TWI664873B - Heater bundle for adaptive control and method of reducing current leakage - Google Patents

Abstract

The present invention provides a method for controlling a heating system, which includes at least one heater assembly including a plurality of heater units, each heater unit defining at least one independently controlled heating area, and being electrically connected to The electrical conductors of each of the individually controlled heating areas in each of the heater units supply power to each of the heater units and modulate the power supplied to each of the individually controlled heating areas. A voltage is selectively supplied to each of the independently controlled heating regions, such that a reduced number of independently controlled heating regions receive the voltage at one time, or at least a subset of the independently controlled heating regions receive a reduced voltage at any time.

Description

Heater bundle for adaptive control and method for reducing current leakage

This disclosure is related to electric heaters, and more specifically to heaters that heat a fluid flow, such as heat exchangers, and methods of controlling the same.

The statements in this paragraph merely provide background information about the present disclosure and may not constitute conventional technology.

A fluid heater may be in the form of a cassette heater having a drawbar configuration to heat fluid flowing along or through an external surface of the cassette heater. The cassette heater may be disposed inside a heat exchanger to heat a fluid flowing through the heat exchanger. If the cassette heater cannot be properly sealed, moisture and fluid will enter the cassette heater and contaminate it. A resistance heating element and the metal sheath of the cassette heater are used as an electrically insulating insulating material, causing dielectricity. Quality damage and inevitable heater failure. The moisture can also cause a short circuit between the electrical conductor and the outer metal sheath. Failure of the cassette heater can cause costly downtime for devices using the cassette heater.

In addition, some heaters experience "current leakage" during operation, which is generally a current passing to a ground. This current leaks through insulated surrounding conductors in the electric heater, and this condition causes voltage rise and overheating.

In one form of the present disclosure, a method for controlling a heating system is provided. The method includes providing at least one heater assembly, the heater assembly includes a plurality of heater units, and each heater unit defines at least one independent Controlled heating area. Power can be supplied to each of these heater units through electrical conductors electrically connected to each of those individually controlled heating areas in each of these heater units, and the power is modulated to each of these individually controlled units Heating zone, a voltage is selectively supplied to each of these independently controlled heating zones, so that a reduced number of independently controlled heating zones receive the voltage at one time, or at least a part of the independently controlled heating zones receive at any time a Reduce the voltage.

In another form, it provides a method of reducing current leakage in a heating system, the method comprising providing at least one heater assembly, the heater assembly comprising a plurality of heater units, each heater unit defining at least one Independently controlled heating zones, supplying electrical power to each such heater unit through electrical conductors electrically connected to each such individually controlled heating zone in each such heater unit, and modulating supply to each The power of one of the independently controlled heating areas, wherein a voltage is selectively supplied to each of the independently controlled heating areas, so that the total area of one of the independently controlled heating areas that receives a voltage at a time is reduced, or At least a portion of the independently controlled heating zone receives a reduced voltage at any time.

In another form, it provides a heater system including a heater bundle having a plurality of heater assemblies, each heater assembly including a plurality of heater units, each heater unit defining at least An independently controlled heating zone and electrical conductors electrically connected to each of the individually controlled heating zones in each of the heater units. An electric power supply device is arranged to modulate electric power to each of the individually controlled heating areas of the heater units through the electric conductors, and a voltage is selectively supplied to each of the individually controlled heating areas, A reduced number of independently controlled heating zones is allowed to receive the voltage at one time, or at least a portion of the independently controlled heating zones are to receive a reduced voltage at any time.

In yet another form, it provides a heater system including a heater assembly having a plurality of heater units, each heater unit defining at least one independently controlled heating area. An electric conductor is electrically connected to each of the individually controlled heating areas in each of the heater units, and a power supply device is configured to modulate electricity to each of the heater units through the electric conductors. These independently controlled heating zones. A voltage is selectively supplied to each of the independently controlled heating zones, such that a reduced number of independently controlled heating zones receive the voltage at one time, or at least a portion of the independently controlled heating zones receive a reduced voltage at any time.

Other aspects of applicability will become more apparent from the description provided herein. It should be understood that these descriptions and specific examples are intended as illustrations only and are not intended to limit the scope of this disclosure.

