FIELD

The field relates to a camera system for monitoring a combustion process. BACKGROUND

Combustion involves a set of complex exothermic chemical reactions that take place within a very short period of time. The rate at which combustion reactions occur often makes it difficult to effectively monitor and adjust the parameters for controlling a combustion process.

Different types of sensors have been developed for detecting changes in the level or composition of specific products resulting from a combustion process, such as temperature variations and the types of gases produced. However, it is difficult to position such sensors so as to record data from a region where the combustion is actually taking place, since the combustion region is not fixed to any predefined position. This may result in a delay between the time when combustion takes place and the time when the sensors actually detect changes in the combustion process, which makes it difficult to control a combustion process since the data from the sensors may not reflect actual combustion conditions at the time of detection.

Cameras using optical sensors have been used for detecting visual changes that are indicative of changes in a combustion process. Combustion monitoring techniques using optical sensors have mostly focused on flame shape and boundary analysis. There are several problems to using optical sensors for monitoring combustion. Optical sensors and optical components (such as lenses) are delicate pieces of equipment that do not work well under an environment of intense heat and pressure. Accordingly, there is a need for suitable cooling mechanisms that minimise damage to the optical sensors and components, and poses minimal interference to the optical characteristics of the sensors and components. Further, unburnt fuel particles often exist inside a combustion chamber (due to incomplete combustion of the fuel). Such particles may settle as dust or slag on an external surface of the camera housing for an optical sensor, which impedes the sensor's ability to detect changes in the combustion process. It is not practical to remove the camera for cleaning on a regular basis as this increases downtime which reduces the overall power production capacity of a boiler. It is therefore desired to address one or more of the above problems, or to at least provide a useful alternative to existing combustion monitoring solutions.

SUMMARY

A described embodiment relates to a furnace camera system, including: one or more image sensors for detecting one or more optical characteristics of a product resulting from a combustion process; and

a burn-resistant body having an inner channel and an outer channel, said inner channel extending through said body between an inlet opening and an outlet opening, said inner channel having one or more optical elements positioned therein for adapting light received through said outlet opening for detection by said image sensors; wherein, said outer channel is adapted for directing a flow of fluid around said inner channel to minimise exposure of said inner channel to excessive heat when said system is in use, and said inner channel is adapted for directing a flow of gas to minimise exposure of said one or more optical elements to excessive heat when said system is in use. BRIEF DESCRIPTION OF THE DRAWINGS

Representative embodiments of the present invention are herein described, by way of example only, with reference to the accompanying drawings, wherein:

Figure 1 is a top view of a representative embodiment of the camera system;

Figure 2 is a sectional view of the system along section A-A of Figure 1 ;

Figure 3 is sectional view of a heat-resistant body along section A-A of Figure 1 ;

Figure 4 is an exploded front perspective view of a flow control fitting;

Figure 5 is an exploded rear perspective view of the flow control fitting in Figure 4;

Figure 6 is rear view of the flow control fitting in Figure 4 when assembled;

Figure 7 is a sectional view of the flow control fitting along section B-B of Fig. 4; Figure 8 is a sectional view of the flow control fitting along section C-C of Fig. 4. DETAILED DESCRIPTION OF THE REPRESENTATIVE EMBODIMENTS

The camera system includes one or more image sensors retained inside a housing. The housing is adapted for use inside a combustion chamber (or furnace), and incorporates cooling means to enable the image sensors (and other electronic and/or optical components located inside the housing) to operate effectively within a suitable temperature range. The image sensors detect images of a combustion process that takes place within the combustion chamber and generates image data representing a sequence of one or more detected images. The image data is transmitted to a control module (e.g. of an external control system) for analysing parameters for controlling the combustion process. In a representative embodiment of the camera system 100, as shown in Figures 1 and 2, the housing of the camera system 100 is made up of a main body 102 that is coupled to an air supply unit 104 and a burn-resistant body 106. The burn-resistant body may be coupled to the main body 102 by one or more fasteners 108. The air supply unit 104 may also be coupled to the main body 102 by one or more fasteners (not shown in the Figures), or by having an end portion shaped for being received into a first opening 1 10a of the main body 102 so as to form a secure engagement that resists detachment of the air supply unit 104 from the main body 102.

