EP3695167B1 - Power station furnace system - Google Patents

Description

The invention relates to a power plant combustion system with a large number of parallel-acting burners arranged in a wall of a combustion chamber and supplied with combustion air via a common windbox, the combustion air being supplied to each individual burner via one or more annular gap (s) concentrically surrounding the burner.

In a power plant combustion system, a large number of burners are usually arranged, acting in parallel, in a wall of a combustion chamber and are supplied with combustion air via a common wind box. The combustion air is preferably supplied to the individual burner via one or more annular gaps concentrically surrounding the burner. The supply of the combustion air to the annular gap comprises means in order to influence the amount of combustion air flowing through the annular gap and subsequently into the combustion chamber. Furthermore, in the annular gap (s), if necessary, air guide devices, such as guide vanes, are arranged in order to introduce the combustion air into the combustion chamber in a spiral as a swirling flow around a flame that forms in front of the burner, with the flow direction of the combustion air flow being changed the position of the guide vanes can be changed. In the case of the arrangement of several concentric annular gaps, both the means for influencing the amount of combustion air flowing through the annular gap and subsequently into the combustion chamber and the air guiding devices, for example guide vanes, can be designed differently and separately controllable in each annular gap. By arranging several concentric annular gaps around a burner, the combustion air for the main and post-combustion can be introduced separately into the combustion chamber in front of a single burner, ie in different combustion zones of the flame in the direction of flow and the amount of combustion air. The guide vanes for generating a swirling flow of the combustion air flow and the means for influencing the amount of combustion air can be integrated as actuators in a control device for controlling the combustion process, so that the combustion process can be controlled separately for each individual burner of a power plant combustion system. For an optimized control of the combustion process in a power plant combustion system, it is necessary to provide each individual burner with an adequate amount of combustion air for the main combustion and the afterburning for optimal combustion of the amount of fuel supplied to the burner to control the fuel-air ratio during combustion, which means that with a known amount of fuel supplied to the burner, the amount of combustion air flowing through each annular gap surrounding the burner must be determined and subsequently changed if necessary.

To influence the amount of combustion air supplied to a burner or a group of burners, it is known to arrange air baffles in the windbox to influence the flow of combustion air within the windbox in order to influence the distribution of the total amount of combustion air supplied to the windbox among individual burners or groups of burners. The total amount of combustion air supplied to the windbox can be determined comparatively easily. However, this solution does not enable optimized control of the combustion process in a power plant combustion system.

To determine the amount of combustion air supplied to a burner, it is known to measure the speed of the flow of combustion air and to calculate the amount of combustion air using the geometric dimensions of the cross-sectional area of the duct carrying the combustion air. To measure the speed of the combustion air flow, dynamic pressure probes which can be introduced into the combustion air flow, also called Pitot tubes or Prandtl's Pitot tubes, are known from the prior art. However, dynamic pressure probes of this type cannot be used for measuring the speed of the combustion air flow in the annular gap of combustion air feeds to a burner in a power plant combustion system, because the flow of the combustion air in the annular gap is extremely turbulent and possibly shows a swirl with strongly curved flow lines, so that a dynamic pressure probe can be used only a directed speed of the combustion air flow can be determined if the combustion air flow hits the probe perpendicularly. In the case of a turbulent flow and the combustion air flow not perpendicularly impinging on the dynamic pressure probe, in particular if the direction of the combustion air flow changes, no directional velocity of the combustion air flow can be determined from the differential pressure determined by the dynamic pressure probe. A determination of the amount of combustion air flowing through an annular gap is therefore not possible by means of dynamic pressure probes arranged in the annular gap. In addition, the combustion air in a coal-fired power plant is heavily loaded with ash particles, which leads to rapid contamination of the pitot tubes. The solution is therefore not applicable for an optimized control of the combustion process in a power plant combustion system.

In the company brochure Measuring individual burner airflow, Application Builletin ICA-06 from Air Monitor Corporation, Santa Rosa, CA 95406, the arrangement of pitot tubes in the direction of flow of the combustion air flow in front of the annular gaps in a wind box that conducts the combustion air to a burner is described. However, as described, pitot tubes are considerably prone to failure due to contamination. Even with an arrangement in a wind box in front of the annular gap, regular, complex maintenance cycles and regular flushing of the pitot tubes with purified fresh air are therefore necessary for reliable function. The arrangement described is therefore mostly only used to calibrate the burner arrangement without a real combustion process taking place. It is also not applicable for an optimized control of the combustion process in a power plant combustion system.

