US20240053006A1

US20240053006A1 - Compensator for controlling airflow in fired heater

Info

Publication number: US20240053006A1
Application number: US18/446,663
Authority: US
Inventors: Walter F. GULL
Original assignee: Birwelco Usa Inc
Current assignee: Birwelco Usa Inc
Priority date: 2022-08-10
Filing date: 2023-08-09
Publication date: 2024-02-15

Abstract

A compensator, system, and method of controlling airflow through a fired heater or furnace. The compensator has a stationary plate disposed across the burner intake and a movable plate disposed adjacent to the stationary plate that is movable between first and second lateral positions to control the airflow through the intake. In the first lateral position, second openings of the movable plate are at least partially aligned with first openings of the stationary plate, thereby defining a first level of airflow through the intake. In the second lateral position, the second openings of the movable plate are at least partially misaligned with the first openings of the stationary plate, thereby defining a second level of airflow through the intake. The airflow through the intake at the second level is less than the air flow through the intake at the first level.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 63/396,684, entitled Compensator System For Automated Control Of Combustion Air In Induced-Draft Or Natural-Draft Fired Heater, filed Aug. 10, 2022, the entire subject matter of which is herein incorporated by reference.

FIELD OF THE DISCLOSURE

The subject matter of the present disclosure relates generally to an airflow compensator system for an industrial, direct-fired heater or furnace, namely an induced-draft or a natural-draft fired heater.

BACKGROUND OF THE DISCLOSURE

Industrial-fired heaters are used in many processes related to refining, petrochemical, and other industries. For example, industrial direct-fired heaters are used in oil refining processes (heaters) and in chemical and petrochemical processes (furnaces) to induce separation of, or chemical reactions, within organic materials.
The design of such fired heaters typically conform to the American Petroleum Institute (API) 560 standard. The API 560 Standard specifies the requirements and recommendations for fired heaters within refineries covering such things as the design, materials, fabrication, inspection, testing, preparation for shipment, and erection of fired heaters, air preheaters (APHs), fans, and burners for general refinery service. The API 560 standard is used internationally throughout industry and often serves as a baseline for private oil company fired heater and furnace specifications.
Such fired heater typically have a radiant section, a radiant coil, burners, and a flue gas stack. The fired heater can incorporate a convection section with a convection coil and can use forced draft and/or induced draft fans or combustion air preheating. The fired heater is designed to transfer a defined amount of heat/energy to the coils at a certain rate, based on the volume and rate of organic material running through the coils all at a specified efficiency. Depending on the intended process, for example, the fired heater can operate in the temperature range from 400 2° C. to over 1000 2° C.
FIG. 1 shows an example of a fired heater 10, which includes a burner section 12, a radiant section or firebox 14, a convection section 16, and a stack 18. The burners 20 are often arranged in rows at the floor (hearth) 17 of the firebox 14 so the flames from the burners 20 can produce radiant heat in the firebox 14. The radiant heat in the firebox 14 is in turn transferred to organic materials conveyed in a continuous path through radiant tube coils 30 that line the interior walls of the firebox 14. The walls of the firebox 14 can have ceramic fiber insulation or castable refractory lining 15, which can reduce heat loss, can radiate heat back toward the back (shadowed) side of the tube coils 30, and can keep the temperatures of the coils 30 as designed. For efficiency, the convection section 16 allows heat to be transferred to the conveyed organics in convection coils 40 through the process of convective heat transfer as heated flue gases rise out of the firebox 14, through the convection section 16, and up and out the flue gas stack 18.
The quantity and location of the burners 20 within the radiant firebox 14 can vary. Nevertheless, the burners 20 are typically organized in rows, columns, and the like in the floor (hearth), walls, or roof (arch). The fired heater 10 must carefully control the burning of the fuels that generate the heat needed for the process during operation. This control is achieved by regulating the amount of air available within the radiant firebox 14 of the fired heater 10, ensuring the correct amount of air is available for the safe combustion of the fuel introduced into the radiant firebox 14 through the burners 20. Any air introduced into the radiant firebox 14 through the burners 20 that is not needed for the safe combustion of the fuel is referred to as excess air.
As the air used for the combustion process is introduced into the radiant firebox 14 through the burners 20, the volume and rate of the combustion airflow is dictated by the draft (negative pressure) within the radiant firebox 14. For a natural-draft fired heater, this draft is generated by the buoyancy effect of the hot flue gas within the fired heater 10 and its stack 18. A damper 19, typically located in the stack 18, is used to regulate this buoyancy effect. For an induced-draft fired heater, an induced draft fan (not shown) produces the draft (negative pressure) within the heater radiant firebox 14. The draft for the fan is regulated by the use of a damper 19 (or similar) or by varying the speed of the fan itself. The amount of combustion air flow through the fired heater 10 can be further controlled at each individual burner 20 by using a secondary damper or a burner register 22 at the burner's intake 21.
