EP3403027B1 - Analysis and regulating method for multi-fuel burners - Google Patents

Description

The invention relates to an evaluation and control method for multi-fuel burners and an evaluation and control arrangement for carrying out the method.

In the cement industry, especially in the field of clinker production, raw materials first have to be thermally converted. The thermal conversion of raw material to clinker takes place with the help of a rotary kiln. The thermal energy at the different points of the cement plant is made available by multi-fuel burners, which make it possible to increase the proportion of alternative fuels (e.g. fluff, plastic chips, tire fluff or animal meal), thereby reducing costs and reducing emissions.

So far, the share of substitute fuels in the total fuel could not be kept stable at high proportions (> 70%), since alternative fuels have properties such as a strongly fluctuating moisture content, which have a major influence on the combustion and the generated fuel gases and the end product. In this manufacturing process, falling, not completely burned fuel ends up directly in the reaction area of the raw materials and thus even has a direct effect on the chemical conversion process and thus on the corresponding end product. For a constant high proportion of alternative fuels, permanent monitoring of the fuel and the process status is necessary. Previously existing measuring systems were only able to record the process status with a time delay, which makes quick intervention in the case of fluctuating fuel properties impossible. For example, changing fuel properties in fuel flight behavior cannot be recognized with cameras in the visually visible wavelength range, as are often used for process monitoring control centers.

Out EP 1 364 164 A1 , which shows the preamble of claim 1, discloses a measuring device for flame observation during a combustion process. The measuring device comprises a recording unit which is optically connected to imaging devices and processes optical measuring signals with the aid of data processing.

The DE 10 2006 060 869 A1 describes a method for regulating the operation of a rotary kiln burner, wherein various state variables of the burner flame are evaluated and the control variables of the burner are set as a function thereof.

In US 2007/264 604 A1 A combustion system is shown which has optical sensors arranged on a burner and a data processing unit connected to the system.

Starting from this prior art, it is the object of the present invention to provide an improved evaluation and control method for multi-fuel burners in order to be able to increase or keep the proportion of alternative fuels high.

This object is achieved by an evaluation and control method with the features of claim 1.

Further developments or preferred embodiments of the evaluation and control method are set out in the subclaims.

A first embodiment of an evaluation and control method according to the invention is carried out with a multi-fuel burner for alternative fuels, which has a measuring and control arrangement which has an infrared camera which is assigned to a burner mouth of the multi-fuel burner. Furthermore, the multi-fuel burner is assigned a data processing unit and a regulation and control unit, which are operatively connected to one another and to the infrared camera.

In a step a), a current firing image in the infrared spectral range is recorded with the infrared camera during a firing process, the firing image showing image data of a recording section which comprises the burner mouth and which contains substitute fuel particles.

In the following step b) the image data of the firing image are sent to the data processing unit and there in step c) with the data processing unit the substitute fuel particles as well as the size and position of a majority or all of the particles are determined from the image data.

Current characteristic firing parameters are then determined in step d) from the data recorded in step c) and these are compared with predetermined target firing parameters.

Furthermore, in step e) if the current characteristic firing parameters deviate from the target firing parameters in the regulating and control unit, the regulating and / or control parameters that correlate with the characteristic firing parameters are adjusted, and the characteristic firing parameters are changed until the current characteristic Firing parameters correspond to the target firing parameters.

Finally, the method can be carried out continuously, for which purpose the aforementioned steps a) to e) are repeated continuously.

Using the method, combustion of substitute fuel can be comprehensively monitored, measured and evaluated and used to evaluate the combustion. The entire period of combustion, i.e. H. from the entry of the fuel into the burner, the exit of the fuel from the burner mouth, its flight behavior up to the combustion of the substitute fuel in the combustion chamber.

A fuel changes from a cold, unignited state to an ignition within the burner and finally, ideally, burns completely. Some fuels do not burn or only partially - this can also be detected with the method according to the invention, so that the burning behavior of substitute fuels can be better understood and the proportion in a burning process can be increased significantly.

“Burning parameters” or also combustion parameters in the sense of the invention are all image-based parameters that can be recorded from the image data or the recording by the infrared camera or determined by the subsequent evaluation. The firing parameters describe the state or can describe the state of the combustion map current and over a certain time. "Regulation and / or control parameters" in the sense of the invention are all known manipulated variables which can serve to set the burner and to have a lasting influence on the combustion process.

The invention relates to an evaluation and control method, which may include a pilot control with regard to the fuel composition.

