Patent Application
20240019131
Industrial ovens generate a large amount of exhaust gases as byproducts of combustion and these exhaust gases are removed via exhaust fans and other systems. The exhaust gases may also include gases produced by the items being fired. The removal of these exhaust gases is necessary to improve the safety of the oven and reduce the likelihood of explosions or secondary combustion of the gases. In many jurisdictions, the exhaust system's capability and exhaust rate (amount of exhaust gas removed per unit of time) is regulated based on the maximum burn rate of the oven. Exhaust systems can increase the cost of operating the oven however, as removing the exhaust gases results in the removal of thermal energy from the oven. Traditionally, exhaust fans operate at a fixed speed, maintaining the same exhaust rate, even if the oven burner is at a level below the maximum burn rate. This results in the unnecessary loss of thermal energy as the exhaust fan is operating at a higher rate than is required according to the regulation.
The following is a brief summary of subject matter that is described in greater detail herein. This summary is not intended to be limiting as to the scope of the claims.
Various embodiments described herein provide for a variable exhaust oven that includes a flame safety controller can be configured to receive an input signal from a temperature controller. The input signal specifies a temperature within the variable exhaust oven. Moreover, a burn rate of a burner of the variable exhaust oven can be controlled based on the temperature within the variable exhaust oven. The burn rate of the burner can be controlled by a first control signal. For example, the first control signal can be transmitted by the flame safety controller. According to another example, the first control signal can be transmitted by the temperature controller. The flame safety controller can also be configured to control an exhaust rate of an exhaust fan of the variable exhaust oven based on the burn rate of the burner. The exhaust rate of the exhaust fan can be controlled by a second control signal transmitted by the flame safety controller.
In another embodiment, a method to control a variable exhaust oven includes receiving, at a flame safety controller, an input signal from a temperature controller, where the input signal specifies a temperature within the variable exhaust oven. A burn rate of a burner of the variable exhaust oven can be controlled based on the temperature within the variable exhaust oven. The burn rate of the burner can be controlled by a first control signal. The first control signal can be transmitted by the flame safety controller or the temperature controller, for example. The method also includes controlling an exhaust rate of an exhaust fan of the variable exhaust oven based on the burn rate of the burner. The exhaust rate of the exhaust fan can be controlled by a second control signal transmitted by the flame safety controller.
In another embodiment, a variable exhaust oven includes a burner, a fuel supply valve, an exhaust fan, a temperature controller, and a flame safety controller. The fuel supply valve can be configured to control a flow of fuel supplied to the burner. The exhaust fan can be configured to remove exhaust air from the variable exhaust oven, where the exhaust fan has a plurality of exhaust fan settings corresponding to different exhaust rates (e.g., fan speeds, damper settings, etc.). Further, the temperature controller can be configured to transmit an input signal that specifies a temperature within the variable exhaust oven. Moreover, the flame safety controller can be configured to receive the input signal from the temperature controller, transmit a first control signal to the fuel supply valve to control a burn rate of the burner, and transmit a second control signal to the exhaust fan to control an exhaust rate of the exhaust fan. The burn rate can be controlled based on the temperature within the variable exhaust oven. Further, the exhaust rate can be controlled based on the burn rate of the burner.
The above summary presents a simplified summary to provide a basic understanding of some aspects of the systems and/or methods discussed herein. This summary is not an extensive overview of the systems and/or methods discussed herein. It is not intended to identify key/critical elements or to delineate the scope of such systems and/or methods. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
Various technologies pertaining to a variable exhaust oven are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form to facilitate describing one or more aspects. Further, it is to be understood that functionality that is described as being carried out by certain system components may be performed by multiple components. Similarly, for instance, a component may be configured to perform functionality that is described as being carried out by multiple components.
Moreover, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from the context, the phrase “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X employs A or B” is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from the context to be directed to a singular form.
Further, as used herein, the terms “component” and “system” are intended to encompass computer-readable data storage that is configured with computer-executable instructions that cause certain functionality to be performed when executed by a processor. The computer-executable instructions may include a routine, a function, or the like. It is also to be understood that a component or system may be localized on a single device or distributed across several devices. Additionally, as used herein, the term “exemplary” is intended to mean serving as an illustration or example of something and is not intended to indicate a preference.
