Gas turbine system characteristic simulation research method

Abstract

The invention discloses a gas turbine system characteristic simulation research method, a gas turbine comprises a gas compressor, a combustion chamber and a turbine, and the method specifically comprises the following steps: respectively establishing mathematical models for the gas compressor, the combustion chamber and the turbine; performing energy efficiency diagnosis and optimization based on the gas turbine simulation model, wherein the energy efficiency diagnosis and optimization comprise influence of degradation of an air inlet system on thermal performance of a gas turbine and washing optimization of a gas compressor based on actual operation data; modularized modeling analysis simulation is carried out on all parts of the gas turbine, multiple performances of the gas turbine are analyzed and optimized, the characteristics of the gas turbine are comprehensively mastered, key technical support is provided for the construction process of an intelligent operation and maintenance platform of the gas turbine, and convenience is provided for design, analysis, control, operation and maintenance of a thermal system of the gas turbine.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbines, and in particular to a method for simulating and studying characteristics of a gas turbine system. Background Art

[0002] Fault diagnosis, performance diagnosis and operation adjustment of gas-fired generator sets must be based on a comprehensive understanding of gas turbine characteristics. For the gas turbine itself, domestic technicians have long found it difficult to obtain detailed characteristics of the gas turbine. With the development of computer technology, thermal system modeling and simulation technology has become increasingly mature and has gradually become an effective means of designing, analyzing, controlling, operating and maintaining gas turbine thermal systems. This application proposes a gas turbine system characteristics simulation research method to solve the above problems. Summary of the invention

[0003] The main purpose of the present invention is to provide a gas turbine system characteristics simulation research method, aiming to solve the existing technical problems.

[0004] To achieve the above object, the present invention provides a method for simulating and studying the characteristics of a gas turbine system. The gas turbine comprises a compressor, a combustion chamber and a turbine. The method specifically comprises the following steps:

[0005] Mathematical models are established for the compressor, combustion chamber and turbine respectively;

[0006] Energy efficiency diagnosis and optimization are performed based on the gas turbine simulation model, including the impact of intake system degradation on the thermal performance of the gas turbine and the optimization of compressor water washing based on actual operating data.

[0007] Furthermore, the compressor, combustion chamber and turbine are all modeled using a modular modeling method for power system simulation modeling.

[0008] Furthermore, the compressor module and the turbine module are both established in the form of characteristic lines.

[0009] Furthermore, the characteristics of the compressor and turbine components are calculated by any one of a primitive blade cascade method, a step-by-step superposition method, and a characteristic diagram correction method.

[0010] Furthermore, when calculating by the characteristic diagram correction method, scaling, interpolation and translation are adopted to correct the reference characteristic line using the operating data of the actual unit components.

[0011] Furthermore, when calculating by the characteristic diagram correction method, the universal characteristic line is used for translation, interpolation and scaling, so as to obtain the characteristic curve of the actual unit.

[0012] Furthermore, the component characteristic line when the IGV is fully opened 100% is first obtained, and then the characteristic line is corrected based on the change of the IGV angle to make it consistent with the actual unit characteristics.

[0013] Furthermore, the compressor modeling is modeled in the form of equivalent cooling air.

[0014] Furthermore, the total pressure recovery coefficient of the combustion chamber is 97%.

[0015] Furthermore, the characteristic line of the compressor module is described by the changing relationship between the four parameters of the reduced speed Nc, the reduced flow rate Gc, the pressure ratio πc, and the efficiency ηc; the characteristic line of the turbine module is described by the changing relationship between the four parameters of the reduced speed nt, the reduced flow rate Gt, the expansion ratio πt, and the efficiency ηt.

[0016] The beneficial effects of the present invention are embodied in:

[0017] The present invention performs modular modeling, analysis and simulation on various components of the gas turbine, analyzes and optimizes multiple performances of the gas turbine, and comprehensively grasps the characteristics of the gas turbine. This provides key technical support in the construction of an intelligent operation and maintenance platform for gas turbines, and facilitates the design, analysis, control, operation and maintenance of the thermal system of the gas turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 It is a schematic diagram of the overall model of the thermal system of the gas turbine of the present invention;

[0020] Figure 3 This is a calculation flow chart of the gas turbine thermal system model of the present invention.

