Method for determining performance degradation of gas turbine based on operating data

Abstract

The invention relates to a method for determining performance degradation of a gas turbine based on operating data, which comprises the following steps of: selecting a gas turbine to stably operate under a rated working condition, and obtaining a difference value of average rotating speeds of rotors of a high-pressure compressor corresponding to actual power under the rated working condition at the same inlet air temperature at two moments t1 and t2 of the gas turbine operating for a period of time t2; and according to the relation between the thermal efficiency value change and the rotating speed difference value of the high-pressure air compressor, the rotating speed difference value of the high-pressure air compressor serves as an index of performance degradation. When the rotating speed difference value of the high-pressure compressor exceeds a certain value, the through-flow part needs to be cleaned. And after cleaning, the rotating speed difference value of the still existing high-pressure compressor is the unrecoverable performance number. The method adopts real-time operation data, does not need to correct various parameters, is easy to operate and good in practicability, and has important significance on operation of the gas turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbines, and in particular to a method for determining the performance degradation of a gas turbine based on operating data. Background Art

[0002] Due to advantages such as a compact structure layout, good fuel economy indicators, high thermal efficiency, good reliability, and long service life, gas turbines are widely used in fields such as ship power and power generation on offshore oil platforms, becoming a representative of the new generation of core power.

[0003] At present, the performance indicators of gas turbines mainly rely on the thermal efficiency under rated conditions. However, the measurement of thermal efficiency is affected by the change in the lower calorific value of fuel, and at the same time, due to special operating environments (such as gas turbines for offshore oil platforms and ships), there are certain limitations in measuring the thermal efficiency.

[0004] To determine the performance degradation of a gas turbine, such as determining the timing of cleaning the flow path, it is impractical to calculate the thermal efficiency at all times. A more convenient determination method is needed. Summary of the Invention

[0005] The applicant of the present invention aims at the above-mentioned disadvantages in the existing production technology and provides a method for determining the performance degradation of a gas turbine based on operating data, which only uses real-time operating data to determine the performance degradation nodes of each individual gas turbine.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for determining the performance degradation of a gas turbine based on operating data, which selects the average value of the high-pressure compressor rotor speed under expected conditions, and obtains the rated-condition thermal efficiency of the gas turbine according to the linear numerical relationship between the average value and the average value of different inlet air temperatures;

[0008] According to the difference in the average value of the high-pressure compressor rotor speed, obtain the linear relationship between the thermal efficiency and the average difference, and use the average difference as an indicator of performance degradation;

[0009] When the average difference during real-time operation exceeds the expected value, the flow path should be cleaned; the average difference remaining after cleaning is the non-recoverable performance number.

[0010] As a further improvement of the above technical solution:

[0011] It includes the following steps:

[0012] Step 1: Select the operation period after the gas turbine operates stably under rated conditions for a period of time, and select the average value of the high-pressure compressor rotor speed corresponding to the actual power output under the rated condition of the hydraulic dynamometer at different average inlet air temperatures.

[0013] Step 2: Obtain the linear numerical relationship between the average value of different inlet air temperatures and the average value of the high-pressure compressor rotor speed.

[0014] Step 3: Calculate the rated condition thermal efficiencies η1 and η2 corresponding to the gas turbine at time node t1 and time node t2 after running for a period of time respectively.

[0015] Step 4: Through Step 1 and Step 2, obtain the difference Δn2 in the average value of the high-pressure compressor rotor speed corresponding to the gas turbine at t1 and t2 under the same inlet air temperature condition.

[0016] Step 5: According to the linear relationship between the difference between the thermal efficiencies η1 and η2 and Δn2, use Δn2 as an indicator of performance degradation.

[0017] Step 6: When the Δn2 during real-time operation exceeds the expected value, the flow path should be cleaned; after cleaning, the remaining Δn2 is the non-recoverable performance number.

[0018] In Step 1, the error range of the actual output power of the hydraulic dynamometer under rated conditions is: error ±1KW.

