Note: Descriptions are shown in the official language in which they were submitted.
HEATER BUNDLES HAVING VIRTUAL SENSING FOR THERMAL GRADIENT
COMPENSATION
FIELD
[0001] The present disclosure relates to electric heaters, and more
particularly to
heaters for heating a fluid, such as a fluid within heat exchangers.
BACKGROUND
[0002] The statements in this section merely provide background
information
related to the present disclosure and may not constitute prior art.
[0003] A fluid heater may be in the form of a cartridge heater, which has
a rod
configuration to heat fluid that flows along or past an exterior surface of
the cartridge
heater. The cartridge heater may be disposed inside a heat exchanger for
heating the
fluid flowing through the heat exchanger. If the cartridge heater is not
properly sealed,
moisture and fluid may enter the cartridge heater to contaminate the
insulation material
that electrically insulates a resistive heating element from the metal sheath
of the
cartridge heater, resulting in dielectric breakdown and consequently heater
failure. The
moisture can also cause short circuiting between power conductors and the
outer metal
sheath. The failure of the cartridge heater may cause costly downtime of the
apparatus
that uses the cartridge heater.
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Date Recue/Date Received 2022-03-09
SUMMARY
[0004] This section provides a general summary of the disclosure and is
not a
comprehensive disclosure of its full scope or all of its features.
[0005] The present disclosure provides a heater system that includes a
heater
bundle with at least one heater assembly having a plurality of heater units,
at least one of
the heater units defining at least one independently controlled heating zone.
A plurality
of power conductors are electrically connected to the heater units, and a
power supply
device includes a controller configured to modulate power to the at least one
independently controlled heating zone through the power conductors. The
controller is
configured to calculate temperature within the at least one heater unit based
on a
predefined model and at least one input, and the controller modulates power to
the at
least one heater unit based on the calculated temperature.
[0006] In variations of this heater system, which may be implemented
individually
or in any combination: the at least one heater unit is an end heater unit; the
at least one
input comprises temperature at another location within the heater bundle; the
at least one
input comprises at least one temperature of at least one of the plurality of
heater units;
the at least one input comprises power consumption of the heater bundle; the
at least one
input comprises average power consumption of the heater bundle over a
predetermined
time period; the at least one input comprises a voltage of the heater bundle
and/or a
voltage of at least one of the heater units; the at least one input comprises
a current of
the heater bundle and/or a current of at least one of the heater units; the at
least one input
comprises a current leakage of the heater bundle; the at least one input
comprises an
insulation resistance of the heater bundle; the at least one input comprises
at least one
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Date Recue/Date Received 2022-03-09
of a fluid temperature, a fluid speed, a fluid velocity, and a fluid mass flow
rate; the
controller calculates temperature by supplying a known current to the
plurality of heater
units, measuring a voltage of the at least one independently controlled
heating zone, and
comparing the measured voltage to a nominal voltage associated with the known
current
to identify voltage deviations and/or corresponding resistance deviations; and
the
controller calculates temperature by supplying a known voltage to the
plurality of heater
units, measuring a current of the at least one independently controlled
heating zone, and
comparing the measured current to a nominal current associated with the known
voltage
to identify current deviations and/or corresponding resistance deviations.
[0007] In another variation of this heater system, an apparatus for
heating fluid
comprises a sealed housing defining an internal chamber and having a fluid
inlet and a
fluid outlet, and the at least one heater assembly is disposed within the
internal chamber
of the housing. The at least one heater assembly is adapted to provide a
responsive heat
distribution to a fluid within the housing. The heat distribution is
"responsive" based on
the implementation of the virtual sensing as described herein.
[0008] In another form of the present disclosure, a heater system
comprises a
heater assembly comprising a plurality of heater units, at least one heater
unit defining at
least one independently controlled heating zone. A plurality of power
conductors are
electrically connected to the heater units, and a power supply device includes
a controller
configured to modulate power to the at least one independently controlled
heating zone
through the power conductors. The controller is configured to calculate
temperature
within the at least one heater unit based on a predefined model and at least
one input,
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Date Recue/Date Received 2022-03-09
and the controller modulates power to the at least one heater unit based on
the calculated
temperature.
[0009] In variations of this heater system, which may be implemented
individually
or in any combination: the at least one heater unit is an end heater unit; the
controller
calculates temperature by supplying a known current to the plurality of heater
units,
measuring a voltage of the at least one independently controlled heating zone,
and
comparing the measured voltage to a nominal voltage associated with the known
current
to identify voltage deviations and/or corresponding resistance deviations; and
the
controller calculates temperature by supplying a known voltage to the
plurality of heater
units, measuring a current of the at least one independently controlled
heating zone, and
comparing the measured current to a nominal current associated with the known
voltage
to identify current deviations and/or corresponding resistance deviations.
Further still, an
apparatus having these variations of the heater system includes a sealed
housing
defining an internal chamber and having a fluid inlet and a fluid outlet. The
heater
assembly is disposed within the internal chamber of the housing and is adapted
to provide
a responsive heat distribution to a fluid within the housing.
[0010] In yet another form, a heater system includes a heater assembly
comprising
a plurality of heater units, more than one of the plurality of heater units
defining at least
one independently controlled heating zone. A plurality of power conductors are
electrically connected to the heater units, and a power supply device includes
a controller
configured to modulate power to the independently controlled heating zones
through the
power conductors. The controller is configured to calculate temperature within
the at
more than one heater units based on a predefined model and at least one input,
and the
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Date Recue/Date Received 2022-03-09
controller modulates power to the more than one heater units based on the
calculated
temperature.
