JP2022088071A - Glass melting furnace monitoring method and glass article manufacturing method - Google Patents

Abstract

To provide a glass melting furnace monitoring method that makes it possible to detect abnormal heat buildup in a refractory material constituting a glass melting furnace before erosion occurs in the refractory material.SOLUTION: This glass melting furnace monitoring method is for monitoring erosion of a refractory material 111 constituting a glass melting furnace for heating and melting a glass material Gr by using electrodes 14 immersed in molten glass Gm. The present invention comprises a first temperature sensor 151 disposed in an energization region between the electrodes 14, and a second temperature sensor 152 disposed in a non-energization region 18 away from the energization region, and involves detecting abnormal heat buildup in the refractory material 111 by using temperatures measured with the first temperature sensor 151 and the second temperature sensor 152.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method of monitoring abnormal heat generation of a refractory material constituting a glass melting furnace, and a method of manufacturing a glass article using the monitoring method.

Conventionally, the temperature inside the glass melting furnace has been measured for the purpose of stabilizing the operation and improving the efficiency. Patent Document 1 discloses a method of obtaining a temperature profile in a furnace by using a thermograph on the surface of molten glass or a temperature measurement result by a thermocouple inserted in the furnace.

Further, in order to improve the thermal efficiency of the glass melting furnace and suppress the exhaust gas emission amount, a method of heating the molten glass by energizing between the electrodes immersed in the molten glass is used (see, for example, Patent Document 2). ..

Japanese Unexamined Patent Publication No. 2016-22534 Japanese Patent Application Laid-Open No. 2003-183031

The furnace wall and bottom of a glass melting furnace are made of refractory material, and the electric resistance of the refractory material is generally higher than that of molten glass. Current flows through the molten glass.

However, in recent years, glass having various characteristics has been produced, and some of them, such as non-alkali glass, have a higher electrical resistivity in a molten state than conventional glass. When such molten glass is heated by using energization between electrodes, the difference in electrical resistivity between the molten glass and the refractory is smaller than that of conventional glass, and it is easy to energize the refractory. Further, when the refractory is used for a long period of time, the electrical resistivity of the refractory may decrease due to deterioration such as deterioration of the internal structure constituting the refractory. When the electrical resistivity of the refractory decreases relative to the electrical resistivity of the molten glass, the current flowing through the refractory increases and the temperature of the refractory rises. When the temperature of the refractory rises, the electrical resistivity decreases, so the current that flows further increases, and the temperature rises, creating a vicious cycle. As a result, the refractory heat may be abnormally generated and melted, so it is important to detect the abnormal heat generation of the refractory in order to improve the safety and stability of production.

An object of the present invention is to detect an abnormal heat generation in a glass melting furnace before the refractory material constituting the glass melting furnace is melted.

The present invention, which was devised to solve the above problems, is a glass melting furnace monitoring method for monitoring the melting damage of refractories constituting a glass melting furnace in which a glass raw material is heated and melted by using an electrode immersed in molten glass. The first temperature sensor and the second temperature sensor are provided with a first temperature sensor arranged in an energized region between the electrodes and a second temperature sensor arranged in a non-energized region away from the energized region. It is characterized in that abnormal heat generation of the refractory is detected by using the measured temperature of. According to such a configuration, the temperature of the energized region measured by the first temperature sensor is compared with the temperature of the non-energized region measured by the second temperature sensor, and the abnormality due to the energization of the refractory itself in the energized region is compared. The presence or absence of fever can be identified.