The heater 10 should not be operated in a condition in which there is not enough air available in the firebox 14 to ensure the complete burning of the fuel introduced. For this reason, operators typically operate the fired heater 10 with levels of excess air, which can increase pollution and will reduce the efficiency of the heater's operation.
Overall, the operational rate of the fired heater 10 can vary as does the amount of heating produced by the burner fuel used. Therefore, it is often not possible to accurately and reliably control the amount of combustion air entering the firebox 14 through the burners 20 using just a stack damper 19 or an induced fan damper. This is especially true when fine control of the excess air is to be maintained to improve the efficiency of the fired heater 10 and reduce pollution generated.
Finer control of any excess air in the heater 10 may require the accurate use of the burner registers 22. The burner registers 22 used individually on each burner 20 typically have a louver design. Each burner register 22 is operated manually and independently to control the air for its associated burner 20. As a result, adjusting the burner register 22 can be extremely difficult to automate. Attempts to automate the operation of the burner register 22 are compounded even further with the increase in the number of burners 20 used in a fired heater design. With the ever-changing needs in the volume of combustion air needed during operations of the fired heater 10, it is impractical for an operator to manually fine-tune the burner registers 22 to control the amount of combustion air that enters through the burners 20 into the radiant firebox 14.
Attempts in the past to automatically control the amount of combustion air entering through the burner registers 22 have used rotational arrangements. In one rotational arrangement, a rotating jackshaft uses a rotary actuator and a system of linkages that connect the jackshaft to multiple burner registers 22. Rotation of the jackshaft can open and close the burner registers 22 to control the airflow. The relationship of every degree of rotation of the jackshaft with respect to the flow of the air is not linear. This can require more rotation to achieve the same increase in airflow, complicating the responsiveness of the automation.
The rotating jackshaft arrangement also has many other issues. The burner registers 22 tend to bind, and rotational joints tend to wear out, causing the entire system to lock up and bind, often causing any longer linkages to flex and not fully rotate under the load. Adjusting/calibrating the system is difficult, if not impossible, which can lead to long-term performance-related issues for the burners 20 and the heater 10 overall. In addition, it is difficult to take a given burner 20 out of service and disconnect/reconnect the rotating jackshaft in such arrangements.
In another rotational arrangement, individual rotational actuators can be mounted on each of the registers 22 for the burners 20. This rotational arrangement is rarely done, especially when there are many burners 20 in the fired heater 10. The cost of installation is high, and there may be expensive long-term maintenance costs. Again, the relationship of every degree of rotation of the burner register 22 with respect to the flow of the air is not linear. This can require more rotation to achieve the same increase in airflow, complicating the responsiveness of the automation. A primary concern of this arrangement is the resulting complexity of the controls as a result. As each rotational actuator really functions as an independent system, failed control at any of the registers 22 can produce isolated areas within the firebox 14 that do not have sufficient air for combustion from an operational perspective.
In some implementations, multiple burners 20 can be attached to a common section of ductwork, and a single automated damper can be used with the common ductwork to control the combustion air to those respective burners 20. This arrangement does not work well because it can only provide ideal control for a specific operational firing rate. Increasing or decreasing the firing rate of the fired heater 10 will change the combustion air distribution to the different burners 20 attached to the common ductwork, some getting more and some getting less. From an operational perspective, this could potentially create a situation in which isolated areas within the firebox 14 do not have sufficient air for combustion.
As opposed to the typical louvered configuration for a burner register, another type of burner register has an air inlet that includes a perforated plate running a full circumference around the body of the burner's inlet. A back plate can be slid up and down relative to the perforated plate, effectively blocking a portion of the holes and reducing the amount of air that can enter the burner. A rotational jackshaft system connects to the burner registers to provide automated control of multiple burners. Effectively, the rotational jackshaft system is a rotary actuator with a shaft that rotates. A cam immediately under the burner allows for the back plate to be raised or lowered. This design approach is used to promote an even, 360-degree entrance of the air into the burner to improve combustion. Again, the design is based on a rotational arrangement and can suffer drawbacks as noted above.

