Axial staged combustion chamber and fuel staging control method and system

Abstract

This invention proposes an axially staged combustor and a fuel staged control method and system, relating to the field of gas turbine combustion technology. The axially staged combustor has multiple premixed nozzles arranged circumferentially at its head, forming first and second premixed stages arranged at intervals, and is equipped with standby diffuser nozzles divided into first and second shift classes. Downstream axially, at least two independent sub-stages of secondary nozzles are arranged. The control method includes: simultaneously igniting all premixed stages and standby fuels for ignition and flame propagation; after successful ignition, simultaneously closing the second premixed stage and second standby fuels, and reopening them when the load reaches a first threshold; opening the first sub-stage of the secondary nozzles when the load reaches a second threshold; gradually closing all standby fuels when the load reaches a third threshold to achieve fully premixed combustion; and opening the second sub-stage of the secondary nozzles when the load reaches a fourth threshold. This invention achieves rapid and uniform flame propagation, low-load low emissions, uniform temperature field under all operating conditions, and suppression of thermoacoustic oscillations through precise staged control and opposite-directional design.

Description

Technical Field

[0001] This invention relates to the field of gas turbine combustor technology, and in particular to an axial staged combustor and a fuel staged control method and system. Background Technology

[0002] To meet increasingly stringent environmental regulations, modern gas turbines widely employ Dry Low Emissions (DLE) combustion technology. Axial staged combustion is an advanced DLE technology widely used in heavy-duty gas turbines and aero engines. Specifically, two or more sets of nozzles are arranged sequentially along the axial direction of the combustion chamber. Typically, the first-stage (or premixed stage) nozzle is located at the head of the combustion chamber, and the second-stage nozzle is located downstream. At low loads, only the first-stage nozzle at the head operates; as the load increases, the second-stage fuel is gradually introduced downstream, thereby achieving control over combustion temperature and equivalence ratio across the entire operating range and effectively suppressing the formation of thermal nitrogen oxides (NOx).

[0003] However, this type of axially staged combustor still faces severe challenges during ignition and low-load stages, with its performance bottleneck mainly concentrated in the head combustion organization. Existing head ignition and low-load stable combustion strategies have the following main drawbacks: First, when using a multi-nozzle tortuous flame propagation scheme, it relies on a central nozzle to complete the flame connection, which is structurally limited and has a long connection path, easily leading to ignition failure or localized rich combustion; Second, while a fully open, shift-based diffusion flame scheme can improve stable combustion reliability, diffusion combustion leads to a significant increase in NOx and smoke emissions at low loads; Third, using a single-nozzle or few-nozzle load-carrying scheme causes severe circumferential temperature field unevenness, thereby inducing thermal stress, combustion oscillations, and worsening CO / UHC emissions. None of the above schemes achieves precise control of the head flow field, making it difficult to ensure ignition reliability and low-load stability while simultaneously achieving circumferential temperature field uniformity and low emission requirements.

[0004] Existing patent CN119042665A discloses a combustion chamber with a petal-shaped micro-diffusion nozzle structure. This solution optimizes the structure for the special combustion characteristics of hydrogen fuel, but does not address the combustion organization problems faced by axial staged combustion chambers during ignition and low-load stages. Therefore, it fails to solve the aforementioned defects such as poor ignition reliability, high emissions at low loads, and uneven temperature field.

[0005] Existing patent CN110878948A discloses an axial staged combustion chamber for a gas turbine and its control method. The central shift scheme adopted by this scheme still has the problems of long flame path and strong dependence on shift flame in the ignition and low load stages, and lacks active control means for the head flow field. Therefore, it fails to effectively solve key technical problems such as CO / UHC emission deterioration and thermoacoustic oscillation suppression under low load.

[0006] In summary, none of the existing patents mentioned above have effectively solved the problems existing in the prior art. Therefore, there is an urgent need for an axial staged combustion chamber fuel staged control method and system that can take into account ignition reliability, temperature field uniformity, wide operating condition stability and ultra-low emissions. Summary of the Invention

[0007] Based on the current state of the technology, this invention proposes an axial staged combustion chamber and a fuel staged control method and system to solve the problem that the existing axial staged combustion chamber is difficult to balance ignition reliability, temperature field uniformity, low emissions and combustion stability across the entire operating range, thereby achieving stable combustion and ultra-low emissions across the entire operating range.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a fuel grading control method for an axially graded combustion chamber is proposed, the specific technical solution of which is as follows: A fuel grading control method for an axially graded combustion chamber, wherein multiple premixed nozzles are arranged circumferentially at the head of the axially graded combustion chamber, and multiple secondary nozzles are arranged axially downstream. The multiple premixed nozzles are divided into a first premixing stage and a second premixing stage arranged at intervals. Each premixed nozzle is equipped with a standby diffuser nozzle, which is also divided into a first standby class and a second standby class. The multiple secondary nozzles are divided into at least two independently controlled sub-stages. The control method includes the following steps: Synchronized ignition and flame-integrated operation steps: Synchronously start the fuel supply of all premixed stages and duty personnel, and start the igniter to complete rapid flame-integration; Low-load switching and stable combustion steps: After successful ignition, the fuel supply to the second premix stage and the second shift worker is simultaneously shut off to achieve low-emission operation; Load ramp-up and restart procedure: When the load reaches the first threshold, the second premix stage fuel supply is restarted to meet the power demand. Axial first stage activation steps: When the load reaches the second threshold, the fuel supply to the first stage of the second stage nozzle is activated, initially realizing axial staged combustion; Optimization steps for shift workers: When the load reaches the third threshold, gradually shut off all shift workers' fuel to achieve a fully premixed combustion mode; Axial second stage activation steps: When the load reaches the fourth threshold, the fuel supply to the second stage of the secondary nozzle is activated to complete the full axial stage configuration.

