Device for controlling the combustion process in a power station furnace system

Abstract

Device for controlling combustion process in power station furnace system, having burners (1) in combustion chamber. The combustion air is supplied via annular gap (3) surrounding burners which may influence quantity of combustion air flowing through the annular gap (3). Quantity of fuel supplied to burner (1) is recorded, and quantity of combustion air flowing through annular gap (3) is determined, for which two formed sensor rods (11, 12), arranged in the annular gap (3.1), successively and in parallel, preferably transversely to the longitudinal axis (4) of the annular gap and in the flow direction (7) of the combustion air flow, the sensor rods (11, 12) allow part of the combustion air to flow past the first sensor rod (12) in the flow direction (7) of the combustion air flow and also flows past the second sensor rod (11) in the flow direction (7) of the combustion air flow.

Claims

1. A device for controlling the combustion process in a power station furnace system, comprising a plurality of burners (1) arranged in a wall of a combustion chamber, with combustion air is being supplied via one or more annular gaps surrounding the burner (1) and with the burner (1) comprising an arrangement for influencing the quantity of combustion air flowing through the annular gaps (3) into the combustion chamber, having at least a detector for detecting the quantity of fuel supplied to a burner (1) and an arrangement for determining the quantity of combustion air fuel flowing through the or the annular gaps (3), wherein the device generates control signals to influence the quantity of combustion air flowing through each annular gap (3), wherein the arrangement for determining the quantity of combustion air flowing through an annular gap (3, 3.1) having at least two sensor rods (10, 11) arranged in the annular gap (3, 3.1) sequentially in the flow direction (7) of the combustion air flow transverse to the longitudinal axis (4) of the annular gap (3, 3.1) or at an angle with respect to the longitudinal axis (4) of the annular gap (3, 3.1) with about 3090 and parallel with a spacing a from each other, forming a corresponding pair, wherein the sensor rods (10, 11) are composed of an electrically conductive material and electrically insulated from the walls (1, 2) that form the annular gap (3, 3.1), wherein the shape of the sensor rods (10, 11) is adapted to the curvature of the annular gap (3, 3.1) and the sensor rods (10, 11) have a length l of l>20 mm, and wherein the sensor rods (10, 11) are electrically connected to a correlation measuring device (13) which is used to determine the flow velocity (v) of the combustion air flow orthogonal to the longitudinal direction of the sensor rods (10, 11) by evaluating the electrical signals generated by the effect of electrically charged particles transported in the combustion air flow sensor rods (10, 11) 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 (v.sub.2) of the flow velocity (v) of the combustion air flow in the direction of the longitudinal axis (4) of the annular gap (3, 3.1) is calculated and, based on the component (v.sub.2), the flow velocity (v) of the combustion air flow 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 based on the geometric dimensions of the cross-sectional area of the annular gap (3, 3.1).

2. The device according to claim 1, wherein the sensor rods (10, 11) forming a corresponding pair are each arranged in the annular gap (3, 3.1) from the two walls (1, 2) forming in the annular gap (3, 3.1) with a respective constant spacing c, d, which is constant over the length of each sensor rod (10, 11).

3. The device according to claims 1, wherein when an air guiding device (6) for generating a swirl flow of the combustion air flow is arranged, the sensor rods (10, 11) are arranged in the annular gap (3, 3.1) in the flow direction (7) of the combustion air flow downstream of the air guiding device (6).

4. The device according to claim 3, wherein the sensor rods (10, 11) forming a corresponding pair are arranged in parallel but displaced relative to one another, such that at least a portion of the combustion air flowing past the first sensor rod (10) of the corresponding pair in the flow direction (7) of the combustion air flow also flows past the second sensor rod (11) of the corresponding pair in the flow direction (7) of the combustion air flow.

5. The device according to claim 3, wherein 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 with respect to the longitudinal axis (4) of the annular gap (3, 3.1).

6. The device according to claims 1, wherein the sensor rods (10, 11) are constructed as one of a round rod having a diameter D with 1 mmD20 mm, or as a square rod having an edge length e in the direction of the width b of the annular gap with 1 mme20 mm.

7. The device according to claims 1, wherein sensor rods (10, 11) are formed by foil strips made of an electrically conductive material which are glued onto one of the two walls (1, 2) forming the annular gap (3, 3.1) and insulated with respect to the wall (1, 2).

8. The device according to claims 1, wherein characterized in that the sensor rods (10, 11) are segmented in the longitudinal direction, wherein the segments of the sensor rods (10, 11) are one of 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).

9. The device according to claim 1, wherein the length I of the sensor rods (10, 11) is greater than 200 mm.

Description

[0023] The appended drawings show in:

[0024] FIG. 1 a partial section of an annular gap surrounding a burner with a corresponding pair of sensor rods arranged in the annular gap,

[0025] 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,

[0026] FIGS. 2b and c two cross sections through a burner with a surrounding annular gap, each in the plane of the arranged sensor rods,

[0027] FIG. 3 a partial section of an annular gap surrounding a burner with a corresponding pair of sensor rods arranged in the annular gap at an angle =45 with respect to the longitudinal axis of the annular gap,

[0028] FIG. 4a a partial section of an annular gap surrounding a burner with two corresponding pairs of sensor rods arranged in the annular gap, wherein the pairs of corresponding sensor rods are in each case arranged at a different angle with respect to the longitudinal axis of the annular gap, and

[0029] FIG. 4b a flat pattern of the annular gap with the corresponding sensor rods arranged on the outer wall of the burner.

[0030] FIG. 1 shows means for determining the quantity 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 pipe 2 and the annular gap 3 have a common coaxial longitudinal axis 4. Combustion air is guided in the annular gap 3. The pipe 2 has a constriction 5 with a reduction in the annular gap width b to increase the flow velocity v of the combustion air flow. In the region of the constriction 5, guide vanes 6 are arranged in the annular gap 3, which cause a swirl flow of the combustion air flow in the annular gap section 3.1 downstream of the constriction 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 in the annular gap section 3.1 important for determining the quantity of combustion air supplied to the burner 1 is the component of the combustion air flow directed parallel to the coaxial longitudinal axis 4 or orthogonal to the cross-sectional area of the annular gap section 3.1 and is illustrated in FIG. 1 by the 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 mounted on the outer wall of the burner 1 and electrically insulated by means of two supporting blocks 12. The sensor rods 10 and 11 are arranged transversely to the longitudinal axis 4 and are adapted in their longitudinal direction to the curvature of the annular gap section 3.1 such that they have along their longitudinal extent the same distance c and d to the two walls delimiting the annular gap section 3.1, i.e. the outer wall of the burner 1 and the inside of the pipe 2. 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 pipe 2 and the sensor rods 10 and 11. The two sensor rods 10 and 11 are equally spaced from the walls delimiting the annular gap section 3.1. They are further arranged so as to be mutually parallel with the spacing a, but rotated radially with respect to one another, wherein the second sensor rod 11 in the flow direction 7 of the combustion air flow is arranged with a parallel displacement in the direction of rotation 8 of the swirl flow of the combustion air flow with respect to the first sensor rod 10 in the flow direction 7 of the combustion air flow. FIGS. 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. Due to electrical influence caused by electrically charged particles moving past the sensor rods 10 and 11 and transported in the combustion air flow, electrical signals are generated on the sensor rods 10 and 11, which are evaluated by the correlation measuring device 13 by determining a time offset between the correlating electrical signals, which when divided by the distance a between the sensor rods 10 and 11 is a measure for the component of the flow velocity v of the combustion air flow in the annular gap section 3.1 transverse to the longitudinal direction of the sensor rods 10 and 11 in the arrangement of the sensor rods 10 and 11 shown in FIG. 1, i.e. in the direction of the longitudinal axis 4 of the annular gap section 3.1. Starting from the component of the flow velocity v of the combustion air flow thus determined in the direction of the longitudinal axis 4 of the annular gap section 3.1, the quantity of combustion air supplied to the burner 1 is determined based on the cross-sectional area of the annular gap section 3.1. At the same time, the quantity of fuel supplied to a burner 1 is measured by using unillustrated means configured to detect the quantity of fuel supplied to the burner 1, and the combustion process is controlled by changing the quantity of combustion air.

[0031] In the means shown in FIG. 3 for determining the quantity of combustion air flowing through an annular gap 3, the corresponding sensor rods 10 and 11 are arranged at an angle of =45 with respect 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 of the means shown in FIG. 1 for determining the quantity of combustion air flowing through an annular gap 3. The means shown in FIG. 3 for determining the quantity of combustion air flowing through an annular gap 3, as described with reference to FIGS. 1 and 2, are used to determine with the correlation measuring device 13 a component of the flow velocity v of the combustion air flow in the annular gap section 3.1 directed at an angle of =45 with respect to the longitudinal axis 4. 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 , 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 combustion air quantity supplied to the burner 1 is then determined using the cross-sectional area of the annular gap section 3.1.

[0032] FIG. 4a shows an arrangement with two pairs of corresponding sensor rods 10.1 and 11.1, and 10.2 and 11.2, respectively. The corresponding sensor rods 10.1 and 11.1 are arranged on the outer wall of the burner 1 with their longitudinal direction at an angle .sub.1=45 with respect to the longitudinal axis 4, and the corresponding sensor rods 10.2 and 11.2 are arranged on the outer wall of the burner 1 with their longitudinal direction at an angle .sub.2=90 with respect to the longitudinal axis 4 of the annular gap section 3.1. The two pairs of corresponding sensor rods 10.1 and 11.1, and 10.2 and 11.2, are each electrically connected to a correlation measuring device 13.1 and 13.2, respectively. FIG. 4b shows a flat pattern of this section of the annular gap 3.1 with the two pairs of corresponding sensor rods 10.1 and 11.1, and 10.2 and 11.2, arranged on the outer wall of the burner 1. This arrangement can be used not only for determining the component of the flow velocity of the combustion air flow v in the direction of the longitudinal axis 4 of the ring gap section 3.1 and subsequently the calculation of the quantity of combustion air supplied to the burner, but also for determining the swirl angle of a combustion air flow having a swirl flow when the swirl angle satisfies the condition (.sub.1)>>(.sub.2). To this end, the component v.sub.1 of the flow velocity v of the combustion air flow is determined by evaluating the electrical signals generated on the sensor rods 10.1 and 11.1 using the correlation measuring device 13.1, and the component v.sub.2 of the flow velocity v of the combustion air flow is determined by evaluating the electrical signals generated on the sensor rods 10.2 and 11.2 using the correlation measuring device 13.2.

[0033] An exemplary determination of the swirl angle of a combustion air flow having a swirl flow will be described below with reference to FIG. 4b. The angle enclosed between the flow velocity v and the component v.sub.1 of the flow velocity v results from the relationship .sub.1+, which with .sub.1=45 yields =45. The angle enclosed between the flow velocity v and the component v.sub.2 of the flow velocity v results from the relationship .sub.2+, so that with .sub.2=90 the angle enclosed between the flow velocity v and the component v.sub.2 of the flow velocity v is equal to the swirl angle . The component v.sub.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 described by the equation

v.sub.1=cos(45).Math.v, or v.sub.1=(cos 45.Math.cos +sin 45.Math.sin ).Math.v. (1)

[0034] The component v.sub.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 described by the equation

v.sub.2=cos .Math.v, or cos =v.sub.2/v. (2)

[0035] Substituting equation (2) in equation (1) yields

v,=(cos 45+sin 45.Math.sin /cos ).Math.v.sub.2. (3)

[0036] Transforming equation (3) yields

v.sub.1/v.sub.2=cos 45+sin 45.Math.tan , or tan =(v.sub.1/v.sub.2cos 45)/sin 45.

[0037] The swirl angle may thus be calculated from the two determined components v.sub.1 and v.sub.2 of flow velocity v of the combustion air flow according to the equation =arctan((v.sub.1/v.sub.2cos 45)/sin 45).

LIST OF THE REFERENCE SYMBOLS USED

[0038] 1 burner

[0039] 2 pipe

[0040] 3 annular gap

[0041] 3.1 annular gap, annular gap section

[0042] 4 longitudinal axis

[0043] 5 constriction

[0044] 6 guide vanes

[0045] 7 arrow, flow direction of the combustion air flow

[0046] 8 arrow, direction of rotation of the swirl flow

[0047] 9 arrow, component of the combustion air flow parallel to longitudinal axis 4

[0048] 10 sensor rod

[0049] 10.1 sensor rod

[0050] 10.2 sensor rod

[0051] 11 sensor rod

[0052] 11.1 sensor rod

[0053] 11.2 sensor rod

[0054] 12 supporting block

[0055] 13 correlation measuring device

[0056] 13.1 correlation measuring device

[0057] 13.2 correlation measuring device