase in a specific direction, the initial setting is the direction in which the packing thrust force in the direction of increasing with time is the maximum or the direction opposite to the direction of increasing with increasing secular change. If the value of P ₀ is set so as to minimize the packing thrust force of, the adjustment range of the secular change becomes even larger.

The pressure in the steam leakage chamber 52 can be freely set within a range that does not impair the sealing effect of the first shaft packing part 35, but if the exhaust pressure of the ultra-high pressure stage is about 80 kg / cm ² abs, The adjustment range is preferably 60 to ²⁰ kg / cm ² abs. The lower limit 20 Kg / cm ² abs is better to hold to a higher value than the pressure 10 Kg / cm ² abs medium pressure Lee Klein 43, as a whole shear shift Patsu King unit 35, toward the exhaust side to the rotor end gradually The leak pressure is low and the sealing effect is not impaired.

The rotor step 1a and the steam leak chamber where the steam pressure can be adjusted can be provided at the location of the medium pressure leak line, but in this case, the maximum pressure of the chamber is higher than the pressure of the high pressure leak line. Since it has to be set to a low value, the adjustment range of thrust force becomes narrow. Further, it is also possible to provide this packing force adjusting device on the second shaft packing portion 36. In this case, the medium pressure leak line 4
Since the rotor is provided at the third position, the step of the rotor may be provided at this portion, and the pressure regulating valve may be arranged at the intermediate pressure leak line. It is also possible to provide two packing thrust force adjusting devices for one rotor.

FIG. 6 shows an embodiment in which the thrust force is automatically adjusted. It is known that the secular change of the thrust force occurs only in a specific direction. Therefore, a temperature sensor such as the thermocouple 60 is provided in the thrust bearing 7 and the thrust bearing metal temperature T ₀ is set in the thrust force calculator 61. Input,
The thrust force F ₀ is calculated from the metal temperature T ₀ . The calculated thrust force F ₀ is compared with the allowable value F _r by the comparator or calculator 62. If when exceeding the allowable value, enter the deviation ΔF to the arithmetic unit 63 obtains the leakage steam chamber 52 the pressure P ₀ required to cancel the deviation, the P ₀
And the actual pressure P in the chamber 52 are compared by the comparator 64, and the adjusting valves 57a to 57d are feed-back controlled via the actuator 70 so that the deviation ΔP becomes zero. That is, the pressure P detected by the pressure sensor 65 is P required to cancel the deviation ΔF between the allowable thrust F _r and the actual thrust force F _0.
The feedback circuit is configured with the value of ₀ as the target value.

In this embodiment, the thrust force is constantly monitored during the operation of the turbine. When the thrust force exceeds the allowable value, the thrust force is adjusted, and the thrust force can be maintained below the allowable value. It is also possible to activate the alarm device 66 when the thrust force exceeds the allowable value. In addition to the thermocouple, the thrust force can be detected directly by a pressure sensor. In this case, F ₀ can be directly detected, so that the computing unit 61 can be omitted.

〔The invention's effect〕

As described above, according to the present invention, it is possible to reduce the excessive thrust force due to the secular change of the thrust force without stopping and disassembling the turbine.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a known two-stage reheat turbine, FIG. 2 is a schematic diagram for explaining the thrust force of a high-pressure turbine, and FIG. 3 is a system diagram showing a known seal steam system, FIG. 4 is a system diagram showing a seal steam system of a high-pressure turbine embodying the present invention, FIG. 5 is a detailed sectional view of a shaft packing portion, and FIG. 6 is a control block diagram of a regulating valve. 1 ... High-pressure rotor, 2 ... Medium-pressure rotor, 4 ... Bearing, 7
...... Thrust bearing, 10 ...... High-pressure turbine casing,
11 ... Ultra-high pressure stage, 15 ... High pressure stage, 32 ... Bucket thrust force, 33 ... Wheel thrust force, 34 ... Packing thrust force, 35 ... First shaft shifting part, 43 ... Medium Pressure leak line, 52 ... Leakage steam chamber,
56 ... Tank, 57a-d ... Regulator valve, 60 ... Thermocouple, 61 ... Thrust force calculator, 70 ... Actuator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoaki Shibashita 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi factory (72) Inventor Ryoichi Kaneko 3 Saiwaicho, Hitachi City, Ibaraki Prefecture 1-1-1, Hitachi Ltd., Hitachi Works (56) References Japanese Patent Publication No. 46-3209 (JP, B1) Japanese Publication No. 44-5624 (JP, B1) Japanese Publication No. 52-24162 (JP, B2) )

Claims (2)

[Claims] 1. A rotor having a plurality of packings axially continuous near the end of the turbine rotor for sealing between the casing and the turbine rotor, and if the rotor shaft diameters of the portions corresponding to the adjacent packings are different. And a fluid passage in the closed space provided in the passage means, the passage means communicating with a closed space formed by the adjacent packing and the rotor and communicating with a pressure source outside the turbine. Pressure adjusting means, thrust force detecting means for detecting the thrust force of the thrust bearing of the turbine rotor, pressure detecting means for detecting the pressure in the closed space, and a desired thrust from the signal of the thrust force detecting means. A means for calculating a pressure value for converting into a force, and the pressure adjusting means for canceling the deviation between the calculated pressure value and the closed space pressure value. Thrust force adjusting device of the turbine, characterized in that a Gosuru control means. 2. The pressure adjusting means comprises a pressure header communicating with the closed space, a conduit communicating with a plurality of pressure sources different from the header, and a regulating valve provided in the conduit. The thrust force adjusting device for a turbine according to claim 1, wherein