[0021] Figure 4 Schematic diagram of the compressor efficiency characteristic curve of the present invention;

[0022] Figure 5 It is a schematic diagram of the reduced flow characteristic curve of the compressor of the present invention;

[0023] Figure 6 It is a schematic diagram of the efficiency characteristics of the gas turbine of the present invention;

[0024] Figure 7 It is a schematic diagram of the reduced flow characteristics of the gas turbine of the present invention;

[0025] Figure 8 Schematic diagram of compressor efficiency characteristic curve after I GV correction of the present invention;

[0026] Fig. 9It is a schematic diagram of the compressor flow characteristic curve of the compressor part after I GV correction of the present invention;

[0027] Fig.10 It is a schematic diagram of the change of the thermal performance of the gas turbine of the present invention as the filter pressure difference deteriorates;

[0028] Fig.11 This is a schematic diagram of the diagnosis result after the compressor efficiency is downgraded and the noise is reduced according to the present invention;

[0029] Fig.12 This is a schematic diagram of the diagnosis results after the compressor efficiency is downgraded and the noise is reduced according to the present invention. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 The present invention provides a method for simulating and studying the characteristics of a gas turbine system. The gas turbine comprises a compressor, a combustion chamber and a turbine. The method specifically comprises the following steps:

[0032] Mathematical models are established for the compressor, combustion chamber and turbine respectively;

[0033] Energy efficiency diagnosis and optimization are performed based on the gas turbine simulation model, including the impact of intake system degradation on the thermal performance of the gas turbine and the optimization of compressor water washing based on actual operating data.

[0034] Specifically, the gas turbine system is mainly composed of components such as compressors, combustion chambers, and turbines. It is a complex nonlinear system and fluid network, and there is a coupling relationship between its parameters such as pressure and flow. Therefore, a modular modeling method can be used to achieve simulation modeling of this complex power system. To achieve modular modeling, it is first necessary to establish mathematical models for key gas turbine components such as compressors, combustion chambers, and gas turbines, and implement them through simulation codes. The complex coupling relationship and calculation process between modules can be found in Figure 2 and Figure 3 .

[0035] Specifically, the compressor module. After the air in the environment enters the compressor, it is compressed into a high-temperature, high-pressure working gas by the high-speed rotating blades. A compressor generally operates according to its characteristic line under different working conditions, and the characteristic line of the compressor mainly describes the changing relationship between its four parameters: the reduced speed Nc, the reduced flow Gc, the compression ratio πc, and the efficiency ηc. As long as any two of the parameters are known, the values ​​of the remaining two parameters can be known. Therefore, in the modeling of the compressor module, the relationship between the above four parameters is used to describe the characteristics of the compressor. For typical compressor characteristic curves, please refer to Figure 4 and Figure 5 .

[0036] In the F-class gas engine, a large proportion of air is extracted from different stages of the compressor to cool the turbine blades. However, due to the lack of actual measurement data on the cooling air of the compressor part, this paper uses equivalent cooling air to model it.

[0037] Specifically, the combustion chamber module does not consider the influence of volume inertia in steady state, and satisfies the mass conservation equation. The conservation here is not only the overall mass conservation between air, fuel, and gas, but also the mass conservation of each component before and after these three working fluids. In addition, the combustion chamber module satisfies the energy conservation equation, and the combustion efficiency of the combustion chamber is also considered in this equation. In this project, the combustion efficiency of the combustion chamber is set to 99%. At the same time, considering that there will be some resistance to fuel combustion and gas flow in the combustion chamber, there will be a certain pressure loss at the inlet and outlet of the combustion chamber, and the pressure loss is also crucial for the calculation of the combustion chamber. In this project, the total pressure recovery coefficient of the combustion chamber is taken as 97%.