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

Referring to FIG. 1, a heater system constructed in accordance with the teachings of the present disclosure is generally designated by reference numeral 10. The heater system 10 includes a heater bundle 12 and a power supply device 14 electrically connected to the heater bundle 12. The power supply device 14 includes a controller 15 for controlling the power supply of the heater bundle 12. As used in this disclosure, a "heater bundle" refers to a heater device that includes two or more physically separate heating devices that can be controlled independently. Therefore, when one of the heating devices in the heater bundle fails or is degraded, 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 fixed to the mounting flange 16. The mounting flange 16 includes a plurality of apertures 20 extending across the heater assemblies 18. Although the heater assemblies 18 are configured in parallel in this form, it should be understood that the alternate positions / arrangements of the heater assemblies 18 are still within the scope of this disclosure.

As shown additionally, the mounting flange 16 includes a plurality of mounting holes 22. By using screws or bolts (not shown) to pass through the mounting holes 22, the mounting flange 16 can be assembled to a wall carrying a fluid to heat a duct or a delivery pipe (not shown). In the form of this disclosure, at least a portion of the heater assemblies 18 may be immersed in a fluid inside the conduit or duct to heat the fluid.

Referring to FIG. 2, the heater assembly 18 according to one form may be in the form of a cassette heater 30. The cassette heater 30 is a tube heater, which generally includes a core body 32, a resistance heating circuit 34 surrounding the core body 32, and a metal sheath surrounding the core body 32 and the resistance heating circuit 34. 36, and an insulating material 38 filling the space in the metal sheath 36 to electrically isolate the resistance heating circuit 34 from the metal sheath 36, and thermally conduct the thermal energy from the resistance heating circuit 34 to the metal sheath Set of 36. The core body 32 may be made of ceramic. The insulating material 38 may be dense magnesium oxide (MgO). A plurality of electrical conductors 42 extend through the core body 32 in a longitudinal direction and are electrically connected to the resistance heating circuit 34. The electrical conductors 42 also extend through an end piece 44 that seals the outer sheath 36. The electrical conductors 42 are connected to an external power supply device 14 (as shown in FIG. 1) to supply power from the external power supply device 14 to the resistance heating line 32. Although FIG. 2 shows that only two electrical conductors 42 extend through the end piece 44, more than two electrical conductors 42 may extend through the end piece 44. The electrical conductors 42 may be in the form of conductive pins. The various constructions and other structural and electrical details of the cassette heater can be listed in more detail in US Patent Nos. 2,831,951 and 3,970,822, which are commonly assigned with this application and their contents are incorporated herein by reference for all purposes. Therefore, it should be understood that the forms described herein are merely examples and should not be construed as limiting the scope of the disclosure.

Alternatively, multiple resistance heating circuits 34 and multiple pairs of electrical conductors 42 may be used to form multiple heating circuits that can be independently controlled to enhance the reliability of the cassette heater 30. Thus, when one of the resistance heating circuits 34 fails, the remaining resistance circuits 34 can continue to generate thermal energy without causing the entire cassette heater 30 to fail and without causing costly machine downtime.

Referring to FIGS. 3 to 5, the heater assemblies 50 may be in the form of a box heater having a configuration similar to that of FIG. 2 except that the number of core bodies and the number of electrical conductors are used. More specifically, each of the heater assemblies 50 includes a plurality of heater units 52, and an outer metal sheath 54 surrounding one of the plurality of heater units 52, and a plurality of electrical conductors 56. An insulating material (not shown in FIGS. 3 to 5) is disposed between the plurality of heater units 52 and the outer metal sheath 54 so as to electrically isolate the heater units 52 from the outer metal sheath 54. . Each of the plurality of heater units 52 includes a core body 58 and a resistance heating element 60 surrounding the core body 58. The resistance heating element 60 of each heater unit 52 may define one or more heating circuits to define one or more heating regions 62.

In this form, each heater unit 52 defines a heating area 62 and the plurality of heater units 52 of each heater assembly 50 are aligned in a longitudinal direction X. Therefore, each heater assembly 50 defines a plurality of heating regions 62 collimated along the longitudinal direction X. The core body 58 of each heater unit 52 defines a plurality of through holes / apertures 64 to allow the electrical conductor 56 to extend therethrough. The resistance heating elements 60 of the heater units 52 are connected to the electrical conductors 56, which in turn are connected to an external power supply device 14. The electrical conductors 56 supply power from the power supply device 14 to the plurality of heater units 50. By appropriately connecting the electric conductors 56 to the resistance heating elements 60, the resistance heating elements 60 of the plurality of heater units 52 can be independently controlled by the controller 15 of the power supply device 14. For its part, the failure of one of the resistance heating elements 60 for a specific heating region 62 will not affect the proper function of the remaining resistance heating elements 60 of the remaining heating regions 62. In addition, in order to facilitate maintenance or assembly, the heater units 52 and the heater assemblies 50 are interchangeable.

