Gas turbine starting rule research method

Abstract

The invention relates to a gas turbine starting rule research method. The method comprises the following steps: S1, determining gas turbine starting requirements according to a gas turbine overall structure and a unit installation structure; s2, gas compressor characteristic calculation, turbine characteristic calculation, combustion chamber starting calculation and overall performance calculation of the gas turbine are carried out; respectively obtaining a gas compressor characteristic map, a turbine characteristic map, flow distribution of each gas inlet position, maximum exhaust temperature limit and maximum working limit; s3, determining the requirement of a starting motor; s4, calculating a transient working curve and a starting characteristic curve of the gas compressor in the starting process according to the characteristic calculation results of the gas compressor and the turbine; s5, according to the transient working curve and the starting characteristic curve, the equivalent relation between the rotating speed of the gas turbine and the natural gas inlet amount is calculated; and S6, carrying out test run verification and correcting the equivalent relationship in S5. The starting rule can enable the gas turbine to be started smoothly, and a basis is provided for natural gas control of the gas turbine.

Description

Technical Field

[0001] The invention relates to a gas turbine design technology, in particular to a method for studying the starting law of a gas turbine. Background Art

[0002] Distributed energy is an energy system that generates electricity through gas turbines and can provide combined cooling, heating and power. Gas turbines burn natural gas to provide power for the system, which is highly economical and environmentally friendly and is increasingly widely used. Among them, 1.5MW gas turbines (such as DR15 gas turbines) have a high application prospect. When the gas turbine is started, the compressor is driven to rotate by an external power device until the gas turbine turbine can independently provide sufficient mechanical work to maintain the operation of the unit. During the start-up process of the gas turbine, an external starter (such as an electric motor) is required to drive the compressor in the initial stage. When the external starter drives the compressor to a certain speed, air is sucked in and compressed, and then enters the combustion chamber to mix with fuel for combustion. The high-temperature and high-pressure gas generated in this process flows into the turbine, driving the turbine to rotate and do work, thereby driving the compressor to continue working. Once the mechanical work generated by the turbine exceeds the mechanical work required by the compressor, the external starter can be disconnected, that is, disconnected from the gas turbine, and the gas turbine can rely on its own power to maintain operation. This process marks the transformation of the gas turbine from relying on external power to achieving self-sustaining operation. In addition, the start-up process of the gas turbine involves multiple key steps and parameter controls, such as pre-start inspection and preparation, cold operation, purge, ignition, speed increase, etc. These steps ensure that the gas turbine can safely and reliably reach high-speed operation from a stationary state.

[0003] During startup, the amount of natural gas entering the gas turbine is proportional to the speed. The higher the speed and the greater the power, the greater the amount of natural gas required. When the amount of natural gas entering is low, the speed will not meet the requirements and a sudden stop will occur; when the amount of natural gas entering is too high, exhaust gas will be overheated. Therefore, it is necessary to master the starting law of the gas turbine according to the influencing factors and parameters during the startup of the gas turbine, determine the corresponding relationship between the amount of natural gas entering and the speed, and control the amount of natural gas entering according to the corresponding relationship so that the gas turbine can start normally. At present, there is no research method for the starting law that can be used as a reference.

[0004] The invention patent with publication number CN118088324A discloses a method for controlling the fuel flow of a gas turbine, and discloses a curve between the compressor outlet pressure CDP and the fuel upper limit ACU. It is a summary of the rules of gas turbine operation, but it is not the relationship between the speed and the gas turbine flow at startup, and there is no disclosure of a research method for this relationship. Summary of the invention

[0005] The invention provides a method for studying the starting law of a gas turbine, which is used to solve the technical problems existing in the prior art.

