KR20220127171A - Heater bundles having variable power output within zones - Google Patents

Abstract

A heater system includes a heater bundle with heater assemblies. At least one of the heater assemblies has a plurality of heater units. At least one heater unit has an independently controlled heating zone. At least one heater assembly has a physical construction configured to deliver a variable output per unit length along the length of at least one heater assembly. A plurality of power conductors are electrically connected to the plurality of heater units, and the heater system further includes a means for determining temperature. A power supply device includes a controller configured to modulate power to the independently controlled heating zone through the power conductors based on a determined temperature to provide a desired output along the length of at least one heater assembly.

Description

HEATER BUNDLES HAVING VARIABLE POWER OUTPUT WITHIN ZONES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Application Serial No. 15/058,838, filed March 2, 2016, and now U.S. Patent No. 10,247,445, entitled “Heater Bundles for Adaptive Control,” filed on February 11, 2019. It is a continuation-in-part of US Application No. 16/272,668. The contents of the above disclosures are incorporated herein by reference in their entirety.

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

The description in this section merely provides 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, which has a rod configuration for heating fluid flowing along or past an outer surface of the cartridge heater. A cartridge heater may be disposed within the heat exchanger to heat a fluid flowing through the heat exchanger. If the cartridge heater is not properly sealed, moisture and fluid can enter the cartridge heater and contaminate the insulating material that electrically insulates the resistive heating element from the metal sheath of the cartridge heater, resulting in dielectric breakdown and consequent heater failure. Moisture can also cause short circuits between the power conductors and the outer metal sheath. Failure of the cartridge heater can stop the device using the cartridge heater, and the downtime is costly.

The present disclosure provides a heater system comprising a heater bundle, the heater bundle comprising a plurality of heater assemblies, at least one of the heater assemblies comprising a plurality of heater units, and at least one heater The unit has an independently controlled heating zone, the at least one heater assembly including a physical construction configured to deliver a variable power output per unit length along a length of the at least one heater assembly. A plurality of power conductors are electrically connected to the plurality of heater units, the heater system further comprising means for determining a temperature. The power supply includes a controller configured to regulate power to the independently controlled heating zone via the power conductors based on a temperature determined to provide a desired power output along a length of the at least one heater assembly. . .

In variants of this heater system, which may be implemented individually or in any combination: the physical configuration comprises a resistive heating element having a variable pitch inside at least one heater unit; the variable pitch continuously varies along the length of the resistive heating element; the physical configuration includes a resistive heating element having a variable cross-sectional area within the at least one heater unit; the physical configuration includes a resistive heating element having a variable cross-sectional area and a variable pitch within the at least one heater unit; the physical configuration includes a plurality of parallel circuits within at least one heater unit; the physical configuration is provided for more than one of the plurality of heater units; the physical configuration comprises an adjacent heater unit or composite heating element having a higher electrical resistivity proximate to an end of the at least one heater assembly and a lower electrical resistivity proximate to an opposing other adjacent heater unit; the physical configuration is provided for more than one of the heater assemblies; at least one heater assembly of the plurality of heater assemblies is a cartridge heater; the physical configuration includes at least one heater unit having a cross-sectional area different from adjacent heater units; the heater units include a plurality of resistive heating elements, at least one of the resistive heating elements functioning as a sensor; the physical configuration includes a composite heating element having a variable electrical resistivity; The variable electrical resistivity includes a higher electrical resistivity proximate to an adjacent heater unit or end of the at least one heater assembly and a lower electrical resistivity proximate to an opposite adjacent heater unit.

In another aspect, a fluid heating device includes a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet, with the heater system described above, the heater bundle being disposed within the inner chamber of the housing. The heater bundle is configured to provide a responsive heat distribution to the fluid within the housing.

In yet another form, a heater system includes a heater bundle comprising a plurality of heater assemblies, wherein at least one of the heater assemblies comprises a plurality of heater units, wherein the at least one heater unit comprises an independently controlled heating zone. wherein the at least one heater assembly includes a physical construction configured to deliver a variable power output per unit length along a length of the at least one heater assembly. A plurality of power conductors are electrically connected to the plurality of heater units, and means are provided for determining at least one of heating conditions and heating requirements. A power supply is configured to provide power to the independently controlled heating zone via the power 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. a controller configured to adjust the

In variants of this heater system, which may be implemented individually or in any combination: at least one of heating conditions and heating requirements is: the lifetime of the heater units, the reliability of the heater units, the size of the heater units; cost of the heater units, heater flux, characteristics and operation of the heater units, power output, power input, and total power output.