In the above configuration, when the measured temperature of the second temperature sensor is subtracted from the measured temperature of the first temperature sensor and the amount of increase in the obtained temperature difference exceeds a predetermined value, the fireproof material is abnormal. It is preferable to detect heat generation. If the refractory does not generate abnormal heat, the temperature of the refractory is determined by the temperature of the molten glass in contact with the refractory. Since the temperature of the molten glass varies depending on the location in the glass melting furnace, the temperature of the refractory also varies depending on the location. By the way, when the operating conditions (input power, etc.) of the glass melting furnace are changed, the temperature of the molten glass changes, but the difference in the amount of temperature change of the molten glass depending on the location is relatively small. Therefore, the difference in the amount of temperature change of the refractory depending on the location is relatively small. Therefore, even if the operating conditions are changed, the temperature difference (comparative temperature difference) obtained by subtracting the temperature measured by the second temperature sensor from the temperature measured by the first temperature sensor becomes close to constant. On the other hand, when the refractory heats up abnormally, the temperature of the refractory is determined by adding the calorific value inside the refractory to the temperature of the molten glass in contact with the refractory. Therefore, regardless of changes in operating conditions, the comparative temperature difference increases by the amount of heat generated inside the refractory. From the above, by monitoring the comparative temperature difference, it is possible to detect abnormal heat generation of the refractory.

In the above configuration, it is preferable that the electrode is arranged on the bottom surface of the glass melting furnace. According to such a configuration, convection of the molten glass can be promoted, a glass article having a uniform composition can be obtained, and molding defects such as striae can be reduced.

In the above configuration, it is preferable that the glass raw material is heated only by energization heating by the electrodes. Compared to the case where the burner and the electrode are used together, when the glass raw material is heated and melted only by the electrode without using the burner, it is necessary to significantly increase the energization of the molten glass, which is an abnormality of the refractory. High risk of fever. Therefore, if the present invention is applied when the glass raw material is heated and melted only by the electrodes without using a burner, the effect of detecting abnormal heat generation of the refractory becomes more remarkable.

In the above configuration, the first temperature sensor and the second temperature sensor are preferably thermocouples. According to such a configuration, the temperature can be easily and accurately measured even if the object to be measured such as a refractory or molten glass constituting the glass melting furnace has a high temperature.

In the above configuration, it is preferable that the temperature measuring units of the first temperature sensor and the second temperature sensor are arranged inside the refractory and measure the temperature of the refractory. The temperature of the refractory in the energized region changes due to the heat transferred from the molten glass and the heat generated by the refractory itself. On the other hand, the temperature of the refractory in the non-energized region changes only by the heat transferred from the molten glass. Therefore, by monitoring the comparative temperature difference, it is possible to detect the temperature change due to heat generation due to the energization of the refractory itself.

In the above configuration, the temperature measuring unit of the first temperature sensor is arranged inside the fireproof material to measure the temperature of the fireproof material, and the temperature measuring unit of the second temperature sensor is the fireproof material and the fireproof material. It is preferably arranged at the boundary with the molten glass and measures the temperature of the molten glass. The difference between the amount of temperature change of the refractory in the non-energized region and the amount of temperature change of the molten glass is small. Therefore, the amount of change in the comparative temperature difference is substantially equal between the case where the second temperature sensor measures the temperature of the refractory and the case where the temperature of the molten glass is measured. Further, for the purpose of controlling the operating conditions of the glass melting furnace, a temperature sensor for measuring the temperature of the molten glass is often installed inside the melting furnace. If the temperature of the molten glass in the non-energized region is measured by using these temperature sensors, it is not necessary to newly install a temperature sensor in the non-energized region.

In the above configuration, it is preferable that the temperature measuring portion of the first temperature sensor and the second temperature sensor is covered with a precious metal cap. With such a configuration, the thermocouple can be protected from the high temperature environment in the vicinity of the molten glass. In addition, since noble metals have higher thermal conductivity than heat-resistant materials such as oxide ceramics, the responsiveness of temperature measurement is improved.

In the above configuration, the melting step of melting the glass raw material by the glass melting furnace using the glass melting furnace monitoring method according to any one of claims 1 to 8 and the melting of the glass melted in the glass melting furnace. It is preferable to include a molding step for molding glass. According to such a configuration, it is possible to manufacture a glass article while monitoring the melting damage of the refractory material constituting the glass melting furnace.

According to the present invention, in a glass melting furnace, it is possible to detect an abnormal heat generation before the refractory material constituting the glass melting furnace is melted.

