Claims:CLAIMS

What is claimed is:

1. An optical fiber draw tower (100) comprising:

a draw tower body (106) for passage of an optical fiber (104) through a tower length; and

a gas recovery unit (108) placed at a bottom end of the optical fiber draw tower (100), wherein the gas recovery unit (108) has a pre-defined shape defined by a variable width along axis of the optical fiber draw tower (100).

2. The optical fiber draw tower (100) as claimed in claim 1, wherein the optical fiber (104) is drawn from the draw tower body (106) at a fiber draw speed of greater than 2000 meter per minute.

3. The optical fiber draw tower (100) as claimed in claim 1, wherein a top width of an upper region (110) of the gas recovery unit (108) is less than a middle width of a middle region (112) of the gas recovery unit (108).

4. The optical fiber draw tower (100) as claimed in claim 1, further comprising a first set of openings (116) and a second set of openings (118), wherein the first set of openings (116) and the second set of openings (118) are connected to a negative pressure reservoir.

5. The optical fiber draw tower (100) as claimed in claim 1, further comprising a first set of openings (116) and a second set of openings (118), wherein the first set of openings (116) are placed in a middle region (112) of the gas recovery unit (108) and the second set of openings (118) are placed in a lower region (114) of the gas recovery unit (108).

6. The optical fiber draw tower (100) as claimed in claim 1, further comprising a first set of openings (116) and a second set of openings (118), wherein a diameter of the first set of openings (116) is greater than a diameter of the second set of openings (118).

7. The optical fiber draw tower (100) as claimed in claim 1, wherein the gas recovery unit (108) further comprises an interrupter (120) to block flow of gas and direct gas towards a middle width of a middle region (112) of the gas recovery unit (108).

8. The optical fiber draw tower (100) as claimed in claim 1, wherein the gas recovery unit (108) further comprises an interrupter (120), wherein the interrupter (120) has an inverted U shape and has an opening for passage of the optical fiber (104), wherein the inverted U shape of the interrupter (120) helps in redirecting gas flow towards peripheral portions.

9. The optical fiber draw tower (100) as claimed in claim 1, wherein extraction of gas is selective, wherein the extraction of gas is done for Helium/cooling gas and not air because of pre-defined placement and pre-defined sizes of a first set of openings (116) and a second set of openings (118).

10. The optical fiber draw tower (100) as claimed in claim 1, further comprising a first set of openings (116) and a second set of openings (118), wherein a diameter of the first set of openings (116) is in a range of 15 to 20 mm, wherein a diameter of the second set of openings (118) is in a range of 9 to 11 mm.
, Description:TECHICAL FIELD
[0001] The present invention related to the field of optical fibers, and more particularly to a helium recovery apparatus with unique placement of suction ports at pre-defined locations.

BACKGROUND
[0002] With the ever-growing advancement of science and technology, various modern technologies are being employed to recover gases from fiber drawing apparatus. One of the most important modern technologies is to recover helium gas from an optical fiber draw tower. The optical fiber draw tower includes an optical fiber preform which is heated at a high temperature to provide an optical fiber. The optical fiber preform is a multi-layer and pure glass cylinder in structure. A furnace in the optical fiber draw tower heats the base end of the optical fiber preform to melt glass fiber until a droplet slowly descends. In addition, helium filled cooling tube helps to reduce the temperature before coating is applied. It is important to recover helium as efficiently as possible without changing the parameters of the fiber. The conventional methods focus more on the fiber drawing and thus, decrease the helium residence time in the gas recovery unit. The lower residence time of helium in the gas recovery unit leads to inefficient and comparatively less helium recovery.

[0003] There are a few patent applications that provide helium recovery apparatus. In an example, a patent application CN203700194U discloses a system comprising a helium recovery unit. The recovery unit includes a gas collecting tank, a pressurizing pump, a flowmeter and the like. In another example, the patent application JPS60103006A discloses a tilted apparatus formed by mounting a cold tank, filter, a compressor, a dryer, a vacuum pump and a portable vessel. In yet another example, the patent application EP0879389A4 discloses spent gases rather than being vanted drawn off through a recovery line, a sensor, an automatic valve, a compressor to helium purifier. In yet another example, the patent application EP0879389B1 discloses helium of a first purity fed to a consolidation furnace and waste helium recovered from the furnace and fed to a helium purifier. However, all the above stated examples have a different configuration structurally.

[0004] In the light of above stated discussion, there is a need of helium recovery apparatus with better efficiency of helium recovery.