[0038] Specifically, in the turbine module, the high-temperature and high-pressure gas at the outlet of the combustion chamber expands and does work in the turbine, converting heat energy into mechanical energy. Part of the work output by the gas turbine turbine is used to drive the compressor, and part is used to drive the external load to rotate. The turbine is similar to the compressor, and it also operates according to the characteristic line under different working conditions. The characteristics of the turbine are also described by the changing relationship between the four parameters of the reduced speed nt, the reduced flow rate Gt, the expansion ratio πt, and the efficiency ηt. You only need to know any two of the parameters to know the values ​​of the remaining two parameters. Therefore, the modeling method of the turbine is similar to that of the compressor. For typical curves of gas turbines, please refer to Figure 6 and Figure 7 .

[0039] Correction of component characteristics. Accurate component characteristics are the prerequisite for ensuring diagnostic accuracy. Since the compressor module and the turbine module are established in the form of characteristic lines, and the characteristic lines are difficult to obtain directly from the manufacturer, the component characteristics are generally calculated by the following methods: primitive blade grid method, step-by-step superposition method, and characteristic diagram correction method. Taking the compressor as an example, the primitive blade grid method calculates the characteristics step by step through the geometric shape of each stage of the blade grid, and the step-by-step superposition method calculates the overall performance of the compressor step by step through the stage general characteristic curve. The characteristic diagram correction rule takes into account that when the blade shape and various performance index parameters of the compressor are similar, its characteristic line also has similar trends and curve shapes.

[0040] Through the analysis of the above three methods, this project will adopt the characteristic diagram correction method. Taking the compressor as an example, based on the characteristic curve of the reference compressor, the reference characteristic line is corrected by scaling, interpolating, and translating using the operating data of the actual unit compressor, so that it can match the characteristics of the actual operating compressor. Taking the compressor as an example, this article uses the general characteristic line for translation, interpolation, and scaling to obtain the characteristic curve of its actual unit. In order to operate better, the heavy-duty gas turbine's compressor inlet guide vane (IGV) will continuously change its angle under the control of the control system, and the change of the IGV angle will affect the characteristics of the compressor. Therefore, this article will first obtain the compressor characteristic line when the IGV is fully opened 100%, and then correct the characteristic line based on the change of the IGV angle to make it consistent with the actual unit characteristics. Please refer to the IGV corrected compressor characteristic curve Figure 8 and Fig. 9 .

[0041] Research on energy efficiency diagnosis and optimization based on gas turbine simulation model

[0042] First, the study on the influence of inlet system degradation on the thermal performance of gas turbine

[0043] This part studies the influence of the changes in the inlet system filter pressure difference on the thermal performance of the gas turbine. The influence of three parameters, relative humidity, atmospheric pollutant concentration, and filter degradation state, are mainly considered. Fig.10The influence of three performance parameters, namely gas turbine output power, compressor outlet pressure, and turbine outlet temperature, on changes in three types of pressure difference influencing factors are shown. Among them, relative humidity and atmospheric pollutant concentration are combined into four fixed environmental types, and the filter degradation state is selected as a continuous variable. The performance parameters of the gas turbine technology research report "Research and Application of Intelligent Operation and Maintenance Cloud Platform for Gas Turbines Based on Full-Stack Autonomous and Controllable Technology" are selected as the benchmark performance parameters under the filter pressure difference corresponding to low humidity clean air conditions (RH<60%, DC=0). During the degradation of the filter pressure difference, the fuel flow rate and the IGV opening are controlled to remain unchanged. The calculated changes in the thermal performance of the gas turbine with the degradation of the filter pressure difference are shown in the figure below. Fig.10 As shown in the figure, it can be seen that when the filter is close to the end of its service life, the gas turbine performance is more susceptible to adverse environmental factors. The change of gas turbine thermal performance with the degradation of filter pressure difference can be seen in Fig.10 .

