Furnace control system using thermal imaging

Abstract

The present disclosure provides a control system (200) for an electric furnace (210) with a radiative heating system for heating a process fluid in a process coil (110). The control system comprises a thermal imaging camera (240) positioned outside the electric furnace (210) and configured to receive thermal radiation from a plurality of zones (250) in the furnace, wherein each zone is defined by a respective section of the process coil arranged with at least one heating component (120a, 120b, 120c, 120d) of the radiative heating system. A control unit (220) is adapted to control each of the heating components independently and is configured to receive temperature information for each zone from the thermal imaging camera and generate control signals to change at least one of a heating setting of at least one heating component in at least one zone and a flow rate of the process fluid.

Description

[0001] SP3222

[0002] 1

[0003] FURNACE CONTROL SYSTEM USING THERMAL IMAGING

[0004] Field of the Invention

[0005] The present disclosure relates to control systems for electric furnaces, and more particularly to a control system, method, and use of a thermal imaging camera for controlling a radiative heating system in an electric furnace using temperature information from multiple zones. Background of the Invention

[0006] Electric furnaces are used in various industrial processes for heating materials and fluids. These furnaces typically employ resistive heating elements to generate heat, which is then transferred to the process fluid flowing through coils or tubes within the furnace. The heating elements are arranged in specific configurations to provide heating throughout the furnace chamber.

[0007] Temperature control in general (not necessarily electric ) furnaces is traditionally achieved using thermocouples placed at strategic locations within the furnace or on the process coils. These thermocouples measure the temperature at specific points and provide feedback to a control system, which adjusts the power supplied to the heating elements accordingly. This method of temperature control has been utilized for many years in industrial heating applications.

[0008] One challenge associated with conventional temperature control methods in furnaces is the limited spatial resolution of temperature measurements.

[0009] Thermocouples provide temperature data only at discrete points, which may not accurately represent the temperature distribution across the entire furnace or process coil. This can lead to uneven heating and potential hot spots,which may affect the quality of the heated product or reduce the efficiency of the heating process.

[0010] Another issue with traditional temperature control systems is the difficulty in detecting and responding to rapid temperature changes or localized heating anomalies. The thermal inertia of the furnace refers to its resistance to temperature changes, which can result in slower heating or cooling responses. Additionally, there may be a time delay between when a temperature change occurs and when it is detected by a thermocouple. These factors can result in slower response times to temperature fluctuations, potentially leading to suboptimal process control or safety concerns.

[0011] Furthermore, the placement of thermocouples on or near the process coils can be challenging, especially in high-temperature environments or with complex coil geometries. The thermocouples may be subj ect to wear, damage, or drift over time, requiring frequent maintenance or replacement and potentially causing process interruptions.

[0012] It has been appreciated that a furnace control system is needed that addresses one or more of these problems.

[0013] Summary of the Invention

[0014] In a first aspect, a control system for an electric furnace for heating a process fluid in a process coil located inside the furnace is provided. The control system includes: a thermal imaging camera positioned outside of the electric furnace and configured to receive thermal radiation from a plurality of zones in the electric furnace, wherein each zone of the plurality of zones is defined by a respective section of the process coil arranged with at least one heating component; and a control unit adapted to control each of the heatingcomponents independently, and configured to: receive temperature information for each zone of the plurality of zones from the thermal imaging camera; and generate control signals to change at least one of a heating setting of at least one heating component in at least one zone of the plurality of zones and a flow rate of the process fluid. The camera may be provided with a borescope. The borescope may stretch into the furnace, so that the camera has a direct line of sight to the process coil and heating components.

[0015] This control system provides advantages for electric furnaces used in industrial processes. By utilizing a thermal imaging camera positioned outside the furnace, the system can obtain comprehensive temperature information across multiple zones without the need for intrusive sensors inside the high-temperature environment. This noncontact approach enhances reliability and reduces maintenance requirements. The independent control of heating components in different zones allows for precise and localized temperature management, which can lead to improved process efficiency, reduced energy consumption, and extended equipment lifespan. The ability to adjust both heating settings and fluid flow rate provides flexibility in responding to various process conditions, enabling optimization of heat transfer and product quality.

[0016] The control system may be applied to various types of furnaces, including those using different heating methods. However, it has been found that the control system works particularly well with electric furnaces. Electric furnaces can be built to allow for zonal control, enabling independent adjustment of multiple heating zones. This capability can be efficiently managed using electrical control means such as power modulation. Theprecise and rapid control afforded by electrical systems in electric furnaces may enhance the effectiveness of the temperature management provided by the thermal imaging and control unit combination.

[0017] The electric furnace may comprise a radiative heating system. Utilizing a radiative heating system in the electric furnace allows for efficient and uniform heat transfer to the process fluid, which can result in improved energy efficiency and more consistent product quality.