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

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

Alternatively, a larger number of electrically separated heating regions 62 may be established by the controller 15 of the external power supply device 14 through the topology of multiplexing, polarity-sensitive switching, and other circuits. The use of thermal array multiplexing or various configurations to increase the number of cartridge heaters 50 for a given number of electrical conductors (e.g., one cartridge heater with six electrical conductors for 15 or 30 zones) The number of heating zones can be disclosed in US Patent Nos. 9,123,755, 9,123,756, 9,177,840, 9,196,513, and related applications, which are jointly assigned with this application and their contents are incorporated herein by reference for all purposes.

Due to this structure, each heater assembly 50 includes a plurality of heating regions 62 that can be independently controlled to change 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. Thus, the heater bundle 12 provides a plurality of heating regions 62 and an adjusted heat distribution for heating the fluid flowing through the heater bundle 12 to suit a particular application. The power supply device 14 can be configured to modulate power to each of these individually controlled heating zones 62.

For example, a heating assembly 50 may define an "m" heating zone, and the heater bundle may include "k" heater assemblies 50. Therefore, the heater bundle 12 may define m ^× k heating regions. The plurality of heating regions 62 in the heater bundle 12 may be used to respond to heating conditions and / or heating requirements, including, but not limited to, the life and reliability of the individual heater units 52, The size and cost, the local heater flux, the characteristics and operation of these heater units 52, and the overall power output are individually and dynamically controlled.

Each circuit can be individually controlled at a required temperature or a required power level so that the temperature and / or power distribution is adapted to the changing pattern in the system parameters (e.g., manufacturing changing pattern / tolerance, changing Environmental conditions, changing inlet flow conditions, such as inlet temperature, inlet temperature distribution, flow velocity, velocity distribution, fluid synthesis, fluid heat capacity, etc.). More specifically, when the heater units 52 are operated at the same power level, the same heat output may not be generated due to manufacturing variations and changes in the degree of heater degradation over time. The heater units 52 can be independently controlled to adjust the heat output according to a desired heat distribution. The individual manufacturing tolerances of the components of the heater system and the assembly tolerances of the heater system increase as a function of the modulation power of the power supply, or in other words, due to the high fidelity of heater control, individual components The manufacturing tolerances need not be so tight / narrow.

Each of the heater units 52 includes a temperature sensor (not shown) for measuring the temperature of the heater units 52. When a hot spot of the heater units 52 is detected, the power supply device 14 can reduce or turn off the power provided to the specific heater unit 52 detected by the hot spot to prevent the specific heater unit 52 from overheating or Failure. The power supply device 14 may modulate the power to a heater unit 52 adjacent to the disabled heater unit 52 to compensate for the reduced heat output from the specific heater unit 52.

The power supply device 14 may include multiple area algorithms to turn off or lower the level of power delivered to any specific area, and increase delivery to a heating area adjacent to a specific heating area that is disabled and has a reduced heat output. Its electricity. By carefully adjusting the power to each heating zone, the overall reliability of the system can be improved. Therefore, by detecting the hot spot and controlling the power supply, the heater system 10 has improved safety.

The heater bundle 12 having the plurality of independently controlled heating regions 62 can perform improved heating. For example, certain circuits on the heater units 52 may operate for less than 100% of a nominal (or "typical") duty cycle (or an average power portion of a portion of the power generated by a heater with an applied line voltage) Level). This lower duty cycle allows the use of a resistance heating circuit with a larger diameter, thereby improving reliability.

Conventionally, a smaller area can use a better circuit size to achieve a given resistance. Variable power control allows the use of a larger line size and can be adapted to a lower resistance value, while protecting the heater from overload with a duty cycle limitation that combines the power consumption capacity of the heater.