SUMMARY

The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
Accordingly, the present disclosure provides a compensator for a burner of a fired heater or furnace. The burner has an intake for airflow. The compensator comprises a stationary plate disposed across the intake and across a direction of the airflow through the intake. The stationary plate includes one or more first openings. A movable plate is disposed adjacent to the stationary plate and includes one or more second openings. the movable plate being movable between first and second lateral positions with respect to the stationary plate to control the airflow through the intake, wherein in the first lateral position, the one or more second openings of the movable plate are at least partially aligned with the one or more first openings of the stationary plate, thereby defining a first level of airflow through the intake, wherein in the second lateral position, the one or more second openings of the movable plate are at least partially misaligned with the one or more first openings of the stationary plate, thereby defining a second level of airflow through the intake, and wherein the airflow through the intake at the second level is less than the air flow through the intake at the first level.
In certain embodiments, in the first lateral position, the one or more second openings are substantially aligned with the one or more first openings such that the first level is a maximum amount of airflow allowed through the intake, and in the second lateral position, the one or more second openings are substantially misaligned with the one or more first openings such that the second level is a minimum amount of airflow allowed through the intake; the first and second openings are configured to vary the airflow for the intake in a linear relationship between the first and second levels with the movement of the movable plate between the first and second lateral positions; a movable support member is movable in a lateral direction relative to the stationary plate that is generally transverse to the direction of the airflow through the intake, the movable plate is releasably coupled to the movable support member, and the movable support member is configured to move the movable plate with respect to the stationary plate between the first and second lateral positions; the movable support member is a slidable elongated bar; an actuator is configured to slide the bar with respect to the stationary plate; a coupling removably connects the movable plate to the bar, and the coupling comprises a mount disposed on the movable plate, a flange disposed on the bar, and a locking pin removably connecting the flange to the mount; and/or a housing configured to affix to the burner and having an opening, a first end of the housing communicating with the intake, and a second end of the housing having the stationary plate disposed across the opening.
In other embodiments, a breaker plate is disposed adjacent to the movable plate and is configured to interrupt the airflow to the first and second openings to address interference due to wind directions; a friction reducer supporting the movable plate on the compensator; the friction reducer comprises a support plate, track, or guide disposed between a first surface of the movable plate and a second surface of the compensator; at least one sensor is configured to measure one or more characteristics associated with operation of the burner, and a controller is in communication with the sensor and is configured to control the moveable plate based on the measured characteristic to adjust the airflow through the intake; the sensor comprises one or more of an oxygen sensor, a fuel gas BTU sensor, and a calorimeter; and/or a curb is disposed between the movable plate and the stationary plate on each side of the one or more first openings, the curbs are configured to reduce leakage of the air from the sides between the plates.
In some embodiments, the one or more first openings comprise two first openings that have a first width in the lateral direction, the two first openings are separated by a first separation at least as great as the first width, and wherein the one or more second openings comprise two second openings that have a second width in the lateral direction, the two second openings separated by a second separation at least as great as the second width; the first width is substantially equal to the second width; wherein the first separation is substantially equal to the second separation; a first shape of the first openings is the same as a second shape of the second openings; and/or the one or more first and second openings each comprise a quadrilateral having sides of unequal length, vertical ones of the sides being parallel to one another, a lateral one of the sides being orthogonal to the vertical sides, another lateral one of the sides being oblique to the vertical sides.
The present disclosure may also provide a compensator system for a fired heater or furnace that has a plurality of burners. Each burner has an intake for airflow. The compensator system comprises at least one movable support member that is movable laterally relative to the intakes in a direction generally transverse to a direction of the airflow. A plurality of stationary plates are disposed across the intakes of the burners, respectively, and includes one or more first openings. A plurality of movable plates are disposed adjacent to the plurality of stationary plates, respectively, and include one or more second openings. Each movable plate is releasably coupled to the movable support member. A controller is configured to move each of the plurality of movable plates between first and second lateral positions via movement of the moving support member to control the airflow through the intake of each burner, respectively. In the first lateral position, the one or more second openings of each movable plate are at least partially aligned with the one or more first openings of a respective stationary plate, thereby defining a first level of airflow through the intake of each burner, respectively. In the second lateral position, the one or more second openings of each movable plate are at least partially misaligned with the one or more first openings of the respective stationary plate, thereby defining a second level of airflow through the intake of each burner, respectively, and wherein the airflow at the second level is less than the air flow at the first level.
In some embodiments, the controller is configured to move each of the movable plates between the first and second lateral positions at substantially the same time via the movable support member; the controller automatically controls the airflow between the first and second levels; an actuator coupled to the movable support member is configured to slide the movable support member with respect to the stationary plates; the movable support member is an elongated bar; and/or a bearing is configured to support the bar to a portion of the fired heater.
In one embodiment, a method of controlling airflow through a fired heater or furnace comprises the step of adjusting the airflow using the compensator system.
In another embodiment, a fired heater or furnace comprises a radiant firebox that has a floor, walls, a roof, and a stack; a plurality of burners disposed in the firebox at the floor, walls, or roof, and each of the burners has an intake for airflow; and a compensator according to the present disclosure is disposed at the intake of one or more of the burners.
In other embodiments, the burners are arranged in at least two rows; and at least two movable support members are each arranged on one of the at least two rows; at least one actuator coupled to the at least two movable support members and are configured to move the at least two movable support members along the rows; each movable support member is an elongated bar; and/or a controller is configured to automatically adjust the airflow through one or more of the burners via one or more of the compensators between the first and second levels.
This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide an overview or framework to understand the nature and character of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated in and constitute a part of this specification. It is to be understood that the drawings illustrate only some examples of the disclosure and other examples or combinations of various examples that are not specifically illustrated in the figures may still fall within the scope of this disclosure. Examples will now be described with additional detail through the use of the drawings, in which:

FIG. 1 illustrates an example of a fired heater according to the prior art.

FIG. 2 illustrates a plan view of multiple burners for a fired heater having a compensator system according to the present disclosure.

FIGS. 3A-3C illustrate schematic views of a compensator assembly of the present disclosure in different states of operation.

FIG. 4 illustrates a front elevational view of compensator assemblies of the disclosed system arranged at intakes for burners of a fired heater.

FIG. 5A illustrates a front elevational view of a compensator assembly according to an embodiment of the present disclosure, showing the compensator assembly in more detail with a sliding plate in a fully closed position.

FIG. 5B illustrates a side elevational view of the compensator assembly in FIG. 5A, showing the compensator assembly assembled.

FIG. 5C illustrates another side elevational view of disassembled components of the compensator assembly of FIG. 5A.

FIG. 6 illustrates an isolated plan view of a coupling between a support member and a movable plate of the compensator assembly according to the present disclosure.

FIG. 7A schematically illustrates a shape for an opening in the compensator assembly according to an embodiment of the present disclosure.

FIG. 7B schematically illustrates openings in the compensator assembly in an intermediate state of alignment.