[0018] The control system may further comprise at least one thermocouple arranged in at least one of an inlet part or an outlet part of the electric process coil, and / or at least one thermocouple arranged in a location inside the furnace inside the process coil, and / or at least one thermocouple arranged in a location inside the furnace outside the process coil.

[0019] The inclusion of thermocouples provides additional temperature data points, complementing the thermal imaging information and allowing for a more comprehensive understanding of the temperature profile throughout the furnace and process fluid path. Thermocouples positioned inside the process coil can provide direct measurements of the fluid temperature and heat transfer conditions within the coil, while thermocouples outside the coil can capture information about the overall furnace environment and heating element performance. This combination of internal and external temperature measurements enables the control system to distinguish between temperature variations caused by changes in the process fluid conditions versus those resulting from fluctuations in the furnace heating elements or ambient conditions.

[0020] The control unit may be further configured to receive data from the at least one thermocouple andcompare the temperature information for each zone of the plurality of zones with the data from the at least one thermocouple. This comparison of data from multiple sources enhances the accuracy and reliability of temperature measurements, enabling more precise control and potential detection of anomalies or discrepancies in temperature readings.

[0021] The control unit may be configured to generate control signals to change a power supply to the at least one heating component in at least one zone of the plurality of zones. This feature allows for fine-tuning of heat input in specific zones, enabling targeted temperature control and potentially reducing overall energy consumption.

[0022] The control unit may be configured to generate control signals to change the flow rate of the process fluid received in the inlet part of the electric furnace. Adj usting the flow rate provides an additional means of controlling the heat transfer process, allowing for optimization of residence time and temperature profile of the process fluid.

[0023] The thermal imaging camera may be further configured to generate an image including the temperature information for each zone of the plurality of zones in the electric furnace. Visual representation of temperature distribution can aid in quick identification of hot spots or temperature anomalies, facilitating rapid decision-making and troubleshooting.

[0024] The control unit may be configured to detect that a temperature of at least one zone of the plurality of zones is not within a predetermined temperature range for the at least one zone. This capability enables proactive identification of potential issues, allowing for timelyinterventions to maintain optimal process conditions and prevent equipment damage.

[0025] Upon detecting that a temperature of a first zone is higher than the predetermined temperature range for the first zone, the control unit may be configured to generate a control signal to reduce the power supply to the at least one heating component in the first zone and / or to increase the flow rate of the process fluid. This automated response helps prevent overheating, reducing the risk of product degradation or equipment damage while maintaining process continuity.

[0026] The control unit may be further configured to generate a control signal to increase or maintain the power supply to the at least one heating component in a second zone adjacent to the first zone. This feature allows for zonal control, e. g. for compensatory heating in adjacent zones, helping to maintain overall process temperature while addressing localized temperature excursions.

[0027] In a second aspect, a method for controlling heating parameters of an electric furnace for heating a process fluid in a process coil located inside the furnace is provided. The method comprises: receiving, from a thermal imaging camera, temperature information for each zone of a plurality of zones in the electric furnace, wherein each zone of the plurality of zones is defined by a respective section of the process coil arranged with at least one heating component; generating control signals for each zone of the plurality of zones based on the temperature information; and changing at least one of a heating setting of the at least one heating component in each zone of the plurality of zones, independently of each other, and a flow rate of the process fluid. This method provides a systematic approach to managing the heating process inelectric furnaces, allowing for dynamic adjustments based on real-time temperature data across multiple zones.

[0028] The method may further comprise receiving, from at least one thermocouple, data including a temperature of the process fluid at the inlet and outlet of the electric furnace. Incorporating thermocouple data provides additional context for temperature control decisions, enhancing the overall accuracy of the control system.

[0029] The method may further comprise: comparing the temperature information for each zone of the plurality of zones and the data from the at least one thermocouple; and detecting that at least one of a temperature of the process fluid in an inlet part of the electric furnace, a temperature of the process fluid in an outlet part of the electric furnace, and a temperature of at least one zone of the plurality of zones is not within a respective predetermined temperature range. This comparative analysis and detection capability enables the system to identify and respond to temperature deviations at multiple points in the process.

[0030] The method may further comprise: upon detecting that a temperature of a first zone is higher than the predetermined temperature range for the first zone, reducing the power supply to the at least one heating component in the first zone; and increasing or maintaining the power supply to the at least one heating component in a second zone adjacent to the first zone. This responsive action helps maintain overall process stability while addressing localized temperature issues.

[0031] In a third aspect, use of a thermal imaging camera for controlling a radiative heating system in an electric furnace is provided. The use comprises: positioning the thermal imaging camera outside of the electric furnace; receiving thermal radiation from a plurality of zones inthe electric furnace using the thermal imaging camera, wherein each zone of the plurality of zones is defined by a respective section of a process coil arranged with at least one heating component of the radiative heating system; generating temperature information for each zone of the plurality of zones based on the received thermal radiation; and controlling the radiative heating system based on the generated temperature information.

