JP2002071276A - Tunnel type continuous moisture-containing gas atmosphere burning furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for constantly adjusting and observing the flow rate of gas containing moisture for each branch by largely dividing a throwing gas path into degreasing, burning, reoxidation, and the like so that the constituent of gas containing moisture in the furnace forms a specific concentration distribution along a direction for carrying an object to be treated and further providing a proper number of branches for each zone in a tunnel type continuous moisture-containing gas atmosphere burning furnace. SOLUTION: A piece of moisture-containing equipment is provided to each zone of degreasing, burning, reoxidation, and the like along the direction of transport in the furnace for supplying a specific gas constituent containing moisture to each zone, and further a required number of branches are provided to each zone, a flowmeter for constantly setting and observing the flow rate of gas containing moisture can be fitted to each branch, and a specific amount of gas containing moisture is dispersed and thrown into a plurality of locations in the furnace, thus making uniform the concentration of the gas constituent containing moisture in each zone, or forming a specific concentration distribution, and hence easily achieving desirable atmospheric conditions in terms of quality of the object to be treated. Also, as the flowmeter that is constantly capable of setting and observing the flow rate of the gas containing moisture, the flowmeter is provided with countermeasures against dew formation where, for example, a heater for increasing temperature, a temperature detection means, and a temperature control means are combined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel type continuous atmosphere firing furnace which is mainly used for firing functional electronic ceramic elements and the like and requires the injection of a humidified gas in order to bring out the functionality of the element. It is.

[0002]

2. Description of the Related Art In recent years, in the firing of some functional ceramics, it has been necessary to change the atmosphere in the furnace with time simultaneously with firing conditions such as degreasing → firing → reoxidation in the firing process. . When this is performed in a tunnel type continuous furnace, a predetermined amount of a gas of a component corresponding to each area is injected into the furnace in order to form a predetermined atmosphere in each area along a workpiece transfer path in the furnace. are doing. Furthermore, in order to maintain the atmosphere inside each region uniformly at a predetermined atmosphere, the input gas is usually branched into a plurality of locations and injected from the plurality of locations, and the flow rate of the gas for each branch is measured by a flow meter or the like. Adjusting and monitoring. This method has been carried out without any problem when the input gas does not contain moisture, and has achieved a predetermined purpose. Accordingly, in recent years, it has become necessary to perform calcination in a humid atmosphere, and it is also necessary to finely change the partial pressure of water vapor for each region in the furnace. However, there is a problem in performing such a wet gas injection by the above method. This is because in the case of a humidified gas, dew condensation occurs in the tapered pipe of the flow meter, and moisture accumulates inside.
In order to avoid this problem, the flow measurement may be replaced by measuring the flow rate of the non-humidified gas before passing through the humidifier, but the correct flow rate of the humidified gas cannot be obtained. Since the flow rate of each branch provided for uniform charging in the furnace after the humidifier cannot be confirmed, the original purpose of branch charging has not been achieved. Therefore, if the flow rate of each branch is absolutely necessary, install a bypass pipe in each flow meter, always pass the wet gas through the bypass pipe, and flow the wet gas for a short time only when flow rate adjustment and confirmation are necessary. Take measures such as passing through a meter. However, in this case, too, only intermittent measurement can be performed, and the measurement procedure is complicated.In addition, the piping is complicated on the equipment, and it is necessary to secure space for the bypass system. There were many negative factors on costs, such as an increase in man-hours.

[0003]

SUMMARY OF THE INVENTION According to the present invention, in a tunnel-type continuous humidified gas atmosphere firing furnace, the flow rate of each humidified gas to be branched and injected into the furnace can be correctly set to a predetermined value, and it is possible to constantly set the flow rate. It is an object of the present invention to provide a humidified gas atmosphere sintering furnace that can be continuously monitored, and more specifically, to a humidified gas atmosphere sintering furnace equipped with a flow meter group that has a dew condensation countermeasure at each humidified gas input point. .

