COMPENSATOR FOR CONTROLLING AIRFLOW IN FIRED HEATER

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.

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.1shows an example of a fired heater10, which includes a burner section12, a radiant section or firebox14, a convection section16, and a stack18. The burners20are often arranged in rows at the floor (hearth)17of the firebox14so the flames from the burners20can produce radiant heat in the firebox14. The radiant heat in the firebox14is in turn transferred to organic materials conveyed in a continuous path through radiant tube coils30that line the interior walls of the firebox14. The walls of the firebox14can have ceramic fiber insulation or castable refractory lining15, which can reduce heat loss, can radiate heat back toward the back (shadowed) side of the tube coils30, and can keep the temperatures of the coils30as designed. For efficiency, the convection section16allows heat to be transferred to the conveyed organics in convection coils40through the process of convective heat transfer as heated flue gases rise out of the firebox14, through the convection section16, and up and out the flue gas stack18.

The quantity and location of the burners20within the radiant firebox14can vary. Nevertheless, the burners20are typically organized in rows, columns, and the like in the floor (hearth), walls, or roof (arch). The fired heater10must 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 firebox14of the fired heater10, ensuring the correct amount of air is available for the safe combustion of the fuel introduced into the radiant firebox14through the burners20. Any air introduced into the radiant firebox14through the burners20that 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 firebox14through the burners20, the volume and rate of the combustion airflow is dictated by the draft (negative pressure) within the radiant firebox14. For a natural-draft fired heater, this draft is generated by the buoyancy effect of the hot flue gas within the fired heater10and its stack18. A damper19, typically located in the stack18, 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 firebox14. The draft for the fan is regulated by the use of a damper19(or similar) or by varying the speed of the fan itself. The amount of combustion air flow through the fired heater10can be further controlled at each individual burner20by using a secondary damper or a burner register22at the burner's intake21.

The heater10should not be operated in a condition in which there is not enough air available in the firebox14to ensure the complete burning of the fuel introduced. For this reason, operators typically operate the fired heater10with 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 heater10can 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 firebox14through the burners20using just a stack damper19or 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 heater10and reduce pollution generated.

Finer control of any excess air in the heater10may require the accurate use of the burner registers22. The burner registers22used individually on each burner20typically have a louver design. Each burner register22is operated manually and independently to control the air for its associated burner20. As a result, adjusting the burner register22can be extremely difficult to automate. Attempts to automate the operation of the burner register22are compounded even further with the increase in the number of burners20used in a fired heater design. With the ever-changing needs in the volume of combustion air needed during operations of the fired heater10, it is impractical for an operator to manually fine-tune the burner registers22to control the amount of combustion air that enters through the burners20into the radiant firebox14.

Attempts in the past to automatically control the amount of combustion air entering through the burner registers22have 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 registers22. Rotation of the jackshaft can open and close the burner registers22to 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 registers22tend 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 burners20and the heater10overall. In addition, it is difficult to take a given burner20out 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 registers22for the burners20. This rotational arrangement is rarely done, especially when there are many burners20in the fired heater10. 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 register22with 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 registers22can produce isolated areas within the firebox14that do not have sufficient air for combustion from an operational perspective.

In some implementations, multiple burners20can 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 burners20. 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 heater10will change the combustion air distribution to the different burners20attached 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 firebox14do 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

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.

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 firebox14through the burners20and reduces excess air.

Referring to the figures, the present disclosure relates to a compensator system100for controlling the amount of combustion air introduced through each burner20for operating the heater10at reduced levels of excess air. The compensator system100is designed to allow the fired heater10to safely operate with the least amount of excess air, resulting in significant fuel savings and the generation of less pollution. This compensator system100will allow fired heaters to achieve a level of performance never even thought of when originally built. And the compensator system100can be an automated system, such as by allowing each of the compensators50of the compensator system100to operate at the same time.

FIG.2illustrates a plan view of multiple burners20for a fired heater10having a compensator system100according to the present disclosure. The plan view shows a portion of the fired heater10with a total quantity of thirty-six burners20organized in a total of 4 rows, for example. As will be appreciated, but not shown inFIG.2, the fired heater10includes a radiant firebox having a floor and a stack. The burners20can be installed at the floor to produce radiant heat for the firebox. In any event, the fired heater10can 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 burners20within the radiant firebox14can vary, and the burners20can be organized in rows, columns, and the like in the floor (hearth), walls, or roof (arch) of the heater10.