[0032] Controlling the radiative heating system may comprise independently adjusting at least one of a heating setting of the at least one heating component in each zone of the plurality of zones and a flow rate of a process fluid in the process coil. This independent zonal control capability allows for precise temperature management and process optimization, potentially leading to improved product quality and energy efficiency.

[0033] Brief Description of the Figures

[0034] Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:

[0035] Fig. 1A illustrates a top view of a furnacesection showing heating components and a process coil, according to an embodiment of the present disclosure.

[0036] Fig. 1B illustrates another side top of a furnacesection showing heating components and a process coil, according to an embodiment of the present disclosure.

[0037] Figure 1C illustrates a further top view of a furnacesection showing heating components and a process coil according to an embodiment of the present disclosure.

[0038] Fig. 2 illustrates a side view of a furnacesection including a control system, according to an embodiment of the present disclosure.

[0039] Common reference numerals are used throughout the figures to indicate similar features.Detailed Description of the Invention

[0040] The present disclosure relates to a control system for an electric furnace, preferably with a radiative heating system. The control system is designed to heat a process fluid flowing through a process coil located inside the furnace. This control system can be implemented in various types of furnaces, including electric furnaces that utilize resistive heating elements.

[0041] The control system incorporates advanced monitoring and control capabilities to optimize the heating process and maintain desired temperature conditions within the furnace. By employing a combination of thermal imaging technology and temperature sensors, the system can accurately monitor and regulate the temperature distribution across different zones of the furnace.

[0042] One of the primary components of the control system is a thermal imaging camera positioned outside the furnace. This camera captures thermal radiation emitted from various zones within the furnace, providing real-time temperature information for different sections of the process coil. The thermal imaging data allows for precise monitoring of temperature variations across the furnace interior.

[0043] As used herein, the term "thermal imaging camera" may refer to a device that detects infrared radiation emitted by obj ects and converts it into a visible image representing the temperature distribution across the obj ect ' s surface. The thermal imaging camera may capture two-dimensional (2D) temperature data, creating a heat map of the observed area. Examples of thermal imaging cameras may include bolometer-based cameras, quantum well infrared photodetector (QWIP) cameras, and microbolometer array cameras. In some cases, the thermal imaging camera may utilize uncooled focal plane array ( FPA) technology orcooled detector systems for enhanced sensitivity. The camera may operate in various infrared wavelength ranges, such as near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR), or long-wave infrared (LWIR), depending on the specific application requirements and temperature ranges being monitored.

[0044] In addition to the thermal imaging camera, the control system may optionally include temperature sensors, such as thermocouples, strategically placed to measure process fluid temperatures at specific points, such as the inlet and outlet of the furnace. These sensors provide complementary temperature data to enhance the overall monitoring capabilities of the system. The control system may optionally be in communication with another control system (for example a legacy or standard control system of an electric furnace that is later enhanced with a IR camera to form a system according the invention) connected to these thermocouples. Additionally, thermocouples may be used to measure furnace atmospheric temperature.

[0045] A control unit serves as the central processing component of the control system. This unit receives and analyses the temperature information from both the thermal imaging camera and any additional temperature sensors. Based on this data, the control unit generates appropriate control signals to adjust the heating parameters of the furnace and / or the flow rate of the process fluid in the process coil.

[0046] The control system is capable of independently regulating multiple heating components within the furnace. This allows for precise control of temperature conditions in different zones of the furnace, enabling optimization of the heating process based on specific requirements of the process fluid and desired output conditions.By integrating these various components and functionalities, the control system provides an improved solution for managing and optimizing the heating process in furnaces with radiative heating systems. The system's ability to monitor and control temperature conditions across different zones of the furnace contributes to improved efficiency, product quality, and overall process control in industrial heating applications.

[0047] FIG. 1A illustrates a top view of of a furnacesection ( 100 ), showing the x-y plane. The furnacesection ( 100 ) includes a process coil ( 110 ) arranged in a serpentine configuration between heating components. The heating components comprise a first heating component ( 120a ), a second heating component ( 120b ), a third heating component ( 120c ), and a fourth heating component ( 120d). These heating components are arranged in pairs on opposing sides of the process coil ( 110 ), with the first heating component ( 120a ) and the second heating component ( 120b ) positioned on one side, and the third heating component ( 120c ) and the fourth heating component ( 120d ) positioned on the opposite side.

[0048] Each heating component is associated with a corresponding power supply control element. A first power supply control element ( 130a ) is connected to the first heating component ( 120a ), a second power supply control element ( 130b ) is connected to the second heating component ( 120b ), a third power supply control element ( 130c ) is connected to the third heating component ( 120 c ), and a fourth power supply control element ( 130d ) is connected to the fourth heating component ( 120d ).