The use of a scale factor can be combined with the capacity of the heater units 52 or the heating area 62. The plurality of heating zones 62 allow more precise determination and control of the heater bundle 12. Using a specific scaling factor for a specific heating circuit / area may allow a more active (i.e., higher) temperature (or power level) on almost all areas, which is directed toward a smaller for the heater bundle 12 Low-cost design. This type of scale factor and method can be disclosed in US Patent No. 7,257,464, which is co-assigned with this application and its contents are incorporated herein for comprehensive reference.

The size 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 temperature or power distribution to a desired accuracy.

Referring again to FIG. 1, the heater assemblies 18 are shown as a single-end heater, that is, the conductive pin extends only through one of the longitudinal ends of the heater assemblies 18. The heater assembly 18 may extend through and be sealed to the mounting flange 16 or a partition (not shown). As such, the heater assemblies 18 can be individually removed and replaced without removing the mounting flange 16 from the conduit or duct.

Alternatively, the heater assembly 18 may be an "two-end" heater. In a two-end heater, the metal sheath is bent into a hairpin shape, and the electrical conductors pass through the two longitudinal ends of the metal sheath, so that the two longitudinal ends of the metal sheath pass through and are sealed to the projection. Edge or bulkhead. In this architecture, before the individual heater assembly 18 is replaced, the flange or the partition needs to be removed from the housing or the duct.

Referring to FIG. 6, a heater bundle 12 is incorporated into a heat exchanger 70. The heat exchanger 70 includes a sealed housing 72 defining an internal chamber (not shown), and a heater bundle 12 disposed in the internal chamber of the housing 72. The sealing housing 72 includes a fluid inlet 76 and a fluid outlet 78 for introducing or discharging fluid into or from an inner chamber of the sealing housing 72. The fluid is heated by a heater bundle 12 provided in the sealed housing 72. The heater bundle 12 may be configured for a cross flow or a flow parallel to its length.

The heater bundle 12 is connected to an external power supply device 14, which may include a device for modulating power, such as a switching device or a variable transformer to modulate the power supplied to another area. The power modulation can be performed as a function of time or based on the detected temperature of each heating zone.

The resistance heating circuit can also be used as a sensor, which uses the resistance of the resistance circuit to measure the temperature of the resistance circuit and uses the same electrical conductor to transmit temperature measurement information to the power supply device 14. One temperature sensing device in each zone may allow temperature control along the length of each heater assembly 18 in the heater bundle 12 (analysis down to individual zones). Therefore, additional temperature sensing circuits and sensing devices can be eliminated, thereby reducing the manufacturing cost. When attempting to maximize the heat flux in a given circuit while maintaining one of the required reliability levels of the system, direct measurement of the temperature of the heater circuit is a significant advantage because it can eliminate or minimize and use Many measurement errors are associated with a separate sensor. This heating element temperature is a characteristic that has the greatest influence on the reliability of the heater. The use of a resistive element as both a heater and a sensor is disclosed in US Patent No. 7,196,295, which is co-assigned with this application and the contents of which are incorporated herein by reference in its entirety.

Alternatively, the electrical conductors 56 can be made of different metals so that the electrical conductors 56 of different metals can establish a thermal coupling to measure the temperature of the resistance heating elements. For example, a power supply and a power return conductor of at least one set may include different materials such that a junction is formed between the different materials, and a resistance heating element of a heater unit is used to determine one or more areas Of temperature. Using "integrated" and "highly thermally coupled" sensing, such as using different metals for the heater, results in a similar thermally coupled signal. The use of this integrated and coupled electrical conductor for temperature measurement may be disclosed in US Application No. 14 / 725,537, which is co-assigned with this application and its contents are incorporated herein by reference for all purposes.

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

The heater units 52 disclosed herein can also be calibrated using various methods, including but not limited to energizing and sampling each heater unit 52 to calculate its resistance. The calculated resistance can then be compared with a calibrated resistance to determine a resistance ratio, or a value for later determining the actual heater unit temperature. Exemplary methods may be disclosed in US Patent Nos. 5,280,422 and 5,552,998, which are commonly assigned with this application and the contents of which are incorporated herein by reference for all purposes.

A form of calibration includes operating the heater system 10 in at least one operating mode, controlling the heater system 10 to generate a desired temperature for at least one of the independently controlled heating zones 62, and heating for the at least one independently controlled The area 62 collects and records data for the operation mode, and then accesses the recorded data to determine the operating specifications of a heating system with a reduced number of independently controlled heating areas, and subsequently uses the individually controlled heating area with the reduced number Heating system. By way of example, among other operational data of the heater system 10 from which its data is collected and recorded, the data may include power level and / or temperature information.