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventors have conducted intensive studies and have reached the following conclusions.
Usually, in such a sintering furnace, processes such as degreasing, sintering (reduction), and re-oxidation (cooling) are sequentially performed, so that a substantially constant atmosphere is formed in each process, that is, in each region in the furnace. . Therefore, one moisture humidifier is provided for each region to adjust the moisture content of the atmospheric gas, and when the gas is introduced into the furnace, it is necessary to achieve uniformity of the gas concentration distribution in the corresponding region or conscious concentration. In gradient formation or the like, the flow is branched and injected into a plurality of locations so as to reach a target level, and the flow rate of each is adjusted. The charging points are provided at substantially equal intervals in the furnace length direction on both left and right side walls in each region, but may also be provided at the center of the ceiling. Here, each flow meter is provided with a measure capable of setting or measuring the flow rate of the humidified gas at all times.

[0005]

FIG. 1 is a schematic diagram of a firing furnace according to the present invention and a flow diagram of a gas line, and a thick arrow indicates a direction in which a processed material is conveyed in the furnace. A degreasing zone, a firing (reduction) zone, and a re-oxidation (cooling) zone are formed in the furnace in order from the left to the right in the figure, and one moisture impregnator is provided for each zone. Is prepared. Also, the inside of each zone is provided with a branch on the downstream side of the humidifier so that the atmosphere gas of a predetermined component composition is uniformly filled or a predetermined concentration gradient is formed. Then, the wet gas is introduced into the furnace through a plurality of introduction holes provided at substantially equal intervals along the transport direction. In FIG. 1, the fact that the length of the final arrow of the branched gas line varies in the figure indicates that the gas injection point is on the right and left of the furnace body or on the upper part. In FIG. 1, each flow meter has taken the above measures. On the other hand, FIG. 2 shows a firing furnace provided with a flow meter in front of a conventional wet device. In this method, it is impossible to measure the flow rate of the humidified gas, and the operation is performed with the flow rate of each charging point unknown, so that it is very difficult to form a predetermined atmosphere. FIG. 3 shows a flow line provided with a bypass line in each flow meter, and the input gas is always passed through the bypass line. Are taken out and compared. In this method, if necessary, switch to the flow meter line for a short time,
Although the flow rate can be adjusted and observed, it is troublesome, and a constant flow rate observation is impossible. In addition, the equipment is complicated, which requires additional equipment costs such as extra piping parts and piping work, and makes it difficult to secure an installation space. As a flow meter that can always set or measure the flow rate of the humidified gas that can be used in the present invention, a flow meter that takes measures against dew condensation as described below sufficiently achieves the target. That is, a heater or a heating wire for heating the tapered tube portion of the flow meter so as not to cause dew condensation, and a temperature detecting means such as a thermocouple for monitoring the temperature in a heated state are provided at appropriate positions of the flow meter. By attaching them and combining them with temperature control means such as a temperature controller, the temperature of the tapered tube can be maintained at an appropriate value, and dew condensation inside can be prevented. The mounting location of the heater and the like is desirably on the outside of the taper pipe of the flow meter. However, if this is not possible, the outer shell of the flow meter may be used. By using such a means, the temperature of the humidified gas can be maintained at a predetermined value, so that there is no problem of automatic flow rate fluctuation due to various temperatures as in the conventional method, and it is steady and constant. There is also a great advantage that the correct gas flow rate can be grasped as a whole. In addition, a heater having self-temperature controllability can be used as the heater. By using a heater having an appropriate control temperature value and combining this with a temperature detecting means, it becomes unnecessary to provide a temperature control means. It is also possible to achieve the purpose. Here, it is better to provide the temperature detecting means in order to take appropriate measures when an abnormality occurs.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The following measures were taken for the flow meter in the line shown in FIG. That is, a heating heater such as a tape heater 27 or a rubber heater 22 is attached to the outside of the tapered tube 21 as shown in FIG. Was adhered to the tapered tube 21 in close contact. If these heaters cannot be mounted outside the tapered tube 21,
As shown in FIG. 6, it was attached to the outer shell of the flow meter. In any method, it is indispensable to wind the heat insulating material 23 around the outer shell of the flow meter in order to maintain the heating effect and temperature. FIG. 4 shows an example in which a rubber heater 22 is attached to a tapered tube 21 of a flow meter. A rubber heater 22 is wound around the tapered tube 21 so that the scale and the float can be seen. Furthermore, a thermocouple 26 for temperature detection is attached to the tapered tube 21, a flow meter protection cover 24 is attached, and a heat insulating material 23 is wound thereon. At this time, similarly, the heat insulating material 23 cuts a part of the front surface of the flow meter, and an acrylic plate 25 is attached to the part so that the flow meter can be seen so that the scale and the float of the flow meter can be seen. It also has the role of maintaining the heat retention effect. When it is impossible to attach the rubber heater as shown in FIG. 4, means such as attaching the tape heater 27 to the outer shell of the flow meter as shown in FIG. 6 is executed.
Also in this case, it is necessary to wrap the entire flow meter with the heat insulating material 23 to easily maintain the temperature. In any case, the inside of the tapered tube 21 could be kept above the dew point by combining a temperature controller with a heating means such as a heater and a temperature detecting means such as a thermocouple, thereby preventing dew condensation. In addition, when the occurrence of water droplets due to dew condensation was observed during operation for some reason, the water droplet generation phenomenon was eliminated by setting the heater control temperature higher.

