GAS TURBINE COMBUSTION CHAMBER SYSTEM AND METHOD FOR OPERATING A GAS TURBINE COMBUSTION CHAMBER SYSTEM

Description

[0001] The invention relates to a gas turbine combustion chamber system, in particular a micro gas turbine combustion chamber system, comprising a combustion chamber having a longitudinally extending flame tube surrounding a flame zone, which is provided with a burner on its inlet side and is coupled or can be coupled to a turbine arrangement on its outlet side facing away from the burner and is provided with mixed air openings in an outlet section, comprising a pressure housing surrounding the combustion chamber, between the inside of which and the outside of the flame tube for supplying an air mass flow, an inflow channel is formed leading from the outlet side to the inlet side, via which a mixed air portion is fed via the mixed air openings into the interior of the flame tube and a burner air portion is fed to the burner for combustion with the inflowing fuel, and comprising a control device via which the burner air portion supplied to the burner can be controlled,by varying the mixed air portion depending on the load point of the turbine arrangement by adjusting the clear flow width of the mixed air openings. Furthermore, the invention relates to a method for operating a gas turbine combustion chamber system, in particular a micro gas turbine combustion chamber system, according to one of the preceding claims, in which an air mass flow is supplied via an inflow channel between the inside of a surrounding pressure casing and the outside of a flame tube from the outlet side thereof and is divided by means of mixed air openings arranged in an outlet section of the flame tube into a mixed air portion, which is guided behind a flame zone into the interior of the flame tube, and a burner air portion, which is supplied to a burner arranged on the inlet side of the flame tube for combustion with fuel.wherein the fuel / air ratio is controlled by varying the clear flow width of the mixed air openings by means of a control device.

[0002] GB 1 601 218 A shows a gas turbine combustion chamber system with mixed air openings on a flame tube, which are arranged in an inlet channel and whose flow width can be mechanically controlled by a valve via a pressure difference between the inlet channel and the outside air. For this purpose, the pressure in the supply channel acts via an opening on a piston arranged in a cylinder chamber, and the outside pressure acts via an opening in a valve arrangement. A primary air inlet is controlled by another valve. This combustion chamber system thus includes several coordinated, interacting valves with a relatively large number of individual system components, which entails associated construction and maintenance costs and can cause malfunctions.

[0003] The document DE 19 45 921 A also shows a gas turbine combustion chamber system in which mixed air openings on a flame tube in an air inlet channel are controlled in their flow width depending on a pressure difference between the pressure in the supply channel and the external environment. A jacket-shaped orifice plate is displaceable by an actuator using a spring-loaded piston.

[0004] A gas turbine combustion chamber system and a method for operating a gas turbine combustion chamber system are also described in DE 41 20 831 A1. In this known gas turbine combustion chamber system and method for operating it under different operating conditions, such as the load point of a turbine at partial load to full load, hot gases from combustion are generated from a compressed air stream. To prevent excess air in the flame zone, means are used that respond to a pressure difference between the combustion chamber itself and the compressed air. The means consist, for example, ofin spring components with a check valve and cause a bypass flow of a portion of the compressed air into a mixing zone on the outlet side of the flame zone or combustion zone, whereby the spring element of the means travels a distance depending on the pressure difference, which causes the respective valve to open for a bypass flow of a portion of the compressed air into the mixing zone. The means of the control device, which are constructed from several individual parts and individually assigned to the mixed air openings, for controlling the proportion of mixed air through the mixed air nozzles and thus also the proportion of burner air supplied to the burner, results in a relatively high design effort, particularly in micro gas turbine combustion chamber systems, which also makes it difficult to adjust the fuel / air ratio in the burner or the combustion air ratio (air ratio λ) as reliably as possible for consistently low-emission and efficient combustion.This design also involves a relatively high order picking and maintenance effort and therefore an increased risk of failure.

