METHOD FOR CHECKING A CONTINUOUS-FLOW MACHINE

Abstract

A method for checking a steam turbine, wherein a first operating variable and a second operating variable are determined, wherein a correlation between the first and second operating variable prevails, and a confidence band having an upper maximum value and a lower minimum value is created, wherein a notification is generated as long as the second operating variable is outside the confidence band during operation.

Claims

1. A method for monitoring a continuous-flow machine, comprising: in a first phase, measuring a first operating property and a second operating property of the continuous-flow machine and associating and storing a value of the second operating property with each value of the first operating property, and determining an upper maximum value of the second operating property and a lower minimum value of the second operating property for each value of the first operating property, in a second phase following the first phase, determining the first operating property and second operating property, and generating a notification when the value of the second operating property falls below the lower minimum value or exceeds the upper maximum value, wherein the continuous-flow machine has a sealing steam system with a sealing steam controller and a controller output of the sealing steam controller is used as the first operating property, and wherein the continuous-flow machine has a high-pressure turbine section and a high-pressure wheel chamber pressure is used as the second operating property.

2. The method as claimed in claim 1, wherein the first phase takes place while the continuous-flow machine is being put into service.

3. The method as claimed in claim 1, wherein the continuous-flow machine comprises a steam turbine.

4. The method as claimed in claim 1, wherein the continuous-flow machine has a sealing steam system with a sealing steam controller and a sealing steam pressure is used as the first operating property.

5. The method as claimed in claim 1, wherein the continuous-flow machine has a high-pressure and medium-pressure turbine section arranged in a common outer housing and a pressure of an exhaust steam of the medium-pressure turbine section is used as the second operating property.

6. The method as claimed in claim 1, wherein the upper maximum value of the second operating property and the lower minimum value of the second operating property are stored in a confidence band.

7. The method as claimed in claim 1, wherein the upper maximum value of the second operating property and the lower minimum value of the second operating property are determined from different start-up instances of the continuous-flow machine.

8. The method as claimed in claim 1, wherein the second phase takes place during an operating phase.

9. The method as claimed in claim 1, wherein the values determined in the second phase are determined for the first operating property and the second operating property by a measurement system.

10. A system for monitoring a continuous-flow machine, wherein the system is adapted to perform the method as claimed in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Reference is made to the relevant prior art with regard to supplements to the teachings directly observable in the drawings, in which:

[0024] The FIGURE shows a correlation between a first operating property and a second operating property.

DETAILED DESCRIPTION OF INVENTION

[0025] The invention relates to a method for monitoring a steam turbine.

[0026] A steam turbine as an embodiment of a continuous-flow machine has essentially an outer housing and a rotor mounted rotatably inside the outer housing. An inner housing is generally arranged around the rotor. Steam turbines employed in steam-fired power plants generally have a high-pressure turbine section, a medium-pressure turbine section, and a low-pressure turbine section. There are embodiments in which a high-pressure turbine section and a medium-pressure turbine section are arranged inside a common housing.

[0027] In the method according to the invention for monitoring the steam turbine, in a first phase which takes place whilst the machine is being put into service, a first operating property and a second operating property of the steam turbine are measured. A value for the second operating property is associated with each value of the first operating property. The data established in this way, which are also referred to as the footprint, are stored.

[0028] In a further step, an upper maximum value for the second operating property and a lower minimum value for the second operating property are determined for each value of the first operating property. This is also referred to as the confidence band.

[0029] In a second phase following the first phase, which takes place during the operating phase, the first operating property and the second operating property are continuously determined, wherein this can be effected by a measurement system. The values determined in this way are compared with one another and as soon as the value of the second operating property falls below the lower value or exceeds the upper value, a notification is generated.

[0030] The FIGURE shows the correlation between a first operating property 1 and a second operating property 2. A first operating property 1 of the controller output of the sealing steam controller is plotted on the X-axis. Alternatively, a first operating property 1 of the sealing steam pressure can be used.

[0031] In the curve 3 shown in the FIGURE, the controller output of the controller is given as a percentage on the X-axis. The range between 0% and 100% is accordingly given for the controller output. A second operating property 2 corresponding to the first operating property 1 is plotted on the Y-axis, and to be precise the high-pressure wheel chamber pressure. Alternatively, the pressure of the exhaust steam of the medium-pressure turbine section can be used where the steam turbine has a high-pressure and medium-pressure turbine section arranged in a common outer housing. The curve 3 shows the correlation between the first operating property 1 and the second operating property 2.

[0032] Furthermore, in the FIGURE a lower minimum value 4 and an upper maximum value 5 are given, by way of example, for the value 50% of the first operating property 1. The curve 3 is thus, as it were, framed between a lower minimum value 4 and an upper maximum value 5. This is represented by the dashed line below the curve 3 and the dashed line above the curve 3. The dashed lines thus show a confidence band.

[0033] During operation, the operating property 1 and the operating property 2 are measured and, if the second operating property 2 is above the upper maximum value 5 or below the lower minimum value 4, a notification is generated. By means of the notification, notice is given of a change in the shaft gland seal clearance and hence an indication that the gland seal clearance should be monitored as soon as possible in order, for example, to prevent rubbing.

[0034] Although the invention has been illustrated and described in detail by means of the preferred exemplary embodiment, the invention is not limited by the examples disclosed and other variants can be derived by a person skilled in the art without going beyond the protective scope of the invention.