JP2022140401A - Heater bundles having variable power output within zones - Google Patents

Abstract

To provide a heater system including a heater bundle.SOLUTION: A heater system includes a heater bundle with heater assemblies, at least one of the heater assemblies having a plurality of heater units, at least one heater unit having an independently controlled heating zone, and the at least one heater assembly having 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 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 the determined temperature to provide a desired power output along a length of the at least one heater assembly.SELECTED DRAWING: Figure 1

Description

Cross-reference to related applications
This application is a continuation of U.S. patent application Ser. is a continuation-in-part of U.S. Patent No. 16/272,668 entitled "Heater Bundle for Adaptive Control". The contents of the above disclosure are incorporated herein by reference in their entirety.

FIELD OF THE DISCLOSURE The present disclosure relates to electrical heaters, and more particularly to heaters for heating fluid streams, such as heat exchangers.

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 configuration for heating fluid flowing along or past the outer surface of the cartridge heater. A cartridge heater may be disposed inside the heat exchanger for heating fluid flowing through the heat exchanger. If the cartridge heater is not properly sealed, moisture and fluids can enter the cartridge heater to 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 failure of the heater. Moisture can also cause shorts between the power conductors and the outer metal sheath. Cartridge heater failure can cause costly downtime for equipment using the cartridge heater.

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

In variations of this heating system, which may be implemented individually or in any combination, the physical structure comprises resistive heating elements within at least one heating unit having a variable pitch, the variable pitch being the continuously variable along the length, the physical structure comprising at least one resistive heating element in the heating unit having a variable cross-sectional area, the physical structure having at least one variable cross-sectional area and a variable pitch; the physical structure comprises a plurality of parallel circuits in at least one heating unit; the physical structure is provided in two or more of the plurality of heating units; A composite heating structure has a higher electrical resistivity proximate an edge of an adjacent heating unit or at least one heating assembly and a lower electrical resistivity proximate another opposing adjacent heating unit. wherein the physical structure is provided in two or more of the heating assemblies, at least one heating assembly of the plurality of heating assemblies is a cartridge heater, and the physical structure is adjacent heating units at least one heating unit having a cross-sectional area different from the heating unit, the heating unit comprising a plurality of resistive heating elements, at least one of the resistive heating elements acting as a sensor, the physical structure comprising a variable electrical resistivity wherein the variable electrical resistivity comprises a higher electrical resistivity proximate an edge of the adjacent heating unit or at least one heating assembly and a lower electrical resistance proximate the opposing adjacent heating unit Including rate and.

In another form, an apparatus for heating a fluid comprises the aforementioned heating system with a sealed housing defining an interior chamber and having a fluid inlet and a fluid outlet, wherein the heating bundle is disposed within the interior chamber of the housing. be done. The heating bundle is adapted to provide responsive heat distribution to the fluid within the housing.

In yet another form, a heating system includes a heating bundle including a plurality of heating assemblies, at least one of the heating assemblies including a plurality of heating units, at least one heating unit being independently controlled. The at least one heating assembly includes a physical structure configured to deliver a variable power output per unit length along the length of the at least one heating assembly. A plurality of power conductors are electrically connected to the heating unit and means are provided for determining at least one of a heating condition and a heating requirement. The power supply modulates power to the independently controlled heating regions via the power conductors based on at least one of the heating conditions and heating requirements to provide desired heating along the length of the at least one heating assembly. a controller configured to provide a power output of the

In this variation of the heating system, at least one of the heating conditions and heating requirements is heating unit life, heating unit reliability, heating unit size, heating unit cost, heater flux, heating unit Selected from the group consisting of properties and operations, power output, power input, and total heat generated.

In a further variation, the device includes a sealed housing defining an internal chamber and having a fluid inlet and a fluid outlet. A heating assembly is disposed within the interior chamber of the housing, the heating assembly adapted to provide a heat distribution responsive to fluid within the housing.

