In combustion systems it is often desirable to obtain a combustion reaction having selected characteristics. For instance, it can be beneficial for a particular a combustion system to receive uniform heat over a particular volume, or for a portion of the combustion system to receive more heat than other parts of the combustion system—for example to tailor a heat flux profile along the process tubes of certain furnaces. Likewise, it can be beneficial for the combustion reaction to have a particular width, length, or temperature.
One embodiment is a combustion system comprising a burner configured to sustain a combustion reaction. The combustion system includes a camera configured to capture a plurality of images of the combustion reaction. A control circuit is configured to receive the plurality of images from the camera and to produce from the plurality of images an averaged image of the combustion reaction. The control circuit is configured to adjust the combustion reaction based on the averaged image.
In one embodiment the combustion system includes a memory configured to store reference data. The control circuit compares the averaged image to the control data and adjusts the combustion reaction based on the comparison of the averaged image and the reference data.
In one embodiment the reference data includes one or more combustion reaction reference images. Each reference image corresponds to a combustion reaction having particular characteristics. The control circuit is configured to adjust the combustion reaction to conform to a selected one of the reference images.
In one embodiment the combustion system includes one or more field electrodes positioned in or near a combustion reaction region of the combustion system, a counter electrode, and a voltage source configured to apply a voltage between the field electrode and the counter electrode. The control circuit can adjust the combustion reaction by applying or adjusting the voltage between the field electrode and the counter electrode.
In one embodiment the combustion system includes a fuel nozzle configured to output fuel for the combustion reaction. The control circuit can adjust the combustion reaction by adjusting the output of fuel from the fuel nozzle. For example, the control circuit can adjust the combustion reaction by adjusting the velocity of the fuel, the flow rate of the fuel, the concentration of the fuel in a mixture, the direction of the flow of fuel, etc.
In one embodiment the combustion system includes adjustment of a parameter related to the oxygen concentration: airflow velocity, mass or volume flow of air, and other air-related parameters are understood to of necessity relate to the oxygen concentration. The control circuit can adjust the combustion reaction by adjusting the output of air from a variable frequency air fan, louvers on an air register, or other means of air or oxygen control. For example, the control circuit can adjust the combustion reaction by adjusting the velocity of the air, the airflow rate of the fuel, the concentration of the oxygen in a mixture, the direction of the airflow of fuel, etc.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.
The camera 104 captures a plurality of successive images of the combustion reaction 102. Each of the images corresponds the combustion reaction 102 at a particular moment. Because the combustion reaction 102 is constantly moving, each of the images captured by the camera 104 will have the combustion reaction 102 in a different position.
Because of the amount of movement in flame location, it can be very difficult to determine whether or not a particular image corresponds to a selected flame shape or selected flame characteristics. The inventors discovered that, by averaging a number of successive image frames, a truer representation of flame characteristics can be obtained. The averaged image frames can thus be used for feedback control of the combustion system 100.
The camera 104 provides the plurality of images to the control circuit 108. The control circuit 108 produces from the plurality of images an averaged image of the combustion reaction 102. The averaged image provides information about the average position and heat profile of the combustion reaction 102. The averaged image can therefore give an indication of how much heat is applied to various areas of a combustion volume. The control circuit 108 can adjust the combustion reaction 102 based on the averaged image in order to obtain a combustion reaction 102 with selected characteristics.
In one embodiment, the memory 109 stores combustion reaction reference data. These data may also be collected from the as-new or as-desired operating condition to be stored as combustion reaction reference data. After the control circuit 108 has produced the averaged image of the combustion reaction 102, the control circuit 108 can compare the averaged image to the reference data stored in the memory 109. In this way the control circuit 108 can determine if the combustion reaction 102 has characteristics in accordance with characteristics selected by an operator of the combustion system 100 or stored in the memory 109. Based on the comparison between the averaged image and the reference data stored in the memory 109, the control circuit 108 can adjust the combustion reaction 102 to achieve the selected characteristics.
