Method for determining contamination on air compressor by using rotating speed of low-pressure air compressor when gas turbine works in marine environment

Abstract

The present invention relates to a method for determining contamination on an air compressor by using a rotating speed of a low-pressure air compressor when a gas turbine works in a marine environment. The method comprises: after a gas turbine undergoes factory commissioning and operates for a period of time, a rotating speed-based contamination determination area in which the corrected rotating speed of a high-pressure air compressor and the corrected rotating speed of a low-pressure air compressor in an approximately rated working condition have a linear relationship is obtained; the corrected rotating speed of the high-pressure air compressor in the middle area is selected as a reference to correct the rotating speed difference of the low-pressure air compressor as a contamination determination basis, on the basis of a relationship between a thermal efficiency value change and the corrected rotating speed difference of the low-pressure air compressor, when a thermal efficiency value is reduced to a certain value, cleaning needs to be performed, and thus, the corrected rotating speed change value of the low-pressure air compressor when cleaning is needed is obtained. The method has clear logic and is easily implemented, and has important significant on operation of the gas turbine.

Description

Method for determining compressor fouling using low-pressure compressor speed in gas turbines operating in marine environments Technical Field

[0001] The present invention relates to the technical field of gas turbine overhaul, and in particular to a method for determining compressor contamination by utilizing the rotational speed of a low-pressure compressor when the gas turbine is working in a marine environment. Background Art

[0002] Gas turbines are widely used in fields such as ship propulsion and offshore oil platform power generation.

[0003] Currently, gas turbine cleaning is primarily based on efficiency or accumulated operating time. However, thermal efficiency measurement is affected by the accuracy of power measurement, fuel lower heating value testing, and fuel flow measurement. Furthermore, the unique operating environments of gas turbines used in offshore oil platforms and ship propulsion impose certain limitations on accurate thermal efficiency measurement. During gas turbine operation, power output fluctuates based on real-time demand, with no discernible regularity. Therefore, performing flow cleaning based on accumulated operating time at fixed intervals is unscientific. Summary of the Invention

[0004] In response to the shortcomings of the above-mentioned existing production technology, the applicant provides a reasonable method for determining compressor contamination using low-pressure speed when the gas turbine is operating in a marine environment based on the salt spray deposition characteristics of the three-rotor gas turbine compressor in the marine environment. The method is suitable for determining the contamination of the compressor of each gas turbine of this type.

[0005] The technical solutions adopted in the present invention are as follows:

[0006] A method for determining compressor contamination using low-pressure compressor speed in a gas turbine operating in a marine environment comprises the following steps:

[0007] Step 1: During both factory operation and after a period of operation, the gas turbine is operated at a rated power level of 10% of the rated power as the first gear. The low-pressure compressor speed and high-pressure compressor speed of each operating condition are corrected for atmospheric conditions, total intake pressure loss, and exhaust static pressure loss to obtain corresponding correction values. Simultaneously, the thermal efficiency of the rated operating condition is measured at the initial operation and after a period of operation.

[0008] Step 2: Based on the relationship between the corrected low-pressure compressor speed and the corrected high-pressure compressor speed, a pollution determination speed region in which the corrected high-pressure compressor speed and the corrected low-pressure compressor speed have a linear relationship is obtained;

[0009] Step 3: In the pollution judgment area obtained above, select the corrected high-pressure compressor speed in the middle area as the benchmark and calculate the corresponding corrected low-pressure compressor speed; based on the relationship between the change in thermal efficiency value and the difference in corrected low-pressure compressor speed, when the thermal efficiency value drops below the expected value, cleaning should be carried out, and then the corrected low-pressure compressor speed change value when cleaning is required is obtained.

[0010] A method for determining compressor contamination using low-pressure compressor speed in a gas turbine operating in a marine environment includes the following steps:

[0011] Before the gas turbine was delivered, it was operated at full power, which means it was operated at 10% of the rated power.