In a further variant, the device comprises a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet. The heater assembly is disposed within an interior chamber of the housing and the heater assembly is configured to provide a responsive heat distribution to a fluid within the housing.

In another aspect of the present disclosure, a heater system includes a heater assembly comprising a plurality of heater units, wherein at least one heater unit has an independently controlled heating zone, the heater assembly extending along a length of the heater assembly and a physical construction configured to deliver a variable power output per unit length. A plurality of power conductors are electrically connected to the heater units, wherein the power supply is configured to provide a desired power output along a length of the heater assembly based on at least one of heating conditions and heating requirements. and a controller configured to regulate power to the independently controlled heating zone via

In variants of this heater system, which may be implemented individually or in any combination: means for determining a temperature are provided, and means for determining heating conditions or heating requirements are provided.

In another form of this heater system, a fluid heating device includes a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet, and a heater assembly disposed within the inner chamber of the housing. The heater assembly is configured to provide a responsive heat distribution to a fluid within the housing.

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

In order that the present disclosure may be better understood, various forms, given by way of example, will now be described with reference to the accompanying drawings.
1 is a perspective view of a heater bundle constructed in accordance with the teachings of the present disclosure;
2 is a perspective view of a heater assembly of the heater bundle of FIG. 1 in accordance with the teachings of the present disclosure;
3 is a perspective view of a variant of the heater assembly of the heater bundle of FIG. 1 in accordance with the teachings of the present disclosure;
FIG. 4 is a perspective view of the heater assembly of FIG. 3 in accordance with the teachings of the present disclosure, with the outer covering of the heater assembly removed for clarity;
5 is a perspective view of the core body of the heater assembly of FIG. 3 in accordance with the teachings of the present disclosure;
6 is a perspective view of a heat exchanger including the heater bundle of FIG. 1 in accordance with the teachings of the present disclosure, wherein the heater bundle is partially disassembled from the heat exchanger to expose the heater bundle for illustration purposes;
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 disclosure;
8A is a side view of one form of a heater unit having a variable power output configured in accordance with the teachings of this disclosure;
8B is a side view of another form of a heater unit having a variable power output constructed in accordance with the teachings of this disclosure;
8C is a side view of another form of a heater unit having a variable power output constructed in accordance with the teachings of this disclosure;
8D is a side view of another form of a heater unit having a variable power output configured in accordance with the teachings of this disclosure;
8E is a schematic side view of another form of a heater unit having a plurality of parallel circuits to provide a variable power output in accordance with the teachings of this disclosure;
9 is a perspective view of heater units having different cross-sectional areas and constructed in accordance with the teachings of the present disclosure.
The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.

The following description is merely illustrative in nature and is not intended to limit the disclosure, application or use of the present disclosure.

1 , a heater system constructed in accordance with the teachings of this disclosure is indicated generally by reference numeral 10 . The heater system 10 includes a heater bundle 12 and a power supply 14 electrically connected to the heater bundle 12 . The power supply 14 includes a controller 15 for controlling the power supply to the heater bundle 12 . “Heater bundle”, as used in this disclosure, refers to a heater device comprising two or more physically distinct heating devices that can be controlled independently. Thus, when one of the heating devices in the heater bundle fails or deteriorates, the remaining heating devices in the heater bundle 12 can continue to operate.

In one form, 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 openings 20 through which the heater assemblies 18 extend. Although the heater assemblies 18 are arranged parallel in this configuration, it should be understood that alternative positions/dispositions of the heater assemblies 18 are within the scope of the present disclosure.

As further shown, the mounting flange 16 includes a plurality of mounting holes 22 . By using screws or bolts (not shown) through the mounting holes 22, the mounting flange 16 can be assembled to the wall of a vessel or pipe (not shown) carrying the fluid to be heated. At least a portion of the heater assemblies 18 is immersed in a fluid within a vessel or pipe to heat the fluid in this form of the present disclosure.