[0006] A method for studying the starting law of a gas turbine, wherein the starting law is the corresponding relationship between the speed and the amount of gas entering the gas turbine when the gas turbine is started, so that the gas turbine can be ignited stably and started smoothly, and the method comprises the following steps:

[0007] S1. Determine the starting requirements of the gas turbine according to the overall structure of the gas turbine and the installation structure of the unit; the starting requirements include fuel system requirements and starting restrictions;

[0008] S2. Calculate the compressor characteristics, turbine characteristics, combustion chamber start-up and overall performance of the gas turbine; the compressor characteristics calculation is used to obtain a compressor characteristics map, the turbine characteristics calculation is used to obtain a turbine characteristics map, the combustion chamber start-up calculation is used to obtain the flow distribution of each intake position, and the overall performance calculation is used to obtain the maximum exhaust temperature limit and the maximum working limit;

[0009] S3, determine the starting motor requirements;

[0010] S4. Calculate the compressor transient working curve and starting characteristic curve during the starting process according to the calculation results of the compressor and turbine characteristics;

[0011] S5, calculating the equivalent relationship between the gas turbine speed and the amount of natural gas entering according to the transient working curve and the starting characteristic curve;

[0012] S6. Test run to verify and correct the equivalent relationship described in S5.

[0013] Furthermore, the fuel system requirements in step S1 include natural gas dosage range requirements, metering accuracy requirements, full-stroke action time of the regulating valve, fuel cut-off time when power is off or a stop signal is received, and natural gas intake pressure.

[0014] Furthermore, the starting restrictions in step S1 include the time limit for starting acceleration to 5000r / min, the time from successful ignition to 4000r / min, the time for accelerating from 14000r / min to 25900r / min, the overspeed, and the overtemperature.

[0015] Furthermore, the calculation domain of the compressor characteristic calculation includes a centrifugal impeller, a radial diffuser, and an axial diffuser. The characteristic maps of the compressor rated speed at 20%, 40%, and 40% are first calculated, and then the full speed characteristic map is calculated.

[0016] Furthermore, in the step S2, the turbine characteristics are calculated using three-dimensional CFX characteristics, and steady calculations are performed on different expansion ratios at 70%, 80%, 90%, 100%, and 110% of the rated speed for all design points to form a characteristic map.

[0017] Furthermore, in the step S2, the combustion chamber calculation is to perform aerodynamic performance calculation on the flame tube to obtain the flow distribution of each intake position, and perform velocity field analysis and pressure field analysis on each position of the combustion chamber to obtain the ignition position.

[0018] Furthermore, in the step S4, the conditions for calculating the compressor transient working curve and the starting characteristic curve are: the gas turbine rotational inertia constant, nozzle diameter, nozzle area, starting motor power, and rated speed.

[0019] Furthermore, in step S5, based on the compressor transient operating curve and starting characteristic curve obtained in step S4, the air flow rate under each speed condition is calculated, the combustion amount of natural gas under the air flow rate is calculated, and the natural gas intake amount corresponding to each speed is determined.

[0020] Furthermore, the ignition position should be determined at a position where the airflow is concentrated and the flow velocity is slow.

[0021] Furthermore, the proportion of the natural gas after the air and the natural gas are mixed is no higher than 2.5%.

[0022] Furthermore, the ignition nozzle extends out of the flow stabilizer plate by 3 mm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention obtains the performance parameters such as air flow and air pressure ratio corresponding to the rated speed of the design point, as well as the ignition position, temperature limit, working limit and other indicators by calculating the characteristics of the compressor and gas turbine, as well as the aerodynamic calculation of the combustion chamber and the overall performance calculation of the gas turbine. According to the natural gas combustion amount that can be satisfied by the air flow and the allowable natural gas mixing ratio, the influence of the comprehensive turbine workmanship on the compressor and other factors, the natural gas supply corresponding to each speed is calculated, and the proportional relationship between the speed and the natural gas supply when the gas turbine is started is formed. The parameters and the ignition position are verified and modified through the test run, and the starting law is formed. This law provides a basis for starting the gas turbine with natural gas and establishing a natural gas supply control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Compare the calculated flow paths of gas turbines with those in engineering drawings;

[0026] Figure 2 It is the computational domain model of the compressor;

[0027] Figure 3 Compressor low speed characteristic diagram;

[0028] Figure 4 Schematic diagram of the combustion chamber calculation domain;

[0029] Figure 5 Compressor component characteristic diagram;

[0030] Figure 6 Turbine component characteristic diagram;

[0031] Figure 7 The transient operating line of the compressor when starting with natural gas fuel;