[0011] In variations of this heater system, which may be implemented
individually
or in any combination: the at least one heater unit is an end heater unit; the
controller
calculates temperature by supplying a known current to the plurality of heater
units,
measuring a voltage of the at least one independently controlled heating zone,
and
comparing the measured voltage to a nominal voltage associated with the known
current
to identify voltage deviations and/or corresponding resistance deviations; and
the
controller calculates temperature by supplying a known voltage to the
plurality of heater
units, measuring a current of the at least one independently controlled
heating zone, and
comparing the measured current to a nominal current associated with the known
voltage
to identify current deviations and/or corresponding resistance deviations.
[0012] Further areas of applicability will become apparent from the
description
provided herein. It should be understood that the description and specific
examples are
intended for purposes of illustration only and are not intended to limit the
scope of the
present disclosure.
DRAWINGS
[0013] In order that the disclosure may be well understood, there will
now be
described various forms thereof, given by way of example, reference being made
to the
accompanying drawings, in which:
[0014] FIG. 1 is a perspective view of a heater bundle constructed in
accordance
with the teachings of the present disclosure;
Date Recue/Date Received 2022-03-09
[0015] FIG. 2 is a perspective view of a heater assembly of the heater
bundle of
FIG. 1 in accordance with the teachings of the present disclosure;
[0016] FIG. 3 is a perspective view of a variant of a heater assembly of
the heater
bundle of FIG. 1 in accordance with the teachings of the present disclosure;
[0017] FIG. 4 is a perspective view of the heater assembly of FIG. 3 in
accordance
with the teachings of the present disclosure, wherein the outer sheath of the
heater
assembly is removed for clarity;
[0018] FIG. 5 is a perspective view of a core body of the heater assembly
of FIG.
3 in accordance with the teachings of the present disclosure;
[0019] FIG. 6 is a perspective view of a heat exchanger including the
heater bundle
of FIG. 1 in accordance with the teachings of the present disclosure, wherein
the heater
bundle is partially disassembled from the heat exchanger to expose the heater
bundle for
illustration purposes;
[0020] FIG. 7 is a block diagram of a method of operating a heater system
including
a heater bundle constructed in accordance with the teachings of the present
disclosure;
[0021] FIG. 8 is a perspective view of the heater assembly including a
thermal
provision in accordance with the teachings of the present disclosure;
[0022] FIG. 9 is a cross-sectional view of the heater assembly along line
9-9 of
FIG. 8 in accordance with the teachings of the present disclosure;
[0023] FIG. 10 is a cross-sectional view of the heater assembly along
line 10-10 of
FIG. 8 in accordance with the teachings of the present disclosure;
[0024] FIG. 11 is a perspective view of the heater assembly including
another
thermal provision in accordance with the teachings of the present disclosure;
6
Date Recue/Date Received 2022-03-09
[0025] FIG. 12 is a cross-sectional view of the heater assembly along
line 12-12 of
FIG. 11 in accordance with the teachings of the present disclosure;
[0026] FIG. 13 is a cross-sectional view of the heater assembly along
line 13-13 of
FIG. 11 in accordance with the teachings of the present disclosure;
[0027] FIG. 14 is a perspective view of the heater assembly including
another
thermal provision in accordance with the teachings of the present disclosure;
[0028] FIG. 15 is a side view of the thermal provision of the heater
assembly of
FIG. 14 in accordance with the teachings of the present disclosure;
[0029] FIG. 16 is a perspective view of the heater assembly including a
thermal
provision in accordance with the teachings of the present disclosure;
[0030] FIG. 17 is a perspective view of the heater assembly including a
thermal
provision in accordance with the teachings of the present disclosure;
[0031] FIG. 18 is a cross-sectional view of the heater assembly along
line 18-18 of
FIG. 17 in accordance with the teachings of the present disclosure;
[0032] FIG. 19 is a cross-sectional view of the heater assembly along
line 19-19 of
FIG. 17 in accordance with the teachings of the present disclosure; and
[0033] FIG. 20 is a perspective view of the heater assembly including a
thermal
provision in accordance with the teachings of the present disclosure.
[0034] The drawings described herein are for illustration purposes only
and are not
intended to limit the scope of the present disclosure in any way.
DETAILED DESCRIPTION
[0035] The following description is merely exemplary in nature and is not
intended
to limit the present disclosure, application, or uses.
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Date Recue/Date Received 2022-03-09
[0036] Referring to FIG. 1, a heater system constructed in accordance
with the
teachings of the present disclosure is generally indicated by reference
numeral 10. The
heater system 10 includes a heater bundle 12 and a power supply device 14
electrically
connected to the heater bundle 12. The power supply device 14 includes a
controller 15
for controlling power supply to the heater bundle 12. A "heater bundle", as
used in the
present disclosure, refers to a heater apparatus including two or more
physically distinct
heating devices that can be independently controlled. Therefore, when one of
the heating
devices in the heater bundle fails or degrades, the remaining heating devices
in the heater
bundle 12 can continue to operate.
[0037] In one form, the heater bundle 12 includes a mounting flange 16
and a
plurality of heater assemblies 18 secured to the mounting flange 16. The
mounting flange
16 includes a plurality of apertures 20 through which the heater assemblies 18
extend.
Although the heater assemblies 18 are arranged to be parallel in this form, it
should be
understood that alternate positions/arrangements of the heater assemblies 18
are within
the scope of the present disclosure.
[0038] As further shown, the mounting flange 16 includes a plurality of
mounting
holes 22. By using screws or bolts (not shown) through the mounting holes 22,
the
mounting flange 16 may be assembled to a wall of a vessel or a pipe (not
shown) that
carries a fluid to be heated. At least a portion of the heater assemblies 18
are be
immersed in the fluid inside the vessel or pipe to heat the fluid in this form
of the present
disclosure.