In a variation of this disclosure, the heater system may include a single heater assembly 18 instead of multiple heater assemblies in a heater bundle 12. The single heater assembly 18 may include a plurality of heater units 52, and each heater unit 52 defines at least one independently controlled heating area. Similarly, the electric conductors 56 are electrically connected to each of the individually controlled heating areas 62 in each of the heater units 62, and the power supply device is configured to modulate power to the heaters through the electric conductors 56 Each of these individually controlled heating zones 62 of the unit.

Referring to FIG. 7, in step 102, a method 100 of controlling a heater system includes providing a heater bundle including 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 subsequent heating zones). In step 104, power to each of the heater units is supplied through electrical conductors electrically connected to each of the individually controlled heating zones in each of the heater units. The temperature in each of these areas is detected in step 106. The temperature may be determined using a resistance change of a resistance heating element of at least one of the heater units. The zone temperature can be initially determined by measuring the zone resistance (or the circuit voltage measurement if appropriate materials are used).

These temperature values can be digitized. In step 108, the signals can be passed to a microprocessor. The measured (detected) temperature value can be compared with a target (required) temperature for each zone. In step 110, the power supplied to each of the heater units can be adjusted based on the measured temperature to reach the target temperature.

Alternatively, the method may further include using a scale factor to adjust the modulation power. The scaling factor can be a function of the heating capacity of each heating zone. The controller 15 may include an algorithm that potentially includes a scale factor and / or a mathematical model of the system's dynamic behavior (including knowledge of the system's update time) to determine (excitation via duty cycle, phase angle) , Voltage modulation or similar technology) to provide power to each area until the next update. The required power can be converted into a signal, which is transmitted to a switch or other power modulation device for controlling the power output of the individual heating area.

In this form, when at least one heating zone is closed due to an abnormal condition, the remaining zones continue to provide a required wattage without failing. When an abnormal condition is detected in at least one heating zone, the power can be adjusted to a functional heating zone to provide a required wattage. When at least one heating zone is turned off based on the determined temperature, the remaining zones continue to provide a required wattage. The power can be adjusted to each of the heating regions as a function of the received signal, at least one of a model, and as a function of time.

For safety and process control reasons, typical heaters generally operate below a maximum allowable temperature to prevent a particular location of the heater from chemical or physical reactions that are not needed in that particular location, such as combustion / excitation / oxidation , Coking boiling, etc. above a given temperature. Therefore, this is typically provided by a conservative heater design (e.g., a large heater with a low power density, and many of its surface areas are loaded with a heat flux that is much lower than could be achieved otherwise).

However, due to the heater bundle of this disclosure, it can measure and limit the analysis of the temperature of any location in the heater down to the level of the size of the individual heating zones. A hot spot that is large enough to affect the temperature of another circuit can be detected.

Because the temperature of these individual heating zones can be adjusted automatically and therefore limited, the dynamic and automatic limits of the temperature in each zone can operate this zone and all other zones at an optimal power / heat flux level Without worrying about any area exceeding the required temperature limit. This brings an advantage in high limiting temperature measurement accuracy beyond the current implementation of a jacket that clamps a separate thermal coupling to one of the elements in a heater bundle. This ability to reduce boundaries and modulate the power to individual areas can be selectively applied to such heating areas, selectively and individually, rather than to a full heater assembly, thereby reducing the risk of exceeding a predetermined temperature limit .

The characteristics of the cassette heater can be changed over time. This time-varying characteristic would otherwise require the cassette heater to be designed for a single-choice (poor) flow state, and thus the cassette heater could be operated in a good state for other flow states.

However, because of the dynamic control of power distribution across the entire heater bundle due to the multiple heating units provided in the heater assembly down to the analysis of the core size, the comparison is relative to that of a typical cassette heater There is only one power distribution in only one flow state, which can achieve the best power distribution for one of various different flow states. Thus, for all other flow states, the heater bundle of the present application allows this overall heat flux to be increased.