FIG. 8 is a graph that shows a burner's firing rate relative to an opening percentage for a two-blade air register as compared to the compensator assembly of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure relates to a compensator, compensator system, and method of use for controlling the airflow through a fired heater or furnace. The system includes one or more compensators for the burners of the fired heater. Each compensator generally comprises a stationary plate disposed across the intake of a burner and the direction of the airflow through the intake; and a movable plate that is disposed adjacent to the stationary plate. The stationary plate has one or more first openings and the movable plate includes one or more second openings. The movable plate is movable between first and second lateral positions with respect to the stationary plate. In the first lateral position, the one or more second openings of the movable plate are at least partially aligned with the one or more first openings to control the airflow through the intake to a first level, and in the second lateral position, the one or more second openings are at least partially misaligned with the one or more first openings to control the airflow through the intake to a second level, wherein the airflow at the second level is less than the air flow at the first level. The compensator system has at least one movable support member associated with the moveable plates of each compensator. Each of the support members are movable laterally relative to the burner intakes in a direction generally transverse to a direction of the airflow. A controller is configured to move the movable plates between first and second lateral positions via movement of the moving support member to adjust and fine tune the amount of airflow through the burner intakes. The controller is configured to automate the compensator system. As such, the present disclosure accurately and reliably controls the amount of combustion air entering the firebox 14 through the burners 20 and reduces excess air.
Referring to the figures, the present disclosure relates to a compensator system 100 for controlling the amount of combustion air introduced through each burner 20 for operating the heater 10 at reduced levels of excess air. The compensator system 100 is designed to allow the fired heater 10 to safely operate with the least amount of excess air, resulting in significant fuel savings and the generation of less pollution. This compensator system 100 will allow fired heaters to achieve a level of performance never even thought of when originally built. And the compensator system 100 can be an automated system, such as by allowing each of the compensators 50 of the compensator system 100 to operate at the same time.
FIG. 2 illustrates a plan view of multiple burners 20 for a fired heater 10 having a compensator system 100 according to the present disclosure. The plan view shows a portion of the fired heater 10 with a total quantity of thirty-six burners 20 organized in a total of 4 rows, for example. As will be appreciated, but not shown in FIG. 2 , the fired heater 10 includes a radiant firebox having a floor and a stack. The burners 20 can be installed at the floor to produce radiant heat for the firebox. In any event, the fired heater 10 can be an induced-draft fired heater, a natural-draft fired heater, or the like. The quantity, number of rows or columns, and location of the burners 20 within the radiant firebox 14 can vary, and the burners 20 can be organized in rows, columns, and the like in the floor (hearth), walls, or roof (arch) of the heater 10.
Each of the burners 20 has an intake 21 for combustion air. As noted, the intake 21 typically includes a louvered register 22 that can be rotated to adjust the airflow through the intake 21. The compensator system 100 includes one or more compensators 50 (also referred to herein as compensator assemblies) used for at least one or more of the burners' intakes 21. As shown in the example of FIG. 2 , one compensator assembly 50 can be mounted onto the intake 21 of each burner 20.
Each compensator 50 may include a housing or transition body 52 (FIG. 3A) configured to attach to the intake 21 of the respective burner 20. The housing or transition body 52 has a stationary (or back) plate 60 covering the intake 21 to control the passage of combustion air into the intake 21. In general, the stationary plate 60 can be characterized as a baffle, a wall, barrier, or the like that is designed to cover the intake 21 for the air into to the burner 20. The stationary plate 60 can have one or more openings 62 (FIGS. 3A-3C) for passage of airflow therethrough.
Each compensator 50 also has a movable (or front) plate 70 disposed adjacent to and in front of the stationary plate 60 at the intakes 21. The movable plates 70 can be characterized as sliding doors, louvers, or the like. Like the stationary plates 60, the movable plates 70 can have openings 72 (FIGS. 3A-3C) for the passage of airflow.
Couplings 80 connect the movable plates 70 to a movable support member 90 of the system 100. The movable support member 90 can be, in one example, an elongated thrust bar. The couplings 80 can be selectively connectable to the movable plates 70. To adjust the airflow into the intake 21 of each burner 20, respectively, each movable plate 70 can be moved laterally with respect to the stationary plate 60, that is between lateral positions, by sliding the corresponding movable support member 90 in a direction generally transverse to the direction of airflow into the burner intake (or in a direction of the length of the elongated 90). The selected lateral position of the moveable plate 70 can change the alignment between the openings 62, 72 in the plates 60, 70, thereby adjusting the amount of airflow that can pass through the plates 60, 70 and into the intake 21 of the respective burner 20.
For example, the movable plate 70 can be positioned laterally, i.e. in a lateral position, with respect to the position of the adjacent stationary plate 60 disposed across the intake 21 of the burner 20. In turn, the configuration/position of openings 62 in the plates 60, 70 can either increase or decrease the amount of combustion air capable of entering the burner's intake 21 during operation depending upon the alignment of the openings. The one or more elongated bars 90 are slidable relative to the burner intakes 21 using one or more actuators 110. Movement of the bars 90 in turn alters the lateral position of the movable plates 70 relative to the stationary plates 60 at the intakes 21. This positioning thereby adjusts the amount of airflow permitted into the intake 21 of the burner 20.