[0032] Figure 8 Natural gas fuel engine starting characteristics - speed / time variation relationship diagram;

[0033] Fig. 9 Natural gas fuel engine starting characteristics - fuel consumption characteristics diagram;

[0034] Fig.10 Natural gas fueled engine starting characteristics - turbine exhaust temperature diagram;

[0035] Fig.11 Starting characteristics of natural gas fueled combustion engines - the relationship between fuel flow rate and turbine exhaust temperature and speed;

[0036] Fig.12 Cold transfer curve diagram. DETAILED DESCRIPTION

[0037] In order to clearly illustrate the technical features of the application scheme of the present invention, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0039] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0040] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, reference terms; "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like are intended to mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0042] Example 1

[0043] This embodiment takes a 1.5MW single-rotor gas turbine as an example to specifically illustrate a method for studying the starting law of a gas turbine, which is used to study the relationship between the starting speed of the gas turbine and the natural gas supply. The specific method is as follows:

[0044] S1. Determine the starting requirements of the gas turbine according to the overall structure of the gas turbine and the installation structure of the unit; the starting requirements include fuel system requirements and starting restrictions.

[0045] The gas turbine is a single-rotor gas turbine engine, which consists of six major components: reducer, air intake, compressor, combustion chamber, turbine and exhaust section, as well as seven major systems to ensure the normal operation of the gas turbine: control system, fuel system, lubricating oil system, air system, ignition system, starting system and cleaning system. The gas generator rotor rotates counterclockwise (against the exhaust direction).

[0046] The functional requirements of the gas turbine are as follows:

[0047] Rated power is 1500kW, gas generator rotor speed is 27245r / min, and gearbox output speed is 1500r / min. Using natural gas fuel, the gas turbine can realize cold start, start, normal stop, emergency stop and other functions. During the start-up process, important parameters such as natural gas flow, speed, exhaust temperature, etc. can be monitored and limited for protection. The gas turbine has abnormal state protection functions such as over-speed, over-temperature, flameout, vibration, etc.

[0048] During the start-up process of the gas turbine, the requirements for the fuel system are shown in Table 1 Fuel System Requirements.

[0049] Table 1 Fuel system requirements

[0050]

[0051]

[0052] Safety restrictions are imposed on relevant parameters during the gas turbine startup process, and alarm values ​​and shutdown values ​​are determined, as shown in the startup restriction parameter table in Table 2 below.

[0053] Table 2 Starting limit parameters

[0054]

[0055] S2. Calculate the compressor characteristics, turbine characteristics, combustion chamber start-up and overall performance of the gas turbine; the compressor characteristics calculation obtains a compressor characteristics map, the turbine characteristics calculation obtains a turbine characteristics map, the combustion chamber start-up calculation is used to obtain the flow distribution of each intake position, and the overall performance calculation is used to obtain the maximum exhaust temperature limit and the maximum working limit.

[0056] (1) Compressor characteristics calculation

[0057] Computational domain model: The basic flow channel used for calculation was extracted from the gas turbine UG model, and the casing flow channel corresponding to the centrifugal impeller tip and the flow channel at the chamfer of each part were adjusted. The casing flow channel corresponding to the centrifugal impeller tip was obtained by offsetting the centrifugal impeller tip flow channel outward by 0.25mm, and the flow channel at the interface of each part was smoothed. Figure 1 As shown in the figure, the engineering drawing flow channel and the calculated flow channel are compared. Except for the centrifugal impeller casing flow channel, the other positions of the two are basically the same. The calculation model includes the inlet guide vane, centrifugal impeller, and radial diffuser. Each row of blades is calculated using a single channel. The calculation domain is shown in the attached Figure 2 shown.

[0058] Meshing: CFD calculations were completed using numerical simulation software ANSYS CFX17.2, and computational meshes were generated using IGG-AutoGrid5 software. The first layer of mesh thickness is 0.003 mm, which meets the requirements for the use of the k-Epsilon turbulence model. The computational domain includes a centrifugal impeller, a radial diffuser, and an axial diffuser, with a total of three rows of blades. The number of mesh units is distributed as shown in Table 3 below, the computational mesh setting table.