In yet another aspect of the present disclosure, a heating system comprises a heating assembly comprising a plurality of heating units, at least one heating unit having an independently controlled heating area, the heating assembly comprising: It comprises a physical structure configured along its length to deliver a variable power output per unit length. A plurality of power conductors are electrically connected to the heating unit, the power supply configured to provide a desired power output along the length of the heating assembly based on at least one of the heating conditions and heating requirements. , including a controller configured to modulate power to the independently controlled heating regions via the power conductors.

Variations of this heating system, which may be implemented individually or in any combination, provide means for determining temperature and provide means for determining heating conditions or requirements.

In another form of this heating system, an apparatus for heating a fluid comprises a sealed housing defining an interior chamber and having a fluid inlet and a fluid outlet, a heating assembly disposed within the interior chamber of the housing. be. The heating assembly is adapted to provide responsive heat distribution 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 for purposes of illustration only and are not intended to limit the scope of the present disclosure.

In order that the disclosure may be fully understood, various forms thereof, given by way of example, will now be described with reference to the accompanying drawings.

1 is a perspective view of a heating bundle constructed in accordance with the teachings of the present disclosure; FIG. 2 is a perspective view of a heating assembly of the heating bundle of FIG. 1 in accordance with the teachings of the present disclosure; FIG. 2 is a perspective view of a variation of the heating assembly of the heating bundle of FIG. 1 in accordance with the teachings of the present disclosure; FIG. 4 is a perspective view of the heating assembly of FIG. 3 with the outer sheath of the heating assembly removed for clarity in accordance with the teachings of the present disclosure; FIG. 4 is a perspective view of the core of the heating assembly of FIG. 3 in accordance with the teachings of the present disclosure; FIG. 2 is a perspective view of a heat exchanger including the heating bundle of FIG. 1 in accordance with the teachings of the present disclosure, partially disassembled therefrom to expose the heating bundle for illustrative purposes; FIG. 1 is a block diagram of a method of operating a heating system including a heating bundle constructed in accordance with the teachings of the present disclosure; FIG. 1 is a side view of one form of heating unit having a variable power output constructed in accordance with the teachings of the present disclosure; FIG. FIG. 4 is a side view of another form of heating unit having a variable power output constructed in accordance with the teachings of the present disclosure; FIG. 4 is a side view of yet another form of heating unit having a variable power output constructed in accordance with the teachings of the present disclosure; FIG. 4 is a side view of yet another form of heating unit having a variable power output constructed in accordance with the teachings of the present disclosure; FIG. 4 is a schematic side view of another form of heating unit having multiple parallel circuits for providing variable power output in accordance with the teachings of the present disclosure; 2A-2D are perspective views of heating units having different cross-sectional areas and constructed in accordance with the teachings of the present disclosure;

The drawings described herein are for illustration purposes only and are in no way intended to limit the scope of the disclosure.

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

Referring to FIG. 1, a heating system constructed in accordance with the teachings of the present disclosure is indicated generally at 10. As shown in FIG. Heating system 10 includes a heating bundle 12 and a power supply 14 electrically connected to heating bundle 12 . Power supply 14 includes a controller 15 for controlling the power supply to heating bundle 12 . A "heating bundle" as used in this disclosure refers to a heating device that includes two or more physically separate heating devices that can be independently controlled. Thus, if one of the heating devices within the heating bundle fails or deteriorates, the remaining heating devices within the heating bundle 12 can continue to operate.

In one form, heating bundle 12 includes a mounting flange 16 and a plurality of heating assemblies 18 secured to mounting flange 16 . Mounting flange 16 includes a plurality of openings 20 through which heating assemblies 18 extend. Although the heating assemblies 18 are arranged in parallel in this configuration, it should be understood that alternate positions/arrangements of the heating assemblies 18 are within the scope of this disclosure.

As further shown, 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 heating assembly 18 is immersed in the fluid inside the container or tube to heat the fluid in this form of the disclosure.