[0005] A gas turbine combustion chamber system and a method for its operation are also described in DE 43 04 201 A1. A flame tube is concentrically surrounded by an outer shell, forming an annular air duct, and encloses a combustion chamber. Compressed air is supplied via the air duct to a burner extending through the outer shell and the flame tube into the combustion chamber. Mixed air nozzles are arranged on the circumference of the flame tube, connecting the air duct to the combustion chamber in order to introduce secondary air (mixed air) into the hot gas stream in the flame tube through the mixed air nozzles. The mixed air nozzles are individually adjustable to vary the proportion of mixed air, since a previously tested solution with an adjustment ring common to all mixed air openings was considered disadvantageous there. However, the individual control components of the individual mixed air nozzles also result in the aforementioned disadvantages.

[0006] AT 6 537 E shows a displacement of an inner shell in a combustion chamber system, corresponding to the balance between the pneumatic force of a fuel pressure on the left side of a head and a force acting on the right side of the head, on the turbine side, due to pressure built up there. A bellows-like structure is also shown.

[0007] EP 0 088 933 A1 shows a flame tube with an adjustment device in the form of an adjusting ring surrounding the flame tube, by means of which the ratio of primary air flow to secondary air flow can be controlled depending on the load. Control is achieved by changing the flow cross-sections of the primary air openings and the secondary air openings by rotating and / or axially displacing the adjusting ring. The adjusting ring can be rotated by means of a motor, pneumatic, or hydraulic drive.

[0008] JP H05 231645 A shows a three-part combustion chamber with a swirl body and secondary air ports for the addition of secondary combustion air. An additional mixed air port is also provided. The flow cross-sections of the secondary air ports are completely closed at idle and increase with increasing load. The flow cross-section of the mixed air port remains constant across the load range.

[0009] Various other proposed solutions for controlling the burner air supplied to a burner in a gas turbine combustion chamber system are presented in GB 1257610 A, EP 2778531 A1, FR 2133832 A1, GB 2277582 A, US 3952501 A, and DE 19545311 B4. Various actuators, usually controlled by active control, are arranged in the inflow channel of the air mass flow, and adjustment paths, forces, temperatures, or pressures are manipulated. Such actively controlled devices allow for direct adaptation of the system to the specific conditions of each individual gas turbine.A disadvantage, however, is that this is associated with increased commissioning effort and the various components and actuators result in a relatively high maintenance effort and an increased risk of failure, which, particularly in connection with micro gas turbine combustion chamber systems, creates disadvantages in the goal of achieving low-emission, reliable combustion across the entire load range.

[0010] In micro gas turbine combustion chamber systems, the air mass flow through the turbo components varies greatly with the load point of the connected turbine arrangement across its load range or the required electrical power. Likewise, there is a greatly varying demand for fuel power and thus fuel mass flow between minimum and full load. The respective ratio between air mass flow and fuel mass flow is not constant across the load range, but shifts toward larger air mass flows at partial load. State-of-the-art micro gas turbine combustion chambers with fixed geometries are used. This results in an almost constant distribution across the entire load range between the air passed through the burner and the mixed air introduced into the flame tube after the combustion zone.

[0011] Due to this constant air distribution, a shift in the ratio between air and fuel occurs in the reaction space of the combustion chamber, which leads to a significant change in the combustion air ratio λ, as shown in Fig. 5 shown, in which emissions e (ordinate 6) of CO (reference number 60) and NO x (reference number 61) at full load and part load are plotted against the air ratio λ (abscissa 5). Thus, significantly leaner conditions exist in the combustion chamber at part load than at full load. This means that in burners that are optimized for full load with regard to NO x, CO emissions at part load leave the equilibrium path and are determined by non-equilibrium effects due to insufficient residence times at the high air ratios λ. Therefore, CO emissions sometimes increase sharply at part load.

[0012] The same applies to unburned hydrocarbons (UHCs). This effect can be partially compensated for by fuel staging, which enriches a pilot stage at part load. However, this comes at the cost of an increase in NOx emissions at part load. Furthermore, piloting can only compensate for the influence of the air / fuel ratio shift to a limited extent, so in this case, too, a trade-off must always be made between exhaust emissions at full load and at part load.