[0039] Referring to FIG. 2, the heater assemblies 18 according to one
form may
be in the form of a cartridge heater 30. The cartridge heater 30 is a tube-
shaped heater
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Date Recue/Date Received 2022-03-09
that generally includes a core body 32, a resistive heating wire 34 wrapped
around the
core body 32, a metal sheath 36 enclosing the core body 32 and the resistive
heating
wire 34 therein, and an insulating material 38 filling in the space in the
metal sheath 36 to
electrically insulate the resistive heating wire 34 from the metal sheath 36
and to thermally
conduct the heat from the resistive heating wire 34 to the metal sheath 36.
The core body
32 may be made of ceramic. The insulation material 38 may be compacted
Magnesium
Oxide (MgO). A plurality of power conductors 42 extend through the core body
32 along
a longitudinal direction and are electrically connected to the resistive
heating wires 34.
The power conductors 42 also extend through an end piece 44 that seals the
metal sheath
36. The power conductors 42 are connected to the power supply device 14 (shown
in
FIG. 1) to supply power from the power supply device 14 to the resistive
heating wire 34.
While FIG. 2 shows only two power conductors 42 extending through the end
piece 44,
more than two power conductors 42 can extend through the end piece 44. The
power
conductors 42 may be in the form of conductive pins. Various constructions and
further
structural and electrical details of cartridge heaters are set forth in
greater detail in U.S.
Patent Nos. 2,831,951 and 3,970,822, which are commonly assigned with the
present
application. Therefore, it should be understood that the form illustrated
herein is merely
exemplary and should not be construed as limiting the scope of the present
disclosure.
[0040]
Alternatively, multiple resistive heating wires 34 and multiple pairs of power
conductors 42 may be used to form multiple heating circuits that can be
independently
controlled to enhance reliability of the cartridge heater 30. Therefore, when
one of the
resistive heating wires 34 fails, the remaining resistive heating wires 34 may
continue to
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Date Recue/Date Received 2022-03-09
generate heat without causing the entire cartridge heater 30 to fail and
without causing
costly machine downtime.
[0041] Referring to FIGS. 3 to 5, the heater assemblies 50 may be in the
form of a
cartridge heater having a configuration similar to that of FIG. 2 except for
the number of
core bodies and number of power conductors used. More specifically, the heater
assemblies 50 each include a plurality of heater units 52, and an outer metal
sheath 54
enclosing the plurality of heater units 52 therein, along with a plurality of
power conductors
56. An insulating material (not shown in FIGS. 3 to 5) is provided between the
plurality
of heater units 52 and the outer metal sheath 54 to electrically insulate the
heater units
52 from the outer metal sheath 54. The plurality of heater units 52 each
include a core
body 58 and a resistive heating element 60 surrounding the core body 58. The
resistive
heating element 60 of each heater unit 52 may define one or more heating
circuits to
define one or more heating zones 62.
[0042] In the present form, each heater unit 52 defines one heating zone
62 and
the plurality of heater units 52 in each heater assembly 50 are aligned along
a longitudinal
direction X. Therefore, each heater assembly 50 defines a plurality of heating
zones 62
aligned along the longitudinal direction X. The core body 58 of each heater
unit 52
defines a plurality of through holes/apertures 64 to allow power conductors 56
to extend
therethrough. The resistive heating elements 60 of the heater units 52 are
connected to
the power conductors 56, which, in turn, are connected to the power supply
device 14.
The power conductors 56 supply the power from the power supply device 14 to
the
plurality of heater units 52. By properly connecting the power conductors 56
to the
resistive heating elements 60, the resistive heating elements 60 of the
plurality of heater
Date Recue/Date Received 2022-03-09
units 52 can be independently controlled by the controller 15 of the power
supply device
14. As such, failure of one resistive heating element 60 for a particular
heating zone 62
will not affect the proper functioning of the remaining resistive heating
elements 60 for the
remaining heating zones 62. Further, the heater units 52 and the heater
assemblies 50
may be interchangeable for ease of repair or assembly.
[0043] In the present form, six power conductors 56 are used for each
heater
assembly 50 to supply power to five independent electrical heating circuits on
the five
heater units 52. Alternatively, six power conductors 56 may be connected to
the resistive
heating elements 60 in a way to define three fully independent circuits on the
five heater
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 zones
62. For example, seven power conductors 56 may be used to provide six heating
zones
62. Eight power conductors 56 may be used to provide seven heating zones 62.
[0044] The power conductors 56 may include a plurality of power supply
and power
return conductors, a plurality of power return conductors and a single power
supply
conductor, or a plurality of power supply conductors and a single power return
conductor.
If the number of heater zones is n, the number of power supply and return
conductors is
n +1.
[0045] Alternatively, a higher number of electrically distinct heating
zones 62 may
be created through multiplexing, polarity sensitive switching and other
circuit topologies
by the controller 15 of the power supply device 14. Use of multiplexing or
various
arrangements of thermal arrays 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
11
Date Recue/Date Received 2022-03-09
six power conductors for 15 or 30 zones.) is disclosed in U.S. Patent Nos.
9,123,755,
9,123,756, 9,177,840, 9,196,513, and their related applications, which are
commonly
assigned with the present application.
[0046] With this structure, each heater assembly 50 includes a plurality
of heating
zones 62 that can be independently controlled to vary the power output or heat
distribution
along the length of the heater assembly 50. The heater bundle 12 includes a
plurality of
such heater assemblies 50. Therefore, the heater bundle 12 provides a
plurality of
heating zones 62 and a tailored heat distribution for heating the fluid that
flows through
the heater bundle 12 to be adapted for specific applications. The power supply
device 14
can be configured to modulate power to each of the independently controlled
heating
zones 62.