Each of the burners20has an intake21for combustion air. As noted, the intake21typically includes a louvered register22that can be rotated to adjust the airflow through the intake21. The compensator system100includes one or more compensators50(also referred to herein as compensator assemblies) used for at least one or more of the burners' intakes21. As shown in the example ofFIG.2, one compensator assembly50can be mounted onto the intake21of each burner20.

Each compensator50may include a housing or transition body52(FIG.3A) configured to attach to the intake21of the respective burner20. The housing or transition body52has a stationary (or back) plate60covering the intake21to control the passage of combustion air into the intake21. In general, the stationary plate60can be characterized as a baffle, a wall, barrier, or the like that is designed to cover the intake21for the air into to the burner20. The stationary plate60can have one or more openings62(FIGS.3A-3C) for passage of airflow therethrough.

Each compensator50also has a movable (or front) plate70disposed adjacent to and in front of the stationary plate60at the intakes21. The movable plates70can be characterized as sliding doors, louvers, or the like. Like the stationary plates60, the movable plates70can have openings72(FIGS.3A-3C) for the passage of airflow.

Couplings80connect the movable plates70to a movable support member90of the system100. The movable support member90can be, in one example, an elongated thrust bar. The couplings80can be selectively connectable to the movable plates70. To adjust the airflow into the intake21of each burner20, respectively, each movable plate70can be moved laterally with respect to the stationary plate60, that is between lateral positions, by sliding the corresponding movable support member90in a direction generally transverse to the direction of airflow into the burner intake (or in a direction of the length of the elongated90). The selected lateral position of the moveable plate70can change the alignment between the openings62,72in the plates60,70, thereby adjusting the amount of airflow that can pass through the plates60,70and into the intake21of the respective burner20.

For example, the movable plate70can be positioned laterally, i.e. in a lateral position, with respect to the position of the adjacent stationary plate60disposed across the intake21of the burner20. In turn, the configuration/position of openings62in the plates60,70can either increase or decrease the amount of combustion air capable of entering the burner's intake21during operation depending upon the alignment of the openings. The one or more elongated bars90are slidable relative to the burner intakes21using one or more actuators110. Movement of the bars90in turn alters the lateral position of the movable plates70relative to the stationary plates60at the intakes21. This positioning thereby adjusts the amount of airflow permitted into the intake21of the burner20.

FIGS.3A-3Cillustrate sectional views of a compensator50ofFIG.2in different states of operation. The stationary plate60includes one or more first openings62therein and the movable plate70includes one or more second openings72. The movable plate70is coupled to the thrust bar90by the coupling80and is disposed adjacent to the stationary plate60. Like the stationary plate60, the movable plate70defines one or more second openings72therein. To adjust the airflow into the intake21of the burner20, the movable plate70can be moved between lateral positions with the movement of the thrust bar90. This changes the alignment between the openings62,72in the plates60,70and adjusts the amount of airflow that can pass through the plates60,70and into the intake21of the burner20. In other words, the openings62,72in the plates60,70can be fully aligned when the compensator50is fully open, allowing a maximum amount of combustion air to enter the burner20. When the openings62,72of the plates60,70are fully misaligned, the compensator50is closed, allowing only a minimum amount of combustion air to enter the burner20. Minimal combustion air flow to maximum combustion air flow and anywhere in between can be achieved through the full lateral travel of the movable plate70with respect to the stationary plate60.

In one exemplary position shown inFIG.3A, the movable plate70can be moved laterally with respect to the stationary plate60to a first position such that the second openings72thereof are aligned with the first openings62of the stationary plate60, which can control the air for the intake to a first level. For example, with the openings62,72fully aligned, a maximum level of airflow can be allowed through the compensator50to the burner's intake21. By contrast and as shown inFIGS.3B and3C, the movable plate70can be moved laterally with respect to the stationary plate60to a second position such that the second openings72are misaligned with respect to the first openings62, which can control the air for the intake to a second level, which may be lower than the first level. For example, with the openings62,72fully misaligned as inFIG.3C, a minimum level of airflow may be allowed through the compensator50to the burner's intake21. Any number of intermediate levels be, such as depicted inFIG.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 inFIG.2, support features92, such as bearings, can support the thrust bars90in the heater. These support features or bearings92can be mounted from the infrastructure of the firebox's floor17(FIG.1) of the fired heater10or can be mounted in other places of the heater. Any of the various couplings80between a given thrust bar90and a given movable plate70can be detached so the movement of the bar90does not in turn move that movable plate70. In this way, disconnecting the removable coupling80can isolate the intake21of that particular burner20. For example, that particular burner20may not be operated, or it may be set with the movable plate70at a fixed alignment for a fixed airflow rate.