FIGS. 3A-3C illustrate sectional views of a compensator 50 of FIG. 2 in different states of operation. The stationary plate 60 includes one or more first openings 62 therein and the movable plate 70 includes one or more second openings 72. The movable plate 70 is coupled to the thrust bar 90 by the coupling 80 and is disposed adjacent to the stationary plate 60. Like the stationary plate 60, the movable plate 70 defines one or more second openings 72 therein. To adjust the airflow into the intake 21 of the burner 20, the movable plate 70 can be moved between lateral positions with the movement of the thrust bar 90. This changes the alignment between the openings 62, 72 in the plates 60, 70 and adjusts the amount of airflow that can pass through the plates 60, 70 and into the intake 21 of the burner 20. In other words, the openings 62, 72 in the plates 60, 70 can be fully aligned when the compensator 50 is fully open, allowing a maximum amount of combustion air to enter the burner 20. When the openings 62, 72 of the plates 60, 70 are fully misaligned, the compensator 50 is closed, allowing only a minimum amount of combustion air to enter the burner 20. Minimal combustion air flow to maximum combustion air flow and anywhere in between can be achieved through the full lateral travel of the movable plate 70 with respect to the stationary plate 60.
In one exemplary position shown in FIG. 3A, the movable plate 70 can be moved laterally with respect to the stationary plate 60 to a first position such that the second openings 72 thereof are aligned with the first openings 62 of the stationary plate 60, which can control the air for the intake to a first level. For example, with the openings 62, 72 fully aligned, a maximum level of airflow can be allowed through the compensator 50 to the burner's intake 21. By contrast and as shown in FIGS. 3B and 3C, the movable plate 70 can be moved laterally with respect to the stationary plate 60 to a second position such that the second openings 72 are misaligned with respect to the first openings 62, which can control the air for the intake to a second level, which may be lower than the first level. For example, with the openings 62, 72 fully misaligned as in FIG. 3C, a minimum level of airflow may be allowed through the compensator 50 to the burner's intake 21. Any number of intermediate levels be, such as depicted in FIG. 3B, in which the openings are partially aligned or misaligned, can be used between fully aligned opened and fully misaligned closed conditions to control the airflow at intermediate levels.
As schematically depicted in FIG. 2 , support features 92, such as bearings, can support the thrust bars 90 in the heater. These support features or bearings 92 can be mounted from the infrastructure of the firebox's floor 17 (FIG. 1 ) of the fired heater 10 or can be mounted in other places of the heater. Any of the various couplings 80 between a given thrust bar 90 and a given movable plate 70 can be detached so the movement of the bar 90 does not in turn move that movable plate 70. In this way, disconnecting the removable coupling 80 can isolate the intake 21 of that particular burner 20. For example, that particular burner 20 may not be operated, or it may be set with the movable plate 70 at a fixed alignment for a fixed airflow rate.
As schematically depicted in FIG. 2 , the burners 20 are typically arranged in various rows. The uniform or substantially uniform orientation of the movable plates 70, and the uniform direction/magnitude of movable plates' movement lends each movable plate 70 to be connected to each other through the use of the rigid thrust bars 90. Accordingly, the compensator system 100 can include one bar 90 arranged with each row of burners 20, and a drive bar (or crossbar) 95 can be connected across the thrust bars 90. At least one actuator 110 is coupled to the drive bar 95 and is configured to move the thrust bars 90 in unison along the rows of burners 20 with the movement of the drive bar 95, thereby moving the sets of movable plates 70 together and adjusting each of the respective burners 20 simultaneously or substantially simultaneously.
Alternative arrangements can be used. For example, each row of the burners 20 can have a separate thrust bar 90 and actuator 110 to independently move the bar 90 and to adjust the compensators 50 for that row of the burners 20. Thus, one thrust bar 90 can be used per row of the burners 20 to individually control the row of burners 20. Alternatively, two or more sets of thrust bars 90 can be independently controlled by a common linear actuator 110. The sets of thrust bar 90 in turn can be connected to a rigid drive bar 95. The drive bar 95 can then be moved laterally through the use of a common linear actuator 110. In the end, different sections (rows and columns) of the burners 20 can have separate thrust bars 90 and actuators 110 for separate adjustment and control. In any case, airflow at the intakes 21 of various sections or rows of the burners 20 can be separately controlled.
As part of the control of the airflow for the burner intakes 21, the compensator system 100 can include a controller 120 and one or more sensors 122. The sensors 122 can be arranged with the actuators 110, for example. The one or more sensors 122 can be configured to measure one or more characteristics associated with the operation of the burners 20 or associated with another aspect of the fired heater 10, such as 0 2 level, BTU content, and the like. In turn, the controller 120 in communication with the sensors 122 can be configured and programmed to control the actuators 110 based on the measured characteristic. In an example, the sensor 122 can be an oxygen analyzer or meter, a fuel BTU composition meter/device, a calorimeter, or another suitable sensor.
