GAS-FIRED HEATING OVEN DEVICE FOR GLASSWORKING THAT HOMOGENIZES THE HEATING OF THE GLASS SHAPE

Abstract

A gas-fired furnace, known as a "heater" furnace for glassmaking, characterized by: - ​​a gas inlet via a funnel-shaped conduit (a), such that the tip (b) of the conduit (a) receives the gas inlet and its base (c) is fixed to the cylindrical wall of the furnace in the upper third (d), - this conduit (a) is also equipped with a flame diffuser (f) placed at the junction of the funnel (a) and the furnace chamber in place of the recess (e) made in the wall, - insulation of the furnace chamber consisting of ceramic insulation placed in a "convex" fold (g), i.e., in successive waves around the entire internal perimeter of the furnace; the resulting folds are placed around the perimeter of the furnace chamber and held in place by compression. Figure for the abbreviated version [Fig. 1]

Description

Title of the invention: GAS HEATING FURNACE DEVICE FOR WORKING GLASS WHICH HOMOGENIZES THE HEATING OF THE GLASS PARISON

[0001] The present invention relates to a gas-fired heating furnace for glassblowers. Compared to known devices, the technologies used to date result in a very high heat loss as soon as the furnace door opens. Let us recall the principle of these furnaces, which are necessary because the glassblower, when blowing into the glass ball, sends air much colder than the heat of the glass. As a result, the ball solidifies quickly, which prevents the glassblower from working. The furnaces are, for the most part, cylindrical in shape for better temperature uniformity in the furnace.

[0002] Several drawbacks reduce the thermal optimization of these furnaces which must maintain a homogeneous temperature. Indeed, while a homogeneous flow circulating around the glass piece would be preferred, known furnaces are equipped with a point jet directed onto the piece, this jet generates turbulence from the point of "impact" of said heating jet. This is due to the fact that the various known devices use a torch principle which directly heats the piece. As a result, the heating jet produces a very localized heating on a small part of the piece, while the rest of the piece reaches variable temperatures due to the turbulence generated by the jet due to random recirculations.

[0003] State of knowledge: We have searched the state of knowledge for existing devices enabling the production of a heating furnace device for working glass which homogenizes the heating of the glass parison and which reduces the energy consumption in work, the heating power being adaptable to the quantity of energy necessary for heating the pieces to be worked.

[0004] State of the art: The state of technological knowledge can be distinguished according to three distinct families:

[0005] a) The first technological family concerns devices for heating parts in furnaces; These devices consist of a torch whose flame comes into contact with the part. These devices are constrained in that: - the flame produces a point heat on the part, - The flame produces a movement of air around the part, which causes a turbulent flow around it, as a result, the heat distribution around the part becomes random.

[0006] We can cite as an example the patent FR673557 which presents a re heater arranged so that the gases are recovered after their journey through the furnace. This furnace allows for even circulation of heat but it does not allow the part to be targeted, so the entire furnace temperature is brought to the same temperature which represents a significant energy expenditure for the parison to reach a desired value. We should also mention the manufacturers OSECO WARWIC, ©CERITHERM, ©NARBETHERM, ©RHODE, ©LINN HIGH THERM, whose technology is based on that described above, and which for the reasons given do not meet our study objective.

[0007] b) - The second technological family concerns a power adjustment device, and devices for regulating furnace temperatures. The existing furnace power adjustment devices are not specific to the operation of heating parisons for glass working, and the known principles cannot be applied to our subject. Indeed, the heating of the glass must be direct and scalable to the size of the piece of glass to be worked, which is not possible with known devices. We can cite the following patents as examples: WO2017112671 presents a furnace whose productivity is increased by modifying the location of the burners in the furnace. This allows a large quantity of glass to be burned while remaining below the desired maximum temperatures. However, this furnace is not suitable for reheating furnaces because it is intended for melting materials to obtain glass and not for reheating the parison. US2014360382 presents a conveyor furnace equipped with a food presence detection system. Depending on the presence or absence of food, the burners change intensity. These devices cannot be used for cane work in reheating glass furnaces because the pieces must be placed on a conveyor passing through the furnace.

[0008] c) - The third technological family concerns the devices for insulating furnaces (to keep the heat in the furnace enclosure). The known devices are not suitable for solving our object because several disadvantages exist: - fibrous materials cannot be thickened because they would eventually collapse in the furnace, - Thermally insulating materials are also electrical insulators which prevent the grounding necessary for starting the heating.