[0009] Furthermore, in the load ramp-up and restart step, when the load reaches 10-20% of the rated load, the second premix stage second shift fuel supply is restarted, and combustion is maintained by all premix nozzles and their shift diffusion nozzles.

[0010] Furthermore, in the axial first stage activation step, when the load reaches 30-35% of the rated load, the first stage fuel supply of the secondary nozzle is activated, forming an axial staged combustion mode in which the head premix stage and the axial first stage work together.

[0011] Furthermore, in the duty shift optimization step, when the load reaches 40-45% of the rated load, the fuel supply of the first and second duty shifts is gradually shut off, so that the combustion chamber enters the fully premixed combustion mode.

[0012] Furthermore, in the duty shift optimization step, the fuel flow of the first and second duty shifts is gradually reduced using a ramp function until they are completely shut down.

[0013] Furthermore, in the axial second stage activation step, when the load reaches 70-80% of the rated load, the second stage fuel supply of the second stage nozzle is opened, completing the full activation of the axial second stage.

[0014] Furthermore, in each step, the pressure ratio of the fuel pressure supplied to the premixing nozzles of the first and second premixing stages to the air pressure at the combustion chamber head is 1.02-1.4.

[0015] Furthermore, in the synchronized ignition and flame-coupling step, all premixed nozzles complete flame-coupling within 100-200 milliseconds after the igniter is started.

[0016] To achieve the above objectives, according to a second aspect of the present invention, a fuel grading control system for an axially graded combustion chamber is proposed, the specific technical solution of which is as follows: A fuel grading control system for an axially graded combustion chamber, used to implement the above-mentioned fuel grading control method for the axially graded combustion chamber, includes: a fuel source, a fuel control module, a controller, a flame detector, a pressure sensor, a speed sensor, and a temperature sensor. The fuel control module includes a main fuel valve and multiple independent stage control valves. The inlet end of the main fuel valve is fluidly connected to the fuel output end of the fuel source, and the outlet end of the main fuel valve is fluidly connected to the inlet ends of the multiple stage control valves. The outlet ends of the multiple stage control valves are respectively fluidly connected to the fuel lines of each nozzle in the combustion chamber. The flame detector is installed at the head of the combustion chamber and is used to detect the flame status of the premixed nozzle and its associated shift diffuser nozzle. The speed sensor is installed in the gas turbine rotor system, and its signal output terminal is electrically connected to the controller to provide the controller with an engine load signal. The pressure sensor includes a fuel pressure sensor installed in the premixed fuel line and an air pressure sensor installed at the head of the combustion chamber, and its signal output terminal is electrically connected to the controller. The temperature sensor includes an exhaust temperature sensor disposed at the combustion chamber outlet and a wall temperature sensor disposed on the combustion chamber flame tube wall, and its signal output terminal is electrically connected to the controller. The controller is electrically connected to each stage control valve in the fuel control module, as well as the flame detector, the pressure sensor, the speed sensor, and the temperature sensor. The controller is configured to control the opening, closing, and opening degree adjustment of each stage control valve.

[0017] Furthermore, the plurality of staged control valves include: The first premix stage control valve has its outlet end connected to the premix nozzle fuel line of the first premix stage. The second premixing stage control valve has its outlet end connected to the premixing nozzle fuel line of the second premixing stage. The first duty officer's control valve has its outlet end connected to the fuel line of the first duty officer's diffuser nozzle. The second duty control valve has its outlet end connected to the fuel line of the second duty diffuser nozzle. The first-stage axial control valve has its outlet end connected to the first-stage fuel line of the second-stage nozzle. The axial second-stage control valve has its outlet end connected to the second-stage fuel line of the second-stage nozzle.

[0018] Furthermore, the controller adjusts the opening of the first premix stage control valve and the second premix stage control valve in real time based on the fuel pressure and air pressure signals fed back by the pressure sensor, so that the pressure ratio of the fuel pressure supplied to the premix nozzle to the air pressure at the head of the combustion chamber is 1.02-1.4.

[0019] To achieve the above objectives, according to a third aspect of the present invention, an axially staged combustion chamber is proposed, the specific technical solution of which is as follows: An axially staged combustion chamber, comprising: The combustion chamber head has multiple premixed nozzles arranged circumferentially, and the multiple premixed nozzles are divided into a first premixing stage and a second premixing stage arranged at intervals. Multiple duty diffusion nozzles are configured in a one-to-one correspondence with the premixed nozzle, and the multiple duty diffusion nozzles are divided into a first duty class and a second duty class. A combustion chamber flame tube is located downstream of the combustion chamber head and is used to accommodate the combustion zone; Multiple secondary nozzles are disposed axially downstream of the premixed nozzle, and the multiple secondary nozzles are divided into at least two independently controlled fuel sub-stages, including a first sub-stage and a second sub-stage.

[0020] Furthermore, the swirl directions of the premixing nozzles in the first premixing stage and the second premixing stage are generally opposite.

[0021] Furthermore, in the nozzles of the first premixing stage, at least two nozzles have the same swirl direction, and at least one nozzle has the same swirl direction as the nozzle of the second premixing stage, so that there are both reverse swirl shearing zone and co-directional swirl merging zone in the circumferential direction of the combustion chamber head.

[0022] Furthermore, it also includes an igniter disposed at the outer edge of a premix nozzle of the first premix stage.

[0023] By applying the above-described technical solution of the present invention, at least the following technical effects are achieved: 1. This invention achieves uniform flame propagation without dependence on a central nozzle by simultaneously igniting all premixed stages and standby fuels. After the igniter ignites a single nozzle, the flame quickly spreads to all nozzles, completely eliminating the risk of ignition failure caused by the long flame path in traditional solutions. At the same time, it ensures the uniformity of the circumferential temperature field at the head of the combustion chamber at the moment of ignition, avoiding instantaneous high emissions caused by localized rich fuel combustion.

