JPH0551335B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention melts metal chlorides (FeCl ₂ , CoCl ₂ ), etc. (hereinafter referred to as heated materials) in order to produce ultrafine powder of metals or metal oxides used in the electrochemical industry. The purpose of this invention is to significantly extend the life of an electric resistance heating type melter-gasifier (hereinafter simply referred to as a melter-gasifier). BACKGROUND ART As shown in FIG. 3, in a melter-gasifier having a structure in which a crucible is simply placed and heated, the following problems occur. ΓThe material to be heated evaporates and deposits in the low temperature part. Since the refractory of the Γ heating element is attacked by the steam of the object to be heated, the heating element and the refractory must be replaced frequently. When a large amount of Γ atmosphere gas is introduced, the temperature uniformity in the furnace deteriorates due to the uneven temperature of the gas, resulting in a decrease in product quality (such as ultrafine powder). Problems to be Solved by the Invention The present invention solves the various problems of the conventional method as described above, has excellent heat uniformity, and eliminates damage to the refractory in the furnace, the resistance heating element, and the furnace body due to deposition of objects to be heated. It is intended that Means for Solving the Problems As a result of various studies and experiments, the present inventors have succeeded in developing the electric resistance heating type melter-gasifier of the present invention, and the technical structure of the present invention is within the scope of the above claims. The details are as specified in each section, and FIGS. 1 and 2 showing a specific example of the present invention will be described in detail. In this example, the horizontal cross section of the gasifier is circular,
Therefore, we will explain the case where the furnace shell (airtight container), inner shell, and breathable refractory are all cylindrical.
The horizontal cross-sectional shape is not limited. As shown in Fig. 1, the furnace shell 1 serves as an airtight container.
Atmospheric gas such as _N2 or air 1
An air supply pipe 3 for introducing air 6 is provided. An inner shell 2 is provided inside the furnace shell 1, the inner shell is lined with a refractory 7, and a vent hole 4 for atmospheric gas 16 is provided penetrating through the inner shell 2 and the lining refractory 7. An electric resistance heating element 5 (hereinafter simply referred to as a heating element) is installed inside the refractory 7, and a cylindrical refractory 6 with ventilation is installed inside the electric resistance heating element 5.
(hereinafter referred to as a breathable refractory) is installed, and a gasification chamber 20 in which a crucible 8 is placed is provided inside. A predetermined gap 13 is provided between the furnace shell 1 and the inner shell 2, and serves as a passage for atmospheric gas. Further, the annular space between the inner wall of the inner shell and the breathable refractory constitutes an atmospheric gas reservoir. An exhaust pipe 9 for a mixed gas 17 (hereinafter referred to as mixed gas) of the atmospheric gas 16 and the vapor 11 of the object to be heated is installed to pass through the furnace shell 1, the inner shell 2, the refractory 7, and the breathable refractory 6. , mixed gas 1 directly from the top of crucible 8
Eject 7. In some cases, a vacuum pump (not shown) may be connected to the exhaust pipe 9 to forcibly suck the mixed gas 17. Effect Atmospheric gas 16 (solid arrow) entering the furnace from the air supply pipe 3 passes through the vent hole 4 that penetrates the inner shell and the refractory, and enters the gas reservoir 14 outside the breathable refractory 6. Coming in. Here, the atmospheric gas 16 is heated by the heating element 5. Next, the gasification chamber 2 is passed through the breathable refractory 6.
0, due to the ventilation resistance of the breathable refractory 6, a uniform gas flow flows from the entire surface of the breathable refractory 6 into the gasification chamber 20. At the same time, the temperature of the atmospheric gas 16 becomes more uniform due to heat exchange with the breathable refractory 6 heated by the heating element 5. Atmospheric gas 16 enters as a uniform gas flow from the breathable refractory 6, envelops the vapor 11 of the heated material generated from the crucible 8, becomes a mixed gas 17, enters the exhaust pipe 9 above the crucible 8, and is directly It is taken out of the furnace. Therefore, the steam 11 of the heated material generated from the crucible 8 is discharged outside the furnace without contacting anything inside the furnace other than the exhaust pipe 9, and is not used for its original purpose (manufacturing ultrafine powder). Because it is used, the heating element and refractory are not attacked by the steam of the heated object. Since the crucible 8 is heated by the atmospheric gas 16 at a uniform temperature and the radiant heat emitted from the breathable refractory 6, the heating is very uniform. Note that it is more effective to forcibly extract the mixed gas 17 using a vacuum pump (not shown). Although an example of the configuration of a cylindrical gasification chamber has been described above, a gasification chamber having a rectangular cross section or a rectangular cylindrical shape provided with air-permeable refractories on both sides also exhibits similar effects. The characteristics of the members constituting the present invention are as follows. (1) Furnace shells 1 and 12: Airtight containers made of steel that can withstand vacuum to normal pressure. (2) Inner shell 2: Heat-resistant metal (SUS) is preferable. (3) Refractory 7: 200 to 300℃ higher than the heating temperature of the crucible
A material that can withstand high temperatures and also withstand high-temperature atmospheric gases. (4) Heating element 5: A material whose maximum operating temperature is 200 to 300°C higher than the heating temperature of the crucible and can withstand high-temperature atmospheric gas. (5) Ventilation-resistant refractory 6 Γ heat-resistant temperature is 200 to 300℃ higher than the heating temperature of the crucible
expensive. The Γ air permeability is preferably 50 to 90%, especially 70 to 80%. If the ventilation rate is lower than 50%, the gas flow will be uniform, but the pressure loss will be large and only a small amount of atmospheric gas will flow. When the air permeability is higher than 90%, the pressure loss is small and a large amount of atmospheric gas can flow, but the uniformity of the gas flow is disrupted and the physical strength is also reduced. The thickness of the Γ breathable refractory is preferably about 10 to 50 mm.