[0009] We can cite as examples the following patents: WO0130710A1 is a method of using sintered tin oxide refractory bricks in the furnace throat (where the glass cools before passing to the refining tank) instead of the usual products. This device is not suitable because it cannot be used in cylinder furnaces. FR1501243A has a wall that insulates the part containing the molten glass and the conditioning compartment of the furnace. A refrigerant flows through this wall, slowing down the hot and cold air currents circulating in the melting compartment, thus saving fuel. This device applies to molten glass baths, not reheating furnaces. FR1287901 is a method for insulating the roof of a furnace, above the melting bath. These devices are not suitable for cylindrical reheating furnaces, as the heating takes place in the center of the cylinder, while in this case the insulation must be perimeter.

[0010] Technological background: EP0867412 shows an insulation system using high-density extruded graphite for an optical fiber drawing furnace. WO9954655 presents furnace insulation using hollow balls. WO2017205882A1 describes a method for insulating an industrial furnace in two layers. The first layer is made of refractory metal and the second is made of carbon. These devices do not concern glass reheating furnaces.

[0011] State of the science: With respect to our subject, which concerns a heating furnace device for working glass which homogenizes the heating of the glass parison and which reduces the energy consumption in work, the heating power being adaptable to the quantity of energy necessary for heating the pieces to be worked, the elements which intervene on the scientific level are: - Turbulent heat flows around the parts are not homogeneous, - Maximum power and instantaneous power are not adjustable, - Insulation thicknesses are limited by collapse under the effect of heat and their mass.

[0012] The bibliographic elements relevant to our subject are given below:

[0013] A first source: “The engineer’s techniques / Ref.: BE9510 VI I Thermal elements of furnaces I This article is from: Archives I by Gérard PANIEZ” is summarized as follows: “Furnaces and ovens are production tools intended to develop or transform materials thanks to thermal transfers between a heat source and the material to be treated. This article describes the equipment and their functions in the first three paragraphs; the fourth emphasizes the energy aspects and the means for understanding or controlling them. The last paragraph specifies the operating methods of these production tools in relation to thermal needs and constraints.”

[0014] A second source: "Engineer Techniques: Ref.: BE8842 VI IFours industriels I This article is from: Energies I Thermique pour l'industrie I by Isidore JACUBOWIEZ", indicates "This article deals with furnaces in their generalities, we try to identify characteristics common to all furnaces". It introduces a series of articles each dealing with furnaces specific to an industry including: furnaces in the steel industry; metal heat treatment furnaces; refining and chemical industry furnaces; cement furnaces; glass industry furnaces; ceramic and refractory product industry furnaces. These texts will cover the specific aspects of each type of furnace.

[0015] A third source: "Engineering techniques: Ref.: BE9510 V2 IThermics of furnaces I This article is from: Energies I Thermal for industry I by Gérard PANIEZ" established that "Furnaces and ovens are found in a large number of industrial sectors but mainly in the metals, materials and ceramics industry. The choice of equipment and functions of furnaces and ovens depends on the applications and the needs of the user. The energy aspects and the modeling with appropriate software allow them to be understood and controlled. The operating modes of these production tools are related to the needs and thermal constraints."

[0016] Again the "Engineering Techniques: Ref.: D832 VI I Very high temperature furnaces. Vacuum furnaces I This article comes from: Archives I by François JACQUES", this article describes the processes for reaching very high temperatures within a furnace, then explains the technologies used in this type of furnace, in particular pressure control, insulation and temperature control methods.

[0017] Other "Engineering Techniques: Ref.: R2380 VI I Explosimeters. Gas Detectors I This article is from: Measurements - Analyses I Physical Measurements I by Antoinette ACCORSI" Summary: "In explosimetry and toxicometry, gas detectors are used in atmospheric monitoring and not in continuous control. Indeed, they are designed to, following a measurement, trigger an alarm when the atmosphere becomes explosive or toxic." This article begins by defining the concepts associated with these devices, in particular the danger thresholds. It then presents the principle of detection of explosimeters and toxicometers, their characteristics and influence quantities, as well as their selection criteria.

[0018] Again the "Engineering Techniques: Ref.: R2752 VI [Temperature measurements in gases and flames - Intrusive measurements and integrated optical measurements I This article is from: Measurements - Analyses I Physical measurements I by Frédéric GRISCH, Pierre GICQUEL, Philippe HERVE", summarizes "The measurement of temperature in gases and flames is certainly the one which, in the complex field of temperature metrology, presents the most difficulties. Temperature measurement techniques have evolved significantly over the last 30 years. In the 1970s-80s, intrusive methods based on probes were still the most used, but then these techniques saw their use decrease with the arrival of non-intrusive optical techniques based on lasers or not. This evolution has allowed the exploration and analysis of reactive environments that have been difficult to access until now.”