In addition, variable power control increases the flexibility of the heater design. This voltage can be (substantially) decoupled from the heater design and the heaters can be designed to fit the maximum line diameter of the heater. This allows for increased capacity for a given heater size and reliability level (or lifetime of the heater) power distribution, and allows the size of the heater bundle to be reduced for a given overall power level. The power in this configuration can be adjusted by a variable duty cycle as part of a variable wattage controller currently available or under development. For a given area, the heater bundle may be protected by a programmable (or pre-planned if necessary) limited to the duty cycle to prevent "overloading" the heater bundle.

In another form of the present disclosure, it provides a method and apparatus for reducing current leakage. A method of controlling a heating system includes providing at least one heater assembly including a plurality of heater units, each heater unit defining at least one independently controlled heating zone as described above. Electricity is supplied to each of the heater units through electrical conductors electrically connected to each of the individually controlled heating zones in each of the heater units, and the supplied electricity is modulated to each of the independent heater units. Controlled heating area. In order to reduce current leakage, a voltage from the power supply is selectively supplied to each of these independently controlled heating areas, so that a reduced number of independently controlled heating areas receive the voltage at one time, or the independently controlled heating areas At least a portion (or a subset) of them receives a reduced voltage at any time. In one example, the voltage may be selectively supplied by a variable transformer.

These independently controlled areas can be switched continuously so as to limit the number of this area (the cross-sectional area of the electrical insulation that is exposed to the potential). By limiting the number of regions (and the area) that will receive the potential at any given time to a small fraction of the total number of such regions, we can reduce current leakage by a similarly small fraction. For example, if the areas in a heater bundle are divided into four groups (not geometrically continuous) and if each such group covers approximately 1/4 of the total area of the heater, and further If the switching scheme is configured such that no more than one of the four areas is instantaneously powered on at any given time, the overall leakage current from the heater can be reduced by a factor of 4 (to its initial value of 25 %).

To accomplish this selective voltage supply, a scale factor is used in a form. This scale factor can be used in accordance with the teachings of US Patent No. 7,257,464, which is commonly assigned with this application and its entire contents are incorporated herein by reference for all purposes. The scale factor may be used for at least one of adjusting the modulation power, determining an amount of voltage of the selective supply, and determining at least one duration of the selective supply of voltage.

In addition, the scale factor may be a function of the operating characteristics of the heating system. For example, the scaling factor may be a function of the power consumption capacity of at least one independently controlled heating zone, the maximum allowable temperature of at least one independently controlled heating zone, and one of the at least one independently controlled heating zone exposed. Heating area, a thermal behavior model of the heating system, characteristics of an environmental system that generates fluid flow heated by the heater system, a fluid flow rate across the heater assembly, one of at least one independently controlled heating zone Area, electrical insulation resistance of at least one independently controlled heating area, current leakage in at least one independently controlled heating area, circuit resistance in at least one independently controlled heating area, area circuit EMF in at least one independently controlled heating area , And a dielectric constant of at least one independently controlled heating region, and so on.

In another form, the scale factor is a power limit function that is used to select one of the wattage, the amount of selective supply voltage, and the duration of the selective supply of voltage to each heating zone. The value is limited to less than a plurality of values generated by using a scale function at a complete line voltage. The scale function is a ratio between a desired value and the value of the complete line voltage. One of the power controllers can Multiplying the percentage output by the scale function provides a scale output.

The sequence and / or location of the independently controlled heating zones for which the voltage is continuously supplied can be any variation depending on the application requirements. For example, the voltage may be continuously supplied before a peripheral area, or near the edge of a heater, before being supplied to other geometric areas of the independently controlled heating area. In addition, the voltage may be continuously supplied to different heating regions based on a change in resistance of each heating region.

In another form, at least one heating zone is turned off based on an abnormal condition, while the remaining zones continue to selectively receive voltage.

In another form, a ratio of continuously supplying the voltage to each of the heating regions is adjusted based on an operating characteristic of at least one heating region. By way of example, these operating characteristics may be: changes in resistance, temperature, and resistance over time of at least one heating zone; a fluid flow rate across the heater assembly; an area of at least one independently controlled heating zone; Electrical insulation resistance of at least one independently controlled heating zone; current leakage in one of at least one independently controlled heating zone; circuit resistance in at least one independently controlled heating zone; at least one independently controlled heating zone zone circuit EMF; at least The dielectric constant of an independently controlled heating zone; and the characteristics of an environmental system that produces a fluid flow heated by the heater system.

