SYSTEM AND METHOD FOR MONITORING AND CONTROLLING FURNACES

Abstract

A furnace monitoring system for monitoring a furnace over a span of time during furnace operation, including a thermal imaging apparatus, the apparatus is disposed outside of the furnace and at a distance from the exterior of the furnace to generate field signals of the furnace; a signal processing unit configured and programmed for receiving the field signals and generating a temperature map of the exterior of the furnace; and a means for displaying the temperature map locally or remotely. Wherein in that the furnace monitoring system is a system for monitoring the furnace over a span of time during furnace operation and in that the generated temperature map is divided into several zones, which correspond to different components of the furnace selected from burner, viewing port for burner observation, charging port, discharging port and flue gas channel.

Claims

1-9. (canceled)

10. A furnace monitoring system for monitoring a furnace over a span of time during furnace operation, the monitoring system comprising: a) a thermal imaging apparatus, said apparatus is disposed outside of the furnace and at a distance from the exterior of the furnace to generate field signals of the furnace; b) a signal processing unit configured and programmed for receiving said field signals and generating a temperature map of the exterior of the furnace; and c) a means for displaying the temperature map locally or remotely, wherein: in that the furnace monitoring system is a system for monitoring the furnace over a span of time during furnace operation and in that the generated temperature map is divided into several zones, which correspond to different components of the furnace selected from burner, viewing port for burner observation, charging port, discharging port and flue gas channel.

11. The furnace monitoring system according to claim 10, comprising an infrared CCD camera disposed at a distance from the exterior of the furnace to generate a temperature map of the exterior of the furnace, wherein the temperature map can be viewed locally or remotely.

12. A furnace controlling system for controlling the operation of the furnace over a span of time, the controlling system comprising a furnace monitoring system according to claim 10, the furnace controlling system further comprising: d) an analyzing unit configured and programmed for producing control signals based on the received field signals or the generated temperature map; and e) a furnace controller configured for receiving said control signals and applying them to control the furnace.

13. A method for controlling the operation of a furnace over a span of time using the furnace controlling system of claim 12, the method comprising: a) producing field signals of the exterior of the furnace over the span of time during furnace operation with the thermal imaging apparatus; b) transmitting the field signals to the signal processing unit and generating the temperature map of the exterior of the furnace, which is divided into several zones, which correspond to different components of the furnace selected from burner, charging port, discharging port and flue gas channel, over the span of time, and displaying the temperature map displayed locally or remotely; c) applying, with the analyzing unit, a control algorithm to the received field signals or the generated temperature maps to produce control signals; d) controlling the operation of the furnace with the furnace controller using the produced control signals.

14. The method of claim 13, wherein step a) and b) are performed by a CCD camera.

15. The method of claim 13, wherein only field signals from zones corresponding to selected components of the furnace are treated by the signal processing unit.

16. The method of claim 13, wherein the algorithm is run on a cloud-based server.

17. The method of claim 13, wherein the span of time covers multiple operation steps of the furnace.

18. The method of claim 17, wherein the multiple operation steps include feeding raw materials into the furnace through the charging port and discharging the residues from the discharging port.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are to be understood as examples of the present invention, and do not in any way limit the scope thereof.

[0031] FIG. 1 is a schematic representation showing components of a furnace monitoring and controlling system.

[0032] FIG. 2 is a flow chart indicating the steps of the present invention.

[0033] In FIG. 1, the reference numbers indicate the following features: 1—furnace, 2—CCD camera, 3—signal processing unit, 4—analyzing unit, 5—furnace controller, 6—burner, 7—loading port, 8—discharging port, 9—flue gas channel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In the illustrated embodiment, a thermal imaging apparatus using multiple infrared wavelengths is employed to obtain fast and accurate temperature mapping of the full field of the furnace during furnace operation. For example, the thermal imaging apparatus comprises a CCD camera, which sends field signals to a beam splitter. One beam was to be used to optically focus the camera; the other beam was to be sent to a signal processing unit, such as a computer containing data processing software.