[0019] The value of the average inlet air temperature is accurate to two decimal places.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a method for determining the performance degradation of a three-shaft gas turbine based on operating data. This method selects the gas turbine to operate stably under rated conditions, and obtains the difference in the high-pressure compressor rotor speed corresponding to the actual output power under rated conditions at two moments, t1 and t2 after running for a period of time t2, of the gas turbine under the same inlet air temperature. According to the relationship between the change in the thermal efficiency value and the difference in the high-pressure compressor speed, the above-mentioned difference in the high-pressure compressor speed is used as an indicator of performance degradation.

[0022] When the difference in the high-pressure compressor speed exceeds a certain value, the flow path should be cleaned. After cleaning, the remaining difference in the high-pressure compressor speed is the non-recoverable performance number. This method uses real-time operating data, does not require correction of various parameters, is easy to operate, has good practicability, and is of great significance to the operation of the gas turbine. Description of the Drawings

[0023] Figure 1 It is a linear relationship diagram of the intake air temperature and the high pressure speed. Detailed Embodiment

[0024] The following combines the drawings to illustrate the detailed embodiment of the present invention.

[0025] The detailed steps of applying the method of the present application to a specific working condition are as follows:

[0026] Working background: A certain three-shaft gas turbine contains a low-pressure compressor, a high-pressure compressor, and a power turbine; this three-shaft gas turbine operates continuously, and a hydraulic dynamometer is used to measure the actual power output.

[0027] Step 1: Select the average values of the rotational speeds of the high-pressure compressor rotor at the actual power output under the rated conditions of the hydraulic dynamometer at different inlet air temperatures after the gas turbine has operated stably for 5 minutes under the rated conditions in different operating periods. The average values are shown in Tables 1, 2, 3, and 4 below.

[0028] Among them, the selected operating periods include:

[0029] The operating period of 0 - 30 hours, the operating period of 500 - 530 hours, the operating period of 1030 - 1050 hours, and the operating period of 1050 - 1070 hours.

[0030] Among them, the operating period of 1050 - 1070 hours is the period after flow path cleaning.

[0031] The rated condition for each period is 60000 KW; the average value of the air temperature at each inlet is taken; the error range of the actual power output under the rated condition of the hydraulic dynamometer is ±1 KW.

[0032] Table 1 Different inlet air temperatures and high-pressure compressor speeds at the rated power during the operating period of 0 - 30 hours

[0033]

[0034] Table 2 Different inlet air temperatures and high-pressure compressor speeds at the rated power during the operating period of 500 - 530 hours

[0035]

[0036]

[0037] Table 3 Different inlet air temperatures and high-pressure compressor speeds at the rated power during the operating period of 1030 - 1050 hours

[0038]

[0039] Table 4 Different inlet air temperatures and high-pressure compressor speeds at the rated power during the operating period of 1050 - 1070 hours (after flow path cleaning)

[0040]

[0041]

[0042] Step 2: According to the above Table 1, Table 2, Table 3, and Table 4, obtain the linear numerical relationship between the average value of the inlet air temperature at different time periods and the average value of the high-pressure compressor rotor speed, as Figure 1 shown.

[0043] Step 3: Calculate the corresponding rated condition thermal efficiencies η1 and η2 of the gas turbine at time t1 and after running for a period of time t2.

[0044] During the operation period of 0 - 30 hours, through calculation, the rated condition thermal efficiency η1 of the gas turbine is 40.5%.

[0045] During the operation period of 500 - 530 hours, through calculation, the rated condition thermal efficiency η2 of the gas turbine is 40.2%.

[0046] The above calculations are all conventional methods in this industry, that is, the thermal efficiency calculation method. For details, please refer to the Shipbuilding Industry Standard of the People's Republic of China, "Data Processing Method for Thermal Performance Test of Ship Gas Turbines".

[0047] Step 4: Through Step 1 and Step 2, obtain the average value difference Δn2 = 52 of the high-pressure compressor rotor speed corresponding to 15°C under the same inlet air temperature during the operation period of 0 - 30 hours and the operation period of 500 - 530 hours of the gas turbine, as shown in Table 5.