The method of reducing leakage current according to the form of the present disclosure may also be applied to at least one heater assembly including a plurality of heater units, each heater unit defining at least one independently controlled heating area. These methods may be used with any of the embodiments of heaters and heater systems disclosed herein, while remaining within the scope of this disclosure.

It should be noted that the present disclosure is not limited to the embodiments as illustrated and illustrated. Various modifications have been described in this article and are more part of the knowledge of the industry. These and other modifications and any substitution of technically equivalent elements may be added to the description and graphics without departing from the disclosure and the scope of protection of this patent.

10‧‧‧ heater system

12‧‧‧ heater bundle

14‧‧‧ (external) power supply unit

15‧‧‧controller; closed loop automatic control system

16‧‧‧Mounting flange

18‧‧‧Heating (device) assembly

20‧‧‧ Aperture

22‧‧‧Mounting holes

30‧‧‧ Cassette heater

32, 58‧‧‧ Core Ontology

34‧‧‧Resistance (heating) line

36‧‧‧ (metal) sheath

38‧‧‧Insulation material

42, 56‧‧‧ electric conductor

44‧‧‧ end piece

50‧‧‧heater assembly

52‧‧‧heater unit

54‧‧‧ Outer metal sheath

60‧‧‧ resistance heating element

62‧‧‧heated area

64‧‧‧through hole / aperture

70‧‧‧ heat exchanger

72‧‧‧Sealed cover

76‧‧‧fluid inlet

78‧‧‧fluid outlet

100‧‧‧ Method

102, 104, 106, 108, 110‧‧‧ steps

X‧‧‧ Longitudinal

In order to better understand the present disclosure, it will now explain the various forms given by examples and with reference to the following drawings, in which:

1 is a perspective view of a heater bundle constructed according to the teachings of the present disclosure;

2 is a perspective view of a heater assembly of the heater bundle of FIG. 1;

3 is a perspective view of a variation of a heater assembly of the heater bundle of FIG. 1;

4 is a perspective view of the heater assembly of FIG. 3, in which the outer sheath of the heater assembly is clearly shown;

5 is a perspective view of a core body of the heater assembly of FIG. 3;

FIG. 6 is a perspective view of a heat exchanger including the heater bundle of FIG. 1, where the heater bundle is partially disassembled from the heat exchanger to illustrate the heater bundle for illustration; and

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.

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

Claims (20)