Various embodiments disclosed herein provide for a variable exhaust oven that can modify an exhaust rate of an exhaust fan of the oven based on the firing rate or burn rate of a burner of the oven while still complying with safety regulations. By reducing the exhaust rate of the variable exhaust oven when the burn rate decreases, the variable exhaust oven can save costs by reducing the thermal energy lost due to unnecessary removal of air from the oven, and can lower electrical costs by operating the exhaust fan at a lower speed. The burn rate of the burner can be controlled based on a temperature within the variable exhaust oven. Moreover, a flame safety controller of the variable exhaust oven can control the exhaust rate of the exhaust fan based on the burn rate of the burner. As the burn rate decreases, the exhaust rate of the exhaust system can also be reduced by adjusting exhaust fan speeds or damper settings.
Turning now to
It is to be appreciated that the variable exhaust oven 100 could be any industrial or commercial heating apparatus that burns a fuel source and that has an active exhaust system. The variable exhaust oven 100 can be a gas or fuel-fired oven or furnace. The variable exhaust oven 100 could be any heating apparatus that provides heat for an industrial or commercial process. Types of industrial ovens include batch ovens, continuous process ovens, and conveyor ovens. Industrial furnaces are used in applications such as chemical reactions, oil refining, metals processing, and glasswork. The variable exhaust oven 100 could also be a kiln which is a thermally insulated chamber that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. The exhaust gases 110 could be the byproducts of the combustion of the fuel source, or could be the byproducts of the articles or product being heated or treated inside the variable exhaust oven 100, such as articles offgassing, or gases created from chemical reactions within the variable exhaust oven 100.
The fuel could be natural gas, or any other liquid or gaseous fuel source that can create heat when combusted. In an embodiment, the fuel can flow or be pumped into the burner 104 and is burnt with intake air 108 provided either passively or actively via an air blower. There can be more than one burner in a particular oven which can be arranged in cells which heat a particular set of tubes. Burners can also be floor mounted, wall-mounted or roof-mounted depending on design. In some embodiments, the exhaust gases 110 can be piped directly to the exhaust fan 106 without entering the main chamber 102 and the main chamber 102 could be heated by radiation from the pipes. In other embodiments, the exhaust gases 110 can enter a main chamber 102 of the variable exhaust oven 100 and the exhaust fan 106 can remove both the exhaust gases and any other gases from the chamber 102 of the variable exhaust oven 100.
In an embodiment, the intake air 108 can be cold air that is either passively supplied or supplied via an air pump. The air intake can include primary air that is first introduced to the burner 104, secondary air that is added to supplement the primary air, etc. In some embodiments, the intake air 108 can be premixed with the fuel to improve combustion before being provided to the burner 104. According to an illustration, the intake air 108 can include combustion air and makeup air. The combustion air can be mixed with fuel to facilitate combustion of the fuel (e.g., a ratio of parts of air to fuel can be used for combustion). For instance, a flow rate of the combustion air can be varied with firing of the burner 104. A rate of flow of the makeup air can be dependent on the operation of the exhaust fan 106 (e.g., the makeup air replaces the exhaust gases 110 removed from the variable exhaust oven 100).
Turning now to
Turning now to
The flame safety controller 304 can be configured to receive the input signal that specifies the temperature within the variable exhaust oven 100. A burn rate of the burner 104 can be controlled based on the temperature within the variable exhaust oven 100 (e.g., within the chamber 102). The burn rate of the burner 104 can be controlled by a first control signal. According to an example, the flame safety controller 304 can transmit the first control signal. Pursuant to another example, the temperature controller 302 can transmit the first control signal.
The first control signal, for instance, can adjust the fuel supply, the air supply, and other inputs to the burner 104. As shown in the depicted example of
The flame safety controller 304 can include a PID (proportional-integral-derivative) controller that uses a closed loop logic system to provide control signal(s). A PID controller continuously calculates an error value as the difference between a desired setpoint (SP) and a measured process variable (PV) and applies a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively). In practical terms, the PID controller automatically applies an accurate and responsive correction to a control function, in this case the fuel supply and/or air supply.
