SU1341518A1 - Method of determining the remaining life of electrical installation rotor - Google Patents

Abstract

The invention relates to a power system and m. used in power stations. The invention allows to increase the reliability of the obtained results when determining the resource of the rotor (P) of a steam turbine. For a fleet material P with a periodically removable surface layer, mechanical characteristics are determined. Specify the range of changes in the characteristics of the mechanical properties of P during actual operating time and t-re operation in damaged areas. Divide all P from the material of this class into groups with the difference of the maximum working mass between the groups being not less. The quantity P in the group must be at least 20. For each group P, select as the sample group the straight line sections of the steam lines, for example, fresh steam of hot reheat, the working temperature of which is not less than 20 ° ; C exceeds the maximum working temperature of this group P, and the mechanical properties of the samples are not higher than those of P last. (L 00 4: L 30

Description

113

The invention relates to a power system and can be used in power plants in determining the resource of a rotor-steam turbine.

The aim of the invention is to increase the reliability of the obtained results when determining the rotor resource. The method is carried out as follows.

On the rotor, periodically, for example, during repair, remove the surface layer. This makes it possible to prevent the development of macrocracks in the rotor and makes it possible to extend the life of the rotor until destruction in the bulk of the metal. For a fleet of rotors with a periodically removed surface layer, mechanical characteristics are determined; ki: yield strength, tensile strength, plasticity characteristics ((f7, -i 8, f), heat resistance characteristics (fr-g, S p) You are the most damaged areas of rotors during long-term operation. Such zones. These are the high-temperature zones of the structural concentrators and central cavities. They specify the range of changes in the indicated characteristics of the mechanical properties of the rotors during actual operating time and operating temperature in the damaged zones. All rotors of this class are divided into groups with a difference of Maximum operating temperatures

, ry between groups of at least

20 C. At the same time, the number of rotors in the group must be at least 20.

For each group of rotors, selected as a group of samples are straight sections of steam lines, for example, fresh steam, hot heating, the working (maximum at steady-state mode) temperature of which exceeds the maximum working temperature of this group by at least 20 ° C. rotors, and the mechanical properties of the samples are not higher than those of the latter. Testing of a group of samples is carried out in the process of operating loading of power plants at voltages averaged over the volume, exceeding the similar stresses in the rotor damage zones by no more than 20%. In this case, both in the rotors and in the samples, the amplitude of the tensile stresses is determined in a simple cycle, equivalent in damage to a complex operating cycle. This allows

0

5 0 5 o

182

take into account the entire historian of loading with the duration of testing a group of samples of not less than the service life of the rotors. The measurement of residual deformation is carried out periodically when the power plant is put into repair. When the maximum plasticity of the group of samples loaded at maximum temperature is reached, the residual life of the corresponding group of rotors is determined taking into account the accepted values of the safety factors. Having thus determined the life of the group of rotors operating under the most severe conditions, the residual life . lists, the volume of replacement groups of rotors throughout the park.

Example. Based on a summary of domestic data on the properties of rotors made of low-alloyed pearlite (CMP) steel P2M (P2MA), the following basic properties are determined in the operating temperature and stress range: yield strength G gj 360 MPa; tensile strength MPa; ultimate long-term strength} an at maximum temperature

g- i-i .r d -,

0

five

five

0

520 ° C rotor metal for the rotors of the K-200-130 JM3 turbine (the maximum tensile stresses on the bore of the medium-pressure rotor in stationary mode are 88 MPa) for 200 thousand hours is b a, 160 MPa. Ultimate plasticity S 25%, - (|) 75%.

The generalization of properties by direct pipelines from low-alloyed pearlite steel 12Х1МФ allows to determine the following values of similar Properties: yield strength G 240 MPa tensile strength (5 Hz 280 Mnaj tensile strength GQ 100 MPa, ultimate plasticity S 22%, (|) 72%.

As a group of rotors, for which the application of this method is considered, the medium pressure rotors (RSD) of the K-200-130 LMZ turbine were taken, the number of which reached 200 on thermal power plants. Averaged over the volume of voltage at the most the tension zone of the steam inlet does not exceed 50 MPa.

Steam pipelines of fresh steam (245–45 mm) are determined as a group of samples, in which the corresponding stresses exceed 55 MPa. With the Larson-Me parameter equal, the (ZO + lg tp) -10 playlist in the rotor and the image are obtained. what's the temperature

313415

the steam line is 1 565 + 273 838 K, and the rotor temperature is 1 520 + 273 793 K, a ratio that determines the time until the rotor is destroyed. At the same time, it was assumed that the voltages in the rotor and the steam line are the same in volume. This assumption goes to the durability margin. The time before the destruction of the rotor is determined from the ratio

ten

T, / T (20 + lg j,) / (20 + lgtp),

,

where t

P

P, .R p

rotor steam line temperature;

time before the destruction of the rotor, the steam line.

Having assumed the safety factor n over time until the destruction of pg 10, it is obtained that the resource of safe operation of the rotor park is more than 3.5 times greater than the life of the samples.

The measurement of residual deformation in the steam line :: s when implementing the method is carried out in accordance with the current instructions for controlling the metal of boilers, turbines and pipelines every 25,000 hours of operation after 100 thousand hours of operation. The value of the result obtained is determined as follows. According to the resultant L.Povkhan 4428/46

Compiled by A. Bulynko Tehred A. Kravchuk

Korrek Podpi

Circulation 776 VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

18 .

there conventional research obtained that after 300 thousand h one should expect a significant softening of the material of the considered rotor fleet with a loss of their working capacity.

The determination of the rotor resource by the described method will allow to obtain reliable results on the residual resource, and, consequently, to extend the resource of safe operation of the rotor fleet.

Claims (1)

15 claims The method of determining the residual life of the rotor of a power plant with a periodically removed surface layer by testing a group of samples from the material of the same class as the rotor, and at temperatures exceeding the maximum operating temperature of the rotor, and changing when testing residual deformation to achieve its maximum value, differing from that, in order to increase the reliability of the results obtained, as samples. use straight sections of cylinder steam lines with mechanical properties not higher than the mechanical properties of the rotor. Proofreader A.Zimokosov Subscription