A method of controlling a heater system, comprising: providing at least one heater assembly including a plurality of heater units and surrounding the plurality of heater units to electrically insulate the plurality of heater units An insulating material, each heater unit defining at least one independently controlled heating area; and an electrical conductor electrically connected to each of these individually controlled heating areas in each of these heater units, supplying power to each A heater unit; and modulating the power supplied to each of the independently controlled heating zones, a voltage being selectively supplied to each of the individually controlled heating zones, such that a reduced number of the independently controlled heating zones The controlled heating area receives the voltage at one time, or at least a subset of the independently controlled heating areas receives a reduced voltage at any time, and reduces the overall leakage current through the insulating material. The method of claim 1, further comprising using a scale factor to perform at least one of the following actions: adjusting the modulation power, determining an amount of voltage to be selectively supplied, and determining a duration of the voltage selective supply . The method of claim 2, further comprising using the scaling factor as a function of at least one of the following: the power consumption capacity of at least one independently controlled heating area, and the maximum allowable one of at least one independently controlled heating area Temperature, exposed heating area of at least one independently controlled heating area, thermal behavior model of the heater system, characteristics of an environmental system generating fluid flow heated by the heater system, crossing one of the heater assemblies Fluid flow rate, area of at least one independently controlled heating area, electrical insulation resistance of at least one independently controlled heating area, current leakage of at least one independently controlled heating area, circuit resistance of at least one independently controlled heating area A region circuit EMF of at least one independently controlled heating region, and a dielectric constant of at least one independently controlled heating region. The method of claim 2, wherein the scale factor is a power limit function, which is used to calculate the number of watts, the amount of selective supply voltage, and the duration of the selective supply of voltage to each heating zone A value, limited to less than a plurality of values generated by using a scale function at a full line voltage, the scale function being a ratio between a desired value and the value of the full line voltage, one of which is a power controller A percentage output is obtained by multiplying this value with the scale function. The method of claim 1, wherein the voltage is continuously supplied to a predetermined geometric region of the independently controlled heating regions. The method of claim 1, wherein the voltage is continuously supplied to different heating regions based on a change in resistance of each heating region. As in the method of claim 1, at least one of the heating regions is turned off based on an abnormal condition, and the remaining regions continue to selectively receive voltage. The method of claim 1, wherein the ratio of continuously supplying the voltage to each of the heating zones is adjusted based on an operating characteristic of at least one heating zone. The method of claim 8, wherein the operating characteristic is one of the following: changes in resistance, temperature, and resistance over a period of time in at least one heating zone; a fluid flow rate across the heater assembly; at least one independent control Area of one of the heating zones; electrical insulation resistance of at least one independently controlled heating zone; current leakage in at least one independently controlled heating zone; circuit resistance of at least one independently controlled heating zone; at least one independently controlled heating zone A zone circuit EMF; a dielectric constant of at least one independently controlled heating zone; and characteristics of an environmental system generating a fluid flow heated by the heater system. A method for reducing current leakage in a heater system, comprising: providing at least one heater assembly, the heater assembly including a plurality of heater units and surrounding the plurality of heater units to heat the plurality of heaters An insulating material that electrically isolates the heater unit, and each heater unit defines at least one independently controlled heating area; through an electrical conductor that is electrically connected to each such individually controlled heating area in each such heater unit, Electric power is supplied to each of these heater units; and electric power supplied to each of these independently controlled heating areas is modulated, and a voltage is selectively supplied to each of these independently controlled heating areas, so that the voltage is received at one time The total area of one of the independently controlled heating regions is reduced, or at least a subset of the independently controlled heating regions receive a reduced voltage at any time, and the overall leakage current through the insulating material is reduced. The method of claim 10, wherein the voltage is continuously supplied to a predetermined geometric area of the independently controlled heating areas. The method of claim 10, wherein the voltage is continuously supplied to different heating areas based on a change in resistance of each heating area. The method of claim 10, wherein at least one of the heating regions is turned off based on an abnormal condition, and the remaining regions continue to selectively receive voltage. The method of claim 10, wherein a ratio of continuously supplying the voltage to each of the heating zones is adjusted based on an operating characteristic of at least one heating zone. A heater system includes: a heater bundle including: a plurality of heater assemblies, each heater assembly including a plurality of heater units and surrounding the plurality of heater units so that the plurality of An insulating material that is electrically insulated by a heater unit, each heater unit defining at least one independently controlled heating area; and an electrical conductor that is electrically connected to each such individually controlled heating area in each such heater unit And an electric power supply device configured to modulate electric power to each of the individually controlled heating areas of the heater units through the electric conductors, wherein a voltage is selectively supplied to each of the individually controlled heating areas Heating zone, such that a reduced number of independently controlled heating zones receive the voltage at one time, or at least a subset of the independently controlled heating zones receive a reduced voltage at any time, so that the overall leakage current through the insulating material cut back. The heater system of claim 15, wherein the voltage is selectively supplied via a variable transformer. The heater system of claim 15, wherein at least one set of a power supply and a power return conductor contains different materials so that a junction is formed between the different materials and a resistance heating element of a heater unit And is used to determine the temperature in one or more areas. For example, the heater system of claim 15, wherein the number of the heating areas is n, and the number of the electric conductors is n + 1, where n is a natural number. A device for heating a fluid, comprising: a sealed enclosure defining an internal cavity having a fluid inlet and a fluid outlet; and a heater bundle as claimed in claim 15 provided in the internal cavity of the enclosure A chamber, wherein the heater bundle is adapted to provide an adjusted heat distribution to a fluid in the housing. A heater system includes: a heater assembly including a plurality of heater units and an insulating material surrounding the plurality of heater units to electrically insulate the plurality of heater units, each heater The unit defines at least one independently controlled heating area; an electrical conductor electrically connected to each of the individually controlled heating areas in each of the heater units; and a power supply device configured to pass through the electricity The conductor modulates power to each of the individually controlled heating zones of the heater unit, and a voltage is selectively supplied to each of the individually controlled heating zones, so that a reduced number of independently controlled heating zones are provided at one time. Receiving the voltage, or at least a subset of the independently controlled heating areas, receives a reduced voltage at any time and reduces the overall leakage current through the insulating material.