According to various embodiments, the temperature controller 302 can include a PID controller that sets the burn rate of the burner 104. Pursuant to an example, the input signal transmitted from the temperature controller 302 to the flame safety controller 304 can further specify the burn rate set by the temperature controller 302. Further following this example, the flame safety controller 304 can transmit the first control signal that controls the burn rate as set by the temperature controller 302. In accordance with this example, output from the temperature controller 302 (namely, a signal controlling the burn rate of the burner 104) can flow through the flame safety controller 304.
Pursuant to a differing example where the temperature controller 302 includes a PID controller that sets the burn rate of the burner 104, the temperature controller 302 can alternatively transmit the first control signal without having the output flow through the flame safety controller 304.
Moreover, the flame safety controller 304 can be configured to control an exhaust rate of the exhaust fan 106 of the variable exhaust oven 100 based on the burn rate of the burner 104. The exhaust rate of the exhaust fan 106 can be controlled by a second control signal transmitted by the flame safety controller 304. As described below in more detail, the second control signal can control a speed of the exhaust fan 106, cause adjustment of a damper of the exhaust fan 106, a combination thereof, and so forth. Thus, the flame safety controller 304 can send the second control signal to adjust the exhaust rate or fan speed of the variable exhaust fan 106.
According to various embodiments, it is contemplated that the flame safety controller 304 can also be communicably coupled to a gas flow meter that can measure the absolute or relative flow of fuel and/or air to the burner 104 through the fuel supply line 306. Thus, the flame safety controller 304 can receive a second input signal from the gas flow meter that specifies the gas flow rate to the burner 104; accordingly, the exhaust rate of the exhaust fan 106 can further be controlled by the flame safety controller 304 based on the second input signal. According to another example, a differing device (e.g., a differing controller, a programmable logic controller (PLC), etc.) can receive the second input signal from the gas flow meter that specifies the gas flow rate to the burner 104; the exhaust rate of the exhaust fan 106 can be further controlled by the flame safety controller 304 and/or the differing device based on the second input signal. The gas flow meter could be located inside the fuel supply line 306 or could be mounted external to the fuel supply line 306. The gas flow meter can be an example of a flow sensor that can further be classified into one of two groups: contact and non-contact flow sensors. Contact flow sensors are used in applications where the liquid or gas measured is not expected to become clogged in the pipe when it comes into contact with the sensor's moving parts. In contrast, non-contact flow sensors have no moving parts, and they are generally used when the liquid or gas being monitored would be otherwise contaminated or physically altered by coming into contact with moving parts.
The two most common types of contact flow sensors are vortex and mechanical flow sensors. Vortex flow sensors are comprised of a small latch (known as the “buff body”) that flexes back and forward when coming into contact with a flowing liquid or gas. The differences in pressure (i.e., the vortices) generated by the latch are measured to determine the flow rate. Mechanical flow sensors use propellers that spin at a rate that is directly proportional to the flow rate. Mechanical flow sensors can also be controlled to cause the flow rate to increase or decrease.
Ultrasonic flow sensors are the most popular type of non-contact flow sensor. Ultrasonic flow sensors send pulses of high frequency sound across the flowing liquid or gas medium. These sensors measure the time between the emission of the sound and its contact with the sensor's receiver to determine the flow rate of the gas or liquid.
In an embodiment, the flame safety controller 304 can receive an indication of the flow rate as determined by the sensor so that the exhaust rate or fan speed of the variable exhaust fan 106 can be adjusted. The exhaust rate or the fan speed can be controlled by the flame safety controller 304 based on the flow rate (e.g., the flame safety controller 304 need not receive the input signal from the temperature controller 302 specifying the temperature within the variable exhaust oven 100) or a combination of the temperature within the variable exhaust oven 100 and the flow rate (e.g., the flame safety controller 304 can control the exhaust fan 106 based on the input received from the temperature controller 302 and the second input received from the gas flow meter).