[0013] During fuel staging, the fuel mass flow to be introduced is distributed unevenly across different burner stages, resulting in locally richer and thus hotter premixed combustion regions. This stabilizes combustion and simultaneously reduces CO and UHC emissions at load points that are associated with a very lean global condition. This is typically the case at part load. However, the locally higher combustion temperatures simultaneously increase NOx emissions. Furthermore, reducing CO emissions under globally extremely lean conditions, such as those sometimes encountered in micro gas turbines near the minimum load point, is only possible to a very limited extent through fuel staging, so that significant CO and UHC emissions are still emitted at these load points.

[0014] In addition, obstruction of the flow path to the burner leads to an increased pressure loss in the gas turbine combustion chamber system, in particular the micro gas turbine combustion chamber system, whereby the efficiency of the gas turbine, in particular the micro gas turbine, is adversely affected by components of the control device, such as throttles and valve components in the air path.

[0015] Based on these disadvantages of known gas turbine combustion chamber systems with air control devices and taking into account the above preliminary considerations and findings, the object of the invention is to further develop a gas turbine combustion chamber system, in particular a micro gas turbine combustion chamber system, in such a way that low-emission, reliable combustion is achieved over the entire load range of an associated turbine arrangement, and to provide a corresponding method.

[0016] This object is achieved in a gas turbine combustion chamber system having the features of claim 1 and in a method for operating such a system having the features of claim 11.

[0017] In the gas turbine combustion chamber system (hereinafter also referred to as combustion chamber system for short), it is provided according to the invention that the control device has an actuating device which responds to a pressure difference (Δp) between the inflow channel of the air and the environment of the combustion chamber system (usually atmospheric pressure), by means of which the clear flow width (flow cross section) of the mixed air openings can be reduced as a function of the load point, in particular continuously, with increasing load point and increased with decreasing load point.

[0018] In the method for operating a gas turbine combustion chamber system, in connection with the features of the preamble, it is provided that the clear flow width of the mixed air openings is controlled as a function of the pressure difference (Δp) between the inflow channel and the external environment of the combustion chamber system by reducing the clear flow width with an increase in the load point of a coupled turbine arrangement and increasing it with a reduction in the load point.

[0019] With these measures, the pressure difference between the air in the inflow duct or an inflow pipe arranged there and the environment of the combustion chamber system around the pressure casing is advantageously used to regulate the burner air flow and thus the fuel / air ratio during combustion. This allows the air / fuel ratio to be maintained at different load points across the load range of a coupled turbine to achieve optimal exhaust gas values. Optimized control is also facilitated by the moderate temperatures at the installation point in the area of ​​the control device and the pressure difference detection. The pressure gradient between the air in the supply duct and the environment correlates very well with the mass flow behavior required for combustion across the load range of the gas turbine.

[0020] The control device is designed to be mechanical, and in particular passive, with the pressure difference being used indirectly or, preferably, directly as the drive source. This allows the design to be implemented with minimal effort, few components, high reliability, and cost-effectiveness. When the pressure difference is used directly as the drive source, only one pressure-utilizing unit is required, with the mechanism separated from extremely hot components of the flame tube, which contributes to the high reliability. Furthermore, the passively designed control device, particularly for the passively controlled portion of the mixed air flow, advantageously allows for the use of industrially available components. This results in a low risk of failure due to low complexity and low maintenance requirements.The flow channel can also be designed to be as streamlined as possible and as unobstructed as possible in order to keep the pressure loss across the flow path of the air mass flow with the burner air portion small, which has a positive effect on the efficiency of the micro gas turbine combustion chamber in particular.

[0021] The achievement of these advantages is ensured by the fact that, when using the pressure difference (Δp) as an indirect drive source, an actuating unit with a pressure sensor, a converter unit and at least one actuator driven by the latter is present, by means of which the clear flow width of the mixed air openings can be varied via a closing unit, and that, when using the pressure difference (Δp) as a direct drive source, the at least one actuator itself is designed as a pressure sensor, by means of which the clear flow width of the mixed air openings can be varied via the closing unit.When the pressure difference is used indirectly as a drive source, the pressure difference can be indirectly fed via the converter unit to control another mechanical or physical energy source to drive the at least one actuator to change the clear flow width of the mixed air openings via the closing unit, while still utilizing the pressure difference between the inflow channel and the environment. Using the pressure difference as a direct drive source for the actuator results in a particularly simple design.

