JPH0222632Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improved structure of a rotary kiln, especially for use at high temperatures.

[Conventional technology]

Conventional rotary kilns of this type have an external heating system in which the outside of the middle part of the furnace core tube, which is made integrally with a heat-resistant steel tube, is surrounded by a relatively short box-shaped electric heating furnace that is concentric with the core tube and can control the temperature. In most cases, the furnace core tube supporting tires fitted on both sides of the heating furnace in the furnace core tube are placed on two or more sets of support wheels connected in series on the same line. Generally, a sprocket attached to the shaft of one of the support wheels is driven by a motor with a speed reducer via a chain and a speed reducer.

[Problem that the invention attempts to solve]

However, recently, products such as magnetic powders such as iron oxide powder and ferrite particle powder have appeared that need to be heated at temperatures as high as 1,000 degrees C or more, and with ordinary steel pipes, the furnace core tube may be deformed or undergo high-temperature corrosion during heating. Rotary kilns could not be used for heat treatment of this type of product because of the following.

For this reason, alumina, silicon carbide or silicon carbide
It is conceivable to manufacture rotary kilns using ceramic pipes containing 70-80% silicon nitride, 20-30% silicon nitride, or 45% titanium oxide and 45% alumina, but these ceramic pipes have poor dimensional accuracy, The length is often limited due to roundness, etc., and currently, with materials with high heat resistance,
Usually less than 2 meters long.

Moreover, ceramic pipes are difficult to weld, have poor adhesive strength, and are expensive, so it is not preferable to connect them in the longitudinal direction.

Therefore, it is used at relatively low temperatures, and the drive mechanism,
The inlet and outlet furnace core tubes, which have a complicated structure for charging, discharging, and transferring materials, are made of stainless steel pipes as before, and only the intermediate heating section is made of heat-resistant material such as the ceramic pipe mentioned above. It is conceivable that the two could be made from a plastic pipe and used by connecting the two.

However, heat-resistant pipes generally have low tensile strength and impact force, are large in hardness, and have inferior dimensional accuracy and roundness compared to stainless steel pipes, are difficult to process, and have an extremely small coefficient of thermal expansion. be.

Therefore, welding, flange joints, and other conventional joining means used in this type of equipment cannot be used to connect stainless steel tubes and heat-resistant pipes.

[Means for solving problems]

Therefore, the inventor, as shown in Figures 1 to 4,
The heat-resistant cylindrical body part of the furnace core tube that passes through the heating furnace 1A is made into a simple cylinder, and the metal inlet and outlet furnace core tubes are arranged on the same axis as this,
Connected to allow thermal expansion through a flexible joint such as a telescope type expansion joint that uses highly elastic ring packing and push ring commonly used for water supply piping and other piping, and By connecting each furnace core tube through a synchronous drive means used in other long rotary kilns for cement production, high-temperature gas can It is possible to connect the heat-resistant cylindrical body and the joint in a manner that prevents leakage and damage, and allows a heat-resistant pipe, which can only be obtained in a relatively short length, to be effectively utilized as a heating zone of a rotary kiln.

That is, the present invention is a flexible, improved version of the conventionally known expansion pipe joint, in order to connect heat-resistant pipes with different properties and ordinary stainless steel pipes to construct a special device that rotates like a rotary kiln. The objective was to be achieved by skillfully combining a pipe joint and a synchronous rotation means.

[Effect]

In this way, the heat-resistant cylindrical body is made into a simple cylindrical shape, which is sandwiched from both sides by metal inlet and outlet hearth tubes so as to slightly overlap in the axial direction.
The heat-resistant cylindrical body is flexibly and airtightly supported via a flexible ring fitted inside a sleeve fixed to at least one end thereof. Even if the end portions of the furnace core tubes that follow the furnace core tubes expand thermally due to heating and a dimensional difference occurs in the length and diameter direction, the flexible ring is only slightly deformed and each furnace core tube, , can be extended freely.
Also, since the flexible ring is made of asbestos board or other highly elastic, airtight, heat-resistant material, such slight deformation will create a gap between the heat-resistant cylindrical body and the sleeve, allowing gas to leak. Without a doubt,
It is possible to maintain airtightness by expanding between the two.