Referring to FIG. 2, heating assembly 18 according to one form may be in the form of a cartridge heater 30 . Cartridge heater 30 generally includes a core 32 , resistive heating wiring 34 wrapped around core 32 , a metal sheath 36 internally enclosing core 32 and resistive heating wiring 34 , and and an insulating material 38 which is filled in the space of the resistance heating wiring 34 and electrically insulates the resistance heating wiring 34 from the metal sheath 36 and conducts heat from the resistance heating wiring 34 to the metal sheath 36 . The core 32 may be made of ceramic. Insulating material 38 may be compressed magnesium oxide (MgO). A plurality of power conductors 42 penetrate the core 32 along the longitudinal direction and are electrically connected to the resistance heating wiring 34 . A power conductor 42 also extends through an end piece 44 that seals the metal sheath 36 . The power conductor 42 is connected to the power supply 14 (shown in FIG. 1) and supplies power from the power supply 14 to the resistive heating wiring 34 . Although FIG. 2 shows only two power conductors 42 extending through end piece 44 , more than two power conductors 42 may extend through end piece 44 . Power conductors 42 may be in the form of conductive pins. Various constructions and further structural and electrical details of cartridge heaters are described in U.S. Pat. , 970,822. Accordingly, it should be understood that the forms set forth herein are exemplary only and should not be construed as limiting the scope of the present disclosure.

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

3-5, heating assembly 50 may be in the form of a cartridge heater having a configuration similar to that of FIG. 2, except for the number of cores and power conductors used. More specifically, the heating assemblies 50 each include a plurality of heating units 52 and an outer metal sheath 54 enclosing the plurality of heating units 52 therein, along with a plurality of power conductors 56 . An insulating material (not shown in FIGS. 3-5) is provided between the plurality of heating units 52 and the outer metal sheath 54 to electrically insulate the heating units 52 and the outer metal sheath 54. there is The plurality of heating units 52 each include a core 58 and a resistive heating element 60 surrounding the core 58 . The resistive heating elements 60 of each heating unit 52 may define one or more heating circuits for defining one or more heating zones 62 .

In this embodiment, each heating unit 52 defines one heating region 62 and the plurality of heating units 52 within each heating assembly 50 are aligned along the longitudinal direction X. As shown in FIG. Each heating assembly 50 thus defines a plurality of heating zones 62 aligned along the longitudinal direction X. As shown in FIG. Core 58 of each heating unit 52 defines a plurality of through holes/openings 64 to allow power conductors 56 to pass therethrough. Resistive heating element 60 of heating unit 52 is connected to power conductor 56 , which is connected to power supply 14 . Power conductors 56 provide power from power supply 14 to multiple heating units 52 . By appropriately connecting the power conductors 56 to the resistive heating elements 60 , the resistive heating elements 60 of the plurality of heating units 52 can be independently controlled by the controller 15 of the power supply 14 . Thus, failure of one resistive heating element 60 for a particular heating zone 62 does not affect the proper functioning of the remaining resistive heating elements 60 for the remaining heating zones 62 . Further, heating unit 52 and heating assembly 50 may be replaceable for ease of repair or assembly.

In this embodiment, six power conductors 56 are used for each heating assembly 50 to power five independent electrical heating circuits on five heating units 52 . Alternatively, six power conductors 56 may be connected to resistive heating elements 60 to define three completely independent circuits on five heating units 52 . It is possible to have any number of power conductors 56 to form any number of independently controlled heating circuits and independently controlled heating regions 62 . For example, seven power conductors 56 can be used to provide six heating regions 62 . Eight power conductors 56 may be used to provide seven heating zones 62 .

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

Alternatively, creating a greater number of electrically distinct heating regions 62 by multiplexing, polarity sensitive switching, and other circuit topologies by the controller 15 of the power supply 14. can be done. Multiplexing or varying the thermal array to increase the number of heating zones within the cartridge heater 30 for a given number of power conductors (e.g., a cartridge heater with 6 power conductors for 15 or 30 zones). The use of placement is disclosed in U.S. Pat. Nos. 9,123,755, 9,123,756, 9,177,840, 9,196,513 and their related applications, These are commonly assigned with this application, the contents of which are hereby incorporated by reference in their entireties.

With this construction, each heating assembly 50 includes multiple heating zones 62 that can be independently controlled to vary the power output or heat distribution along the length of the heating assembly 50 . Heating bundle 12 includes a plurality of such heating assemblies 50 . Heating bundle 12 thus provides a plurality of heating zones 62 and a tailored heat distribution for heating the fluid flowing through heating bundle 12 to suit a particular application. Power supply 14 may be configured to modulate power to each of the independently controlled heating regions 62 .