[0022] According to the invention, the adjusting device has, as at least one adjusting element, a bellows, in particular made of metal, which is firmly connected to the pressure housing with one of its front end regions and is connected to the closing unit comprising at least one closing element with its other front end region, which is spaced apart in the longitudinal direction, at a connecting section via at least one intermediate member, and the interior of the bellows is connected to the air inflow channel via at least one pressure equalization channel. Such a bellows, in particular made of metal, is commercially available in various designs, wherein its deflection for adjusting the closing unit is brought about, on the one hand, by the pressure change as a function of the load point and, on the other hand, counteracting the pressure, by its inherent elastic restoring force. The required effective force parameters can be easily determined, e.g.by simulation and / or real tests, to the respective combustion chamber system, whereby other parameters to be taken into account, such as adjustment range, size and shape of the mixed air openings, can be determined in each case.

[0023] A further advantageous embodiment for simple construction and reliable function consists in the design of the closing unit as an orifice plate which, by means of the actuator, can be moved translationally and / or rotated circumferentially in a manner that more or less closes the mixed air openings to vary the clear flow width or flow cross-section. The mixed air openings can be easily varied depending on the pressure difference using a simple adjustment mechanism via the orifice plate, which is designed, for example, like a sleeve. The material of the closing unit and its physical and mechanical properties can be suitably selected to achieve good functionality, for example with regard to good sliding properties at different flame tube temperatures.

[0024] The fact that the connecting section, the intermediate link and the closing unit are rigidly connected to one another also contributes to an advantageous structure.

[0025] A further advantageous embodiment of the combustion chamber system for the structure and function consists in that the pressure housing has a front wall section on its front side adjacent to the inlet side of the flame tube, on the outer side of which facing the environment of the combustion chamber system a plurality of actuators are mounted, and in that a plurality of intermediate members running along the outer side of the flame tube, in particular through the inflow channel, are designed as holding struts or holding rods, which are connected to the closing unit at their rear end region facing the outlet section of the flame tube and are connected to the actuators assigned to them via the connecting section at their front end region spaced therefrom. The front wall section of the pressure housing is formed, for example, by a burner flange of the installed burner.

[0026] In a further structural embodiment, it is advantageously provided that the closing unit designed as an orifice is designed as an annular orifice which rotates around the flame tube in the area of ​​the mixed air openings and extends axially over the flame tube with a constant internal cross-section adapted to the external cross-section of the flame tube so far that the clear flow width of the mixed air openings can be varied at least largely from completely open to partially (or not completely for functional reasons) closed via the maximum change in the pressure difference (Δp), wherein the flame tube has a constant external cross-section over an axial extension section at least in the area of ​​the mixed air openings and the displacement path of the annular orifice. With these measures, an advantageous coordination of the function with the control orControl of the burner air proportion over the entire load range of the turbine to achieve optimal exhaust gas values.

[0027] Furthermore, the fact that the outer surface of the flame tube, at least over the axial extension section in the area of ​​the mixed air openings and the displacement path, and the inner cross section of the annular orifice have a circular cylindrical shape over its axial extension contributes to reliable functionality, thereby achieving a simple structure and good adjustability.

[0028] If it is further provided that the flame tube has a plurality of mixed air openings in the circumferential direction, preferably equidistantly spaced from one another, for example arranged in the same or in several planes perpendicular to the flame tube axis, and if the annular orifice has a plurality of orifice openings located in the same or in several orifice planes perpendicular to the flame tube axis, which are spaced apart in the circumferential direction corresponding to the mixed air openings and can be brought largely or completely into line with the mixed air openings for the complete or at least largely opening of the mixed air openings at a minimum pressure difference (Δp) and as far as possible out of line with the mixed air openings for the complete or at least largely closing of the mixed air openings at a maximum pressure difference (Δp), then further good coordination options are achieved with regard to precise control of the air mass flow and low-emission combustion, for example.the geometric shape of the mixed air openings and the orifice openings can be selected depending on the combustion requirements at different load points of the turbine, such as size, shape and thus achieved change in the clear flow width for the mixed air portion at the pressure differences present depending on the load point.