[0059] Table 3 Calculation grid settings

[0060] name Number of blades First layer grid size Number of grid nodes Centrifugal impeller 13 3×10-5m 270,000 Radial Diffuser 19 3×10-5m 84,000 Axial diffuser 76 3×10-5m 78,000

[0061] Calculation settings:

[0062] Turbulence model: The k-Epsilon turbulence model is used for calculation, and the viscous work term is checked.

[0063] Numerical calculation format: Use a calculation format with second-order accuracy.

[0064] Interface treatment between blade rows: Two adjacent blade rows adopt the “Stage (Mixing-Plane)” mixing surface method.

[0065] Boundary conditions: total inlet pressure and total temperature are 101325Pa and 288.15K respectively, with uniform axial air intake; static pressure is given at the outlet section, which varies with different working points.

[0066] Tip clearance setting: A tip clearance of 0.25 mm is set at the tip of the centrifugal impeller.

[0067] Calculation results: Since the gas turbine ignites at 20%-40% of the rated speed, there are problems such as greater ignition difficulty at this low speed and greater gas flow error. In view of the low speed characteristics of the gas turbine when starting, the characteristic maps of 20%, 30% and 40% of the rated speed of the compressor are calculated in the software, as shown in the attached figure. Figure 3 As shown. On the basis of obtaining the low speed characteristics, the full speed characteristic diagram is further calculated and obtained on the software.

[0068] (2) Turbine characteristics calculation

[0069] The turbine characteristics are calculated using three-dimensional CFX characteristics. According to the "Three-dimensional Viscous Aerodynamic CFX Calculation Specification for Aviation Gas Turbine Engine Turbines" (Q / 8SFGF40.1031-2010), steady calculations are performed on different expansion ratios of 70%, 80%, 90%, 100%, and 110% of the rated speed for all design points, and finally a characteristic curve is formed.

[0070] (3) Combustion chamber aerodynamic calculation

[0071] Calculation domain model: This calculation only calculates the aerodynamic performance of the combustion chamber flame tube, and removes the guide structure. All air film holes, nozzle internal structure, and carbon deposition groove structure are retained. Figure 4 shown.

[0072] Other simplified processing, the nozzle structure is retained, but the equivalent throttling area is processed for its internal structure; the welding gap is deleted, and the sharp corners are rounded; there is no deflector cooling hole.

[0073] Meshing strategy: ANSYS Mesh 19.2 is used for meshing. The combustion chamber structure is large in size, so tetrahedron and hexahedron mixed meshing is used to minimize the total number of meshes to reduce calculation time and save computing resources.

[0074] All structures including nozzle structure, carbon blowing groove, vortexer structure, heat shield holes, flame tube film holes, main combustion holes, mixing holes, inserted electric nozzle structure, etc. are all segmented independently, and most of the fluid domain is considered to be structured meshed, and finally the entire fluid domain is divided into 1044 blocks and formed into a Part. The final meshing result is shown below. The total number of meshes is about 17.1 million, and the maximum distortion is 0.95.

[0075] Calculation results and analysis:

[0076] Flow distribution, based on Fluent calculation, the flow distribution of each intake position under each calculation state is statistically calculated, as shown in the flow distribution table in Table 4 below.

[0077] Table 4 Flow distribution

[0078]

[0079]

[0080] Through software simulation, we can know that the velocity field analysis shows that since the main combustion holes and mixing holes are evenly distributed in a circle, the air jets with high-temperature air flow converge and intersect at the high center of the combustion chamber cavity, resulting in a high air velocity in the center area of ​​the combustion chamber outlet. The outlet velocity of the guide is relatively high, reaching 220m / s, and the velocity in other areas is between 100 and 180m / s.

[0081] The analysis of the pressure field shows that except for the main combustion hole, mixing hole jet, and vortex finder outlet, the total pressure distribution in the flame tube is relatively low; the total pressure in the flame tube is significantly lower than the total pressure in the external channel; the pressure loss of the guide vane is mainly at the turning point; according to calculations, the total pressure loss in the combustion chamber is about 2.83%, and the total pressure loss in the guide vane is about 0.21%.