As schematically depicted inFIG.2, the burners20are typically arranged in various rows. The uniform or substantially uniform orientation of the movable plates70, and the uniform direction/magnitude of movable plates' movement lends each movable plate70to be connected to each other through the use of the rigid thrust bars90. Accordingly, the compensator system100can include one bar90arranged with each row of burners20, and a drive bar (or crossbar)95can be connected across the thrust bars90. At least one actuator110is coupled to the drive bar95and is configured to move the thrust bars90in unison along the rows of burners20with the movement of the drive bar95, thereby moving the sets of movable plates70together and adjusting each of the respective burners20simultaneously or substantially simultaneously.

Alternative arrangements can be used. For example, each row of the burners20can have a separate thrust bar90and actuator110to independently move the bar90and to adjust the compensators50for that row of the burners20. Thus, one thrust bar90can be used per row of the burners20to individually control the row of burners20. Alternatively, two or more sets of thrust bars90can be independently controlled by a common linear actuator110. The sets of thrust bar90in turn can be connected to a rigid drive bar95. The drive bar95can then be moved laterally through the use of a common linear actuator110. In the end, different sections (rows and columns) of the burners20can have separate thrust bars90and actuators110for separate adjustment and control. In any case, airflow at the intakes21of various sections or rows of the burners20can be separately controlled.

As part of the control of the airflow for the burner intakes21, the compensator system100can include a controller120and one or more sensors122. The sensors122can be arranged with the actuators110, for example. The one or more sensors122can be configured to measure one or more characteristics associated with the operation of the burners20or associated with another aspect of the fired heater10, such as 0 2 level, BTU content, and the like. In turn, the controller120in communication with the sensors122can be configured and programmed to control the actuators110based on the measured characteristic. In an example, the sensor122can be an oxygen analyzer or meter, a fuel BTU composition meter/device, a calorimeter, or another suitable sensor.

For oxygen control, the sensor122can measure the 0 2 level in the firebox14of the fired heater10and can adjust, via the controller120, the airflow level for the burners' intakes21by adjusting the compensators50to meet a desired oxygen level. For airflow control, the sensors122can measure the BTU content of the fuel into the burners and can adjust, via the controller120, the airflow level for the burners' intakes21by adjusting the compensators50to meet a desired level.

The compensator system100disclosed herein can address deficiencies found in existing systems. The compensator system100can be configured to further control the amount of excess air entering the radiant firebox14through the burners20during the operation of the fired heater10. Moreover, the compensator system100can be configured to compensate for the stack damper19or induced fan damper of the fired heater10.

The compensator system100can be arranged as a rigid and precise system for controlling the amount of air introduced through each burner20, and the compensator system100can ensure that all of the burners20act as a single system. The movable plates70that control the amount of air going through each burner20can all be rigidly linked together. In this way, the compensator system100allows the fired heater10to 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 system100, discussion turns to further details related to the compensators50.FIG.4illustrates a front elevational view of compensator assemblies50of the disclosed system arranged at intakes21for the burners20of the fired heater. Three adjacent compensator assemblies50are shown for three adjacent burners20as an example arrangement.

In this front elevational view, the movable plates70noted above are not shown in front of the stationary plates60. This allows the openings62of the stationary plates60to be seen. The thrust bar90is shown passing laterally in front of the intakes21for the burners20. The bar90has couplings80for attaching to the movable plates (70), which are not shown as noted above. The compensator assemblies50each include a housing52having an interior53and having an opening54, which is covered by the stationary plates60, movable plates70, and associated track/guides. Supports51hang from crossbeams of the heater's floor17to support the housings52, which are attached to the burners20.

Further details of the compensator50are provided inFIGS.5A-5C. In particular,FIG.5Aillustrates a front elevational view of a compensator50in more detail, andFIG.5Billustrates a side elevational view of the compensator50. Meanwhile,FIG.5Cillustrates another side elevational view of disassembled components of the compensator50.

As noted above and depicted here in more detail, the compensator50includes a housing52configured to affix to the intake21for a burner20. As shown, the intake21can use a conventional louvered register22that can be rotated to adjust airflow. The stationary plate60is disposed across the housing52and defines one or more first openings62therein. As shown here, the stationary plate60can have two or more adjacent openings62, which can be identical to one another.

Bar90is movable in a lateral direction relative to the stationary plate60and couples with the coupling80to the movable plate70disposed adjacent to the stationary plate60. Similar to the stationary plate60, the movable plate70defines adjacent openings72. These openings72can be identical to one another, and they can be identical to the stationary plate's openings62. Although the openings62,72can be identical, other configurations can be used depending on the implementation and the control desired for the airflow.