[0029] A further advantageous design for a stable structure and reliable function is that the support rods, in their forward section projecting beyond the burner, are guided through holes drilled in the front wall section of the pressure housing into the interior of their assigned bellows and are attached to them via the respective connecting section. The holes can also advantageously serve as connection openings for a pressure equalization connection. Additional pressure equalization holes between the interior of the bellows and the combustion chamber are also conceivable.

[0030] A stable structure, which also promotes reliable function, also consists in the fact that the holding rods are connected to a common circumferential stabilizing ring, which forms a stop against the inside of the front wall section of the pressure housing when the aperture is adjusted towards the minimum flow width or when the mixed air openings are closed.

[0031] The adjustment of the aperture is also facilitated by the fact that the holding rods are guided in the direction of displacement by additional guide elements along the flame tube.

[0032] An advantageous embodiment of the method for function and reliable control is that the control device operates passively, with a control mechanism responding to the pressure difference (Δp) in such a way that an actuator is driven by the pressure difference (Δp) and this drives an orifice plate, by means of which the clear flow width of the mixed air openings is varied as a function of the load point over the load range in order to obtain optimum exhaust gas values.

[0033] The invention will be explained in more detail below using exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 shows a gas turbine combustion chamber system in longitudinal section with a schematically illustrated control device for an air mass flow, Fig. 2 shows essential components of a gas turbine combustion chamber system according to the invention with a flame tube and a control device in a perspective side view, Fig. 3 shows a section of the gas turbine combustion chamber system in a cut-away perspective view, partly from the inside, Fig. 4 shows an enlarged section of the gas turbine combustion chamber system according to Fig. 3 with a section of an adjustment unit in the area of ​​an actuator and Fig. 5 a diagram with a course of emitted pollutant components over the air ratio λ at different load points of a turbine.

[0034] Fig. 1shows a combustion chamber system 1 (partially) in longitudinal section with an outer pressure housing 2, which is provided on the outside, towards the environment, on its front side with a front wall section formed by a burner flange 22, and is surrounded on the circumference by an outer wall 20 (outer shell, preferably a cast body) and on the inside by insulation 21. In the interior of the pressure housing 2, with its outer side spaced from the inside of the insulation 21, a flame tube 34 is arranged, which is provided on its front side (inlet side) with a burner 31 and on its rear side facing away from the front side (outlet side) is connected or can be connected to a turbine arrangement (not shown) via a coupling section with coupling elements designed for this purpose.

[0035] The space between the inside of the pressure housing 2 or the insulation 21 and the outside of the wall of the flame tube 34 is designed as an inflow channel 330 with a circular cross-section, in particular a circular cylindrical, through which compressed air can be supplied from the rear (outlet side) of the combustion chamber system 1 to the burner 31 in order to burn fuel introduced into it in a combustion chamber 30 inside the flame tube 34. In order to achieve the most favorable flow conditions in the inflow channel 330, the latter is provided with an inflow tube 33, between the inside of which and the outside of the flame tube 34 the air is guided to the burner 31, as shown in Fig. 1 show the flow arrows drawn.

[0036] Mixed air openings 320 are arranged in the flame tube 34, preferably in an outlet section located behind the combustion chamber 30 toward the outlet side, in particular behind a flame zone 32 (combustion zone) toward the outlet side. These openings can, for example, be equidistantly spaced from one another in the direction of rotation and, for example, be located in one or more cross-sectional planes perpendicular to the longitudinal extent of the flame tube 34. Air from the compressed air mass flow introduced from the rear of the combustion chamber system 1 can be admixed to the combustion gases flowing from the inlet side to the outlet side inside the flame tube 34 via the mixed air openings 320.

