Title of Invention

METHOD FOR CONTROLLING A THERMODYNAMIC SYSTEM AND MEASURING DEVICE FOR SAME.

Abstract

A method for controlling a thermodynamic system (1), according to which at least one supply unit (5) supplies with fuel at least two burners (7) assigned to it, and according to which in each existing burner (7) the image of a flame (11) being formed is detected and processed, at least one region of interest of the image of the flame (11) at the root of the flame in the short range field of the burner (7) is selected and its intensity (I) detected as a time-dependent signal and used for controlling.

Full Text

2 The invention relates to a method for controlling a thermodynamic system and a measuring device for controlling a thermodynamic system. In a known method of this type, each supply unit provided feeds the burners assigned to it with an unknown distribution of mass flows and grain spectrums of the coal serving as fuel, the unknown values'making it very difficult to control the process. In each of the burners provided, a measuring device infers, from the presence of a picture of a flame, the presence of a flame. The present invention is based on the object of improving a method of the type mentioned above with respect to the amount of data, and of providing a suitable measuring device. By selecting at least one region of interest of the flame image at the root of the flame in the short range field of the burner and detecting the intensity of said image as a time-dependent signal and using it for controlling, it is possible to capture, with little effort, a small quantity of data characterizing the flame with a sufficient level of approximation, which supplies important information for controlling. It is also possible to monitor more than one region of interest. By reason of the limited quantity of data, fast processing of the same is assured. The invention can be used in different thermodynamic systems, such as power plants, independent of the ftiel and its aggregate state. Therefore, the fuel may be, for example, coal, oil or gas. 3 Preferably, in order to determine the features of the flaine on the basis of the captured time-dependent signal, one calculates a spectrum, for example using a Fast Fourier Transfonnation or other mathematical method with which at least one characteristic value can be obtained, preferably, however, several values, for example five. Using the characteristic value(s), one can achieve, by multiple regression or otlier mathematical method, the best possible approximation of a combination of known fuel particle spcctrums and/or mass flow distributions per burner of each supply unit (for example mill or pump) which need to be polled in advance for initialization; i.e. this way, one can calculate the present fuel particle spectrum and/or the present mass flow distribution. In the case of coal, the fuel pailicle spectrum is a grain spectmm; in the case of oil, a droplet spectnim. In the case of gas, only the mass flow distribution is determined. A suitable measuring device for use in the method according to the invention, obtaining a flame image, has at least one diode detecting exactly one region of interest in the flame image, i.e. focusing exclusively on a fraction of the image. This reduces the data quantity to be detected and processed. In the event of more than one region of interest, a corresponding number of diodes are installed. Preferably, an evaluation unit is assigned to the diode, in particular its proper evaluation unit, determining preferably the spectrum and the characteristic valuc(s). In this case, the data quantity to be transmitted is minimal. However, the main computer can also perform the function of an evaluation unit, although, in this case, a larger data field (compared to the characteristic values) must be transmitted fi-om the measuring unit to the main computer. 4 In order to adjust the diode, i.e. to focus it on the region of interest, a video camera is preferred which is optionally connected to the measuring device. After focusing, the video camera can be disconnected from the measuring device; this will reduce the overall costs in a larger system where there are several measuring devices. For simplified focusing, both the diode and the video camera preferably use the same optical access, for example, a common borescope to which a beam splitter is connected. In addition to a furnace and at least one supply unit, in particular a mill or pump, with at least two assigned burners, a corresponding thermodynamic system controlled by means of the method according to the invention has at least one of the measuring devices according to the invention, preferably, however, one measuring device for each burner. The fuel for a power plant is preferably coal. However, other fuels, in particular solid fuels, can also be used, also as additives. The invention is explained in greater detail below by means of one exemplary embodiment illustrated in the drawing, in which: Fig. 1 is a schematic representation of a power plant. Fig. 2 is a schematic representation of a measuring device, and Fig. 3 is an intensity spectrum in a selected region of a flame. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS A power plant 1, which is an example of a thermodynamic system, has several bunkers 3 containing coarse, medium and fine coal concentrate from which a mill 5 being the supply unit is fed. Generally speaking, fuel other than coal 5 could also be used or added. The coal K coming from the mill 5 is fed, together with the primary air Lp, into a burner 7 in a furnace 9, each mill 5, for cost reasons, feeding several burners 7; in the figure, for example, two units. A flame 11 is then produced at each burner 7 in the furnace 9. Secondary air Ls is blown into the furnace 9 below the burners 7. Each flame 11 is optically captured by a measuring device 15 having a borescope 17 protruding into the furnace 9, reproducing an image of the flame 11 inside the measuring device 15. By means of a beam splitter 19, the image of the flame 11 is optionally directed, on the one hand, to a video camera 21 connected to the measuring device 15 and, on the other hand, to a diode 23 which, using a scanning frequency of, for example, up to 2 kHz- and having, if applicable, an adjusted spectral sensitivity - captures a high time-resolved or, optionally, a high spectral resolved signal. In this case, the borescope 17 is adjusted by means of the video camera 21 in such a way that the diode 23 is focusing on a region of