[0047] For example, a heater assembly 50 may define "m" heating zones,
and the
heater bundle may include "k" heating assemblies 50. Therefore, the heater
bundle 12
may define mxk heating zones. The plurality of heating zones 62 in the heater
bundle 12
can be individually and dynamically controlled in response to heating
conditions and/or
heating requirements, including but not limited to, the life and the
reliability of the
individual heater units 52, the sizes and costs of the heater units 52, local
heater flux,
characteristics and operation of the heater units 52, and the entire power
output.
[0048] Each circuit is individually controlled at a desired temperature
or a desired
power level so that the distribution of temperature and/or power adapts to
variations in
system parameters (e.g. manufacturing variation/tolerances, changing
environmental
conditions, changing inlet flow conditions such as inlet temperature, inlet
temperature
distribution, flow velocity, velocity distribution, fluid composition, fluid
heat capacity, etc.).
12
Date Recue/Date Received 2022-03-09
More specifically, the heater units 52 may not generate the same heat output
when
operated under the same power level due to manufacturing variations as well as
varied
degrees of heater degradation over time. The heater units 52 may be
independently
controlled to adjust the heat output according to a desired heat distribution.
The individual
manufacturing tolerances of components of the heater system and assembly
tolerances
of the heater system are increased as a function of the modulated power of the
power
supply, or in other words, because of the high fidelity of heater control,
manufacturing
tolerance of individual components need not be as tight/narrow.
[0049] The heater units 52 may each include a temperature sensor (not
shown) for
measuring the temperature of the heater units 52. When a hot spot in the
heater units 52
is detected, the power supply device 14 may reduce or turn off the power to
the particular
heater unit 52 on which the hot spot is detected to avoid overheating or
failure of the
particular heater unit 52. The power supply device 14 may modulate the power
to the
heater units 52 adjacent to the disabled heater unit 52 to compensate for the
reduced
heat output from the particular heater unit 52.
[0050] The power supply device 14 may include multi-zone algorithms to
turn off
or turn down the power level delivered to any particular zone, and to increase
the power
to the heating zones adjacent to the particular heating zone that is disabled
and has a
reduced heat output. By carefully modulating the power to each heating zone,
the overall
reliability of the system can be improved. By detecting the hot spot and
controlling the
power supply accordingly, the heater system 10 has improved safety.
[0051] The heater bundle 12 with the multiple independently controlled
heating
zones 62 can accomplish improved heating. For example, some circuits on the
heater
13
Date Recue/Date Received 2022-03-09
units 52 may be operated at a nominal (or "typical") duty cycle of less than
100% (or at
an average power level that is a fraction of the power that would be produced
by the
heater with line voltage applied). The lower duty cycles allow for the use of
resistive
heating wires with a larger diameter, thereby improving reliability.
[0052] Normally, smaller zones would employ a finer wire size to achieve
a given
resistance. Variable power control allows a larger wire size to be used, and a
lower
resistance value can be accommodated, while protecting the heater from over-
loading
with a duty cycle limit tied to the power dissipation capacity of the heater.
[0053] The use of a scaling factor may be tied to the capacity of the
heater units
52 or the heating zone 62. The multiple heating zones 62 allow for more
accurate
determination and control of the heater bundle 12. The use of a specific
scaling factor for
a particular heating circuit/zone will allow for a more aggressive (i.e.
higher) temperature
(or power level) at almost all zones, which, in turn, lead to a smaller, less
costly design
for the heater bundle 12. Such a scaling factor and method is disclosed in
U.S. Patent
No. 7,257,464, which is commonly assigned with the present application.
[0054] The sizes of the heating zones controlled by the individual
circuits can be
made equal or different to reduce the total number of zones needed to control
the
distribution of temperature or power to a desired accuracy.
[0055] Referring back to FIG. 1, the heater assemblies 18 are shown to be
a single
end heater, i.e., the conductive pin extends through only one longitudinal end
of the
heater assemblies 18. The heater assembly 18 may extend through the mounting
flange
16 or a bulkhead (not shown) and sealed to the flange 16 or bulkhead. As such,
the
14
Date Recue/Date Received 2022-03-09
heater assemblies 18 can be individually removed and replaced without removing
the
mounting flange 16 from the vessel or tube.
[0056]
Alternatively, the heater assembly 18 may be a "double ended" heater. In
a double-ended heater, the metal sheath is bent into a hairpin shape and the
power
conductors pass through both longitudinal ends of the metal sheath so that
both
longitudinal ends of the metal sheath pass through and are sealed to the
flange or
bulkhead. In this structure, the flange or the bulkhead need to be removed
from the
housing or the vessel before the individual heater assembly 18 can be
replaced.
[0057]
Referring to FIG. 6, a heater bundle 12 is incorporated in a heat exchanger
70. The heat exchanger 70 includes a sealed housing 72 defining an internal
chamber
(not shown), a heater bundle 12 disposed within the internal chamber of the
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 internal chamber of the sealed housing 72. The
fluid is heated
by the heater bundle 12 disposed in the sealed housing 72. The heater bundle
12 may
be arranged for either cross-flow or for flow parallel to their length.
[0058]
The heater bundle 12 is connected to the power supply device 14 which
may include a means to modulate power, such as a switching means or a variable
transformer, to modulate the power supplied to an individual zone. The power
modulation
may be performed as a function of time or based on detected temperature of
each heating
zone.
[0059]
The resistive heating wire may also function as a sensor using the
resistance of the resistive wire to measure the temperature of the resistive
wire and using
the same power conductors to send temperature measurement information to the
power
Date Recue/Date Received 2022-03-09
supply device 14. A means of sensing temperature for each zone would allow the
control
of temperature along the length of each heater assembly 18 in the heater
bundle 12 (down
to the resolution of the individual zone). Therefore, the additional
temperature sensing
circuits and sensing means can be dispensed with, thereby reducing the
manufacturing
costs. Direct measurement of the heater circuit temperature is a distinct
advantage when
trying to maximize heat flux in a given circuit while maintaining a desired
reliability level
for the system because it eliminates or minimizes many of the measurement
errors
associated with using a separate sensor. The heating element temperature is
the
characteristic that has the strongest influence on heater reliability. Using a
resistive
element to function as both a heater and a sensor is disclosed in U.S. Patent
No.
