U.S. patent application number 10/229594 was filed with the patent office on 2004-03-04 for apparatus and method for recovery and recycle of optical fiber coolant gas.
Invention is credited to Lu, Yaping, Micke, Andre, Shedletsky, Igor.
Application Number | 20040040320 10/229594 |
Document ID | / |
Family ID | 31495356 |
Filed Date | 2004-03-04 |
United States Patent
Application |
20040040320 |
Kind Code |
A1 |
Shedletsky, Igor ; et
al. |
March 4, 2004 |
Apparatus and method for recovery and recycle of optical fiber
coolant gas
Abstract
An apparatus and method for recovering and recycling a coolant
gas from a heat exchanger. The apparatus comprises a coolant gas
recovery section, and analysis section, and a coolant gas blending
section. The coolant gas recovery section recovers a coolant gas
containing contaminants from the heat exchanger. The analysis
section monitors a condition of an analysis portion of the
recovered coolant gas. The coolant gas blending section operates to
produce, based on the condition of the recovered coolant gas
monitored by the analysis section, a blend coolant gas comprising a
virgin coolant gas and a reclaimed coolant gas that comprises at
least a portion of the recovered coolant gas. The blend coolant gas
has a predetermined contaminant concentration and is recycled into
the heat exchanger. Thus, the coolant gas is recovered from, and
recycled to, the heat exchanger at the predetermined contaminant
concentration without using a purification device.
Inventors: |
Shedletsky, Igor; (Staten
Island, NY) ; Micke, Andre; (Summit, NJ) ; Lu,
Yaping; (Scotch Plains, NJ) |
Correspondence
Address: |
Philip H. Von Neida
The BOC Group, Inc.
Intellectual Property Dept.
100 Mountain Ave.
Murray Hill
NJ
07974
US
|
Family ID: |
31495356 |
Appl. No.: |
10/229594 |
Filed: |
August 28, 2002 |
Current U.S.
Class: |
62/149 ; 62/292;
62/475 |
Current CPC
Class: |
C03B 2205/57 20130101;
C03B 37/02718 20130101 |
Class at
Publication: |
062/149 ;
062/475; 062/292 |
International
Class: |
F25B 045/00; F25B
043/04 |
Claims
What is claimed is:
1. A method of recovering and recycling a coolant gas containing
contaminants, the method comprising: providing a heat exchanger and
an analyzer, the heat exchanger and the analyzer in operational
association; recovering the coolant gas containing contaminants
from the heat exchanger; delivering an analysis portion of the
recovered coolant gas to the analyzer; analyzing the analysis
portion of the recovered coolant gas with the analyzer to determine
a condition of the recovered coolant gas; blending, based on the
condition, a reclaimed portion of the recovered coolant gas and a
virgin coolant gas to produce a gaseous coolant blend having a
predetermined contaminant concentration; and introducing the
gaseous coolant blend into the heat exchanger such that at least a
portion of the recovered coolant gas is recycled.
2. The method of claim 1, wherein the method further comprises a
step of introducing the virgin coolant gas into the heat exchanger
prior to the recovering step.
3. The method of claim 1, wherein the recovering step and the
delivering step are performed by a single pump.
4. The method of claim 1, wherein the method further comprises
providing the analysis portion of the recovered coolant gas to a
seal associated with the heat exchanger.
5. The method of claim 1, wherein the method further comprises
providing a seal for the heat exchanger using the recovered coolant
gas.
6. The method of claim 1, wherein the method further comprises
providing a control system, the control system associated with the
analyzer and operable to control the blending.
7. The method of claim 1, wherein the analysis portion of the
recovered coolant gas passes through the analyzer at a constant
rate of flow.
8. The method of claim 1, wherein the gaseous coolant blend is
introduced into the heat exchanger at a constant rate of flow.
9. The method of claim 1, wherein the method further comprises
providing means for controlling an amount of contaminants
introduced into the heat exchanger.
10. The method of claim 1, wherein the method further comprises
providing means for controlling a contaminant concentration in the
gaseous coolant blend.
11. The method of claim 1, wherein the method further comprises
providing means for controlling a contaminant concentration in the
gaseous coolant blend introduced into the heat exchanger.
12. The method of claim 1, wherein the method further comprises
dividing the recovered coolant gas into a portion of the recovered
coolant gas that includes the analysis portion of the recovered
coolant gas and the reclaimed portion of the recovered coolant
gas.
13. The method of claim 1, wherein the predetermined contaminant
concentration of the gaseous coolant blend is user defined.
14. The method of claim 1, wherein the method further comprises
maintaining a flow of a portion of the recovered coolant gas
through a by-pass section.
15. The method of claim 14, wherein the method further comprises
simultaneously decreasing the flow of the portion of the recovered
coolant gas through the by-pass section and increasing the flow of
the reclaimed coolant gas through the blending section.
16. The method of claim 14, wherein the maintaining the flow of the
portion of the recovered coolant gas through the by-pass section
reduces lag time.