For oxygen control, the sensor 122 can measure the 0 2 level in the firebox 14 of the fired heater 10 and can adjust, via the controller 120, the airflow level for the burners' intakes 21 by adjusting the compensators 50 to meet a desired oxygen level. For airflow control, the sensors 122 can measure the BTU content of the fuel into the burners and can adjust, via the controller 120, the airflow level for the burners' intakes 21 by adjusting the compensators 50 to meet a desired level.
The compensator system 100 disclosed herein can address deficiencies found in existing systems. The compensator system 100 can be configured to further control the amount of excess air entering the radiant firebox 14 through the burners 20 during the operation of the fired heater 10. Moreover, the compensator system 100 can be configured to compensate for the stack damper 19 or induced fan damper of the fired heater 10.
The compensator system 100 can be arranged as a rigid and precise system for controlling the amount of air introduced through each burner 20, and the compensator system 100 can ensure that all of the burners 20 act as a single system. The movable plates 70 that control the amount of air going through each burner 20 can all be rigidly linked together. In this way, the compensator system 100 allows the fired heater 10 to safely operate with the least amount of excess air, resulting in significant fuel savings and the generation of less pollution. Existing heaters around the world are not capable of operating at reduced levels of excess air.
Understanding the compensator system 100, discussion turns to further details related to the compensators 50. FIG. 4 illustrates a front elevational view of compensator assemblies 50 of the disclosed system arranged at intakes 21 for the burners 20 of the fired heater. Three adjacent compensator assemblies 50 are shown for three adjacent burners 20 as an example arrangement.
In this front elevational view, the movable plates 70 noted above are not shown in front of the stationary plates 60. This allows the openings 62 of the stationary plates 60 to be seen. The thrust bar 90 is shown passing laterally in front of the intakes 21 for the burners 20. The bar 90 has couplings 80 for attaching to the movable plates (70), which are not shown as noted above. The compensator assemblies 50 each include a housing 52 having an interior 53 and having an opening 54, which is covered by the stationary plates 60, movable plates 70, and associated track/guides. Supports 51 hang from crossbeams of the heater's floor 17 to support the housings 52, which are attached to the burners 20.
Further details of the compensator 50 are provided in FIGS. 5A-5C. In particular, FIG. 5A illustrates a front elevational view of a compensator 50 in more detail, and FIG. 5B illustrates a side elevational view of the compensator 50. Meanwhile, FIG. 5C illustrates another side elevational view of disassembled components of the compensator 50.
As noted above and depicted here in more detail, the compensator 50 includes a housing 52 configured to affix to the intake 21 for a burner 20. As shown, the intake 21 can use a conventional louvered register 22 that can be rotated to adjust airflow. The stationary plate 60 is disposed across the housing 52 and defines one or more first openings 62 therein. As shown here, the stationary plate 60 can have two or more adjacent openings 62, which can be identical to one another.
Bar 90 is movable in a lateral direction relative to the stationary plate 60 and couples with the coupling 80 to the movable plate 70 disposed adjacent to the stationary plate 60. Similar to the stationary plate 60, the movable plate 70 defines adjacent openings 72. These openings 72 can be identical to one another, and they can be identical to the stationary plate's openings 62. Although the openings 62, 72 can be identical, other configurations can be used depending on the implementation and the control desired for the airflow.
The movable plate 70 is movable in a lateral direction when sliding the bar 90, as noted above, to change the alignment between the openings 62, 72 and control the amount of airflow that can pass through the compensator 50 to the intake 21 of the burner 20. A breaker plate 58 can be disposed adjacent to the movable plate 70 and can be configured to interrupt the airflow to the first and second openings 62, 72 in the event of significant, directional wind, etc. For example, the breaker plate 58 can be affixed to flanges 57 on support beams 56 extending from the stationary plate 60.
Several friction reducers 64, 74 can support the movable plate 70 on the compensator 50 to reduce the friction and to serve as a track or guide when the movable plate 70 is moved. For example, the friction reducers can include support plates 64, 74 composed of polytetrafluoroethylene (PTFE) and disposed between surfaces of the movable plate 70 and surfaces of the compensator assembly 50. As discussed in more detail below, these support plates 64, 74 can be positioned along the top and the bottom of the movable plate 70. Other forms of friction reduction can be used for the friction reducers 64, 74, such as bearings, rollers, etc.
As shown in FIGS. 5A-5C, the housing 52 can affix to the burner's louvered register 22 by bolting a first end of the housing 52 to a face or flange on the body of the louvered register 22. The stationary plate 60 can bolt to a face plate 55 onto the housing 52 so that the stationary plate 60 fits across the compensator's housing 52. Opposing top friction reducers 64 a on the compensator 50 can support opposing top friction reducers 74 a on the front and back of the movable plate 70. A bottom friction reducer 64 b can support an opposing friction reducer 74 b on a bottom edge of the movable plate 70.
As can be seen, the movable plate 70 of the compensator assembly 50 can be moved laterally with respect to the position of the stationary plate 60. In turn, the configuration/position of the openings 62, 72 can either increase or decrease the amount of combustion air capable of entering the burner 20 during operation. The openings 62, 72 in both plates 60, 70 are fully aligned when the compensator assembly 50 is fully open, allowing a maximum amount of combustion air to enter the burner 20. When the plates 60, 70 are fully misaligned, the compensator assembly 50 is closed, allowing a minimum amount of combustion air to enter the burner 20. Minimal combustion air flow to maximum combustion air flow and anywhere in between is achieved through the full lateral travel of the movable plate 70.