7,196,295, which is commonly assigned with the present application.
[0060] Alternatively, the power conductors 56 may be made of dissimilar
metals
such that the power conductors 56 of dissimilar metals may create a
thermocouple for
measuring the temperature of the resistive heating elements. For example, at
least one
set of a power supply and a power return conductor may include different
materials such
that a junction is formed between the different materials and a resistive
heating element
of a heater unit and is used to determine temperature of one or more zones.
Use of
"integrated" and "highly thermally coupled" sensing, such as using different
metals for the
heater leads to generation of a thermocouple-like signal. The use of the
integrated and
coupled power conductors for temperature measurement is disclosed in U.S.
Application
No. 14/725,537, which is commonly assigned with the present application.
[0061] The controller 15 for modulating the electrical power delivered to
each zone
may be a closed-loop automatic control system. The closed-loop automatic
control
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Date Recue/Date Received 2022-03-09
system receives the temperature feedback from each zone and automatically and
dynamically controls the delivery of power to each zone, thereby automatically
and
dynamically controlling the power distribution and temperature along the
length of each
heater assembly 18 in the heater bundle 12 without continuous or frequent
human
monitoring and adjustment.
[0062] The heater units 52 as disclosed herein may also be calibrated
using a
variety of methods including, but not limited to, energizing and sampling each
heater unit
52 to calculate its resistance. The calculated resistance can then be compared
to a
calibrated resistance to determine a resistance ratio, or a value to then
determine actual
heater unit temperatures. Exemplary methods are disclosed in U.S. Patent Nos.
5,280,422 and 5,552,998, which are commonly assigned with the present
application.
[0063] One form of calibration includes operating the heater system 10 in
at least
one mode of operation, controlling the heater system 10 to generate a desired
temperature for at least one of the independently controlled heating zones 62,
collecting
and recording data for the at least one independently controlled heating zones
62 for the
mode of operation, then accessing the recorded data to determine operating
specifications for a heating system having a reduced number of independently
controlled
heating zones, and then using the heating system with the reduced number of
independently controlled heating zones. The data may include, by way of
example, power
levels and/or temperature information, among other operational data from the
heater
system 10 having its data collected and recorded.
[0064] In a variation of the present disclosure, the heater system may
include a
single heater assembly 18, rather than a plurality of heater assemblies in a
heater bundle
17
Date Recue/Date Received 2022-03-09
12. The single heater assembly 18 would comprise a plurality of heater units
52, each
heater unit 52 defining at least one independently controlled heating zone.
Similarly,
power conductors 56 are electrically connected to each of the independently
controlled
heating zones 62 in each of the heater units 52, and the power supply device
is configured
to modulate power to each of the independently controlled heating zones 62 of
the heater
units through the power conductors 56.
[0065] Referring to FIG. 7, a method 100 of controlling a heater system
includes
providing a heater bundle comprising a plurality of heater assemblies in step
102. Each
heater assembly includes a plurality of heater units. Each heater unit defines
at least one
independently controlled heating circuit (and consequently heating zone). The
power to
each of the heater units is supplied through power conductors electrically
connected to
each of the independently controlled heating zones in each of the heater units
in step
104. The temperature within each of the zones is detected in step 106. The
temperature
may be determined using a change in resistance of a resistive heating element
of at least
one of the heater units. The zone temperature may be initially determined by
measuring
the zone resistance (or, by measurement of circuit voltage, if appropriate
materials are
used).
[0066] The temperature values may be digitalized. The signals may be
communicated to a microprocessor. The measured (detected) temperature values
may
be compared to a target (desired) temperature for each zone in step 108. The
power
supplied to each of the heater units may be modulated based on the measured
temperature to achieve the target temperatures in step 110.
18
Date Recue/Date Received 2022-03-09
[0067] Optionally, the method may further include using a scaling factor
to adjust
the modulating power. The scaling factor may be a function of a heating
capacity of each
heating zone. The controller 15 may include an algorithm, potentially
including a scaling
factor and/or a mathematical model of the dynamic behavior of the system
(including
knowledge of the update time of the system), to determine the amount of power
to be
provided (via duty cycle, phase angle firing, voltage modulation or similar
techniques) to
each zone until the next update. The desired power may be converted to a
signal, which
is sent to a switch or other power modulating device for controlling power
output to the
individual heating zones.
[0068] In the present form, when at least one heating zone is turned off
due to an
anomalous condition, the remaining zones continue to provide a desired wattage
without
failure. Power is modulated to a functional heating zone to provide a desired
wattage
when an anomalous condition is detected in 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 a desired wattage. The power is modulated to each of the
heating
zones as a function of at least one of received signals, a model, and as a
function of time.
[0069] For safety or process control reasons, typical heaters are
generally
operated to be below a maximum allowable temperature in order to prevent a
particular
location of the heater from exceeding a given temperature due to unwanted
chemical or
physical reactions at the particular location, such as
combustion/fire/oxidation, coking
boiling etc.). Therefore, this is normally accommodated by a conservative
heater design
(e.g., large heaters with low power density and much of their surface area
loaded with a
much lower heat flux than might otherwise be possible).
19
Date Recue/Date Received 2022-03-09
[0070] However, with the heater bundle of the present disclosure, it is
possible to
measure and limit the temperature of any location within the heater down to a
resolution
on the order of the size of the individual heating zones. A hot spot large
enough to
influence the temperature of an individual circuit can be detected.