From the DE 200 21 271 U1 a sensor device for determining the one or a group of burners of a burner arrangement with a common combustion air supply via a windbox is known according to the cross-correlation measurement method, in which within the windbox, each spanning the flow cross-section of the windbox, sensor arrangements are arranged so that the each around the a burner or a group of burners supplied combustion air quantity reduced combustion air flow flows through the sensor arrangements. In this case, a sensor arrangement consists of two individual sensor rods or sensor rod groups that span the cross section of the wind box, one behind the other in the direction of flow of the combustion air stream, spaced apart from one another and arranged crossing one another. Correlation methods are used to determine the speed of the combustion air flow from the signals generated on the sensor rods as a result of electrical influence caused by electrically charged particles flying past the sensor rods and transported in the combustion air flow. Based on the speed of the combustion air flow and the associated geometry of the wind box, the amount of combustion air flowing through the wind box can be calculated. The amount of combustion air supplied to an individual burner can, however, only be determined with this device in the case of special arrangements of burners in connection with a specially designed windbox. Such arrangements of burners and designs of a windbox are of little importance in practice. In addition, this solution has the disadvantage that the measurements that refer to one another can have a considerable measurement error due to error propagation. This solution is also for an optimized control of the combustion process in a power plant combustion system is not suitable.

From the DE 10 2012 014 260 A1 a device and a method for controlling the fuel-air ratio during the combustion of ground coal in a coal-fired power plant are known, in which the combustion air quantity measurement and the support air quantity measurement according to the correlation method by evaluating electrical signals that are obtained by means of sensors arranged in the air flow are carried out . For this purpose, two sensor rods are arranged one behind the other in the air flow direction in the air-conducting channel, in which electrical signals are generated by electrical induction, which is caused by electrically charged particles moving past the sensor rods in the air flow, which are fed to a correlation measuring device. The correlation measurement method is used to determine the time that the electrically charged particles need to overcome the distance between the two sensor rods. The flow speed of the air stream is calculated from the time and the distance between the sensor rods and the air volume is calculated based on the geometry of the air-carrying duct. In the direction of air flow in front of the sensor rods, an electrode and a counter-electrode are arranged, which are connected to a high-voltage source with a voltage between 12 kV and 20 kV. The electrode connected to the high voltage source is arranged in the air flow in such a way that at least part of the air flow is exposed to the effect of an ion flow flowing from the electrode to the counter electrode and is thus electrically influenced. For an optimized control of the combustion process of each individual burner arranged in a power plant combustion system, the DE 10 2012 014 260 A1 described device and the described procedure not applicable.
the US 2011/0197831 A1 discloses a power plant combustion system with a plurality of burners arranged in a wall of a combustion chamber. The quantities of fuel and combustion air supplied to the individual burners are measured and regulated individually.

It is common practice to control the combustion process in a power plant generation system using static characteristics, whereby only the amount of fuel supplied to all burners supplied with combustion air via a wind box and the total amount of combustion air supplied to the burners via the wind box are taken into account as control variables. Optimized control of the combustion process is therefore not possible.

The object of the invention is to provide a device for controlling the combustion process in a power plant combustion system, which enables an optimized control of the combustion process, that is to say an optimized control of the combustion process of each individual burner arranged in a power plant combustion system.

According to the invention, this object is achieved by a power plant combustion system with the features of the first patent claim. Claims 2 to 8 describe advantageous embodiments of the invention.