The burn-resistant body 106 can be made of any material that is resistant to combustion or melting at high temperatures (e.g. up to 1400° C inside a combustion chamber). For example, the burn-resistant body 106 may be made of steel, or another metal or alloy. The air supply unit 104 may include a fan unit for driving a flow of air into an inner chamber inside of the main body 102, or alternatively, may be a valve for controlling a flow of compressed gas (such as air) into the inner chamber of the main body 102. It should be noted that the length of the burn-resistant body 106 may depend on the cooling characteristics and/or its application. For example, the burn-resistant body 106 may be longer or shorter in order to be located at a desired (or predetermined) position away from an expected flame area within the combustion chamber (or furnace). If the burn-resistant body 106 is intended for use within a higher temperature range (such as for monitoring combustion closer to the flame) then the length of the burn-resistant body 106 (as well as the flow characteristics of the inner and/or outer channels 112 and 1 18) may be adjusted so that the burn-resistant body 106 can provide the desired cooling characteristics. When the air supply unit 104 is activated, the air supply unit 104 directs a flow of gas into the inner chamber of the main body 102 via the first opening 110a. The gas then flows out of the inner chamber via a second opening 110b into an inner channel 112 of the burn- resistant body 106. The flow of gas is released via a first outlet opening 116 of the burn- resistant body.

Figures 3 to 8 are representative examples of different components of the camera system 100. It will be understood that the concepts described in this specification are not limited to the features are shown in the figures of this specification. Figure 3 shows a sectional view of the heat-resistant body 106, according to a representative embodiment, including its internal optical and electronic components. The heat-resistant body 106 has one or more holes 126a and 126b formed through a flanged portion 124 of the heat-resistant body 106. The holes 126a and 126b are shaped for receiving a corresponding fastener 108 for coupling the heat-resistant body 106 to the main body 102.

The heat-resistant body 106 has an inner channel 112 (or passageway) formed through the body 106 for directing a flow of gas between a first inlet opening 114 and a first outlet opening 116. The heat-resistant body 106 has an outer channel 1 18 formed around the inner channel 1 12, the outer channel 118 being shaped for directing a flow of fluid (e.g. water or air) around the inner channel 112 to minimise exposure of the inner channel 112 (and any optical and electronic components located therein) to excessive heat when the camera system 100 is in use. Excessive heat means a temperature beyond or exceeding a normal operating temperature range in which the optical and/or electronic components inside the inner channel 1 12 can function and operate normally (or substantially free of interference, distortion or damage). The normal temperature range may be a predefined range of temperatures between a predetermined upper and lower threshold temperature limits.

The outer channel 1 18 may minimise exposure of the inner channel 112 to excessive heat by directing the flow of fluid in a manner so as to be able to substantially maintain or reduce the temperature inside the inner channel 1 12 to a level below a maximum temperature threshold level (or heat level) that substantially impedes the operation of any part, mechanism or component located inside of the inner channel 112. Similarly, the inner channel 1 12 may minimise exposure of the optical components inside the of the 112 to excessive heat by directing the flow of gas in a manner so as to be able to substantially maintain or reduce the temperature inside the inner channel 112 to a level below a maximum temperature threshold level (or heat level) that substantially impedes the operation of any part, mechanism or component located inside of the inner channel 112.

In the representative embodiment shown in Figure 3, the outer channel 1 18 is formed as two concentric channel portions. The outer channel 118 may be formed to direct a flow of fluid around the inner channel 112 in other ways, for example, by defining and directing the fluid to flow along a substantially spiral, circular, circumferential or helical shaped path around the inner channel 1 12. A flow of fluid (e.g. cool water) is fed into an outer channel portion via an inlet port 120 located at a rear end portion of the heat-resistant body 106. The outer channel portion then directs the flow of fluid into an inner channel portion, and the fluid flows out of the inner channel portion via an outlet port 122. In this way, the fluid directed to flow around an outer portion of the heat-resistant body 106 substantially shields the inner channel 112 from heat produced external to the camera system 100. The fluid may absorb some of the heat as it flows through the outer channel portion of the outer channel 1 18. The heated fluid is directed to flow out of the outlet port 122 for cooling, after which it may be redirected into the inlet port for reuse.

