CN115087145A

CN115087145A - Heater bundle with local power switching

Info

Publication number: CN115087145A
Application number: CN202210233701.4A
Authority: CN
Inventors: 马克·艾佛利; 特雷弗·史密斯; 雅各布·斯布勒
Original assignee: Watlow Electric Manufacturing Co
Current assignee: Watlow Electric Manufacturing Co
Priority date: 2021-03-10
Filing date: 2022-03-10
Publication date: 2022-09-20
Also published as: JP2022140402A; EP4057775A3; EP4057775A2; CA3151372A1; MX2022002935A; KR20220127173A

Abstract

A heater system includes a heater bundle. The heater bundle includes at least one heater assembly, wherein the heater assembly includes a plurality of heater cells, and more than one heater cell defines at least one independently controlled heating zone. The heater bundle includes a plurality of power supply leads electrically connected to independently controlled heating zones. The heating system comprises means for determining the temperature and at least one power switch arranged close to the heater bundle. The heater system includes at least one controller configured to modulate power over the supply conductor to the independently controlled heating zones based on the determined temperature to provide a desired power output along the length of the heater assembly. The controller is configured to provide power to the power switch.

Description

Heater bundle with local power switching

Cross Reference to Related Applications

This application is a continuation-in-part application of U.S. application No. 16/272,668 entitled "Heater Bundle for Adaptive Control," filed on day 2, month 11, 2019, which is a continuation of U.S. application No. 15/058,838 filed on day 2, month 3, 2016 (now U.S. patent No.10,247,445). The above disclosure is incorporated by reference herein in its entirety.

Technical Field

The present invention relates to electric heaters, and more particularly to heaters, such as heat exchangers, for heating a fluid stream.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

The fluid heater may be in the form of a cartridge heater having a rod arrangement to heat fluid flowing along or past the outer surface of the cartridge heater. The cartridge heater may be arranged inside the heat exchanger for heating the fluid flowing through the heat exchanger. If the cartridge heater is not completely sealed, moisture and fluids can enter the cartridge heater, thereby contaminating the insulation material that electrically isolates the resistive heating element from the metal sheath of the cartridge heater, resulting in dielectric breakdown and thus heater failure. Moisture can also cause a short circuit between the power supply leads and the outer metal sheath. Failure of the cartridge heater can result in costly downtime of the equipment in which the cartridge heater is used.

Disclosure of Invention

The invention provides a heater system including a heater bundle. The heater bundle includes at least one heater assembly, wherein more than one heater assembly includes a plurality of heater units, and the more than one heater units define at least one independently controlled heating zone. The heater bundle includes a plurality of power supply leads electrically connected to independently controlled heating zones. The heating system includes a means for determining a temperature and at least one power switch disposed proximate the heater bundle. The heater system includes at least one controller configured to provide control signals to at least one power switch such that the power switch modulates power to the independently controlled heating zones via the supply conductor based on the determined temperature to provide a desired power output along the length of the at least one heater assembly.

In variants of the invention, it can be implemented alone or in any combination: at least one power switch is disposed within the envelope; the heater system further comprises a temperature regulating device for cooling the jacket; the temperature regulating device uses a liquid to cool the envelope; the temperature regulating device uses a pressurized air flow to cool the envelope; providing a pressurized airflow inside the envelope and outside the envelope; the envelope is isolated from the outside atmosphere; a thermostat to cool the envelope using an internal fluid cooling flow and an external fluid cooling flow, each cooling flow coupled through a heat exchanger; the temperature adjustment device uses at least one of a thermoelectric element and a refrigeration system to cool the envelope; at least one controller disposed within the envelope; at least one controller remote from the heater bundle and in communication with the at least one power switch wirelessly and through at least one of the plurality of power conductors; a heat sink is disposed proximate to the at least one power switch.

In another embodiment, the heater system includes a heater bundle and the heater bundle includes at least one heater assembly, wherein more than one heater assembly includes a plurality of heater units and the more than one heater units define at least one independently controlled heating zone. The heater bundle includes a plurality of power supply leads electrically connected to independently controlled heating zones. The heating system comprises means for determining at least one of heating conditions and heating requirements. The heater system includes at least one power switch disposed proximate the heater bundle. The heater system includes at least one controller configured to provide control signals to the at least one power switch such that the power switch modulates power to the independently controlled heating zones via the supply conductors based on at least one of heating conditions and heating requirements to provide a desired power output along the length of the at least one heater assembly.

In a variant of this embodiment, it can be implemented alone or in any combination: the heater system includes an enclosure and at least one power switch is disposed within the enclosure; at least one controller disposed within the envelope; the at least one controller is remote from the heater bundle and communicates wirelessly and through at least one of the plurality of power conductors with the at least one power switch; at least one of the heating conditions and heating requirements is selected from the group consisting of a lifetime of the heater unit, a reliability of the heater unit, a size of the heater unit, a cost of the heater unit, a local heater flux, characteristics and operation of the heater unit, and an overall power output; a heat sink is disposed proximate to the at least one power switch.

In another embodiment, a heater system includes a heater assembly having a plurality of heater units, each heater unit defining at least one independently controlled heating zone. The heater assembly includes a plurality of power supply leads electrically connected to the heater unit. The heater system includes at least one power switch disposed proximate the heater assembly. The heater system includes at least one controller configured to provide control signals to the at least one power switch such that the power switch modulates power to the independently controlled heating zones via supply conductors based on at least one of heating conditions and heating requirements to provide a desired power output along a length of the heater assembly.