OBJECT OF THE DISCLOSURE
[0005] A primary object of the present disclosure is to provide a helium recovery apparatus with unique placement of suction ports at pre-defined locations.

[0006] Another objective of the present disclosure is to provide uniquely designed dimensions for a first set and second set of suction ports for efficient recovery of helium.

[0007] Another objective of the present disclosure is to increase residence time of helium to increase the helium recovery efficiency.

[0008] Another objective of the present disclosure is to provide difference in size of suction openings to create recovery of helium gas compared to air.

SUMMARY

[0009] In an aspect, the present disclosure provides an optical fiber draw tower. The optical fiber draw tower includes a draw tower body for passage of an optical fiber through a tower length. In addition, the optical fiber draw tower includes a gas recovery unit placed at a bottom end of the optical fiber draw tower. The gas recovery unit has a pre-defined shape defined by a variable width along axis of the optical fiber draw tower.

STATEMENT OF THE DISCLOSURE

[0010] The present disclosure provides an optical fiber draw tower. The optical fiber draw tower includes a draw tower body for passage of an optical fiber through a tower length. In addition, the optical fiber draw tower includes a gas recovery unit placed at a bottom end of the optical fiber draw tower. The gas recovery unit has a pre-defined shape defined by a variable width along axis of the optical fiber draw tower.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0012] FIG. 1 illustrates a cross sectional view of an exemplary optical fiber draw tower, in accordance with various aspects of the present disclosure; and

[0013] FIG. 2 illustrates a cross sectional view of an exemplary gas recovery unit placed at a bottom end of the optical fiber draw tower, in accordance with an aspect of the present disclosure.

[0014] It should be noted that the accompanying figures are intended to present illustrations of exemplary aspects of the present disclosure. These figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.

DETAILED DESCRIPTION
[0015] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present technology. It will be apparent, however, to one skilled in the art that the present technology can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only in order to avoid obscuring the present technology.

[0016] Reference in this specification to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect of the present technology. The appearance of the phrase “in one aspect” in various places in the specification are not necessarily all referring to the same aspect, nor are separate or alternative aspects mutually exclusive of other aspects. Moreover, various features are described which may be exhibited by some aspects and not by others. Similarly, various requirements are described which may be requirements for some aspects but not other aspects.

[0017] Moreover, although the following description contains many specifics for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to said details are within the scope of the present technology. Similarly, although many of the features of the present technology are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the present technology is set forth without any loss of generality to, and without imposing limitations upon, the present technology. Although the following description provides an optical fiber cable, the shown cable construction method can be applied to any cable with loose tube and sheath.

[0018] It should be noted that the terms "first", "second", and the like, herein do not denote any order, ranking, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[0019] FIG. 1 illustrates a cross sectional view of an exemplary optical fiber draw tower 100, in accordance with various aspects of the present disclosure. The optical fiber draw tower 100 includes an optical fiber preform 102, an optical fiber 104, a draw tower body 106 and a gas recovery unit 108. In addition, the gas recovery unit 108 includes an upper region 110, a middle region 112, a lower region 114, a first set of openings 116, a second set of openings 118 and an interrupter 120. In an aspect, a top width of the upper region 110 of the gas recovery unit 108 is less than a middle width of the middle region 112 of the gas recovery unit 108. The gas recovery unit 108 is divided into three regions namely the upper region 110, the middle region 112 and the lower region 114. The upper region 110 constitutes a first area of the gas recovery unit 108 from where the optical fiber 104 enters the gas recovery unit 108 first. The middle region 112 constitutes a second area of the gas recovery unit 108 from where the optical fiber 104 continues to pass after travelling through the upper region 110 of the gas recovery unit 108. The lower region 114 constitutes a third area of the gas recovery unit 108 from where the optical fiber 104 continues to pass after travelling through the upper region 110 and the middle region 112 of the gas recovery unit 108. The upper region 110, the middle region 112 and the lower region 114 define a shape of the gas recovery unit 108. The gas recovery unit 108 has a variable width. The shape of the gas recovery unit 108 is such that the width of the gas recovery unit 108 increases from the upper region 110 to the middle region 112 and then decreases from the middle region 112 to the lower region 114.