The camera system 100 has one or more image sensors 130 for detecting light received through the outlet opening 1 16. It should be understood that the image sensors 130 may be capable of detecting light in both the visible light spectrum and the infrared light spectrum. When the camera system 100 is in use, light produced by a combustion process is received through the outlet opening 1 16 and detected by the one or more image sensors 130. Each image sensor 130 may include one or more of a solid-state matrix sensor, a charge-coupled device (CCD) sensor, and a complementary metal-oxide-semiconductor (CMOS) active pixel sensor. An image sensor 130 may be part of a video camera. Each image sensor 130 is adapted to generate image data representing a sequence of one or more images of a combustion process (e.g. based on the light received through the outlet opening 16). The image data may be generated under the control of electronic components mounted to a printed circuit board 132 on which the image sensor 130 is also mounted. The image data is then transmitted to a combustion control module (not shown in the Figures) using data transmission means in communication with the image sensor 130. Data transmission means refers to any electronic communications circuitry and components (which may be provided by the circuitry on the printed circuit board 132) that are capable of transmitting image data from an image sensor 130 to the combustion control module (e.g. by transmitting the image data via a wire 134, or by other wireless communications techniques).

The combustion control module analysing the image data to determine one or more predetermine characteristics of a product (e.g. flame shape, flame size, or the presence or absence of a particular type of gas) resulting from a combustion process taking place inside a combustion chamber (or furnace), and generates configuration data for controlling one or more devices, systems or components used for controlling the combustion process being monitored. In a representative embodiment, the combustion control module consists of one or more modules provided by way of computer program code for controlling the operation of one or more data processing components to process the image data as described above. Those skilled in the art will appreciate that the processes performed by the software modules of the combustion control module can also be executed at least in part by dedicated hardware circuits, e.g. Application Specific Integrated Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs). For example, the combustion control module may comprise of electronics in a programmable logic controller (PLC) or an intelligent pre-programmable chip. The combustion control module may operate under the control of one or more software modules or components that direct the combustion control module to perform functions including, for example, high speed (i) image separation, (ii) image storage, (iii) image analysis (e.g. at speeds close to or exceeding 100 images per second), and/or (iv) calculate and control cooling rate of the camera system 100 (and/or other cooling systems) based on the temperature within the combustion chamber that the camera system 100 is exposed to.

In a representative embodiment, the combustion control module resides inside the main body 102. Alternatively, the combustion control module may be part of a dedicated computing device or system (e.g. separate from the camera system 100) for processing the image data received from one or more different camera system 100.

In the representative embodiment shown in Figure 3, a single image sensor 130 is mounted inside the inner channel 112. The image sensor 130 is fitted within a central bore of a support member 136. The support member 136 has one or more flow openings 140a and 140b that enable any gas inside the inner channel 1 12 to flow through the support member 136 and around the image sensor 130. The support ember 136 is securely held in position inside the inner channel 122 by one or more circ clips 138a and 138b. It can be appreciated that the image sensors 130 of the camera system 100 does not always need to be located inside the inner channel 112. For example, the image sensors 130 may instead be positioned inside the main body 102, and the inner channel 1 12 adapted to support one or more optical elements (e.g. lenses) for directing light towards the image sensor 130 inside the main body 102.

The term optical element includes a reference to one or more of the following:

• a lens for directing said light towards an image sensor 130;

• an optical component for changing a direction of light.

• an optical filter for directing only a selected one or more wavelengths of light towards an image sensor 130; and

• an optical filter for reflecting only a selected one or more wavelengths of light away from an image sensor 130, and directing any remaining wavelengths of light towards an image sensor 130.

A flow control fitting 128 is coupled to a front end portion of the heat-resistant body 106 adjacent to the outlet opening 116. In the representative embodiment shown in Figure 3, the flow control fitting 128 has a recessed portion adapted for securely retaining an optical element 146 (e.g. a light wavelength filter) proximate to an optical opening 152. The optical element 146 may be securely coupled in the recessed portion by a circ clip 148. The optical opening 152 may be a bore 412 formed through a central portion of the flow control fitting 128.

The flow control fitting 128 has one or more flow directing channels 150a and 150b adapted for directing a flow of gas in the inner channel 112 towards one or more of the following areas: i) a first region proximate to the outlet opening 116 for protecting the adjacent end portion of the heat-resistant body 106 from exposure to excessive heat and/or solid particles (e.g. ash or soot) resulting from the combustion process being monitored when the camera system 100 is in use. For example, the first region may be an area around position X as shown in Figures 4 and 5); and ii) a second region, located directly in front of the outermost optical element 146 coupled to the flow control fitting 128, for minimising an accumulation of solid particles (e.g. ash or soot) around an outer surface of the outermost optical element 146.