[0035] In the present context, “Field signals” refer to the mapping of a parameter over a 2-D or 3-D area or zone of interest, in contrast to punctual or “spot” signals measuring a parameter at an individual point only.

[0036] The CCD camera is disposed at a location capable of capturing signals from all areas of interest, including the burner, all viewing, loading and discharging ports, as well as flue gas channels. The collected IR field signals are digitally processed into artificial-color temperature maps (whereby different colors indicate different temperatures), which can be stored or displayed on a monitor. Monitors or other displaying means may be located in vicinity to the furnace or away from the furnace in a remote area.

[0037] The measuring field of the CCD camera is divided into different zones corresponding to selected components of the furnace, such as the loading port, the discharging port, burner, viewing ports for observing the burner and the flue gas channel. According to an embodiment of the invention, only field signals from zones corresponding to such selected components are collected and processed by the signal processing unit. In this way, data sensitivity and data processing speed can be increased and the resulting temperature maps are dearer for operators.

[0038] Operators, who view the temperature map of the furnace at either a local or a remote location, can compare the measured temperature(s) with set temperature(s) of the furnace, corresponding to a standard or desired furnace operation, and adjust operational parameters according to his/her experiences or set protocols. Accurate temperature measurements are, for example, obtained by comparing the pixel intensities at two distinct IR wavelengths. Near IR wavelengths of 700-800 nm may be used.

[0039] In addition to or instead of manual control by the operator(s), the digitally processed field signals or the temperature map are sent to the analyzing unit. In the analyzing unit, software based on incorporated control algorithms can be run either locally or remotely, for example on a cloud-based server, to produce control signals capable of performing various functions. The control algorithms may, in particular, produce control signals in order to minimize differences between field temperature set points and measured field temperatures. The software allows storage of data and review of historical information. The control signals are transmitted to the furnace controller for controlling the furnace either in a closed loop or open loop fashion both to keep operation parameters within safe or in-control limits and to automatically tune them to pre-set values or to quickly respond to warning signs. For doing so, the analyzing unit may compare the actual data values to alarm or alert threshold values to determine whether alerts are desirable or required, and may also analyze combinations of sensor data against a theoretical and/or experimental database to determine whether maintenance intervention is required or another condition exists that requires attention. Such analysis and alarm determination may be performed by a cloud computing system. The alerting can be done via any standard method, including through the use of lights or audible alarms in the control room, at the burner, at the flow control skid, or at any other convenient location. The furnace controller can be a primary or an auxiliary controller, which is configured to receive the control signals to assist with furnace control.

[0040] With the above-described furnace monitoring and controlling system, field temperature data of furnace exteriors and loads are generated in essentially real time and can be obtained or stored over a period of time covering various process steps. A mathematical model or simulation is constructed based on historical data for more optimal operation conditions. Through comparison with the optimized database, field control is performed. Field control works in conjunction with traditional controllers to provide adjustments to mitigate hot spots and instabilities and to optimize combustion performance. Field control consists not of matching set points of a limited number of measurements, but of minimizing the difference between a set of field set points and actual field measurements.

[0041] The field signals and generated temperature map not only make it possible to monitor the safe operation of the furnace and to determine whether maintenance intervention is required. The field signals and/or generated temperature map may also be used to optimize the furnace operation.

[0042] For example, the control algorithms may determine needed adjustments to air/fuel ratio, to the firing rate for all or some of the burners, to the sequence and frequency of loading and discharging, as well as to the time intervals for each process step.

[0043] For example, field signals corresponding to a burner or to a viewing port for a burner make it possible to verify in near real-time the proper operation of the burner concerned and to identify any malfunction (such as flame extinction or flame deviation) or scope for optimization (such as an increased or decreased firing rate in order to obtain a desired temperature profile in the furnace) on the basis of the field signal corresponding to the burner or the viewing port or the corresponding zone of the generated temperature map.

[0044] Field signals corresponding to a charging port make it possible to observe in near real-time, on the basis of the field signal corresponding to charging port or the corresponding zone of the generated temperature map, whether the charging port is open or closed, whether the open port is fully open or the closed port is completely closed and the time during which the charging port is open. Due to the effect thereof the on the thermal image of the furnace, it may even be possible to observe, via said field signals or the generated temperature map, whether material (charge) is being fed to the furnace via the charging port and whether the charging port remains open significantly longer than required for feeding the charge.