In a variation of this embodiment, the following may be implemented individually or in any combination: the heater system comprises means for determining a temperature; the heater system includes means to determine heating conditions or heating requirements; a heat sink is disposed proximate to the at least one power switch.

The invention also provides an apparatus for heating a fluid. The device includes a sealed housing defining an interior cavity and having a fluid inlet and a fluid outlet. The apparatus includes a heater system including a heater assembly. The heater assembly includes a plurality of heater units, each heater unit defining at least one independently controlled heating zone. The heater assembly includes a plurality of power supply leads electrically connected to the heater unit. The heater system includes at least one power switch disposed proximate the heater assembly. The heater system includes at least one controller configured to modulate power through the power supply leads to the independently controlled heating zones of the heater unit based on at least one of heating conditions and heating requirements to provide a desired power output along the length of the heater assembly. The controller is configured to provide power to the at least one power switch. The heater assembly is disposed within the interior cavity of the housing and is adapted to provide a predetermined thermal profile to the fluid within the housing.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

In order that the invention may be well understood, various forms thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a heater bundle constructed in accordance with the teachings of the present invention;

FIG. 2 is a perspective view of a heater assembly of the heater bundle of FIG. 1 in accordance with the teachings of the present invention;

FIG. 3 is a perspective view of a variation of the heater assembly of the heater bundle of FIG. 1 in accordance with the teachings of the present invention;

FIG. 4 is a perspective view of the heater assembly of FIG. 3 with the outer jacket of the heater assembly removed for clarity in accordance with the teachings of the present invention;

FIG. 5 is a perspective view of a core of the heater assembly of FIG. 3 in accordance with the teachings of the present invention;

FIG. 6 is a perspective view of a heat exchanger including the heater bundle of FIG. 1, with the heater bundle partially detached from the heat exchanger to expose the heater bundle for illustration purposes, in accordance with the teachings of the present invention;

FIG. 7 is a block diagram of a method of operating a heater system including a heater bundle constructed in accordance with the teachings of the present invention;

FIG. 8 is a perspective view of a heat exchanger including the heater bundle, jacket and thermostat of FIG. 1 in accordance with the teachings of the present invention;

FIG. 9 is a block diagram of an enclosure and a thermostat according to the teachings of the present invention;

FIG. 10 is a block diagram of a plurality of power switch networks disposed within an enclosure and proximate to one or more heater assemblies in accordance with the teachings of the present invention; and

figure 11 is a block diagram of an enclosure and a thermostat according to the teachings of the present invention.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

Detailed Description

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Referring to FIG. 1, a heater system constructed in accordance with the teachings of the present invention is generally indicated by reference numeral 10. The heater system 10 includes a heater bundle 12 and a power supply device 14 electrically connected to the heater bundle 12. The power supply device 14 includes a controller 15 for controlling the supply of energy to the heater bundle 12. As used in the present invention, "heater bundle" refers to a heater apparatus comprising two or more physically distinct heating devices that may be independently controlled. Thus, when one of the heating devices in the heater bundle fails or deteriorates, the remaining heating devices in the heater bundle 12 may continue to operate.

In one embodiment, the heater bundle 12 includes a mounting flange 16 and a plurality of heater assemblies 18 secured to the mounting flange 16. The mounting flange 16 includes a plurality of apertures 20 through which the heater assembly 18 extends. Although the heater assemblies 18 are arranged in parallel in this embodiment, it should be understood that alternative locations/arrangements of the heater assemblies 18 are also within the scope of the present invention.

As further shown, the mounting flange 16 includes a plurality of mounting holes 22. The mounting flange 16 may be fitted to the wall of a vessel or pipe (not shown) carrying the fluid to be heated by the use of screws or bolts (not shown) passing through the mounting holes 22. In this embodiment of the invention, at least a portion of the heater assembly 18 is immersed in the fluid inside the vessel or pipe to heat the fluid.

Referring to fig. 2, the heater assembly 18 according to one embodiment may be in the form of a cartridge heater 30. The cartridge heater 30 is a tubular heater that generally includes a core 32, an electrical resistance heater wire 34 wrapped around the core 32, a metal sheath 36 encasing the core 32 and electrical resistance heater wire 34, and an insulating material 38. An insulating material 38 fills the space in the metal sheath 36 to electrically isolate the resistance heating wire 34 from the metal sheath 36 and thermally conduct heat from the resistance heating wire 34 to the metal sheath 36. The core 32 may be made of ceramic. The insulating material 38 may be compacted magnesium oxide (MgO). A plurality of power supply wires 42 extend through the core 32 in the longitudinal direction and are electrically connected to the resistance heating wire 34. The power conductor 42 also extends through an end piece 44 of the sealed metal sheath 36. The power supply lead 42 is connected to the power supply device 14 (shown in fig. 1) to supply power from the power supply device 14 to the resistance heating wire 34. Although fig. 2 shows only two power supply wires 42 extending through the end piece 44, more than two power supply wires 42 may extend through the end piece 44. The power supply leads 42 may be in the form of thermally conductive pins. Various configurations and additional structural and electrical details of cartridge heaters are set forth in more detail in U.S. patent nos. 2,831,951 and 3,970,822, which are commonly assigned with the present application and the contents of which are incorporated herein by reference in their entirety. Accordingly, it should be understood that the forms described herein are illustrative only and are not to be construed as limiting the scope of the invention.

