JPS6347882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for maintaining the axis of a rotating shaft of an axial flow mechanical device such as a gas turbine-driven power generation device, a steam turbine-driven power generation device, or a motor-driven blower device.

Conventionally, in the method of maintaining the axis of the rotating shaft of an axial flow machine as described above, the supporting device of the rotating shaft, which is heated during operation, is cooled using lubricating oil used for bearing lubrication. This purpose was achieved by reducing the amount of change in the axis during operation and by using a water-cooled support leg device.

However, in such devices, the cooling fluid used, such as lubricating oil, cooling water,
In some cases, loss of power to supply air, etc., piping equipment to supply cooling fluid, etc., or equipment such as gear joints and flexible joints used to accommodate changes in shaft center may be required, and cooling may also be required. The disadvantage was that it required the cost of the medium itself.

Furthermore, in the conventional shaft center holding method, in addition to cooling the support device, a method is taken in which the shaft center is eccentrically set in advance when it is cold so that the shaft center is on a straight line during operation. I came here.

In such conventional methods, the rotating shaft, which is a rotating body, is bent and connected when it is cold.
There was a stability issue during startup.

In this case, the stability of the bearing or the centering method is troublesome due to the rigidity of the rotating shaft, and there is a drawback that extra time and expense are required in terms of design, assembly and maintenance.

On the other hand, gear joints and flexible joints are used to reduce the rigidity of the rotating shaft and make it easier to adjust the axis, but in addition to being expensive, the rigidity of the rotating shaft becomes unstable and non-linear Vibration may occur and stable operation may not be possible.

Therefore, in the past, the current situation is to perform many calculations such as the critical speed of the rotating shaft, bearing support rigidity, stability, etc., calculate the stability of the rotating shaft, and then perform assembly and maintenance.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems in the method of holding the center of a rotating shaft of an axial flow machine as described above. The object of the present invention is to provide a support method that allows the shaft center to be assembled in a straight line and to maintain the straight line at least during operation.

That is, the present invention aims to minimize the amount of elongation of the support device for the rotating shaft and to relatively reduce the difference in elongation between the support devices. By using a material for the support legs of a support device that has a higher thermal elongation upward than other support devices, the difference in thermal elongation can be made the same as for the support legs of a support device that has a higher thermal elongation in the upper direction than other support devices.

The details of the present invention will be explained below based on the drawings. FIG. 1 shows a blower device in which a blower 10 is driven by an electric motor 11 as an axial flow mechanical device according to a first embodiment of the present invention.

A rotating shaft 10A of this blower 10 is connected to a support device 13.
and 14, and a rotating shaft 11A of the electric motor 11 is supported by supporting devices 15 and 16, and these rotating shafts 10A and 11A are coupled by a shaft coupling 12.

Next, A and B indicate the positions of the support bearings for the rotating shaft 10A of the blower 10, and C and D indicate the positions of the supporting bearings for the rotating shaft 11A of the electric motor 11, respectively.

In such an axial flow mechanical device, the rotating shaft 10
Figure 2 shows changes in the axis focusing on the axis of A and 11A.
As in FIG. 1, B indicates the support bearing of the rotating shaft 10A of the blower 10, and C and D indicate the positions of the supporting bearings of the rotating shaft 11A of the electric motor 11, respectively.

In FIG. 2, the shaft centers of the rotating shafts 10A and 11A of the blower 10 and electric motor 11 are Y ₁ when cold.
If there is a straight line _f1 at a height of , then during operation the line will rise to a height of _Y2 , and the axes of the rotating shafts 10A and 11A are shown by broken lines.
Suppose it curves like f ₂ .

The reason for this is simply assuming that the bearing point 17 of the blower 10 rises to the same point 18 at the operating height _Y2 , and the other bearing point 19
The blower 10 adiabatically compresses the air indicated by the arrow a in FIG. It shows that

On the other hand, the axis of the rotating shaft 11A of the generator 11 is a straight line f 1 at the position Y ₁ when the bearing points 21 and 23 are cold, but when it is in operation, it is a straight line f ₁ at the position 22 and 2 2.
4, and is approximately at the same height as point 18.

