JPH08200617A - Rotary kiln burner for refining ferroalloy - Google Patents

Abstract

PURPOSE: To efficiently burn pulverized coal by forming the upper half of a burner tile in a cylindrical shape, and providing an obliquely lower cutout directed from the end of the burner tile toward the burner base at the lower half. CONSTITUTION: A heavy oil passage 2 for auxiliary fuel is provided at the center, a pulverized coal fuel passage 3 for supplying pulverized coal of main fuel is provided at the outer periphery and a combustion air passage 4 for supplying combustion air is provided further at the outer periphery of a burner 1. On the other hand, a burner tile 5 is provided at the end of the burner as to surround the passages. The tile 5 is formed in a cylindrical shape, and provided with a cutout 6 directed toward obliquely downward with respect to the burner base at the lower half near the end. Thus, the adhesion of unburnt carbon to the inner surface of the lower half of the tile is eliminated, and hence the burning damage to the tile based on the abnormal combustion due to it is obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner device for a ferroalloy smelting rotary kiln, and more particularly to a structure of a burner that uses pulverized coal as a main fuel in a ferroalloy, especially a ferronickel smelting rotary kiln.

[0002]

2. Description of the Related Art Ferroalloys, particularly rotary kilns used for smelting ferronickel, mix raw ore with a reducing material to dry, raise the temperature and preliminarily reduce the raw material. The flame from the burner used as the main raw material is used.

As a burner used in the rotary kiln, since the rotary kiln usually has a length ranging from several tens of meters to 100 meters or more, one having a stable combustion property and a stable long flame can be formed. Required.

On the other hand, after the oil shock, pulverized coal obtained by crushing inexpensive coal has been widely used as a fuel for the burner of the rotary kiln for ferroalloy smelting, as a substitute for expensive heavy oil.

However, pulverized coal has the drawback of being inferior in ignitability to heavy oil. As a result, not only is the flame destabilized, but it is also discharged unburned in the kiln together with dust and ore to the outside of the kiln. Therefore, there is a disadvantage that the amount of fuel used increases and the fuel consumption rate decreases.

For these reasons, conventionally, the following four methods have been taken in order to solve these drawbacks and improve the ignitability of the pulverized coal burner.

The first method is a method of simultaneously burning heavy oil as an ignition for improving the ignitability of pulverized coal, and the second method is to insert the burner tip into the kiln body further from the rotary kiln outlet, A method of promoting ignition of pulverized coal by radiant heat from a kiln refractory and a sinter, and a third method is a method of attaching a burner tile to the tip of a burner to promote ignition of pulverized coal. The method is to enrich the combustion air with oxygen.

[0008]

However, in the first method, if the amount of heavy oil to be burned at the same time is excessively reduced, the ignition promoting effect of the heavy oil is reduced. Therefore, in order to make the combustibility of pulverized coal similar to a heavy oil burner burner. Is not economically effective because it requires mixed burning with a considerable amount of heavy oil of 20% or more, and in the second method, the diameter of the rotary kiln is usually 4 to 4.
Since it is as large as 5 meters, it is difficult to receive the supply of radiant heat that can significantly improve the ignitability of pulverized coal.

In the third method, although the ignitability of the pulverized coal is improved, unburned carbon adheres to the inner surface of the burner tile, particularly the inner surface of the lower half, which causes abnormal combustion and burner tile. However, in the fourth method, since the expensive pure oxygen is used, there is a problem that the advantage of switching from heavy oil to pulverized coal is small, and any method is sufficiently satisfactory. It was hard to say how to improve.

Therefore, the present invention is a rotary kiln burner for smelting ferroalloys, which eliminates the drawbacks of the conventionally proposed method for improving the ignitability of pulverized coal and enables efficient pulverized coal combustion. It is intended to provide.

[0011]

A rotary kiln burner for smelting a ferroalloy according to the present invention for achieving the above object comprises a fuel passage in the central portion and a combustion air passage in the outer periphery thereof and the combustion air. In a burner device in which a cylindrical burner tile is provided at the tip of a passage, the upper half of the tip of the burner tile is made cylindrical as it is, and the lower half is slanted downward from the tip of the burner tile toward the burner base. It has a cutout portion.