As shown in FIGS. 5A-5C, the coupling 80 can include a mount 78 disposed on the movable plate 70 and can include a flange 88 disposed on the thrust bar 90. During heater operation, it is not uncommon that an individual burner 20 needs to be taken out of service. This may require the movable plate 70 to be placed in (and to remain in) the fully closed position. The coupling 80 between the movable plate 70 and the thrust bar 90 can be removable (or disengaged) from the movable plate 70, allowing operators to easily take a burner out of service and just as quickly put it back into service. The removable coupling 80 makes it i) easy to isolate a single burner 20 without impacting the operation of the rest of the system and ii) easy to verify disengagement by the operators.
As best shown in the isolated plan view of FIG. 6 , for example, clamps 82 can affix the coupling 80 to the bar 90. The mount 78 can be a split bracket, which is affixed vertically on the movable plate 70 and has several side holes. The flange 88 can fit between the split bracket mount 78, and a locking pin(s) 86 can removably connect the flange 88 to the mount 78 through the side holes.
As disclosed herein, the openings 62, 72 in the plates 60, 70 are configured to vary the airflow for the intake. To isolate the airflow to the openings 62, 72, curbs 68, lips, or seals as shown in FIG. 5A can be disposed between the movable plate 70 and the stationary plate 60 on each side of the openings 62, 72, The curbs 68 can be configured to reduce leakage of the airflow from the sides between the plates 60, 70. The friction reducers 64, 74 may help leakage of the airflow from the top and bottom spaces between the plates 60, 70.
The openings 62, 72 in the plates 60, 70 can be sized and/or shaped to vary the intake of the airflow linearly between different levels with the movement between the lateral positions of the plates 60, 70. For example, FIG. 7A schematically illustrates a shape for an opening 60 according to one embodiment, and FIG. 7B schematically illustrates the openings 62, 72 in an intermediate state of alignment.
As shown in FIG. 7A, an opening 62 for the stationary plate 60 can have a quadrilateral shape including sides 63 of unequal length. Vertical sides 63 a-b are parallel to one another, one lateral side 63 c is orthogonal to the vertical sides 63 a-b, and the other lateral side 63 d is oblique to the vertical sides 63 a-b. The opening (72) for the movable plate (70) can be identical.
As shown in FIG. 7B, a pair of first openings 62 for the stationary plate (60) have a same width W in a lateral direction as a pair of second openings 72 for the movable plate (70). The openings 62, 72 for the pairs are separated by a separation at least as great as the width W so that the pairs of openings 62, 72 can be completely aligned and completely misaligned with the lateral movement of the movable plate 70. For most operational needs, the openings 62, 72 can be custom designed to create a linear relationship between the movable plate's incremental movement and the incremental change to the rate of airflow that can pass in the open area A of the openings 62, 72.
FIG. 8 illustrates a graph 150 showing a burner's firing rate relative to a percentage opening for a two-blade air register and for a compensator assembly of the present disclosure. The two-blade air register's firing rate is graphed as line 152 with the air compensator opening adjusted between 10% to 100%. This gives a firing rate percentage of between about 25% to 100%. As noted, the two-blade air register is adjusted manually according to the prior art so that the firing rate percentage is fixed during the operation of a fired heater and cannot be adjusted automatically as the fired heater operates.
By contrast, the air compensator 50 of the present disclosure is automatically adjustable as noted herein so a variable firing rate can be controlled during operation. As shown by line 154, the compensator assembly of the present disclosure can provide a firing rate that varies from about 10% to 100% for air compensator opening between about 10% to 100%.
It will be apparent to those skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings that modifications, combinations, sub-combinations, and variations can be made without departing from the spirit or scope of this disclosure. Likewise, the various examples described may be used individually or in combination with other examples. Those skilled in the art will appreciate various combinations of examples not specifically described or illustrated herein that are still within the scope of this disclosure. In this respect, it is to be understood that the disclosure is not limited to the specific examples set forth and the examples of the disclosure are intended to be illustrative, not limiting.
As used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise. Similarly, the adjective “another,” when used to introduce an element, is intended to mean one or more elements. The terms “comprising,” “including,” “having” and similar terms are intended to be inclusive such that there may be additional elements other than the listed elements.
Additionally, where a method described above or a method claim below does not explicitly require an order to be followed by its steps or an order is otherwise not required based on the description or claim language, it is not intended that any particular order be inferred. Likewise, where a method claim below does not explicitly recite a step mentioned in the description above, it should not be assumed that the step is required by the claim.
It is noted that the description and claims may use geometric or relational terms, such as right, left, above, below, upper, lower, top, bottom, linear, arcuate, elongated, parallel, perpendicular, etc. These terms are not intended to limit the disclosure and, in general, are used for convenience to facilitate the description based on the examples shown in the figures. In addition, the geometric or relational terms may not be exact. For instance, walls may not be exactly perpendicular or parallel to one another because of, for example, roughness of surfaces, tolerances allowed in manufacturing, etc., but may still be considered to be perpendicular or parallel.