[0024] 2. This invention completely eliminates the diffusion combustion of the second premixing stage and its shift in the low-load stage, significantly reducing NOx and smoke emissions by synchronously shutting down the second premixing stage and its shift in the medium-to-high-load stage; in the medium-to-high-load stage, all shifts in the medium-to-high-load stage are gradually shut down to achieve a fully premixed combustion mode, further suppressing the formation of thermal NOx; at the same time, through axial staged fuel input, local high-temperature and low-temperature zones are avoided, synergistically reducing CO and UHC emissions, and meeting the environmental protection requirements under all operating conditions.

[0025] 3. This invention, through the design of the first and second premixing stages with opposite swirl directions, forms a spatiotemporally asymmetric flow field in the combustion chamber. In the circumferential direction, there are simultaneously opposing swirl shearing zones and co-directional swirl merging zones. The multi-scale vortex systems interfere with each other, effectively disrupting the thermoacoustic coupling conditions, suppressing combustion oscillations, and ensuring the dynamic stability of the combustion system over a wide load range.

[0026] 4. The spaced nozzles and staged fuel injection strategy of this invention make the heat load distribution in the combustion zone uniform, avoid local thermal stress concentration, and extend the service life of the combustion chamber and turbine components; multi-level fine control ensures smooth switching between ignition, low load, load ramp-up, axial staged and full premixed modes, eliminates the risk of combustion oscillation and flameout, and gives the combustion chamber excellent adaptability to all operating conditions.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic flowchart of a fuel grading control method for an axially graded combustion chamber proposed in this invention is shown. Figure 2 A schematic diagram illustrating an example of the axial staged combustion chamber nozzle arrangement in the first aspect of the present invention is provided. Figure 3 A schematic diagram of the fuel grading control system for an axially graded combustion chamber proposed in this invention is shown. Figure 4 A schematic diagram of an axially staged combustion chamber proposed in this invention is shown; Figure 5 A schematic diagram of a computer system architecture required for the execution of a computer program as proposed in this application is shown; Figure 6 A schematic diagram of the hardware structure of an electronic device proposed in this application is shown. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0031] To address the challenges of achieving ignition reliability, temperature field uniformity, low emissions, and combustion stability across all operating conditions in existing axial staged combustors, this application proposes an axial staged combustor and a fuel staged control method and system. This system involves grouping the head premixed nozzles at unequal intervals and equipping them with independent standby diffuser nozzles. At the moment of ignition, all head fuel supplies are simultaneously activated to achieve rapid and uniform flame. After successful ignition, one group of premixed nozzles and its corresponding standby diffuser nozzles are immediately shut off to reduce low-load emissions. As the load increases, this group of fuels is sequentially reopened, and the axial secondary nozzles are introduced in stages. Simultaneously, by setting the two groups of nozzles to rotate in opposite directions, a spatiotemporally asymmetric flow field is created to suppress thermoacoustic oscillations. During medium- and high-load stages, all standby diffuser nozzles are gradually shut off to achieve fully premixed combustion. This achieves synergistic optimization of ignition reliability, temperature field uniformity, low emissions, and high stability across all operating conditions.

[0032] The first aspect of this application proposes a fuel grading control method for an axially graded combustion chamber. By grouping the head premixed nozzles at unequal intervals and matching them with independent duty diffuser nozzles, a control sequence is adopted, which includes synchronous full-open flame, closing one group and its duty after successful ignition, reopening when the load increases, and grading the activation of the axial secondary nozzles under high load. Combined with a reverse rotation design and a duty full-shutdown strategy, rapid flame, low emissions, and high stable combustion are achieved across the entire operating range.

[0033] See Figure 1 As shown, this application proposes a fuel grading control method for an axially graded combustion chamber. This method is applied to an axially graded combustion chamber with multiple premixed nozzles arranged circumferentially at the head and multiple secondary nozzles arranged axially downstream. The multiple premixed nozzles are divided into two independent fuel supply groups, comprising a first premixed stage and a second premixed stage arranged at intervals. The first and second premixed stages are designed with opposite swirl directions. Each premixed nozzle is paired with a standby diffuser nozzle, corresponding to a first standby group and a second standby group. The multiple secondary nozzles are divided into at least two independently controlled fuel sub-stages, including a first sub-stage and a second sub-stage.

[0034] See Figure 2 As shown, this embodiment uses a combustion chamber head with five premixed nozzles arranged circumferentially as an example for detailed explanation. The five premixed nozzles are numbered J1, J2, J3, J4, and J5 in circumferential order, where J1, J3, and J4 belong to the first premixing stage O1, and J2 and J5 belong to the second premixing stage O2. The swirl direction of each premixed nozzle is configured as follows: premixed nozzles J1 and J3 of the first premixing stage swirl clockwise, while premixed nozzles J2 and J5 of the second premixing stage swirl counterclockwise. Premixed nozzle J4 of the first premixing stage is also configured to swirl counterclockwise. Each premixed nozzle is paired with a standby diffuser nozzle, corresponding to a first standby stage OP1 and a second standby stage OP2. The igniter is located on the outer edge of nozzle J1 of the first premixing stage. A secondary nozzle is arranged axially downstream, divided into two independently controlled fuel sub-stages: the first sub-stage and the second sub-stage.

[0035] Based on the above combustion chamber structure, this application proposes a fuel grading control method for an axially graded combustion chamber, which includes the following steps: Synchronized ignition and flame-integrated operation steps: Synchronously start the fuel supply of all premixed stages and duty personnel, and start the igniter to complete rapid flame-integration; Low-load switching and stable combustion steps: After successful ignition, the fuel supply to the second premix stage and the second shift worker is simultaneously shut off to achieve low-emission operation; Load ramp-up and restart procedure: When the load reaches the first threshold, the second premix stage fuel supply is restarted to meet the power demand. Axial first stage activation steps: When the load reaches the second threshold, the fuel supply of the first stage of the second stage nozzle is opened, and axial staged combustion is initially realized; Optimization steps for shift workers: When the load reaches the third threshold, gradually shut off all shift worker fuels to achieve a fully premixed combustion mode; Axial second stage activation steps: When the load reaches the fourth threshold, the fuel supply to the second stage of the secondary nozzle is activated to complete the full axial stage configuration.