It is a schematic diagram of the manufacturing method of a glass article. It is a side sectional view of a glass melting furnace. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a cross-sectional view taken along the line BB in FIG. 3 when the temperature measuring unit of the second temperature sensor is located inside the refractory material. FIG. 3 is a sectional view taken along line BB in FIG. 3 when the temperature measuring unit of the second temperature sensor is located at the boundary between the refractory and the molten glass. It is a graph of the simulation result which shows the temperature change of the energized region and the non-energized region when the input power is increased. It is a graph of the simulation result which shows the change of the comparative temperature difference when the input power is increased. It is a graph of the simulation result which shows the temperature change of the energized region and the non-energized region when the alteration of a refractory progresses. It is a graph of the simulation result which shows the change of the comparative temperature difference when the alteration of a refractory progresses.

An embodiment of the glass melting furnace monitoring method according to the present invention will be described.

As shown in FIG. 1, the apparatus for manufacturing a glass article according to the present embodiment includes a melting furnace 1, a clarification tank 2, a homogenization tank 3, a pot 4, a molded body 5, and the like, in order from the upstream side. A supply path 61 to 64 connecting the respective components 1 to 5 of the above is provided. In addition, the manufacturing apparatus includes a slow cooling furnace (not shown) that slowly cools the glass ribbon GR formed by the molded body 5, and a cutting device (not shown) that cuts out a glass plate of a desired size from the strip-shaped glass ribbon GR after slow cooling.

The melting furnace 1 is a container for performing a melting step of melting the charged glass raw material Gr to obtain molten glass Gm, and is connected to the clarification tank 2 by a supply path 61.

The clarification tank 2 is a container for performing a clarification step of defoaming the molten glass Gm supplied from the melting furnace 1 by the action of a clarifying agent or the like, and is connected to the homogenization tank 3 by a supply path 62.

The homogenization tank 3 is a container for stirring the clarified molten glass Gm and performing a homogenization step, and includes a stirrer 31 having a stirring blade. The homogenization tank 3 is connected to the pot 4 by a supply path 63.

The pot 4 is a container for performing a state adjusting step of adjusting the molten glass Gm to a state suitable for molding, and adjusts the viscosity and the flow rate of the molten glass Gm. The pot 4 is connected to the molded body 5 by a supply path 64.

Each supply path 61 to 64 is configured by connecting a plurality of supply pipes made of platinum or a platinum alloy. The outer peripheral surface of each supply path 61 to 64 is held by a refractory material.

In the present embodiment, the molding apparatus for molding the molten glass Gm into a desired shape is configured by the molded body 5. The molded body 5 forms the molten glass Gm into a strip-shaped glass ribbon GR by the overflow down draw method. Specifically, the molded body 5 has a substantially wedge-shaped cross-sectional shape (cross-sectional shape orthogonal to the paper surface of FIG. 1), and an overflow groove (not shown) is formed on the upper portion of the molded body 5.

The molded body 5 causes the molten glass Gm to overflow from the overflow groove and flows down along the side wall surfaces (side surfaces located on the front and back sides of the paper surface) on both sides of the molded body 5. The molded body 5 is formed into a plate shape by fusing the flowed molten glass Gm at the lower top portion of the side wall surface.

Hereinafter, a specific configuration of the melting furnace 1 will be described with reference to FIG. 2.

As shown in FIG. 2, the melting furnace 1 energizes the melting tank main body 11, the screw feeder 12 for supplying the glass raw material Gr, the flue 13 for discharging the gas in the melting furnace 1 to the outside, and the molten glass Gm. It includes an electrode 14 for heating and a temperature sensor 15 for monitoring abnormal heat generation of the refractory material 111.

The melting tank main body 11 melts the glass raw material Gr by energization heating to form the molten glass Gm. The melting tank main body 11 is made of a refractory material 111 (for example, zirconia-based electroformed bricks, alumina-based electroformed bricks, etc.), and forms a section for the melting space in the furnace. A heat insulating material such as a heat insulating brick (not shown) is arranged around the refractory material 111 to improve the heat retaining property of the melting tank main body 11. In the present embodiment, the melting furnace 1 is a single melter having only one melting space of the glass raw material Gr, but may be a multi-melter in which a plurality of melting spaces are connected. Also. The molten glass Gm flows in the X-axis direction.