17. A method of recovering and recycling a coolant gas containing
contaminants, the method comprising: providing a heat exchanger and
an analyzer, the heat exchanger and analyzer in operational
association; recovering the coolant gas containing contaminants
from the heat exchanger; delivering an analysis portion of the
recovered coolant gas to the analyzer; analyzing the analysis
portion of the recovered coolant gas with the analyzer to determine
a condition of the recovered coolant gas; blending, based on the
condition, a reclaimed portion of the recovered coolant gas and a
virgin coolant gas to produce a gaseous coolant blend having a
predetermined contaminant concentration; and introducing the
gaseous coolant blend into the heat exchanger such that at least a
portion of the reclaimed recovered coolant gas is recycled.
18. A method of controlling a contaminant concentration in a
gaseous coolant blend provided to a heat exchanger, the method
comprising: providing the heat exchanger and an analyzer, the heat
exchanger and the analyzer in operational association; recovering a
coolant gas containing contaminants from the heat exchanger;
delivering an analysis portion of the recovered coolant gas to the
analyzer; analyzing the analysis portion of the recovered coolant
gas with the analyzer to determine the contaminant concentration
within the recovered coolant gas; and blending, based on the
contaminant concentration, a reclaimed portion of the recovered
coolant gas and a virgin coolant gas to produce the gaseous coolant
blend; recycling the reclaimed portion of the recovered coolant gas
by introducing the gaseous coolant blend into the heat exchanger
such that the contaminant concentration in the gaseous coolant
blend provided to the heat exchanger is controlled.
19. The method of claim 18, wherein the method further comprises
introducing a portion of the recovered coolant gas into a by-pass
section, the by-pass section providing a seal to the heat exchanger
and ensuring continuous operation of a pump.
20. An apparatus for use with a heat exchanger, the apparatus
comprising: a coolant recovery section for recovering a coolant gas
containing contaminants from the heat exchanger; an analysis
section operable to monitor a condition of the recovered coolant
gas; and a coolant gas blending section in operational association
with the coolant gas recovery section and the analysis section, the
coolant gas blending section operable to produce, based on the
condition of the recovered coolant gas, a gaseous coolant blend
having a predetermined contaminant concentration from a virgin
coolant gas and a reclaimed portion of the recovered coolant
gas.
21. The apparatus of claim 20, wherein the coolant gas recovery
section comprises a pump operable to produce both a negative
pressure and a positive pressure within the apparatus.
22. The apparatus of claim 20, wherein the coolant gas recovery
section comprises an orifice capable of reducing, within the heat
exchanger, the effects of pressure differentials created by the
pump.
23. The apparatus of claim 20, wherein the coolant gas blending
section comprises a means for controlling flow.
24. The apparatus of claim 23, wherein the means for controlling
flow is selected from the group consisting of a first and second
flow controller, a first and second mass flow controller, and a
first and second valve.
25. The apparatus of claim 20, wherein the virgin coolant gas
contains less than about 0.005 percent contaminants by volume of
the virgin coolant gas.
26. The apparatus of claim 20, wherein the predetermined
concentration of the contaminants is less than about 5 percent
contaminants by volume of the gaseous coolant blend.
27. The apparatus of claim 20, wherein the condition is selected
from the group consisting of an amount of moisture, a concentration
of oxygen, and a concentration of an inert gas in the recovered
coolant gas.
28. The apparatus of claim 20, wherein the analysis section
includes an analyzer selected from the group consisting of an
oxygen analyzer, an inert gas analyzer, and a moisture
analyzer.
29. The apparatus of claim 20, wherein the apparatus further
comprises a by-pass section for providing a gas seal to the heat
exchanger.
30. The apparatus of claim 29, wherein the by-pass section utilizes
at least a portion of the recovered coolant gas to provide the gas
seal.
31. An apparatus for recovering a coolant gas containing
contaminants from a heat exchanger and recycling at least a portion
of the recovered coolant gas, the apparatus comprising: a pump
operable to recover the coolant gas from the heat exchanger and to
transport the recovered coolant gas through the apparatus; an
analyzer operable to monitor a condition of the recovered coolant
gas; a first mass flow controller operable to reclaim a portion of
the recovered coolant gas by delivering the reclaimed portion of
the recovered coolant gas to a mixing point; a second mass flow
controller operable to provide a virgin coolant gas to the mixing
point; a third mass flow controller operable to maintain a flow of
the recovered coolant gas through the apparatus; wherein the
apparatus is operable to produce, based on the condition of the
recovered coolant gas, a gaseous coolant blend from the virgin
coolant gas and the reclaimed portion of the recovered coolant gas
such that the gaseous coolant blend has a predetermined contaminant
concentration when the gaseous coolant blend is introduced into the
heat exchanger.
32. The apparatus of claim 31, wherein a combined flow of recovered
coolant gas through the first mass flow controller, the third mass
flow controller, and the analyzer determine a pressure generated by
the pump for transporting the recovered coolant gas.
33. The apparatus of claim 31, wherein a flow of the recovered
coolant gas passing through the analyzer is constant.
34. The apparatus of claim 31, wherein the flow of the recovered
coolant gas through the third mass flow controller is restricted
while the flow of the recovered coolant gas through the first mass
flow controller is simultaneously increased.
35. The apparatus of claim 31, wherein the apparatus further
comprises a control system associated with the analyzer and capable
of actuating the first mass flow controller, the second mass flow
controller, and the third mass flow controller based on the
condition of the recovered coolant gas.