Referring to FIG. 2 , the heater assemblies 18 according to one form may be in the form of a cartridge heater 30 . The cartridge heater 30 generally includes a core body 32, a resistive heating wire 34 wound around the core body 32, and a metal sheath surrounding the core body 32 and the resistive heating wire 34 ( 36 ), and insulation filled in the space within the metal sheath 36 to insulate the resistive heating wire 34 from the metal sheath 36 and conduct heat from the resistive heating wire 34 to the metal sheath 36 . A tube-shaped heater comprising material 38 . The core body 32 may be made of ceramic. The insulating material 38 may be compressed magnesium oxide (MgO). A plurality of power conductors 42 extend through the core body 32 along the longitudinal direction and are electrically connected to the resistive heating wire 34 . The power conductors 42 also extend through an end piece 44 sealing the metal sheath 36 . The power conductors 42 are connected to a power supply 14 (shown in FIG. 1 ) to provide power from the power supply 14 to the resistive heating wire 34 . Although FIG. 2 tightens only two power conductors 42 extending through the end piece 44 , more than two power conductors 42 may extend through the end piece 44 . The power conductors 42 may be in the form of conductive pins. Various configurations of cartridge heaters and additional structural and electrical details are set forth in greater detail in US Pat. Nos. 2,831,951 and 3,970,822, which are jointly incorporated herein by reference, the contents of which are incorporated herein by reference in their entirety. incorporated by reference. Accordingly, the forms shown herein are illustrative only and should not be construed as limiting the scope of the present disclosure.

Alternatively, multiple pairs of resistive heating wires 34 and multiple power conductors 42 can be used to form multiple heating circuits that can be independently controlled to improve the reliability of cartridge heater 30 . have. Thus, when one of the resistive heating wires 34 fails, the remaining resistive heating wires 34 continue to heat without causing failure of the entire cartridge heater 30 and costly machine downtime. can cause

3 to 5 , the heater assemblies 50 may be in the form of a cartridge heater having a configuration similar to that of FIG. 2 except for the number of core bodies and the number of power conductors used.

More specifically, each of the heater assemblies 50 has an outer metal sheath 54 surrounding the plurality of heater units 52 together with the plurality of heater units 52 and the plurality of power conductors 56 . include An insulating material (not shown in FIGS. 3-5 ) is provided between the plurality of heater units 52 and the outer metal sheath 54 to electrically insulate the heater units 52 from the outer metal sheath 54 . . The plurality of heater units 52 each include a core body 58 and a resistive heating element 60 surrounding the core body 58 . The resistive heating element 60 of each heater unit 52 may form one or more heating circuits to form one or more heating zones 62 .

In this form, each heater unit 52 forms one heating zone 62 and a plurality of heater units 52 in each heater assembly 50 are aligned along the longitudinal direction X. Thus, each heater assembly 50 defines a plurality of heating zones 62 aligned along the longitudinal direction X. The core body 58 of each heater unit 52 defines a plurality of through holes/openings 64 through which the power conductors 56 extend. The resistive heating elements 60 of the heater units 52 are connected to power conductors 56 , which in turn are connected to a power supply 14 . The power conductors 56 supply power from the power supply 14 to the plurality of heater units 52 . By properly connecting the power conductors 56 to the resistive heating elements 60 , the resistive heating elements 60 of the plurality of heater units 52 are connected to the controller 15 of the power supply 14 . can be independently controlled by As such, failure of one resistive heating element 60 for a particular heating zone 62 will not affect the proper functioning of the remaining resistive heating elements 60 for the other heating zones 62 . In addition, the heater units 52 and the heater assemblies 50 may be interchangeable for ease of maintenance or assembly.

In this form, six power conductors 56 are used in each heater assembly 50 to power five independent electrical heating circuits on the five heater units 52 . Alternatively, the six power conductors 56 may be connected to the resistive heating elements 60 in a manner that forms three completely independent circuits in the five heater units 52 . It may have 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 conductors 56 may be used to provide six heating zones 62 . Eight power conductors 56 may be used to provide seven heating zones 62 .

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

Alternatively, a greater number of electrically distinct heating zones via multiplexing, polarity sensitive switching, and other circuit topologies by the controller 15 of the power supply 14 Fields 62 may be created. Thermal arrays ( The use of various arrangements or multiplexing of thermal arrays is disclosed in US Pat. Nos. 9,123,755, 9,123,756, 9,177,840, 9,196,513, and related applications thereof, which are jointly incorporated herein by reference. Their contents are hereby incorporated by reference in their entirety.

With this structure, each heater assembly 50 includes a plurality of heating zones 62 that can be independently controlled to vary the power output or heat distribution along the length of the heater assembly 50 . The heater bundle 12 includes a plurality of such heater assemblies 50 . Accordingly, the heater bundle 12 provides a plurality of heating zones 62 for heating the fluid flowing through the heater bundle 12 and a tailored heat distribution to be tailored to specific applications. The power supply 14 may be configured to regulate power to each of the independently controlled heating zones 62 .