[0082] The temperature field analysis shows that the high-temperature airflow gathers toward the center of the combustion chamber cavity along the jet direction of the main combustion hole and the mixing hole, so the temperature at the center of the combustion chamber is higher; the natural gas fuel is mainly distributed on the center line of the flame tube, and there is a small amount of natural gas fuel distributed until the flame tube outlet, which leads to a higher temperature inside the flame tube and at the center of the outlet; the natural gas is distributed in the atomizing air path, proving that the natural gas fuel has a reflux phenomenon. The temperature at the center of the combustion chamber outlet section is the highest. The average outlet temperature is 1314K, the highest temperature is 2114K, the average outlet temperature of the guide device is 1312K, the highest temperature is 1712K, and it is mainly distributed on the upper annular surface of the outlet annular surface. After calculation, the guide device outlet OTDF = 0.567.

[0083] (4) Overall performance calculation

[0084] The software GasTurb is used to establish a gas turbine performance matching model, and the parameters of each section under different speeds and intake conditions are calculated. The overall performance parameters of natural gas fuel and design point are shown in Table 5 below: Table of natural gas fuel parameters of each section under design point state.

[0085] Table 5 Natural gas fuel parameters for each section at design point

[0086]

[0087] Based on the above calculation results of compressor and turbine characteristics, the full speed characteristics of compressor and turbine (20%--110% of rated speed) are simulated in ANSYS. The calculation results are as shown in the attached figure. Figure 5 The full speed characteristic spectrum of the gas turbine compressor components shown in the figure and the attached Figure 5 The full speed characteristic spectrum of the turbine components is shown.

[0088] S3. Determine the requirements for the starting motor. The starting motor of the gas turbine has the following technical requirements:

[0089] Type: three-phase asynchronous variable frequency motor;

[0090] Rotation direction: clockwise (facing the starter motor mounting base);

[0091] Transmission mode: driven by gear box transmission mechanism;

[0092] Rated power: 45kW

[0093] Number of poles: 2P;

[0094] Power supply voltage: 380VAC;

[0095] Rated frequency: 50Hz;

[0096] Rated speed: 3000r / min (corresponding to gas turbine speed 12048r / min);

[0097] Maximum allowable speed: 3600r / min;

[0098] Maximum torque: 286N·m;

[0099] S4. Calculate the compressor transient working curve and starting characteristic curve during the starting process according to the calculation results of the compressor and turbine characteristics;

[0100] The gas turbine moment of inertia is 3.555 kg·m 2 (including the turbine rotor, gearbox and generator); the nozzle is a circular surface with a diameter of 414mm and a nozzle area of ​​0.1346m2; the starting motor power is 45kW and the rated speed is 3000r / min. Based on the above conditions, the transient working curve of the compressor during the starting process (0~25900r / min) of the turbine is calculated by simulation in ANSYS (see attached). Figure 7 ) and starting characteristic curve (see attached Figure 8-11 ).

[0101] S5, calculating the equivalent relationship between the gas turbine speed and the amount of natural gas entering according to the transient working curve and the starting characteristic curve;

[0102] According to the characteristic curve in S4, the air flow rate at each speed can be obtained, and the amount of natural gas that can be burned under the air flow rate and the influence of natural gas on the power provided by the compressor can be calculated. The natural gas demand corresponding to each speed during the startup process can be obtained, and the intake amount of the gas turbine can be controlled according to the demand. The table below shows the natural gas flow rate corresponding to each speed:

[0103] Table 6 Natural gas flow rate corresponding to each speed

[0104]

[0105]

[0106] S6. Test run to verify and correct the equivalent relationship described in S5.

[0107] Start the gas turbine for test verification. The gas turbine starting procedure is as follows:

[0108] (1) Start the auxiliary lubricating oil pump and check whether the lubricating oil pressure is normal (≥0.022MPa).

[0109] (2) 0s, press the start button, the starter motor is powered on, and the vibration parking detection is turned on.

[0110] (3) Within 25 seconds after starting, the speed increases to 5000r / min.

[0111] (4) Cold run at (5500±55) r / min for 480 s.

[0112] (5) After the 180s countdown for cold run is completed, the high-energy igniter ignites for 5s, and the natural gas regulating valve is opened according to the natural gas flow rate corresponding to 5500r / min.