[0071] Since the temperature of the individual heating zones can be
automatically
adjusted and consequently limited, the dynamic and automatic limitation of
temperature
in each zone will maintain this zone and all other zones to be operating at an
optimum
power/heat flux level without fear of exceeding the desired temperature limit
in any zone.
This brings an advantage in high-limit temperature measurement accuracy over
the
current practice of clamping a separate thermocouple to the sheath of one of
the elements
in a bundle. The reduced margin and the ability to modulate the power to
individual zones
can be selectively applied to the heating zones, selectively and individually,
rather than
applied to an entire heater assembly, thereby reducing the risk of exceeding a
predetermined temperature limit.
[0072] The characteristics of the cartridge heater may vary with time.
This time
varying characteristic would otherwise require that the cartridge heater be
designed for a
single selected (worse-case) flow regime and therefore, the cartridge heater
would
operate at a sub-optimum state for other states of flow.
[0073] However, with dynamic control of the power distribution over the
entire
bundle down to a resolution of the core size due to the multiple heating units
provided in
the heater assembly, an optimized power distribution for various states of
flow can be
achieved, as opposed to only one power distribution corresponding to only one
flow state
Date Recue/Date Received 2022-03-09
in the typical cartridge heater. Therefore, the heater bundle of the present
application
allows for an increase in the total heat flux for all other states of flow.
[0074] Further, variable power control can increase heater design
flexibility. The
voltage can be de-coupled from resistance (to a great degree) in heater design
and the
heaters may be designed with the maximum wire diameter that can be fitted into
the
heater. It allows for increased capacity for power dissipation for a given
heater size and
level of reliability (or life of the heater) and allows for the size of the
bundle to be
decreased for a given overall power level. Power in this arrangement can be
modulated
by a variable duty cycle that is a part of the variable wattage controllers
currently available
or under development. The heater bundle can be protected by a programmable (or
pre-
programmed if desired) limit to the duty cycle for a given zone to prevent
"overloading"
the heater bundle.
[0075] With reference to FIG. 8, a perspective view of the heater
assembly 50 with
a thermal provision is shown. Generally, the thermal provision is configured
to modify a
thermal conductance along a length of the at least one heater assembly to
compensate
for non-uniform temperatures within at least one heater unit. This thermal
provision may
take on a variety of forms as set forth in greater detail below.
[0076] As described above, the heater assemblies 50 each include a
plurality of
heater units 52. Each heater unit 52 defines one of an end heater unit 52-1
and adjacent
heater units 52-2. As shown in FIGS. 9-10, each of the end heater units 52-1
and the
adjacent heater units 52-2 include a core body 58 and a resistive heating
element 60
surrounding the core body 58. The resistive heating element 60 of each end
heater unit
21
Date Recue/Date Received 2022-03-09
52-1 defines one or more end heating zones 62-1, and the resistive heating
element 60
of each adjacent heater unit 52-2 defines one or more adjacent heating zones
62-2.
[0077] The resistive heating elements 60 of the end heater units 52-1 and
the
adjacent heater units 52-2 are connected to the power conductors 56, which, in
turn, are
connected to the power supply device 14. The power conductors 56 supply the
power
from the power supply device 14 to the end heater units 52-1 and the adjacent
heater
units 52-2. By selectively connecting the power conductors 56 to the resistive
heating
elements 60, the resistive heating elements 60 of the end heater units 52-1
and the
adjacent heater units 52-2 can be independently controlled by the controller
15 of the
power supply device 14.
[0078] In one form, the thermal provision of the heater assembly 50 is
implemented
by a conductive sleeve 120. As an example, and with reference to FIG. 10, the
conductive
sleeve 120 is disposed proximate to the resistive heating element 60 of the
end heater
unit 52-1. In one form, the conductive sleeve 120 surrounds the resistive
heating element
60 and the core body 58, and the conductive sleeve 120 is disposed between the
outer
metal sheath 54 and the resistive heating element 60. It should be understood
that the
conductive sleeve 120 may not entirely surround the resistive heating element
60 and the
core body 58 in other forms. It should also be understood that the conductive
sleeve 120
may not be disposed between the outer metal sheath 54 and the resistive
heating element
60 in other forms.
[0079] In one form, the conductive sleeve 120 has a thermal conductivity
that is
greater than a thermal conductivity of the outer metal sheath 54. Accordingly,
the
conductive sleeve 120 is configured to increase the conductance of the end
heater unit
22
Date Recue/Date Received 2022-03-09
52-1 relative to the adjacent heater units 52-2 and thereby inhibit
undesirable temperature
gradients along the heater assembly 50.
[0080] With reference to FIG. 11, a perspective view of the heater
assembly 50
with another example thermal provision is shown. In one form, the thermal
provision of
the heater assembly 50 is implemented by outer sheath thermal provision 130.
More
particularly and with reference to FIGS. 12-13, the heater assembly 50
includes end outer
metal sheaths 54-1 and adjacent outer metal sheaths 54-2, respectively. The
end outer
metal sheaths 54-1 and the adjacent outer metal sheaths 54-2 collectively form
the outer
metal sheath 54, and the outer sheath thermal provision 130 is implemented by
the end
outer end metal sheaths 54-2.
[0081] In one form, the end outer metal sheaths 54-1 and the adjacent
outer metal
sheaths 54-2 have different thicknesses and/or thermal conductivities. As an
example,
the end outer metal sheaths 54-1 have a greater thickness and a higher thermal
conductivity relative to the adjacent outer metal sheaths 54-2. Accordingly,
the end outer
metal sheaths 54-1 are configured to increase the conductance of the end
heater unit 52-
1 relative to the adjacent heater units 52-2 and thereby, inhibit undesirable
temperature
gradients along the heater assembly 50. It should be understood that the end
outer metal
sheaths 54-1 and the adjacent outer metal sheaths 54-2 can have varying
thicknesses
and/or thermal conductivities in other variations to selectively control the
thermal
gradients along the heater assembly 50.