[0036] The above-mentioned synchronized ignition and flame-co-firing steps include: Specifically, after the engine starting system issues an ignition command, it supplies fuel to all head premixed nozzles and their associated standby diffusers, and sends an ignition signal to the igniter. Since the igniter is located at the outer edge of the premixed nozzle J1 in the first premixing stage, it first ignites the fuel-air mixture ejected from the premixed nozzles and standby diffusers near premixed nozzle J1, forming a stable flame. This flame, acting as a stable ignition source, rapidly propagates along the circumferential space of the combustion chamber head, sequentially igniting adjacent premixed nozzles J2 and J5 and their associated standby diffusers; the ignited J2 and J5 then further ignite the remaining premixed nozzles J3 and J4 and their associated standby diffusers. Within 100-200 milliseconds, all premixed nozzles and their associated standby diffusers are ignited, forming a stable and uniform annular flame composed of all standby flames and premixed flames. By simultaneously igniting all premixed stages and standby fuels, the flame-connecting time is greatly shortened, avoiding the risk of ignition failure due to the difficulty of propagating the premixed flame alone. At the same time, all premixed nozzles and their standby diffusers ignite simultaneously, ensuring the uniformity of the circumferential temperature field at the head of the combustion chamber at the moment of ignition, eliminating the instantaneous high emissions caused by localized rich combustion in traditional schemes. The establishment of the standby flame also provides stable flame support for subsequent low-load operation, laying the foundation for stable combustion under all operating conditions.

[0037] The above-mentioned low-load switching and stable combustion steps include: Specifically, once all premixed nozzles and their associated standby diffuser nozzles have successfully ignited and the flame signal is stable, the fuel supply to the second premixed stage and its associated second standby stage is simultaneously cut off. At this time, the combustion chamber operates only with the spaced-apart first premixed stage and its associated first standby stage, with stable combustion maintained by the premixed nozzles of the first premixed stage and their associated diffuser nozzles. By simultaneously shutting down the second premixed stage and its associated second standby stage, the combustion reaction in this area is eliminated, avoiding the problem of increased NOx and smoke emissions due to standby diffuser combustion under low load. Since the premixed nozzles of the first premixed stage are spaced-apart, the resulting premixed flame and standby flame support each other, enabling stable combustion to be maintained without the participation of the second premixed stage, ensuring combustion efficiency under low load conditions. At the same time, the synchronous shutdown strategy simplifies the control logic, avoids the risk of partial flameout that may be caused by sequential shutdown, and lays a stable flame foundation for subsequent load increases.

[0038] The above-mentioned load ramp-up and restart steps include: Specifically, when the engine load reaches between 10% and 20% of the rated load, the fuel supply to the second premixed stage and its associated second shift nozzle is restored. At this time, all head premixed nozzles and their associated shift diffuser nozzles are engaged, and combustion is maintained jointly by all premixed nozzles and their shift diffuser nozzles. During the critical stage of load increase, the second premixed stage is reactivated to increase the heat release density of the combustion chamber, meeting the fuel quantity required for the increased load; simultaneously, the associated second shift nozzle is activated, and its shift flame provides a stable ignition source for the newly added premixed fuel in the second premixed stage, ensuring complete combustion of the new fuel and preventing localized flameout or combustion oscillations caused by a sudden increase in fuel. The selection of this load threshold (10-20%) ensures that the low-emission operating time is sufficiently long during the low-load stage, while also ensuring sufficient combustion margin in the combustion chamber before entering higher loads, laying the foundation for subsequent axial stage activation.

[0039] The above-mentioned first-stage axial deployment steps include: Specifically, when the engine load reaches between 30% and 35% of the rated load, fuel is supplied to the first stage of the axially downstream secondary nozzle. At this time, some fuel is transferred from the head premixed nozzle to the downstream secondary nozzle for combustion, forming an axial staged combustion mode in which the first and second premixed stages work together with the axial first stage. By introducing the first stage, some combustion release is transferred to the downstream region, avoiding local high temperatures caused by excessively rich fuel in the head premixed stage, thereby suppressing the formation of thermal NOx. At the same time, the synergistic effect of the two combustion zones of the premixed stage and the axial first stage expands the flame distribution range, making the heat load distribution in the combustion chamber more uniform, creating conditions for the subsequent introduction of the second stage and operation at higher loads. The selection of this load threshold (30-35%) ensures that the head premixed stage has sufficiently high temperature and pressure when the first stage is introduced, ensuring reliable ignition of the downstream fuel.

[0040] The above-mentioned steps for optimizing duty shifts include: Specifically, once the engine load reaches 40% of its rated load and combustion stabilizes, the fuel flow of the first and second premixed stages is gradually reduced using a ramp function until they are completely shut off, thoroughly cutting off the fuel supply to all premixed diffuser nozzles. The combustion chamber operates jointly by the first and second premixed stages at the head and the first axial stage, maintaining a fully premixed combustion state and laying the foundation for the subsequent activation of the second stage. During this process, because the premixed nozzles of the first and second premixed stages are designed with opposite swirling directions, a reverse swirling shear zone and a co-directional swirling merging zone exist simultaneously in the circumferential direction of the combustion chamber head. This creates a spatiotemporally asymmetric flow and temperature field within the combustion chamber, with each vortex system interfering with the others, effectively suppressing the conditions for the establishment of thermoacoustic oscillations.