For example, the heating assemblies 50 may define “m” heating zones and a heating bundle may include “k” heating assemblies 50 . Thus, the heating bundle 12 can define m×k heating zones. The plurality of heating zones 62 within the heating bundle 12 is determined by the life and reliability of the individual heating units 52, the size and cost of the heating units 52, the flux of the heaters, the characteristics and operation of the heating units 52, the power output. , power input, and heating conditions and/or requirements including, but not limited to, total heat generated.

Each circuit, or selected heating area, may vary in temperature and/or power distribution depending on system parameters (e.g., manufacturing variations/tolerances, changes in environmental conditions, inlet temperature, inlet temperature distribution, flow velocity, velocity distribution, fluid composition, It is individually controlled at the desired temperature or desired power level to adapt to variations in inlet flow conditions such as fluid heat capacity. More specifically, the heating units 52 may not produce the same heat output when operated at the same power level due to manufacturing variations as well as varying degrees of thermal degradation over time. Heating units 52 may be independently controlled to adjust the heat output according to the desired heat distribution. The individual manufacturing tolerances of the components of the heating system and the assembly tolerances of the heating system are increased as a function of the modulated power of the power supply, in other words due to the high fidelity of the heating control, the manufacturing tolerances of the individual components are , need not be so tight/narrow.

Heating units 52 may each include a temperature sensor (not shown) for measuring the temperature of heating unit 52 . If a hot spot within heating unit 52 is detected, power supply 14 may reduce or reduce power to the particular heating unit 52 in which the hot spot is detected to avoid overheating or failure of the particular heating unit 52 . can be turned off. Power supply 14 may modulate power to heating units 52 adjacent to a disabled heating unit 52 to compensate for the reduced heat output from a particular heating unit 52 .

The power supply 14 has multiple power supplies for turning off or reducing the power level supplied to any particular area and increasing power to the heating areas adjacent to the particular heating area that has been disabled to reduce heat output. Region algorithms can be included. By carefully modulating the power to each heating region, the overall reliability of the system can be improved. By detecting hot spots and controlling the power supply accordingly, the safety of the heating system 10 is improved.

A heating bundle 12 having multiple independently controlled heating zones 62 can achieve improved heating. For example, some circuits on the heating unit 52 have a nominal (or "typical") duty cycle of less than 100% (or an average power level). A lower duty cycle allows the use of resistive heating wiring with a larger diameter, thereby improving reliability.

Smaller areas typically use finer wire sizes to achieve a given resistance. Variable power control allows the use of larger wire sizes and can accommodate lower resistance values while keeping the heater from overloading due to duty cycle limits tied to the power dissipation capability of the heater. can be protected.

The use of scaling factors may relate to the capacity of heating unit 52 or heating area 62 . Multiple heating zones 62 allow for more precise determination and control of heating bundle 12 . The use of specific scaling factors for specific heating circuits/areas allows for more aggressive (i.e. higher) temperatures (or power levels) in nearly all areas, which in turn allows for a smaller heating bundle 12. results in a low cost design. Such scaling factors and methods are disclosed in US Pat. No. 7,257,464, commonly assigned with this application and incorporated herein by reference in its entirety.

The sizes of the heating areas controlled by the individual circuits may be equal or different to reduce the total number of areas required to control the temperature or power distribution to the desired precision.

Referring back to FIG. 1, heating assembly 18 is shown to be a single-ended heater, ie, conductive pins extend through only one longitudinal end of heating assembly 18 . The heating assembly 18 may extend through a mounting flange 16 or septum (not shown) and be sealed to the flange 16 or septum. Thus, the heating assemblies 18 can be individually removed and replaced without removing the mounting flange 16 from the container or tube.

Alternatively, heating assembly 18 may be a "double-ended" heater. In double-ended heating, the metal sheath is bent into a hairpin shape and the power conductors pass through both longitudinal ends of the metal sheath so that the longitudinal ends of the metal sheath pass through flanges or partitions and are sealed. This construction requires that the flange or septum be removed from the housing or container before an individual heating assembly 18 can be replaced.