Here, the bearing point 20 of the blower 10
rises from the straight line f ₁ at the position of Y ₁ in the cold state to the position of Y ₂ , then these rotating bodies 10A, 11A
The axis of rises from the Y ₁ position to the Y ₂ position, but
Straight line _f3 is maintained similar to straight line _f1 , and stable operation can be maintained.

However, in reality, the bearing point 20 rises further than the position of Y ₂ , and in addition to the overall amount of rise Y ₂ - _{Y 1} = h ₁ , it also rises by h ₂ , so the rotating shaft system during operation becomes unstable, leading to an accident that may damage the bearings.

Therefore, in the present invention, in view of this point,
This was done with a focus on suppressing the increase in the shaft center by an amount _h2 that would cause an abnormality.

FIG. 3 explains a specific method of holding the shaft center of the rotating shafts 10A and 11A for the air blower shown in FIG. It is supported by support legs 27.

Here, the thermal elongation of the increase h ₁ in Figure 2 is
This is caused by the thermal elongation of the common base plate 25, and the thermal elongation of the support legs 27 becomes an abnormal elongation amount _h2 .

Therefore, the support legs 27 in this support device 14
A constant thermal expansion material, such as Invar material, is used for the rotation shafts 10A and 11A.
The state changes from the straight line f ₁ at the Y ₁ position to the straight line f ₃ at the Y ₂ position, and the axis is operated in a substantially straight line, and the axis can be ideally maintained.

Next, FIG. 4 shows a gas turbine power generation device which is an axial flow mechanical device according to a second embodiment of the present invention, in which 30 is a low-pressure compressor, 31 is a high-pressure compressor and a high-pressure turbine integrated. The gas generator 32 is a power turbine and is configured to simultaneously drive the low pressure compressor 30 and the generator 33.

The rotating shaft 31A of the gas generator 31 and the rotating shaft 32A of the output turbine 32 are supported by support devices at positions indicated by e, e', f, and g.
Each part of f and g is integrally formed with a gas turbine casing, parts e and g are supported against the ground, and parts e' and f are supported inside the casing.

Next, the rotating shaft 30A of the low pressure compressor 30 is h,
The rotating shaft 33A of the generator 33 is supported with respect to the ground by support legs j and k.

Further, the generator 33 and the low pressure compressor 30 are coupled through a shaft coupling 34, and the output turbine 32 and the low pressure compressor 30 are coupled through a shaft coupling 35.

Here, the arrow K indicates that each of the above-mentioned support devices consists of an oil film rigidity, a shaft support rigidity, and a damping system.

FIG. 5 shows the respective rotating shafts 31A, 32A, and
_This figure shows how the shaft centers of 30A and 33A are displaced in a conventional rotating shaft support device. f ₁ , the axis will be displaced from this state to a position of general average height Y ₂ in the operating state, and the bearing points 36, 38, 40, 4 of each support device will be
The axes at 2, 44, 46, and 48, which were on the straight line f ₁ at the Y ₁ position, are displaced due to thermal elongation during operation, and become 37, 39, 41, 43, and 4, respectively.
It shows how the numbers change to 5, 47, and 49.

Conventionally, each rotating shaft 31A, 32A, 30A, 33
In order for A to operate stably, it is necessary to keep the displacement within at least a certain allowable limit displacement ΔY. In other words, in the case of a rotating shaft system with multi-point support, if one support point experiences abnormal thermal elongation exceeding the allowable amount and becomes high, the surface pressure of the bearing at that high support point will increase. Moreover, the bearings on both sides of the raised bearing conversely reduce the surface pressure. This results in an abnormally high bearing surface pressure and, on the other hand, an abnormally low bearing surface pressure. As a result, the stability of the shaft support system may not be achieved, or the metal of the bearing may burn out due to abnormally high surface pressure.

