Patent Application
20140144184
The disclosure relates generally to producing glass products and more particularly to restricting hydrogen permeation through the wall of an article which may be used in producing the glass products.
Gaseous glass defects in the form of oxygen-rich blisters may be introduced into glass while it is being manufactured. During manufacturing, these blisters may form at an interface between the molten glass and an adjacent platinum wall. The blisters may form in response to hydrogen permeating through the platinum wall. Therefore, the blistering may be referred to as hydrogen permeation blistering.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinency of any cited documents.
An embodiment of the disclosure relates to a method for processing molten glass, comprising having face-to-face contact between the molten glass and an outer surface of an article, and restricting any inward hydrogen permeation through the article. The article may comprise noble metal, and an inner surface of the article may extend around an interior space of the article. The restricting of any inward hydrogen permeation through the article may comprise having media in the interior space, wherein the media is effective for restricting any inward hydrogen permeation through the article.
In one example, the restricting of any inward hydrogen permeation through the article may comprise having fluid in the interior space, wherein the fluid is in face-to-face contact with the inner surface of the article, and the fluid is for restricting any inward hydrogen permeation through the article. In one aspect, the fluid may fill the interior space of the article to at least the level of the molten glass that is outside of the article. In this and/or another aspect, the fluid may fill at least about 33% of a volume of a length of the interior space. The fluid in the interior space may restrict any inward hydrogen permeation through the article as a result of the fluid providing a partial pressure of hydrogen at the face-to-face contact between the inner surface of the article and the fluid, and that partial pressure may be at least about the same as any partial pressure of hydrogen provided by the molten glass at the face-to-face contact between the molten glass and the outer surface of the article. The fluid in the interior space of the article may comprise be a liquid such as, but not limited to, molten glass. The interior space may have a dimension (e.g., a maximal crosswise dimension) that extends crosswise to the length, wherein the crosswise dimension is defined between opposite portions of the inner surface of the article, and the crosswise dimension may be smaller than the length. The crosswise dimension may be a diameter defined between diametrically opposite portions of the inner surface of the article, and the diameter may be smaller than the length.
In another example, the restricting of any inward hydrogen permeation through the article may comprise causing fluid to flow in the interior space, so that the fluid is in face-to-face contact with the inner surface of the article, wherein the fluid is for restricting any inward hydrogen permeation through the article. More specifically, the fluid may be circulated in the interior space, and the fluid may have a partial pressure of hydrogen that may be at least about the same as any partial pressure of hydrogen provided by the molten glass at the face-to-face contact between the outer surface of the article and the molten glass. The fluid flowing within the interior space of the article may be gas.
In one example, the molten glass may be contained in a stirring chamber. The article may be any suitable device such as, but not limited to, a tubular stirrer that may have one or more stirring elements extending outwardly therefrom. The molten glass in the stirring chamber may be stirred with the stirrer.
An additional embodiment of the disclosure relates to an apparatus for being in contact with molten glass, wherein the apparatus comprises an article comprising noble metal, the article has opposite inner and outer surfaces, the outer surface is for being in face-to-face contact with the molten glass, and the inner surface extends around an interior space of the article; and a glass filling may be in face-to-face contact with the inner surface of the article. The glass filling may fill at least about 33% of a volume of a length of the interior space. The length of the interior space may have a crosswise dimension (e.g., a maximal crosswise dimension) defined between opposite portions of the inner surface of the article, and the crosswise dimension may be smaller than the length. As a more specific example, the length of the interior space may have a diameter defined between diametrically opposite portions of the inner surface of the article, and the diameter may be smaller than the length. The article may be any suitable device such as, but not limited to, a tubular stir shaft that may have stirring element(s) extending outwardly therefrom.
In another embodiment related to an apparatus for being in contact with molten glass, the apparatus may comprise an article having an outer surface for being in face-to-face contact with the molten glass, and a conditioning unit in fluid communication with an interior space of the article, for causing fluid to flow within the interior space, wherein the fluid is for restricting any inward hydrogen permeation through a wall of the article. The article may be any suitable device such as, but not limited to, a tubular stir shaft that may have stirring element(s) extending outwardly therefrom.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.
The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.
Various embodiments will now be described more fully with reference to the accompanying drawings. The same reference numerals may be used throughout the drawings to refer to the same or like parts. However, aspects may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
The stirring chamber 10 may include an inlet 12 and outlet 14 by way of which the interior of the stirring chamber may be in fluid communication with the finer tube and the delivery vessel, respectively. Glass sheets may be made in the glass manufacturing system, for example in the manner described in U.S. Pat. No. 7,628,038, the entire disclosure of which is incorporated herein by reference. Alternatively, the glass manufacturing system may be configured for forming any other suitable types of glass articles.