For example, the heater assembly 50 may define “m” heating zones, and the heater bundle may include “k” heater assemblies 50 . Thus, the heater bundle 12 can form m*k heating zones. The plurality of heating zones 62 in the heater bundle 12 are based on the lifetime and reliability of the individual heater units 52 , the size and cost of the heater units 52 , the local heater flux, and the heater units 52 . ) can be individually and dynamically controlled in response to heating conditions and/or heating requirements including, but not limited to, operation, power output, power input, and total power output.

Each circuit, or selected heating zone, is dependent on the power and/or temperature distribution of changes in system parameters (e.g., manufacturing variations/tolerances, changing environmental conditions, inlet temperature, inlet temperature distribution, flow rate, velocity distribution, fluid composition, individually controlled to a desired temperature or desired power level to adapt to changes in inlet flow conditions such as fluid heat capacity, etc.). More specifically, the heater units 52 may not generate the same heat output when operated at the same power level due to manufacturing variations and variations in the degree of heater deterioration over time. The heater units 52 may be independently controlled to adjust the heat output according to a desired heat distribution. The individual manufacturing tolerances of the heater system components and the heater system assembly tolerances increase according to the regulated power of the power supply, in other words, because the accuracy of heater control is high, the manufacturing tolerances of individual components may be tight or narrow. No need.

Each of the heater units 52 may include a temperature sensor (not shown) for measuring the temperature of the heater units 52 . When a hot spot is detected in the heater units 52 , the power supply device 14 controls the specific heater unit 52 where the hot spot is detected in order to avoid overheating or failure of the specific heater unit 52 . ) to reduce or cut off the power supplied to The global supply 14 may regulate the power supplied to the heater units 52 adjacent the deactivated heater unit 52 to compensate for the reduced heat output from the particular heater unit 52 .

The power supply 14 is configured to block or reduce the level of power delivered to any specific zone, and to increase power to heating zones adjacent to the specific heating zone that is deactivated and has reduced heat output; It may include multi-zone algorithms. By carefully adjusting the power to each heating zone, the overall reliability of the system can be improved. By detecting hot spots and controlling the power supply accordingly, the heater system 10 has improved safety.

A heater bundle 12 having multiple independently controlled heating zones 62 can achieve improved heating. For example, some circuits in the heater unit 52 may have a nominal (or “typical”) duty cycle of less than 100% (or line voltage being a fraction of the power to be generated by the applied heater). at an average power level). Lower duty cycles allow the use of larger diameter resistive heating wires, thereby improving reliability.

In general, smaller regions will employ finer wire sizes to achieve a given resistance. Variable power control allows larger wire sizes to be used and lower resistance values can be accommodated while protecting the heater from overload by a duty cycle limit related to the power dissipation capacity of the heater.

The use of a scaling factor may be related to the capacity of the heater units 52 or heating zone 62 . Multiple heating zones 62 allow more accurate determination and control of heater bundle 12 . The use of a specific coefficient factor for a particular heating circuit/zone will allow for a more aggressive (ie, higher) temperature (or power level) in almost all zones, which in turn will result in a smaller and more Leads to cheap design. Such counting factors and methods are disclosed in US Pat. No. 7,257,464, which is incorporated herein by reference, the contents of which are incorporated herein by reference in their entirety.

The sizes of the heating zones controlled by the individual circuits can be made the same or different to reduce the total number of zones needed to control the distribution of temperature or power with a desired accuracy.

Referring again to FIG. 1 , the heater assemblies 18 are shown as a single ended heater, ie, the conductive fin extends through only one longitudinal end of the heater assemblies 18 . The heater assembly 18 may extend through a mounting flange 16 or bulkhead (not shown) and is sealed to the flange 16 or bulkhead. As such, the heater assemblies 18 can be individually removed and replaced without removing the mounting flange 16 from the vessel or tube.

Alternatively, the heater assembly 18 may be a “double ended” heater. In a double-ended heater, the metal sheath is bent into a hairpin shape so that both longitudinal ends of the metal sheath pass through the flange or partition wall and are sealed to the flange or partition wall, and the power conductors pass through both longitudinal ends of the metal sheath. In this construction, the flange or septum needs to be removed from the housing or vessel before the individual heater assemblies 18 can be replaced.