"Adapting the firing parameters" in the sense of the invention means that the firing parameters can be approximated to target specifications. They therefore form dynamic values that change constantly and ideally approximate target values. The term "current" can always be seen at a specific time and changes or adapts over time. Current values at a first point in time with certain burner settings can easily be different from current values at a second point in time with certain burner settings. The "combustion process" in the sense of the invention is every ignition and combustion process as well as every leakage and flight behavior of substitute fuel. A "burning pattern" in the sense of the invention shows a picture of the entire combustion process - thus fuel supply from the burner mouth, ignition behavior of the fuel and its combustion behavior.

With the evaluation and control method according to the invention, it is possible to monitor a burner almost seamlessly during the burning process by using an infrared camera according to the invention. When using an infrared camera with a special spectral filter, the combustion gases become much more transparent to radiation (quasi almost transparent). This makes it possible to recognize the fuel in the images. When measured in the visual spectral range, the flame would block the view of the alternative fuel. The camera therefore offers an insight into the combustion process by showing the existing combustion gases by means of infrared detection and thus the detection of a part of the particle that is not immediately visible. It can be made possible to understand the change in the fuel properties and to correct them immediately if necessary. It can be regulated or controlled manually, the required evaluation and control parameters in one embodiment being able to be set manually by displaying the camera image in a control center and the determined firing parameters. Alternatively, the control or regulation can also take place automatically, for which purpose the firing parameters by the inventive Procedures can be gradually adapted using the evaluation and control unit.

The resulting parameters or firing parameters determined from an imaging method can be used for regulating or controlling the firing process, as a result of which the burner parameters can be further adapted. The changing fuel properties are shown in the infrared camera recordings, among other things, by intensity differences within the recording, dynamic changes over time and by model deviations. For this purpose, various parameters are used, for example to map the differences in intensity and dynamic changes in the particle positions over time and to perform further calculations. Thus, the invention can provide that for determining or detecting or also segmenting the substitute fuel particles from image data of one or more images, one or more parameters of temperature, intensity, amount of speed, direction of speed and probable position of a particle on the basis of previously known temperature or probability - or speed models is determined and further a speed of the burning process is determined from image data of two or more images. The models used are based on process knowledge that corresponds to a knowledge of combustion processes known to the person skilled in the art and results from the area of application of the combustion.

Different image processing methods can be used. In this case, a method can preferably be used, according to which image preprocessing initially takes place, in which contrast-enhancing image processing methods are initially applied to a single image and a reduction to a region of interest takes place, in which, for example, a majority of the particles are statistically suspected becomes.

So-called segmentation takes place after this image preprocessing. A texture filter is placed over the region of interest, after which a further segmentation according to particles or particle agglomerations can take place. Here there is the possibility that a region is already removed from the segmentation if further properties to be checked, such as e.g. B. size, position, distance to the burner mouth, etc. can be seen. In certain regions, the aforementioned properties can also be checked separately and, if the specifications for the properties are not met the region will be removed from the segmentation. There is also the possibility of temporal filtering of the image data (for example temporal mean value filter) in order to be able to distinguish image areas with fuel more clearly from other image areas. The segmentation of the fuel on the basis of individual images and the segmentation on the basis of the temporal filtering of an image sequence can advantageously be combined, for example with the aid of a maximum a posteriori estimate, in order to achieve an improvement in the segmentation accuracy.

After this segmentation, a parameter extraction can take place. Properties of individual particles can be calculated based on the segmentation in individual images (e.g. size, distance to the next particle, location / position, agglomeration yes / no). On the basis of the segmentation of temporally filtered image data and on the basis of the combination of both segmentations, further parameters can be determined mathematically. A normal distribution (mean and standard deviation) for the presence of fuel can be calculated for each image column. Based on these distributions, the mean flight path of the fuel and the distribution behavior or scattering behavior of the fuel in the flight phase can be calculated.

The invention provides that one or more characteristic combustion parameters such as position, size, distribution, mean flight path, time of combustion, distribution behavior or scattering behavior of the substitute fuel particles in the combustion chamber can be selected. Additional information which can be used for an analysis of the combustion process within the combustion chamber is advantageously determined from the image data.

In a further development, the invention provides that in a step c ') further parameters which supplement the characteristic combustion parameters are determined from the image data, such as, for example, agglomerations of the substitute fuel particles or also a probability of residence of the substitute fuel particles in a burner combustion chamber , Furthermore, a time of combustion of the substitute fuel particles after leaving the burner mouth or an impact position or an impact time of the substitute fuel particles in a solid bed in the burner chamber can be determined. The distribution of the replacement fuel particles during a flight phase of the same can also be determined from the image data. The method can thus serve to monitor a combustion process safely and comprehensively and to obtain a large amount of data about different fuel components and compositions.