One aspect of this disclosure is the provision of methods, systems and apparatus that seek to restrict any hydrogen permeation blistering associated with a noble metal article such as, but not limited to, a tubular stir shaft 18 having an outer surface for being in face-to-face contact with the molten glass 16 being processed within the glass manufacturing system. In this regard and for example, the stir shaft 18 may be part of a stirrer 20 for stirring molten glass 16 being within the interior of the stirring chamber 10. The stirrer 20 may optionally further include one or more stirring elements 22, such as blades or any other suitable features, that may be fixedly connected to and extend outwardly from the lower end of the tubular stir shaft 18 that is submersed in the molten glass 16 within the stirring chamber 10. The molten glass 16 may be formed and supplied to the interior of the stirring chamber 10 in a conventional manner.
In one aspect of this disclosure and as will be discussed in greater detail below, any inward hydrogen permeation from the molten glass 16 through the sidewall of the tubular stir shaft 18 may be restricted by having a predetermined substance (e.g., media) or filling 24 within the interior space of the stir shaft. The predetermined substance may optionally have associated therewith a partial pressure of hydrogen that is at least about the same as the partial pressure of hydrogen associated with the molten glass 16 being stirred within the stirring chamber 10. The predetermined substance may be a solid, liquid or gas, as will be discussed in greater detail below. More specifically and in one example, the partial pressure of hydrogen provided by the filling 24 at the face-to-face contact between the filling and the inner surface of the tubular stir shaft 18 may be at least about the same as any partial pressure of hydrogen provided by the molten glass 16 at the face-to-face contact between the molten glass and the outer surface of the stir shaft, as will be discussed in greater detail below.
As shown in
In the embodiment illustrated in
As shown in
The glass filling 24 in the interior space of the tubular stir shaft 18 is for slowing any permeation of hydrogen inwardly through the wall of the stir shaft 18 by providing a permeation or diffusion barrier. For example, glasses may have a hydrogen permeation rate that is about one hundred times slower than that of platinum. By having the glass filling 24 in opposing fact-to-face contact with the inner surface of the stir shaft 18 and the upper surface of the lower end wall 32, any hydrogen loss from the processed molten glass 16 through the stirrer 20 may be significantly slowed, for reducing or perhaps even eliminating oxygen blister generation proximate the outer surface of the stir shaft.
For example, the glass filling 24 may comprise, consist essentially of, or consist solely of any glass that will be of sufficiently low viscosity to substantially fill the lower length L of the interior space of the tubular stir shaft 18 with minimal void formation. Optionally, the glass filling 24 may have a higher Beta-OH than the molten glass 16 being processed. Beta-OH may be characterized as being a surrogate measure of the amount of water in the glass, which is proportional to the partial pressure of hydrogen in the glass. Stated differently, beta-OH may be characterized being a measure of the hydroxyl content in the glass, which may be measured by infrared spectroscopy. A glass with a higher Beta-OH should have associated therewith a higher partial pressure of hydrogen than a lower Beta-OH glass. By placing a glass with a higher Beta-OH in the interior space of the stir shaft 18, a flux of hydrogen through the wall of the stir shaft and into the molten glass 16 being processed may be established, for suppressing any oxygen blister formation in the molten glass 16 at the outer surface of the stir shaft.
The glass filling 24 may be provided in the interior space of the tubular stir shaft 18 in any suitable manner, such as by putting a cored cylinder of glass in the interior space of the stir shaft 18 as the stirrer 20 is being fabricated. As another example, powdered cullet may be poured inside the interior space of the stir shaft 18 as the stirrer 20 is being fabricated, or the powdered cullet may be poured inside the interior space of the stir shaft after the stirrer is installed, perhaps even while the glass manufacturing system is operating, and the powdered cullet may melt within the interior space of the stir shaft.
In another example, the glass filling 24 may be introduced in situ, wherein there may be one or more holes 40 (e.g., small holes) that extend through the sidewall of the stir shaft 18 for allowing the molten glass 16 being processed to seep or flow through the holes into the interior space of the stir shaft to form the filling 24, so that the molten glass 16 being processed and the glass of the filling 24 are the same (e.g., substantially similar). In this regard, examples of such holes 40 extending through the wall of the stir shaft 18 are schematically illustrated by dashed lines in
As an example of a method that may be associated with the embodiment shown in
The glass filling 24 may be thicker than a wall thickness defined between the inner and outer surfaces of the tubular stir shaft 18. The glass may extend substantially continuously across the diameter D of the lower length L of the stir shaft's interior space, from one of the diametrically opposite portions of the inner surface of the stir shaft 18 to the other of the diametrically opposite portions of the inner surface of the stir shaft, and the glass filling may be in face-to-face contact with each of the diametrically opposite portions of the inner surface of the stir shaft. The diameter D of the lower length L of the stir shaft's interior space may be the inner diameter of the stir shaft 18.