Referring to FIG. 6 , the heater bundle 12 is integrated into the heat exchanger 70 . The heat exchanger 70 includes a sealed housing 72 defining an inner chamber (not shown), and a heater bundle 12 disposed within the inner chamber of the housing 72 . The sealed housing 72 includes a fluid inlet 76 and a fluid outlet 78 through which fluid is guided into and out of the inner chamber of the sealed housing 72 . The fluid is heated by a heater bundle 12 disposed within a sealed housing 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 14, which may include means for regulating power, such as switching means or a variable transformer, to regulate the power supplied to the individual zones. Power regulation may be performed as a function of time or based on the detected temperature of each heating zone.

The resistive heating wire can also function as a sensor that uses the resistance of the resistive wire to measure the temperature of the resistive wire and uses the same power conductors to transmit the temperature measurement information to the power supply 14 . The temperature sensing means for each zone will allow control of the temperature (up to the resolution of the individual zone) along the length of each heater assembly 18 in the heater bundle 12 . Accordingly, additional temperature sensing circuits and sensing means can be omitted, thereby reducing manufacturing cost. Direct measurement of heater circuit temperature is a clear advantage when trying to maximize heat flux within a given circuit while maintaining the desired level of reliability for 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 heater reliability. The use of resistive elements to function as both a heater and a sensor is disclosed in US Pat. No. 7,196,295, which is incorporated herein by reference, the contents of which are incorporated herein by reference in their entirety.

Alternatively, the power conductors 56 of dissimilar metals may be made of dissimilar metals such that the power conductors 56 can create a thermocouple for measuring the temperature of the resistive heating elements. have. For example, the at least one set of power supply and power return conductors may include different materials such that a junction is formed between the different materials and the resistive heating element of the heater unit and the junction determines the temperature of the one or more zones. can be used to do so. The use of “integrated” and “very thermally coupled” sensing, eg the use of different metals for a heater, leads to the generation of a thermocouple-like signal. The use of integrated and coupled power conductors for temperature measurement is disclosed in US Application Serial No. 14/725,537, which is jointly incorporated herein by reference, the contents of which are incorporated herein by reference in their entirety. .

The controller 15 for regulating the power delivered to each zone may be a closed-loop automatic control system. The closed-loop automatic control system receives temperature feedback from each zone and automatically and dynamically controls the power supply to each zone, thereby providing each in the heater bundle 12 without continuous or frequent human monitoring and adjustment. Automatically and dynamically control power distribution and temperature along the length of the heater assembly 18 of

The heater units 52 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 the calibrated resistance to determine a resistance ratio, or compared to a value to determine the actual heater unit temperature. Exemplary methods are disclosed in US Pat. Nos. 5,280,422 and 5,552,998, which are incorporated herein by reference, the contents of which are incorporated herein by reference in their entirety.

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

In variations of the present disclosure, the heater system may include a single heater assembly 18 , rather than a plurality of heater assemblies in a heater bundle 12 . A single heater assembly 18 will include a plurality of heater units 52 , each heater unit 52 defining at least one independently controlled heating zone. Similarly, power conductors 56 are electrically connected to each of the independently controlled heating zones 62 within each heater unit 52 , and a power supply is provided via the power conductors 56 to each of the heater units. configured to regulate power to each of the independently controlled heating zones 62 .

Referring to FIG. 7 , a method 100 of controlling a heater system includes, at step 102 , providing a heater bundle comprising a plurality of heater assemblies. Each heater assembly includes a plurality of heater units. Each heater unit defines at least one independently controlled heating circuit (and consequently a heating zone). In step 104 , power to each of the heater units is supplied via power conductors electrically connected to each of the independently controlled heating zones of each of the heater units. In step 106, the temperature inside each of the zones is detected. The temperature may be determined using a change in resistance of the resistive heating element of at least one of the heater units. The zone temperature can be initially determined by measuring the zone resistance (or by measuring the circuit voltage, if suitable materials are used).

The temperature values can be digitized. Signals may be passed to a microprocessor. In step 108 , the measured (detected) temperature values may be compared to a target (desired) temperature for each zone. In step 110 , in order to achieve target temperatures, the power supplied to each of the heater units may be adjusted based on the measured temperature.

Optionally, the method may further comprise using a scaling factor to adjust the modulation power. The coefficient factor may be a function of the heating capacity of each heating zone. The controller 15 controls (updating the system) to determine the amount of power to be provided to each zone (via duty cycle, phase angle firing, voltage modulation or similar techniques) until the next update. Algorithms potentially including mathematical models and/or coefficient factors of the dynamic behavior of the system (including knowledge of time). The desired power can be converted into a signal, which is sent to a switch or other power conditioning device to control the power output to the individual heating zones.