[0045] Similarly, field signals corresponding to a discharging port make it possible to observe in near real-time whether the discharging port is open or closed, whether closure is complete and how long the discharging port remains open. It may even be possible to observe whether material is effectively being discharged via the discharging port, including whether there is a time lapse between the opening of the discharging port and the start of material being discharged and/or whether there is a time lapse between when discharging is terminated and the closure of the discharging port.

[0046] The time during which a furnace port, in particular a charging or discharging port, remains open during a production cycle is an important factor with respect to furnace performance. Indeed, open ports can cause significant heat losses and the ingress of important amounts of unheated nitrogen-containing ambient air. Keeping the duration during which ports are open to a minimum can thus significantly improve furnace efficiency.

[0047] Field signals corresponding to the flue gas channel and the corresponding zone of the generated temperature map provide an indication in near real-time of the level of heat losses via the flue gas channel. In addition, when the flue gas channel includes a post-combustion zone in which combustible substances present in the flue gas are combusted with oxidant, the field signals corresponding to the post-combustion zone in the flue gas channel and the corresponding zone of the temperature map may provide in near real-time an indication of (changes in) the levels of combustible substances in the flue gas evacuated from the furnace.

[0048] The field signals generated by the thermal imaging apparatus and the temperature map generated by signal processing unit thus provide in near real-time important information regarding the operation of the furnace, any abnormalities and opportunities for improving the efficiency of furnace operation.

[0049] Consequentially, objectives such as increased thermal efficiency, lower NOx emissions, elimination of hot spots, and prevention of shutdowns are achieved. In all embodiments, signals are transmitted via wires or a network such as Internet, an intranet, a local area network (LAN), and a wide area network (WAN), with wired and/or wireless communication. The data processing unit may include a local or cloud-based server, where data can be archived and from which data can be retrieved. FIG. 1 illustrates a furnace monitoring and controlling system of the present invention. An exemplary furnace 1 includes a furnace body, a burner 6, a loading or charging port 7, a discharging port 8 and a flue gas channel 9. Whereas, only one burner is shown in the figure, furnaces may comprise multiple burners and all or some of said burners (preferably all) may be monitored using the furnace monitoring or controlling system of the present invention. The loading port 7 is opened for feeding raw materials into the furnace and closed after the feeding is completed. Likewise, the discharging port 8 is opened and closed for unloading product from the furnace. Their open duration, relative sequence and time intervals in between steps have an impact on the energy efficiency of the furnace performance. At least one thermal imaging apparatus, in this case, a CCD camera 2 is placed at a predetermined location outside of the furnace, which enables it to take measurements of the selected components of the furnace. Since the signals are collected over the entire field; and not focused on a few distinctive points, the signals are referred to as field signals. Such field signals are transmitted to a signal processing unit 3 either through hardwires or wireless network. The signal processing unit 3 converts the field signals into a temperature map and the map is displayed either through an integrated display device or sent out to a remote display device (HMI), such as a cellular phone for the operators to view. When more controlling functions are desired, the temperature map or the raw field signals are fed into an analyzing unit 4, which utilizes a control algorithm to produce control signals based on comparison with data for ideal operational condition. The analyzing unit 4 can be a stand-alone computer or is combined with the signal processing unit 3 into one piece of equipment. The control signals are then transmitted to a furnace controller 5 to facilitate its control over the operation of the furnace. Normally, the furnace controller 5 relies on signals from other sensors to practice primary control and the signals originally captured by the thermal imaging apparatus serve as source for auxiliary control.

[0050] The steps for monitoring and controlling the furnace are summarized in the flowchart of FIG. 2.

[0051] Although this invention has been described in detail with reference to certain embodiments, those skilled in the art will recognize that variations and modifications of the described embodiments may be used. Accordingly, these variations and modifications are also within the spirit and scope of the invention as defined by the appended claims and their equivalents.