36. The apparatus of claim 31, wherein the apparatus further
comprises a control system associated with the analyzer and capable
of actuating the first mass flow controller and the second mass
flow controller to produce the gaseous coolant blend at the
predetermined concentration.
37. The apparatus of claim 31, wherein the apparatus further
comprises an orifice for de-coupling the pump and the heat
exchanger and reducing, within the heat exchanger, pressure
differential effects produced by the pump.
38. A coolant gas recovery system comprising: a coolant gas for
cooling a hot fiber; a heat exchanger including: a fiber inlet
adapted to receive the hot fiber into the heat exchanger; a fiber
outlet adapted to expel the hot fiber from the heat exchanger; a
passageway extending between the fiber inlet and fiber outlet, the
passageway adapted to pass therethrough the hot fiber; one or more
coolant gas inlets for introducing a coolant gas into the
passageway; and one or more coolant gas outlets for removing the
coolant gas from the passageway; a pump for pumping and drawing the
coolant gas through the system; an analyzer for monitoring an
impurity concentration in the coolant gas; a first mass flow
controller and a second mass flow controller for controlling the
impurity concentration in the coolant gas based on the monitored
impurity concentration; and a third mass flow controller for
providing a seal to the heat exchanger using the coolant gas and
for maintaining a constant flow of the coolant gas to ensure
continuous operation of the pump.
39. The system of claim 38, wherein the coolant gas is selected
from the group consisting of helium, nitrogen, a helium-nitrogen
mixture, and a helium-air mixture.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention generally relates to a coolant recovery and
recycling apparatus. In one aspect, the invention relates to a
helium recovery and recycling apparatus associated with a heat
exchanger.
[0003] 2. Description of the Related Art
[0004] In the production of optical fibers, a glass rod or a
"pre-form", which is especially made to manufacture optical fibers,
is processed in an optical fiber drawing system. The optical fiber
drawing system generally comprises a furnace, a heat exchanger, a
coating applicator, a dryer or curing furnace, and a spool as
illustrated in European Patent Application No. 0079188. Initially,
the glass rod is melted in the furnace such that a small,
semi-liquid fiber is produced. The semi-liquid fiber is then cooled
and solidified while falling through the air and the heat
exchanger. Thereafter, the cooled, solidified fiber can be coated
in the coating applicator, dried in the curing furnace or dryer,
and drawn with the spool.
[0005] The drawing rate of the optical fiber is generally dependent
upon the cooling rate of the optical fiber in the heat exchanger.
That is, the rate at which the fiber can be drawn increases as the
rate at which the fiber can be cooled increases. To increase the
cooling rate of the optical fiber, a direct heat exchange process
is employed. In the direct heat exchange process, a coolant gas
(e.g., helium, nitrogen, a helium-nitrogen mixture, a helium-air
mixture, a helium-argon mixture, a helium-hydrogen mixture, a
helium-inert gas mixture, and the like) is introduced into the heat
exchanger where the coolant gas directly encounters and cools the
semi-liquid fiber.
[0006] Typically, the heat exchanger comprises a passageway (e.g.,
generally of a cylindrical configuration) having end openings
(e.g., a fiber inlet and a fiber outlet) for receiving and
expelling the optical fiber, one or more coolant gas inlets for
receiving the coolant gas, and one or more coolant gas outlets for
discharging the coolant gas. The passageway generally extends from
one end opening proximate a top of the heat exchanger to another
end opening proximate a bottom of the heat exchanger. Thus, the
passageway provides a corridor through which the optical fiber can
pass. The coolant gas inlet (or inlets) can introduce coolant gas
into the passageway while the coolant gas outlet (or outlets) can
remove the coolant gas from the passageway. In a conventional
system, a rate of flow of the coolant gas into the heat exchanger
is manipulated and/or controlled with metering valves and flow
meters.
[0007] If any of the spent coolant gas is recovered from the heat
exchanger, typically proximate the outlet, the recovered coolant
gas will typically be entrained with and/or carry impurities,
debris, and the like (collectively "contaminants"). Typical
contaminants include gases (e.g., nitrogen, oxygen, argon, and
other gases present in the atmosphere), particulate substances
(e.g., dust), and moisture. These contaminants can infiltrate the
passageway, coolant gas inlet, and/or coolant gas outlet of the
heat exchanger. The contaminants can collect and increase in
concentration in the recovered coolant gas. The amount and/or
concentration of contaminants in the recovered coolant gas can
limit and/or restrict the amount of coolant gas that can be
recycled and reused.
[0008] In order to reduce the amount and/or concentration of
contaminants in the recovered coolant gas, a variety of solutions
for decontaminating and/or purifying the coolant gas have been
suggested. Coolant gas purification devices, systems, and/or
methods are often employed. Such purification devices and/or
methods are intended to remove some of the contaminants from the
recovered coolant gas so that at least a portion of the recovered
coolant gas can be recycled. However, the use of purification
devices can represent a substantial expense in the optical fiber
manufacturing process.
[0009] Unfortunately, without using a purification device, the
amount of impurities contained within the recovered coolant gas can
be substantial. As attempts are made to recycle more of the
recovered coolant gas, the contaminant concentration within the
recovered coolant gas can resultantly increase. Therefore, a
diminishing amount of recovered coolant gas can be available for
recycling.
[0010] Thus, an efficient and less complex apparatus and method for
recovering and recycling coolant gas would be desirable.