Alternatively, a plurality of resistance heating wires 34 and pairs of power supply leads 42 may be used to form a plurality of heating circuits that can be independently controlled to improve the reliability of the cartridge heater 30. Thus, when one of the resistance heating wires 34 fails, the remaining resistance heating wires 34 can continue to generate heat without causing the entire cartridge heater 30 to fail and without causing costly downtime.

Referring to fig. 3 to 5, the heater assembly 50 may be in the form of a cartridge heater having a similar configuration to that of fig. 2 except that the number of cores and the number of power supply leads used are different. More specifically, each heater assembly 50 includes a plurality of heater units 52, and an outer metal sheath 54 enclosing the plurality of heater units 52 and a plurality of power supply leads 56 therein. An insulating material (not shown in fig. 3-5) is disposed between the plurality of heater cells 52 and the outer metal sheath 54 to electrically isolate the heater cells 52 from the outer metal sheath 54. Each heater unit 52 includes a core 58 and a resistive heating element 60 surrounding the core 58. The resistive heating elements 60 of each heater unit 52 may define one or more heating circuits to define one or more heating zones 62.

In the present embodiment, each heater unit 52 defines one heating zone 62, and the plurality of heater units 52 in each heater assembly 50 are aligned along the longitudinal direction X. Accordingly, each heater assembly 50 defines a plurality of heating zones 62 aligned along the longitudinal direction. The core 58 of each heater unit 52 defines a plurality of through holes 64 to allow the electrical supply leads 56 to extend through the through holes 64. The resistive heating element 60 of the heater unit 52 is connected to the power supply lead 56, which power supply lead 56 is in turn connected to the power supply device 14. The power supply leads 56 supply power from the power supply 14 to the plurality of heaters 52. By properly connecting the power supply leads 56 to the resistive heating elements 60, the resistive heating elements 60 of the plurality of heater units 52 may be independently controlled by the controller 15 of the power supply device 14. Thus, failure of one resistive heating element 60 for a particular heating zone 62 will not affect the proper operation of the remaining resistive heating elements 60 for the remaining heating zones 62. In addition, heater unit 52 and heater assembly 50 may be interchangeable for ease of maintenance or assembly.

In this embodiment, six power conductors 56 are used for each heater assembly 50 to power five separate electrical heating circuits on five heater units 52. Alternatively, six power supply leads 56 may be connected to the resistive heating element 60 in a manner to define three completely independent circuits on the five heater units 52. There may be any number of power conductors 56 to form any number of independently controlled heating circuits and independently controlled heating zones 62. For example, seven power supply leads 56 may be used to provide six heating zones 62. Eight power supply wires 56 may be used to provide seven heating zones 62.

The power conductor 56 may include multiple power and return conductors, multiple return conductors and a single power conductor, or multiple power conductors and a single return conductor. If the number of heating zones is n, the number of supply and return electrical leads is n + 1.

Alternatively, a greater number of electrically distinct heating zones 62 are created by the controller 15 of the power supply device 14 through multiplexing, polarity sensing switches, and other circuit topologies. Cartridge heaters having six power supply leads for a given number of power supply leads (e.g., for 15 or 30 zones) are disclosed in U.S. patent nos. 9,123,755, 9,123,756, 9,177,840, 9,196,513 and related applications, which are commonly assigned with the present application and the contents of which are incorporated herein by reference in their entirety.

With this configuration, each heater assembly 50 includes multiple heating zones 62, which heating zones 62 can be independently controlled to vary the power output or thermal profile along the length of the heater assembly 50. The heater bundle 12 includes a plurality of such heater assemblies 50. Thus, the heater bundle 12 provides multiple heating zones 62 and tailored heat distribution for heating fluid flowing through the heater bundle 12 to suit a particular application. The power supply device 14 may be configured to modulate power to each of the independently controlled heating zones 62.

For example, the heating assembly 50 may define "m" heating zones, and the heater beam may include "k" heating assemblies 50. Thus, the heater beam 12 may define m × k heating zones. The multiple heating zones 62 in the heater bundle 12 may be individually and dynamically controlled in response to heating conditions and/or heating requirements, including but not limited to, the service life and reliability of the individual heater units 52, the size and cost of the heater units 52, the local heater flux, characteristics and operation of the heater units 52, and the overall power output.

Each circuit or selected heating zone is individually controlled at a desired temperature or a desired power level such that the distribution of temperature and/or power accommodates changes in system parameters (e.g., manufacturing variations/tolerances, changing environmental conditions, changing inlet flow conditions, e.g., inlet temperature distribution, flow rate, velocity distribution, fluid composition, fluid heat capacity, etc.). More specifically, due to manufacturing variations and varying degrees of heater degradation over time, the heater units 52 do not produce the same heat output when operated at the same power level. The heater units 52 may be independently controlled to adjust the heat output according to a desired heat profile. The individual manufacturing tolerances of the components of the heater system and the assembly tolerances of the heater system increase with the modulated power of the power supply, or in other words, the manufacturing tolerances of the individual components do not have to be as tight/narrow due to the high fidelity of the heater control.

Each heater cell 52 may include a temperature sensor (not shown) for measuring the temperature of the heater cell 52. When a hot spot in a heater unit 52 is detected, the power supply device 14 may reduce or shut off the power to the heater unit 52 on which the hot spot was detected to avoid overheating or failure of the particular heater unit 52. The power supply device 14 may modulate the energy supply to heater cells 52 adjacent to the disabled heater cell 52 to compensate for the reduced heat output from the particular heater cell 52.

