JPH08303953A - Rotary kiln - Google Patents

Abstract

PURPOSE: To make it possible to control residual time without changing the time and enhance throughput per unit time even when the supply of treated articles is unstable by installing a spiral groove continued with the inner surface of a rotary cylindrical body and forcing the cylindrical body to repeat its normal and reversal turning. CONSTITUTION: A heater 1 is partitioned in several sections and controlled so that single temperature adjustment may be available. A rotary cylinder 2 is heated with the heater 1 and provided with a spiral groove continued with the inner surface. A treated article is continuously charged into the continuous inside groove from one end 3 of the rotary cylinder where the treated article is moved in the direction of the other end in the radial groove by turning the rotary cylinder 2. The rotary speed and the rotary direction of the rotary cylinder 2 is arbitrarily controllable. When the rotary direction is in a normal mode, the treated article is moved in the other end direction while the treated article is returned when the rotary direction is in a reversal mode, which makes it possible to prolong the rotation time longer than the inversion time, thereby moving the treated article to in the direction of the other end 4 and discharge the treated article from a discharge opening in continuous mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary kiln for continuously drying and firing powder, granules and the like.

[0002]

2. Description of the Related Art In general, a rotary kiln has a cylindrical body having a structure that is heated from the outside, as is known in the art, and is installed at a slight inclination with respect to the horizontal, and the cylindrical body is inclined while rotating at the same position. The object to be treated is charged into the cylindrical body from the higher side, and is gradually heated to the lower side in accordance with the rotation and heated until it is discharged.

[0003]

When heating is performed using such a rotary kiln, the filling amount of the object to be treated in the rotating cylindrical body is generally 15 to 18%. The reason for this is that the material velocity passing through the cylindrical body is determined by the inclination angle of the rotating cylindrical body, the input amount, the number of rotations, and the like. The time for the input material to pass through the cylinder, that is, the residence time of the material to be treated, is determined by the same factors as above.

When the inclination angle of the cylindrical body is 0 °, the residence time of the object to be treated is calculated by the following (Equation 1).

[0005]

[Equation 1]

However, in (Formula 1), τ is the residence time (min), N
Is the number of revolutions (rpm), β is the angle of repose of the material (°), and F is the material supply amount.
(kg / min), L is the cylinder length (m), ρS is the material bulk density (kg / m ³ ), and D is the cylinder inner diameter (m).

Therefore, the residence time can be determined by the relationship between the number of revolutions and the material supply amount when the tilting angle of the rotating cylinder is 0 °. If an attempt is made to lengthen the residence time, the material supply amount must be reduced at a predetermined rotation speed, and the processing capacity will be reduced accordingly. Further, in order to increase the material supply amount, the number of rotations must be decreased, and in this case, the heating efficiency drops.
The same applies when the cylinder is inclined. In some cases, the continuously charged materials are dispersed in the rotating cylinder to mix materials having different processing times. Further, if the material supply amount is not constant, there is a problem that the residence time in the cylinder changes and uniform heat treatment cannot be performed.

[0008]

In order to solve the above-mentioned problems, the present invention provides a cylindrical body (rotary cylinder) which is heated from the outside and has a spiral groove which is continuous on the inner surface and rotates. The object to be processed is supplied from one end (supply port) of the rotary cylinder into the continuous spiral groove inside the rotary cylinder, and the object to be processed passes through the continuous spiral groove by the forward and reverse rotation of the rotary cylinder. Moving. The number of rotations and the direction of rotation of the rotary cylinder can be arbitrarily controlled. When the rotation direction is one (normal rotation), the object to be processed moves toward the other end (exhaust port) of the cylinder, and the rotation direction is opposite ( In the case of (reverse rotation), the processed product returns to the supply port. Therefore, by setting the forward rotation time longer than the reverse rotation time, the mixture as a whole moves toward the discharge port. By repeating normal rotation and reverse rotation as one cycle in this manner, the object to be processed moves from the supply port to the discharge port of the rotary kiln.