After the control circuit 108 has adjusted the combustion reaction 102, the camera 104 captures another series of images of the combustion reaction 102. The control circuit 108 produces another averaged image of the combustion reaction 102 from the most recent series of images captured by the camera 104. The control circuit 108 compares the new averaged image to the reference data stored in the memory 109. If the comparison indicates that the combustion reaction 102 has characteristics substantially in accordance with the selected characteristics, then the control circuit 108 does not adjust the combustion reaction 102. If the comparison indicates that the combustion reaction 102 still has not achieved the selected characteristics, then the control circuit 108 can further adjust the combustion reaction 102.
In one embodiment, the reference data stored in the memory 109 includes a plurality of reference images of the combustion reaction 102. The control circuit 108 compares the averaged image of the combustion reaction 102 to one or more of the reference images. Based on the comparison of the averaged image to the reference images, the control circuit 108 can adjust the combustion reaction 102.
In one embodiment, the desired characteristics of the combustion reaction 102 correspond to a particular target reference image stored in the memory 109. The control circuit 108 compares the averaged image to the target reference image corresponding to the selected characteristics for the combustion reaction 102. The control circuit 108 then adjusts the combustion reaction 102 based on the comparison between the averaged image and the target reference image in order to conform the combustion reaction 102 to the target reference image.
In one embodiment, the camera 104 is a video camera that records a video of the combustion reaction 102. The control circuit 108 than averages the individual frames of the video to produce the averaged image. The camera 104 can be an infrared camera, a visible light camera, an ultraviolet light camera or any other suitable image capture device that can capture images of a combustion reaction 102.
The control circuit 108 can adjust the combustion reaction 102 in a variety of ways. In one embodiment, the burner 101 includes one or more fuel nozzles that emit gaseous or liquid fuel for the combustion reaction 102, the control circuit 108 can adjust the velocity of the fuel, the flow rate of the fuel, the direction of flow of the fuel, or the concentration of fuel and the mixture in order to obtain a combustion reaction 102 with selected characteristics. The control circuit 108 may also adjust the air or air/fuel ratio or one or more other combustion control parameters. Alternatively, the combustion system 100 can include one or more electrodes positioned in or adjacent to a combustion space of the combustion system 100. A voltage source can output to the electrode a high-voltage, thereby creating an electric field in the vicinity of the electrode that can affect the combustion reaction 102 in the selected manner. For example, the electric field can cause the combustion reaction 102 to expand or contract in length or width, can bend the combustion reaction 102 in a selected direction in order to impart more heat to a particular area of the combustion system 100, or can more fully combust the fuel.
In one embodiment the combustion system 100 includes a display coupled to the control circuit 108. The control circuit displays the averaged image of the combustion reaction 102 on the display. A technician can then manually adjust the combustion reaction 102 by manipulating controls of the combustion system 100. Alternatively, the display can display both the averaged image and the selected reference image.
In
While the averaged image 213 has been described as being produced from three images of the combustion reaction, in practice the averaged image 213 can be produced from dozens or hundreds of images of the combustion reaction 102.
After the averaged image 213 has been produced, the control circuit 108 compares the averaged image 213 to one or more reference images stored in the memory 109. The reference images can correspond to particular target combustion reaction profiles that can be selected for the combustion reaction 102.
Each of the reference images 314a-d corresponds to a possible target shape for the combustion reaction 102. For example, it may be desirable in one circumstance for the combustion reaction 102 to bend to the left or to the right in order to heat a particular portion of the wall 211 of the combustion system 200. Alternatively, it may be desirable in another application for the combustion reaction to extend relatively high in the vertical direction. In another application it may be desirable for the combustion reaction 102 to be contracted vertically and widened laterally as shown in
In one example, an operator of the combustion system 200 selects a profile for a combustion reaction 102 corresponding to the reference image 314d from
In one example, the control circuit causes the voltage source 207 to apply a first voltage to the electrodes 206a, 206b. The control circuit 108 further controls the voltage source 207 to apply a second voltage to the combustion reaction holder 210, which acts as a conductive counter electrode. This generates an electric field in the vicinity of the electrodes 206a, 206b, attracting the combustion reaction toward the electrodes 206a, 206b thereby widening the combustion reaction 102.