The power supply device 14 may include a multi-zone algorithm to turn off or reduce the power level delivered to any particular zone and increase the power to the heating zones adjacent to the particular heating zone that is disabled and has reduced heat output. By carefully modulating the power to each heating zone, the overall reliability of the system can be improved. By detecting hot spots and controlling the energy supply accordingly, the heater system 10 has improved safety.

Improved heating may be achieved with a heater bundle 12 having multiple independently controlled heating zones 62. For example, some circuits on the heater unit 52 may operate at a nominal (or "typical") duty cycle that is less than 100% (or at an average power level that is a fraction of the heater-generated energy that is applied to the line voltage). The lower duty cycle allows the use of larger diameter resistance heating wires, thereby improving reliability.

Generally, smaller areas will use thinner wire sizes to achieve a given resistance. Variable power control allows for the use of larger wire sizes and can accommodate lower resistance values while protecting the heater from overload by duty cycle limitations associated with the power dissipation capability of the heater.

The use of a scaling factor may be associated with the capacity of the heater unit 52 or the heating zone 62. The multiple heating zones 62 allow for more accurate determination and control of the heater beam 12. A particular heating circuit/zone will allow for more aggressive (i.e., higher) temperatures (or power levels) at nearly all zones, which in turn results in a smaller, less costly design of the heater bundle 12. Such a scale factor and method is disclosed in U.S. patent No.7,257,464, which is commonly assigned with the present application and the contents of which are incorporated herein by reference in its entirety.

The size of the heating zones controlled by the individual circuits can be made equal or different to reduce the total number of zones required to control the distribution of temperature or power to the required accuracy.

Referring to fig. 1, the heater assembly 18 is shown as a single-ended heater, i.e., a heat transfer pin extends through only one longitudinal end of the heater assembly 18. The heater assembly 18 may extend through a mounting flange 16 or bulkhead (not shown) and seal to the flange 16 or bulkhead. Thus, the heater assembly 18 may be removed and replaced separately without removing the mounting flange 16 from the vessel or tube.

Alternatively, the heater assembly 18 may be a "double ended" heater. In the double-ended heater, the metal sheath is bent into a hairpin shape, and the power supply leads are passed through both longitudinal ends of the metal sheath, so that both longitudinal ends of the metal sheath are passed through and sealed to the flange or the partition. In such a configuration, the flange or baffle would need to be removed from the housing or vessel before the individual heater assemblies 18 could be replaced.

Referring to fig. 6, the heater bundle 12 is incorporated into a heat exchanger 70. The heat exchanger 70 includes a sealed housing 72 defining an interior cavity (not shown), the heater bundle 12 being disposed within the interior cavity of the housing 72. The sealed housing 72 includes a fluid inlet 76 and a fluid outlet 78, and fluid flows into the interior of the sealed housing 72 and out of the interior of the sealed housing 72 through the fluid inlet 76 and the fluid outlet 78. The fluid is heated by the heater bundle 12 disposed in the sealed enclosure 72. The heater bundle 12 may be arranged for cross flow or flow parallel to its length.

The heater bundle 12 is connected to a power supply means 14, which power supply means 14 may comprise means for modulating the power, such as switching means or variable transformers, to modulate the power supplied to the individual zones. The power modulation may be performed as a function of time or based on the detected temperature of each heating zone.

The resistance heating wire may also function as a sensor, using the resistance of the resistance wire to measure the temperature of the resistance wire, and using the same power supply leads to send the temperature measurement information to the power supply device 14. The means of sensing the temperature of each zone will allow the temperature to be controlled along the length (down to the resolution of the individual zones) of each heater assembly 18 in the heater bundle 12. Therefore, an additional temperature sensing circuit and sensing device can be omitted, thereby reducing manufacturing costs. Directly measuring heater circuit temperature is a significant advantage when attempting to maximize heat flux in a given circuit while maintaining the required level of reliability of the system, as it eliminates or minimizes many of the measurement errors associated with using separate sensors. The heating element temperature is the characteristic that has the greatest influence on the reliability of the heater. The use of a resistive element to function as both a heater and a sensor is disclosed in U.S. patent No.7,196,295, which is commonly assigned with the present application and the contents of which are incorporated herein by reference in its entirety.

Alternatively, the power supply leads 56 may be made of different kinds of metals, so that the different kinds of metal power supply leads 56 may produce a thermocouple for measuring the temperature of the resistance heating element. For example, at least one set of power and return leads may comprise different materials such that a junction is formed between the different materials and the resistive heating element of the heater unit and used to determine the temperature of one or more zones. The use of "integrated" and "highly thermally coupled" sensing, e.g., using different metals for the heater, results in the generation of a thermocouple-like signal. The use of integrated and coupled power conductors for temperature measurement is disclosed in U.S. application No.14/725,537, which is commonly assigned with the present application and the contents of which are incorporated herein by reference in its entirety.

The controller 15 for modulating the electrical power delivered to each zone may be a closed loop automatic control system. A closed loop automatic control system receives temperature feedback from each zone and automatically and dynamically controls power delivery to each zone, thereby automatically and dynamically controlling power distribution and temperature along the length of each heater assembly 18 in the heater bundle 12 without the need for continuous or frequent manual monitoring and adjustment.