[0048] Table 5 Rotational Speed Difference and Thermal Efficiency in Different Operation Periods

[0049]

[0050]

[0051] Step 5: According to the linear relationship between the difference of the thermal efficiencies η1 and η2 and Δn2, take Δn2 as an indicator of performance degradation. According to the linear relationship between Δn2 and Δη, that is:

[0052] Δη / Δn2 = (40.5 - 40.2) / 52 = 0.00577,

[0053] When Δn2 is 1, it indicates that the thermal efficiency of the unit drops by 0.00577%.

[0054] Step 6: According to the linear relationship between Δn2 and Δη in Step 5, obtain that the rated condition thermal efficiency of the unit during the operation period of 1030 - 1050 hours is = 40.2 - (13099 - 13060) * 0.00577 = 39.98. According to the operation requirements of this unit, when the thermal efficiency drops by 0.5% or Δn2 ≥ 0.5 / 0.00577 = 86, the flow passage part should be cleaned.

[0055] Therefore, cleaning was carried out after 1050 hours of operation. By calculation, the high-pressure speed corresponding to 15°C during the period of 1050 - 1070 hours of operation (after through-flow cleaning) was 13019. The difference between this speed and the initial speed of 13008 during operation was 11. By calculation, η for the 1050 - 1070 hours period = 40.5 - 0.00577 * 11 = 40.44. That is, it is deduced that compared with the initial thermal efficiency after cleaning, the thermal efficiency decreased by 0.00577 * 11 = 0.063 (%). Both Δn2 = 11 can characterize that this part is the part of performance decline that cannot be recovered.

[0056] Based on the operating data of the gas turbine, the timing of the performance decline of the gas turbine can be deduced and calculated in this application; no operations such as parameter correction are required, with lower difficulty and strong practicability.

[0057] The above description is an explanation of the present invention, not a limitation of the invention. The scope defined by the present invention can be seen in the claims. Any form of modification can be made within the protection scope of the present invention.

Claims

1. A method for determining the performance degradation of a gas turbine based on operating data, characterized in that, Select the average value of the high-pressure compressor rotor speed under the expected conditions, and obtain the rated-condition thermal efficiency of the gas turbine according to the linear numerical relationship between this average value and the average value of different inlet air temperatures; Obtain the linear relationship between the thermal efficiency and this average difference according to the average difference of the high-pressure compressor rotor speeds, and use this average difference as an indicator of performance degradation; When the average difference during real-time operation exceeds the expected value, the flow path part should be cleaned; The average difference that still exists after cleaning is the non-recoverable performance number.

2. The method for determining the performance degradation of a gas turbine based on operating data according to claim 1, wherein It includes the following steps: Step 1: Select the operation period after the gas turbine operates stably under the rated conditions for a period of time, and select the average value of the high-pressure compressor rotor speed corresponding to the actual output power under the rated conditions of the hydraulic dynamometer at different average values of the inlet air temperature; Step 2: Obtain the linear numerical relationship between the average value of different inlet air temperatures and the average value of the high-pressure compressor rotor speed; Step 3: Calculate the rated-condition thermal efficiencies η1 and η2 corresponding to the time node t1 of the gas turbine and the time node t2 after operating for a period of time respectively; Step 4: Through Step 1 and Step 2, it is obtained that when the gas turbine is at t1 and t2 under the same inlet air temperature condition, the difference in the average value of the high-pressure compressor rotor speed Δ n 2 , Step 5: According to the linear relationship between the difference between the thermal efficiencies η1 and η2 and Δn2, use Δn2 as an indicator of performance degradation; Step 6: When the Δn2 during real-time operation exceeds the expected value, the flow path part should be cleaned; after cleaning, the remaining Δn2 is the non-recoverable performance number.

3. The method for determining the performance degradation of a gas turbine based on operation data according to claim 2, wherein: In Step 1, the error range of the actual output power under the rated conditions of the hydraulic dynamometer is: error ±1KW.

4. The method for determining the performance degradation of a gas turbine based on operating data according to claim 2, characterized in that: The value of the average inlet air temperature is accurate to two decimal places.

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