[0049] The process coil ( 110 ) extends primarily along the direction of the x axis, with the inlet section ( 211 ) positioned on one side and the outlet ( 212 ) on the opposite side. The other main dimension of the processcoil ( 110 ) extends along the z direction, which is perpendicular to the plane of the figure. This arrangement results in the coil appearing as one-dimensional in the present projection. Figure 1A defines two distinct heating zones, each characterized by heating elements positioned on either side of the process coil ( 110 ), so four heating elements in total. This configuration may allow for more uniform heating of the process fluid as it flows through the serpentine path of the coil, with the heating components on both sides providing thermal energy to the fluid within each section.

[0050] FIG. 1B illustrates a top view of a different furnace section ( 100 ). This configuration is similar to FIG. 1A, but the furnacesection ( 100 ) now includes three heating zones, each defined by a section of the process coil ( 110 ) arranged with heating components. In this arrangement, the heating components 120a, 120d, and 120e (with corresponding power supply control elements 130a, 130d, 130e ) are positioned on one side of the process coil ( 110 ) only, resulting in a total of 3 heating components. It is worth noting that it is also possible to have heating components on both sides of the process coil (110 ) as shown in FIG. 1A, which would result in a total of 6 heating components.

[0051] FIG. 1C depicts an arrangement that is identical to FIG. 1B, with one key difference. In this configuration, the heating components are positioned on alternating sides of the process coil ( 110 ). Specifically, heating component 120c (for zone 2 ) is placed opposite to heating components 120a for zone 1 and heating component 120e for zone 3. This alternating arrangement may provide more uniform heating distribution along the length of the process coilThe configurations shown in FIG. 1B and FIG. 1C offer different approaches to zonal heating control. The single-sided arrangement in FIG. 1B may be beneficial for certain furnace designs or maintenance accessibility, while the alternating arrangement in FIG. 1C may provide advantages in terms of heat distribution and temperature uniformity across the process coil ( 110 ). The choice between these configurations would depend on specific application requirements and operational considerations.

[0052] A zone may be defined as a volume in the furnacesection ( 100 ) containing a portion of the process coil ( 110 ) and one or more heating components. Each zone of the plurality of zones is defined by a respective section of the process coil ( 110 ) arranged with at least one heating component. The number and arrangement of heating components within a zone may vary depending on the specific heating requirements of the process. A

[0053] dashed line between adjacent heating elements in Figures 1A - 1C represents a plane separating two adjacent zones. This plane is typically perpendicular to the average direction of flow in the process coil ( 110 ). For example, in Figure 1A, the line separates the zone primarily heated by the first pair of heating components ( 120a, 120b) from the zone primarily heated by the second pair of heating components ( 120c, 120d). Similarly, in Figure 1B, the line separates the zone influenced by the first heating component ( 120a ) from the zone influenced by the third heating component ( 120d).

[0054] The power supply control elements ( 130a, 130b, 130c, 130d) enable independent control of the single or multiple heating components for each zone, allowing for precise temperature management within each zone. This zonal control may facilitate optimization of the heating process based on specific requirements of different sections ofthe process coil ( 110 ). It should be noted that the heating components may also be referred to as heating panels in this disclosure. One way to control the power supplied to these heating components or panels is by controlling the duty cycle. The duty cycle refers to the proportion of time a heating component is active within a given period. For example, a 50% duty cycle means the heating component is on for half the time and off for the other half. By adjusting the duty cycle, the overall power supplied to each heating component can be precisely controlled, allowing for fine-tuned temperature management in each zone.

[0055] FIG. 2 illustrates a control system (200 ) for monitoring and controlling an electric furnace (210 ). The electric furnace (210 ) includes an inlet part ( 211 ) and an outlet part (212 ), with process coils arranged in multiple furnace zones ( 250 ), comprising a first zone (251 ), a second zone (252 ), and a third zone (253 ). This figure represents a side view in the x-z plane, where the process coil runs primarily in the x direction while meandering up and down in the z direction. In this projection, the heating components and corresponding zones appear as two-dimensional surfaces. The heating components can be positioned on either or both sides of the coil, allowing for flexible heating configurations throughout the furnace.

[0056] In the current example, the bends of the process coil fall outside the defined zones. However, it may be noted that the bends could also fall inside the zones in alternative configurations. The heating components may overlap with the zones, and their size may vary relative to the zone dimensions. In some cases, the heating components may be larger or smaller than the zones they are associated with.Referring to the example illustrated in Figure 2, each zone encompasses 4 passes of the process coil - two upward passes and two downward passes along the z-axis. This arrangement is provided as an example, and it may be appreciated that any number of passes per zone is possible. The number of passes per zone may include fractional passes, though for control purposes, it may be more convenient to have an integer number of passes. For instance, configurations may include 1 pass per zone, 2 passes per zone, 3, 4, 5, 6, or more passes per zone, depending on the specific design requirements and operational considerations of the furnacesystem.