[0044] Second, the optimization study of compressor water washing based on actual operation data

[0045] By inputting the operating data of the gas turbine unit in a certain period of time into the degradation diagnosis model, the changes in compressor performance degradation are calculated based on the operating data. Due to the continuous changes in operating conditions and the existence of measurement errors, the diagnostic results of compressor efficiency degradation and flow degradation fluctuate greatly. It is difficult to use the original data for subsequent neural network model training and trend prediction. Therefore, the above two flow and efficiency diagnostic results are denoised, and the denoising method used is the Gaussian weighted moving average method. Please refer to the two degradation parameters after denoising and the changes in the original degradation. Fig. 9 and Fig.10 .

[0046] from Fig.11 and Fig.12 It can be seen that the 4000h operation can be divided into two stages. In the first stage, the compressor efficiency degradation and flow degradation change slowly. As the operation time increases, the degradation begins to increase rapidly. At about 2300 hours, the compressor efficiency degradation reaches about 2%, and the compressor flow degradation reaches about 5%. After that, the offline water washing is carried out and the second stage of operation begins. It can be seen that as the operation time increases, the fouling degree on the compressor blade surface becomes more and more serious, which will have a greater impact on the performance of the compressor and the performance of the entire gas turbine unit. Therefore, it is necessary to arrange water washing.

[0047] Through the above analysis, the present invention performs modular modeling, analysis and simulation on various components of the gas turbine, analyzes and optimizes multiple performances of the gas turbine, and comprehensively grasps the characteristics of the gas turbine. This provides key technical support in the construction of the gas turbine intelligent operation and maintenance platform, and facilitates the design, analysis, control, operation and maintenance of the gas turbine thermal system.

[0048] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, back, etc., then the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture as shown in the accompanying drawings. If the specific posture changes, the directional indication will also change accordingly.

[0049] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, "multiple" refers to more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for simulating the characteristics of a gas turbine system, wherein the gas turbine comprises a compressor, a combustion chamber and a turbine, and is characterized in that: The method specifically comprises the following steps: Mathematical models are established for the compressor, combustion chamber and turbine respectively; Energy efficiency diagnosis and optimization are performed based on the gas turbine simulation model, including the impact of intake system degradation on the thermal performance of the gas turbine and the optimization of compressor water washing based on actual operating data.

2. The gas turbine system characteristic simulation research method according to claim 1, characterized in that: The compressor, combustion chamber and turbine are all modeled using a modular modeling method for power system simulation modeling.

3. The gas turbine system characteristic simulation research method according to claim 2, characterized in that: The compressor module and the turbine module are both established in the form of characteristic lines.

4. The method for simulating and studying the characteristics of a gas turbine system according to claim 2, wherein: The characteristics of the compressor and turbine components are calculated by any one of the elementary blade cascade method, the step-by-step superposition method and the characteristic diagram correction method.

5. The method for simulating and studying the characteristics of a gas turbine system according to claim 4, characterized in that: When calculating by the characteristic diagram correction method, the reference characteristic line is corrected by using the operation data of the actual unit components in the manner of scaling, interpolation and translation.

6. The method for simulating and studying the characteristics of a gas turbine system according to claim 4, characterized in that: When calculating by the characteristic diagram correction method, the universal characteristic line is used for translation, interpolation and scaling, so as to obtain the characteristic curve of the actual unit.

7. The method for simulating and studying the characteristics of a gas turbine system according to claim 4, characterized in that: The component characteristic line when the IGV is fully opened 100% will be obtained first, and then the characteristic line will be corrected based on the change of the IGV angle to make it consistent with the actual unit characteristics.

8. The method for simulating and studying the characteristics of a gas turbine system according to claim 1, wherein: The compressor modeling adopts the form of equivalent cooling air to model it.

9. The method for simulating and studying the characteristics of a gas turbine system according to claim 1, wherein: The total pressure recovery coefficient of the combustion chamber is taken as 97%.

10. The method for simulating and studying the characteristics of a gas turbine system according to claim 3, wherein: The characteristic line of the compressor module is described by the changing relationship between the four parameters of the reduced speed Nc, the reduced flow rate Gc, the pressure ratio πc, and the efficiency ηc; the characteristic line of the turbine module is described by the changing relationship between the four parameters of the reduced speed nt, the reduced flow rate Gt, the expansion ratio πt, and the efficiency ηt.

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