[0020] The optical fiber draw tower 100 allows fabrication of an optical fiber 104 during a fiber drawing process. In general, fiber drawing includes heating a macro structured preform and drawing extended lengths of micro-structured fiber. In an aspect, the optical fiber preform 102 is heated to draw extended lengths of the optical fiber 104. The optical fiber preform 102 is manufactured to produce the ultra-low loss optical fiber 104 through conventional drawing methods. The drawn optical fiber 104 is a fiber used for transmitting information as light pulses from one end to another. The drawn optical fiber 104 is a thin strand of glass capable of transmitting optical signals. In addition, the drawn optical fiber 104 allows transmission of information in the form of optical signals over long distances. The drawn optical fiber 104 has desired characteristics. The optical fiber 104 is heated inside a furnace and travels through a length of the draw tower body 106.

[0021] In an aspect, the draw tower body 106 allows passage of the optical fiber 104 through the optical fiber draw tower 100 length. In an aspect, the optical fiber 104 is drawn from the draw tower body 106 at a fiber draw speed of greater than 2000 meter per minute. Alternatively, the fiber draw speed of the optical fiber 104 may vary. In an aspect, the helium gas dragging increases with the increase in the fiber draw speed. The optical fiber 104 takes up all the helium gas along with it during exit and results in a drop in the helium recovery. In an aspect, the gas recovery unit 108 recovers above 70% of the helium gas as compared to earlier 30% even at more than 2000 draw speed.

[0022] The optical fiber preform 102 is a large cylindrical body of glass having a core structure and a cladding structure. In addition, the optical fiber preform 102 is a material used for fabrication of the optical fiber 104. Accordingly, the optical fiber 104 is used for a variety of purposes. The variety of purposes includes telecommunications, broadband communications, medical applications, military applications and the like. The optical fiber preform 102 is the optical fiber 104 in a large form.

[0023] The core section is an inner part of the optical fiber preform 102 or the optical fiber 104 and the cladding section is an outer part of the optical fiber preform 102 or the optical fiber 104. Moreover, the core section and the cladding section are formed during the manufacturing stage of the optical fiber preform 102. The core section has a refractive index which is greater than a refractive index of the cladding section. In general, the core section has a higher refractive index than the cladding section. The refractive index is maintained as per a desired level based on a concentration of chemicals used for the production of the optical fiber preform 102.

[0024] The optical fiber preform 102 is associated with a longitudinal axis. The longitudinal axis is an imaginary axis passing through geometrical center of the optical fiber preform 102. The optical fiber preform 102 includes a core section and a cladding section. The core section is inner part of the optical fiber preform 102. The cladding section is an outer part of the optical fiber preform 102. The core section is defined as a region around the longitudinal axis of the optical fiber preform 102. The core section extends radially outward from the longitudinal axis of the optical fiber preform 102.

[0025] The optical fiber 104 passes through to the draw tower body 106. The draw tower body 106 is connected to the gas recovery unit 108. The draw tower body 106 allows the passage of the optical fiber 104 from the optical fiber preform 102 to the gas recovery unit 108. In an aspect, the optical fiber 104 obtained is in the form of glass. In another aspect, the optical fiber 104 may be in any other form.

[0026] In an aspect, a furnace heats the base of the optical fiber preform 102 to melt the optical fiber 104 in glass form. In addition, a helium gas filled coating tube is applied to the optical fiber 104 drawn to reduce the temperature before a coating is applied. Further, the helium gas and the optical fiber 104 is passed on to the gas recovery unit 108 in the direction as shown in FIG. 1. Furthermore, the gas cools the molten optical fiber 104, flows from the upper region 110 towards the lower region 114 and has a positive pressure.

[0027] FIG. 2 illustrates a cross sectional view of the gas recovery unit 108, in accordance with an aspect of the present disclosure. The gas recovery unit 108 is used to recover helium gas from the draw tower body 106 (references been made to FIG. 1). In addition, the gas recovery unit 108 includes the upper region 110, the middle region 112, the lower region 114, the first set of openings 116, the second set of openings 118 and an interrupter 120. Further, the first set of openings 116 and the second set of openings 118 are connected to a negative pressure reservoir. In general, the negative pressure reservoir is a condition whereby the air pressure is lower in one place as compared to the other. In an example, the negative pressure reservoir is used in a collection tank. The negative pressure reservoir is placed outside the optical fiber draw tower 100 to collect the extracted helium gas.

[0028] The gas recovery unit 108 is placed at a bottom end of the optical fiber draw tower 100. The gas recovery unit 108 has a pre-defined shape defined by a variable width along axis of the optical fiber draw tower 100. The variable width corresponds to a change in width from the upper region 110 to the lower region 114. In an aspect of the present disclosure, the gas recovery unit 108 is divided into three equal regions - the upper region 110, the middle region 112 and the lower region 114. The first set of openings 116 are a part of the middle region 112 as the placement of the first set of openings 116 in the upper region 110 or the lower region 114 leads to early recovery of the helium gas which is undesirable. In addition, the placement of the first set of openings 116 in the upper region 110 or the lower region 114 reduces the stay time of the optical fiber 104 in the helium gas environment.