In
In
In an alternative example the control circuit 108 can cause the combustion reaction 102 to bend toward the field electrode 206a by applying the first voltage signal to the field electrode 206a while not applying the first voltage signal to the field electrode 206b. Likewise, the control circuit 108 can cause the combustion reaction 102 to bend toward the field electrode 206b by applying the first voltage signal to the field electrode 206b while not applying the first voltage signal to the field electrode 206a.
While the combustion reaction holder 210 has been disclosed as a counter electrode to the field electrodes 206a, 206b, many other structures can be used for a counter electrode to which the second voltage signal is applied. For example, the counter electrode can be a conductive fuel nozzle from which fuel is output for the combustion reaction 102. The counter electrode can also be a conductor placed in the fuel stream output from the fuel nozzle. Alternatively, the counter electrode can be a corona electrode positioned near or in the fuel stream. The counter electrode can also be a grounded surface or body near the combustion reaction 102. Those of skill in the art will understand that many other structures are possible for a counter electrode in view of the present disclosure. Likewise, a field electrode can be positioned differently than shown in the FIGS. For example, a field electrode can be placed above the combustion reaction 102 or in another position different than shown in the FIGS. Those of skill in the art will understand, in light of the present disclosure, that many arrangements are possible for electrodes to affect a combustion reaction.
In one embodiment, an electric field generated by applying the first voltage signal to the field electrodes 206a, 206b is selected to cause in the combustion reaction 102 a reduction in oxides of nitrogen (NOx) with respect to the combustion reaction 102 in an absence of the electric field. Alternatively, or additionally, the electric field is selected to cause in the combustion reaction 102 a reduction in carbon monoxide (CO) with respect to the combustion reaction 102 in an absence of the electric field.
In one embodiment, the first voltage signal is ground. Alternatively, the first and second voltages can be time varying voltages substantially opposite in polarity from each other. The first voltage signal can also comprise a chopped DC waveform or a DC offset waveform. The first voltage signal can also be an AC waveform. In one embodiment the AC waveform corresponds to a waveform stored in the memory 109.
In one embodiment the field electrodes 206a, 206b are metal. Alternatively, the field electrodes 206a, 206b can be metal covered in an insulator such as porcelain. In one embodiment, the voltage difference between the first and second voltage signals is greater than 1,000 V. In an alternative embodiment, the voltage difference between the first and second voltage signals is greater than 40,000 V.
The fuel nozzle 610 outputs a mixture of fuel from the fuel source 616 and oxygen from the oxygen source 614. The oxygen source 614 can be air or another source of oxygen.
The camera 104 catches a plurality of images of the combustion reaction 102. The control circuit makes an averaged image from the plurality of images. The control circuit 108 compares the averaged image to reference data stored in the memory 109.
The control circuit 108 is configured to adjust the combustion reaction 102 by adjusting a parameter of the fuel such as an output velocity of the fuel, an output rate of the fuel, an output direction of the fuel, and a concentration of the fuel in a mixture. Likewise, the control circuit 108 is configured to adjust the combustion reaction 102 by adjusting a parameter of the oxygen such as an output velocity of the oxygen, an output rate of the oxygen, an output direction of the oxygen, and a concentration of the oxygen in a mixture.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
The present application is a U.S. Continuation application which claims priority benefit under 35 U.S.C. §120 (pre-AIA) of co-pending International Patent Application No. PCT/US2014/060534, entitled “FLAME VISUALIZATION CONTROL FOR ELECTRODYNAMIC COMBUSTION CONTROL,” filed Oct. 14, 2014 (docket number 2651-130-04); which application claims priority benefit from U.S. Provisional Patent Application No. 61/890,668, entitled “ELECTRODYNAMIC COMBUSTION CONTROL (ECC) TECHNOLOGY FOR BIOMASS AND COAL SYSTEMS,” filed Oct. 14, 2013 (docket number 2651-201-02), co-pending at the date of filing; each of which, to the extent not inconsistent with the disclosure herein, is incorporated herein by reference.
Number | Date | Country | |
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61890668 | Oct 2013 | US |
Number | Date | Country | |
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Parent | PCT/US2014/060534 | Oct 2014 | US |
Child | 15098657 | US |