[0007]

As described above, the tunnel-type continuous humid gas atmosphere calcination characterized by the method of branching in the humid gas according to the present invention and the installation of the flow meter group with special measures against dew condensation in each branch line. In the furnace, the adjustment and measurement of the flow rate of the humidified gas can be performed at all times, and accurate control and adjustment of the atmosphere in the furnace became easy. Therefore, it greatly contributes to improving the quality of the fired product. Furthermore, the bypass pipe which has been conventionally used for intermittent measurement of the flow rate of the humidified gas is not required, so that effects such as space saving, parts saving, and reduction in the number of construction steps are obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a tunnel-type continuous wet gas atmosphere firing furnace of the present invention and a flow diagram of a wet gas line.

FIG. 2 is a piping flow diagram of a flow meter part of the present invention.

FIG. 3 is a side sectional view showing an embodiment of a countermeasure against dew condensation of the flow meter according to the present invention.

FIG. 4 is a plan sectional view of FIG. 3;

FIG. 5 is a side sectional view showing another embodiment of a countermeasure for preventing dew condensation of the flow meter of the present invention.

FIG. 6 is a plan sectional view of FIG. 5;

FIG. 7 is a schematic view of a conventional tunnel type continuous wet gas atmosphere firing furnace and a flow diagram of a wet gas line.

FIG. 8 is a piping flow diagram of a conventional flow meter part.

[Explanation of symbols]

 1. 1. Moisturizer 2. Flow meter (for wet gas) 3. Flow meter (non-humidified gas compatible type) Flow control valve 5. 5. A valve for adjusting the flow rate of the moisture-containing gas in the furnace 6. Gas input line on the front side of the furnace 7. Gas line on the back side of furnace Furnace ceiling charging gas line 21. Tapered tube 22. Rubber heater 23. Insulation material 24. Flow meter protection cover 25. Acrylic plate 26. Thermocouple 27. Tape heater 28. Firing furnace A. Degreasing zone B. B. Firing (reduction) zone Reoxidation (cooling) zone

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F27D 7/06 F27D 21/00 A 21/00 C04B 35/64 A

Claims (4)

[Claims] 1. A tunnel-type continuous-atmosphere sintering furnace, provided with a humidifier for adjusting a dew point for each zone having different thermal conditions and atmospheric conditions in the furnace, and further comprising a multi-branch humidifier from each humidifier. Tunnel type continuous type characterized in that the gas flow rate is adjusted to the value set for each branch, and the branch gas is injected into different positions in the furnace while constantly executing the flow rate instruction for each branch. A humidified gas atmosphere firing furnace. 2. The continuous tunnel type as set forth in claim 1, wherein a flow meter for preventing dew condensation is provided in each of the branched wet gas injection lines, so that the flow rate can be monitored at all times. Type humidified gas atmosphere firing furnace. 3. A heater according to claim 2, wherein a heater for heating and a temperature detecting means are mounted on an outer portion of the tapered pipe, or, when mounting on said portion is impossible, these are mounted on an outer shell of the flow meter. The tunnel type continuous humidified gas atmosphere firing furnace according to claim 2, wherein these are combined with temperature control means. 4. The tunnel type continuous humidified gas atmosphere firing furnace according to claim 3, wherein a self-temperature control type heater is used as a heating heater or the like and temperature control means is omitted.