interest (ROI) at the root of the flame in the short range field of the burner 7, the ROI being schematically symbolized by a cross in the figure. Following adjustment, the video camera 21 may be disconnected and used in the adjustment of another measuring device 15. Preferably, the diode 23 sends the signal received to its own evaluation unit 25 that proceeds to an evaluation described below and transmits the result to a computer 31. Said computer 31 serves to control the power plant 1; that is, several control variables, such as the mixture and quality of the coal fed into the mill, which have an impact on the grain spectrum of each burner 7, the quantity of the coal and the quantity of primary air and secondary air, are activated on the basis of the results provided by the measuring devices 15 to reach an optimization 6 goal, for example, minimal nitrogen oxide emission. Since different burners 7 are assigned to each mill 5, not all effective control variables are known. Therefore, in order to calculate the grain spectrum for each burner 7 and the distribution of the coal mass flows to the different burners 7 of a mill 5, the time-dependent signal received is subjected to a Fast Fourier Transformation in the evaluation unit 25 of each diode 23 or, optionally, in the computer 31, thereby obtaining a spectrum of up to 1000 Hz (Sampling Theorem). In the range of approximate 100 to 1000 Hz, the spectrum displays an exponential drop in intensity I and can be sufficiently approximated by five characteristic values. These five characteristic values are the irequency-independent, constant intensity portion Ml corresponding to the intensity I at the frequency f=0; the medium fre-quency value M2 in the range of the intensity drop, i.e. the distance of the range of the intensity drop from the frequency f=0; the position and width M3 of the range of the intensity drop (minimal and maximal values alternatively); the regression coefficient M4, i.e. the gradient in the range of the intensity drop; and scattering M5, i.e. the bandwidth of the intensity in the range of the intensity drop. An initial polling of known grain spectrums and coal mass flow distributions serves to initialize and determine the absolute values. By means of multiple regression or other approximation method using the aforementioned five values over time from all burners 7, one can achieve an optimal approximation of a combination of the known grain spectrums and known coal mass flows from which the variables desired for controlling are calculated. 7 WE CLAIM; 1. Method for controlling a thermodynamic system (1), wherein at least one supply unit (5) supplies fuel to at least two burners (7) assigned to it, and according to which for each existing burner (7) the image of a flame (11) being formed is detected and processed, wherein at least one region of interest of the image of the flame (11) at the root of the flame in the short range field of the burner (7) is selected and its intensity (I) is detected as a time-dependent signal and used for controlling, wherein a spectrum is determined from the time-dependent signal and at least one characteristic value (Ml, M2, M3, M4, M5) is determined from the spectrum providing an intensity drop, characterized in that five characteristic values (Ml, M2, M3, M4, M5) are determined, which are the frequency-independent constant intensity portion (Ml) (= intensity I at the frequency f=0), the medium frequency value (M2) in the range of the intensity drop (= the distance of the range of the intensity drop from the frequency f=0), the position and width (M3) of the range of the intensity drop or its minimal and maximal values, the regression coefficient (M4) (= the gradient in the range of the intensity drop), and the scattering (M5) (= the bandwidth of the intensity in the range of the intensity drop). 2. Method for controlling a thermodynamic system (1) as claimed in claim 1, characterized in that the grain spectrum and/or the distribution of the mass flows per burner (7) in each supply system (5) is calculated by regression or an other approximation method from the characteristic values (Ml, M2, MB, M4, M5). 8 Measuring device (15) for use in a method as claimed in claim 1 or 2, containing an image of the flame (11), characterized in that there is at least one diode (23) detecting exactly one region of interest in the image of the flame (19). Measuring device as claimed in claim 3, characterized in that an evaluation unit (25) is assigned to each diode (23). Measuring device as claimed in claim 4, characterized in that the evaluation unit (25) calculates the spectrum and the characteristic values (Ml, M2, M3, M4, M5). Measuring device as claimed in any one of Claims 3 to 5, characterized in that, optionally, a video camera (21) can be connected to the measuring device (15), by means of which the diode (23) can be adjusted to the region of interest assigned to it, the video camera (21) being disconnectable from the measuring device (15) after adjustment. Measuring device as claimed in Claim 6, characterized in that both the diode (23) and the video camera (21) use the same optical access (17). A method for controlling a thermodynamic system (1), according to which at least one supply unit (5) supplies with fuel at least two burners (7) assigned to it, and according to which in each existing burner (7) the image of a flame (11) being formed is detected and processed, at least one region of interest of the image of the flame (11) at the root of the flame in the short range field of the burner (7) is selected and its intensity (I) detected as a time-dependent signal and used for controlling.

Documents:

00564-kol-2004-abstract.pdf

00564-kol-2004-claims.pdf

00564-kol-2004-correspondence.pdf

00564-kol-2004-description(complete).pdf

00564-kol-2004-drawings.pdf

00564-kol-2004-form-1.pdf

00564-kol-2004-form-18.pdf

00564-kol-2004-form-2.pdf

00564-kol-2004-form-26.pdf

00564-kol-2004-form-3.pdf

00564-kol-2004-form-5.pdf

00564-kol-2004-letters patent.pdf

00564-kol-2004-priority document others.pdf

00564-kol-2004-priority document.pdf

00564-kol-2004-reply f.e.r.pdf

564-KOL-2004-FORM-27.pdf

564-kol-2004-granted-abstract.pdf

564-kol-2004-granted-claims.pdf

564-kol-2004-granted-description (complete).pdf

564-kol-2004-granted-drawings.pdf

564-kol-2004-granted-form 2.pdf

564-kol-2004-granted-specification.pdf

564-KOL-2004-OTHERS PATENT DOCUMENTS.pdf

564-kol-2004-priority document.pdf

564-kol-2004-translated copy of priority document.pdf