[0012] After that, the machine was run for a period of time to measure the thermal efficiency. The operating conditions were based on 10% of the rated power as one gear, and the machine was run from no-load to full rated power.

[0013] Step 1: Start the gas turbine operation at the first gear of 10% rated power and operate it at full working condition. After factory operation and a period of operation, the low-pressure compressor speed and high-pressure compressor speed of each working condition are adjusted to the same standard according to the prescribed reference atmospheric conditions, inlet total pressure loss and exhaust static pressure loss. The formula is as follows: n Z =n T ×(1+D' i +D” i ) (2)

[0014] Where: n, n T 、n z The measured rotor speed, the rotor speed corrected to the specified reference atmospheric conditions, and the speed corrected according to the intake and exhaust loss deviation are respectively, r / min; T1 is the measured atmospheric temperature, K; D′ i 、D″ i The deviation correction coefficients of intake loss and exhaust loss are calculated respectively. Through thermal efficiency calculation, after running for several hours, the thermal efficiency decreases by η compared with the factory, and the corrected high-pressure compressor speed and the corrected low-pressure compressor speed after factory operation and several hours of operation are obtained.

[0015] Through thermal efficiency calculation, after running for several hours, the thermal efficiency decreases by η compared with the factory, and the corrected high-pressure compressor speed and the corrected low-pressure compressor speed after factory operation and several hours of operation are obtained.

[0016] Step 2: Based on the relationship between the corrected low-pressure compressor speed and the corrected high-pressure compressor speed, a pollution judgment speed region is obtained in which the corrected high-pressure compressor speed close to the rated operating condition has a linear relationship with the corrected low-pressure compressor speed.

[0017] According to the factory-corrected speed and the corrected speed after running for several hours, it can be seen that there is a linear area between the factory and after running for several hours. Referring to the linear area, the corrected high-pressure compressor speed is in the range (a~b). Under the same reduced high-pressure speed value, there is a fixed difference between the reduced low-pressure compressor speeds. Therefore, the range (a~b) where the reduced high-pressure speed value is located is the compressor contamination judgment area.

[0018] Step 3: In the pollution judgment area (a-b) obtained above, select the corrected high-pressure compressor speed in the middle area as the benchmark, that is, the benchmark is (a+b) / 2,

[0019] In the factory state, according to the curve relationship, when the high-pressure compressor speed is corrected to (a+b) / 2, the corresponding reduced low-pressure compressor speed is recorded as n 出厂 ,

[0020] After running for several hours, according to the curve relationship, when the high-pressure compressor speed is corrected to (a+b) / 2, the corresponding reduced low-pressure compressor speed is recorded as n 运行 ,

[0021] Since it has been known in step 1 that the thermal efficiency has decreased by η compared to the factory setting after several hours of operation, when the high-pressure compressor speed is corrected to (a+b) / 2, the reduced value of the low-pressure compressor speed is n 出厂 -n 运行 ,

[0022] According to the reference operation specification, when the thermal efficiency of the gas turbine drops by 0.25%, the flow part should be cleaned. According to the relationship between the thermal efficiency reduction value and the reduced value of the low-pressure compressor speed, when the thermal efficiency of the gas turbine drops by 0.25%, the reduced value of the low-pressure compressor speed should be recorded as n 下降 ,

[0023] That is, the low-pressure compressor speed is: n 出厂 -n 下降 When cleaning, it should be carried out through the flow,

[0024] Then the subsequent unit operation is determined, and the corrected high-pressure compressor speed is (a+b) / 2, and the corresponding corrected low-pressure compressor speed is: n 出厂 -n 下降 When cleaning, flow cleaning should be carried out.

[0025] Atmospheric conditions are: atmospheric pressure 101325Pa, atmospheric temperature 27℃.

[0026] In step 3, the corrected high-pressure compressor speed in the middle region is selected as a reference, specifically: the middle value of the two end point values ​​of the pollution judgment region is taken as the reference.