Furthermore, for the regulation or control of the burner, at least one regulation and / or control parameter such as primary air quantity, secondary air quantity, proportion of the alternative fuel, angle of a pneumodeflector or swirl of the air (also called “swirl”) can be set. These manipulated variables can preferably influence the firing process; for suitable settings u. a. Empirical values used.

In addition to monitoring and regulating the burning process, the invention can provide that current and stored recorded burning parameters can be compared with predetermined target burning parameters based on the infrared camera recordings and subsequent image processing. The burning behavior can be determined from this and this can be evaluated according to predetermined criteria. There are quality criteria for various materials - for example, the percentage of free lime is one such quality criterion for fired clinker. Furthermore, the temperature in the furnace or in certain areas in the furnace or a desired flight behavior or a time of combustion can be used as a quality criterion and also serve as target parameters. Furthermore, the combustion state can also be taken into account directly if, for. B. should be prevented that substitute fuel ends up in the combustion bed. The target parameters can also be adapted accordingly.

Since the actual combustion behavior is shown solely on the basis of the calculated combustion parameters, the target parameters can only be used to a limited extent for the evaluation. However, if, for example, a deviation from a desired combustion time or a deviation from the desired mean flight curve is to be used for the evaluation, the target parameters can also be included in the evaluation.

One embodiment of the invention provides that an evaluation and subsequent evaluation can be carried out. This information can be used to find out properties of different fuel compositions and to make predictions about their combustion process.

The fuel can advantageously be detected with the aid of the infrared camera recording and properties such as the exit and flight behavior, which is divided into a flight curve, material scatter during the flight and a landing zone, be derived. The time of combustion of the particles can also be determined. A look at the alternative fuel component can be taken and an assessment of the spreading behavior can be made. As a result, the properties of the fuel and the characteristic combustion parameters can be monitored almost in real time and changes can be reacted to at an early stage. Different control strategies can be used to further increase the proportion of alternative fuels. Overall, the invention offers the advantage that, as a result of the monitoring, an overall higher proportion of alternative fuels in the overall fuel can be used for industrial combustion processes without having a negative influence on the overall combustion process and ultimately on the product quality.

The exit and flight behavior of substitute fuels in industrial multi-fuel burners can advantageously be analyzed by the invention on the basis of images from infrared cameras, since this type of evaluation and control arrangement can detect a combustion process state in a timely manner by using the method according to the invention.

Other embodiments, as well as some of the advantages associated with these and other embodiments, will become clearer and better understood from the following detailed description with reference to the accompanying figures. Objects or parts thereof which are essentially the same or similar can be provided with the same reference symbols. The figures are merely a schematic representation of an embodiment of the invention.

Fig. 1

eine schematische Ansicht einer erfindungsgemäßen Überwachungsanordnung,

Fig. 2

eine schematische Seitenansicht eines Aufnahmeabschnitts der Infrarot-Kamera mit detektierten Ersatzbrennstoff-Partikeln,

Fig. 3

eine schematische Ansicht einer Verteilung der Ersatzbrennstoff-Partikel,

Fig. 4a-f

fotografische Ansicht eines Brennermundes mit austretenden ErsatzbrennstoffPartikeln bei unterschiedlichen Brennereinstellungen,

Fig. 5

eine fotografische Ansicht einer bildbearbeiteten Aufnahme,

Fig. 6

eine bearbeitete fotografische Aufnahme mit erfassten Partikeln, und

Fig. 7

einen Graphen mit der Verteilung der Partikel.

Show:

Fig. 1

2 shows a schematic view of a monitoring arrangement according to the invention,

Fig. 2

2 shows a schematic side view of a recording section of the infrared camera with detected replacement fuel particles,

Fig. 3

1 shows a schematic view of a distribution of the substitute fuel particles,

4a-f

photographic view of a burner mouth with escaping substitute fuel particles at different burner settings,

Fig. 5

a photographic view of an image-processed picture,

Fig. 6

a processed photograph with captured particles, and

Fig. 7

a graph with the distribution of the particles.

In Fig. 1 shows the monitoring arrangement 10 a multi-fuel burner 1 with a combustion chamber 2 and a burner mouth 3. The combustion chamber 2 is preceded by an infrared camera 4, which can record a recording section A. The infrared camera 4 is operatively connected to a data processing unit 6 via data lines 9. This has a memory 6a in which the parameters, values and models required for the evaluation and control or regulation are stored. Furthermore, the data processing unit 6 is connected to the control and regulation unit 7. This in turn is operatively connected to the burner 1, so that the regulation and control unit 7 can influence the burning parameters of the burning process by changing or adapting the control and regulation parameters.