[0009]

As described above, in the present invention, the inner surface of the rotary cylinder has a continuous spiral groove, and by increasing the effective volume in this groove, the filling amount of the object to be treated can be increased,
The residence time becomes constant even if the filling amount in the groove changes, that is, the input amount of the object to be processed changes.

Further, since the objects to be processed are successively moved in the continuous spiral groove, the objects to be processed having different supply times can be processed without being mixed. Further, the temperature difference between the surface layer and the central portion of the object to be treated also decreases as the rotation speed increases. However, when the rotation speed is high, the object to be processed moves quickly in the rotary cylinder, so that the pitch of continuous grooves is made small or a long rotary cylinder is required to obtain a predetermined temperature keeping time.

In the kiln of the present invention, the rotation direction as well as the rotation direction of the rotary cylinder can be controlled arbitrarily, so that when the rotation direction of the cylinder is forward, the object to be processed moves to the side opposite to the supply port (discharge port) and rotates. When the direction is reversed, the object to be processed is returned to the supply port. Therefore, by setting the forward rotation time longer than the reverse rotation time, the entire object to be processed moves toward the discharge port. Therefore, the residence time in the cylindrical body can be arbitrarily controlled by changing the time difference between forward rotation and reverse rotation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a rotary kiln of the present invention, and 1 is a heater. This heater is divided into several zones, each of which is controlled so that its temperature can be adjusted independently. Reference numeral 2 denotes a rotary cylinder which is heated by the heater 1 and has a spiral groove which is continuous on the inner surface and rotates. FIG. 2 shows a rotary cylinder 2 and a heater 1.
A sectional view taken along line AA ′ of FIG. The object to be processed is put into a continuous groove inside from one end (supply 12) of the rotary cylinder shown in FIG. The object to be processed moves in the direction of the other end 4 in the continuous spiral groove by the rotation of the rotary cylinder.
The rotation speed and rotation direction of the rotary cylinder can be controlled arbitrarily. When the rotation direction is forward, the object to be processed moves toward the other end, and when the rotation direction is reverse, the object to be processed returns to the supply port side. Therefore, by setting the forward rotation time to be longer than the reverse rotation time, the object as a whole moves toward the other end 4 and is continuously discharged from the discharge port. The residence time in the cylinder of the processed material using this rotary kiln is calculated by the following (Equation 2).

[0013]

[Equation 2]

However, in (Equation 2), τ is the residence time (h), P
n is the number of continuous spiral grooves, N is the number of revolutions (rpm), T1
Represents the forward rotation time (min), t represents the difference between the normal rotation time and the reverse rotation time (min), and Ts represents one cycle time (min).

As described above, by arbitrarily setting the rotation speed or the difference between the normal rotation time and the reverse rotation time, the residence time of the object to be processed in the rotary cylinder can be freely controlled.

[0016]

As described above, in the rotary kiln of the present invention, a continuous spiral groove is provided on the inner surface of the rotating cylinder, and the cylinder is repeatedly rotated in the normal direction and the reverse direction. The residence time did not change even when the supply of the material was unstable, and by allowing the residence time to be controlled arbitrarily, a sufficient heat treatment could be performed, and the throughput per unit time could be greatly improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a rotary kiln according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA ′ of FIG.

[Explanation of symbols]

 1 heating heater 2 rotary cylinder with continuous spiral groove 3 supply port 4 discharge port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Hanaoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A rotary kiln characterized by comprising a cylindrical body which is heated from the outside and has a continuous spiral groove on its inner surface and which rotates, and the direction of rotation thereof periodically repeats normal rotation and reverse rotation. . 2. A material to be heated is supplied from one end of a rotating cylindrical body to the inside thereof, and is heated while repeatedly moving forward and backward in a continuous spiral groove. 2. The rotary kiln according to claim 1, wherein the material to be heated is discharged from the other end of the cylinder by setting the total number of revolutions during forward rotation in one cycle of forward rotation and reverse rotation to be higher than that during reverse rotation. A heat treatment method using.