System and method for controlling the environment around one or more vessels in a glass manufacturing system

Abstract

A system and method are described herein that control the environment (e.g., oxygen, hydrogen, humidity, temperature, gas flow rate, pressure) around one or more vessels in a glass manufacturing system. In the preferred embodiment, the system includes a closed-loop control system and a capsule that are used to control the level of hydrogen around the exterior (non glass contact surface) of the vessel(s) so as to suppress the formation of gaseous inclusions and surface blisters in glass sheets. In addition, the closed-loop control system and capsule can be used to help cool molten glass while the molten glass travels from one vessel to another vessel in the glass manufacturing system. Moreover, the closed-loop control system and capsule can be used to maintain an atmosphere with minimal oxygen around the vessel(s) so as to reduce the oxidation of precious metals on the vessel(s).

1 . A method for producing a glass product, said method comprising the steps of: 
 forming/processing molten glass within a melting, a fining, a delivery, and a forming vessel;    enclosing at least one of the vessels; and    monitoring/controlling an atmosphere around a non-glass contact surface of said at least one vessel, wherein said step of monitoring/controlling further includes: 
 controlling a level of hydrogen within a mixture of gases in the atmosphere so that a partial pressure is maintained at or greater than a level defined by an equilibrium relationship pH 2  (ppm)=78,000×eˆ [(−58,900+13.1 T)/(1.987*T(° K.))]  around the non-glass contact surface of said at least one vessel to prevent or mitigate oxidation reactions like hydrogen permeation and electrochemical reactions from occurring in the molten glass thus effectively suppressing the formation of undesirable gaseous inclusions within the molten glass.  
   
     
     
         2 . The method of  claim 1 , wherein said monitoring/controlling step further includes the step of controlling a level of oxygen within the gas mixture around the non-glass contact surface of said at least one vessel to reduce oxidation of a precious metal on said at least one vessel.  
     
     
         3 . The method of  claim 1 , wherein said monitoring/controlling step further includes the step of controlling a cooling of the molten glass while the molten glass travels from one of said at least one vessel to another one of said at least one vessel.  
     
     
         4 . The method of  claim 1 , wherein said gas mixture results in up to 38,000 ppm of hydrogen at the non-glass contact surface of said at least one vessel.  
     
     
         5 . The method of  claim 1 , wherein said gas mixture is maintained at a dew point temperature of 200° F. or lower.  
     
     
         6 . The method of  claim 1 , wherein said gas mixture has an oxygen content with a level of less than 21% by volume.  
     
     
         7 . The method of  claim 1 , wherein said gas mixture has an oxygen level of 0.01% to 1% by volume and a water vapor level of 2% to 20% by volume, with the balance being essentially an inert gas.  
     
     
         8 . The method of  claim 1 , wherein said gas mixture includes cracked ammonia products or combustion products.  
     
     
         9 . The method of  claim 1 , wherein said non-glass contact surface of said at least one vessel includes a metal selected from gold, platinum, rhodium, iridium, molybdenum, palladium, rhenium, tantalum, titanium, tungsten and alloys thereof.  
     
     
         10 . A glass manufacturing system comprising: 
 a melting, fining, delivery, and forming vessel, each vessel includes an inner wall which contacts molten glass;    a capsule that encloses at least one of the vessels;    a closed-loop control system that monitors and controls an environment within said capsule and around a non-glass contact surface of said at least one vessel; and    wherein said closed-loop control system controls a level of hydrogen within a mixture of gases in the environment so that a partial pressure is maintained at or greater than a level defined by an equilibrium relationship pH 2  (ppm)=78,000×eˆ [(−58,900+13.1 T)/(1.987*T(° K.))]  around the non-glass contact surface of said at least one vessel to effectively suppress formation of undesirable gaseous inclusions within the molten glass.    
     
     
         11 . The glass manufacturing system of  claim 10 , wherein said closed-loop control system further controls a level of oxygen within the gas mixture in the environment around the non-glass contact surface of said at least one vessel to reduce oxidation of a precious metal on said at least one vessel.  
     
     
         12 . The glass manufacturing system of  claim 10 , wherein said closed-loop control system further controls a cooling of the molten glass while the molten glass travels from one of said at least one vessel to another one of said at least one vessel.  
     
     
         13 . The glass manufacturing system of  claim 10 , wherein said gas mixture includes up to 38,000 ppm of hydrogen at the non-glass contact surface of said at least one vessel.  
     
     
         14 . The glass manufacturing system of  claim 10 , wherein said gas mixture is maintained at a dew point temperature of 200° F. or lower.  
     
     
         15 . The glass manufacturing system of  claim 10 , wherein said gas mixture has an oxygen content with a level of less than 21% by volume.  
     
     
         16 . The glass manufacturing system of  claim 10 , wherein said gas mixture has an oxygen level of 0.01% to 1% by volume and a water vapor level of 2% to 20% by volume, with the balance being essentially an inert gas.  
     
     
         17 . The glass manufacturing system of  claim 10 , wherein said gas mixture includes cracked ammonia products or combustion products.  
     
     
         18 . The glass manufacturing system of  claim 10 , wherein said non-glass contact surface of said at least one vessel includes a metal selected from gold, platinum, rhodium, iridium, molybdenum, palladium, rhenium, tantalum, titanium, tungsten and alloys thereof.  
     
     
         19 . A system for controlling an environment around at least one vessel in a glass manufacturing system, said system comprising: 
 a capsule that encloses said at least one vessel;    a closed-loop control system that controls a level of hydrogen within a mixture of gases located within said capsule so that a partial pressure is maintained at or greater than a level defined by an equilibrium relationship pH 2  (ppm)=78,000×eˆ [(−58,900+13.1 T)/(1.987*T(° K.))]  around a non-glass contact surface of said at least one vessel to effectively suppress formation of undesirable gaseous inclusions within the molten glass located within said at least one vessel.    
     
     
         20 . The system of  claim 19 , wherein said closed-loop control system further controls a level of oxygen within the gas mixture around the non-glass contact surface of said at least one vessel to reduce oxidation of a precious metal on said at least one vessel.  
     
     
         21 . The system of  claim 19 , wherein said closed-loop control system further controls a cooling of the molten glass while the molten glass travels from one of said at least one vessel to another one of said at least one vessel.  
     
     
         22 . The system of  claim 19 , further comprising a constrictor plate positioned around the non-glass contact surface of one of said at least one vessel that reduces a flow of the gas mixture over that vessel and causes a laminar flow of the gas mixture within said capsule.  
     
     
         23 . The system of  claim 19 , wherein said closed-loop control system includes: 
 a controller;    a plurality of sensors;    a humidity feed system;    a heating/cooling control system;    a air handler; and    an O 2 /N 2  makeup system.    
     
     
         24 . A method for producing a glass product, said method comprising the steps of: 
 forming/processing molten glass within a melting, a fining, a delivery, and a forming vessel;    enclosing at least one of the vessels; and    monitoring/controlling an atmosphere around a non-glass contact surface of said at least one vessel, wherein said step of monitoring/controlling further includes: 
 controlling a level of hydrogen within a mixture of gases in the atmosphere around the non-glass contact surface of said at least one vessel to reduce hydrogen permeation from the molten glass and effectively suppress formation of undesirable gaseous inclusions within the molten glass; and  
 controlling a level of oxygen within the gas mixture around the non-glass contact surface of said at least one vessel to reduce oxidation of a precious metal on said at least one vessel.  
   
     
     
         25 . The method of  claim 24 , wherein said step of monitoring/controlling further includes controlling a flow rate and heat of the gas mixture around the non-glass contact surface of said at least one vessel.