[0113] (6) The high-energy igniter continues to ignite for 8 seconds, the gas fuel quick shut-off valve opens, the vent valve closes, and fuel gas begins to be supplied to the nozzle.

[0114] (7) After the ignition is successful, judging by the exhaust temperature rise within 8 seconds, the high-energy igniter is powered off and the engine speed is increased.

[0115] (8) Within 60 seconds after ignition, the speed increases to 14,000 r / min and the starter motor is powered off and disengaged.

[0116] (9) From 14,000 r / min, the speed increases to 25,900 r / min (about 95% of the rated speed) within 40 seconds.

[0117] (10) When the speed increases to 20,000 r / min, the auxiliary lubricating oil pump is powered off.

[0118] (11) When the speed reaches 25900 r / min, the engine enters the slow running state and runs stably at 25900 r / min, and the start-up is completed.

[0119] According to the flow parameters in the corresponding relationship between the rotation speed and the natural gas demand obtained in step S5, the natural gas supply at each rotation speed of the gas turbine is controlled, and the gas turbine is started according to the above starting procedure to verify whether the start of the gas turbine is normal and the matching of the natural gas supply and the operation of the gas turbine. The problems found in the verification are corrected to obtain the final corresponding relationship between the rotation speed and the natural gas demand, and the corresponding relationship is the gas turbine starting law disclosed in this embodiment.

[0120] Example 2

[0121] This embodiment provides a method for studying the starting law of a gas turbine, and more particularly relates to a method for verifying the rotation speed and air flow rate when the gas turbine is started, as follows.

[0122] The method for studying the starting law of the gas turbine is the same as the steps in Example 1. In the test verification of step S6, specifically: before the starting test, the cold start function test of the gas turbine is carried out. The speed is increased to 5500r / min within the specified time and it works stably for 40s. During the cold start process, the gas turbine works stably and the relevant parameters are normal. The cold start curve of the gas turbine is shown in the attached figure. Fig.12 shown.

[0123] After the cold start function test was successful, the No. 001 unit was started and ignited and increased speed according to the gas supply rule in Table 6. After the engine was ignited, the exhaust temperature did not rise and the ignition failed. Preliminary analysis showed that the installation position of the ignition nozzle needed to be adjusted, and the ignition nozzle should be extended out of the flow stabilizer plate and placed in a position where the airflow is concentrated and the flow rate is slow. At the same time, the natural gas flow was adjusted for the first time, increasing the natural gas flow corresponding to each speed, and increasing the flow by 20kg / h on the basis of the original flow.

[0124] The start-up test was carried out again according to the adjusted flow rate. The gas turbine could be ignited successfully, and the exhaust temperature rose to 114°C, but the unit had a deflagration sound and the engine stopped urgently. After inspection, it was found that the connecting bolts of the transfer section outside the unit box were detached, and the transfer section was slightly deformed by the impact near the box. Analysis shows that the modified natural gas flow is unreasonable, resulting in the ratio of natural gas and air accumulated in the pipeline reaching an explosive concentration before the ignition is successful. When the engine ignites successfully, the natural gas in the pipeline is ignited to produce a deflagration, causing damage to the unit transfer section. In the subsequent improvement plan, the exhaust pipeline of the unit is modified to reduce the space for natural gas accumulation; the gas supply flow is recalculated according to the natural gas flow at the head of the engine combustion chamber, and the ratio of natural gas and air after mixing shall not exceed 2.5%. After the unit transfer section was rectified, the natural gas flow corresponding to the engine speed (5500~7500)r / min was adjusted for the second time.

[0125] On the basis of the second flow adjustment, the test run verification is continued. The starting conditions at 8000-9500r / min, the motor disengagement at 14000r / min, the overspeed protection performance at 18000r / min, the speed increase at 23800r / min, the operation when the speed reaches a maximum of 26000r / min, and finally the stable operation at 25900r / min slow speed are verified. The flow mismatch at each stage is adjusted, and finally the relationship between the starting speed and the flow demand of the gas turbine in this embodiment is formed, as shown in Table 7 below:

[0126] Table 7 Correspondence between engine speed and natural gas flow rate when starting successfully

[0127]

[0128]

[0129] Through the test run verification method of this embodiment, the gas turbine can achieve normal cold start, start-up and other functions, and the law of the relationship between the rotation speed and the natural gas supply amount is studied for the start-up of this type of gas turbine.