[0037] The proportion of mixed air diverted from the supplied air mass flow can be used to stabilize the combustion processes and optimize the emitted exhaust gas values. The proportion of burner air supplied to the burner is adjusted across the load range of the associated gas turbine as a function of the load point to specify a suitable fuel / air ratio or the combustion air ratio (air ratio λ), as explained in more detail above. For this purpose, the clear flow width through the mixed air openings 320 is varied as a function of the load point of the gas turbine by means of a control device via an actuating device 4 as a function of the pressure difference Δp between the air pressure prevailing in the inflow channel 330 and the air pressure present in the vicinity of the combustion chamber system 1.

[0038] In the present gas turbine combustion chamber system 1, in particular in the form of a micro gas turbine combustion chamber system (such a system is generally designed for burner power ranges from 10 kW to 1.5 MW and occasionally up to 2 MW), the control device has an actuating device 4 with a displaceable closing unit 40, which, as shown in the Fig. 1 to 4 shown, is designed as an annular aperture 400, similar to a cuff, and is provided with aperture openings 401, which are designed in their position and size so that they can be brought into alignment with the mixed air openings 320 as completely as possible, so that their clear flow width is available as completely as possible or at least largely for the passage of the mixed air portion.

[0039] An advantageous further embodiment of the control device with the closing unit 40 and an actuating unit with an actuator responding to the pressure difference Δp between the pressure in the inflow channel 330, in particular in its path for the branched burner air portion, and the ambient pressure on the outside of the pressure housing 2 is shown in the Fig. 2 , 3 and 4 illustrated in more detail using an exemplary embodiment. In the embodiment shown, the mixed air openings 320 are designed as round mixed air bores; however, it is also conceivable to provide mixed air openings 320 with a different geometric shape, such as rectangular or non-symmetrical shapes, in order to suitably vary the clear flow width to achieve an optimal fuel / air ratio or air ratio λ for combustion and optimal exhaust gas values ​​at the respective load point of the gas turbine.

[0040] The baffle is displaced by means of support struts in the form of support rods 41 arranged externally along the flame tube 34 by means of the actuator 43, which responds directly to the pressure difference Δp and is designed in this case as a pressure-utilizing component, in particular a metallic bellows 430. The closing unit thus consists of the displaceable baffle 400, a plurality of support rods 41, and a plurality of metallic bellows 430, wherein the support struts are additionally held in their relative position to one another in their front section facing away from the baffle 400 by a circumferential stabilizing ring 42. The support struts or support rods 41 protrude with their front end portion through through-openings in the front wall portion or the burner flange 22 into the interior of the respectively associated bellows 430, which are aligned and fastened on the outside of the burner flange 22 with their longitudinal axis parallel or concentric to the support rods 41.The support rods 41 are slidably guided in the through-openings and can additionally be guided by additional guide elements on the outside of the flame tube 34. The front ends of the support rods 41 are attached inside the bellows 430 via connecting sections to the front end walls thereof.

[0041] The interior of the bellows 430 is in pressure-equalizing connection with the inflow channel 330 via connecting openings 220 provided in the burner flange 22 or the front wall section of the pressure housing 2, so that the respective (essentially static) pressure correlating with the load point of the gas turbine and the combustion prevails inside the bellows 430, and thus the respective pressure difference Δp dependent on the load point is established, by means of which the bellows 430, which is designed in particular as a metal bellows, is expanded against the spring force caused by its elasticity. As a result, the orifice plate 400 is displaced via the holding rods 41 depending on the pressure difference Δp, and the clear flow width for the mixed air portion through the mixed air openings 320 is adjusted accordingly, so that the fuel / air ratio orthe air ratio λ is adapted to the power requirement of the gas turbine given by the respective load point, whereby the change in the clear flow width of the mixed air openings is adjusted with regard to optimal exhaust gas values ​​and combustion efficiency.