In this aspect, when at least one heating zone is turned off due to an abnormal condition, the remaining zones continue to provide the desired amount of power without failure. Power is regulated for the activated heating zone to provide a desired amount of power when an abnormal condition is detected in the at least one heating zone. When one or more heating zones are turned off according to the determined temperature, the remaining zones continue to provide the desired amount of power. Power is adjusted for each of the heating zones as a function of at least one of the received signals, the model, and as a function of time.

For safety or process control reasons, typical heaters are generally required to prevent a specific location of the heater from exceeding a given temperature due to undesired chemical or physical reactions (eg, combustion/ignition/oxidation, coke boiling, etc.) at that specific location. to operate below the maximum permissible temperature. Thus, this is generally accommodated by conservative heater designs (eg, large heaters with low power densities and with most of the surface area loaded at a much lower heat flux than is possible).

However, with the heater bundle of the present disclosure, it is possible to measure and limit the temperature at any location inside the heater to a resolution for the size of the individual heating zones. Hot spots large enough to affect the temperature of the individual circuit can be detected.

Because the temperature of the individual heating zones can be automatically adjusted and consequently limited, the dynamic and automatic limiting of the temperature within each zone ensures that this zone and all other zones are optimally controlled without the risk of exceeding the desired temperature limit in any zone. It will keep operating at the power/heat flux level. This provides an advantage in limiting temperature measurement accuracy over the current practice of clamping a separate thermocouple to the sheath of one of the elements in the bundle. The reduced margin and ability to regulate power to individual zones can be selectively applied to heating zones, individually, rather than to the entire heater assembly, thereby reducing the risk of exceeding a predetermined temperature limit. Reduce.

The characteristics of a cartridge heater can change over time. This time-varying nature would otherwise require the cartridge heater to be designed for a single selected (worse case) flow regime, so that the cartridge heater would not be suboptimal for other flow conditions. sub-optimum) will work.

However, by dynamic control of the power distribution for the entire bundle up to a core-sized resolution due to the multiple heating units provided in the heater assembly, optimized power distribution for various flow conditions can be achieved, which is typical of a cartridge In contrast to only one power distribution corresponding to only one flow state in the 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 can increase the flexibility of heater design. Voltage can be decoupled (to a significant extent) from the resistance in the heater design, and the heaters can be designed to have the largest wire diameter that can be mounted to the heater. This allows for increased power dissipation capacity for a given heater size and reliability level (or heater life), and allows the size of the bundle to be reduced for a given overall power level. In this configuration, power may be regulated by variable duty cycle, which is part of variable wattage controllers currently available or in development. The heater bundle may be protected by a programmable (or pre-programmed, if desired) limit on the duty cycle for a given zone to prevent "overload" of the heater bundle.

Referring now to FIGS. 8A - 8D , at least one heater assembly 50 as described above is configured to deliver a variable power output per unit length along the length of the at least one heater assembly 50 . Additional forms of the present disclosure having a physical configuration are shown. This variable power output may be implemented in various ways and in various combinations, some of which are shown and described herein as examples. The physical configurations described below may be provided within one or more heater units 52 , and within one or more heater assemblies 50 in any combination. Further, the additional teachings herein of variable power output may be combined with any of the previously described forms of the present disclosure, either individually or in any combination, while remaining within the scope of the present disclosure.

In one form illustrated in FIG. 8A , the variable power output is provided by the physical configuration of the resistive heating element 120 having a variable pitch. As used herein, the term “pitch” refers to the central point of successive windings of resistive heating element 120 along longitudinal direction X, as indicated in this example by P1 , P2 and P3 . refers to the spacing between As shown in this example, the heater unit 52 has three distinct zones with different pitches P1 , P2 , P3 .

In another configuration shown in FIG. 8B , the pitch is continuously varied along the length of the resistive heating element 120 , or along the longitudinal direction X. More specifically, the pitch between each of the windings varies continuously along the length, or in other words, the pitch between adjacent windings is continuously different from one winding to the next. In this example, P1 ≠ P2 ≠ P3 ≠ P4 ≠ P5 ≠ P6 ≠ P7 ≠ P8. However, if the pitches between adjacent windings are different for a continuous variable pitch from one winding to the next, a pitch equal to P4 may be equal to a pitch P7.