[0057] A control unit ( 220 ) serves as the central processing component of the control system (200 ). The control unit (220 ) receives input from multiple monitoring devices and processes this information to generate control signals for managing the electric furnace (210) operations.

[0058] A thermal imaging camera (240 ) is positioned outside of the electric furnace (210 ) and configured to receive thermal radiation from the furnace zones (250 ). The thermal imaging camera (240 ) transmits data to an IR data processing unit (245 ). The IR data processing unit ( 245 ) processes the thermal imaging data to extract temperature information for each zone of the electric furnace (210) and forwards this processed information to the control unit (220 ). The thermal imaging camera (240 ) may generate an image including the temperature information for each zone in the electric furnace (210 ).

[0059] A thermocouple ( 230 ) is arranged to measure process fluid temperatures. The thermocouple (230 ) may be positioned in at least one of the inlet part (211 ) or the outlet part (212 ) of the electric furnace (210). The thermocouple (230 ) is configured to determine atemperature of the process fluid outside the electric furnace (210 ) and provide this data to the control unit (220 ).

[0060] The control unit (220 ) processes the inputs from the thermal imaging camera (240 ) and thermocouple ( 230 ) to generate control signals. The control unit (220 ) may compare the temperature information for each zone with the data from the thermocouple ( 230 ). Based on this analysis, the control unit (220 ) may detect if a temperature of at least one zone is not within a predetermined temperature range for that zone.

[0061] The control signals generated by the control unit (220 ) are sent to further process control equipment (260 ) which implements the necessary adjustments to maintain desired operating conditions within the electric furnace (210 ). These adjustments may include changes to the heating settings of heating components in one or more zones, changes to the flow rate of the process fluid, or changes to the power supply of heating components.

[0062] For example, if the control unit ( 220 ) detects that a temperature of the first zone (251 ) is higher than the predetermined temperature range for that zone, the control unit (220 ) may generate a control signal to reduce the power supply to the heating component in the first zone (251 ). Simultaneously, the control unit ( 220 ) may generate a control signal to increase the flow rate of the process fluid to help reduce the temperature in the first zone (251 ). The control unit (220 ) may also consider the outlet temperature measured by the thermocouple (230 ) when determining these adjustments. If the outlet temperature is below the desired range, the control unit (220 ) may moderate the reduction in power supply to the first zone (251 ) or increase power to other zones to maintain anappropriate overall heat input while addressing the localized high temperature in the first zone (251 ).

[0063] Additionally, the control unit (220 ) may generate a control signal to increase or maintain the power supply to the heating component in the second zone (252 ) adjacent to the first zone (251). This allows for independent control of each heating component, enabling precise temperature management across different zones of the electric furnace (210 ). By increasing the power supply in a second zone while decreasing the power supply in a first zone, the overall energy input into the furnace can be kept constant. At the same time, by rebalancing the power input per zone, the temperature profile in the process coil may be improved. For example, it can be made more homogeneous.

[0064] The control unit (220 ) may also generate control signals to change the flow rate of the process fluid received in the inlet part ( 211 ) of the electric furnace (210 ). This provides another mechanism for temperature control within the electric furnace (210 ). Adjusting the flow rate typically has a large effect on overall process quality. In an embodiment, the flow rate is kept constant (at a predetermined rate) and only adjusted in case adjustments to the power supplied to the zones is insufficient to bring the temperature within the process coil within an pre-determined target range.

[0065] By integrating these various components and functionalities, the control system (200 ) provides a solution for monitoring and controlling temperature conditions across different zones of the electric furnace (210 ). This system enables efficient management of the heating process, contributing to improved process control in industrial heating applications.

[0066] The control system utilizes a decision-based logic to determine setpoints and adjust control parameters basedon temperature readings from thermocouples and a thermal imaging camera. Table 1 below illustrates example scenarios and corresponding actions taken by the control system in a three-zone furnace configuration:H Scenario T output IR Zone 1 IR Zone 2 IR Zone 3 Action SU CT

[0067] Reading Reading Reading Reading CD Redistribute Optimal High Optimal Optimal Redistribute heating panels duty

[0068] Duty

[0069] Increase Duty Optimal Optimal Optimal Optimal Possibility to increase overall duty to increase throughput (keep eye on IR readings)

[0070] Redistribute Optimal Low Optimal Optimal Redistribute heating panels duty non- non-uniformly (increase in zone 1,

[0071] decrease in other zones)

[0072] Reduce and High High Optimal Optimal Reduce overall duty £ redistribute Redistribute heating panels duty

[0073] Duty

[0074] Reduce Duty High Optimal Optimal Optimal Reduce overall duty uniformly

[0075] Reduce Duty High Dow Optimal Optimal Reduce overall duty non-uniformly (larger decrease In ’ optimal ' zones) Increase and Low High Optimal Optimal Increase overall duty (keep eye on IR Redistribute readings) & redistribute heating

[0076] Duty panels duty (decrease in zone 1,

[0077] increase in other zones)

[0078] Increase Duty Low Optimal Optimal Optimal Increase duty uniformly (keep eye on IR readings)

[0079] Increase Duty Low Low Optimal Optimal Increase overall duty non-uniformly (largest increase in zone 1)

[0080]

[0081] The control system can redistribute heating duty between zones based on temperature readings from the thermal imaging camera and thermocouples. For example, in the first scenario of Table 1, when the output temperature is optimal but the IR reading in Zone 1 is high, the control system redistributes the heating panel duty. This may involve reducing the power supply to heating components in Zone 1 while maintaining or increasing the power supply in other zones to maintain the optimal overall energy input.