Figures 4 and 5 are respectively front and rear exploded perspective views of a representative embodiment of the flow control fitting 128. The flow control fitting 128 includes an outer member 400, inner core 402, optical element 146 and a circ clip 148. To assemble the flow control fitting 128, the optical element 146 is fitted into a recessed portion of the inner core 402, and is securely retained in that position by a circ clip 148. The assembled inner core 402 is then fitted into a recessed portion of the outer member 400. Figure 6 is a rear view of the flow control fitting 128 in the assembled form. Figure 7 is a sectional view of the flow control fitting 128 along section B-B of Figure 4. Figure 8 is a sectional view of the flow control fitting 128 along section C-C of Figure 4.

The flow control fitting 128 has one or more flow directing members 404 formed on an outward facing surface 406 of the flow control fitting 128 around a peripheral portion of the bore 412 of the inner core 402. The outer surface of the flow directing members 404 are positioned adjacent to an inner flanged portion 408 of the outer member 400 for directing a flow of gas towards the first region (e.g. a region around position X as shown in Figures 4 and 5). The inner flanged portion 408 may form an incline of about 45° relative to the longitudinal axis 410 of the flow control fitting 128.

The flow directing members 404 may be formed in a manner so as to define gaps between different adjacent flow directing members 404. The gaps may be shaped so as to direct a flow of gas from the inner channel 1 12 towards the second region (as described above) in a spiral-shaped (or helically-shaped) path. The second region may be an area just in front of the outward facing surface of the optical element 146 as shown in Figures 4 and 5.

In a particularly preferred embodiment of the present invention (not shown in the drawings), the flow control fitting 128 includes eight flow directing members 404 formed on the outward facing surface 406, around the peripheral portion of the bore 412. The outer surface of each of the flow directing members 404 is positioned adjacent to the inner flanged portion 408 of the outer member 400, for directing a flow of gar towards the first region. The flow directing members 404 are evenly spaced around the peripheral portion of the bore 412, so as to define gaps between adjacent flow directing members 404. The gaps are shaped so as to direct a flow of gas from the inner channel 1 12 towards the second region in a spiral-shaped (or helically-shaped) path.

The camera system 100 may also include a heat sensor (not shown in the Figures) communicating with a heat monitoring module (not shown in the Figures) and a retractable mount (not shown in the Figures) which the camera system 100 is coupled to and which positions the camera system 100 relative to said furnace. When at least a part of the heat- resistant body 106 is inserted into the combustion chamber (or furnace), and the heat sensor detects heat in an area proximate to the outlet opening 1 16 exceeding a predetermined threshold heat value, the heat monitoring module controls the mount to retract the heat-resistant body 106 away from (e.g. outside of) the combustion chamber or furnace.

Another aspect of the camera system 100 is that the one or more optical components 146 may be adapted for directing light received from an outlet opening 116 towards an image sensor 130 that is not in collinear alignment with the outlet opening 1 16. For example, in a representative embodiment, the outlet opening 1 16 may allow light to enter the inner channel 1 12 along a first linear axis that is perpendicular or at another angle relative to a second linear axis along which light travels towards an image sensor 130, and the camera system 100 may include one or more of the optical components 146 (e.g. by way of a forming a optical prism) for adapting, bending and/or directing light travelling along the first linear axis onto the second linear axis so that the image sensor 130 is still able to detect light received via the outlet opening 1 16.

Another aspect of the camera system 100 is that the cleaning of an outer surface of the outermost optical element 146 (e.g. an optical lens) may be achieved by cleaning means. The cleaning means may be provided by way of a nozzle (not shown in the Figures) formed in an outer portion of the flow control fitting 128 that directs a flow of fluid (e.g. water or air), such as at high pressure, towards an outer surface of the outermost optical element 146. In a representative embodiment, position of the nozzle may be adjustable (e.g. under the control of the combustion control system) so as to direct the flow of fluid towards the portion of the outer surface of the outer most optical element 146 that requires cleaning. It will be understood that the cleaning means can be provided in other alternative ways, such as by way of a heat (or burn) resistant mechanical wiper that moves to and fro over an outer surface, or by providing a flow of fluid over the outer surface of the outermost optical element 146, or a combination of one or more of the above described cleaning options. The cleaning means may operate under the control of the combustion monitoring system (or another system) that checks the clarity and/or sharpness of the images being detected by the image sensors 130 and controls the cleaning actions to be performed (such as the positioning of the nozzle, direction of the flow of fluid and/or activation of the cleaning means when cleaning is required).

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention. The word 'comprising' and forms of the word 'comprising' as used in this description and in the claims does not limit the invention claimed to exclude any variants or additions.

In this specification, including the background section, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or known to be relevant to an attempt to solve any problem with which this specification is concerned.