The heater units 52 as disclosed herein may also be calibrated using a variety of methods, including but not limited to energizing and sampling each heater unit 52 to calculate its resistance. The calculated resistance may then be compared to a calibrated resistance to determine a resistance ratio, or to a value and then the actual heater unit temperature determined. Exemplary methods are disclosed in U.S. patent nos. 5,280,422 and 5,552,998, which are commonly assigned with the present application and the contents of which are incorporated herein by reference in their entirety.

One form of calibration includes operating the heater system 10 in at least one mode of operation, controlling the heater system 10 to produce a desired temperature for at least one of the independently controlled heating zones 62, collecting and recording the at least one independently controlled heating zone 62 for the mode of operation, then accessing the recorded data to determine operating specifications for the heating system having a reduced number of independently controlled heating zones, and then using the heating system having a reduced number of independently controlled heating zones. For example, the data may include power level and/or temperature information, as well as other operational data from the heater system 10 for which data is collected and recorded.

In variations of the present invention, the heater system may include a single heater assembly 18 rather than a plurality of heater assemblies in the heater bundle 12. The unitary heater assembly 18 includes a plurality of heater units 52, each heater unit 52 defining at least one independently controlled heating zone. Similarly, the power supply lead 56 is electrically connected to each independently controlled heating zone 62 in each heater unit 52, and the power supply device is configured to modulate power to each independently controlled heating zone 62 of the heater unit via the power supply lead 56.

Referring to fig. 7, a method 100 of controlling a heater system includes providing a heater bundle including a plurality of heater assemblies in step 102. Each heater assembly includes a plurality of heater cells. Each heater unit defines at least one independently controlled heating circuit (and thus heating zone). In step 104, power is supplied to each heater unit through power supply leads electrically connected to each independently controlled heating zone in each heater unit. In step 106, the temperature within each zone is detected. The temperature may be determined using a change in resistance of the resistive heating element of the at least one heater unit. The zone temperature may be determined initially by measuring the zone resistance (or, if a suitable material is used, by measuring the circuit voltage).

The temperature values may be digitized. The signal may be communicated to a microprocessor. In step 108, the measured (detected) temperature values may be compared to a target (desired) temperature for each zone. Based on the measured temperatures, the power supplied to each heater unit may be modulated to achieve a target temperature in step 110.

Optionally, the method may further comprise adjusting the modulation power using a scaling factor. The scaling factor may be a function of the heating capacity of each heating zone. The controller 15 may include an algorithm, potentially including a scaling factor and/or mathematical model of the dynamic behavior of the system (including knowledge of the system update time) to determine the amount of power to be provided (by duty cycle, phase angle triggering (ringing), voltage modulation, or similar techniques) to each zone until the next update. The desired power may be converted to a signal that is sent to a switch or other power modulation device to control the power output to the individual heating zones.

In this embodiment, when at least one heating zone is turned off due to an abnormal condition, the remaining zones continue to provide the required power (watts) without failure. When an abnormal condition is detected in at least one of the heating zones, power is modulated to the functional heating zone to provide the desired power. When at least one of the heating zones is turned off based on the determined temperature, the remaining zones continue to provide the required power. Power is modulated to each heating zone according to the received signal, the model, and according to time.

For safety or process control reasons, a typical heater is typically operated below a maximum allowable temperature to prevent a particular location of the heater from undesirable chemical or physical reactions (e.g., combustion/fire/oxidation, coker boil, etc.) occurring at the particular location. Thus, this is typically accommodated by a conservative heater design (e.g., a large heater with a low power density and a large portion of its surface area loaded with a much lower heat flux than would otherwise be possible).

However, with the heater bundle of the present invention, the temperature can be measured and limited anywhere within the heater, and limited to a resolution on the order of the size of the individual heating zones. Hot spots large enough to affect the temperature of the individual circuits can be detected.

Since the temperature of the individual heating zones can be automatically adjusted and therefore limited, the dynamic and automatic limiting of the temperature of each zone will keep that zone and all other zones operating at the optimum power/heat flux level without fear of exceeding the temperature limit required at any zone. This provides the advantage of high upper temperature measurement accuracy compared to the current practice of clamping individual thermocouples to the sheath of one element in the bundle. The reduced margin and the ability to modulate power to individual zones may be selectively and individually applied to the heating zones, selectively and individually, rather than to the entire heater assembly, thereby reducing the risk of exceeding a predetermined upper temperature limit.

The characteristics of the cartridge heater may change over time. In addition, such time-varying characteristics would require cartridge heaters to be designed for a single selected (worse case) flow regime, and thus, the cartridge heater would operate at a sub-optimal state for the other flow regime.

However, due to the provision of multiple heating elements in the heater assembly, by dynamically controlling the power distribution across the bundle up to the resolution of the core size, an optimized power distribution for various flow conditions can be achieved, rather than just one power distribution corresponding to just one flow condition in a typical cartridge heater. Thus, the heater bundle of the present application allows for an increase in the total heat flux for all other flow conditions.

In addition, variable power control may increase flexibility in heater design. In heater design, the voltage can be (largely) decoupled from the resistance and the heater can be designed to have the largest wire diameter that can fit into the heater. It allows for increased power dissipation capability for a given heater size and reliability level (or service life of the heater) and for a reduced beam size at a given total power level. The power in such an arrangement may be modulated by a variable duty cycle that is part of a currently available or developing variable power controller. The heater bundle can be protected by a programmable (or preprogrammed, if desired) upper limit on the duty cycle of a given zone to prevent "overloading" of the heater bundle.