SUMMARY OF THE INVENTION
[0011] In one aspect, the invention provides a method of recovering
and recycling a coolant gas containing contaminants. The method
comprises providing a heat exchanger and an analyzer, the heat
exchanger and the analyzer in operational association. The coolant
gas containing contaminants is recovered from the heat exchanger
and an analysis portion of the recovered coolant gas is delivered
to the analyzer. Thereafter, the analysis portion of the recovered
coolant gas is analyzed with the analyzer to determine a condition
of the recovered coolant gas. Then, based on the condition, a
reclaimed portion of the recovered coolant gas is blended with a
virgin coolant gas to produce a gaseous coolant blend having a
predetermined contaminant concentration. The gaseous coolant blend
is introduced into the heat exchanger such that at least a portion
of the recovered coolant gas is recycled.
[0012] In one embodiment, a method of recovering and recycling a
coolant gas containing contaminants is employed. The method
comprises providing a heat exchanger and an analyzer, the heat
exchanger and analyzer in operational association. The coolant gas
containing contaminants is recovered from the heat exchanger and an
analysis portion of the recovered coolant gas is delivered to the
analyzer. Thereafter, the analysis portion of the recovered coolant
gas is analyzed with the analyzer to determine a condition of the
recovered coolant gas. Then, based on the condition, a reclaimed
portion of the recovered coolant gas is blended with a virgin
coolant gas to produce a gaseous coolant blend having a
predetermined contaminant concentration. The gaseous coolant blend
is introduced into the heat exchanger such that at least a portion
of the reclaimed recovered coolant gas is recycled. In this
embodiment, the reclaimed recovered coolant gas is recycled as
opposed to the recovered coolant gas.
[0013] In another embodiment, a method of controlling a contaminant
concentration in a gaseous coolant blend provided to a heat
exchanger is taught. The method comprises providing the heat
exchanger and an analyzer, the heat exchanger and the analyzer in
operational association. A coolant gas containing contaminants is
recovered from the heat exchanger and an analysis portion of the
recovered coolant gas is delivered to the analyzer. Thereafter, the
analysis portion of the recovered coolant gas is analyzed with the
analyzer to determine the contaminant concentration within the
recovered coolant gas. Then, based on the contaminant
concentration, a reclaimed portion of the recovered coolant gas and
a virgin coolant gas are blended to produce the gaseous coolant
blend. The reclaimed portion of the recovered coolant gas is
recycled by introducing the gaseous coolant blend into the heat
exchanger such that the contaminant concentration in the gaseous
coolant blend provided to the heat exchanger is controlled.
[0014] In a further aspect, the invention provides an apparatus for
use with a heat exchanger. The apparatus comprises a coolant
recovery section, an analysis section, and a coolant gas blending
section. The coolant recovery section is for recovering a coolant
gas containing contaminants from the heat exchanger. The analysis
section is operable to monitor a condition of the recovered coolant
gas. The coolant gas blending section, in operational association
with the coolant gas recovery section and the analysis section, is
operable to produce, based on the condition of the recovered
coolant gas, a gaseous coolant blend having a predetermined
contaminant concentration from a virgin coolant gas and a reclaimed
portion of the recovered coolant gas.
[0015] In one embodiment, an apparatus for recovering a coolant gas
containing contaminants from a heat exchanger and recycling at
least a portion of the recovered coolant gas is disclosed. The
apparatus comprises a pump operable to recover the coolant gas from
the heat exchanger and to transport the recovered coolant gas
through the apparatus and an analyzer operable to monitor a
condition of the recovered coolant gas. The apparatus also
comprises a first mass flow controller operable to reclaim a
portion of the recovered coolant gas by delivering the reclaimed
portion of the recovered coolant gas to a mixing point, a second
mass flow controller operable to provide a virgin coolant gas to
the mixing point, and a third mass flow controller operable to
maintain a flow of the recovered coolant gas through the apparatus.
As such, the apparatus is operable to produce, based on the
condition of the recovered coolant gas, a gaseous coolant blend
from the virgin coolant gas and the reclaimed portion of the
recovered coolant gas. Thus, the gaseous coolant blend has a
predetermined contaminant concentration when the gaseous coolant
blend is introduced into the heat exchanger.
[0016] In yet another aspect, the invention provides a coolant gas
recovery system that comprises a coolant gas for cooling a hot
fiber, a heat exchanger, a pump for pumping and drawing the coolant
gas through the system, an analyzer for monitoring an impurity
concentration in the coolant gas, a first mass flow controller and
a second mass flow controller for controlling the impurity
concentration in the coolant gas based on the monitored impurity
concentration, and a third mass flow controller for providing a
seal to the heat exchanger using the coolant gas and for
maintaining a constant flow of the coolant gas to ensure continuous
operation of the pump.
[0017] The heat exchanger includes a fiber inlet, a fiber outlet, a
passageway, one or more coolant gas inlets, and one or more coolant
gas outlets. The fiber inlet is adapted to receive the hot fiber
into the heat exchanger and the fiber outlet is adapted to expel
the hot fiber from the heat exchanger. The passageway extends
between the fiber inlet and fiber outlet and is adapted to pass
therethrough the hot fiber. The coolant gas inlets are for
introducing a coolant gas into the passageway and the coolant gas
outlets are for removing the coolant gas from the passageway.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Embodiments of the invention are disclosed with reference to
the accompanying drawings and are for illustrative purposes only.