[0082] In scenarios where all temperature readings are optimal, the control system may increase the overall duty to improve throughput. However, the system continues to monitor IR readings to ensure temperatures remain within acceptable ranges. This demonstrates how the control system can adjust overall heating duty based on temperature readings to optimize the process.

[0083] The control system can also respond to non-uniform temperature distributions across zones. For instance, when Zone 1 shows a low temperature while other zones are optimal, the system redistributes heating panel duty non-uniformly. This may involve increasing power supply to heating components in Zone 1 while decreasing power in other zones to maintain the optimal output temperature. This redistribution may be implemented on the condition that there have been no hot spots previously detected and / or it is determined to be safe to increase the duty in Zone 1.

[0084] When the output temperature is high and Zone 1 temperature is also high, the control system reduces overall duty and redistributes heating panel duty. This action aims to bring the output temperature back to the optimal range while addressing the high temperature in Zone 1.In situations where the output temperature is high but all zone temperatures are optimal, the control system may reduce the overall duty uniformly across all zones. This action helps bring the output temperature back to the optimal range while maintaining the balanced temperature distribution within the furnace.

[0085] The system can also respond to more complex temperature profiles. For example, when the output temperature is high but Zone 1 temperature is low, the control system may reduce the overall duty non-uniformly. In this case, it may implement a larger decrease in power supply to the ' optimal ' zones while maintaining or only slightly reducing power to Zone 1. This approach helps address the high output temperature while preventing Zone 1 from becoming too cool.

[0086] In scenarios where the output temperature is low, indicating potential underheating, the control system may take various actions to increase the overall temperature. When the output temperature is low but Zone 1 temperature is high, the system may increase the overall duty while redistributing heating panel duty. This may involve decreasing power supply to Zone 1 while increasing it in other zones, aiming to raise the overall temperature while addressing the localized hot spot. Again, this redistribution may be implemented on the condition that there have been no other hot spots previously detected and / or it is determined to be safe to increase the duty in the selected other zone ( s ).

[0087] When the output temperature is low and all zone temperatures are optimal, the control system may increase duty uniformly across all zones. This action helps raise the overall temperature while maintaining the balanced temperature distribution within the furnace. The systemcontinues to monitor IR readings closely during this process to ensure no zones become overheated.

[0088] In cases where both the output temperature and Zone 1 temperature are low, the control system may increase the overall duty non-uniformly. This approach involves implementing the largest increase in Zone 1, with smaller increases in other zones as needed. This strategy aims to quickly address the low temperature in Zone 1 while also raising the overall output temperature to the optimal range. Again, this can be on the condition that there have been no hot spots previously detected in the zones where duty will be increased and / or it is determined to be safe to increase the duty in those zones.

[0089] In addition to duty cycle control, the control system may employ various other methods to regulate power and temperature within the furnace. For example, the system may utilize voltage or current modulation to adjust the power supplied to the heating components. By varying the voltage or current, the control unit can fine-tune the heat output of each zone independently.

[0090] In addition to duty cycle control, the control system may employ various other methods to regulate power and temperature within the furnace. For example, the system may utilize voltage or current modulation to adjust the power supplied to the heating components. By varying the voltage or current, the control unit can fine-tune the heat output of each zone independently.

[0091] Optionally, The control system may also incorporate phase angle control, where the power supplied to the heating elements is regulated by adjusting the phase angle of the AC power supply.

[0092] In some cases, the system may employ pulse width modulation ( PWM) techniques to control the power output. PWM allows for rapid switching of the power supply,effectively controlling the average power delivered to the heating components. This method may provide more responsive temperature control compared to simple on / off cycling.

[0093] The control unit may also implement adaptive control algorithms that adjust heating parameters based on historical data and predictive models. These algorithms may take into account factors such as thermal inertia, heat transfer rates, and process fluid properties to optimize heating efficiency and temperature stability across the furnace zones.

[0094] In certain applications, the system may utilize a combination of different control methods, selecting the most appropriate technique based on the specific requirements of each zone or process condition. This hybrid approach may allow for more flexible and efficient temperature management throughout the furnace.