[0012]

In the burner for a rotary kiln according to the present invention described above, since the lower half of the tip of the burner tile formed into a cylindrical shape is cut out obliquely downward, the burner tip is formed from the burnt ore. Radiant heat is easily received, the amount of heavy oil mixed and burned as an ignition can be greatly reduced, and the burner tip is placed inside the rotary kiln body without enriching combustion air with expensive high-purity oxygen. The ignitability of pulverized coal can be improved without inserting it deeply. In addition, since the lower half of the burner tile is notched, the problem of unburned carbon adhering to the lower surface of the burner tile is solved, so that the flame is stabilized and combustion efficiency is increased. It is also possible to significantly reduce the fuel consumption rate.

FIG. 1 is a partial sectional side view showing one embodiment of a burner for a rotary kiln according to the present invention.
In FIG. 1, a burner 1 is provided with a heavy oil burner passage 2 for auxiliary fuel at the center thereof, a pulverized coal fuel passage 3 for supplying pulverized coal as a main fuel is provided at an outer peripheral portion thereof, and further an outer peripheral portion thereof. A combustion air passage 4 is provided for supplying combustion air to the. On the other hand, a burner tile 5 is provided at the tip of the burner so as to surround these passages. The burner tile 5 has a cylindrical shape, and a notch portion 6 is provided in the lower half of the burner tile 5 in the vicinity of the tip of the burner tile 5 so as to extend obliquely downward with respect to the burner base.

The burner of the present invention has a structure in which the attached burner tile is provided with the notch in the lower half of the tip as described above, and therefore, the conventional burner having a complete cylindrical burner tile is used. In this case, the unburned carbon, which had a problem in (1), does not adhere to the inner surface of the lower half of the burner tile, and therefore burner tile burnout due to abnormal combustion does not occur.

Further, in the burner according to the present invention, since the lower half of the burner tile is cut out, the heat receiving surface of the radiant heat from the ore increases, so that the burner tile exhibits a higher heat receiving efficiency than the conventional burner tile. Therefore, the ignition and combustion efficiency of the burner can be further improved.

[0016]

EXAMPLES In a rotary kiln for treating 60 tons of nickel-containing raw material ore using the burner for rotary kiln of the present invention having the shape shown in FIG. 1, the ore is mixed with a reducing material, dried and heated. The preliminary reduction treatment was continuously performed and compared with the treatment results before the use of this burner. The pulverized coal / heavy oil co-firing rate of 3 months before using this burner, that is, when treated using a conventional burner with burner tiles, was 77.0 each on average monthly.
%, 83.2%, 85.3%, and three-month average of 8
Although it was 1.8%, when the burner of the present invention was used, the mixed burning rate for 3 months after the start of use was 9 on average each month.
6.4%, 99.1%, 99.3%, 3 months average is 98.3%, the co-firing rate is improved by 16.5%, and the amount of heavy oil used is increased without using expensive pure oxygen. We were able to reduce significantly.

Further, the fuel consumption rate is also reduced by about 12% as compared with the case of using the conventional type burner, and in the burner according to the present invention, burner tiles are not burned or deformed even one year after installation. We were able to continue operation stably.

[0018]

As described above, the burner for a rotary kiln according to the present invention has the following effects as a whole. (1) Since the ignitability of pulverized coal is improved, the pulverized coal / heavy oil mixed burning rate is remarkably improved, and as a result, the cost of using expensive heavy oil can be significantly reduced. Further, it is not necessary to use expensive pure oxygen at the time of ignition and combustion, and combustion may be performed using normal air. (2) As a result of improving the heat receiving effect of radiant heat, the combustion efficiency of pulverized coal is improved and the amount of pulverized coal discharged from the rotary kiln without being burned is reduced, and as a result, the fuel consumption rate is reduced. (3) The amount of unburned carbon adhering to the lower surface of the burner tile is reduced, abnormal combustion due to this is eliminated, and as a result burnout and deformation of the burner tile do not occur, and long-term continuous operation of the rotary kiln is possible.

[Brief description of drawings]

FIG. 1 is a partial sectional side view showing an embodiment of a burner for a rotary kiln according to the present invention.

[Explanation of symbols]

 1 Burner for rotary kiln 2 Fuel oil burner passage for auxiliary combustion 3 Pulverized coal passage for main combustion 4 Combustion air passage 5 Burner tile 6 Notch

Claims (1)

[Claims] 1. A burner device in which a fuel passage is provided in a central portion, a combustion air passage is provided on the outer periphery of the fuel passage, and a cylindrical burner tile is provided at a tip of the combustion air passage, and an upper half portion of the burner tile is provided. As it is cylindrical,
A rotary kiln burner for smelting ferroalloy, comprising a notched portion in the lower half of the burner tile from the tip of the burner tile toward the burner base.