In addition, even if the axes of each furnace core tube and the heat-resistant cylindrical body do not perfectly match, when these rotate, the flexible ring with low deformation resistance deforms elastically, so the heat-resistant cylindrical body There will be no strain on the department. Furthermore, the heat-resistant cylindrical body, which is relatively short and light in length, is held at both ends by the flexible rings, and is driven at the same speed from both sides by the frictional force, so that almost no torsional moment is generated. There is no slippage between the cylindrical body and the flexible ring. this is,
The same applies even if the sleeve in one of the furnace core tubes is omitted and one end of the heat-resistant cylindrical body is supported by the furnace core tube.

Furthermore, the inlet and outlet furnace core tubes, which have relatively low temperatures, are made of stainless steel tubes and other metals as before, and only the middle section, which is heated to a high temperature, is made of heat-resistant pipes. Since it is connected to the furnace core tube, most of the heat-resistant cylindrical body can be effectively used as a heating zone.

〔Example〕

As illustrated in Figure 2, length 1700mm, width 780mm
In the center of the heating furnace 1A, which is made into a box shape with a height of 880 mm and a 40 kW electric heating means that can control the temperature, there is a
A heat-resistant cylindrical body made of alumina with a thickness of 4.5 mm passes through the body, and a heat-resistant cylindrical body with an outer diameter of 139.8 mm and a thickness of 5.5 Inlet furnace core tube made of SUS304TB of JIS G 3463 stainless steel pipe for boilers and heat exchangers of mm, and stainless steel pipe for piping with external diameter of 165.2 mm and thickness of 3.4 mm (JIS G 3459)
An outlet furnace core tube made of SUS304TP is installed. As shown in FIGS. 1 and 4, the end of each furnace core tube near the heat-resistant cylindrical body is slightly larger than the furnace core tube, and has a flange 6A at one end and a flange 6A at the other end. It is equipped with an end plate 6C having a hole 6B that fits into the outer diameter of the furnace core tube, and a stopper ring 6D having a hole with the same diameter as the end plate 6C in the middle (this part is shown in FIG. 1). A sleeve made of cast stainless steel (SCS1 of JIS G 5121) is welded. The total length of the inlet core tube including the sleeve is 1150 mm, and the total length of the outlet core tube is 750 mm. The inlet furnace core tube and outlet furnace core tube are each made of cast stainless steel (SCS1).
tires are installed. In the inlet furnace core tube, one tire 7-1 is integrally cast with the sleeve on the outside of the end plate 6C, and the outer periphery of the flange 6A serves as the other tire.

As shown in FIG.
It is placed on a pair of support wheels 7B, and one support wheel 7B
A sprocket 7C is attached to the shaft 7B-2 of the shaft 7B-1, and is driven by a reducer-equipped motor 7E with an output of 0.75 kW via a reducer 7D consisting of a sprocket and a chain attached to the intermediate portion 7D-1.

Since the intermediate shaft 7D-1 is connected to the other reducer 7D-2 extending along the heat-resistant cylindrical body, the tire 7-1 having the same diameter as the tire 7 rotates at a synchronous speed. Therefore, the inlet furnace core tube and the outlet furnace core tube always rotate at the same rotation speed.

Further, the sleeve 6-2 of the outlet furnace core tube is connected to the tire 7-1 and the stopper ring 6 as shown in FIG.
It is not much different from the sleeve shown in Fig. 1 except that it does not have D and its size, but between the flange 6A and the end plate 6C, there is a furnace core tube that can freely expand and contract in the length direction. A packing end ring 6D-2 is formed with a hole 6-E that can loosely fit into the outer diameter of the furnace core tube. Sleeves and 6 of the inlet and outlet core tubes
-2 is equipped with a push ring with a flange 8A that can slide concentrically in the axial direction on the inside thereof, and the push ring and sleeve, 6-2, and an inlet furnace core tube or an outlet furnace core opposite thereto. A plurality of flexible rings made by cutting out asbestos plates in an annular shape are loaded between the pipe and the tube. The flexible ring is constructed by tightening bolts 8B and nuts 8C inserted into a plurality of holes equally spaced in the flange 6A of the sleeve 6-2 and the flange 8A of the push ring. When pushed toward the heat-resistant cylindrical body, it expands in the axial direction and comes into close contact with the outer periphery of the cylindrical body.