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The flame safety controller 304 can transmit a control signal (e.g., the second control signal) to a variable frequency drive 412 of the variable exhaust fan 106 to control the fan speed. Thus, the variable frequency drive 412 can be controlled based on the control signal to control the exhaust rate of the exhaust fan 106. The flame safety controller 304 can additionally or alternatively transmit a control signal (e.g., the second control signal) to a damper motor 414 of the exhaust fan 106 to adjust the exhaust rate of the variable exhaust oven 100 (e.g., the exhaust rate of the exhaust fan 106) by adjusting the air opening which can regulate the amount of exhaust allowed to escape.
In an embodiment, flame safety controller 304 can include a logic circuit 402 that can determine what the overall exhaust rate of the variable exhaust oven 100 should be based on the burn rate of the burner 104. While being described as being included as part of the flame safety controller 304 in various embodiments, it is contemplated that a differing controller (e.g., a PLC) separate from and in communication with the flame safety controller 304 can additionally or alternatively include the logic circuit 402. Thus, the examples set forth below can be extended to scenarios where the logic circuit 402 is part of a differing, separate controller.
In some embodiments, the logic circuit 402 can include a memory 406 that stores one or more computer-executable programs and a processor 404 that can execute the computer-executable programs to cause the processor 404 to perform one or more actions. The memory 406 can also store information relating to the safety standards and regulations pertaining to variable exhaust ovens and furnaces. In at least one embodiment, the memory 406 can store information relating the safety standards as described in NFPA (National Fire Protection Association) 86 which defines the exhaust rate for a variable exhaust oven based on the number of BTUs (British Thermal Units) that the burner 104 is capable of generating. Based on the information about the burn rate, the logic circuit 402 can determine what the exhaust rate of the variable exhaust oven 100 should be in order to comply with the regulations. By way of example, the memory 406 can include a look up table that indicates exhaust rates corresponding to respective burn rates. Following this example, the logic circuit 402 can identify, from the look up table, an exhaust rate that corresponds to the received burn rate from the burner controller 308. Pursuant to an illustration, a relationship between the gas flow rate and the exhaust rate (e.g., the safety ventilation rate) can be that the exhaust rate is 0.000183 times the gas flow rate (e.g., Exhaust rate=0.000183 * gas flow rate (in BTUs/hr)); however, the claimed subject matter is not so limited. According to another example, the memory 406 can store a program (executable by the processor 404) configured to compute the exhaust rate of the variable exhaust oven 100 based on the exhaust rate. Pursuant to an illustration, it is contemplated that the program can compute the exhaust rate utilizing the following formula: Exhaust rate=0.000183 * gas flow rate (in BTUs/hr).
Once the logic circuit 402 determines the exhaust rate for the variable exhaust oven 100, a VFD (Variable Frequency Drive) component 408 can send a control signal to a VFD 412 of the variable exhaust fan 106. A variable frequency drive is a type of motor drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input current and/or voltage. In an embodiment, the VFD component 408 can control the speed of the variable exhaust fan 106 by sending a control signal to the VFD 412, where the control signal can facilitate the VFD changing the fan speed. A higher fan speed of the exhaust fan 106 as controlled by the VFD component 408 can thus lead to a higher exhaust rate.
The VFD component 408 can determine the fan speed of the variable exhaust fan 106 based on information about the variable exhaust fan 106. For example, the VFD component 408 can use a look up table that contains information about the exhaust rate of the variable exhaust fan at a plurality of different fan speeds, and then send a control signal to the VFD 412. In an embodiment, there can be a definite number of fan speed settings that the VFD component 408 can select from, where the VFD component 408 selects the fan speed setting that will result in an exhaust rate just above the exhaust rate as determined by the burn rate. In other embodiments, the VFD component 408 can select a frequency for the control signal to the VFD 412 that will result in a fan speed and exhaust rate that is a set percentage above the regulated exhaust rate for a given burn rate.
In an embodiment, a damper component 410 can provide a control signal to a damper motor 414 of the exhaust fan 106 to adjust a damper setting to control the exhaust rate of the variable exhaust fan 106. The damper can control the amount of air that is allowed to pass through the variable exhaust fan 106. As an example, as seen in the embodiments in
In an embodiment, the damper component 410 can control the exhaust rate of the variable exhaust fan 106 alone, without adjusting the fan speed via the VFD component 408. Similarly in some embodiments, the VFD component 408 can adjust the exhaust rate by sending the control signal to the VFD 412 to change the fan speed while the damper is fixed. In other embodiments, the fan speed and the damper settings can both be adjusted simultaneously or concurrently to achieve the desired exhaust rate.