In another form shown in FIG. 8C , the variable power output is provided by a resistive heating element 120 having a variable cross-sectional area. This variable cross-sectional area is provided by a resistive heating element 120 having different wire diameters D1, D2, D3 as shown, or a resistive heating element in which the wire diameter itself can be continuously varied along its length ( not shown) may be provided. In another example, not shown, when resistive heating element 120 is formed by a lamination process, its thickness and/or width may vary for variable power output. This configuration is described in greater detail in U.S. Patent No. 7,132,628 entitled "Variable Power Density Laminar Heater System," which is jointly owned with this application, the contents of which are incorporated herein by reference in their entirety. . It should be understood that these and other variations that provide a variable cross-sectional area to the resistive heating element 120 should be construed as falling within the scope of the present disclosure.

Referring to a further example of FIG. 8D , a variable power output may be provided by a resistive heating element 120 having both a variable cross-sectional area and a variable pitch. In this example, three different cross-sectional areas are denoted by diameters D1 , D2 and D3 , and three different pitches are denoted by pitches P1 , P2 and P3 . These examples and other combinations of different cross-sectional areas and pitches for providing variable power output within each heater unit 52 should be construed as being within the scope of the present disclosure.

Referring now to FIG. 8E , at least one of the heater units 52 , in another form, has different resistance values R1 , R2 , R1 , R2 , for each resistive heating element 120 to provide a variable power output. a plurality of parallel circuits having R3, R4, and R5). In this configuration, each resistive heating element 120 is electrically connected across power conductors 42 in parallel. In another form, bus bars (not shown) may be used to connect the resistive heating elements 120 in parallel, which bus bars are then in electrical communication with the power conductors 42 . . It should be understood that any number of resistive heating elements 120 and different resistance values may be employed other than those shown herein while remaining within the scope of the present disclosure. For different resistance values, this can be achieved in a variety of ways, including, for example, different material compositions and different cross-sectional areas, among others.

In one form of the present disclosure, each heater unit 52 has a different power distribution than adjacent heater units in a given heater assembly 50 . In another aspect, at least one heater unit 52 has independently controlled heating zones with variable power output in more than one heater assembly 50 . It should be understood that, among other variations shown herein for variable power output, these may be employed with heater bundles and heater assemblies and shown and described herein while remaining within the scope of the present disclosure.

In yet another form, variable power output may be achieved by using a composite heating element. The composite heating element is made of a material comprising a material having a variable electrical resistivity along its length and is thus configured to deliver a variable power output. For example, a composite heating element of a heater unit has a higher electrical resistivity at one end (near an adjacent heater unit or near the end of a heater assembly) and a lower electrical resistivity at the other end (near another adjacent heater unit on the opposite side). have

Referring to FIG. 9 , in another variation of the present disclosure, the physical configuration includes at least one heater unit 52 having a cross-sectional area different from adjacent heater units. It should be understood that more than one heater unit 52 may have a different cross-sectional area than others, and that one or more heater assemblies 50 may have heater units 52 having different cross-sectional areas. Combined with the modulation of power to the independently controlled heating zones as presented above, these variable cross-sectional areas (in addition to the other physical configurations described herein) can be derived from the power values per unit area of independently controlled zones. Another way to create a greater difference in power output along the length of the heater assemblies 50 while decoupling the physical components that provide a variable power output.

Unless expressly indicated otherwise herein, all numerical values representing mechanical/thermal properties, composition percentages, dimensions and/or tolerances, or other properties are referred to as “about” or “approximately” when describing the scope of the present disclosure. It should be understood as being modified by the word " Such modifications are desirable for a variety of reasons including industry practice, materials, manufacturing, and assembly tolerances, and testing capabilities. .

Spatial and functional relationships between elements include "connected", "interlocked", "coupled", "adjacent", "next to", "above", "above", "below", and "disposed". described using a variety of terms, including Unless explicitly stated as “direct,” when a relationship between first and second elements is described in the present disclosure, the relationship is a direct relationship between the first and second elements in which no other intermediate elements exist. relationship, and may also be an indirect relationship in which one or more intermediate elements exist (spatially or functionally) between the first element and the second element. As used herein, the phrase at least one of A, B, and C is to be construed to mean logical (A OR B OR C), using a non-exclusive logical OR, "at least one of A, B of at least one, and at least one of C."

The description of the present disclosure is merely exemplary in nature, and thus, modifications that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such modifications should not be considered as a departure from the spirit and scope of the present disclosure.