The invention is not limited in its application to the details of
construction, or the arrangement of the components, illustrated in
the drawings. The invention is capable of other embodiments or of
being practiced or carried out in other various ways. Like
reference numerals are used to indicate like components throughout
the drawings.
[0019] FIG. 1 illustrates a schematic flow diagram of an embodiment
of a coolant gas recovery and recycling system according to one
aspect of the invention.
[0020] FIG. 2 illustrates a heat exchanger that can be employed
within the system of FIG. 1.
[0021] FIG. 3 illustrates a chart detailing the optimum flow of
recycled coolant gas that achieves maximum cooling gas recovery
while minimizing the contaminants in the recovered coolant gas
using the system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Various items of equipment, such as fittings, valves,
mountings, pipes, wiring, and the like have been omitted to
simplify the description. However, such conventional equipment and
its uses are known to those skilled in the art and can be employed
as desired. Moreover, although the present invention is described
below in the context of recovering and recycling a coolant gas, the
invention can be employed with, and has applicability to, many
different recovery and/or recycling apparatuses and processes.
[0023] Referring to FIG. 1, a system 10 for recovering and
recycling a coolant gas, such as helium, nitrogen, a
helium-nitrogen mixture, a helium-air mixture, and the like is
shown. System 10 comprises heat exchanger 12, coolant gas recovery
section 14, analysis section 16, and coolant gas blending section
18, which are in operational association with each other.
[0024] Heat exchanger 12, as shown in detail in FIG. 2, can include
a variety of heat exchangers (e.g., direct heat exchanging or like
devices) known in the art that are capable of accepting, receiving,
and/or processing a hot optical fiber, a semi-liquid fiber, and the
like. As shown in FIG. 2, heat exchanger 12 comprises coolant gas
inlet 20, coolant gas outlet 22, passageway 24, and end openings 26
(e.g., a fiber inlet and a fiber outlet). While heat exchanger 12
can include one or more coolant gas inlets 20 and one or more
coolant gas outlets 22, for purposes of illustration, only a single
coolant gas inlet and a single coolant gas outlet are shown in FIG.
2.
[0025] Coolant gas inlet 20 is configured to accept delivery and/or
introduction of coolant gas into heat exchanger 12 while coolant
gas outlet 22 is configured to remove, expel, and/or permit
recovery of the coolant gas from the heat exchanger. Passageway 24
can be formed through heat exchanger 12 and extend between end
openings 26 at opposing ends 28 of the heat exchanger. End openings
26 are structured to receive and discharge the hot optical fiber
from heat exchanger 12. Therefore, passageway 24 and end openings
26 provide the hot optical fiber with a path, corridor, and/or
route in which to pass through heat exchanger 12. Thus, the coolant
gas can be introduced into heat exchanger 12 at coolant gas inlet
20, can flow through or circulate throughout passageway 24, and can
cool the hot optical fiber. Thereafter, the coolant gas can be
removed, drawn, and/or recovered from the heat exchanger at coolant
gas outlet 22.
[0026] Often, coolant gas that is recovered from heat exchanger 12
contains contaminants such as impurities, debris, and the like,
(collectively "contaminants"). These contaminants typically
comprise gases (e.g., nitrogen, oxygen, argon, and other gases
present in the atmosphere), particulate substances (e.g., dust),
and moisture. However, contaminants can include any substance other
than the coolant gas and can exist within the recovered coolant gas
in varying amounts and at varying concentrations.
[0027] In contrast to recovered coolant gas, "virgin" coolant gas
is coolant gas that contains little, if any, contaminants. Virgin
coolant gas such as, for example, an industrial grade virgin
coolant gas, typically contains no more than about 0.005 percent
contaminants by volume.
[0028] Referring back to FIG. 1, coolant gas recovery section 14
includes pump 30, recovery lines 32, and optionally orifice 34 or a
like de-coupling device and/or flow restrictor. Pump 30 is operable
to produce both a negative and a positive pressure within system
10. For example, pump 30 can produce or create the negative
pressure in recovery lines 32a and 32b such that the coolant gas
within heat exchanger 12 can be drawn from the heat exchanger and
recovered. Also, pump 30 can produce or create positive pressure in
one or more lines (i.e., 32c, 32d, and 32e) and elsewhere within
system 10, such that the coolant gas can be pushed or flowed
throughout the system. Any pump capable of producing the negative
and/or positive pressures described above can be employed as pump
30.
[0029] Since pump 30 is operable to generate both negative and
positive pressures, additional pumps, a compressor, and the like
are not needed within system 10. The level and/or amount of
positive pressure generated by pump 30 can be dependent upon the
amount of the coolant gas flowing through system 10 and/or flow
restrictions provided by components of the system.
[0030] Orifice 34 is disposed within system 10, and coolant gas
recovery section 14, such that the orifice can de-couple heat
exchanger 12 from pump 30. Orifice 34 is also capable of
controlling and/or reducing the effects of pressure differentials
within heat exchanger 12. These pressure differentials are created
by pump 30 as the pump operates to produce both positive and
negative pressures within system 10. If not controlled, the
pressure differentials (i.e., fluctuations in pressure) can produce
undesirable fiber vibrations. Undesirable fiber vibrations can
adversely affect the fiber-drawing process and the quality of the
optical fiber that is produced.