Moreover, the acts described herein may be computer-executable instructions that can be implemented by one or more processors and/or stored on a computer-readable medium or media. The computer-executable instructions can include a routine, a sub-routine, programs, a thread of execution, and/or the like. Still further, results of acts of the methodologies can be stored in a computer-readable medium, displayed on a display device, and/or the like.
The methodology 600 begins at 602, and at 604, the method can include the step of receiving, at a flame safety controller, an input signal from a temperature controller. The input signal can specify a temperature within the variable exhaust oven. The temperature controller, for instance, can detect the temperature within the variable exhaust oven based on a temperature signal received by the temperature controller from a thermocouple within the variable exhaust oven. a burn rate of a burner of the variable exhaust oven can be controlled based on the temperature within the variable exhaust oven. The burn rate of the burner can be controlled by a first control signal. The first control signal, for example, can be transmitted by the flame safety controller. Pursuant to another example, the first control signal can be transmitted by the temperature controller. For instance, the first control signal can be transmitted to a fuel supply valve, where the first control signal controls a fuel supply valve setting of the fuel supply valve (e.g., to control a flow of fuel supplied to the burner).
At 606, the method can include controlling an exhaust rate of an exhaust fan of the variable exhaust oven based on the burn rate of the burner. The exhaust rate of the exhaust fan can be controlled by a second control signal transmitted by the flame safety controller. For instance, the second control signal can be transmitted to a variable frequency drive such that the variable frequency drive is controlled based on the second control signal to control the exhaust rate of the exhaust fan (e.g., the second control signal can control a fan speed). Additionally or alternatively, the second control signal can control an adjustment of a damper of the exhaust fan to control the exhaust rate of the exhaust fan (e.g., the second control signal can control a damper motor to adjust a damper of the variable exhaust fan, changing the air flow allowed to pass through the variable exhaust fan). At 610, the method can end.
Referring now to
The computing device 700 additionally includes a data store 708 that is accessible by the processor 702 by way of the system bus 706. The data store 708 may include executable instructions, etc. The computing device 700 also includes an input interface 710 that allows external devices to communicate with the computing device 700. For instance, the input interface 710 may be used to receive instructions from an external computer device, from a user, etc. The computing device 700 also includes an output interface 712 that interfaces the computing device 700 with one or more external devices. For example, the computing device 700 may display text, images, etc., by way of the output interface 712.
It is contemplated that the external devices that communicate with the computing device 700 via the input interface 710 and the output interface 712 can be included in an environment that provides substantially any type of user interface with which a user can interact. Examples of user interface types include graphical user interfaces, natural user interfaces, and so forth. For instance, a graphical user interface may accept input from a user employing input device(s) such as a keyboard, mouse, remote control, or the like and provide output on an output device such as a display. Further, a natural user interface may enable a user to interact with the computing device 700 in a manner free from constraints imposed by input device such as keyboards, mice, remote controls, and the like. Rather, a natural user interface can rely on speech recognition, touch and stylus recognition, gesture recognition both on screen and adjacent to the screen, air gestures, head and eye tracking, voice and speech, vision, touch, gestures, machine intelligence, and so forth.
Additionally, while illustrated as a single system, it is to be understood that the computing device 700 may be a distributed system. Thus, for instance, several devices may be in communication by way of a network connection and may collectively perform tasks described as being performed by the computing device 700.
Various functions described herein can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer-readable storage media. A computer-readable storage media can be any available storage media that can be accessed by a computer. By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc (BD), where disks usually reproduce data magnetically and discs usually reproduce data optically with lasers. Further, a propagated signal is not included within the scope of computer-readable storage media. Computer-readable media also includes communication media including any medium that facilitates transfer of a computer program from one place to another. A connection, for instance, can be a communication medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio and microwave are included in the definition of communication medium. Combinations of the above should also be included within the scope of computer-readable media.
Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.
What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable modification and alteration of the above devices or methodologies for purposes of describing the aforementioned aspects, but one of ordinary skill in the art can recognize that many further modifications and permutations of various aspects are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