In particular, it is desirable that the diameter be 5 to 10 times the average diameter of the pores.
Note that the height is 400 mm and the diameter is a cylinder or square tube of about 250 mm, but the size is not limited. If it is thinner than 10 mm, the pressure loss is small and a large amount of atmospheric gas can flow, and heat is easily transferred inside from the resistance heating element, but the uniformity of gas flow and gas temperature is lost. Physical strength is also low. If it is thicker than 50 mm, the pressure loss will be large and only a small amount of atmospheric gas can flow, and heat will be difficult to transfer inside from the resistance heating element, but the gas flow and gas temperature will be more uniform. Physically high too. The average diameter of pores in Γ breathable refractories is 2 mm to 4 mm.
is desirable. If it is smaller than 2 mm, the pressure drop will be large and the uniformity of heating and gas flow will be poor, but clogging will be large. If it is larger than 4 mm, the pressure loss is small and the uniformity of heat and gas flow is poor, but clogging is small. (6) Crucible 8, mixed gas exhaust pipe 9 ΓA material with heat resistance that is 100°C or more higher than the boiling point temperature of the material to be heated (hereinafter referred to as heating temperature). A material that is not attacked by mixed gases at Γ heating temperatures. ΓA material that is not corroded by the object to be heated, such as well-known ceramics such as carbon and alumina, or metals such as pure nickel, can be used. The shape of the end of the exhaust pipe inside the furnace may be shaped like a trumpet, a funnel, a tube with a different diameter, or a bell so that the mixed gas can be easily sucked in, as shown in FIG. Effects of the Invention Since the steam of the object to be heated does not come into direct contact with the furnace body, refractory material, or heating element, the degree of freedom in selecting the material is extremely large. Specifically, it becomes possible to use highly insulating ceramic fiber molded bodies and inexpensive heating elements such as nichrome wire, improving the thermal efficiency of the entire furnace. This furnace is not only a melter-gasifier that simply melts metal chlorides, but is also effective as a heating furnace for materials to be heated, such as zinc, which emit gases that are harmful to refractories and heating elements during melting or heating. It is. Since the refractories and heating elements of the melter-gasifier do not come into contact with harmful gases, there is no damage caused by this, and the lifespan is extended by about four times (from 3 months to 1 year). Uniform heating is achieved by convection of uniformly heated atmospheric gas and radiation heating via breathable refractories. Since the material of the refractory can be freely selected without considering the influence of evaporated substances, it is possible to use highly insulating refractories to create a compact furnace, and at the same time, it is possible to use highly insulating refractories and atmospheric gases. The flow reduces dissipated heat and improves thermal efficiency.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing the inner end shape of an exhaust pipe used in the present invention, and FIG. 3 is a conventional example. FIG. The numbers in the figure are as follows. 1: Airtight container (furnace shell), 2: Inner shell, 3: Atmospheric gas supply pipe, 4: Ventilation hole, 5: Heating element, 6: Breathable refractory, 7: Refractory, 8: Crucible, exhaust pipe, 1
0: object to be heated, 11: vapor of object to be heated, 12: airtight container (lid), 13: gap between furnace shell and inner shell, 14: atmospheric gas reservoir, 15: inner lid, 16: atmospheric gas,
17: Mixed gas, 20: Gasification chamber.

Claims (1)

[Scope of Claims] 1. An inner shell lined with a refractory material and provided with an atmospheric gas vent is placed inside an airtight container provided with an atmospheric gas supply pipe, with a required gap between the inner shell and the inner shell. A breathable refractory is installed inside to provide an atmospheric gas reservoir between the inner wall of the inner shell and the breathable refractory, and an electric resistance heating element is installed in the gas reservoir to generate the gas partitioned by the breathable refractory. characterized in that the inner end opening of the mixed gas exhaust pipe is located above the conversion chamber;
Electric resistance heating melter-gasifier. 2. The electric resistance heating type melter-gasifier according to claim 1, wherein the shape of the inner end of the exhaust pipe is a trumpet shape, a funnel shape, a tube shape with different diameters, a bell shape, or a straight tube shape.