The melting furnace 1 is provided with a screw feeder 12 as a raw material supply means. The screw feeder 12 sequentially supplies the glass raw material Gr so that a portion not covered by the glass raw material Gr is formed on a part of the liquid surface of the molten glass Gm. That is, the melting furnace 1 is a so-called semi-hot top type. The melting furnace 1 may be a so-called cold top type in which the entire liquid surface of the molten glass Gm is covered with the glass raw material Gr. Further, the raw material supply means may be a pusher, a vibration feeder, or the like.

The melting furnace 1 is provided with a flue 13 as a gas discharge path for discharging the gas in the melting furnace 1 to the outside. A fan 131 for sending gas to the outside is provided in the flue 13. The fan 131 may not be provided.

The refractory material 111 of the melting furnace 1 is provided with a plurality of electrodes 14 in a state of being immersed in the molten glass Gm for energization heating. In the present embodiment, the melting furnace 1 is not provided with a heating means other than the electrode 14 provided at the bottom of the furnace. By heating the molten glass Gm only by energizing the electrode 14, the glass raw material Gr supplied to the upper surface of the molten glass Gm is indirectly heated and melted. The electrode 14 is formed of, for example, rod-shaped molybdenum and is supported by the electrode holder 141. The electrode holder 141 includes a cooling pipe (not shown) inside. The cooling pipe cools the electrode 14 and the electrode holder 141 by circulating a liquid cooling material such as water.

The two electrodes 14 surrounded by the alternate long and short dash line in FIG. 3 are paired, and the molten glass Gm is heated by energizing between the electrodes 14 (energized region 16). The region away from the energized region (non-energized region 17) is not energized and heated, but is heated by convection or radiation of the molten glass Gm.

The temperature sensor 15 includes a first temperature sensor 151 and a second temperature sensor 152. The first temperature sensor 151 is arranged in the energized region 16, and the second temperature sensor 152 is arranged in the non-energized region 17. In this embodiment, a thermocouple is used as the temperature sensor 15, but the temperature sensor 15 is not limited to this. A platinum thermometer or a radiation thermometer may be used.

As shown in FIG. 4, the refractory material 111 is provided with a temperature sensor mounting hole 18 for mounting the temperature sensor 15. In the present embodiment, the temperature sensor mounting hole 18 is closed without penetrating the refractory material 111. A precious metal cap 153 is attached to the closed end of the temperature sensor mounting hole 18, and the temperature sensor 15 is pressed against and fixed to the precious metal cap 153 while being housed in the protective tube 154. As a result, the temperature measuring unit of the temperature sensor 15 can be protected from the high temperature environment. In addition, since the precious metal cap 153 has a high thermal conductivity, the temperature of the refractory 111 can be accurately measured. In the present embodiment, the precious metal cap 153 is made of platinum, but the present invention is not limited to this. Platinum alloys, iridium and other highly heat resistant materials may be used.

As shown in FIG. 5, the temperature sensor mounting hole 18 located in the non-energized region 17 may penetrate the refractory material 111. In this case, the precious metal cap 153 comes into direct contact with the molten glass Gm, and the temperature of the molten glass Gm can be measured.

In the non-energized region 17, the temperature of either the molten glass Gm or the refractory 111 may be measured. Although the temperature of the molten glass Gm and the temperature of the refractory material 111 are different, the temperature change due to the change in the operating conditions appears in the molten glass Gm and the refractory material 111 in the same manner. By comparing with the measured temperature of the above, the object of the present invention for detecting the abnormal heat generation of the refractory material 111 can be achieved. Therefore, if the existing second temperature sensor 152 for measuring the temperature of the molten glass Gm or the temperature of the refractory 111 is installed, it is not necessary to newly install the second temperature sensor 152.