[0095] The control system can adjust maximum temperature setpoints after optimal running hours for maintenance, decoking, and increased tube lifetime. While not explicitly shown in Table 1, this feature may be implemented as part of the control system's long-term operational strategy. For example, after a predetermined number of operating hours, the control system may automatically lower the maximum allowable temperature for each zone to extend the time between maintenance cycles and prolong the life of the process coils.

[0096] The control unit uses a decision-based logic to determine setpoints based on thermocouple and thermal imaging camera data. This logic is exemplified in Table 1, where different combinations of temperature readings lead to specific control actions. The decision-based logic allows the control system to respond dynamically to changing conditions within the furnace.It is important to note that the three-zone example presented in Table 1 is j ust one possible configuration. The control system may be adapted to furnaces with different numbers of zones, and the specific actions taken in response to temperature readings may be customized based on the requirements of the particular process and furnace design.

[0097] In an alternative embodiment, the control system utilizes multiple thermal imaging cameras positioned outside the furnace. These cameras are arranged to capture thermal radiation from overlapping zones within the furnace, providing comprehensive coverage of the entire furnace interior.

[0098] The use of multiple thermal imaging cameras allows for enhanced temperature monitoring across the furnace. Each camera may be positioned to focus on specific sections of the process coil, with overlapping fields of view between adjacent cameras. This configuration ensures that every portion of the process coil is monitored by at least two cameras, providing redundancy and improving the accuracy of temperature measurements.

[0099] The control unit receives temperature information from all thermal imaging cameras simultaneously. By processing data from multiple cameras covering overlapping zones, the control system can cross-reference temperature readings and generate a more precise thermal map of the furnace interior. This approach may help to eliminate potential blind spots and reduce the impact of any single camera ' s measurement errors or limitations.

[0100] The overlapping coverage provided by multiple cameras may also enhance the system's ability to detect temperature gradients and localized hot spots within the furnace. By comparing temperature data from different angles and perspectives, the control system can moreaccurately identify areas of concern and implement targeted adjustments to heating parameters.

[0101] In this configuration, the control unit may employ advanced algorithms to reconcile and integrate temperature data from multiple cameras. These algorithms may account for factors such as viewing angle, distance from the monitored surface, and potential obstructions to ensure accurate temperature calculations across the entire furnace volume.

[0102] The use of multiple thermal imaging cameras may provide additional benefits in terms of system reliability. In the event that one camera experiences a malfunction or requires maintenance, the remaining cameras can continue to provide temperature monitoring, albeit with reduced coverage. This redundancy may help to minimize system downtime and maintain consistent process control.

[0103] Furthermore, the multi-camera configuration may allow for more frequent temperature measurements of each zone. As each camera can capture thermal data independently, the overall sampling rate of the system may be increased, potentially leading to more responsive and precise temperature control.

[0104] The control system may also leverage the multicamera setup to implement advanced temperature analysis techniques. For example, by comparing temperature readings from different cameras over time, the system may be able to detect trends or patterns in temperature distribution that might not be apparent from a single camera ' s perspective.

[0105] In some implementations, the multiple thermal imaging cameras may be of different types or have different specifications, allowing for a combination of wide-angle monitoring and high-resolution imaging ofspecific areas of interest. This approach may provide a balance between comprehensive coverage and detailed temperature analysis where needed.

[0106] The control unit may be configured to dynamically adjust the weighting or priority given to data from each camera based on factors such as the current operating conditions, historical performance, or specific process requirements. This adaptive approach to data integration may further enhance the system's ability to maintain optimal temperature conditions throughout the furnace.

[0107] Features of any of the examples or embodiments outlined above may be combined to create additional examples or embodiments without losing the intended effect. It should be understood that the description of an embodiment or example provided above is by way of example only, and various modifications could be made by one skilled in the art. Furthermore, one skilled in the art will recognise that numerous further modifications and combinations of various aspects are possible. Accordingly, the described aspects are intended to encompass all such alterations, modifications, and variations that fall within the scope of the appended claims.

Claims

2227C L A I M S1. A control system ( 200 ) for an electric furnace ( 210 ) for heating a process fluid in a process coil (110) located inside the furnace, the control system ( 200 ) comprising:a thermal imaging camera ( 240 ) positioned outside of the electric furnace ( 210 ) and configured to receive thermal radiation from a plurality of zones ( 250 ) in the electric furnace ( 210 ), wherein each zone of the plurality of zones ( 250 ) i s defined by a respective section of the process coil (110) arranged with at least one heating component (120a, 120b, 120c, 120d); anda control unit ( 220 ) adapted to control each of the heating components independently, and configured to: receive temperature information for each zone of the plurality of zones ( 250 ) from the thermal imaging camera ( 240 ); andgenerate control signals to change at least one of a heating setting of at least one heating component ( 120a, 120b, 120c, 120d) in at least one zone of the plurality of zones ( 250 ) and a flow rate of the process fluid.