Referring to FIG. 6, heating bundle 12 is incorporated into heat exchanger 70 . Heat exchanger 70 includes a sealed housing 72 defining an interior chamber (not shown) and heating bundle 12 disposed within the interior chamber of housing 72 . The sealed housing 72 includes a fluid inlet 76 and a fluid outlet 78 through which fluid is directed into and out of the interior chamber of the sealed housing 72 . The fluid is heated by heating bundles 12 located within a sealed housing 72 . Heating bundles 12 may be arranged for either cross-flow or parallel-to-the-length flow.

The heating bundles 12 are connected to a power supply 14 which may include means for modulating power, such as switching means or variable transformers, to modulate the power supplied to the individual regions. Power modulation 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, using the resistance of the resistive wire to measure the temperature of the resistive wire and transmitting the temperature measurement information to the power supply 14 using the same power conductor. The means for sensing the temperature of each zone allows temperature control (to the resolution of individual zones) along the length of each heating assembly 18 within the heating bundle 12 . Therefore, additional temperature sensing circuitry and sensing means can be omitted, thereby reducing manufacturing costs. Direct measurement of heating circuit temperature eliminates or minimizes many of the measurement errors associated with the use of separate sensors, thus maximizing heat flux within a given circuit while maintaining the desired level of system reliability A definite advantage when trying to Heating element temperature is the characteristic that has the strongest effect on heating reliability. The use of resistive elements to function as both heaters and sensors is disclosed in U.S. Pat. No. 7,196,295, commonly assigned with this application and incorporated herein by reference in its entirety. It is

Alternatively, the power conductor 56 may be made of a dissimilar metal such that the dissimilar metal power conductor 56 can form a thermocouple for measuring the temperature of the resistive heating element. For example, at least one set of power supply and power return conductors may be used to determine the temperature of one or more regions, where junctions are formed between different materials and resistive heating elements of the heating unit. can contain different materials. The use of "integrated" and "highly thermally coupled" sensing, such as using different metals in the heater, produces a thermocouple-like signal. The use of integrated and coupled power conductors for temperature measurement is disclosed in U.S. Pat. No. 10,728,956, commonly assigned with this application and incorporated herein by reference in its entirety. there is

The controller 15 for modulating the power supplied 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 the delivery of electrical power to each zone, thereby operating the heating bundle 12 without continuous or frequent human monitoring and adjustment. automatically and dynamically control the power distribution and temperature along the length of each heating assembly 18 within.

The heating units 52 disclosed herein may also be calibrated using a variety of methods including, but not limited to, energizing and sampling each heating unit 52 to calculate its resistance. The calculated resistance can then be compared to the calibrated resistance to determine a resistance ratio or a value that determines the actual heating unit temperature. Exemplary methods are disclosed in US Pat. Nos. 5,280,422 and 5,552,998, commonly assigned with this application and incorporated herein by reference in their entireties.

One form of calibration is operating the heating system 10 in at least one mode of operation and controlling the heating system 10 to produce a desired temperature for at least one of the independently controlled heating zones 62 . collecting and recording data for at least one independently controlled heating region 62 for the mode of operation; Determining operating specifications for a reduced number of heating systems and then using a heating system with a reduced number of independently controlled heating zones. The data may include, by way of example, power level and/or temperature information, among other operational data from the heating system 10 having collected and recorded data.

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

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

Temperature values may be digitized and communicated to the microprocessor. The measured (sensed) temperature values can be compared to target (desired) temperatures for each region in step 108 . Then, at step 110, the power supplied to each heating unit is modulated based on the measured temperature to achieve the target temperature.

Optionally, the method may further comprise adjusting modulation power using a scaling factor. The scaling factor may be a function of the heating capacity of each heating zone. Controller 15 scales the dynamic behavior of the system to determine the amount of power that should be delivered to each region (via duty cycle, phase angle firing, voltage modulation, or similar techniques) between updates. Algorithms potentially involving factors and/or mathematical models (including knowledge of system update times) can be included. The desired power may be converted into a signal that is sent to a switch or other power modulating device for controlling the power output to the individual heating regions.