In FIG. 5, for example, if the bearing 40 becomes abnormally high in temperature and rises to 41, the surface pressure on the bearing 41 will be high and the surface pressure on the bearings 39 and 41 will be low, resulting in burnout of the bearing or instability of the shaft system. cause a phenomenon.

For this reason, conventionally when assembling in a cold state,
The shaft center has been adjusted so that h ₃ , h ₄ and h ₅ of the bearing portion shown in FIG. 5, which are abnormally high, are lowered by that amount below the straight line f ₁ at the position of the shaft center Y ₁ . These situations are shown in FIGS. 5 to 5A. That is, FIG. 5A shows that in order to keep the displacement within the allowable displacement ΔY during operation, the abnormal heights h ₃ , h ₄ , and h ₅ need to be pushed downward during the cold state.

Therefore, in the present invention, by using a constant thermal expansion material, such as Invar material, only such abnormal axial center change amount is used to reduce the allowable limit displacement △Y.
Adjustments are made to keep it within this range.

If the axis holding method of the present invention is adopted, the hair ring points of each support device will be 37, 3 in FIG.
7', 39, 41, 43, 45, 47, 49 is the allowable limit displacement △Y even during operation.
(See FIGS. 5 and 5A).

That is, as shown in FIG. 6, 37, 37', 39, 41, 43, 45, 47,
49 are 37, 37″, 39′, 41′, respectively.
43, 45', 47, 49, which can be set as the range of allowable limit displacement ΔY. What is important is that the f ₁ line in FIG. 6 is a straight line, that is, the initial centering is straight and easy to work with, and the centering during rotor operation has an allowable limit displacement ΔY.

As described above, when the rotating shaft of an axial flow mechanical device is supported by a plurality of support devices, the present invention provides a permanent support leg of the support device that has a higher thermal expansion upward than other support devices. Since it is made of thermally expandable material,
It is now possible to maintain the axis of the rotating shaft within the allowable displacement from when it is cold and stationary to when it is operating, eliminating the need for many technical calculations and eliminating the need to adjust the axis when it is cold. become.

Further, there is a technical effect such that a cooling device for the support legs of the axial flow mechanical device is not required, and therefore, there is an advantage that axis center adjustment during disassembly and assembly is facilitated.

Furthermore, since the supporting leg cooling device is not required, operation and maintenance of the cooling device is not required, and the economical effect is also great.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a support device for a blower device in Embodiment 1 of the present invention, and FIG. 2 is a diagram showing the bearing points of each support device when the conventional shaft center holding method is applied to the blower device in FIG. Diagram showing the position during cooling and during operation, FIG. 3 is a schematic front view of the shaft center holding device of the blower device in FIG. 1, and FIG. 4 is a schematic side view of the gas turbine power generation device in Embodiment 2 of the present invention. figure,
5 and 5A are diagrams showing the positions of the bearing points of each support device in the cold state and during operation when the conventional shaft center holding method is applied to the gas turbine generator shown in FIG. FIG. 6 is a diagram showing the positions of the bearing points of each support device in a cold state and in operation when the present invention is applied to the gas turbine power generation device shown in FIG. 4. 10...Blower, 10A...Rotating shaft, 11...
Electric motor, 11A...Rotating shaft, 25...Common base plate,
26...Bracket, 27...Support leg, 30...
Low pressure compressor, 30A... Rotating shaft, 31... Gas generator, 31A... Rotating shaft, 32... Output turbine, 32A... Rotating shaft, 33... Generator, 3
3A...Rotation axis.

Claims (1)

[Claims] 1. When the rotating shaft of an axial flow mechanical device is supported by a plurality of support devices, the support legs of the support device, which has a higher thermal expansion upward than other support devices, are formed of a constant thermal expansion material. A method for holding the center of a rotating shaft of an axial flow mechanical device, characterized by: