Method and Device for Optimizing Combustion in a Power Plant

Abstract

Methods and devices for optimizing combustion of fuel in a combustion chamber of a power plant are provided. A real concentration distribution of a material and/or a real temperature distribution in the combustion chamber is measured in at least one dimension. The real concentration distribution and/or temperature distribution is evaluated and a combustion of fuel is controlled such that a symmetric concentration distribution and/or temperature distribution in the at least one dimension arises. During the evaluation at least one characteristic of the symmetry of the real concentration distribution and/or temperature distribution is determined, and during the controlling at least one control parameter is changed depending on the at least one characteristic.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is the US National Stage of International Application No. PCT/EP2009/067627 filed Dec. 21, 2009, and claims the benefit thereof. The International Application claims the benefits of European Patent Application No. 08172545.9 DE filed Dec. 22, 2008. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

[0002] The invention relates to a method and a device for optimizing the combustion of fuel in a combustion chamber of a power plant, in which a real concentration distribution of a substance and/or a real temperature distribution is measured in the combustion chamber.

BACKGROUND OF INVENTION

[0003] It is the basic object in the case of power plants to monitor the combustion, which occurs in a combustion chamber of the power plant, for example a boiler with a square surface area of 10 meters by 10 meters, over the largest possible area in order to be able to derive therefrom the necessary variables for optimizing the combustion process.

[0004] For example, absorption spectroscopy is a known method. Acoustic pyrometry is a known alternative measurement technique. Absorption spectroscopy and acoustic pyrometry can only measure mean values along a line through the boiler chamber or combustion chamber.

[0005] The CAT (computer-aided tomography) measurement technique is known for calculating the temperature- and concentration distribution in a plane of a combustion chamber from measured mean values at different locations of the combustion chamber of a power plant.

SUMMARY OF INVENTION

[0006] It is an object of the invention to develop a further optimization of the combustion in a power plant.

[0007] The object is achieved by methods and devices as claimed in the independent claims. Advantageous developments are described in the dependent claims.

[0008] The method for optimizing the combustion of fuel in a combustion chamber of a power plant comprises the steps of: measuring a real concentration distribution of a substance in the combustion chamber in at least one dimension, evaluating the real concentration distribution, and controlling the combustion of the fuel such that a symmetric concentration distribution of the substance is created in the at least one dimension.

[0009] Alternatively, or in addition thereto, the method for optimizing the combustion of fuel in a combustion chamber of a power plant comprises the steps of: measuring a real temperature distribution in the combustion chamber in at least one dimension, evaluating the real temperature distribution, and controlling the combustion of the fuel such that a symmetric temperature distribution is created in the at least one dimension.

[0010] More particularly, within the scope of the method, at least one characteristic for the symmetry of the real concentration distribution and/or temperature distribution is established during the evaluation process and at least one control parameter is modified depending on the at least one characteristic during the control process.

[0011] Accordingly, a device for optimizing the combustion of fuel in a combustion chamber of a power plant comprises an apparatus for measuring a real concentration distribution of a substance in the combustion chamber in at least one dimension, an apparatus for evaluating the real concentration distribution, and an apparatus for controlling the combustion of the fuel such that a symmetric concentration distribution of the substance is created in the at least one dimension.

[0012] Alternatively, or in addition thereto, a device for optimizing the combustion of fuel in a combustion chamber of a power plant comprises an apparatus for measuring a real temperature distribution in the combustion chamber in at least one dimension, an apparatus for evaluating the real temperature distribution, and an apparatus for controlling the combustion of the fuel such that a symmetric temperature distribution is created in the at least one dimension.

[0013] In the case of a first advantageous development of the method, two-dimensional concentration distributions and/or temperature distributions are measured during the measurement process and at least one one-dimensional concentration distribution or temperature distribution is calculated therefrom during the evaluation process.

[0014] In the case of a further advantageous development of the method, the real concentration distribution and/or temperature distribution is decomposed into a number of sections during the evaluation process and the combustion is controlled such that a symmetric concentration distribution or temperature distribution is created in each section.

[0015] In other words, an at least one-dimensional, but preferably two-dimensional, distribution of the temperature and/or concentration of at least one substance is generated on the basis of known measurement techniques. The distribution measured thus is used to calculate one-dimensional and mathematical distributions or curves along an axis or along an axis section. Characteristics are preferably established for the distributions, which characteristics ascertain or describe the symmetry or asymmetry (skewness) of the mathematical distribution. Depending on the characteristics, suitable regulating units, such as e.g. metering hoppers for coal or air-control flaps, are trimmed such that there is a symmetric distribution along each axis. If there are a number of mathematical distributions along one axis, the observed axes are subdivided into suitable axis sections and the above-described optimization is then performed for each of the sections.

[0016] The described procedure and the associated device allow a largely homogeneous and hence low-pollutant combustion with automatic adaptation of the regulating parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the following text, an exemplary embodiment is explained in more detail on the basis of the attached schematic drawings, in which:

[0018] FIG. 1 shows an exemplary embodiment of the device,

[0019] FIG. 2 shows an exemplary embodiment of the method, and

[0020] FIG. 3 shows, by means of grayscale values, graphs of the distributions of CO and O₂ in a measurement plane of the device as per FIG. 1 before and after an optimization.

DETAILED DESCRIPTION OF INVENTION

[0021] FIG. 1 illustrates a combustion chamber 10 of a coal power plant (not illustrated in any more detail), in which a coal fire burns during operation of the coal power plant. Here, the combustion chamber 10 contains fuel--coal--together with associated fuel gases, flames 11 and exhaust gases.

[0022] Two measurement planes 12 and 14 are provided in the combustion chamber 10, on the edge of which planes there are measurement instruments 16, which are respectively spaced apart from one another. Two measurement instruments 16 in each case allow a measurement along a line in the associated measurement plane 12 and/or 14, wherein e.g. the concentration of the substances O₂ (oxygen) and CO (carbon monoxide) can be measured with the aid of the measurement instruments 16 and an associated evaluation apparatus 18.

[0023] Furthermore, the measurement instruments 16 and the evaluation apparatus 18 can be used to establish the temperature distribution in the associated measurement plane 12 and/or 14. The measurement in this case is based on a combination of measurement technique and CAT calculation.

[0024] Via a data bus 20, the evaluation apparatus 18 is operationally coupled to an optimization apparatus 22, an operating apparatus 24, and a control apparatus or control and protection system 26. The real concentration distributions and temperature distributions established by the evaluation apparatus 18 are used via the operating apparatus 24 such that the optimization apparatus 22 is used to generate suggestions for optimizing the combustion and these suggestions can be used in the control apparatus 26. This optimizes the flames 11 burning in the combustion chamber 10, in particular in respect of low emission of NO_x(nitrogen oxide).

[0025] For the purposes of optimization, the optimization apparatus 22 evaluates the measured, real concentration distributions and controls the combustion such that a symmetric concentration distribution of the oxygen and carbon monoxide substances is generated along at least one axis or in at least one dimension.

[0026] The associated method is illustrated in FIG. 2. It comprises the step 28 of measuring the concentration distribution of at least the O₂ and CO substances in the aforementioned measurement planes 12 and 14. In step 30, the temperature distribution is established in these planes.

[0027] This input data is used in step 32 to evaluate one-dimensional and mathematical distributions or curves, as well as associated characteristics for the symmetry or asymmetry of the distributions, from the concentration distributions. Furthermore, the distributions or curves are decomposed into a number of sections with their own, associated distributions in step 32.

[0028] Subsequently, on the basis of these investigations, an optimization of the combustion is carried out in step 34 to the effect that symmetric concentration- and temperature distributions are created. These can be monitored in the measurement planes 14 and 16, and so overall this creates a closed-loop control circuit to the step 28.

[0029] Although the measurement as per steps 28 and 30 could evaluate thousands of features or items of information relating to the combustion, it is deliberately only a very small section or part of this information that is processed in the described procedure. Otherwise it would not be possible to achieve an expedient cost/use ratio.

[0030] The evaluation is carried out on the basis of three basic assumptions or three basic simplifications: only direct measurement values, moments, and gradients of the measurements are utilized. Thus, in particular, the distribution tomography of the measured concentrations and temperatures is reconstructed on the basis of, in particular, 20 to 25 points of intersection of the measurements. These direct measurement values are described as feature vectors. Furthermore, the underlying difference values between these direct measurement values are used and, if desired, intermediate values can be established on the basis of interpolation.