[0130] Example 3

[0131] This embodiment discloses a method for studying the starting law of a gas turbine. The difference from Embodiment 2 is that in this embodiment, the top of the electric nozzle is extended about 3 mm beyond the flow stabilizer plate, the gas turbine is ignited successfully, the exhaust temperature rises, and the ignition is stable at the installation position of the electric nozzle in this embodiment.

[0132] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for studying the starting law of a gas turbine, characterized in that: The steps include: S1. Determine the starting requirements of the gas turbine according to the overall structure of the gas turbine and the installation structure of the unit; the starting requirements include fuel system requirements and starting restrictions; S2. Calculate the compressor characteristics, turbine characteristics, combustion chamber start-up and overall performance of the gas turbine; the compressor characteristics calculation is used to obtain a compressor characteristics map, the turbine characteristics calculation is used to obtain a turbine characteristics map, the combustion chamber start-up calculation is used to obtain the flow distribution of each intake position, and the overall performance calculation is used to obtain the maximum exhaust temperature limit and the maximum working limit; S3, determine the starting motor requirements; S4. Calculate the compressor transient working curve and starting characteristic curve during the starting process according to the calculation results of the compressor and turbine characteristics; S5, calculating the equivalent relationship between the gas turbine speed and the amount of natural gas entering according to the transient working curve and the starting characteristic curve; S6. Test run to verify and correct the equivalent relationship described in S5.

2. A method for studying the starting law of a gas turbine according to claim 1, characterized in that: The fuel system requirements in step S1 include natural gas dosage range requirements, metering accuracy requirements, full-stroke action time of the regulating valve, fuel cut-off time when power is off or a stop signal is received, and natural gas intake pressure.

3. The method for studying the starting law of a gas turbine according to claim 1, characterized in that: The starting restrictions in step S1 include the time limit for starting acceleration to 5000r / min, the time from successful ignition to 4000r / min, the time for accelerating from 14000r / min to 25900r / min, the overspeed speed, and the overtemperature.

4. The method for studying the starting law of a gas turbine according to claim 1, characterized in that: In the step S2, the compressor characteristics are calculated using CFD, and the characteristic spectra of the compressor rated speed at 20%, 40% and 40% are first calculated, and then the full-speed characteristic spectrum is calculated; the turbine characteristics are calculated using three-dimensional CFX characteristics, and steady-state calculations are performed on different expansion ratios of 70%, 80%, 90%, 100%, and 110% of the rated speed of all design points to form a characteristic spectrum.

5. The method for studying the starting law of a gas turbine according to claim 1, characterized in that: In the step S2, the combustion chamber calculation is to calculate the aerodynamic performance of the flame tube, obtain the flow distribution of each intake position, and perform velocity field analysis and pressure field analysis on each position of the combustion chamber to obtain the ignition position.

6. The method for studying the starting law of a gas turbine according to claim 1, characterized in that: In the step S4, the conditions for calculating the compressor transient working curve and the starting characteristic curve are: the gas turbine rotational inertia constant, nozzle diameter, nozzle area, starting motor power, and rated speed.

7. The method for studying the starting law of a gas turbine according to claim 1, characterized in that: In step S5, the air flow rate under each speed condition is calculated according to the transient working curve and the starting characteristic curve of the compressor obtained in step S4, the combustion amount of natural gas under the air flow rate is calculated, and the natural gas intake amount corresponding to each speed is determined.

8. A method for studying the starting law of a gas turbine according to claim 6, characterized in that: The ignition position is arranged at a position where the airflow is concentrated and the flow velocity is slow.

9. A method for studying the starting law of a gas turbine according to claim 8, characterized in that: The ratio of the natural gas amount after the air and the natural gas are mixed is no higher than 2.5%.

10. A method for studying the starting law of a gas turbine according to claim 8, characterized in that: The ignition nozzle extends out of the current stabilizer plate by 3 mm.

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