In Fig. 2 The recording area A of the infrared camera 4 is shown schematically, a flame 11 extending from the burner mouth 3 into the combustion chamber 2. Substitute fuel particles 5 are present within this flame 11 and are carried out of the burner mouth 3 in a certain trajectory F. After a certain time, which depends on the nature and the material of the substitute fuel used, these particles 5 burn or residues of the substitute fuel fall to the bottom of the combustion chamber 2 and form a solid bed 8.

In Fig. 3 An exemplary distribution of the substitute fuel particles 5 is shown schematically, the particles 5 flying out of the burner mouth 3 into the burner chamber 2 within a jet-shaped trajectory F with a mean trajectory F '. The particles 5 can move alone or also form agglomerations 5 '. Furthermore, form on Burner mouth 3 coal areas K. The multi-fuel burner 1 shown has, for example, two fuel feeds. A feeder for the alternative fuel arranged in the center of the burner mouth. Another fuel supply is located coaxially around the substitute fuel supply arranged in the middle and serves as a supply for the standard fuel coal. Two feeds are necessary because coal and substitute fuels are often burned together. The coal areas K show the areas in which the coal exits the burner and then burns in the furnace. It burns very quickly, so that the area K is laterally in front of the burner mouth compared to the slower-burning substitute fuel. If no coal is burned, e.g. B. if 100% substitute fuel is used, there is no coal area K. Fig. 3 shows a diagram of a combustion with a certain proportion of coal, so that the coal areas K form.

The 4a to 4f show photographic images of an infrared camera 4 for various settings of the burner 1. The flame 11 extends from the burner mouth 3 into the burner chamber 2, in which the particles 5 are located. In the infrared images, the particles 5 are shown in dark, almost black gray; the flame 11 can be seen there in medium gray.

The six individual photographic images of the 4a to 4f represent a sequence of an ongoing burning process, with various pre-settings being made on the burner 1, which lead to the different burning patterns. The settings of burner 1 are the parameters EBS (percentage of substitute fuel in percent), the pressure of the pneumodeflector in mbar and a swirl (also called "swirl"). The swirl or air swirl is unitless and in the following numerical example relates to a setting on the burner 1 and can be between a value 1 and a value 9. These three parameters are briefly summarized in the following table and show how a particle beam can be influenced and focused using its parameter settings. FIG. EBS [%] Pneumatic deflector pressure [mbar] swirl 4a 60 40 2 4b 65 40 4 4c 100 40 4 4d 60 40 8th 4e 65 200 4 4f 100 200 4

Using an imaging method, which is based, among other things, on the evaluation of various variables, such as the temperature, brightness, intensity of the flame 11 and a general distribution of the particles 5 in the infrared range, the size and position and thus the individual particles 5 themselves (which are small) Crosses are shown) are recorded as Fig. 5 shows a photograph of the recording area for an exemplary burner setting. A distribution can be calculated from the position and the size of the particles 5, from which their flight path F and also an average flight path 5 'can be determined. In addition, the maximum exit angle W of the total fuel at the burner mouth 3 (in Fig. 5 can be analyzed by means of two lines W on the left and right of the burner mouth 3). The drawn rectangle denotes a region of interest R, to which the image analysis is limited, in which area the particles 5 are "searched for" and analyzed.

The Fig. 6 shows an already processed image, which makes it possible to take a look at the alternative fuel content (particle 5) and to assess its scattering behavior. Building on this picture, e.g. B. individual particles 5 can be detected. Here, only the area in front of the burner mouth 3, ie in a realistic flight area of the fuel, is considered.

If these particle detections are observed over a longer period of time, a kind of hit list can be created, as in Fig. 7 to see. The particles 5 are determined and their properties, such as size, position and distribution, can be further processed by calculation, as in Fig. 7 shown. The individual particle detections of substitute fuel particles are marked as small crosses. From these detections, a column-wise estimate for the location of the fuel can also be carried out, the mean value (thick crosses in the middle) and the standard deviation (crosses above and below the mean values) being formed for a small number of columns of the particle detections. A normal distribution is derived from this. The Dimensions on the graph axes correspond to those of a so-called region of interest. Fig. 7 shows a section of such a region of interest and the curves (lines G) of selected estimates within the region of interest R determined by means of Gaussian estimation, which correspond to the associated mean values and above and below it the 1σ interval of these estimates of the particle detections. The continuous curves represent estimated normal distributions for the location of particles in the respective column (based on the mean values and standard deviations). With the help of the detections, a flight path estimation can also be carried out in a further step. The trajectory F and the mean trajectory F 'of the particles 5 can therefore be concluded from the graph.