Claims (22)

A heater system comprising a heater bundle, means for determining a temperature, and a power supply, comprising:
The heater bundle includes:
A plurality of heater assemblies, wherein at least one of the heater assemblies comprises a plurality of heater units, the at least one heater unit having an independently controlled heating zone, the at least one heater assembly comprising the at least one heater assembly a plurality of heater assemblies comprising a physical construction configured to deliver a variable power output per unit length along a length of ; and
a plurality of power conductors electrically connected to the plurality of heater units; and
The power supply includes a controller configured to regulate power to the independently controlled heating zone via the power conductors based on a temperature determined to provide a desired power output along a length of the at least one heater assembly. which, heater system. According to claim 1,
wherein the physical configuration includes a resistive heating element having a variable pitch within at least one heater unit. 3. The method of claim 2,
and the variable pitch is continuously variable along the length of the resistive heating element. According to claim 1,
wherein the physical configuration includes a resistive heating element having a variable cross-sectional area within at least one heater unit. According to claim 1,
wherein the physical configuration includes a resistive heating element having a variable cross-sectional area and a variable pitch within the at least one heater unit. According to claim 1,
wherein the physical configuration includes a plurality of parallel circuits within at least one heater unit. According to claim 1,
and the physical configuration is provided for more than one of the plurality of heater units. According to claim 1,
wherein the physical configuration includes an adjacent heater unit or composite heating element having a higher electrical resistivity proximate to an end of the at least one heater assembly and a lower electrical resistivity proximate to an opposing other adjacent heater unit. . According to claim 1,
and the physical configuration is provided for more than one of the heater assemblies. According to claim 1,
at least one heater assembly of the plurality of heater assemblies is a cartridge heater. According to claim 1,
wherein the physical configuration includes at least one heater unit having a different cross-sectional area than adjacent heater units. According to claim 1,
wherein the heater units include a plurality of resistive heating elements, at least one of the resistive heating elements functioning as a sensor. According to claim 1,
wherein the physical configuration includes a composite heating element having a variable electrical resistivity. 14. The method of claim 13,
wherein the variable electrical resistivity includes a higher electrical resistivity proximate to an end of an adjacent heater unit or at least one heater assembly and a lower electrical resistivity proximate an opposite adjacent heater unit. As a fluid heating device:
a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet; and
The heater system according to claim 1;
the heater bundle is disposed inside the inner chamber of the housing;
wherein the heater bundle is configured to provide a responsive heat distribution to the fluid within the housing. A heater system comprising a heater bundle, means for determining at least one of heating conditions and heating requirements, and a power supply;
The heater bundle includes:
A plurality of heater assemblies, wherein at least one of the heater assemblies comprises a plurality of heater units, the at least one heater unit having an independently controlled heating zone, the at least one heater assembly comprising the at least one heater assembly a plurality of heater assemblies comprising a physical construction configured to deliver a variable power output per unit length along a length of ; and
a plurality of power conductors electrically connected to the plurality of heater units; and
The power supply is configured to provide a power output to the independently controlled heating zone via the power 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. A heater system comprising a controller configured to regulate power. 17. The method of claim 16,
At least one of heating conditions and heating requirements is determined by the lifetime of the heater units, the reliability of the heater units, the size of the heater units, the cost of the heater units, heater flux, characteristics of the heater units, and A heater system selected from the group consisting of actuation, power output, power input, and total power output. As a fluid heating device:
a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet; and
The heater system according to claim 16;
the heater assembly is disposed inside the inner chamber of the housing;
wherein the heater assembly is configured to provide a responsive heat distribution to the fluid within the housing. A heater assembly comprising a plurality of heater units, wherein at least one heater unit has an independently controlled heating zone, the heater assembly having a physical configuration configured to deliver a variable power output per unit length along a length of the heater assembly; a heater assembly, including physical construction;
a plurality of power conductors electrically connected to the heater units; and
a controller configured to regulate power to the independently controlled heating zone via the power conductors based on at least one of heating conditions and heating requirements to provide a desired power output along the length of the heater assembly. A heater system comprising a power supply. 20. The method of claim 19,
and means for determining the temperature. 20. The method of claim 19,
and means for determining heating conditions or heating requirements. As a fluid heating device:
a sealed housing defining an inner chamber and having a fluid inlet and a fluid outlet; and
The heater system according to claim 19;
the heater assembly is disposed inside the inner chamber of the housing;
wherein the heater assembly is configured to provide a responsive heat distribution to the fluid within the housing.

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