Referring to fig. 8, the heater system 10 as described above is incorporated into an example application of a heat exchanger 70. It should be understood that the application of the heat exchanger 70 is merely exemplary and should not be construed as limiting the application of the present invention. As shown, the heater system 10 includes at least one power switch 120 (shown schematically) disposed proximate to the heater bundle 12 or near the heater bundle 12. The controller 15 is configured to provide control signals to the power switch 120 such that the independently controlled heating zones are modulated in power by the supply conductor pair based on a predetermined temperature to provide a desired power output along the length of the at least one heater assembly 50.

Because the power switch 120 is near the heater bundle 12 or in the vicinity of the heater bundle 12, the number of individual insulated wires extending from the remote location/cabinet to the heater bundle 12 can be significantly reduced as opposed to being located at the remote location/cabinet. Further, depending on the type of power source used (e.g., direct current, single phase alternating current, three phase alternating current, and three phase alternating current with common and/or ground conductors, etc.), the integrated switch of the heater assembly 18 may reduce the number of conductors.

In one embodiment, the power switch is disposed within the enclosure 200, and the power leads 56 are elongated outside the confines of the heater assembly 18 to extend into the enclosure 200 that is physically connected to the power switch 120. In one variation of the physical connection, for a "plug-in" type connection, the power conductor 56 may form a pin or socket shape, while the mating power switch forms a socket or pin shape, respectively. An optional thermostat 300 (also shown schematically) may be used to provide cooling to the jacket 200. The enclosure 200 may be implemented in various designs/geometries (e.g., junction box, terminal enclosure 200, etc.) configured to enclose one or more electronic devices, including but not limited to power switch 120, controller 15 or other controller, associated electronics, and/or wireless communication components, etc. Using wireless means, the controller 15 can be remote from the heater bundle 12 and in remote communication with the power switch 120. The controller 15 may also be remote and communicate with the power switch 120 through the power conductor 56. In one embodiment, the envelope 200 is sealed such that the components therein are protected from moisture ingress and are sealed from the outside atmosphere. Further, the enclosure 200 protects the internal components from damage during installation/operation/maintenance.

The temperature adjustment device 300 may be implemented by any device/system configured to control the temperature of the envelope 200. For example, cooling may be provided by a liquid (e.g., a heat sink) or a pressurized airflow, and the pressurized airflow may be located inside the enclosure 200 or outside the enclosure 200. In one variation, the jacket 200 is cooled by an inner fluid cooling stream and an outer fluid cooling stream, each cooling stream being coupled by a heat exchanger. In yet another variation, the enclosure 200 is cooled by at least one of a thermoelectric element and a refrigeration system. In yet another embodiment, a heat sink (e.g., extruded aluminum fins) may be used near power switch 120 or near power switch 120, either alone or in conjunction with thermostat 300. Further details of the exemplary thermostat 300 are described in more detail below.

Referring to fig. 9, an auxiliary heat exchanger 300-1 (as a thermostat 300) and an envelope 200-1 are shown in schematic form. In this embodiment, the auxiliary heat exchanger 300-1 includes a housing 308, an aperture 310, a fan drive 312, a fan 314, and a chamber 316.

The enclosure 200-1 includes an interface surface 202, a set of conductor holes 204 (shown as separate holes for ease of illustration) extending through the thickness of a housing 208, a chamber 210 defined by the housing 208, a vent hole 214, and an outlet hole 216. In one embodiment, the enclosure 200-1 includes one or more power switches 212 and a controller 213 disposed within the chamber 210. As enumerated above, an optional heat sink 215 is disposed proximate the power switch 212 to draw heat away from the power switch 212. In one embodiment, the controller 213 is configured in a similar manner to the controller 15 when determining control signals to provide the power switches 212 to the various zones (via duty cycle, phase angle triggering, voltage modulation, or similar techniques). As enumerated above, the enclosure 200-1 (and thus the power switch 212) is disposed proximate (e.g., adjacent and/or near) one or more heater assemblies 18 of the heater bundle 12.

In one embodiment, the one or more power switches 212 are electrically coupled to the controller 213 and include, for example, Bipolar Junction Transistors (BJTs), Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs), addressable switches, operational amplifiers, transistor drivers, integrated circuits, combinations thereof, and/or the like. In some forms, the number of power switches 212 corresponds to the number of heating zones 62 of the respective heater assembly 18. By way of example, as shown in FIG. 10, each heater assembly 18 includes n heating zones. Accordingly, the power switches 212-1, 212-2, 212-3, 212-4, 212-5, 212-6 each include n power switches arranged in parallel to selectively and independently provide power to the corresponding heating zones 62 of the heater assembly 18. It should be understood that in other embodiments, each of the power switches 212-1, 212-2, 212-3, 212-4, 212-5, 212-6 may have other numbers and/or types of power switches to selectively and independently provide power to the respective heating zones 62 of the heater assembly 18, and is not limited to the examples described herein.

With continued reference to FIG. 10, the controller 213 is configured to selectively activate (or send control signals to) the one or more power switches 212 to thereby selectively activate one or more of the heating zones 62 of the at least one heater assembly 18. In one embodiment, controller 213 is configured to activate one or more power switches 212 to allow power from power supply 14 to be provided to heater assembly 18. As an example, to activate the power switches 212 (e.g., one or more BJTs), the controller 213 is configured to selectively provide a bias voltage to the one or more power switches 212. To perform the functions described herein, the controller 213 may be implemented by a microcontroller including one or more processor circuits configured to execute machine-readable instructions stored in one or more non-transitory computer-readable media, such as Random Access Memory (RAM) circuits and/or Read Only Memory (ROM) circuits. In addition, the controller 213 may include one or more voltage drivers for providing bias voltages to the one or more power switches 212.

Although the controller 213 is shown as being disposed within the chamber 210, in other embodiments, the controller 213 may be located outside of the chamber 210. Accordingly, the enclosure 200-1 may include a wireless communication circuit that enables the controller 213 to activate one or more power switches 212, and the controller 213 may communicate with the wireless communication circuit via a wireless communication link (e.g., a bluetooth communication link, a Near Field Communication (NFC) link, an ultra-wideband (UWB) communication link, a wireless fidelity (WiFi) communication link, a Zigbee communication link, a cellular communication link, a Long Term Evolution (LTE) communication link, a 5G communication link, and/or other similar wireless communication links). Further, in one embodiment, the enclosure 200-1 includes an additional power supply system (e.g., an additional power supply and one or more power regulator circuits) that is external to the enclosure 200-1 at the controller 213 and that is electrically coupled to the wireless communication circuit and the one or more power switches 212 when the one or more power switches 212 are not connected to the power device 14. Accordingly, the additional power supply system is configured to provide power to the one or more power switches 212 to selectively activate the one or more power switches 212 in response to the power supply wireless communication circuit receiving a signal from the controller 213.

Although the controller 213 and the controller 15 are illustrated and described as separate components, it should be understood that the functions of the controller 213 may be performed by the controller 15 in other forms, and vice versa.

In one embodiment, and referring to FIG. 9, the auxiliary heat exchanger 300-1 may be an air-cooled heat exchanger that uses a pressurized airflow to cool the jacket 200-1 and components therein. While the auxiliary heat exchanger 300-1 is illustrated as using a pressurized airflow to cool the jacket 200-1 and components therein, it should be understood that the auxiliary heat exchanger 300-1 may be an induced air cooled heat exchanger in other variations.

In one embodiment, air flows into chamber 316. In response to activation by the fan drive 312, the fan 314 forces air toward the outer surface of the housing 308, as indicated by the dashed arrows in FIG. 9. In addition, as shown by the dashed arrows in FIG. 9, the fan 314 forces air into the chamber 210 through the vents 214 to reduce the temperature of the components within the enclosure 200-1. Air forced into the vents 214 of the chamber 210 may exit the enclosure 200-1 via the outlet holes 216. Although fig. 9 illustrates one vent hole 214 and one exit hole 216, it should be understood that any number of vent holes 214 and exit holes 216 may be included in other variations of the invention. Further, the vent 214 and the outlet aperture 216 may be positioned at different locations of the housing 208 and are not limited to the specific illustrations herein.

In one embodiment, the fan driver 312 includes one or more controllers, integrated circuits, power regulator circuits, and discrete electrical components configured to activate the fan 314. In one embodiment, the fan drive 312 is electrically coupled to the power supply device 14 via a hard-wired link (e.g., twisted pair cable) disposed at least partially in the aperture 310. As an example, the fan driver 312 activates the fan 314 in response to receiving power from the power supply device 14.

Referring to fig. 11, a heat exchanger 300-2 and an envelope 200-2 as a thermostat 300 are shown. The enclosure 200-2 is similar to the enclosure 200-1 described above, but in this embodiment, the enclosure 200-2 does not include the vent 214 and the outlet aperture 216. Thus, the envelope 200-2 is isolated from the heat exchanger 300-2.

In one embodiment, heat exchanger 300-2 defines an inner fluid system and an outer fluid system, and heat exchanger 300-2 includes an outer fluid inlet 320, an outer fluid outlet 322, an inner fluid inlet 326, an inner fluid outlet 328, an inlet plenum 330, an outlet plenum 332, a tubesheet 334, one or more inner fluid conduits, one or more baffles 338, a shell 340, and a chamber 342. In one embodiment, the heat exchanger 300-2 is configured as a U-tube heat exchanger. It should be understood that the heat exchanger 300-2 can have various other configurations in other forms (e.g., a floating head heat exchanger, a straight tube heat exchanger, etc.) and is not limited to the configurations described herein.

The heat exchanger 300-2 is configured to reduce the temperature of the envelope 200-2 via fluid flowing through the internal fluid system and the external fluid system. Specifically, the fluid (e.g., gas, water, coolant, etc.) flowing through the heat exchanger 300-2 absorbs heat from the envelope 200-2, thereby lowering the temperature of the envelope 200-2.

In one embodiment, the internal fluid system is provided by the internal fluid conduit 336, the inlet plenum 330, the internal fluid inlet 326, and one or more apertures of the tubesheet 334 disposed in a chamber 342 within the housing 340. After operation, fluid flows through the inner fluid inlet 326 and the inlet plenum 330, where it enters the inner fluid conduit 336 via the holes of the tubesheet 334. The fluid passing through the internal fluid system, which may be referred to as the internal fluid, then exits the heat exchanger 300-2, the outlet plenum 332, and the internal fluid outlet 328 via one or more holes of the tube sheet 334.

In one embodiment, the external fluid system is disposed about the internal fluid system within chamber 342 and includes baffles 338, external fluid inlets 320, and external fluid outlets 322 extending within chamber 342. During operation, fluid enters chamber 342 via external fluid inlet 320 and flows through chamber 342 according to the flow path defined by the arrangement of baffles 338 and exits the external fluid system via external fluid outlet 322. Fluid flowing through the external fluid system may be referred to as external fluid. In one embodiment, one or more pumps, conduits, and reservoirs (not shown) are fluidly coupled to the heat exchanger 300-2 to regulate the flow of internal fluid into the heat exchanger 300-2 and external fluid out of the heat exchanger 300-2.

Unless otherwise expressly stated herein, all numbers indicating mechanical/thermal properties, compositional percentages, dimensions, and/or tolerances, or other characteristics, are to be understood as modified by the word "about" or "approximately" in describing the scope of the present invention. Such modifications are desirable for a variety of reasons, including industrial practice, materials, manufacturing and assembly tolerances, and testing capabilities.

Various terms (including "connected," "engaged," "coupled," "adjacent," "immediately adjacent," "on top of … …," "above … …," "below … …," and "disposed") are used to describe spatial and functional relationships between elements. Unless explicitly described as "direct," when a relationship between a first element and a second element is described in the present invention, the relationship may be a direct relationship in which no other intermediate element exists between the first element and the second element, and may also be an indirect relationship in which one or more intermediate elements (spatially or functionally) exist between the first element and the second element. As used herein, at least one of the phrases A, B and C should be construed to mean logic (a or B or C) using a non-exclusive logical or and should not be construed to mean "at least one of a, at least one of B, and at least one of C.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A heater system, comprising:

a heater bundle comprising:

at least one heater assembly comprising a plurality of heater units, more than one of the heater units defining at least one independently controlled heating zone;

a plurality of power supply leads electrically connected to the independently controlled heating zones;

means for determining a temperature;

at least one power switch disposed proximate to the heater bundle; and

at least one controller configured to provide control signals to the at least one power switch such that the power switch modulates power to the independently controlled heating zones through the power supply leads based on the determined temperature to provide a desired power output along the length of the at least one heater assembly.

2. The heater system according to claim 1, further comprising an enclosure, wherein the at least one power switch is disposed within the enclosure.

3. The heater system according to claim 2, further comprising a temperature regulating device that cools the jacket.

4. The heater system according to claim 3, wherein the temperature regulating device cools the jacket using a liquid cooling medium.

5. The heater system according to claim 3, wherein the temperature regulating device uses a pressurized airflow to cool the jacket.

6. The heater system according to claim 5, wherein the pressurized airflow is provided inside the enclosure and outside the enclosure.

7. The heater system according to claim 3, wherein the envelope is sealed from the outside atmosphere.

8. The heater system according to claim 7, wherein the temperature regulating device cools the jacket using an internal fluid cooling flow and an external fluid cooling flow, each of the cooling flows being coupled through a heat exchanger.

9. The heater system according to claim 3, wherein the temperature regulating device is at least one of a thermoelectric element and a refrigeration system.

10. The heater system according to claim 2, wherein the at least one controller is disposed within the enclosure.

11. The heater system according to claim 1, wherein the at least one controller is remote from the heater bundle and communicates with the at least one power switch wirelessly and/or through the plurality of power conductors.

12. The heater system according to claim 1, further comprising a heat sink disposed proximate to the at least one power switch.

13. A heater system, comprising:

a heater bundle comprising:

means for determining at least one of heating conditions and heating requirements;

at least one power switch disposed proximate to the heater bundle; and

at least one controller configured to provide control signals to the at least one power switch such that the power switch modulates power to the independently controlled heating zones via the supply conductors based on at least one of heating conditions and heating requirements to provide a desired power output along a length of the at least one heater assembly.

14. The heater system according to claim 13, further comprising an enclosure disposed proximate the plurality of heater assemblies, wherein the at least one power switch is disposed within the enclosure.

15. The heater system according to claim 14, wherein the at least one controller is disposed within the enclosure.

16. The heater system according to claim 13, wherein the at least one controller is remote from the heater bundle and communicates with the at least one power switch wirelessly and/or through the plurality of power conductors.

17. The heater assembly according to claim 13, wherein the at least one of heating conditions and heating requirements is selected from a group consisting of a lifetime of the heater unit, a reliability of the heater unit, a size of the heater unit, a cost of the heater unit, a local heater flux, characteristics and operation of the heater unit, and an overall power output.

18. The heater system according to claim 13, further comprising a heat sink disposed proximate the at least one power switch.

19. A heater system, comprising:

a heater assembly comprising a plurality of heater units, more than one of the heater units defining at least one independently controlled heating zone;

a plurality of power supply leads electrically connected to the heater unit;

at least one power switch disposed proximate the heater assembly; and

at least one controller configured to provide control signals to the at least one power switch such that the power switch modulates power to the independently controlled heating zones via supply conductors based on at least one of heating conditions and heating requirements to provide a desired power output along a length of the heater assembly.

20. The heater system according to claim 19, further comprising means for determining a temperature.

21. The heater system according to claim 19, further comprising means for determining heating conditions or heating requirements.

22. An apparatus for heating a fluid, comprising:

a sealed housing defining an internal cavity and having a fluid inlet and a fluid outlet; and

the heater system according to claim 19, the heater assembly being disposed within the internal cavity of the housing,

wherein the heater assembly is adapted to provide a predetermined thermal profile to the fluid within the housing.

23. The heater system according to claim 19, further comprising a heat sink disposed proximate the at least one power switch.