[0041] This step gradually shuts down all standby diffusion nozzles during the medium-load stage, allowing the combustion chamber to enter a fully premixed combustion mode, completely eliminating NOx generated by diffusion combustion and reducing NOx emissions to extremely low levels. Through the overall opposite swirl direction design of the first and second premixed stages, a stable premixed flame can be maintained even without standby flame support, solving the problem of traditional solutions still relying on standby flames at high loads, which leads to continuous NOx generation. During the standby shutdown process, the fuel flow rate is gradually reduced to avoid the risk of flameout that may be caused by a sudden drop in fuel flow rate, ensuring a smooth and reliable transition from standby mode to fully premixed mode.

[0042] Throughout all the above steps, the pressure ratio of the fuel pressure supplied to the premixing nozzles of the first and second premixing stages to the air pressure at the combustion chamber head is maintained between 1.02 and 1.4. Preferably, this pressure ratio is maintained between 1.05 and 1.25. This pressure ratio range ensures sufficient fuel injection velocity to prevent backfire while avoiding the risk of fuel auto-ignition due to excessive pressure, thus ensuring safe and reliable premixed combustion across the entire operating range.

[0043] The above-mentioned axial second-stage deployment steps include: Specifically, when the engine load reaches 70-80%, fuel is supplied to the second stage of the secondary nozzle located downstream of the axial direction, completing the full engagement of the second stage of the axial combustion. At this time, both the first and second stages of the secondary nozzle are in operation, forming a complete axial staged combustion mode together with the first and second premixed stages at the head.

[0044] This step, building upon the already achieved fully premixed combustion, further transfers some fuel from the head premixing stage to the downstream secondary nozzles through the introduction of the second stage. This maintains the head premixing stage in a relatively lean state under higher loads, continuously suppressing the formation of thermal NOx. The staged introduction of the first and second stages ensures a smooth transition in fuel quantity changes, avoiding combustion oscillations caused by a single large fuel injection. Simultaneously, this staged strategy enables the combustion chamber to maintain optimized combustion temperature and stoichiometric ratio distribution over a wide load range, achieving a synergy between low emissions and high combustion efficiency, laying the foundation for subsequent shift optimization steps.

[0045] A second aspect of this application proposes a fuel grading control system for an axially graded combustion chamber, used to implement the fuel grading control method for the axially graded combustion chamber proposed in the first aspect above. (See reference...) Figure 3 As shown, the fuel grading control system includes a flame detector, a speed sensor, a temperature sensor, a pressure sensor, a controller, a fuel source, and a fuel control module. The signal output terminals of the flame detector, speed sensor, temperature sensor, and pressure sensor are respectively connected to the signal input terminal of the controller; the control signal output terminal of the controller is connected to the control signal input terminal of the fuel control module; the fuel output terminal of the fuel source is fluidly connected to the fuel input terminal of the fuel control module; and the fuel output terminal of the fuel control module is fluidly connected to the fuel lines of each nozzle in the combustion chamber.

[0046] Specifically, the fuel control module includes a main control valve and multiple independent stage control valves. The main control valve is fluidly connected to the inlet of each stage control valve, controlling the on / off state of the fuel main and the total flow rate. The outlets of the multiple independent stage control valves are fluidly connected to the fuel lines of each nozzle in the combustion chamber. In this embodiment, the multiple independent stage control valves specifically include: a first premixing stage control valve, whose outlet is connected to the fuel line of the premixing nozzle of the first premixing stage; a second premixing stage control valve, whose outlet is connected to the fuel line of the premixing nozzle of the second premixing stage; a first shift control valve, whose outlet is connected to the fuel line of the shift diffusion nozzle of the first shift; a second shift control valve, whose outlet is connected to the fuel line of the shift diffusion nozzle of the second shift; an axial first sub-stage control valve, whose outlet is connected to the first sub-stage fuel line of the second stage nozzle; and an axial second sub-stage control valve, whose outlet is connected to the second sub-stage fuel line of the second stage nozzle. Each stage control valve uses an independently adjustable solenoid valve or proportional valve. Its control signal input terminal is electrically connected to the controller, enabling precise control of fuel flow according to the controller's instructions, including fuel opening and closing, as well as continuous flow regulation.

[0047] Specifically, a flame detector is installed at the head of the combustion chamber to monitor the flame status of each premixed nozzle and its associated shift diffuser nozzle in real time. The signal output terminal of the flame detector is electrically connected to the controller, feeding back the detected flame signal to the controller in real time as a basis for determining whether ignition was successful and the stability of the flame. In this embodiment, the flame detector may be one or a combination of an ultraviolet flame detector, an ionization flame detector, or a photoelectric sensor.

[0048] Specifically, the pressure sensors include fuel pressure sensors and air pressure sensors. The fuel pressure sensors are installed in the fuel lines of each premixing stage to monitor the fuel pressure supplied to the premixing nozzles in real time; the air pressure sensors are installed at the combustion chamber head to monitor the head air pressure in real time. The signal output terminals of each pressure sensor are electrically connected to the controller, feeding back the detected pressure signals to the controller in real time to provide a basis for pressure ratio control.

[0049] Specifically, a speed sensor is installed in the gas turbine rotor system to monitor the engine speed in real time. The signal output terminal of the speed sensor is electrically connected to the controller, feeding back the detected speed signal to the controller in real time. The controller calculates the current engine load based on the speed signal, which serves as the basis for determining the execution of load-related steps.

[0050] Specifically, the temperature sensors include an exhaust temperature sensor and a combustion chamber wall temperature sensor. The exhaust temperature sensor is located at the combustion chamber outlet or turbine inlet to monitor the exhaust temperature in real time; the combustion chamber wall temperature sensor is located on the combustion chamber flame tube wall to monitor the wall temperature in real time. The signal output terminals of each temperature sensor are electrically connected to the controller, feeding back the detected temperature signals to the controller in real time as an auxiliary basis for judging combustion stability and combustion status.