While evenly feeding a mixture of barium carbonate and iron oxide at a rate of 25 kg/hour from one end to the inlet core tube of the rotary kiln configured as described above, the motor 7E is used to move the inlet core tube, heat-resistant cylindrical body, and outlet furnace. When the core tube is rotated as a unit, the raw material is preheated to about 300 degrees Celsius by a heating means (not shown) in the inlet furnace core tube, and then
It is fed into the heat-resistant cylindrical body and heated to 1200 degrees Celsius by heating means. The heated raw material is sent to the outlet furnace core tube, where it is slowly cooled to become barium ferrite having the desired quality, and is discharged from one end of the barium ferrite to the outside of the furnace. The processing time for raw materials in the furnace core tube is about 20 minutes, but the residence time in the furnace depends on the rotation speed of the motor 7E, which is controlled according to the slope at the time of installation and the product brand. Therefore, the time can be adjusted between 5 and 30 minutes. The temperature of the heating furnace and preheating means can also be controlled at 1100 to 1300 degrees Celsius depending on the product brand.

Sleeves, push rings, flexible rings, etc.
It is not necessarily necessary to provide it in both the inlet and outlet furnace core tubes, and if the heat-resistant cylindrical body is relatively short and light and the weight of the material to be treated that remains inside is small, it is possible to prevent a slight leakage of exhaust gas. If it is not a problem, you can omit one of them. An example is shown in Fig. 5. The tail end of a heat-resistant cylindrical body made of an alumina tube with a thickness of 10.0 mm has an inner diameter of 170 mm.
It is inserted and supported inside an outlet furnace core tube made of stainless steel pipe for piping with an outer diameter of 216.3 mm and a thickness of 4 mm via a silicon carbide tube 4A having a diameter of 15 mm, a thickness of 15 mm, and a length of 150 mm. A tire made of stainless steel cast steel is directly cold-fitted onto the outside of the furnace core tube, and is prevented from rotating with a not-shown clasp, but other parts are the same as in the previous embodiment. be.

The material to be used for the heat-resistant cylindrical body must be determined by considering its size, heating conditions of the material to be treated, amount of treatment, etc., but alumina, silicon carbide, or silicon carbide 70 to 80 % and silicon nitride 20-30% or titanium oxide 45% and alumina
In addition to ceramics containing 45% or the like, any material having heat resistance and specified strength, such as a special heat-resistant alloy tube or quartz tube, may be used.

Furthermore, as the flexible ring, in addition to asbestos board, alumina felt can also be used.

In addition to the friction wheels shown in the above embodiments, the synchronous drive means may include multiple sets of girth gears and pinions of the same diameter connected via a common shaft, or multiple DC motors controlled to rotate synchronously. May be used.

[Effect of idea]

If the rotary kiln has the configuration described above in detail, the heat-resistant cylindrical body or its joints will not be damaged even when the material to be processed is heated to a high temperature of 1000 degrees C or more, and the high-temperature gas will not be damaged. Since there is almost no leakage, it is possible to prevent accidents that would cause the processing plant to be shut down due to equipment failure. Therefore, it is possible to improve the operating rate of the device, and most of the heat-resistant pipes, which are expensive and difficult to obtain in long lengths, can be effectively used as a heating zone, which is extremely useful industrially.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a portion that best represents the features of the rotary kiln of the present invention, Fig. 2 is a longitudinal cross-sectional view showing an embodiment of the present invention, and Fig. 3 is a cross-sectional view taken along the - line in Fig. 2. The - line represents the position shown in FIG. Figure 4 shows the sleeve 6 of the outlet furnace tube.
Fig. 5 is a longitudinal sectional view showing a different embodiment of the end of the outlet furnace core tube.

Claims (1)

[Scope of utility model registration request] A heat-resistant cylindrical body disposed horizontally and equipped with a heating means on the outside thereof, and a metal inlet disposed on the same axis as the heat-resistant cylindrical body, sandwiching it and slightly overlapping in the axial direction on both sides thereof. A furnace core tube and an outlet furnace core tube, a sleeve fixed to an end of at least one of the furnace core tubes closer to the heat-resistant cylindrical body, and the inlet furnace core tube and the outlet furnace core. synchronously rotating driving means attached to each of the tubes, a press ring attached to the inside of the sleeve so as to be able to slide in the axial direction concentrically therewith, the press ring and the inside of the sleeve, and a heat-resistant, airtight flexible ring that is fitted between the opposing heat-resistant cylindrical bodies and bulges in the radial direction when the press ring is pushed in the axial direction, and is in close contact with the heat-resistant cylindrical bodies; A rotary kiln characterized by: