A gas turbine water washing early warning method

Abstract

The present invention discloses a gas turbine water washing early warning method. First, the compressor inlet reference flow m is defined in the performance calculation module of the water washing system. C , compressor base isentropic efficiency η Cbase , Gas turbine ISO operating condition correction load P c , compressor inlet flow m1 and compressor isentropic efficiency η c Then the performance calculation module receives the operating data collected by the measuring points on the gas turbine and calculates P c 、m1、m C ,η C and η Cbase The value of ISO operating condition reference load P of gas turbine is input into the performance calculation module. Cbase Value, if (P Cbase ‑P c ) / P Cbase 、(m C ‑m1) / m C and (η Cbase ‑η C ) / η Cbase If the values of are all greater than the corresponding thresholds preset in the water wash system's performance calculation module, the water wash system triggers a water wash alarm. This method compares the difference ratios between the three technical indicators under the current operating conditions and the baseline values with the preset corresponding thresholds. If the difference ratios of all three are greater than the preset thresholds, the water wash alarm is triggered. This reduces the water wash frequency and improves economic efficiency while maintaining gas turbine performance.

Description

Technical Field

[0001] The present invention relates to the technical field of gas turbines, and in particular to a gas turbine water washing early warning method. Background Art

[0002] During the long-term operation of a gas turbine, particulate pollutants such as dust and oil in the air will enter the compressor and adhere to the compressor blades, causing scaling in the compressor flow section, reducing the compressor's pressure ratio and efficiency, and subsequently causing a decrease in gas turbine output and load. At the same time, the unit's operating line will approach the surge boundary line, increasing the risk of surge, and the compressor blades will also be corroded by salt accumulation, affecting the unit's life. Therefore, to address the above problems, the gas turbine is equipped with an online / offline water washing system. By washing the compressor with water, dust and scaling are removed from the compressor flow section, improving the performance of the gas turbine.

[0003] Currently, there are two main methods for water washing systems to determine whether to perform water washing: 1. Automatic water washing is performed when the gas turbine has accumulated a certain amount of running time; 2. Operators manually initiate water washing when they determine, based on performance changes, that the gas turbine's performance has deteriorated to a level requiring water washing. With the first water washing method, since the water washing interval is relatively fixed, the time interval between two water washings is often short to ensure gas turbine performance, making it less economical. With the second water washing method, since the actual performance of the gas turbine is affected by external conditions such as ambient temperature, pressure, humidity, and natural gas composition, it is inaccurate to rely solely on manual judgment of gas turbine performance changes to determine whether to perform water washing under changing environmental conditions. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a gas turbine water washing early warning method that can improve the economy while ensuring the performance of the gas turbine.

[0005] The present invention adopts the following technical solutions:

[0006] The present invention provides a gas turbine water washing early warning method. First, the compressor inlet reference flow m is defined in the performance calculation module of the water washing system. C , compressor base isentropic efficiency η Cbase , Gas turbine ISO operating condition correction load P c , compressor inlet flow m1 and compressor isentropic efficiency η C Then the performance calculation module receives the operating data collected by the measuring points on the gas turbine and calculates P c 、m1、m C , η2 and η Cbase The value of ISO operating condition reference load P of gas turbine is input into the performance calculation module.Cdbase Value, if (P Cbase -P c ) / P Cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase If the values of are greater than the corresponding thresholds preset in the performance calculation module of the water washing system, the water washing system triggers a water washing alarm.

[0007] Preferably, the following equation is used to define the compressor inlet reference flow rate m C :

[0008]

[0009] , where T cin is the compressor inlet temperature, P cin is the compressor inlet pressure, a i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, P cout is the compressor outlet pressure, and b is the polynomial constant.

[0010] Preferably, the following equation is used to define the compressor base isentropic efficiency η Cbase :

[0011]

[0012] , where c i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure, and d is the polynomial constant.

[0013] Preferably, the gas turbine ISO operating condition correction load P is defined as c The correction formula used is:

[0014]

[0015] Where PEL is the actual load of the gas turbine, K1 is the ambient pressure correction factor, K2 is the ambient temperature and humidity correction factor, K3 is the intake pressure loss correction factor, K4 is the exhaust pressure loss correction factor, K5 is the IGV correction factor, and K6 is the LHV and C / H correction factor of natural gas.

[0016] Preferably, the equation used to define the compressor inlet flow m1 is:

[0017] m1×h1+m2×(LHV+h2)×η B =PEL÷η m +m3×h3

[0018] , where h1 is the compressor inlet enthalpy, m2 is the natural gas flow rate, LHV is the lower heating value of the fuel, h2 is the natural gas enthalpy, η B is the natural gas combustion efficiency, PEL is the actual load of the gas turbine, η m is the mechanical efficiency of the gas turbine, m3 is the turbine exhaust flow rate, h3 is the turbine exhaust enthalpy, and m3 = m1 + m2.

[0019] Preferably, the equations used to obtain the compressor inlet enthalpy h1, the natural gas enthalpy h2, and the turbine exhaust enthalpy h3 are:

[0020]

[0021] , where i is 1, 2, or 3, τ = T / 1000, T is temperature, τ1 = 273.15 / 1000, and a ik is a constant coefficient.

[0022] Preferably, the compressor isentropic efficiency η is defined as C The equation used is:

[0023] η C =(h couts -h1) / (h cout -h1)

[0024] , where h couts is the isentropic enthalpy at the compressor outlet, h1 is the enthalpy at the compressor inlet, and h cout is the compressor outlet enthalpy.

[0025] Preferably, the compressor outlet isentropic enthalpy h is obtained couts The formula used is:

[0026]

[0027] , where h1 is the compressor inlet enthalpy, γ is the adiabatic index of air, R is the air gas constant, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure.

[0028] Preferably, a minimum water washing interval K.OH.01 is set in the water washing system. If (P Cbase -P c ) / P Cbase 、(m C -m1) / m Cand (η Cbase -η C ) / η Cbase The values of are all greater than the corresponding thresholds preset in the performance calculation module of the water washing system. At the same time, the water washing system detects that the time interval from the last water washing is greater than the minimum water washing interval K.OH.01, then the water washing system triggers the water washing alarm.

[0029] Preferably, a maximum water washing interval K.OH.02 is set in the water washing system. When the water washing system detects that the time interval from the last water washing is greater than the maximum water washing interval K.OH.02, the water washing system triggers a water washing alarm.

[0030] Compared with the prior art, the present invention has significant improvements:

[0031] The gas turbine water washing early warning method of the present invention utilizes three technical indicators that are most relevant to the cleanliness of the compressor, and compares the difference ratios between the three technical indicators under the current operating conditions and the benchmark values with the preset corresponding thresholds. If the difference ratios of the three are all greater than the preset corresponding thresholds, it indicates that the operating efficiency of the gas turbine is lower than expected. At this time, the water washing system triggers a water washing alarm to remind the operating personnel to water wash the compressor, thereby reducing the water washing frequency and improving economic efficiency while ensuring the performance of the gas turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a gas turbine water wash early warning method in an embodiment of the present invention.

[0033] Figure 2 This is a logic diagram of a gas turbine water washing early warning method in an embodiment of the present invention when used on a water washing system with an automatic online water washing early warning function. DETAILED DESCRIPTION

[0034] The following is a further detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, and are not intended to limit the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0037] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0038] like Figures 1 to 2 FIG. 1 shows an embodiment of the gas turbine water washing early warning method of the present invention.

[0039] See also Figure 1 and Figure 2 In the gas turbine water washing early warning method of this embodiment, first, the compressor inlet reference flow m is defined in the performance calculation module of the water washing system. C , compressor base isentropic efficiency η Cbase , Gas turbine ISO operating condition correction load P c , compressor inlet flow m1 and compressor isentropic efficiency η C Then the performance calculation module receives the operating data collected by the measuring points on the gas turbine and calculates P c 、m1、m C ,η C and η Cbase The value of ISO operating condition reference load P of gas turbine is input into the performance calculation module. Cbase Value, if (P Cbase -P c ) / P Cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase If the values of are greater than the corresponding thresholds preset in the performance calculation module of the water washing system, the water washing system triggers a water washing alarm.

[0040] The gas turbine water wash early warning method of this embodiment utilizes three technical indicators most relevant to compressor cleanliness. The method compares the difference ratios between the three technical indicators under current operating conditions and baseline values with preset corresponding thresholds. If all three difference ratios are greater than the preset corresponding thresholds, it indicates that the gas turbine's operating efficiency is lower than expected. In this case, the water wash system triggers a water wash alarm, reminding operators to perform water wash on the compressor. This reduces the frequency of water washes and improves economic efficiency while ensuring gas turbine performance. Furthermore, the gas turbine water wash early warning method of this embodiment triggers an alarm only when the difference ratios between the three technical indicators of gas turbine load, compressor inlet flow rate, and compressor isentropic efficiency and baseline values are all greater than the preset corresponding thresholds. This helps eliminate interference caused by intake pressure loss and more accurately determines whether the compressor requires water wash. Furthermore, the gas turbine water wash early warning method of this embodiment uses existing measurement points on the gas turbine to collect operating data, eliminating the need to modify unit components or add new measurement points. On-site implementation is time-consuming, cost-effective, and safe and reliable.

[0041] It should be noted that, in this embodiment, the ISO operating reference load P of the gas turbine is Cbbase The initial value of is pre-calculated by the gas turbine performance calculation software; at the same time, considering the influence of unit aging, after each water washing of the gas turbine, a full load point (for example, the first full load point of stable operation for 5 minutes after 1 hour of water washing) is taken as the load value of the new gas turbine ISO operating condition reference load P after ISO operating condition correction. Cbase , and update the value in the performance calculation module, and correct P Cbase The methods used and the modified P c The method used is the same.

[0042] Since the reference values of the three technical indicators in the gas turbine water washing early warning method of this embodiment are also dynamically changed through calculation, it can cover part of the load, realize monitoring within the entire operating range, and accurately judge whether the compressor needs water washing.

[0043] In addition, (P Cbase -P c ) / P Cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase When compared with the preset corresponding thresholds, only two of the quantities may be selected to influence the triggering of the water washing alarm of the water washing system, or the three quantities may be jointly influenced with different weights to influence the triggering of the water washing alarm of the water washing system.

[0044] Preferably, see Figure 1 and Figure 2In this embodiment, the performance calculation module of the water washing system is divided into three parts, namely the gas turbine power module, the compressor flow module and the compressor efficiency module. The gas turbine power module is preset with the gas turbine ISO operating load threshold and defines the gas turbine ISO operating reference load P Cbase and gas turbine ISO operating condition corrected load P c The compressor flow module has a preset compressor inlet flow threshold, and defines the compressor inlet reference flow m C and the compressor inlet flow rate m1, the compressor efficiency module is preset with a compressor isentropic efficiency threshold, and the compressor benchmark isentropic efficiency η is defined Cbase and compressor isentropic efficiency η C .

[0045] Preferably, the following equation is used to define the compressor inlet reference flow rate m C :

[0046]

[0047] , where T cin is the compressor inlet temperature, P cin is the compressor inlet pressure, a i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, P cout is the compressor outlet pressure, and b is the polynomial constant.

[0048] It should be noted that the compressor inlet temperature T can be obtained by running the measuring point on the gas turbine. cin , compressor inlet pressure P cin , compressor inlet guide vane opening IGV, gas turbine speed n, compressor outlet pressure P cout , and the polynomial coefficient a i and the polynomial constant term b are known quantities that can be obtained through the gas turbine unit model, and the values corresponding to different gas turbine units are also different.

[0049] Preferably, the following equation is used to define the compressor base isentropic efficiency η Cbase :

[0050]

[0051] , where c i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure, and d is the polynomial constant.

[0052] It should be noted that the compressor inlet guide vane opening IGV, gas turbine speed n, and compressor inlet temperature T can be obtained by running the measuring points on the gas turbine. cin , compressor outlet pressure P cout , compressor inlet pressure P cin , and the polynomial coefficient c i and the polynomial constant term d are known quantities that can be obtained through the gas turbine unit model, and the values corresponding to different gas turbine units are also different.

[0053] Preferably, the gas turbine ISO operating condition correction load P is defined as c The correction formula used is:

[0054]

[0055] Where PEL is the actual load of the gas turbine, K1 is the ambient pressure correction factor, K2 is the ambient temperature and humidity correction factor, K3 is the intake pressure loss correction factor, K4 is the exhaust pressure loss correction factor, K5 is the IGV correction factor, and K6 is the LHV and C / H correction factor of natural gas.

[0056] It should be noted that the actual load PEL, ambient temperature TV1, ambient pressure PV1, ambient relative humidity RH, inlet pressure loss DPI, exhaust pressure loss DPO, fuel carbon-hydrogen ratio C / H and fuel composition, and compressor inlet guide vane opening IGV of the gas turbine can be obtained by operating the measuring points on the gas turbine; by substituting the obtained fuel composition into the equation LHV=f(fuel composition) compiled in accordance with GB / T11062-1998 "Calculation method of calorific value, density, relative density and Wobbe index of natural gas", the fuel lower heating value LHV is solved; by substituting the above-mentioned detected operating data and the solved fuel lower heating value LHV into the preset correction relationship in the performance calculation module, the gas turbine ISO operating condition corrected load P can be calculated. c The six correction coefficients in the correction formula used, and the preset correction relationship can be adaptively adjusted according to the actual working conditions.

[0057] Preferably, the equation used to define the compressor inlet flow m1 is:

[0058] m1×h1+m2×(LHV+h2)×η B =PEL÷η m +m3×h3

[0059] , where h1 is the compressor inlet enthalpy, m2 is the natural gas flow rate, LHV is the lower heating value of the fuel, h2 is the natural gas enthalpy, η B is the natural gas combustion efficiency, PEL is the actual load of the gas turbine, ηm is the mechanical efficiency of the gas turbine, m3 is the turbine exhaust flow rate, h3 is the turbine exhaust enthalpy, and m3 = m1 + m2.

[0060] It should be noted that the natural gas flow rate m2, fuel composition, and actual gas turbine load PEL can be obtained by operating the measuring points on the gas turbine. By substituting the obtained fuel composition into the equation LHV = f(fuel composition) compiled in accordance with GB / T11062-1998 "Calculation Method of Calorific Value, Density, Relative Density and Wobbe Index of Natural Gas", the fuel lower heating value LHV can be solved.

[0061] At the same time, the current relative load value rel load of the unit can be obtained by running the measuring point on the gas turbine, and the relative load value rel load and the natural gas combustion efficiency η can be substituted respectively. B , relative load value rel load and gas turbine mechanical efficiency η m The natural gas combustion efficiency η can be solved by using the characteristic table B and the gas turbine mechanical efficiency η m .

[0062] Preferably, the equations used to obtain the compressor inlet enthalpy h1, the natural gas enthalpy h2, and the turbine exhaust enthalpy h3 are:

[0063]

[0064] , where i is 1, 2, or 3, τ = T / 1000, T is temperature, τ1 = 273.15 / 1000, and a ik is a fixed coefficient.

[0065] It should be noted that the compressor inlet temperature T can be obtained by running the measuring point on the gas turbine. cin , fuel temperature T fuel and turbine exhaust temperature TV4, substitute the above three temperature values into h i From the equation, we can solve for the compressor inlet enthalpy h1, natural gas enthalpy h2 and turbine exhaust enthalpy h3.

[0066] Preferably, the compressor isentropic efficiency η is defined as C The equation used is:

[0067] η C =(h couts -h1) / (h cout -h1)

[0068] , where h couts is the isentropic enthalpy at the compressor outlet, h1 is the enthalpy at the compressor inlet, and h cout is the compressor outlet enthalpy.

[0069] It should be noted that the compressor inlet temperature T can be obtained by running the measuring point on the gas turbine. cin and compressor outlet temperature T cout , and respectively T cin and T cout Substitute h i The equation can be solved to obtain the compressor inlet enthalpy h1 and the compressor outlet enthalpy h cout .

[0070] Preferably, the compressor outlet isentropic enthalpy h is obtained couts The formula used is:

[0071]

[0072] , where h1 is the compressor inlet enthalpy, γ is the adiabatic index of air, R is the air gas constant, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure.

[0073] It should be noted that γ can generally be taken as 1.4, and the compressor inlet temperature T can be obtained by running the measuring point on the gas turbine. cin , compressor outlet pressure P cout , compressor inlet pressure P cin , T cin Substitute h i The compressor inlet enthalpy h1 can be solved by the equation.

[0074] Preferably, see Figure 2 , set the minimum water washing interval K.OH.01 in the water washing system, if (P Cbase -P c ) / P Cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase If the values of are greater than the corresponding thresholds preset in the water wash system's performance calculation module, and the water wash system detects that the time interval since the last water wash is greater than the minimum water wash interval (K.OH.01), the water wash system triggers the water wash alarm. Setting the minimum water wash interval (K.OH.01) prevents the gas turbine from frequently triggering the water wash alarm due to certain uncertainties, thereby improving economic efficiency.

[0075] Preferably, see Figure 2The water wash system sets a maximum water wash interval (K.OH.02). When the system detects that the time interval since the last water wash is greater than the maximum water wash interval (K.OH.02), the water wash system triggers the water wash alarm. Setting the maximum water wash interval (K.OH.02) prevents the gas turbine from failing to trigger the water wash alarm for extended periods due to uncertainties, which could affect the gas turbine's operating efficiency.

[0076] See also Figure 2 Since activating the automatic online water washing warning function of the water washing system when the opening of the compressor inlet guide vane opening IGV is zero will cause an error in the correction result, therefore, when the gas turbine water washing warning method of this embodiment is used for a water washing system with an automatic online water washing warning function, the automatic online water washing warning function of the water washing system can only be activated when the compressor inlet guide vane opening IGV is opened.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A gas turbine water washing early warning method, characterized in that: First, define the compressor inlet reference flow m in the performance calculation module of the water washing system C , compressor base isentropic efficiency η Cbase , Gas turbine ISO operating condition correction load P c , compressor inlet flow m1 and compressor isentropic efficiency η C Then the performance calculation module receives the operating data collected by the measuring points on the gas turbine and calculates P c 、m1、m C ,η C and η Cbase The value of the ISO operating condition reference load P of the gas turbine is input into the performance calculation module. Cbase Value, if (P Cbase -P c ) / P Cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase If the values of are all greater than the corresponding thresholds preset in the performance calculation module of the water washing system, the water washing system triggers a water washing alarm; The following equation is used to define the compressor inlet reference flow rate m C : Where, T cin is the compressor inlet temperature, P cin is the compressor inlet pressure, a i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, P cout is the compressor outlet pressure, and b is the polynomial constant.

2. The gas turbine water washing early warning method according to claim 1, characterized in that: The compressor base isentropic efficiency η is defined by the following equation: Cbase : Where c i is the polynomial coefficient, IGV is the compressor inlet guide vane opening, n is the gas turbine speed, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure, and d is the polynomial constant.

3. The gas turbine water washing early warning method according to claim 1, characterized in that: Define the gas turbine ISO operating condition correction load P c The correction formula used is: Where PEL is the actual load of the gas turbine, K1 is the ambient pressure correction factor, K2 is the ambient temperature and humidity correction factor, K3 is the intake pressure loss correction factor, K4 is the exhaust pressure loss correction factor, K5 is the IGV correction factor, and K6 is the correction factor for the LHV and C / H ratio of natural gas.

4. The gas turbine water washing early warning method according to claim 1, characterized in that: The equation used to define the compressor inlet flow rate m1 is: m1×h1+m2×(LHV+h2)×η B =PEL÷η m +m3×h3 Where h1 is the compressor inlet enthalpy, m2 is the natural gas flow rate, LHV is the lower heating value of the fuel, h2 is the natural gas enthalpy, and η B is the natural gas combustion efficiency, PEL is the actual load of the gas turbine, η m is the mechanical efficiency of the gas turbine, m3 is the turbine exhaust flow rate, h3 is the turbine exhaust enthalpy, and m3 = m1 + m2.

5. The gas turbine water washing early warning method according to claim 4, characterized in that: The equations used to obtain the compressor inlet enthalpy h1, natural gas enthalpy h2, and turbine exhaust enthalpy h3 are: Where, the value of i is 1, 2, 3, τ = T / 1000, T is temperature, τ1 = 273.15 / 1000, a ik is a constant coefficient.

6. The gas turbine water washing early warning method according to claim 1, characterized in that: Define the compressor isentropic efficiency η C The equation used is: or C =(h couts -h1) / (h cout -h1) Where h couts is the isentropic enthalpy at the compressor outlet, h1 is the enthalpy at the compressor inlet, and h cout is the compressor outlet enthalpy.

7. The gas turbine water washing early warning method according to claim 6, characterized in that: Obtain the isentropic enthalpy h at the compressor outlet couts The formula used is: Where h1 is the compressor inlet enthalpy, γ is the adiabatic index of air, R is the air gas constant, T cin is the compressor inlet temperature, P cout is the compressor outlet pressure, P cin is the compressor inlet pressure.

8. The gas turbine water washing early warning method according to claim 1, characterized in that: In the water washing system, a minimum water washing interval K.OH.01 is set. If (P Cbase -P c ) / P cbase 、(m C -m1) / m C and (η Cbase -η C ) / η Cbase The values of are all greater than the corresponding thresholds preset in the performance calculation module of the water washing system, and at the same time the water washing system detects that the time interval from the last water washing is greater than the minimum water washing interval K.OH.01, then the water washing system triggers the water washing alarm.

9. The gas turbine water washing early warning method according to claim 1, characterized in that: A maximum water washing interval K.OH.02 is set in the water washing system. When the water washing system detects that the time interval from the last water washing is greater than the maximum water washing interval K.OH.02, the water washing system triggers a water washing alarm.

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