In this configuration, when at least one heating zone is turned off due to an abnormal condition, the remaining zones continue to provide the desired wattage without failure. Power is modulated to the functional heating zones to provide the desired wattage when an abnormal condition is detected in the at least one heating zone. When at least one heating zone is turned off based on the determined temperature, the remaining zones continue to provide the desired wattage. Power is modulated in each of the heating regions as a function of at least one of a received signal, a model, and a function of time.

For safety or process control reasons, typical heaters generally have specific limitations on the heater due to undesirable chemical or physical reactions at specific locations such as combustion/ignition/oxidation, coke boiling, etc. To prevent the location from exceeding a given temperature, it is operated below the maximum allowable temperature. Therefore, this is usually addressed by conservative heating designs (eg, large heating loads with low power densities and much lower heat fluxes than most of the surface area is capable of).

However, with the heating bundles of the present disclosure, it is possible to measure and limit the temperature at any location within the heater to a resolution on the order of the size of an individual heating zone. Hot spots large enough to affect the temperature of individual circuits can be detected.

Since the temperature of individual heating zones can be automatically adjusted and consequently limited, the dynamic and automatic limiting of the temperature of each zone can be achieved without fear of exceeding the desired temperature limit of any zone. Keep the area and all other areas operating at optimum power/heat flux levels. 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 modulate the power to individual zones can be selectively applied to individual heating zones rather than the entire heating assembly, thereby limiting predetermined temperature limits. reduce the risk of exceeding

Cartridge heater characteristics can change over time. This time-varying characteristic indicates that cartridge heaters are otherwise designed for a single selected (worst-case) flow regime, and thus are less susceptible to other flow conditions. It is required to operate under sub-optimal conditions.

However, dynamic control of the power distribution across the bundle to core size resolution by multiple heating units provided in the heating assembly allows for only one power distribution corresponding to only one flow condition in a typical cartridge heater. In contrast, optimized power distribution for various flow conditions can be achieved. Thus, the heating bundles of the present application allow for increased total heat flux for all other flow conditions.

In addition, variable power control allows for greater flexibility in heating design. Voltage can be separated (to a large extent) from resistance in the heating design, and the heater can be designed with the largest wire diameter that can fit into the heater. This allows increasing the capacity of power dissipation for a given heater size and reliability level (or heater life) and reduces the size of the bundle for a given overall power level. make it possible to The power in this configuration can be modulated by a variable duty cycle that is part of currently available or developing variable wattage controllers. The heating bundle can be protected by a programmable (or pre-programmed, if desired) limit to the duty cycle of a given area to prevent "overloading" the heating bundle.

8A-8D, the at least one heating assembly 50 described above is configured to provide variable power output per unit length along the length of the at least one heating assembly 50. An additional aspect of the disclosure is shown having a general structure. This variable power output can be implemented in various ways and in various combinations, some of which are shown and described herein by way of example. The physical structures described below may be provided in one or more heating units 52 and one or more heating assemblies 50 in any combination. Moreover, the additional teachings herein regarding variable power output may be combined with any of the foregoing aspects of the disclosure, individually or in any combination, while remaining within the scope of the disclosure.

In one form, shown in FIG. 8A, variable power output is provided by the physical construction of resistive heating elements 120 having variable pitches. As used herein, the term "pitch" refers to the pitch between the center points of successive turns of resistive heating element 120 along longitudinal direction X, as indicated by P1, P2, and P3 in this example. refers to the interval between As shown in this example, heating unit 52 has three distinct regions with different pitches P1, P2, and P3.

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

In yet another form, shown in FIG. 8C, variable power output is provided by a resistive heating element 120 having a variable cross-sectional area. This variable cross-sectional area may be provided with resistive heating elements 120 having different wire diameters D1, D2, and D3 as shown, or the wire diameter itself may be continuously variable along its length. (not shown). In another example not shown, if resistive heating element 120 is formed by a layered process, its thickness and/or width may vary for variable power output. This structure is shown in greater detail in U.S. Pat. No. 7,132,628, entitled "Variable Watt Density Stacked Heating System," commonly owned with the present application and incorporated herein by reference in its entirety. It is It should be understood that these and other variations that provide variable cross-sectional areas for the resistive heating element 120 should be construed to be within the scope of this disclosure.