[0082] With reference to FIG. 14, perspective view of the heater assembly
50 with
another example thermal provision is shown. In this form, the thermal
provision of the
heater assembly 50 is implemented by power conductor thermal provision 140.
The
23
Date Recue/Date Received 2022-03-09
power conductor thermal provision 140 is implemented by end power conductors
56-1
and adjacent power conductors 56-2. In one form, the end power conductors 56-1
and
the adjacent power conductors 56-2 collectively form the plurality of power
conductors
56. The end power conductors 56-1 are connected to the resistive heating
elements 60
of the end heater units 52-1, and the adjacent power conductors 56-2 are
connected to
the resistive heating elements 60 of the adjacent heater units 52-2.
[0083] In some forms and with reference to FIGS. 14-15, the end power
conductors
56-1 and the adjacent power conductors 56-2 have different thicknesses, cross-
sectional
areas, and/or thermal conductivities. As an example, the end power conductors
56-1 have
a greater thickness (Ti) and cross-sectional area (which is proportional to
the thickness
Ti in this form) than the thickness (T2) and cross-sectional area of the
adjacent power
conductors 56-2 (which is proportional to the thickness T2 in this form).
Accordingly, the
end power conductors 56-1 are configured to increase the conductance of the
end heater
unit 52-1 relative to the adjacent heater units 52-2 and thereby, inhibit
undesirable
temperature gradients along the heater assembly 50. It should be understood
that the
end power conductors 56-1 and the adjacent power conductors 56-2 can have
varying
thicknesses, cross-sectional areas, and/or thermal conductivities in other
forms to
selectively control the thermal gradients along the heater assembly 50.
[0084] With reference to FIG. 16, a perspective view of the heater
assembly 50
with another example thermal provision is shown. In one form, the heater
assembly 50
includes end spacings 150 and adjacent spacings 152, and the thermal provision
of the
heater assembly 50 is defined by the end spacings 150. As used herein,
"spacing" refers
to a gap between consecutive heater units 52. As an example, the end spacings
150 refer
24
Date Recue/Date Received 2022-03-09
to the gaps between the end heater units 52-1 and an adjacent heater unit 52-
2, and the
adjacent spacings 152 refer to the gaps between adjacent heater units 52-2. In
one form,
a width of the end spacings 150 (WO in the longitudinal direction X is greater
than a width
of the adjacent spacings 152 (W2) in the longitudinal direction X.
[0085] While the width of the end spacings 150 (WO illustrated in FIG. 16
are equal,
it should be understood that the width of the end spacings 150 (WO can be
unequal in
other forms. Likewise, while the width of the adjacent spacings 152 (W2)
illustrated in FIG.
15 are equal, it should be understood that the width of the adjacent spacings
152 (W2)
can be unequal in other forms. In one form, the width of the end spacings 150
(WO is less
than or equal to a width of the adjacent spacings 152 (W2). By selectively
designating the
width of the end spacings 150 (WO and the width of the adjacent spacings 152
(W2), the
conductance of the end heater units 52-1 relative to the adjacent heater units
52-2 can
be increased to inhibit undesirable temperature gradients along the heater
assembly 50.
[0086] With reference to FIG. 17, a perspective view of the heater
assembly 50
with another example thermal provision is shown. In some forms, the heater
assembly 50
includes end spacers 160 and adjacent spacers 162, and the thermal provision
of the
heater assembly 50 is implemented by the end spacers 160. The end spacers 160
are
disposed between the end heater units 52-1 and an adjacent heater unit 52-2,
and the
adjacent spacers 162 are disposed between adjacent heater units 52-2. The end
spacers
160 and the adjacent spacers 162 may be implemented by various materials
having lower
thermal conductivities, such as a ceramic material (e.g., aluminum nitride,
boron nitride,
polyurethane, and a glass-based material, such as borosilicate glass, acrylic
glass,
fiberglass, among others).
Date Recue/Date Received 2022-03-09
[0087] In some forms, a width of the end spacers 160 (W3) in the
longitudinal
direction X is greater than a width of the adjacent spacers 162 (W4) in the
longitudinal
direction X. While the width of the end spacers 160 (W3) illustrated in FIG.
17 are equal,
it should be understood that the width of the end spacers 160 (W3) can be
unequal in
other forms. Likewise, while the width of the adjacent spacers 162 (W4)
illustrated in FIG.
15 are equal, it should be understood that the width of the adjacent spacers
162 (W4) can
be unequal in other forms. In one form, the width of the end spacers 160 (W3)
is less than
or equal to a width of the adjacent spacers 162 (W4). By selectively
designating the width
of the end spacers 160 (W3) and the width of the adjacent spacers 162 (W4),
the
conductance of the end heater units 52-1 relative to the adjacent heater units
52-2 can
be increased to inhibit undesirable temperature gradients along the heater
assembly 50.
[0088] In one form, the power conductor thermal provision 140 described
above
with reference to FIGS. 14-15 and the end spacers 160 are combined to
collectively form
a thermal provision. As an example and as shown in FIGS. 18-19, the end power
conductors 56-1 extend along the heater assembly 50 in the longitudinal
direction X such
that the end power conductors 56-1 are disposed within a corresponding end
spacer 160
and within the corresponding end heater unit 52-1 (not shown). Likewise, the
adjacent
power conductors 56-2 extend along the heater assembly 50 in the longitudinal
direction
X such that the adjacent power conductors 56-2 are disposed within a
corresponding
adjacent spacer 162 and within the corresponding adjacent heater unit 52-2
(not shown).