[0042] The bellows 430 are made of high-temperature-resistant stainless steel and are designed to accommodate the pressure differential Δp between the combustion chamber 30 or the inflow channel 330 and the environment across the load range of the gas turbine. Since the pressure level in the combustion chamber is lower at partial load than at full load, the bellows expand further at full load, causing the orifice plate 400 to slide toward the burner 31. This results in the unobstructed area of ​​the mixed air openings 320 being smaller at full load than at part load, and thus a smaller proportion of mixed air being directed through the mixed air openings 320. As a result, the burner air proportion increases at full load, resulting in a higher air ratio λ.Due to the interaction of the expansion of the bellows 430 and the resulting change in the unobstructed area of ​​the mixed air openings 320, an approximately constant air ratio across the burner 31 for the entire load range of the gas turbine can be achieved by designing the control device with its components.

[0043] The stabilizing ring 42, which serves to stabilize the holding rods 41 so that they can move exclusively axially (in the direction of the longitudinal axis of the flame tube 34), also serves in this case to limit the expansion (the adjustment path), so that the bellows 430 cannot expand any further as soon as the stabilizing ring 42 abuts the inside of the burner flange 22.

[0044] The structure shown thus achieves a passively operating, robust control device consisting of a few components, which provides reliable, low-emission control of combustion in gas turbine combustion chamber systems, in particular micro gas turbine combustion chamber systems, over the entire load range.

Claims

1. A gas turbine combustion chamber system (1), in particular micro gas turbine combustion chamber system, comprising: - a combustion chamber (30) which has a longitudinally extending flame tube (34) surrounding a flame zone, which is provided with a burner (31) on its inlet side and is coupled or can be coupled to a turbine arrangement on its outlet side facing away therefrom, and is provided with mixed air openings (320) in an outlet section, - comprising a pressure housing (2) surrounding the combustion chamber (30), between the inner side of which and the outer side of the flame tube (34) for supplying an air mass flow, an inflow channel (330) is formed leading from its outlet side to the inlet side, via which a mixed air portion is guided via the mixed air openings (320) into the interior of the flame tube (34), and a burner air portion is supplied to the burner (31) for combustion with the inflowing fuel, and - comprising a control device via which the burner air portion supplied to the burner (31) can be controlled by varying the mixed air portion depending on the load point of the turbine arrangement by adjusting the clear flow width of the mixed air openings (320), wherein - the control device has an actuating device (4) which responds to a pressure difference (Δp) between the inflow channel (330) of the air and the surroundings of the combustion chamber system (1), by means of which the clear flow width of the mixed air openings (320) is reduced depending on the load point, in particular continuously, with an increasing load point and increased with a decreasing load point, and - the actuating device (4) is mechanically constructed, wherein the pressure difference (Δp) is used indirectly or, in particular, directly as a drive source - when using the pressure difference (Δp) as an indirect drive source, an actuating unit with a pressure sensor, a converter unit and at least one actuator (43) driven by the latter is present, by means of which the clear flow width of the mixed air openings (320) can be varied via a closing unit (40), and when using the pressure difference (Δp) as a direct drive source, the at least one actuator (43) itself is designed as a pressure sensor, by means of which the clear flow width of the mixed air openings (320) can be varied via the closing unit (40); characterized in that - the actuating device (4) has as at least one actuator (43), a bellows (430), in particular made of metal, which is firmly connected with its one end region to the pressure housing (2), and with its other end region spaced apart in the longitudinal direction is connected at a connecting portion via at least one intermediate link to the closing unit (40) comprising at least one closing element, and - the interior of the bellows is connected to the air inflow channel (330) via at least one pressure equalization channel.

2. The combustion chamber system according to claim 1, characterized in that the closing unit (40) is designed as a baffle (400) which is displaceable and / or adjustable in the circumferential direction by means of the actuator (43) in the longitudinal direction of the flame tube (34) that more or less covers the mixed air openings (320) for varying the flow width.

3. The combustion chamber system according to either claim 1 or claim 2, characterized in that the connecting portion, the intermediate link and the closing unit (40) are rigidly connected to one another.