The diameter D may be more generally referred to as a maximal crosswise dimension. For example, whereas the tubular stir shaft 18 may be a cylindrical tube, the tubular stir shaft may be in other suitable configurations such as, but not limited to, in the form of triangular or other suitably shaped tubes.
In accordance with one aspect of this disclosure, the glass filling 24 may fill the entire volume (e.g., substantially the entire volume) of the lower length L of the stir shaft's interior space that extends from the lower end wall 32 to the upper surface 34 of the glass filling, so that only (e.g., substantially only) glass of the glass filling is present in the lower length L of the stir shaft's interior space that extends from the lower end wall 32 to the upper surface 34 of the glass filling. In this regard, it may be advantageous to omit refractory materials, such as silicate and/or alumina based ceramic materials (e.g., SiO2 ceramic material), from the interior space of the stir shaft 18 because the glass filling 24 may corrode the refractory materials. Alternatively, the glass filling 24 may fill less than the entire volume of the lower length L of the stir shaft's interior space that extends from the lower end wall 32 to the upper surface 34 of the glass filling. For example, when the glass filling 24 is in the form of cullet that has not yet been melted, there may be voids between adjacent pieces of the cullet and/or the article may be something other than a tubular stir shaft 18, such as, but not limited to, a level probe, bell or bell shaft (e.g., for use in forming glass tubing), thermocouple sheath, or the like. For example, the glass filling 24 may occupy only a portion of the volume of the lower length L of the article or stir shaft's interior space that extends from the lower end wall 32 to the upper surface 34 of the glass filling, such as at least about 33% of that volume, at least about 50% of that volume, at least about 75% of that volume, at least 90% of that volume, at least about 98% of that volume and/or any other suitable amount.
The embodiment illustrated in
In accordance with the embodiment illustrated in
Referring to
Referring to
The coupler 152 may be in the form of a downwardly open chamber, so that the coupler includes a lower opening. The lower opening of the coupler 152 may be open to the upper end of tubular stir shaft 118, so that there is open fluid communication between the interior space of the stir shaft and the interior space of the coupler. The coupler 152 may include, have connected thereto, or otherwise be associated with one or more passageways 158, 160, 162 (e.g., tubes or other suitable conduits) of the control system 150. For example, an upstream passageway 158 may be connected between the coupler 152 and a conditioning unit 164 of the control system 150, for providing fluid communication between the interior space of the coupler and the conditioning unit. The conditioning unit 164 may include or be associated with one or more motor-driven pumps 166 (e.g., fan(s)) for moving the circulated liquid (e.g., gas) through the control system 150 and the interior space of the stir shaft 118. The pump 166 may be mounted to or otherwise in fluid communication with the conditioning unit 164. An intermediate passageway 160 may be connected between the pump 166 and the coupler 152, and a downstream passageway 162 may be connected to the intermediate passageway for providing fluid communication between the pump and a lower portion of the interior space of the stir shaft 118. That is, the downstream passageway 162 may extend downwardly into the interior space of the stir shaft 118. More specifically, the downstream passageway 162 may extend coaxially downwardly into the interior space of the stir shaft 118, and the outer diameter of the downstream passageway 162 may be smaller than the inner diameter D of the tubular stir shaft 118.
As schematically partially shown by the series of arrows in
As one example, the conditioning unit 164 may be or may include a humidifier. As another example, the conditioning unit 164 may include a variety of features that may be variously arranged within the control system 150. For example, the control system 150 may provide (e.g., circulate) a humid, low oxygen atmosphere within the interior space of the stir shaft 118. In this regard, the conditioning unit 164 may provide a mixture of water vapor, oxygen and nitrogen (or another inert gas like argon or helium). In this regard, the closed-loop control system 150 may include a computerized controller that obtains sensor readings from one or more locations within the control system. The sensors may include one or more of each of a flow sensor, dew point/humidity sensor, temperature sensor, oxygen sensor, and pressure sensor. The computerized controller may processes the sensor measurements and control different features of the conditioning unit 164, such as a humidity feed system, a heating/cooling control system, the pump(s) 166 and an O2/N2 makeup system. The pump(s) 166 may have access to a process gas such as air, steam and/or any other suitable material. In operation, the computerized controller, or the like, controls the devices of the closed loop control system 150 to create an environment/atmosphere inside the interior space of the stir shaft 118 that has a partial pressure of hydrogen that is at least about the same as, or greater than, the partial pressure of hydrogen associated with the molten glass 116 being stirred within the stirring chamber 110. The control system 150 may include suitable features and operations described in U.S. Pat. No. 7,628,038, the entire disclosure of which has already been incorporated herein by reference.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.
It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents.