2. The control system ( 200 ) of claim 1, wherein the electric furnace comprises a radiative heating system.

3. The control system ( 200 ) of claim 1 or 2, further comprising at least one thermocouple ( 230 ) arranged in at least one of an inlet part ( 211 ) or an outlet part ( 212 ) of the electric process coil (110), and / or at least one thermocouple arranged in a location inside the furnace inside the process coil, and / or at least one thermocouple arranged in a location inside the furnace outside the process coil.

4. The control system ( 200 ) of claim 3, wherein the control unit ( 220 ) is further configured to receive data from the at least one thermocouple (230) and compare the temperature information for each zone of the plurality of zones ( 250 ) with the data from the at least one thermocouple (230).

5. The control system ( 200 ) of any one of claims 1 to 4, wherein the control unit ( 220 ) is configured to generate control signals to change a power supply to the at least one heating component ( 120a, 120b, 120c, 120d ) in at least one zone of the plurality of zones ( 250 ).

6. The control system ( 200 ) of any one of claims 1 to 5, wherein the control unit ( 220 ) is configured to generate control signals to change the flow rate of the process fluid received in the inlet part ( 211 ) of the electric furnace ( 210 ).

7. The control system ( 200 ) of any one of claims 1 to 6, wherein the thermal imaging camera ( 240 ) is further configured to generate an image including the temperature information for each zone of the plurality of zones ( 250 ) in the electric furnace ( 210 ).

8. The control system ( 200 ) of any one of claims 1 to 7, wherein the control unit ( 220 ) is configured to detect that a temperature of at least one zone of the plurality of zones (250) is not within a predetermined temperature range for the at least one zone.

9. The control system ( 200 ) of claim 8, wherein, upon detecting that a temperature of a first zone ( 251 ) i s higher than the predetermined temperature range for the first zone ( 251 ), the control unit ( 220 ) is configured to generate a control signal to reduce the power supply to the at least one heating component (120a, 120b, 120c, 120d) in the first zone (251) and / or to increase the flow rate of the process f luid.

10. The control system ( 200 ) of claim 9, wherein the control unit ( 220 ) is further configured to generate a control signal to increase or maintain the power supply to the at lea st one heating component ( 120a, 120b, 120c, 120d) in a second zone ( 252 ) adjacent to the first zone (251).

11. A method for controlling heating parameters of an electric furnace ( 210 ) for heating a process fluid in a process coil (110) located inside the furnace, the method comprising:receiving, from a thermal imaging camera ( 240 ), temperature information for each zone of a plurality of zones ( 250 ) in the electric furnace ( 210 ), wherein each zone of the plurality of zones ( 250 ) is defined by a respective section of the process coil (110) arranged with at least one heating component (120a, 120b, 120c, 120d); generating control signals for each zone of the plurality of zones (250) based on the temperature information; and changing at least one of a heating setting of the at least one heating component ( 120a, 120b, 120c, 120d ) in each zone of the plurality of zones ( 250 ), independently of each other, and a flow rate of the process fluid.

12. The method of claim 11, further comprising receiving, from at least one thermocouple ( 230 ), data including a temperature of the process fluid outside the electric furnace ( 210 ).

13. The method of claim 12, further comprising: comparing the temperature information for each zone of the plurality of zones ( 250 ) and the data from the at least one thermocouple ( 230 ); anddetecting that at lea st one of a temperature of the process fluid in an inlet part ( 211 ) of the electric furnace ( 210 ), a temperature of the process fluid in an outlet part ( 212 ) of the electric furnace ( 210 ), and atemperature of at least one zone of the plurality of zones (250) is not within a respective predetermined temperature range.

14. The method of claim 13, further comprising:upon detecting that a temperature of a first zone ( 251 ) is higher than the predetermined temperature range for the first zone ( 251 ), reducing the power supply to the at least one heating component ( 120a, 120b, 120c, 120d) in the first zone (251); andincreasing or maintaining the power supply to the at least one heating component ( 120a, 120b, 120c, 120d ) in a second zone ( 252 ) adjacent to the first zone (251).

15. Use of a thermal imaging camera ( 240 ) for controlling a radiative heating system in an electric furnace ( 210 ), the use comprising:positioning the thermal imaging camera ( 240 ) outside of the electric furnace ( 210 );receiving thermal radiation from a plurality of zones (250) in the electric furnace (210) using the thermal imaging camera (240), wherein each zone of the plurality of zones (250) is defined by a respective section of a process coil (110) arranged with at least one heating component (120a, 120b, 120c, 120d) of the radiative heating system;generating temperature information for each zone of the plurality of zones ( 250 ) based on the received thermal radiation; andcontrolling the radiative heating system based on the generated temperature information.

16. The use of claim 15, wherein controlling the radiative heating system comprises independently adjusting at least one of a heating setting of the at least one heating component (120a, 120b, 120c, 120d) in each zone of theplurality of zones ( 250 ) and a flow rate of a process fluid in the process coil (110).

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