4. The combustion chamber system according to any of the preceding claims, characterized in that the pressure housing (2) has a front wall portion on its front side adjacent to the inlet side of the flame tube (34), on the outer side of which facing the surroundings of the combustion chamber system (1) the actuators (43) are attached, and in that a plurality of intermediate links running along the outer side of the flame tube (34), in particular through the inflow channel (330), are designed as holding rods (41) which are connected to the closing unit (40) at their rear end region facing the outlet section of the flame tube (34) and are connected to the actuators (43) assigned to them via the connecting portion at their front end region spaced apart therefrom.

5. The combustion chamber system according to any of claims 2 to 4, characterized in that the closing unit (40) designed as a baffle (400) is designed as a ring baffle which runs around the flame tube (34) in the region of the mixed air openings (320) and extends axially over the flame tube (34) with a constant inner cross section adapted to the outer cross section of the flame tube (34) so that the clear flow width of the mixed air openings (320) can be varied at least largely from completely open to partially closed via the maximum change in the pressure difference (Δp), wherein the flame tube (34) has a constant outer cross section at least in the region of the mixed air openings (320) and the displacement path of the ring baffle over an axial extension portion.

6. The combustion chamber system according to claim 5, characterized in that the outer surface of the flame tube (34) at least over the axial extension portion in the region of the mixed air openings (320) and the displacement path and the inner cross section of the ring baffle over its axial extension have a circular cylindrical shape.

7. The combustion chamber system according to either claim 5 or claim 6, characterized in that the flame tube (32) has a plurality of mixed air openings (320) in the circumferential direction, preferably equidistantly spaced apart from one another, for example arranged in the same or in a plurality of planes perpendicular to the flame tube axis, and in that the ring baffle has a plurality of baffle openings in the same or in a plurality of baffle planes perpendicular to the flame tube axis, which are spaced apart in the circumferential direction corresponding to the mixed air openings (320) and can be brought largely or completely into alignment with the mixed air openings (320) in order to fully or at least largely open them at a minimum pressure difference (Δp) and out of alignment as far as possible in order to fully or at least largely close the mixed air openings (320) at a maximum pressure difference (Δp).

8. The combustion chamber system according to any of claims 4 to 7, characterized in that the holding rods (41) in their portion projecting forward beyond the burner (31) are guided through bores made in the front wall portion of the pressure housing (2) into the interior of the bellows (430) assigned to them and are fastened to them via the particular connecting portion.

9. The combustion chamber system according to any of claims 4 to 8, characterized in that the holding rods (41) are connected to a common circumferential stabilization ring (42) which forms a stop against the inner side of the front wall portion of the pressure housing (2) upon adjusting the baffle (400) in the direction of the minimum flow width or closing the mixed air openings (320).

10. The combustion chamber system according to any of claims 4 to 9, characterized in that the holding rods (41) are guided in the direction of displacement by additional guide elements along the flame tube (34).

11. A method for operating a gas turbine combustion chamber system (1), in particular a micro gas turbine combustion chamber system, according to one of the preceding claims, in which an air mass flow is supplied via an inflow channel (330) between the inner side of a surrounding pressure housing (2) and the outer side of a flame tube (34) from the outlet side thereof and is divided by means of mixed air openings (320) arranged in an outlet section of the flame tube (31) into a mixed air portion which is guided behind a flame zone into the interior of the flame tube (31), and a burner air portion which is supplied to a burner (31) arranged on the inlet side of the flame tube (34) for combustion with fuel, wherein the fuel / air ratio is regulated by varying the clear flow width of the mixed air openings (320) by means of a control device, wherein the clear flow width of the mixed air openings (320) is regulated depending on the pressure difference (Δp) between the inflow channel (330) and the outer surroundings of the combustion chamber system (1) in that the clear flow width is decreased with an increase in the load point of a coupled turbine arrangement and increased with a reduction in the load point, and wherein the control device operates passively, wherein a control mechanism responds to the pressure difference (Δp) in such a way that an actuator (43) is driven by the pressure difference (Δp), and said actuator moves a baffle (400) by means of which the clear flow width of the mixed air openings (320) is varied depending on the load point over the load range in order to obtain optimal exhaust gas values.