Ppg Industries, Inc.

Yih-Wan Tsai

John E Sensi

George A Pecoraro

John F Krumwiede

Robert Gagne

Jeffrey S Yigdall

Vincent I Henry

Walter W Scott

Robert H Duffus

A method of controlling NO.sub.x emissions from a glass melting process in which combustion fuel produces exhaust gas in a melting furnace including NO.sub.x compounds is disclosed. Furnace exhaust gas passes from the melting furnace through a regenerator to a zone downstream from the regenerator. Ammonia is injected into the furnace exhaust gas at the downstream zone while the furnace exhaust gas is within a desired temperature range to reduce the amount of NO.sub.x compounds. Additional gas is introduced into the furnace exhaust gas as it moves from the regenerator to the downstream zone whenever the furnace exhaust gas has a temperature which is outside the desired temperature range at the downstream zone so as to modify the furnace exhaust gas temperature such that the furnace exhaust gas is within the desired temperature range when furnace exhaust gas reaches to the downstream zone. In one particular embodiment of the invention, the additional gas is the exhaust from an excess air burner which is injected into the furnace exhaust gas at a temperature such that the furnace exhaust gas and the injected gas have a combined temperature between about 870 to 1090.degree. C. at the downstream zone.

Reduction of NO.sub.x emissions in a glass melting furnace

The instant invention provides a method of controlling the accumulation of sodium sulfate in the checker packing of a regenerator of a cross-fired regenerative-type glass melting furnace. Typically, glass batch materials are melted within the furnace by combustion of fuel. This combustion produces exhaust gas that is drawn through the regenerator and heats the checker packing. During the melting operation, sodium sulfate gas is formed by the melted glass and is carried with the exhaust gas through the regenerator. The sodium sulfate gas may condense on a portion of the checker packing. As the sodium sulfate condensate accumulates on the checker packing, it may restrict the flow of exhaust gas and/or combustion air through the regenerator. In the instant invention, a section of the regenerator which includes the portion of the checker packing with the condensed sodium sulfate is selectively heated to a temperature sufficient to melt the sodium sulfate, while any additional heating of remaining sections of the regenerator is minimized. In one embodiment of the invention, fuel is injected into a portion of the exhaust gas that passes through the section of the regenerator where the sodium sulfate condensate has accumulated. The fuel burns with the portion of the exhaust gas and heats the portion of the checker packing with the sodium sulfate build-up to melt the sodium sulfate.

Method of controlling accumulation of sodium sulfate on the checker

The present invention provides an apparatus and method for reducing the occurrences of solid defects in float glass due to corrosion of refractory in a glass melting and refining furnace. In making flat glass by the float process, batch materials are fed into a melting and refining furnace and heated to form molten glass. The molten glass passes through the melting section and into a refining section of the furnace where the glass is gradually cooled and conditioned prior to delivering the glass to a forming chamber where the molten glass is floated upon molten metal and formed into a continuous sheet of glass. During the melting operation, alkali vapors from the molten glass accumulate within a downstream portion of the melting section. These vapors attack and corrode those portions of the melting section of the furnace which are constructed from silica refractory. The products of the corrosion are deposited in the molten glass resulting in solid defects. In the present invention, a nonreactive gas is directed into the downstream portion of the melting section at a temperature no greater than that of the molten glass within the melting section and at a gas volume sufficient to reduce the amount of alkali vapors in the downstream portion of the melting section. As a result, the corrosion of the silica refractory is reduced and the total occurrences of solid defects in the glass due to refractory corrosion is reduced. In one embodiment of the invention, the gas is the combustion products from burners that are positioned in the downstream portion of the melting section of the furnace.

Reduction of solid defects in glass due to refractory corrosion in a

In a method of making glass or the like, wherein the batch materials are liquefied in a distinct zone from the refiner, the liquefied material is heated in an intermediate stage before being fed to the refiner. The heating entails intensified flames that impinge the surface to provide homogenization and a barrier to surface flow of low density material.

Heating and agitating method for multi-stage melting and refining of

A multi-outlet burner for heating material. Nozzles are positioned along a longitudinally extending portion of the burner that generally parallels the material surface. Combustion gas and fuel are combined at each nozzle to produce a plurality of flames that are directed in a sweeping direction over the surface.