[0019] Still the "Engineering Techniques: Ref.: SE5078 VI I Methodologies for installing fixed flammable gas detectors I This article is from: Environment - Safety I Safety and risk management I by Guillaume BREYSSE", Summary: "The fixed detection of flammable gases constitutes one of the ultimate barriers for preventing explosion risks. The positioning of the detectors constitutes a critical element in the effectiveness of the detection system. Although offering a robust design basis, the positioning of detectors based on good engineering practices and operator standards does not allow the effectiveness of the detection system to be demonstrated, which is increasingly required by authorities and operators." This article details the general principles for installing a fixed system of flammable gas detectors and then describes the new methodologies developed in the field of oil and gas.

[0020] “Engineering techniques: Ref.: M3612 VI I Refractory lining of furnaces induction holding furnace for foundry I This article is from: Energies I Thermal for industry I by Jean-Pierre GAUCHE » Summary: “The induction holding furnace, located downstream of the melting station, is the distribution and regulation tank for the liquid metal for the various casting sites of a foundry. The refractory lining of this type of furnace must be resistant to the molten metal alloy and insulating to limit the temperature drop of the liquid metal in the basin. The inductor, the active zone, is the most delicate zone to line because the materials must resist the circulation of the liquid metal. The choice of refractory materials and their implementation are essential for the good life of the lining”.

[0021] “Engineering techniques: Ref.: M3610 V2 IGrefractory lining of furnaces merger for cast iron I This article is from: Materials I Metal forming and foundry I by Jean-Pierre GAUCHE » Summary: « This article describes these new techniques for producing, operating and maintaining refractory linings for the electric induction crucible furnace as well as for the gas rotary furnace. The choice of these linings depending on the melting bed and the metallurgy are also covered in detail.

[0022] Synthesis of the state of knowledge

[0023] Relative to the state of the art, there is no device that is capable of meeting the object of our study. Existing devices are constrained in that:

[0024] Concerning the first technological family cited of devices for heating parts in furnaces; These devices consist of a torch whose flame comes into contact with the part, they present several disadvantages to the object of our study: - the flame of the torch acts in a localized manner on the part while a heating of the whole is preferred. The temperature difference forces the glassmaker to move (in rotation and translation) the piece in front of the torch which remains fixed. Under these conditions, the back and forth movements of the piece in different directions in space give a distribution of the heat which is random. Only the know-how of the glassmaker can compensate for this effect of uncertainty, however this has the disadvantage of prolonged exposure of the piece to the heat, - The flame produces an uncontrolled movement of the hot jet in all directions around the piece, which causes a turbulent flow around it, as a result, the heat distribution around the piece becomes random. This is due to the flame blast which is unique and must be of significant power. This jet produces a random flow around the piece and in the furnace enclosure. The hot air flow can find a flow which is directed towards the furnace door and the glassmaker must also take this phenomenon into account in the reheating operation.

[0025] Concerning the second technological family mentioned, of a power adjustment device, and devices for regulating oven temperatures, the disadvantages are as follows: - There is no adjustment variator according to the dimensions of the pieces to be worked. The pieces placed in the heating furnace are always heated at the same power; the only means of action for the glassmaker is to adjust the exposure time to the flame. This poses a problem, particularly for smaller pieces that must be heated in their entirety in a very short time. For these pieces, either they deform too much because they are exposed for too long, or they are not properly heated. -There are also no known devices for reducing the power when the oven is not in use. This causes unnecessary heat loss since in this case it would be sufficient to simply maintain the volume of the oven enclosure at a certain temperature.

[0026] Concerning the third technological family of insulators mentioned, the known devices are not suitable for solving our object because several drawbacks exist: - fibrous materials cannot be thickened because they would eventually collapse in the furnace. This is due to the fact that the masses of a thick layer of insulation quickly deteriorate and detach from the walls. This effect is increased by the high temperatures in the furnace enclosure, - Thermally insulating materials are also electrical insulators that prevent the grounding required to start the heating. There is a contradiction between the need for grounding to start the torches and the need for insulation that eliminates any part in contact with the me- metal of the oven.

[0027] Relative to the state of science, it is not possible to directly determine a method and a device as desired for the object of study. Indeed, scientific knowledge is constrained in that: - Turbulent heat flows around parts are not homogeneous. This is due to the flows that are in the domain of turbulent combustion around different types of parts. Even if the subjects of turbulent flow are known to scientists, they cannot be determined for our object due to the multitude of dimensions of parts that can be made in the same furnace. This is because each case is particular. -Flexible insulating devices, mandatory in the context of glass reheating furnaces (by impacts on hard surfaces), are limited by their thickness due to the heat conditions and their flexible texture which, in relation to their mass, deforms by gravity and ends up falling.