The movable plate70is movable in a lateral direction when sliding the bar90, as noted above, to change the alignment between the openings62,72and control the amount of airflow that can pass through the compensator50to the intake21of the burner20. A breaker plate58can be disposed adjacent to the movable plate70and can be configured to interrupt the airflow to the first and second openings62,72in the event of significant, directional wind, etc. For example, the breaker plate58can be affixed to flanges57on support beams56extending from the stationary plate60.

Several friction reducers64,74can support the movable plate70on the compensator50to reduce the friction and to serve as a track or guide when the movable plate70is moved. For example, the friction reducers can include support plates64,74composed of polytetrafluoroethylene (PTFE) and disposed between surfaces of the movable plate70and surfaces of the compensator assembly50. As discussed in more detail below, these support plates64,74can be positioned along the top and the bottom of the movable plate70. Other forms of friction reduction can be used for the friction reducers64,74, such as bearings, rollers, etc.

As shown inFIGS.5A-5C, the housing52can affix to the burner's louvered register22by bolting a first end of the housing52to a face or flange on the body of the louvered register22. The stationary plate60can bolt to a face plate55onto the housing52so that the stationary plate60fits across the compensator's housing52. Opposing top friction reducers64aon the compensator50can support opposing top friction reducers74aon the front and back of the movable plate70. A bottom friction reducer64bcan support an opposing friction reducer74bon a bottom edge of the movable plate70.

As can be seen, the movable plate70of the compensator assembly50can be moved laterally with respect to the position of the stationary plate60. In turn, the configuration/position of the openings62,72can either increase or decrease the amount of combustion air capable of entering the burner20during operation. The openings62,72in both plates60,70are fully aligned when the compensator assembly50is fully open, allowing a maximum amount of combustion air to enter the burner20. When the plates60,70are fully misaligned, the compensator assembly50is closed, allowing a minimum amount of combustion air to enter the burner20. Minimal combustion air flow to maximum combustion air flow and anywhere in between is achieved through the full lateral travel of the movable plate70.

As shown inFIGS.5A-5C, the coupling80can include a mount78disposed on the movable plate70and can include a flange88disposed on the thrust bar90. During heater operation, it is not uncommon that an individual burner20needs to be taken out of service. This may require the movable plate70to be placed in (and to remain in) the fully closed position. The coupling80between the movable plate70and the thrust bar90can be removable (or disengaged) from the movable plate70, allowing operators to easily take a burner out of service and just as quickly put it back into service. The removable coupling80makes it i) easy to isolate a single burner20without 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 ofFIG.6, for example, clamps82can affix the coupling80to the bar90. The mount78can be a split bracket, which is affixed vertically on the movable plate70and has several side holes. The flange88can fit between the split bracket mount78, and a locking pin(s)86can removably connect the flange88to the mount78through the side holes.

As disclosed herein, the openings62,72in the plates60,70are configured to vary the airflow for the intake. To isolate the airflow to the openings62,72, curbs68, lips, or seals as shown inFIG.5Acan be disposed between the movable plate70and the stationary plate60on each side of the openings62,72, The curbs68can be configured to reduce leakage of the airflow from the sides between the plates60,70. The friction reducers64,74may help leakage of the airflow from the top and bottom spaces between the plates60,70.

The openings62,72in the plates60,70can 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 plates60,70. For example,FIG.7Aschematically illustrates a shape for an opening60according to one embodiment, andFIG.7Bschematically illustrates the openings62,72in an intermediate state of alignment.

As shown inFIG.7A, an opening62for the stationary plate60can have a quadrilateral shape including sides63of unequal length. Vertical sides63a-bare parallel to one another, one lateral side63cis orthogonal to the vertical sides63a-b, and the other lateral side63dis oblique to the vertical sides63a-b. The opening (72) for the movable plate (70) can be identical.

As shown inFIG.7B, a pair of first openings62for the stationary plate (60) have a same width W in a lateral direction as a pair of second openings72for the movable plate (70). The openings62,72for the pairs are separated by a separation at least as great as the width W so that the pairs of openings62,72can be completely aligned and completely misaligned with the lateral movement of the movable plate70. For most operational needs, the openings62,72can 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 openings62,72.

FIG.8illustrates a graph150showing 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 line152with 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 compensator50of the present disclosure is automatically adjustable as noted herein so a variable firing rate can be controlled during operation. As shown by line154, 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.