Claims

What is claimed is:

1. A compensator for a burner of a fired heater or furnace, the burner having an intake for airflow, the compensator comprising:

a stationary plate disposed across the intake and across a direction of the airflow through the intake, the stationary plate including one or more first openings; and

a movable plate disposed adjacent to the stationary plate and including one or more second openings, the movable plate being movable between first and second lateral positions with respect to the stationary plate to control the airflow through the intake,

wherein in the first lateral position, the one or more second openings of the movable plate are at least partially aligned with the one or more first openings of the stationary plate, thereby defining a first level of airflow through the intake,

wherein in the second lateral position, the one or more second openings of the movable plate are at least partially misaligned with the one or more first openings of the stationary plate, thereby defining a second level of airflow through the intake, and

wherein the airflow through the intake at the second level is less than the air flow through the intake at the first level.

2. The compensator of claim 1, wherein in the first lateral position, the one or more second openings are substantially aligned with the one or more first openings such that the first level is a maximum amount of airflow allowed through the intake, and in the second lateral position, the one or more second openings are substantially misaligned with the one or more first openings such that the second level is a minimum amount of airflow allowed through the intake.

3. The compensator of claim 1, wherein the first and second openings are configured to vary the airflow for the intake in a linear relationship between the first and second levels with the movement of the movable plate between the first and second lateral positions.

4. The compensator of claim 1, further comprising a movable support member being movable in a lateral direction relative to the stationary plate that is generally transverse to the direction of the airflow through the intake, the movable plate being releasably coupled to the movable support member, and the movable support member being configured to move the movable plate with respect to the stationary plate between the first and second lateral positions.

5. The compensator of claim 4, wherein the movable support member is a slidable elongated bar.

6. The compensator of claim 4, further comprising an actuator configured to slide the bar with respect to the stationary plate.

7. The compensator of claim 4, wherein a coupling removably connects the movable plate to the bar, and the coupling comprises a mount disposed on the movable plate, a flange disposed on the bar, and a locking pin removably connecting the flange to the mount.

8. The compensator of claim 1, further comprising a housing configured to affix to the burner and having an opening, a first end of the housing communicating with the intake, and a second end of the housing having the stationary plate disposed across the opening.

9. The compensator of claim 1, further comprising a breaker plate disposed adjacent to the movable plate and being configured to interrupt the airflow to the first and second openings to address interference due to wind directions.

10. The compensator of claim 1, further comprising a friction reducer supporting the movable plate on the compensator.

11. The compensator of claim 10, wherein the friction reducer comprises a support plate, track, or guide disposed between a first surface of the movable plate and a second surface of the compensator.

12. The compensator of claim 1, further comprising at least one sensor being configured to measure one or more characteristics associated with operation of the burner, and a controller in communication with the sensor and being configured to control the moveable plate based on the measured characteristic to adjust the airflow through the intake.

13. The compensator of claim 12, wherein the sensor comprises one or more of an oxygen sensor, a fuel gas BTU sensor, and a calorimeter.

14. The compensator of claim 1, further comprising a curb disposed between the movable plate and the stationary plate on each side of the one or more first openings, the curbs being configured to reduce leakage of the air from the sides between the plates.

15. The compensator of claim 1, wherein the one or more first openings comprise two first openings having a first width in the lateral direction, the two first openings separated by a first separation at least as great as the first width, and wherein the one or more second openings comprise two second openings having a second width in the lateral direction, the two second openings separated by a second separation at least as great as the second width.

16. The compensator of claim 15, wherein the first width is substantially equal to the second width; wherein the first separation is substantially equal to the second separation.

17. The compensator of claim 15, wherein a first shape of the first openings is the same as a second shape of the second openings.

18. The compensator of claim 1, wherein the one or more first and second openings each comprise a quadrilateral having sides of unequal length, vertical ones of the sides being parallel to one another, a lateral one of the sides being orthogonal to the vertical sides, another lateral one of the sides being oblique to the vertical sides.

19. A compensator system for a fired heater or furnace having a plurality of burners, each burner having an intake for airflow, the compensator system comprising:

at least one movable support member being movable laterally relative to the intakes in a direction generally transverse to a direction of the airflow;

a plurality of stationary plates disposed across the intakes of the burners, respectively, each of the stationary plates including one or more first openings; and

a plurality of movable plates disposed adjacent to the plurality of stationary plates, respectively, each of the movable plates including one or more second openings, and each movable plate being releasably coupled to the movable support member; and

a controller configured to move each of the plurality of movable plates between first and second lateral positions via movement of the moving support member to control the airflow through the intake of each burner, respectively,

wherein in the first lateral position, the one or more second openings of each movable plate are at least partially aligned with the one or more first openings of a respective stationary plate, thereby defining a first level of airflow through the intake of each burner, respectively,

wherein in the second lateral position, the one or more second openings of each movable plate are at least partially misaligned with the one or more first openings of the respective stationary plate, thereby defining a second level of airflow through the intake of each burner, respectively, and

wherein the airflow at the second level is less than the air flow at the first level.

20. The compensator system of claim 19, wherein the controller is configured to move each of the movable plates between the first and second lateral positions at substantially the same time via the movable support member.

21. The compensator system of claim 20, wherein the controller automatically controls the airflow between the first and second levels.

22. The compensator system of claim 19, wherein an actuator coupled to the movable support member is configured to slide the movable support member with respect to the stationary plates.

23. The compensator system of claim 22, wherein the movable support member is an elongated bar.

24. The compensator system of claim 19, further comprising a bearing configured to support the bar to a portion of the fired heater.

25. A method of controlling airflow through a fired heater or furnace comprising the step of adjusting the airflow using the compensator system according to claim 19.

26. A fired heater or furnace, comprising:

a radiant firebox having a floor, walls, a roof, and a stack;

a plurality of burners disposed in the firebox at the floor, walls, or roof, each of the burners having an intake for airflow; and

a compensator according to claim 1 disposed at the intake of one or more of the burners.

27. The fired heater or furnace of claim 26, wherein the burners are arranged in at least two rows; and at least two movable support members are each arranged on one of the at least two rows.

28. The fired heater or furnace of claim 27, further comprising at least one actuator coupled to the at least two movable support members and being configured to move the at least two movable support members along the rows.

29. The fired heater or furnace of claim 28, wherein each movable support member is an elongated bar.

30. The fired heater or furnace of claim 26, wherein a controller is configured to automatically adjust the airflow through one or more of the burners via one or more of the compensators between the first and second levels.