Referring to a further example of FIG. 8D, a variable power output can comprise resistive heating elements 120 having both variable cross-sectional area and variable pitch. In this example, three different cross-sectional areas are used at diameters D1, D2, and D3, and three different pitches are used at pitches P1, P2, and P3. These examples and other combinations of different cross-sectional areas and pitches for providing variable power output within each heating unit 52 should be construed to be within the scope of this disclosure.

Referring now to FIG. 8E, at least one of another form of heating unit 52 uses different values of resistors R1, R2, R3, R4, and R5 for each resistive heating element 120 to provide variable power output. including multiple parallel circuits with In this configuration, each resistive heating element 120 is electrically connected in parallel across power conductor 42 . Alternatively, bus bars (not shown) may be used to connect the resistive heating elements 120 in parallel, where the bus bars are 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 used while remaining within the scope of the present disclosure other than those shown herein. 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 heating unit 52 has a different power distribution than adjacent heating units within a given heating assembly 50 . In another form, at least one heating unit 52 has independently controlled heating zones with variable power output in two or more heating assemblies 50 . It is understood that these may be used with heating bundles and heating assemblies, shown and described herein, among other variations shown herein for variable power output while remaining within the scope of this disclosure. want to be

In yet another form, variable power output may be achieved by using multiple heating elements. A composite heating element is made of a material that includes a material having a variable electrical resistivity along its length and is thus configured to provide a variable power output. As an example, the composite heating element of a heating unit has a higher electrical resistivity at one end (near the adjacent heating unit or near the edge of the heating assembly) and a higher electrical resistivity at the other end (another (near adjacent heating units facing each other) have a lower electrical resistivity.

Referring to FIG. 9, in another variation of the present disclosure, the physical structure comprises at least one heating unit 52 having a different cross-sectional area than adjacent heating units. Note that two or more heating units 52 may have different cross-sectional areas than other heating units, and one or more heating assemblies 50 may have heating units 52 with different cross-sectional areas. be understood. In combination with the modulation of power to the independently controlled heating regions as described above, these variable cross-sectional areas (in addition to other physical structures described herein) are independently controlled It is another way to create a large difference in power output along the length of the heating assembly 50 while decoupling the physical structure that provides the variable power output from the power value per unit area of the region.

Unless expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other properties are to be used in describing the scope of the present disclosure to be "about or "approximately". This change is desired for a variety of reasons, including industrial practice, material, manufacturing and assembly tolerances, and testability.

Spatial and functional relationships between elements are defined as "connected", "engaged", "coupled", "adjacent", "adjacent", "above", "above", Various terms are used to describe, including "above," "below," and "arranged." Unless expressly stated to be “direct,” when a relationship between a first element and a second element is described in this disclosure, that relationship is defined as the relationship between the first element and the second element. There can be a direct relationship between the two elements with no other intervening elements, and one or more elements (either spatially or functionally) between the first element and the second element. It can also be an indirect relationship with intervening elements. As used herein, the phrase at least one of A, B, and C should be interpreted to mean logic (A OR B OR C) using non-exclusive logic 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 present disclosure is merely exemplary in nature, and thus variations that do not depart from the content of the disclosure are intended to be within the scope of the disclosure. Such variations should not be considered a departure from the spirit and scope of this disclosure.

Claims (22)