[0027] The beneficial effects of the present invention are as follows:

[0028] Based on the salt spray deposition characteristics of gas turbine compressors operating in marine environments, this method, after factory operation and a period of operation, derives a contamination determination speed range where a linear relationship exists between the corrected high-pressure compressor speed and the corrected low-pressure compressor speed near rated operating conditions. By selecting the corrected high-pressure compressor speed in the intermediate range as a benchmark and the corrected low-pressure compressor speed difference as the basis for contamination determination, the relationship between the change in thermal efficiency and the corrected low-pressure compressor speed difference indicates that cleaning should be performed when the thermal efficiency decreases by a certain value. This method then derives the corrected low-pressure compressor speed change value at which cleaning is indicated. This method is logically clean and easy to operate, and is of great significance to gas turbine operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a flow chart of the present invention.

[0030] FIG2 is a diagram showing the factory-corrected speed and the 600-hour-running corrected speed in the steps of the present invention.

[0031] FIG3 is a diagram of the pollution judgment area in the steps of the present invention.

[0032] FIG4 is a diagram showing the reduced rotational speed after through-flow cleaning according to the present invention. DETAILED DESCRIPTION

[0033] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0034] A method for determining compressor contamination using low-pressure compressor speed in a gas turbine operating in a marine environment comprises the following steps:

[0035] Step 1: During both factory operation and after a period of operation, the gas turbine is operated at a rated power level of 10% of the rated power as the first gear. The low-pressure compressor speed and high-pressure compressor speed of each operating condition are corrected for atmospheric conditions, total intake pressure loss, and exhaust static pressure loss to obtain corresponding correction values. Simultaneously, the thermal efficiency of the rated operating condition is measured at the initial operation and after a period of operation.

[0036] Step 2: Based on the relationship between the corrected low-pressure compressor speed and the corrected high-pressure compressor speed, a pollution determination speed region in which the corrected high-pressure compressor speed and the corrected low-pressure compressor speed have a linear relationship is obtained;

[0037] Step 3: In the pollution judgment area obtained above, select the corrected high-pressure compressor speed in the middle area as the benchmark and calculate the corresponding corrected low-pressure compressor speed; based on the relationship between the change in thermal efficiency value and the difference in corrected low-pressure compressor speed, when the thermal efficiency value drops below the expected value, cleaning should be carried out, and then the corrected low-pressure compressor speed change value when cleaning is required is obtained.

[0038] The following are examples of practical applications of the above theoretical methods:

[0039] A gas turbine was delivered from the factory in February 2023. Prior to delivery, it was operated at full power (10% rated power per gear). In May 2023, it ran for 600 hours, including thermal efficiency measurements. The operating conditions were based on actual power output, ranging from 10% rated power per gear to 50% rated power or higher.

[0040] Step 1: After the gas turbine is initially operated and undergoes the first throughflow purge, operate at full power at various operating levels, starting with 10% of rated power and continuing through 50% of rated power. The low-pressure compressor speed and high-pressure compressor speed at various operating levels, both at factory operation and after a period of operation, are corrected to the same standard using the specified reference atmospheric conditions (atmospheric pressure 101325 Pa, atmospheric temperature 27°C), inlet total pressure loss, and exhaust static pressure loss. The formula is shown below. n Z =n T ×(1+D' i +D” i ) (2)

[0041] Where: n, n T 、n z The measured rotor speed, the rotor speed corrected to the specified reference atmospheric conditions, and the speed corrected according to the intake and exhaust loss deviation are respectively, r / min; T1 is the measured atmospheric temperature, K; D′ i 、D″ i The correction coefficients for intake loss and exhaust loss deviation are respectively. The correction method and thermal efficiency measurement method are detailed in the People's Republic of China Shipbuilding Industry Standard "Data Processing Method for Thermal Performance Test of Ship Gas Turbines" (CB 20429-2018).

[0042] Through thermal efficiency calculation, after 600 hours of operation, the thermal efficiency dropped by 0.19% compared with the factory.