Since the refractory 111 is deteriorated due to being exposed to a high temperature environment for a long time, the possibility that the refractory 111 in the vicinity is deteriorated increases as the temperature of the molten glass Gm rises. Further, in the melting furnace 1, the temperature tends to rise toward the downstream side. Therefore, it is preferable to monitor the most downstream energized region 16 where the refractory 111 is likely to deteriorate and generate abnormal heat.

Further, since the electrical resistivity of the glass raw material Gr is higher than that of the molten glass Gm, as the ratio of the glass raw material Gr mixed in the molten glass Gm increases, it becomes easier to energize the refractory material 111 relatively. The risk of abnormal heat generation of the refractory material 111 increases. In the melting furnace 1, since the ratio of the glass raw material Gr mixed in the molten glass Gm increases toward the upstream, it is preferable to monitor the most upstream energized region 16.

The temperature of the refractory 111 that is not energized decreases as it moves away from the molten glass Gm. Therefore, the alteration of the refractory material 111 starts from the boundary surface between the refractory material 111 and the molten glass Gm, and gradually progresses to the inside of the refractory material 111. Therefore, the closer the measurement position by the first temperature sensor 151 is to the molten glass Gm, the earlier the abnormal heat generation of the refractory material 111 can be detected.

The first temperature sensor 151 and the second temperature sensor 152 are connected to a control device (not shown). The control device records the measured temperatures of the first temperature sensor 151 and the second temperature sensor 152, and when the comparative temperature difference exceeds a predetermined value, abnormal heat generation occurs and the risk of melting of the refractory 111 increases. Judge. Hereinafter, the detection of abnormal heat generation will be described using a simulation.

Two pairs of electrodes 14 were arranged inside the melting furnace 1 which was the target of this simulation, and a total of 98.5 kW of electric power was set to be input. Further, as the temperature measured by the first temperature sensor 151, a temperature located between the pair of electrodes 14 and 10 mm from the interface between the refractory 111 and the molten glass Gm on the refractory 111 side was adopted. As the temperature measured by the second temperature sensor 152, the temperature at a position where the height from the bottom surface of the melting furnace 1 is 300 mm and the boundary between the refractory 111 constituting the side surface of the melting furnace 1 and the molten glass Gm is set. Adopted. When reproducing the progress of alteration of the refractory 111 by simulation, the electrical resistivity of the refractory 111 from the boundary surface between the refractory 111 and the molten glass Gm to a predetermined depth (alteration depth) was set low. .. A simulation using the finite volume method was performed according to the above conditions, and the temperature measured by the first temperature sensor 151 and the second temperature sensor 152 was obtained.

FIG. 6 shows the change in temperature measured by the first temperature sensor 151 and the second temperature sensor 152 when the electric power input from the electrode 14 into the melting furnace 1 is increased. The input power is increased from 98.5 kW by 2.5% to 10%. On the other hand, the alteration of the refractory material 111 has not progressed. When the input power is increased, the temperatures measured by the first temperature sensor 151 and the second temperature sensor 152 both increase, and the amount of increase is about the same. Therefore, as shown in FIG. 7, the comparative temperature difference is almost constant regardless of the change in the input power.

FIG. 8 shows the change in temperature measured by the first temperature sensor 151 and the second temperature sensor 152 when the refractory material 111 is deteriorated. The alteration depth of the refractory 111 is increased from 0 mm to 60 mm in increments of 15 mm. On the other hand, the input power is not increased. As the alteration of the refractory material 111 progresses, the temperature measured by the first temperature sensor 151 rises, but the temperature measured by the second temperature sensor 152 hardly changes. Therefore, as shown in FIG. 9, the comparative temperature difference increases as the alteration of the refractory material 111 progresses.

Even if the temperature measured by the first temperature sensor 151 rises, if the temperature measured by the second temperature sensor 152 also rises, it means that the comparative temperature difference has not increased, and the first temperature Since the temperature rise measured by the sensor 151 is caused by fluctuations in operating conditions such as input power, it can be seen that abnormal heat generation does not occur in the refractory material 111. On the other hand, when the temperature measured by the first temperature sensor 151 rises, the temperature measured by the second temperature sensor 152 does not rise, or compared with the temperature rise measured by the second temperature sensor 152. If the temperature rise measured by the first temperature sensor 151 is large, it means that the comparative temperature difference is increasing, and it can be seen that abnormal heat generation is generated in the refractory material 111. Therefore, it is possible to detect whether or not abnormal heat generation is generated in the refractory material 111 depending on the presence or absence of an increase in the comparative temperature difference.