A power plant combustion system with several burners arranged in a wall of a combustion chamber, in which the combustion air is supplied via one or more annular gap (s) concentrically surrounding each burner and each burner has means for influencing the amount of the annular gap (s) in the Having combustion air flowing through the combustion chamber comprises a device for controlling the combustion process which comprises at least means for detecting the amount of fuel supplied to a burner and means for determining the amount of combustion air flowing through the annular gap (s). The device for controlling the combustion process is designed in such a way that control signals are generated for each means for influencing the amount of combustion air flowing through the annular gap (s) surrounding a burner in order to control the amount of combustion air flowing through each annular gap influence. A means for determining the amount of combustion air flowing through an annular gap comprises at least two sensor rods made of electrically conductive material, forming a corresponding pair, which are located in the annular gap transversely to the longitudinal axis of the annular gap or at an angle α to the longitudinal axis of the annular gap with 30 ° ≤ α ≤ 90 ° and in the flow direction of the combustion air flow are arranged one behind the other and parallel at a distance a from one another, the corresponding sensor rods being arranged in such a way that at least some of the combustion air flowing past the first sensor rod of the corresponding pair in the flow direction of the combustion air flow is also the second in the flow direction of the combustion air flow Sensor rod of the corresponding pair flows past. The sensor rods are curved in the longitudinal direction in accordance with the curvature of the annular gap and are arranged to be electrically insulated from the walls forming the annular gap. They are therefore arranged in the annular gap in such a way that their longitudinal direction is almost transversely or at an angle between 30 ° and 90 ° to the direction of flow of the combustion air flow, whereby they are preferably spaced evenly over the length of the sensor rods in the annular gap with a wall that forms the annular gap are arranged. The sensor rods have a length l of l> 20 mm, preferably I> 200 mm, on. A means for determining the amount of combustion air flowing through an annular gap also includes a correlation measuring device to which the sensor rods are electrically connected, whereby by means of the correlation measuring device, by evaluating the electrical influence on the sensor rods caused by the electrically charged particles that are transported past the sensor rods and transported in the combustion air flow is effected, electrical signals generated the speed of the combustion air flow is determined transversely to the longitudinal direction of the sensor rods. In the event that the sensor rods are not arranged transversely to the longitudinal axis of the annular gap, a component of the flow velocity of the combustion air flow in the direction of the longitudinal axis of the annular gap is calculated and based on the component of the flow velocity of the combustion air flow in the direction of the longitudinal axis of the annular gap and based on the geometric Dimensions of the cross-sectional area of the annular gap determines the amount of combustion air flowing through the annular gap. If a burner is surrounded by several annular gaps, as described above, sensor rods are arranged in each annular gap and electrically connected to a correlation measuring device, so that the amount of combustion air flowing through each annular gap surrounding a burner can be determined. Thus, for each burner arranged in the wall of a combustion chamber of a power plant combustion system, an optimal control of the combustion process is possible by adding an adequate amount of combustion air for optimal combustion to the amount of fuel supplied to the burner. The amount of combustion air flowing is determined and is influenced in accordance with the amount of combustion air that is adequate for combustion by means of the means for influencing the amount of combustion air flowing through the annular gap (s) into the combustion chamber.

The component of the flow speed of the combustion air flow in the direction of the longitudinal axis of the annular gap is understood to mean that component of the flow speed of the combustion air flow with which the combustion air flow moves in the direction of the longitudinal axis of the annular gap, i.e. the decisive speed for the transport of a certain amount of combustion air in a specific time unit is through the annular gap. Due to the high degree of turbulence in the flow of the combustion air flow in the annular gap, which in a power plant combustion system has a width between 20 mm and 200 mm and a circumference between 100 cm and 1500 cm, as well as any swirl currents of the combustion air flow in the annular gap, the direction and amount vary widely Components of the flow velocity of the combustion air flow in the annular gap. For the determination of the amount of combustion air supplied to a burner, these various components of the flow velocity of the combustion air flow mentioned above are not relevant. Only the component of the flow velocity of the combustion air flow in the direction of the longitudinal axis of the annular gap is decisive for this, i.e., as described, that component of the flow velocity of the combustion air flow with which the combustion air is transported in the longitudinal direction through the annular gap.

Surprisingly, it has been found that on the sensor rods, which are arranged in an annular gap and form a corresponding pair, as described above, electrical signals are generated by means of the correlation measuring device due to the influence of electrically charged particles flying past the sensor rods and transported in the combustion air flow can be evaluated in such a way that a time offset of the correlating electrical signals is determined, which divided by the distance a between the corresponding sensor rods is a measure of the component of the flow velocity of the combustion air flow in the annular gap transversely to the longitudinal direction of the sensor rods. This is surprising because in real measuring arrangements the distance a between the corresponding sensor rods is 2 - 5 times greater than the width of the annular gap and because the electrically charged particles move in the direction of flow of the combustion air flow, but this movement is due to the high degree of turbulence in the combustion air flow is superimposed by a predominantly chaotic movement of the electrically charged particles in terms of magnitude and direction, frequent collisions with the walls of the annular gap which are at ground potential, which results in an electrical discharge of these particles.

If an air guiding device is arranged to generate a swirling flow of the combustion air stream, it is advantageous to arrange the corresponding sensor rods in the flow direction of the combustion air stream after the air guiding device in the annular gap.

In the case of the arrangement of an air guiding device for generating a swirling flow of the combustion air flow, it is also advantageous to displace the sensor rods forming a corresponding pair in such a way that at least part of the combustion air flowing past the first sensor rod of the corresponding pair in the flow direction of the combustion air flow is also advantageous am in the direction of flow of the combustion air flow second sensor rod of the corresponding pair flows past. The sensor rods should be of sufficient length, i.e. cover approx Combustion air flowing past the sensor rod of the corresponding pair also flows past the second sensor rod of the corresponding pair in the direction of flow of the combustion air flow.

The Sonsor bars are preferably designed as a round bar with a diameter D with 1 mm D 20 mm or as a square bar with an edge length e in the direction of the width b of the annular gap with 1 mm e 20 mm. Real-life conditions are assumed here, i.e. a width b of the annular gap for supplying the combustion air to a burner in a power plant combustion system between 20 mm ≤ b ≤ 200 mm and a circumference of the annular gap between 100 cm ≤ circumference of the annular gap ≤ 1500 cm . On the one hand, the sensor rods must be so stable that they do not vibrate in the combustion air flow, but on the other hand they must not be so large that they excessively narrow the effective cross section of the annular gap for the combustion air flow to pass through.

It can be advantageous to design one or more sensor rods in the longitudinal direction of the sensor rod electrically and possibly also mechanically segmented, the segments forming a sensor rod being arranged in alignment with one another in the longitudinal direction of the segments. The segments of a sensor rod can be connected electrically in series and the electrically segmented sensor rod can be connected, as it were, as an electrical unit to an input of the correlation measuring device. However, each segment of an electrically segmented sensor rod can also be electrically connected to a separate input of the correlation measuring device.

In a further embodiment, the sensor rods can be configured as film strips made of electrically conductive material that are glued onto one of the two walls forming the annular gap, electrically insulated from the wall.

In another preferred embodiment of the means for determining the amount of combustion air flowing through an annular gap, two pairs of corresponding sensor rods are arranged in the annular gap, each with a correlation measuring device electrically connected, the two pairs of corresponding sensor rods being arranged in the longitudinal direction at a different angle α to the longitudinal axis of the annular gap. A pair of corresponding sensor rods is preferably arranged transversely, ie at an angle α ₁ = 90 ° to the longitudinal axis of the annular gap, and the second pair of corresponding sensor rods at an angle of α ₂ = 45 ° to the longitudinal axis of the annular gap, but on the condition that At least part of the combustion air flowing past the first sensor rod of a corresponding pair in the flow direction of the combustion air flow also flows past the second sensor rod of the corresponding pair in the flow direction of the combustion air flow. The speed of the combustion air flow in the direction of the longitudinal axis of the annular gap is determined by evaluating the signals that are generated with the first _{sensor pair, ie at an angle α 1 = 90 ° to the longitudinal axis of the annular gap, while the second, ie in} an angle α ₂ = 45 ° to the longitudinal axis of the annular gap, a pair of sensors arranged a speed _{component of the component of the combustion air flow flowing at an angle α 2} = 45 ° to the longitudinal axis of the annular gap is determined. The swirl angle γ of a combustion air flow with a swirl flow can be calculated from both speeds by means of triangulation if the swirl angle γ fulfills the condition (90 ° - α ₁ )>γ> (90 ° - α ₂ ). The angles α ₁ = 90 ° of one pair of corresponding sensor rods and α ₂ = 45 ° of the second pair of corresponding sensor rods are named as preferred only by way of example. Of course, other angles α ₁ and α _{2 of} the longitudinal directions of the pairs of corresponding sensor rods are also possible if this is necessary to fulfill the condition (90 ° - α ₁ )>γ> (90 ° - α ₂ ). In the event that air guide vanes with adjustable position are arranged in the annular gap, the twist angle can thus be determined and specifically influenced via the position of the air guide vanes, whereby the combustion process can also be influenced, ie controlled.

The particular advantage of the invention is that the speed of the combustion air flow is determined directly in the annular gap (s) surrounding a burner in a power plant combustion system and thus the amount of combustion air supplied to a burner in a power plant combustion system can be determined directly and immediately. By influencing the combustion air flow, ie the amount of combustion air that flows through the annular gap, the combustion process in a power plant combustion system is optimally controlled according to preselected criteria.

Of course, it is also possible in this way to regulate the combustion process in a power plant combustion system.

Fig. 1:

einen Teilschnitt eines Ringspaltes um einen Brenner mit einem korrespondierenden Paar im Ringspalt angeordneter Sensorstäbe, in

Fig. 2a:

einen Längsschnitt durch einen Brenner mit umgebendem Ringspalt und einem im Ringspalt angeordneten korrespondierenden Paar Sensorstäben, in

Fig. 2b und c:

zwei Querschnitte durch einen Brenner mit umgebendem Ringspalt jeweils in der Ebene der angeordneten Sensorstäbe, in

Fig. 3:

einen Teilschnitt eines Ringspaltes um einen Brenner mit einem korrespondierenden Paar im Ringspalt in einem Winkel α = 45° zur Längsachse des Rinspaltes angeordneten Sensorstäben, in

Fig. 4a:

einen Teilschnitt eines Ringspaltes um einen Brenner mit zwei korrespondierenden Paaren im Ringspalt angeordneter Sensorstäbe, wobei die Paare korrespondierender Sensorstäbe jeweils in einem anderen Winkel α zur Längsachse des Rinspaltes angeordnet sind und in

Fig. 4b:

eine Abwicklung des Ringspaltes mit den auf der äußeren Wandung des Brenners angeordneten korrespondierenden Sensorstäben.

The invention will be explained in more detail below on the basis of three exemplary embodiments. The accompanying drawings show in

Fig. 1:

a partial section of an annular gap around a burner with a corresponding pair of sensor rods arranged in the annular gap, in

Fig. 2a:

a longitudinal section through a burner with a surrounding annular gap and a corresponding pair of sensor rods arranged in the annular gap, in

Fig. 2b and c:

two cross-sections through a burner with a surrounding annular gap, each in the plane of the sensor rods, in

Fig. 3:

a partial section of an annular gap around a burner with a corresponding pair of sensor rods arranged in the annular gap at an angle α = 45 ° to the longitudinal axis of the annular gap, in

Fig. 4a:

a partial section of an annular gap around a burner with two corresponding pairs of sensor rods arranged in the annular gap, the pairs of corresponding sensor rods each being arranged at a different angle α to the longitudinal axis of the annular gap and in

Fig. 4b:

a development of the annular gap with the corresponding sensor rods arranged on the outer wall of the burner.

Fig. 1 shows means for determining the amount of combustion air flowing through an annular gap 3 with a burner 1, which is coaxially surrounded by a pipe 2, in such a way that an annular gap 3 is formed between the outer wall of the burner 1 and the pipe 2. The burner 1, the pipeline 2 and the annular gap 3 have a common coaxial longitudinal axis 4. Combustion air is guided in the annular gap 3. The pipeline 2 has an indentation 5 with a reduction in the annular gap width b to increase the flow velocity v of the combustion air flow. In the area of the indentation 5, guide vanes 6 are arranged in the annular gap 3, which cause a swirling flow of the combustion air flow in the annular gap section 3.1 following the indentation in the direction of the coaxial longitudinal axis 4. This annular gap section 3.1 has a constant annular gap width b. The direction of flow of the combustion air flow is illustrated by an arrow 7. The direction of rotation of the swirl flow is illustrated by an arrow 8. The component of the combustion air flow that is decisive for determining the amount of combustion air supplied to burner 1 in the annular gap section 3.1 is the component of the combustion air flow directed parallel to the coaxial longitudinal axis 4 or orthogonally to the cross-sectional area of the annular gap section 3.1. she is in Fig. 1 illustrated by arrow 9. Two sensor rods 10 and 11 are arranged within the annular gap section 3.1. The sensor rods 10 and 11 are each electrically insulated and mounted on the outer wall of the burner 1 by means of two support frames 12. The sensor rods 10 and 11 are arranged transversely to the longitudinal axis 4 and adapted in their longitudinal direction to the curvature of the annular gap section 3.1 in such a way that they are connected to the two walls delimiting the annular gap section 3.1, ie the outer wall of the burner 1 and the inside of the pipeline 2 Length each have the same distance c and d. The distance c is the distance between the outer wall of the burner 1 and the sensor rods 10 and 11 and the distance d is the distance between the inner wall of the pipeline 2 and the sensor rods 10 and 11. The two sensor rods 10 and 11 are to the Annular gap section 3.1 bounding walls equally spaced. They are also arranged in such a way that they are parallel to each other at a distance a, but are rotated radially against each other, in such a way that the second sensor rod 11 in the direction of flow 7 of the combustion air flow in the direction of rotation 8 of the swirl flow of the combustion air flow compared to that in the flow direction 7 of the Combustion air flow first sensor rod 10 is arranged displaced in parallel. the Figures 2a to 2c illustrate the above-described arrangement of the sensor rods 10 and 11 in the annular gap section 3.1. The sensor rods 10 and 11 are electrically connected to a correlation measuring device 13. Electrical signals are generated on the sensor rods 10 and 11 by electrical influence, which is caused by the electrically charged particles flying past the sensor rods 10 and 11 and transported in the combustion air flow, and these signals are evaluated by the correlation measuring device 13 in such a way that a time delay of the correlating electrical signals is determined, which divided by the distance a between the sensor rods 10 and 11 is a measure of the component of the flow velocity v of the combustion air flow in the annular gap section 3.1 transversely to the longitudinal direction of the sensor rods 10 and 11 at the in Fig. 1 The illustrated arrangement of the sensor rods 10 and 11, that is, in the direction of the longitudinal axis 4 of the annular gap section 3.1. Based on the thus determined component of the flow velocity v of the combustion air flow in the direction of the longitudinal axis 4 of the annular gap section 3.1, the amount of combustion air supplied to the burner 1 is determined with the cross-sectional area of the annular gap section 3.1. At the same time, means (not shown) for detecting the amount of fuel fed to a burner 1 are used to measure the amount of fuel fed to burner 1 The amount of fuel is recorded and the combustion process is controlled by changing the amount of combustion air.

The in Fig. 3 The means shown for determining the amount of combustion air flowing through an annular gap 3, the corresponding sensor rods 10 and 11 are arranged at an angle of α = 45 ° to the longitudinal axis 4 of the annular gap. All other features of the annular gap 3 and the arrangement of the sensor rods 10 and 11 in the annular gap section 3.1 correspond to those in FIG Fig. 1 shown means for determining the amount of combustion air flowing through an annular gap 3. With the in Fig. 3 shown means for determining the amount of combustion air flowing through an annular gap 3, as to the Fig. 1 and 2 described, a component of the flow velocity v of the combustion air flow in the annular gap section 3.1, directed at an angle of α = 45 ° to the longitudinal axis 4, is determined by means of the correlation measuring device 13. The component of the flow velocity v of the combustion air flow in the annular gap section 3.1 in the direction of the longitudinal axis 4 of the annular gap section 3.1 is calculated by multiplying the component of the flow velocity v determined with the correlation measuring device 13 by sin α, i.e. sin 45 °. With the thus calculated component of the flow velocity v of the combustion air flow in the annular gap section 3.1 in the direction of the longitudinal axis 4 of the annular gap section 3.1, the amount of combustion air supplied to the burner 1 is then determined with the cross-sectional area of the annular gap section 3.1.

Figure 4a shows an arrangement with two pairs of corresponding sensor rods 10.1 and 11.1 and 10.2 and 11.2. The corresponding sensor rods 10.1 and 11.1 are in their longitudinal direction at an angle α ₁ = 45 ° to the longitudinal axis 4 and the corresponding sensor rods 10.2 and 11.2 in their longitudinal direction at an angle α ₂ = 90 ° to the longitudinal axis 4 of the annular gap section 3.1 on the outer wall of the Burner 1 arranged. The two pairs of corresponding sensor rods 10.1 and 11.1 as well as 10.2 and 11.2. are each electrically connected to a correlation measuring device 13.1 or 13.2. Figure 4b shows a development of this section of the annular gap 3.1 with the two pairs of corresponding sensor rods 10.1 and 11.1 as well as 10.2 and 11.2 arranged on the outer wall of the burner 1. In addition to determining the component of the flow velocity v of the combustion air flow in the direction of the longitudinal axis 4 of the annular gap section 3.1 and then following the calculation of the amount of combustion air supplied to the burner, the swirl angle γ of a swirling air flow with this arrangement can be used can be determined if the twist angle γ _{fulfills the condition (90 ° - α 1} )>γ> (90 ° - α ₂ ). For this purpose, by evaluating the electrical signals generated at the sensor rods 10.1 and 11.1 by means of the correlation measuring device 13.1, the component v _{1 of} the flow velocity v of the combustion air flow and by evaluating the electrical signals generated at the sensor rods 10.2 and 11.2 by means of the correlation measuring device 13.2, the component v _{2 of} the flow velocity v of the combustion air flow is determined.

beschrieben. Die mit den korrespondierenden Sensorstäben 10.2 und 11.2 und der Korrelationsmesseinrichtung 13.2 bestimmte Komponente v₂ der Strömumgsgeschwindigkeit v wird durch die Gleichung $${\mathrm{v}}_2=\cos \mathrm{\gamma }•\mathrm{v}\mathrm{oder}\cos \mathrm{\gamma }={\mathrm{v}}_2/\mathrm{v}$$

beschrieben. Durch Einsetzen von Gleichung (2) in Gleichung (1) erhält man $${\mathrm{v}}_1=\left(\cos 45°+\sin 45°•\sin \mathrm{\gamma }/\cos \mathrm{\gamma }\right)•{\mathrm{v}}_2,$$

durch Umformung von Gleichung (3) erhält man $$\begin{array}{cc}{\mathrm{v}}_1/{\mathrm{v}}_2=\cos 45°+\sin 45°•\tan \mathrm{\gamma }\mathrm{bzw}.& \tan \mathrm{\gamma }=\left({\mathrm{v}}_1/{\mathrm{v}}_2-\cos 45°\right)/\sin 45°.\end{array}$$

Based on Figure 4b the determination of the swirl angle γ of a combustion air flow with a swirl flow is described below by way of example. The angle β enclosed between the flow velocity v and the component v _{1 of} the flow velocity v results from the relationship β = 90 ° - α ₁ - γ or with α ₁ = 45 ° results in β = 45 ° - γ. The angle enclosed between the flow velocity v and the component v _{2 of} the flow velocity v results from the relationship 90 ° - α ₂ + γ or with α ₂ = 90 ° it results that the between the flow velocity v and the component v ₂ of Flow velocity v included angle is equal to the twist angle γ. _{The component v 1 of} the flow velocity v determined with the corresponding sensor rods 10.1 and 11.1 and the correlation measuring device 13.1 is given by the equation $${\mathrm{v}}_{}$$$${\mathrm{}}_1=\cos \left(45°-\mathrm{\gamma }\right)•\mathrm{v}\mathrm{or}{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_1=\left(\cos 45°•\cos \mathrm{\gamma }+\sin 45°•\sin \mathrm{\gamma }\right)•\mathrm{v}$$

described. _{The component v 2 of} the flow velocity v determined with the corresponding sensor rods 10.2 and 11.2 and the correlation measuring device 13.2 is given by the equation $${\mathrm{v}}_{}$$$${\mathrm{}}_2=\cos \mathrm{\gamma }•\mathrm{v}\mathrm{or}\cos \mathrm{\gamma }={\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_2/\mathrm{v}$$

described. Substituting equation (2) into equation (1), one obtains $${\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_1=\left(\cos 45°+\sin 45°•\sin \mathrm{\gamma }/\cos \mathrm{\gamma }\right)•{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_2,$$

by transforming equation (3) one obtains $$\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_1/{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_2=\cos 45°+\sin 45°•\tan \mathrm{\gamma }\mathrm{respectively}.& \tan \mathrm{\gamma }=\left({\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">v</figure-callout>}}_1/{\mathrm{v}}_2-\cos 45°\right)/\sin 45°.\end{array}$$

errechnet werden.The swirl angle can thus be determined from the two specific components v ₁ and v _{2 of} the flow velocity v of the combustion air flow according to the equation $$\mathrm{\gamma }=\mathrm{<figure-callout\; id="1"\; label="arctan\; v"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">arctan</figure-callout>}\left(\left({\mathrm{v}}_{}\right)\right)\left(\left({\mathrm{}}_1/{\mathrm{v}}_2-\cos 45°\right)/\sin 45°\right)$$

can be calculated.

List of the reference symbols used

1

- Brenner

2

- pipeline

3

- Annular gap

3.1

- Annular gap, annular gap section

4th

- longitudinal axis

5

- confiscation

6th

- guide vanes

7th

- Arrow, direction of flow of the combustion air flow

8th

- Arrow, direction of rotation of the swirl flow

9

- Arrow, component of the combustion air flow parallel to the longitudinal axis 4

10

- sensor rod

10.1

- sensor rod

10.2

- sensor rod

11

- sensor rod

11.1

- sensor rod

11.2

- sensor rod

12th

- Trestle

13th

- Correlation measuring device

13.1

- Correlation measuring device

13.2

- Correlation measuring device

Claims (8)