[0028] The current state of knowledge therefore does not allow us to respond to the object for which our invention attempts to remedy the various drawbacks observed.

[0029] Presentation of the invention: The invention relates to a furnace device powered by gas combustion, a so-called "reheater" furnace for working glass, the purpose of which is to return to an acceptable temperature for working glass, with a view to homogeneity of the temperature of the glass parison. The invention is implemented in a cylindrical furnace whose base is placed on the cylindrical wall, in such a way that the two planes of the cylinder constitute the front and rear walls of the furnace.

[0030] The invention is characterized in that: - the gas is supplied through a funnel-shaped conduit in a pyramid (a), which is placed in an external position of the furnace enclosure, in such a way that the tip (b) of the pyramid (a) receives the gas supply and its base (c) is secured to the cylindrical wall of the furnace in the third of its upper part (d), this wall being hollowed out (e) to the shape and internal dimension of the bottom of the pyramid (c), to allow the passage of the oxidant into the furnace. The purpose of this feature is to provide a wider diffusion of the oxidant inside the chamber, - this conduit (a) is also provided with a flame diffuser (f) placed at the junction of the funnel (a) and the furnace enclosure in place of the recess (e) made in the wall; this flame diffuser (f) is composed of a block of class 28 refractory materials with dimensions between: length 220 and 230 mm, height 110 and 114 mm, depth 60 and 76 mm; while it has several rows of holes which cross the part over its depth. These holes have a diameter between 4 and 5 mm and are spaced 14 mm apart. This specificity has the purpose of both slowing down the flame in the chamber and further amplifying the diffusion of heat, - With regard to the insulation of the furnace enclosure, in order to avoid the acceleration of turbulence due to the flat nature of the insulation, the insulation consists of a ceramic insulation which is placed in a particular way by making so-called "accordion" folds (g), that is to say in successive waves over the entire internal perimeter of the hearth; the insulation in situ has the following specifications: a flexible mineral insulation varying from 12 to 14mm thick, folded back on itself so as to obtain an insulation thickness of 100mm at any point in the furnace enclosure; the folds formed are placed around the perimeter of the furnace enclosure and are held by compression on themselves. This results in a greater thickness of insulation on the furnace wall, which moreover no longer has a flat surface, which imitates turbulence. Brief description of the drawings

[0031] [Fig.l] is a general exploded view of the furnace in the presence of its main characterization, note the positioning of the insulation.

[0032] [Fig.2] is a detailed view of a part of the furnace in the presence of the shaped conduit pyramid funnel (a), flame diffuser (f), and accordion insulation (g) placed in the furnace enclosure.

[0033] Glossary: a) pyramid-shaped funnel-shaped conduit b) tip of the duct c) base of the duct d) securing the conduit to the cylindrical wall of the furnace in a third of its upper part e) the sealing made in the furnace wall f) flame diffuser g) so-called accordion insulation

Claims

[Claim 1] Claims Furnace device powered by gas combustion, so-called “heater” furnace for working glass, characterized by: - a gas inlet which is made by a conduit in the shape of a pyramid funnel (a), conduit placed in a position outside the furnace enclosure, in such a way that the tip (b) of the conduit (a) receives the gas inlet and that its base (c) is secured to the cylindrical wall of the furnace in the third of its upper part (d), this wall being hollowed out (e) to the shape and internal dimension of the bottom of the pyramid (c), to allow the passage of the oxidant into the furnace, - this conduit (a) is also provided with a flame diffuser (f) placed at the junction of the funnel (a) and the furnace enclosure in place of the recess (e) made in the wall; this flame diffuser (f) is composed of a block of class 28 refractory materials with dimensions between: length 220 and 230 mm, height 110 and 114 mm, depth 60 and 76 mm; while it has several rows of holes which cross the part over its depth, these holes having a diameter between 4 and 5 mm and are spaced apart by 14 mm, - insulation of the furnace enclosure which consists of a ceramic insulator placed by making so-called "accordion" folds (g), that is to say in successive waves over the entire internal perimeter of the hearth; the insulation in situ has the following specifications: a flexible mineral insulation varying from 12 to 14mm thick, folded back on itself so as to obtain an insulation thickness of 100mm at any point in the furnace enclosure;the folds formed are placed around the perimeter of the furnace enclosure and are held in place by compression on themselves.;

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