[0043] The corrected high-pressure compressor speed and corrected low-pressure compressor speed after factory operation and 600 hours of operation are obtained, as shown in Figure 2 below.

[0044] Step 2: Based on the relationship between the corrected low-pressure compressor speed and the corrected high-pressure compressor speed, a pollution judgment speed region is obtained in which the corrected high-pressure compressor speed close to the rated operating condition has a linear relationship with the corrected low-pressure compressor speed.

[0045] Figure 3 shows that a linear region exists between factory settings and after 600 hours of operation. As shown in Figure 3, the corrected high-pressure compressor speed is in the 0.944-0.968 range. At the same reduced high-pressure speed value, there is a fixed difference between the reduced low-pressure compressor speed. Therefore, the 0.944-0.968 range, where the reduced high-pressure speed value lies, represents the compressor contamination determination region.

[0046] Step 3: In the pollution judgment range (0.944-0.968) obtained above, select the corrected high-pressure compressor speed in the middle range as the benchmark, that is, (0.944+0.968) / 2=0.956.

[0047] In the factory state, according to the curve relationship, when the high-pressure compressor speed is corrected to 0.956, the corresponding equivalent low-pressure compressor speed is 0.911.

[0048] After 600 hours of operation, according to the curve relationship, when the high-pressure compressor speed is corrected to 0.956, the corresponding equivalent low-pressure compressor speed is 0.904.

[0049] From the first step, it can be seen that after 600 hours of operation, the thermal efficiency decreases by 0.19% compared with the factory setting. When the high-pressure compressor speed is corrected to 0.956, the reduced value of the low-pressure compressor speed is 0.911-0.904=0.007.

[0050] The operating specifications stipulate that when the gas turbine thermal efficiency drops by 0.25%, a throughflow cleaning should be performed. Based on the relationship between the thermal efficiency reduction and the reduced low-pressure compressor speed, when the gas turbine thermal efficiency drops by 0.25%, the reduced low-pressure compressor speed should drop by 0.25% / 0.19%*0.007=0.009, or when the reduced low-pressure compressor speed is 0.911-0.009=0.902, at which point throughflow cleaning should be performed. This further determines that for subsequent unit operation, throughflow cleaning should be performed when the corrected high-pressure compressor speed is 0.956, corresponding to an reduced low-pressure compressor speed of 0.911-0.009=0.902.

[0051] According to operating parameters, when the unit reached 700 hours of operation, the corrected high-pressure compressor speed was 0.956, corresponding to an equivalent low-pressure compressor speed of 0.903, reaching 0.902. Throughflow cleaning was then performed, and the equivalent speed values ​​after cleaning are shown in Figure 4. In the contamination assessment range (0.944-0.968), the equivalent low-pressure compressor speed returned to the factory value, demonstrating the cleaning effect.

[0052] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any modifications may be made within the scope of protection of the present invention.

Claims

1. A method for determining compressor contamination using low-pressure compressor speed in a gas turbine operating in a marine environment, characterized in that: The steps include: Step 1: During both factory operation and after a period of operation, the gas turbine is operated at a rated power level of 10% of the rated power as the first gear. The low-pressure compressor speed and high-pressure compressor speed of each operating condition are corrected for atmospheric conditions, total intake pressure loss, and exhaust static pressure loss to obtain corresponding correction values. Simultaneously, the thermal efficiency of the rated operating condition is measured at the initial operation and after a period of operation. Step 2: Based on the relationship between the corrected low-pressure compressor speed and the high-pressure compressor speed, a pollution judgment speed region in which the corrected high-pressure compressor speed and the corrected low-pressure compressor speed have a linear relationship is obtained; Step 3: In the pollution judgment area obtained above, select the corrected high-pressure compressor speed in the middle area as the benchmark and calculate the corresponding corrected low-pressure compressor speed; based on the relationship between the change in thermal efficiency value and the difference in corrected low-pressure compressor speed, when the thermal efficiency value drops below the expected value, cleaning should be carried out, and then the corrected low-pressure compressor speed change value when cleaning is required is obtained.