[0051] Specifically, the controller is connected to the flame detector, pressure sensor, speed sensor, temperature sensor, and each fuel control module. The controller receives flame signals from the flame detector, pressure signals from the pressure sensor, speed signals from the speed sensor, temperature signals from the temperature sensor, and external load commands, and issues control commands to the fuel control modules according to preset control logic. The controller is configured to execute the steps of the fuel grading control method described in the first aspect, specifically including: upon receiving an ignition command, the controller simultaneously issues opening commands to the first premixed stage control valve, the second premixed stage control valve, the first shift control valve, and the second shift control valve, and sends an ignition signal to the igniter to achieve synchronous ignition and flame linkage; when the flame sensor detects that all premixed nozzles and their associated shift diffusers have been successfully ignited and the flame signal is stable, the controller issues closing commands to the second premixed stage control valve and the second shift control valve, synchronously cutting off the fuel supply to the second premixed stage and its associated second shift, achieving low-load switching and stable combustion; when the engine load calculated from the speed signal fed back by the speed sensor reaches between 10% and 20% of the rated load, the controller issues a closing command to the first premixed stage control valve, the second premixed stage control valve, the first shift diffuser control valve, and the second shift control valve, and sends an ignition signal to the igniter to achieve synchronous ignition and flame linkage; The second premixing stage control valve and the second shift control valve issue an opening command to restore fuel supply, enabling load ramp-up and restart. When the engine load reaches 30% to 35% of the rated load, the controller issues an opening command to the axial first-stage control valve, supplying fuel to the first stage of the secondary nozzle, thus engaging the axial first stage. After the engine load reaches 40% of the rated load and combustion stabilizes, the controller issues a gradual closing command to the first and second shift control valves, reducing their opening degree using a ramp function until they are completely closed, optimizing shift operation. When the engine load reaches 70-80% to the basic rated load, the controller issues an opening command to the axial second-stage control valve, supplying fuel to the second stage of the secondary nozzle, completing the engagement of the axial second stage. During the above control process, the controller also adjusts the opening degree of each premixing stage control valve in real time based on fuel pressure and air pressure signals fed back from pressure sensors, maintaining the pressure ratio between the fuel pressure supplied to the premixing nozzle and the air pressure at the combustion chamber head between 1.02 and 1.4.

[0052] The fuel grading control system of the axially graded combustor described above enables precise and proactive regulation of the fuel supply to the axially graded combustor, providing complete hardware support for the fuel grading control method of the axially graded combustor described in the first aspect, and ensuring the synergistic optimization of ignition reliability, temperature field uniformity, low emissions and combustion stability across the entire operating range.

[0053] A third aspect of this application proposes an axial staged combustor for a gas turbine, used to implement the fuel staged control method for the axial staged combustor of a gas turbine described in the first aspect, and in conjunction with the fuel staged control system for the axial staged combustor of a gas turbine described in the second aspect. (See also...) Figure 4 As shown, the axial staged combustion chamber of the gas turbine includes: a combustion chamber head, a combustion chamber flame tube, multiple premixed nozzles, an igniter, multiple standby diffuser nozzles, and multiple secondary nozzles.

[0054] Specifically, the combustion chamber head is located at the upstream end of the combustion chamber and is used to install the premixed nozzles and the standby diffuser nozzles. The combustion chamber head is fixedly connected to the combustion chamber casing and is equipped with an air inlet passage for introducing compressed air from the compressor.

[0055] Specifically, multiple premixed nozzles are circumferentially arranged at the head of the combustion chamber, with a total number of premixed nozzles N≥5. These premixed nozzles are divided into two independent fuel supply groups, comprising a first premixing stage and a second premixing stage arranged at intervals. The first and second premixing stages are designed with opposite swirl directions to create a spatiotemporally asymmetric flow and temperature field within the combustion chamber to suppress thermoacoustic oscillations.

[0056] Specifically, the igniter is located on the outer edge of one of the premixed nozzles in the first premixed stage and is fixed to the head baffle of the combustion chamber by a mounting base. Its electrode extends into the combustion zone and its relative position with the premixed nozzle meets the requirements for ignition energy propagation. It is used to ignite the fuel-air mixture at the moment of ignition and start the combustion process.

[0057] Specifically, multiple shift diffusion nozzles are configured in a one-to-one correspondence with the premixing nozzles. Each premixing nozzle has a shift diffusion nozzle located at its center or side, and these shift diffusion nozzles are divided into a first shift class and a second shift class. The first shift class includes the shift diffusion nozzles that correspond to the premixing nozzles of the first premixing stage, and the second shift class includes the shift diffusion nozzles that correspond to the premixing nozzles of the second premixing stage.

[0058] Specifically, multiple secondary nozzles are positioned axially downstream of the premixed nozzle and arranged circumferentially above the head baffle of the secondary combustion chamber. These secondary nozzles are divided into at least two independently controlled fuel sub-stages, including a first sub-stage and a second sub-stage, for staged injection during load increases to achieve axial staged combustion.

[0059] Specifically, the combustion chamber flame tube includes a primary combustion chamber flame tube and a secondary combustion chamber flame tube. The primary combustion chamber flame tube is located downstream of the combustion chamber head and is used to accommodate the head combustion zone formed by the first and second premixing stages. The secondary combustion chamber flame tube is located downstream of the primary combustion chamber flame tube and is connected to the secondary nozzle, used to accommodate the axially staged combustion zone. The outlet end of the combustion chamber flame tube is connected to the turbine inlet through the combustion chamber transition section.

[0060] The fuel lines of each component of the combustion chamber are respectively fluidly connected to the outlet of each stage control valve of the fuel control module described in the second aspect, specifically including: the fuel line of the premixing nozzle of the first premixing stage is connected to the first premixing stage control valve; the fuel line of the premixing nozzle of the second premixing stage is connected to the second premixing stage control valve; the fuel line of the shift diffuser nozzle of the first shift is connected to the first shift control valve; the fuel line of the shift diffuser nozzle of the second shift is connected to the second shift control valve; the first sub-stage fuel line of the second stage nozzle is connected to the axial first sub-stage control valve; and the second sub-stage fuel line of the second stage nozzle is connected to the axial second sub-stage control valve.