[0029] Further, the second set of the openings 118 are a part of the lower region 114 of the gas recovery unit 108 as the placement of the second set of openings 118 in any other region will not lead to absorption of the helium gas and air. The diameter of the first set of openings 116 is larger than the diameter of the second set of openings 118. The helium gas is lighter than air resulting in greater diameter openings in the middle region 112 compared to the lower region 114. The greater diameter of the middle region 112 helps in selective recovery of the helium gas. In an aspect of the present disclosure, the diameter of the first set of openings 116 is in a range of 15 to 20 mm. In an aspect of the present disclosure, the diameter of the second set of openings 118 is in a range of 9 to 11 mm. In an aspect, the shape of the gas recovery unit 108 is an inverted cone shape. In another aspect, the shape of the gas recovery unit 108 may be different.

[0030] The inverted cone shape of the gas recovery unit 108 increases residence time of the helium gas in the gas recovery unit 108. The increase in residence time of the helium gas increases the efficiency of gas recovery in the gas recovery unit 108.

[0031] In an aspect of the present disclosure, the first set of openings 116 are placed in the middle region 112 of the gas recovery unit 108 and the second set of openings 118 are placed in the lower region 114 of the gas recovery unit 108. In an aspect, the first set of openings 116 and the second set of openings 118 are suction ports. The suctions ports recover the helium gas along with the optical fiber 104. In addition, the collected helium gas is sent to a gas collection zone. Further, the optical fiber 104 drawn is sent to an annealing zone.

[0032] In an aspect, the size of the first set of openings 116 is larger than the size of the second set of openings 118. In addition, the first set of openings 116 placed around the middle region 112 are broad suction ports. Further, the second set of openings 118 around the lower region 114 are narrow suction ports in size. The difference in the size of the openings enables selective recovery of the helium gas as compared to air. As a result, the amount of helium gas recovered increases in the gas recovery unit 108.

[0033] The placement of the first set of openings 116 and the second set of openings 118 allows extraction of only cooling gases and not air. The placement of suction ports allows increased extraction of the helium gas. In an aspect, the helium gas recovery rate achieved at the gas recovery unit 108 is 70%. In another aspect, the helium gas recovery rate achieved at the gas recovery unit 108 may be different. In an aspect of the present disclosure, the extraction of gas is selective. The extraction of gas is done for Helium/cooling gas and not air because of pre-defined placement and pre-defined sizes of the first set of openings 116 and the second set of openings 118. In an aspect, more than 70% of the helium gas is recovered with the above mentioned placement of the first set of openings 116 and the second set of openings 118.

[0034] The amount of helium gas drawn by the gas collection zone is not equal to the amount of total helium gas passed in the optical fiber draw tower 100. In an aspect, the amount of helium gas returning back to the draw tower body 106 meets with the interrupter 120. The interrupter 120 is placed above the middle region 112, more towards the upper region 114. The interrupter 120 redirects the flow of the helium gas towards the second set of openings 118. In an aspect, the interrupter 120 blocks flow of gas and directs gas towards the middle width of the middle region 112 of the gas recovery unit 108. In addition, the interrupter 120 increases the amount of stay time of the helium gas and increases the amount of helium gas recovered from the gas recovery unit 108. In an aspect, the interrupter 120 has an inverted U shape. In another aspect, the interrupter 120 has any shape, structure, configuration to re-direct the flow of the helium gas towards the gas recovery unit 108. Further, the interrupter 120 has an opening in the center to allow passage of the optical fiber 104. The interrupter 120 has an opening for passage of the optical fiber 104. The inverted U shape of the interrupter 120 helps in redirecting gas flow towards peripheral portions.

[0035] The foregoing descriptions of specific aspects of the present technology have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present technology to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The aspects were chosen and described in order to best explain the principles of the present technology and its practical application, to thereby enable others skilled in the art to best utilize the present technology and various aspects with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present technology.

[0036] While several possible aspects of the invention have been described above and illustrated in some cases, it should be interpreted and understood as to have been presented only by way of illustration and example, but not by limitation. Thus, the breadth and scope of a preferred aspect should not be limited by any of the above-described exemplary aspects.