[0031] Analysis section 16 includes an analyzer 36 and analysis
line 38. Analyzer 36 can comprise one or more of a variety of
analyzers or monitors known in the art such as, for example, an
oxygen analyzer, a helium analyzer, a nitrogen analyzer, a moisture
analyzer, and the like. Analyzer 36 can be associated, though
recovery lines 32 and analysis line 38, with heat exchanger 12 such
that the analyzer is operable to monitor a condition of the
recovered coolant gas (or an analysis portion of the recovered
coolant gas) drawn from the heat exchanger. Conditions of the
recovered coolant gas that can be monitored include, but are not
limited to, an amount and/or concentration of oxygen, an amount
and/or concentration of helium, an amount and/or concentration of
nitrogen, an amount and/or concentration of another inert gas, and
an amount of moisture in the recovered coolant gas.
[0032] Preferably, analyzer 36 is operationally associated with a
control system 37. Control system 37 is operable to relay and/or
transmit the condition monitored by the analyzer to one or more
components of system 10 (e.g., mass flow controllers, flow
controllers, valves, and the like). Control system 37 can further
operate to instruct and/or control one or more mass flow
controllers, based on the monitored, relayed, and/or transmitted
condition, regarding flow rates and other operational
parameters.
[0033] Coolant gas blending section 18 includes flow or mass flow
controllers 40 and 42, virgin line 44, reclaimed line 46, and blend
line 48. Mass flow controller 40 is operable to permit or restrict
a flow of the recovered coolant gas. Specifically, the recovered
coolant gas can be selectively permitted to pass through mass flow
controller 40 and into reclaimed line 46 whereby the recovered
coolant gas is "reclaimed". The reclaimed coolant gas can then flow
through reclaimed line 46 to mixing point 50.
[0034] Mass flow controller 42 is operable to permit or restrict a
flow of the virgin coolant gas. Specifically, the virgin coolant
gas can be permitted to pass through mass flow controller 42 and
into virgin line 44. The virgin coolant gas can then flow through
virgin line 44 to mixing point 50.
[0035] Mixing point 50, as shown in FIG. 1, occurs at the
intersection of virgin line 44, reclaimed line 46, and blend line
48. At mixing point 50, the reclaimed coolant gas and the virgin
coolant gas can be blended together to produce a mixture and/or
blend of coolant gas at a predetermined and/or desired purity. In
other words, the blend of coolant gas can be produced such that the
blend has a predetermined, known, and/or desired contaminant
concentration (collectively "predetermined contaminant
concentration").
[0036] Typically, the predetermined contaminant concentration of
the blend coolant gas is less than about five percent (5%)
contaminants by volume of the blend coolant gas. Correspondingly,
the coolant gas recycled by system 10 has a coolant gas
concentration (i.e., purity) of about ninety-five to about
ninety-nine percent (about 95 to about 99%) coolant gas by volume
of the blend coolant gas. In preferred embodiments, the
predetermined contaminant concentration and the coolant gas
concentration in the blend coolant gas can be user defined.
[0037] In one embodiment, the predetermined contaminant
concentration can be achieved by selectively operating mass flow
controllers 40 and 42 to blend varying amounts of reclaimed coolant
gas and virgin coolant gas together in an appropriate proportion.
The blend coolant gas can be produced using this "blending" method
since the contaminant concentration within the virgin coolant gas
is generally known and the analyzer can determine the contaminant
concentration within the recovered coolant gas.
[0038] Once the blend coolant gas is produced at mixing point 50,
the blend coolant gas is passed through blend line 48 for
introduction into heat exchanger 12. As such, the blend coolant
gas, and more specifically the reclaimed portion of the recovered
coolant gas, is "recycled". The heat exchanger can use the recycled
coolant gas to cool a hot optical fiber as previously described
and, since the blend coolant gas, which includes the reclaimed
portion of the recovered coolant gas, is recycled and/or reused, a
significant cost savings can be realized.
[0039] In preferred embodiments, system 10 also includes by-pass
section 52. By-pass section 52 includes mass flow controller 54 and
one or more seal lines 56a-b. Mass flow controller 54 is operable
to permit or restrict a flow of the recovered coolant gas through
seal line 56a. The recovered coolant gas can flow through analyzer
36, analysis line 38, and seal lines 56a-b until passing proximate
ends 28 of heat exchanger 12 such that seals 58a-b are formed.
Seals 58a-b can comprise, for example, a conventional gas seal.
Thus, by-pass section 52 can inhibit and/or prevent undesirable
escape of the coolant gas from within passageway 24 of heat
exchanger 12 and, in doing so, utilize a portion of the recovered
coolant gas.
[0040] In an exemplary embodiment, seals 58a-b comprise seals such
as those described in commonly-owned, co-pending U.S. patent
application Ser. No. 09/998,288 filed Nov. 30, 2001, entitled "Cap
Assembly and Optical Fiber Cooling Process" and, therefore, the
contents and disclosure of that application are incorporated into
the present application by this reference as if fully set forth
herein.