1. Power station furnace system with multiple burners (1) which are arranged in a wall of a combustion chamber and in the case of which the combustion air is supplied via one or more annular gap(s) (3) concentrically surrounding each burner (1) and each burner (1) has means for influencing the quantity of combustion air flowing through the annular gap or gaps (3) into the combustion chamber, with a device for controlling the combustion process, at least comprising means for detecting the quantity of fuel supplied to a burner (1) and means for determining the quantity of combustion air flowing through the annular gap or gaps (3), wherein the device for controlling the combustion process is formed in such a way that actuating signals are generated for each means for influencing the quantity of combustion air flowing through the annular gap(s) (3) surrounding the burner (1) into the combustion chamber, in order in this way to influence the quantity of combustion air flowing through each annular gap (3),
   characterized in that
   means for determining the quantity of combustion air flowing through an annular gap (3, 3.1) at least comprise two sensor rods (10, 11) consisting of electrically conductive material, in the annular gap (3, 3.1) transverse to the longitudinal axis (4) of the annular gap (3, 3.1) or at an angle α with respect to the longitudinal axis (4) of the annular gap (3, 3.1) with 30° ≤ α ≤ 90° and one behind the other in the direction of flow (7) of the combustion air stream and spaced apart in parallel with a spacing a from one another, forming a corresponding pair, and arranged electrically insulated from the walls (1, 2) that form the annular gap (3, 3.1),
   wherein the sensor rods (10, 11) are adapted in their shape to the curvature of the annular gap (3, 3.1) and have a length 1 of 1 > 20 mm, preferably 1 > 200 mm, and wherein the sensor rods (10, 11) are electrically connected to a. correlation measuring device (13), by means of which the flow velocity (v) of the combustion air stream orthogonal to the longitudinal direction of the sensor rods (10, 11) is determined by evaluating the electrical signals generated by the electrical influence on the sensor rods (10, 11) that is brought about by electrically charged particles transported in the combustion air stream and moving past the sensor rods (10, 11), wherein, in the event that the sensor rods (10, 11) are not arranged transversely to the longitudinal axis (4) of the annular gap (3, 3.1), a component (v₂) of the flow velocity (v) of the combustion air stream in the direction of the longitudinal axis (4) of the annular gap (3, 3.1) is calculated and, on the basis of the component (v₂), the flow velocity (v) of the combustion air stream in the direction of the longitudinal axis (4) of the annular gap (3, 3.1) is calculated, and the quantity of combustion air flowing through the annular gap (3, 3.1) is determined on the basis of the geometrical dimensions of the cross-sectional area of the annular gap (3, 3.1).
2. Power station furnace system according to Claim 1,
   characterized in that
   the sensor rods (10, 11) forming a corresponding pair are arranged in the annular gap (3, 3.1) with in each case the same spacing c, d, which is constant over the length of each sensor rod (10, 11), from the two walls (1, 2) forming the annular gap (3, 3.1).
3. Power station furnace system according to Claim 1 or 2,
   characterized in that
   in the case of the arrangement of an air guiding device (6) for generating a swirl flow of the combustion air stream, the sensor rods (10, 11) are arranged in the annular gap (3, 3.1) downstream of the air guiding device (6) in the direction of flow (7) of the combustion air stream.
4. Power station furnace system according to Claim 3,
   characterized in that
   the sensor rods (10, 11) forming a corresponding pair are arranged in parallel but displaced relative to one another, such that at least part of the combustion air flowing past the first sensor rod (10) of the corresponding pair in the direction of flow (7) of the combustion air stream also flows past the second sensor rod (11) of the corresponding pair in the direction of flow (7) of the combustion air stream.
5. Power station furnace system according to Claim 3 or 4,
   characterized in that
   two pairs of corresponding sensor rods (10.1, 11.1 and 10.2, 11.2) are arranged in the annular gap (3, 3.1), wherein the two pairs of corresponding sensor rods (10.1, 11.1 and 10.2, 11.2) are arranged at a different angle α with respect to the longitudinal axis (4) of the annular gap (3, 3.1).
6. Power station furnace system according to one of Claims 1 to 5,
   characterized in that
   the sensor rods (10, 11) are formed as a round rod having a diameter D with 1 mm ≤ D ≤ 20 mm, or as a square rod having an edge length e in the direction of the width b of the annular gap with 1 mm ≤ e ≤ 20 mm.
7. Power station furnace system according to Claims 1 to 5,
   characterized in that
   the sensor rods (10, 11) are formed by foil strips of an electrically conductive material which are adhesively attached to one of the two walls (1, 2) forming the annular gap (3, 3.1) and insulated with respect to the wall (1, 2) within the annular gap (3, 3.1).
8. Power station furnace system according to Claims 1 to 7,
   characterized in that
   the sensor rods (10, 11) are segmented in the longitudinal direction, wherein either the segments of the sensor rods (10, 11) are electrically connected to one another in series and the series connections of the sensor rods (10, 11) are electrically connected to a correlation measuring device (13) or the segments of the sensor rods (10, 11) are electrically connected to a correlation measuring device (13).

Images