According to the above method, the abnormal heat generation can be detected before the refractory material 111 constituting the glass melting furnace 1 is melted.

The present invention is not limited to the configuration of the above embodiment, and is not limited to the above-mentioned action and effect. The present invention can be modified in various ways without departing from the gist of the present invention.

In the above embodiment, the glass plate is produced by using the overflow downdraw method, but the present invention is not limited to this. The slot down draw method or the float method may be used. Further, in the above embodiment, a glass plate has been described as an example as a glass article, but the present invention is not limited to this. Other glass articles such as glass fiber and tube glass may be manufactured.

In the above embodiment, the electrode 14 is arranged only on the bottom surface of the glass melting furnace 1, but the present invention is not limited to this. The electrode 14 may be arranged on the side surface of the glass melting furnace 1.

In the above embodiment, the molten glass Gm is heated only by heating by energization between the electrodes 14, but heating by a burner may be combined. In this case, the burner is attached to the refractory 111 above the liquid level of the molten glass Gm.

In the above embodiment, the energization between the electrodes 14 uses a single-phase AC power source, but is not limited to this. A three-phase AC power supply may be used. In this case, the three electrodes 14 form a set, and the space between the sets of electrodes 14 forms the energization region 16.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for monitoring a glass melting furnace and manufacturing a glass article using the monitoring method of the glass melting furnace.

1 Melting furnace 111 Refractory 14 Electrode 15 Temperature sensor 151 First temperature sensor 152 Second temperature sensor 153 Noble metal cap 16 Energized area 17 Non-energized area Gm Molten glass Gr Glass raw material

Claims (9)

It is a glass melting furnace monitoring method that monitors the melting damage of refractories constituting a glass melting furnace that heats and melts glass raw materials using electrodes immersed in molten glass.
The first temperature sensor arranged in the energization region between the electrodes and
A second temperature sensor arranged in a non-energized region away from the energized region is provided.
A method for monitoring a glass melting furnace, which comprises detecting abnormal heat generation of a refractory using the measured temperatures of the first temperature sensor and the second temperature sensor. The measured temperature of the second temperature sensor is subtracted from the measured temperature of the first temperature sensor.
The glass melting furnace monitoring method according to claim 1, wherein when the amount of increase in the obtained temperature difference exceeds a predetermined value, abnormal heat generation of the refractory is detected. The method for monitoring a glass melting furnace according to claim 1 or 2, wherein the electrodes are arranged on the bottom surface of the glass melting furnace. The glass melting furnace monitoring method according to any one of claims 1 to 3, wherein the glass raw material is heated only by energization heating by the electrodes. The glass melting furnace monitoring method according to any one of claims 1 to 4, wherein the first temperature sensor and the second temperature sensor are thermocouples. The glass according to any one of claims 1 to 5, wherein the temperature measuring unit of the first temperature sensor and the second temperature sensor is arranged inside the refractory and measures the temperature of the refractory. Melting furnace monitoring method. The temperature measuring unit of the first temperature sensor is arranged inside the refractory and measures the temperature of the refractory.
The glass melting according to any one of claims 1 to 5, wherein the temperature measuring unit of the second temperature sensor is arranged at the boundary between the refractory and the molten glass and measures the temperature of the molten glass. Reactor monitoring method. The glass melting furnace monitoring method according to claim 6 or 7, wherein the temperature measuring unit of the first temperature sensor and the second temperature sensor is covered with a precious metal cap. A melting step of melting the glass raw material by the glass melting furnace using the glass melting furnace monitoring method according to any one of claims 1 to 8.
A method for producing a glass article, which comprises a molding step of molding the molten glass melted in the glass melting furnace.

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