[0041] Further, by-pass section 52, and particularly mass flow
controller 54, can operate to maintain a constant flow of at least
a portion of the recovered coolant gas through system 10. The
constant flow can resultantly ensure that pump 30 continually
operates. With a continually operating pump 30, positive pressure
generated by the pump, which transports the recovered, reclaimed,
and blended coolant gas through system 10, can be maintained. By
maintaining the positive pressure in system 10, "lag time" can be
reduced. As used herein, lag time is essentially that amount of
time that elapses while the recovered coolant gas progresses
through system 10 (e.g., through lines 32d and 38 to reach analyzer
36).
[0042] Lag time is often undesirably noticed and/or experienced
when diverting and/or redirecting flows of the coolant gas from
line to line (e.g., 56 and 46) within system 10. For example, when
mass flow controller 54 restricts the flow of a portion of the
recovered coolant gas entering seal line 56a, and mass flow
controller 40 simultaneously permits an increased flow of a portion
of the recovered coolant gas through reclaimed line 46, lag time
might be expected. However, because pump 30 has been continually
operating, a build-up of positive pressure is not necessary to
divert and/or redirect the recovered coolant gas. Therefore, the
portion of the recovered coolant gas that had been entering seal
line 56a can be quickly diverted to reclaimed line 46. When
positive pressure within system 10 is not allowed to substantially
dissipate as a result of the continuously and/or continually
operating pump, lag time can be reduced.
[0043] Advantageously, by-pass section 52 can also inhibit and/or
prevent accumulation of contaminants upstream of mass flow
controller 40 that are caused by a decreasing flow of recovered
coolant gas at an increasing concentration of the recovered coolant
gas.
[0044] In operation, a coolant gas having contaminants is drawn
(i.e., recovered) from heat exchanger 12 by operating pump 30. The
recovered coolant gas enters recovery line 32a and flows through
orifice 34, recovery line 32b, pump 30, and recovery line 32c.
While progressing through recovery line 32c, the coolant gas having
contaminants is divided and/or splits such that at least a portion
of the recovered coolant gas flows through recovery line 32d and
another portion flows through recovery line 32e.
[0045] Of the portion of the recovered coolant gas flowing through
recovery line 32d, an analysis portion enters analysis line 38 and
is introduced into analyzer 36 and a portion passes through mass
flow controller 54. Preferably, the flow of the portions of
recovered coolant gas through each of analyzer 36 and mass flow
controller 54 are constant or substantially constant while the flow
of recovered coolant gas through recovery line 32e and mass flow
controller 40 is variable.
[0046] Positive pressure generated by pump 30 can be directly
related and/or depend upon a combination of the flows of recovered
coolant gas through analyzer 36 and mass flow controllers 40 and
54. In other words, pump 30 can operate to produce as much or as
little positive pressure as needed depending on a summation of flow
restrictions produced by analyzer 36 and mass flow controllers 40
and 54.
[0047] After the recovered coolant gas has been divided, analyzer
36 operates to monitor a condition of the analysis portion of the
recovered coolant gas and, as such, can determine the contaminant
concentration within the recovered coolant gas. Thereafter,
analyzer 36 and/or control system 37 transmits and/or relays the
concentration information to one or more of mass flow controllers
40, 42, and 54. Analyzer 36 and/or control system 37 can also, if
desired, instruct and/or control one or more of mass flow
controllers 40, 42, and 54 to manipulate flows of the recovered
coolant gas.
[0048] Having determined the contaminant concentration of the
recovered coolant gas with analyzer 36, and knowing the contaminant
concentration within the virgin coolant gas, mass flow controller
40 and 42 are actuated and/or operated. When mass flow controller
42 is actuated, an amount of the virgin coolant gas travels through
virgin line 44 and is delivered to mixing point 50. Also, when mass
flow controller 40 is actuated, an amount of recovered coolant gas
is permitted to pass through the mass flow controller such that the
amount of the recovered coolant gas is reclaimed. The reclaimed
coolant gas travels through reclaimed line 46 and is also delivered
to mixing point 50.
[0049] At mixing point 50, the reclaimed coolant gas and the virgin
coolant gas are blended and/or mixed together to produce the blend
coolant gas (i.e., gaseous coolant blend) having the predetermined
contaminant concentration or coolant gas purity. Thus, the quality
of the coolant gas (i.e., the contaminant concentration or purity),
as opposed to quantity (i.e., rate of flow) of the coolant gas, is
manipulated and/or controlled by system 10, and particularly mass
flow controllers 40 and 42.
[0050] After the blend coolant gas, at the predetermined
concentration, has been produced, the blend coolant gas is passed
through blend line 48 until entering heat exchanger 12 under the
positive pressure of pump 30. As such, the blend coolant gas, and
specifically the recovered coolant gas that was reclaimed, is
"recycled" by once again using or employing the blend coolant gas
and/or the recovered coolant gas within heat exchanger 12 to cool
the optical fiber.
[0051] When coolant gas is recycled using system 10, the
concentration of the blend coolant gas can be predetermined and the
flow rate of the blend coolant gas into heat exchanger 12 can
remain substantially constant. For example, if the recovered
coolant gas contains a relatively high contaminant concentration,
then less of the recovered coolant gas and more of the virgin
coolant gas are blended together to produce the mixture possessing
the desired level of contaminants. Conversely, if the recovered
coolant gas contains a relatively low contaminant concentration,
then more of the recovered coolant gas and less of the virgin
coolant gas are blended together to produce the mixture possessing
the desired level of contaminants.