A heating system,
a heating bundle,
a plurality of heating assemblies, at least one of said heating assemblies comprising a plurality of heating units, at least one heating unit having an independently controlled heating region, said at least one heating assembly comprising: a plurality of heating assemblies comprising a physical structure configured to deliver variable power output per unit length along the length of said at least one heating assembly;
a heating bundle comprising: a plurality of power conductors electrically connected to the plurality of heating units;
means for determining temperature;
power through the power conductors to the independently controlled heating regions based on the determined temperature to provide a desired power output along the length of the at least one heating assembly; a power supply including a controller configured to modulate;
A heating system, comprising: 2. The heating system of claim 1, wherein the physical structure comprises resistive heating elements within at least one heating unit having a variable pitch. 3. The heating system of claim 2, wherein said variable pitch is continuously variable along the length of said resistive heating element. 2. The heating system of claim 1, wherein the physical structure comprises resistive heating elements within at least one heating unit having a variable cross-sectional area. 2. The heating system of claim 1, wherein the physical structure comprises resistive heating elements within at least one heating unit having variable cross-sectional area and variable pitch. 2. The heating system of claim 1, wherein the physical structure includes multiple parallel circuits within at least one heating unit. 2. The heating system of claim 1, wherein the physical structure is provided on two or more of the plurality of heating units. The physical structure provides a higher electrical resistivity proximate an edge of an adjacent heating unit or the at least one heating assembly and a lower electrical resistivity proximate another opposing adjacent heating unit. 2. The heating system of claim 1, comprising a composite heating element having: 2. The heating system of claim 1, wherein the physical structure is provided on two or more of the heating assemblies. 2. The heating system of claim 1, wherein at least one heating assembly of said plurality of heating assemblies is a cartridge heater. 2. The heating system of claim 1, wherein the physical structure includes at least one heating unit having a different cross-sectional area than adjacent heating units. 2. The heating system of claim 1, wherein said heating unit comprises a plurality of resistive heating elements, at least one of said resistive heating elements acting as a sensor. 2. The heating system of claim 1, wherein said physical structure comprises a composite heating element having variable electrical resistivity. The variable electrical resistivity includes a higher electrical resistivity proximate an adjacent heating unit or end of the at least one heating assembly and a lower electrical resistivity proximate an opposing adjacent heating unit. 14. A heating system according to claim 13. A device for heating a fluid, comprising:
a sealed housing defining an interior chamber and having a fluid inlet and a fluid outlet;
and the heating system of claim 1, wherein the heating bundle is disposed within the interior chamber of the housing;
The apparatus of claim 1, wherein the heating bundle is adapted to provide a responsive heat distribution to fluid within the housing. A heating system,
a heating bundle,
a plurality of heating assemblies, at least one of said heating assemblies comprising a plurality of heating units, at least one heating unit having an independently controlled heating region, said at least one heating assembly comprising: a plurality of heating assemblies comprising a physical structure configured to deliver variable power output per unit length along the length of said at least one heating assembly;
a heating bundle comprising a plurality of power conductors electrically connected to the heating unit;
means for determining at least one of heating conditions and heating requirements;
said independently controlled power supply via said power conductors based on said at least one of heating conditions and heating requirements to provide a desired power output along the length of said at least one heating assembly; a power supply including a controller configured to modulate power to a heating region;
A heating system, comprising: said at least one of heating conditions and heating requirements is life of said heating unit, reliability of said heating unit, size of said heating unit, cost of said heating unit, flux of heater, characteristics and operation of said heating unit; 17. The heating assembly of claim 16, selected from the group consisting of power output, power input, and total heat generated. A device for heating a fluid, comprising:
a sealed housing defining an interior chamber and having a fluid inlet and a fluid outlet;
and the heating system of claim 16, wherein the heating assembly is disposed within the interior chamber of the housing;
The apparatus of claim 1, wherein the heating assembly is adapted to provide responsive heat distribution to fluid within the housing. A heating system,
A heating assembly comprising a plurality of heating units, wherein at least one heating unit has an independently controlled heating area, said heating assembly having a variable per unit length along the length of said heating assembly a heating assembly comprising a physical structure configured to deliver electrical power output;
a plurality of power conductors electrically connected to the heating unit;
to the independently controlled heating region 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 heating assembly. a power supply including a controller configured to modulate the power of
A heating system, comprising: 20. The heating system of claim 19, further comprising means for determining temperature. 20. The heating system of claim 19, further comprising means for determining heating conditions or requirements. A device for heating a fluid, comprising:
a sealed housing defining an interior chamber and having a fluid inlet and a fluid outlet;
and the heating system of claim 19, wherein the heating assembly is disposed within the interior chamber of the housing;
The apparatus of claim 1, wherein the heating assembly is adapted to provide responsive heat distribution to fluid within the housing.

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