For the camera-based detection of the exit and flight behavior of substitute fuel particles of an industrial multi-fuel burner 1 and its regulation and control, the substitute fuel particles 5 can be detected by means of the infrared camera 4 and with the aid of an imaging method.

On the basis of the calculated image-based parameters of the substitute fuel particles 5, parameters can be determined which are suitable for characterizing the exit flight behavior of the particles 5. These parameters can then easily be input into the control of the multi-fuel burner 1 and implemented by the control and regulation unit 7.

It is particularly advantageous that the imaging method preferably uses camera technology that is sensitive in the infrared spectrum. Infrared technology offers the particular advantage that smoke formation and other image components that are obstructive in the visible spectrum are not recorded, but only the image components that also reflect in the infrared spectrum, such as particles 5 or other solids, and their behavior in combustion chamber 2 can be monitored and evaluated ,

LIST OF REFERENCE NUMBERS

1

Multifuel

2

combustion chamber

3

burner mouth

4

Infrared camera

5

Waste-to-particle

5 '

agglomerations

6

Data processing unit

6a

Storage

7

Regulation and control unit

8th

Solid bed

9

data lines

10

supervision order

11

flame

A

receiving portion

F

trajectory

F '

Medium trajectory

K

coal sector

R

Region of interest

G

Gaussian estimation line

W

exit angle

Claims (6)

1. An analysis and regulating method of a multi-fuel burner for alternative fuels having a measuring and regulating assembly (10), having

   - an infrared camera (4) assigned to a burner mouth (3) of the multi-fuel burner (1),

   - a data processing unit (6),

   - and a regulating and control unit (7),

   wherein the data processing unit (6) is operatively connected to the regulating and control unit (7) and to the infrared camera (4),
   comprising the steps of

   a) capturing a current combustion image in the infrared spectral range during a combustion process by means of the infrared camera (4), wherein the combustion image shows image data of a captured section (A), which comprises the burner mouth (3) and contains substitute fuel particles (5),

   characterised by the further steps of:

   b) sending the image data of the combustion image to the data processing unit (6),

   c) determining the substitute fuel particles (5) from the image data by means of the data processing unit (6), and determining the size and position of at least a plurality of the particles (5),

   d) determining current characteristic combustion parameters from the data determined in step c), and comparing said parameters to specified target combustion parameters,

   e) if the current characteristic combustion parameters deviate from the target combustion parameters, adapting regulating and/or control parameters, which correlate with the characteristic combustion parameters, in the regulating and control unit (7), and thus changing the characteristic combustion parameters, until the current characteristic combustion parameters correspond to the target combustion parameters,

   f) continuously repeating the afore-mentioned steps a) to e).
2. The method according to claim 1,
   wherein, in step c),
   at least one parameter from the group of temperature, intensity, velocity magnitude, velocity direction, and probable position of a particle (5) is determined for determining substitute fuel particles (5) from image data of at least one image, based on known temperature and/or probability and/or velocity models.
3. The method according to claim 1 or 2,
   wherein
   the at least one characteristic combustion parameter is selected from the group of position, size, distribution, average trajectory, combustion time, distribution behaviour and/or scattering behaviour of the substitute fuel particles (5) in the combustion chamber (2).
4. The method according to at least any one of claims 1 to 3,
   comprising the step of
   c') from the image data, further determining

   - agglomerations (5') of the substitute fuel particles (5), and/or

   - a probability of presence of the substitute fuel particles (5) in a combustion chamber (2) of the burner (1), and/or

   - combustion time of the substitute fuel particles (5) after leaving the burner mouth (3), and/or

   - determining a strike position and/or a strike time of the substitute fuel particles (5) in a solid bed (8) in the combustion chamber (2), and/or

   - a distribution of the substitute fuel particles (5) during a flight phase.
5. The method according to at least any one of claims 1 to 4,
   wherein
   at least one regulating and/or control parameter from the group of primary air quantity, secondary air quantity, pressure of a pneumo-deflector and/or twisting of the air can be set in step e) for a regulation and/or control at the burner (1).
6. The method according to at least any one of claims 1 to 5,
   comprising the step of
   e') comparing current and stored specific combustion parameters to predetermined target combustion parameters, determining therefrom a combustion behaviour, and evaluating the combustion behaviour according to predetermined criteria.

Images