[0052] Additionally, because the steps of recovering and reclaiming
coolant gas can be performed repeatedly within system 10, it is
important to note that the lower the flow of reclaimed coolant gas
the lower the contaminant concentration that will be entrained in
the recovered coolant gas.
[0053] Also, no matter what the ratio of reclaimed coolant gas to
virgin coolant gas may be when the blend coolant gas having the
predetermined contaminant concentration is produced, the flow rate
of the blend coolant gas into heat exchanger 12 can stay the same
or substantially the same. Thus, the flow rate of the blend coolant
gas into heat exchanger 12 does not depend upon the contaminant
concentration in the recovered or reclaimed coolant gas.
[0054] Preferably, the amount of recovered coolant gas that is
reclaimed and used to produce the blended coolant gas is optimized
to ensure that the maximum amount of recovered coolant gas is
reclaimed and then recycled. In one embodiment, optimization can be
achieved by solving a system of flow and concentration equations.
Such optimization, with reference to FIG. 1, is described
below.
[0055] First, the impurity concentration of the recovered coolant
gas, y.sub.r, is determined by analyzer 36. Then, mass flow
controller 42 receives the virgin coolant gas flowing at f.sub.v
and having impurity concentration y.sub.v and mass flow controller
40 receives the recovered coolant gas flowing at f.sub.r and having
impurity concentration y.sub.r. Blending section 18 operates such
that the blended coolant gas having flow f.sub.p with impurity
y.sub.p is produced. The blended coolant gas flow f.sub.p can be
determined by:
f.sub.p=f.sub.v+f.sub.r (1)
[0056] while the impurity concentration y.sub.p of the blended
coolant gas is governed by:
y.sub.pf.sub.p=y.sub.vf.sub.v+y.sub.rf.sub.r (2)
[0057] Having or knowing desired values for f.sub.p and y.sub.p,
ascertaining y.sub.r with analyzer 36, and knowing the impurity
concentration within virgin coolant gas y.sub.v, both f.sub.r and
f.sub.v can be solved for using the blended coolant gas flow and
impurity concentration equations (1) and (2). As a result, f.sub.p
at a desired concentration y.sub.p can be achieved by manipulating
the recovered coolant gas flow f.sub.r and virgin coolant gas flow
f.sub.v according to the equations: 1 f r ( y r ) = f p y p - y v y
r - y v f v ( y r ) = f p y r - y p y r - y v
[0058] Since the impurity concentration of the recovered coolant
gas y.sub.r was found to be dependent upon suction flow f.sub.s in
recovery line 32a when f.sub.s is less than f.sub.r, the y.sub.r
dependence on f.sub.s can be directly determined by introducing
virgin coolant gas that is 100% pure (e.g., substantially free of
or lacking contaminants) into heat exchanger 12 such that:
y.sub.p=y.sub.v=0
[0059] The resulting impurity concentration of the recovered
coolant gas y.sub.r can then be measured for varying f.sub.s values
such that:
y.sub.r.sup.0=y.sub.r.sup.0(f.sub.s)
[0060] Then, the impurity concentration of the recovered coolant
gas Yr fulfills:
y.sub.r(f.sub.s)=y.sub.p+(1-y.sub.p)y.sub.r.sup.0(f.sub.s)
[0061] Referring to FIG. 3, the dependencies y.sub.r (f.sub.s) and
f.sub.r (y.sub.r) are illustrated. At the maximum recovery rate,
each equation:
y.sub.r(f.sub.s)=y.sub.p+(1-y.sub.p)y.sub.r.sup.0(f.sub.s) 2 f r (
y r ) = f p y p - y v y r - y v
[0062] is fulfilled and, therefore, the optimum recovered gas flow,
f.sub.r.sup.opt, with the impurity concentration, y.sub.r.sup.opt,
occurs at the intersection point of the two curves produced when
the above equations are solved. Thus, the optimum recovered gas
flow at the optimum concentration can be achieved.
[0063] When employed, system 10 can provide numerous advantages.
For example, system 10 can continually maintain an increased or
elevated rate of coolant gas recovery and can reduce contamination
in the recovered coolant gas by reducing suction flow. Further,
system 10 can insure and/or promote a constant flow of coolant gas,
f.sub.p, at a constant concentration. In other words, there is
typically no "toggling" between only virgin gas and blended gas.
Additionally, the use of system 10 can avoid the need for a
variable speed pump, blower, or other means for controlling suction
pressure. System 10 does not require coolant gas venting in order
to control the fiber-cooling process and no pressure or vacuum
measurements need to be taken. Notably, each of these advantages is
accomplished without unnecessary or extraneous equipment added to,
or employed within, system 10.
[0064] Despite any methods being outlined in a step-by-step
sequence, the completion of acts or steps in a particular
chronological order is not mandatory. Further, elimination,
modification, rearrangement, combination, reordering, or the like,
of acts or steps is contemplated and considered within the scope of
the description and appended claims.
[0065] While the present invention has been described in terms of
the preferred embodiment, it is recognized that equivalents,
alternatives, and modifications, aside from those expressly stated,
are possible and within the scope of the appended claims.
* * * * *