[0061] In addition, the combustion chamber head and fuel pipeline are equipped with various sensor interfaces that cooperate with the control system described in the second aspect, for installing detection elements such as flame detectors, pressure sensors, and temperature sensors.

[0062] Through the above structural design, the gas turbine axial staged combustion chamber proposed in this application, in conjunction with the control system of the second aspect, achieves synchronous ignition and rapid flame connection, low-load and low-emission operation, axial staged combustion, and fully premixed combustion mode through the control method of the first aspect, taking into account ignition reliability, temperature field uniformity, low emissions, and combustion stability across the entire operating range.

[0063] According to a fourth aspect of this application, a computer program product is provided, comprising a computer program. When the computer program is executed by a processor, it is capable of implementing the aforementioned fuel grading control method for an axially graded combustion chamber.

[0064] Figure 5 A schematic block diagram of a computer system 500 that can be used to run the computer program is shown. This computer system 500 can serve as an example of a hardware environment for performing the methods described above.

[0065] It should be noted that, Figure 5 The computer system 500 shown is merely an example and should not be construed as limiting the functionality and scope of this application.

[0066] See Figure 5As shown, the computer system 500 includes a central processing unit (CPU) 501, which can perform various appropriate actions and processes based on programs stored in read-only memory (ROM) 502 or programs loaded from storage section 508 into random access memory (RAM). The RAM 503 also stores various programs and data required for system operation. The CPU 501, ROM 502, and RAM 503 are interconnected via a bus 504. An input / output interface 505 (I / O interface) is also connected to the bus 504.

[0067] The following components are connected to the input / output interface 505: an input section 506 including a keyboard, mouse, etc.; an output section 507 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 508 including a hard disk, etc.; and a communication section 509 including a network interface card such as a local area network card, modem, etc. The communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to the input / output interface 505 as needed. A removable medium 511, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 510 as needed so that computer programs read from it can be installed into the storage section 508 as needed.

[0068] Specifically, according to embodiments of this application, the processes described in the various method flowcharts can be implemented as computer software programs. For example, embodiments of this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 509, and / or installed from a removable medium. When the computer program is executed by central processing unit 501, it performs various functions defined in the system of this application.

[0069] According to a fifth aspect of this application, an electronic device is also provided. This embodiment will be described using this electronic device as an example of a terminal device. Figure 6 As shown, the electronic device includes a memory 602 and a processor 604. The memory 602 stores a computer program, and the processor 604 is configured to execute the fuel grading control method of the axial grading combustion chamber described above through the computer program.

[0070] Optionally, in this embodiment, the aforementioned electronic device may be located in at least one of a plurality of network devices in a computer network.

[0071] Alternatively, as those skilled in the art will understand, Figure 6 The structure shown is for illustrative purposes only. Figure 6 This does not limit the structure of the aforementioned electronic devices. For example, the electronic device may also include components that are more... Figure 6 The more or fewer components shown (such as network interfaces, etc.), or having the same Figure 6 The different configurations shown.

[0072] The memory 602 can be used to store software programs and modules, such as the corresponding program instructions / modules in the fuel grading control method of the axial grading combustion chamber described above in this application. The processor 604 executes various functional applications and data processing by running the software programs and modules stored in the memory 602. The memory 602 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. Specifically, the memory 602 may be used, but is not limited to, storing collected test data, flow parameters, and processing results. As an example, such as... Figure 6 As shown, the memory 602 may include, but is not limited to, the modules in the fuel grading control system of the axially oriented combustion chamber. Other module units may also be included, which will not be described in detail in this example.

[0073] Optionally, the transmission device 606 described above is used to receive or send data via a network. Specific examples of the network described above may include wired networks and wireless networks.

[0074] In addition, the aforementioned electronic device also includes: a display 608 for displaying the aforementioned test data and processing results; and a connection bus 610 for connecting the various module components in the aforementioned electronic device.

[0075] According to a sixth aspect of this application, a computer-readable storage medium is provided, wherein a processor of an electronic device reads computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the aforementioned fuel grading control method for an axially graded combustion chamber.

[0076] Optionally, in this embodiment, those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing the hardware related to the terminal device. The program can be stored in a computer-readable storage medium, which may include: flash drive, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc.

[0077] The above are merely several specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0079] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A fuel grading control method for an axially staged combustion chamber, wherein a plurality of premixing nozzles are arranged circumferentially at the head of the axially staged combustion chamber, and a plurality of secondary nozzles are arranged axially downstream, characterized in that, The plurality of premixed nozzles are divided into a first premixing stage and a second premixing stage arranged at intervals. Each premixed nozzle is equipped with a standby diffusion nozzle, and correspondingly divided into a first standby stage and a second standby stage. The plurality of secondary nozzles are divided into at least two independently controlled sub-stages. The control method includes the following steps: Synchronized ignition and flame-integrated operation steps: Synchronously start the fuel supply of all premixed stages and duty personnel, and start the igniter to complete rapid flame-integration; Low-load switching and stable combustion steps: After successful ignition, the fuel supply to the second premix stage and the second shift worker is simultaneously shut off to achieve low-emission operation; Load ramp-up and restart procedure: When the load reaches the first threshold, the second premix stage fuel supply is restarted to meet the power demand. Axial first stage activation steps: When the load reaches the second threshold, the fuel supply to the first stage of the second stage nozzle is activated, initially realizing axial staged combustion; Optimization steps for shift workers: When the load reaches the third threshold, gradually shut off all shift workers' fuel to achieve a fully premixed combustion mode; Axial second stage activation steps: When the load reaches the fourth threshold, the fuel supply to the second stage of the secondary nozzle is activated to complete the full axial stage configuration.

2. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, During the load ramp-up and restart step, when the load reaches 10-20% of the rated load, the second premix stage second shift fuel supply is restarted, and combustion is maintained by all premix nozzles and their shift diffusion nozzles.

3. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, In the axial first stage activation step, when the load reaches 30-35% of the rated load, the first stage fuel supply of the secondary nozzle is activated, forming an axial staged combustion mode in which the head premix stage and the axial first stage work together.

4. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, In the duty shift optimization step, when the load reaches 40-45% of the rated load, the fuel supply of the first and second duty shifts is gradually shut off, so that the combustion chamber enters the fully premixed combustion mode.

5. The fuel grading control method for an axially graded combustion chamber according to claim 4, characterized in that, In the duty shift optimization step, the fuel flow of the first and second duty shifts is gradually reduced using a ramp function until they are completely shut down.

6. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, In the axial second stage activation step, when the load reaches 70-80% of the rated load, the second stage fuel supply of the second stage nozzle is opened, completing the full activation of the axial second stage.

7. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, In each step, the pressure ratio of the fuel pressure supplied to the premixing nozzles of the first and second premixing stages to the air pressure at the combustion chamber head is 1.02-1.

4.

8. The fuel grading control method for an axially graded combustion chamber according to claim 1, characterized in that, In the synchronized ignition and flame-coupling step, all premixed nozzles complete flame-coupling within 100-200 milliseconds after the igniter is started.

9. A fuel grading control system for an axially graded combustion chamber, used to implement the fuel grading control method for an axially graded combustion chamber as described in any one of claims 1-8, characterized in that, include: Fuel source, fuel control module, controller, flame detector, pressure sensor, speed sensor and temperature sensor; The fuel control module includes a main fuel valve and multiple independent stage control valves. The inlet end of the main fuel valve is fluidly connected to the fuel output end of the fuel source, and the outlet end of the main fuel valve is fluidly connected to the inlet ends of the multiple stage control valves. The outlet ends of the multiple stage control valves are respectively fluidly connected to the fuel lines of each nozzle in the combustion chamber. The flame detector is installed at the head of the combustion chamber and is used to detect the flame status of the premixed nozzle and its associated shift diffuser nozzle. The speed sensor is installed in the gas turbine rotor system, and its signal output terminal is electrically connected to the controller to provide the controller with an engine load signal. The pressure sensor includes a fuel pressure sensor installed in the premixed fuel line and an air pressure sensor installed at the head of the combustion chamber, and its signal output terminal is electrically connected to the controller. The temperature sensor includes an exhaust temperature sensor disposed at the combustion chamber outlet and a wall temperature sensor disposed on the combustion chamber flame tube wall, and its signal output terminal is electrically connected to the controller. The controller is electrically connected to each stage control valve in the fuel control module, as well as the flame detector, the pressure sensor, the speed sensor, and the temperature sensor. The controller is configured to control the opening, closing, and opening degree adjustment of each stage control valve.

10. The fuel grading control system for the axially graded combustion chamber according to claim 9, characterized in that, The plurality of staged control valves include: The first premix stage control valve has its outlet end connected to the premix nozzle fuel line of the first premix stage. The second premixing stage control valve has its outlet end connected to the premixing nozzle fuel line of the second premixing stage. The first duty officer's control valve has its outlet end connected to the fuel line of the first duty officer's diffuser nozzle. The second duty control valve has its outlet end connected to the fuel line of the second duty diffuser nozzle. The first-stage axial control valve has its outlet end connected to the first-stage fuel line of the second-stage nozzle. The axial second-stage control valve has its outlet end connected to the second-stage fuel line of the second-stage nozzle.

11. The fuel grading control system for the axially graded combustion chamber according to claim 9, characterized in that: The controller adjusts the opening of the first premix stage control valve and the second premix stage control valve in real time based on the fuel pressure and air pressure signals fed back by the pressure sensor, so that the pressure ratio of the fuel pressure supplied to the premix nozzle to the air pressure at the head of the combustion chamber is 1.02-1.

4.

12. An axially staged combustion chamber, characterized in that, include: The combustion chamber head has multiple premixed nozzles arranged circumferentially, and the multiple premixed nozzles are divided into a first premixing stage and a second premixing stage arranged at intervals. Multiple duty diffusion nozzles are configured in a one-to-one correspondence with the premixed nozzle, and the multiple duty diffusion nozzles are divided into a first duty class and a second duty class. A combustion chamber flame tube is located downstream of the combustion chamber head and is used to accommodate the combustion zone; Multiple secondary nozzles are disposed axially downstream of the premixed nozzle, and the multiple secondary nozzles are divided into at least two independently controlled fuel sub-stages, including a first sub-stage and a second sub-stage.

13. The axially staged combustion chamber according to claim 12, characterized in that, The swirl directions of the premixing nozzles in the first premixing stage and the second premixing stage are generally opposite.

14. The axially staged combustion chamber according to claim 12, characterized in that, In the nozzles of the first premixing stage, at least two nozzles have the same swirl direction, and at least one nozzle has the same swirl direction as the nozzle of the second premixing stage, so that there are both reverse swirl shearing zone and co-directional swirl merging zone in the circumferential direction of the combustion chamber head.

15. The axially staged combustion chamber according to claim 12, characterized in that, It also includes an igniter disposed at the outer edge of a premix nozzle of the first premix stage.

16. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the fuel grading control method for the axially graded combustion chamber as described in any one of claims 1 to 8.

17. An electronic device comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to execute the fuel grading control method for the axially graded combustion chamber according to any one of claims 1 to 8 through the computer program.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein the computer program can be executed by an electronic device to perform the fuel grading control method for the axially graded combustion chamber according to any one of claims 1 to 8.

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