In some forms, the end power conductors 56-1 disposed within the end spacer
160 have
a greater cross-sectional area than the adjacent power conductors 56-2
disposed within
the adjacent spacers 162. It should be understood that the end power
conductors 56-1
26
Date Recue/Date Received 2022-03-09
disposed within the end spacer 160 may have a cross-sectional area that is
less than or
equal to the cross-sectional area of the adjacent power conductors 56-2
disposed within
the adjacent spacers 162 in other forms.
[0089] With reference to FIG. 20, a perspective view of the heater
assembly 50
with another example thermal provision is shown. In one form, the thermal
provision of
the heater assembly 50 is implemented by variable width thermal provision 170.
The
variable width thermal provision 170 includes at least one of the end heater
units 52-1. In
some forms, a width of the end heater units 52-1 (W5) in the longitudinal
direction X is
greater than a width of the adjacent heater units 52-2 (W6) in the
longitudinal direction X.
It should be understood that the width of the end heater units 52-1 (W5) may
be less than
or equal to the width of the adjacent heater units 52-2 (W6) in other forms.
By selectively
designating the width of the end heater units 52-1 (W5) and the width of the
adjacent
heater units 52-2 (W6), the conductance of the end heater units 52-1 relative
to the
adjacent heater units 52-2 can be increased to inhibit undesirable temperature
gradients
along the heater assembly 50. While not illustrated, it should be readily
understood that
the power conductors for the heater units 52 extend between the end heater
units 52-1
through the adjacent heater units 52-2.
[0090] With reference to FIGS. 8-20, the controller 15 is configured to
calculate a
temperature within at least one of the heater units 52, such as the end heater
unit 52-1,
based on a predefined model (e.g., a mathematical model representing various
components and/or dynamic behaviors of the heater system 10, among others) and
at
least one input. (This general approach can also be referred to as "virtual
sensing" since
temperature is calculated rather than measured). In one form, the at least one
input
27
Date Recue/Date Received 2022-03-09
includes, but is not limited to, a temperature at another location within the
heater bundle
12, a temperature of another heater unit 52, a temperature of any one of the
independently controlled heating zones 62 located on the heater assembly 18, a
power
consumption of the heater bundle 12 and/or any one of the heater units 52,
and/or an
average power consumption over a predetermined time period of the heater
bundle 12
and/or any one of the heater units 52. In one form, the at least one input
includes, but is
not limited to, a voltage of the heater bundle 12 and/or any one of the heater
units 52, a
current of the heater bundle 12 and/or any one of the heater units 52, a
current leakage
of the heater bundle 12 and/or any one of the heater units 52, and/or an
insulation
resistance of the heater bundle 12. To perform the functionality described
herein, the
controller 15 includes one or more electrical circuits/components for
obtaining the at least
one input (e.g., one or more sensing circuits for measuring power of the
heater units 52).
[0091]
As an example, the controller 15 is configured to calculate a temperature
within the end heater unit 52-1 by initially supplying a known current to the
heater units
52 and measuring the voltage of the end heater unit 52-1. The controller 15
then
compares the measured voltage to a nominal voltage associated with the known
current
to identify voltage deviations and/or corresponding resistance deviations.
Subsequently,
the controller 15 calculates, using the predefined model, the temperature of
the end
heater unit 52-1 based on the voltage deviations and/or corresponding
resistance
deviations. As described above, the controller 15 then modulates power to the
independently controlled heating zones 62 through the power conductors 56
based on
the temperature of the end heater unit 52-1. To perform the functionality
described herein,
the controller 15 includes one or more processors configured to execute
instructions
28
Date Recue/Date Received 2022-03-09
stored in a nontransitory computer-readable medium, such as a random-access
memory
(RAM) and/or a read-only memory (ROM). Alternatively, the controller 15
calculates
temperature by supplying a known voltage to the plurality of heater units 52,
measuring
a current of at least one independently controlled heating zone 62, and
comparing the
measured current to a nominal current associated with the known voltage to
identify
current deviations and/or corresponding resistance deviations.
[0092] Unless otherwise expressly indicated herein, all numerical values
indicating
mechanical/thermal properties, compositional percentages, dimensions and/or
tolerances, or other characteristics are to be understood as modified by the
word "about"
or "approximately" in describing the scope of the present disclosure. This
modification is
desired for various reasons including industrial practice, material,
manufacturing, and
assembly tolerances, and testing capability.
[0093] Spatial and functional relationships between elements are
described using
various terms, including "connected," "engaged," "coupled," "adjacent," "next
to," on top
of," "above," "below," and "disposed." Unless explicitly being described as
being "direct,"
when a relationship between first and second elements is described in the
present
disclosure, that relationship can be a direct relationship where no other
intervening
elements are present between the first and second elements, and can also be an
indirect
relationship where one or more intervening elements are present (either
spatially or
functionally) between the first and second elements. As used herein, the
phrase at least
one of A, B, and C should be construed to mean a logical (A OR B OR C), using
a non-
exclusive logical OR, and should not be construed to mean at least one of A,
at least one
of B, and at least one of C."
29
Date Recue/Date Received 2022-03-09
[0094]
The description of the disclosure is merely exemplary in nature and, thus,
variations that do not depart from the substance of the disclosure are
intended to be within
the scope of the disclosure. Such variations are not to be regarded as a
departure from
the spirit and scope of the disclosure. Furthermore, various omissions,
substitutions,
combinations, and changes in the forms of the systems, apparatuses, and
methods
described herein may be made without departing from the spirit and scope of
the
disclosure even if said omissions, substitutions, combinations, and changes
are not
explicitly described or illustrated in the figures of the disclosure.
Date Recue/Date Received 2022-03-09