2. A determination process using the method of determining compressor contamination by using the low-pressure compressor speed when the gas turbine is operating in a marine environment according to claim 1, characterized in that: The steps include: Before the gas turbine was delivered, it was operated at full power, which means it was operated at 10% of the rated power. After that, the machine was run for a period of time to measure the thermal efficiency. The operating conditions were based on 10% of the rated power as one gear, and the machine was run from no-load to full rated power. Step 1: Start the gas turbine operation at the first gear of 10% rated power and operate it at full working condition. After factory operation and a period of operation, the low-pressure compressor speed and high-pressure compressor speed of each working condition are adjusted to the same standard according to the prescribed reference atmospheric conditions, inlet total pressure loss and exhaust static pressure loss. The formula is as follows: n Z =n T ×(1+D′ i +D″ i ) (2) Where: n, n T 、n z The measured rotor speed, the rotor speed corrected to the specified reference atmospheric conditions, and the speed corrected according to the intake and exhaust loss deviation are respectively, r / min; T1 is the measured atmospheric temperature, K; D′ i 、D″ i The deviation correction coefficients of intake loss and exhaust loss are calculated respectively. Through thermal efficiency calculation, after running for several hours, the thermal efficiency decreases by η compared with the factory, and the corrected high-pressure compressor speed and the corrected low-pressure compressor speed after factory operation and several hours of operation are obtained. Step 2: Based on the relationship between the corrected low-pressure compressor speed and the corrected high-pressure compressor speed, a pollution judgment speed region is obtained in which the corrected high-pressure compressor speed close to the rated operating condition has a linear relationship with the corrected low-pressure compressor speed. According to the factory-corrected speed and the corrected speed diagram after several hours of operation, it can be seen that there is a linear area between the factory and several hours of operation. Referring to the linear area, the corrected high-pressure compressor speed is in the range (a~b). There is a fixed difference between the reduced low-pressure compressor speed corresponding to the same reduced high-pressure speed value. Therefore, the range (a~b) where the reduced high-pressure speed value is located is the compressor contamination judgment area. Step 3: In the pollution judgment area (a-b) obtained above, select the corrected high-pressure compressor speed in the middle area as the benchmark, that is, the benchmark is (a+b) / 2, In the factory state, according to the curve relationship, when the high-pressure compressor speed is corrected to (a+b) / 2, the corresponding reduced low-pressure compressor speed is recorded as n 出厂 , After running for several hours, according to the curve relationship, when the high-pressure compressor speed is corrected to (a+b) / 2, the corresponding reduced low-pressure compressor speed is recorded as n 运行 , Since it has been known in step 1 that the thermal efficiency has decreased by η compared to the factory setting after several hours of operation, when the high-pressure compressor speed is corrected to (a+b) / 2, the reduced value of the low-pressure compressor speed is n 出厂 -n 运行 , According to the reference operation specification, when the thermal efficiency of the gas turbine drops by 0.25%, the flow part should be cleaned. According to the relationship between the thermal efficiency reduction value and the reduced value of the low-pressure compressor speed, when the thermal efficiency of the gas turbine drops by 0.25%, the reduced value of the low-pressure compressor speed should be recorded as n 下降 , That is, the low-pressure compressor speed is: n 出厂 -n 下降 When cleaning, it should be carried out through the flow, Then the subsequent unit operation is determined, and the corresponding low-pressure compressor speed corresponding to the corrected high-pressure compressor speed of (a+b) / 2 is: n 出厂 -n 下降 When cleaning, flow cleaning should be carried out.

3. The determination process according to claim 2, wherein: Atmospheric conditions are: atmospheric pressure 101325Pa, atmospheric temperature 27℃.

4. The determination process according to claim 2, wherein: In step 3, the corrected high-pressure compressor speed in the middle region is selected as a reference, specifically: the middle value of the two end point values ​​of the pollution judgment region is taken as the reference.

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