[0031] In order to obtain distributions in each desired direction, the first to fourth moment are established along the horizontal, the vertical, and both diagonals of each measurement field, i.e. of each field between the points of intersection. The moments are established on the basis of the profiles or distributions along each measurement direction or dimension. The first and second moment represent the mean value and the variance of a distribution. The third and fourth moment represent the skewness and kurtosis of a distribution. The skewness is a measure of symmetry or lack of symmetry. The kurtosis is a measure of whether the distribution is peaked or shallow compared to a normal distribution or Gaussian distribution.

[0032] Furthermore, the gradient of the mean value is established in each measurement field. The magnitude or value of the gradient provides information (e.g. illustrated as an arrow in the respective measurement field) as to where peaks or concentrations are located in the distribution. FIG. 3 shows the result of the optimization of the combustion undertaken thus. FIG. 3 clearly shows the largely symmetric distribution of CO and O₂ in the measurement plane 12 after the optimization.

Claims

1.-8. (canceled)

9. A method of optimizing combustion of fuel in a combustion chamber of a power plant, comprising: measuring a real concentration distribution of a substance in the combustion chamber in at least one dimension; evaluating the real concentration distribution; controlling a combustion of fuel such that a symmetric concentration distribution of the substance is created in the at least one dimension; determining at least one characteristic for a symmetry of the real concentration distribution during the evaluating; and modifying at least one control parameter depending on the at least one characteristic during the controlling.

10. The method as claimed in claim 9, wherein two-dimensional concentration distributions are measured, and wherein at least one one-dimensional concentration distribution is calculated there from during the evaluating.

11. The method as claimed in claim 9, wherein the real concentration distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric concentration distribution is created in each section.

12. The method as claimed in claim 10, wherein the real concentration distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric concentration distribution is created in each section.

13. A method of optimizing combustion of fuel in a combustion chamber of a power plant, comprising: measuring a real temperature distribution in a combustion chamber in at least one dimension, evaluating the real temperature distribution; controlling a combustion of fuel such that a symmetric temperature distribution is created in the at least one dimension; determining at least one characteristic during the evaluating for a symmetry of the real temperature distribution; and modifying a control parameter during the controlling depending on the at least one characteristic.

14. The method as claimed in claim 13, wherein two-dimensional temperature distributions are measured, and wherein at least one one-dimensional temperature distribution is calculated there from during the evaluating.

15. The method as claimed in claim 13, wherein the real temperature distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric temperature distribution is created in each section.

16. The method as claimed in claim 14, wherein the real temperature distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric temperature distribution is created in each section.

17. A device for optimizing combustion of fuel in a combustion chamber of a power plant, comprising: a measuring device for measuring a real distribution in a combustion chamber in at least one dimension; an evaluation device for evaluating the real distribution; a control device for controlling a combustion of fuel such that a symmetric distribution is created in the at least one dimension.

18. The device as claimed in claim 17, wherein the measuring device measures a real concentration distribution of a substance in the combustion chamber, the evaluation device evaluates the real concentration distribution, and the control device controls the combustion of fuel such that a symmetric concentration distribution of the substance is created in the at least one dimension.

19. The device as claimed in claim 18, wherein two-dimensional concentration distributions are measured, and wherein at least one one-dimensional concentration distribution is calculated there from.

20. The device as claimed in claim 18, wherein the real concentration distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric concentration distribution is created in each section.

21. The device as claimed in claim 17, wherein the measuring devices measures a real temperature distribution in the combustion chamber; the evaluation device evaluates the real temperature distribution; and the control device controls the combustion of the fuel such that a symmetric temperature distribution is created in the at least one dimension.

22. The device as claimed in claim 21, wherein two-dimensional temperature distributions are measured, and wherein at least one one-dimensional temperature distribution is calculated there from.

23. The device as claimed in claim 21, wherein the real temperature distribution is decomposed into a plurality of sections, and wherein the combustion is controlled such that a symmetric temperature distribution is created in each section.

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