Burner design for melting glass batch and the like

The circulation of exhaust gas within a heating vessel is controlled to reduce the adverse effects of the abrasive and corrosive exhaust gas on exposed interior surfaces of the vessel. The firing rates of the burners in the vessel may be varied to alter the flow patterns within the vessel. Additional jet burners with high exhaust gas velocity may be used to direct their exhaust flow in a direction opposing the exhaust flow of other selected burners. Burners may also be angled so as to reduce the flow component of the exhaust gas that may pass over the exposed interior surfaces of the vessel.

Glass melting in a rotary melter

Exhaust from a melting vessel passes through a transition section and into a rotary kiln to preheat batch material. A gas jet injects a high velocity gas stream into the transition section to alter its flow and reduce buildup of material due to entrained material in the exhaust leaving sticky deposits on interior surfaces of the transition section and kiln.

Reduction of material buildup by means of gas jet

In a heating vessel wherein corrosive exhaust degrades exposed positions of the vessel, a high velocity gas jet injects gas between the corrosive exhaust and the exposed portions of the vessel. The gas minimizes contact between the exhaust and the exposed portions so as to reduce wear due to corrosive degradation.

Method and apparatus for furnace lid purging

A burner tip for passing fuel into a glass melting chamber, the burner tip having at least a portion thereof extending a distance into a fuel input passageway fluidly communicating the chamber interior to the chamber exterior, the distance being sufficient to minimize inspiration of chamber exterior or ambient air through an unsealed space formed between the outside surface of the burner tip and the walls forming the fuel input passageway, into the chamber interior, wherein at least the portion of the burner tip which extends into the fuel input passageway is made of high temperature, high oxidation-resistant material capable of withstanding the chamber interior atmosphere during both firing and off-firing cycles, while in direct contact therewith over a substantial time period. The input passageway-extending portion of the burner tip can be precoated with an inhibitor coating to minimize resistant material volitilization and to minimize reactions between the resistant material and refractory materials, especially refractory cement which may be employed to seal the unsealed space.

Energy efficient and anti-corrosive burner nozzle construction and

Regenerator packing members are constructed and arranged to form tapered passageways interconnecting regenerator flues to induce transverse flow of gas between flues for increased heat transfer. A preferred embodiment includes parallelepiped bricks arranged in an open basketweave pattern, with spaces between brick ends and side faces defining the tapered passageways.

Regenerator checker packing with enhanced transverse flow

In a regenerative furnace of the type used for melting glass, localized overheating of the regenerator packing is minimized, heating of the regenerator packing is made more uniform, and regenerator efficiency is improved by employing flow control gas jets in the space alongside the regenerator packing to counteract flow imbalances in the regenerator.

Regenerator flow distribution by means of upstream and downstream air

A method of and apparatus for selective control of combustion gas flow in a furnace firing port in a furnace of the type having a plurality of firing ports, each port having a passageway for receiving combustion gas, e.g. preheated air, from a common plenum chamber, wherein the chamber includes a back or target wall in opposed spaced relationship to each of the passageways. A flow control pipe is inserted through a plenum wall directed toward the passageway between the plenum and port. A small quantity of pressurized gas, e.g. air, is injected generally along the flow path of combustion air in the plenum toward passageway to alter the amount of combustion air flowing into the port. In a preferred embodiment, combustion air is increased by injecting air through a target wall flow control pipe cocurrent with the flow to induce additional flow into the port and combustion air is decreased by injecting air countercurrent to the flow adjacent to the passageway to impede flow into the port.

Target wall air jet for controlling combustion air

In a regenerative furnace of the type used for melting glass, localized overheating of the regenerating regenerator packing is minimized and heating of the regenerator packing is made more uniform by the utilization of a manifold flue. The gas distribution space is in continuous contact with the regenerator packing while the manifold flue is joined to said gas distribution space at a plurality of points below the regenerative packing. Further, flow control dampers may be located in the flue between the regenerative packing and the joining point of the manifold flue and another damper may be in the manifold flue itself to regulate the passage of gas to and from the regenerative packing so that the packing is evenly heated or cooled.

Manifold regeneration flues for regenerative furnaces

In a regenerative furnace of the type used for melting glass, localized overheating of the regenerating regenerator packing is minimized and heating of the regenerator packing is made more uniform by the utilization of a second flue. The first flue passage is in continuous contact with the regenerative packing while the second passage is joined to said first passage at points at each end of the regenerative packing. Further, there are flow control dampers located in said first passageway between the regenerative packing and the joining point of the second bypass flue and another damper in the bypass flue itself to regulate the passage of hot gas to and from the regenerative packing so that the packing is evenly heated or cooled.

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Pittsburgh, PA, United States of America

Yih-Wan Tsai