JPS62149824A - Method for controlling flow rate of oxygen in sintering machine - Google Patents

Abstract

PURPOSE:To efficiently supply oxygen for combustion and to reduce production cost of sintered ore, by carrying out sintering while suitably controlling the ratio of introduced flow rate of oxygen for combustion to total flow rate of exhausted gas in wind box. CONSTITUTION:Sintering material is supplied from a material supply part 12 on a sintering bed 13 of Dwight-Lloyd sintering machine, ignited by an ignition furnace 4, air is downwardly sucked through the wind boxes 2, 2... linkedly provided to a main flue 3 and oxygen for combustion is supplied from upside through an oxygen blowing hood 6 to carry out sintering. In the sintering operation, flow meters 5, 5... are arranged to the boxes 2, 2 to measure respective exhausted gas flow rates, further total flow rate of exhausted gas is obtd. by adding calculation at an arithmetic adder 10. On the other hand, flow rate of the oxygen for combustion is measured by an oxygen flowmeter 9, and the ratio of introduced flow rate of the oxygen for combustion to the total flow rate of exhausted gas is controlled through an oxygen flow rate control valve 8 so that the ratio becomes <0.15 at a rate setting device 11.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for controlling the oxygen flow rate of a sintering machine, and more specifically, a method for efficiently supplying the minimum necessary amount of oxygen to increase the productivity of sintered ore. The present invention relates to a method for controlling the oxygen flow rate of a sintering machine that has been successfully used.

[Prior Art] FIG. 2 is a schematic explanatory diagram showing a typical configuration example of a Dwight Lloyd sintering machine. As shown in FIG. 2, in the Dwight Lloyd sintering machine, the raw material supplied from the raw material supply section 12 is fed into the ignition furnace 4 while sucking air from above from the lower part of the sintering bed 13 into which the raw material layer is charged. The coke powder mixed in the raw material is ignited to sequentially burn the coke powder mixed in the raw material, thereby promoting sintering and melting reactions between the raw material ore particles. Therefore, the productivity of sintered ore in a sintering machine largely depends on the combustion rate of the coke breeze. For this reason, various methods have been tried to improve the combustion rate of coke breeze. A method has been proposed in which the gas penetrating the layer is oxygen-enriched air.

[Problems to be Solved by the Invention] In addition, in the sintering machine, as shown in FIG.
The opening degree of the damper 16 is adjusted. However, passing through the sintering bed 13 from top to bottom, each wind box 2
The amount of air sucked in changes depending on the ventilation resistance of the raw material layer on each sintering bed 13 located at the upper part of the wind box 2. The ventilation resistance of the raw material layer changes from moment to moment in response to changes in the filling state of the raw material, the raw material particles, etc., and the amount of exhaust gas flowing through each wind box 2 is constantly changing.

When supplying oxygen to the sintering raw material on the sintering bed 13, there is a method in which the supply gas flow rate is kept constant and the total oxygen supply amount is adjusted by controlling the oxygen content in the supply gas. If adopted, not only the amount of air passing through the sintering bed 13 changes due to the above-mentioned reasons, but also the oxygen concentration, so these two changes overlap and the amount of oxygen supply layer changes greatly, Operational stability will be significantly reduced.

On the other hand, the height of raw material filling on the sintering bed 13 is 300 to 800.
Since the diameter is about 1 mm, the time for gas such as air to pass through the sintering bed 13 is extremely short, only about 1 second. Furthermore, coke breeze does not start a combustion reaction with oxygen unless it is above 600°C, and the time that air and coke breeze are in contact at temperatures above 600°C is extremely short, so the efficiency of the combustion reaction is extremely low.

In such a sintering process, not all of the added oxygen contributes to the combustion of coke breeze, and the amount of oxygen supplied is unstable, so oxygen is inevitably supplied in excess. Under normal operating conditions, surplus oxygen is wastefully discharged.

As mentioned above, in the conventional technology, no consideration is given to the optimal oxygen addition range in which oxygen can be effectively utilized.
From this point of view, it is desired to develop a control technology to maintain the optimum amount of oxygen added.

Therefore, in view of the above-mentioned current situation, an object of the present invention is to efficiently supply oxygen and reduce the production cost of sintered ore.

[Means for solving the problem] The present invention measures the introduction flow rate of combustion oxygen in a combustion oxygen supply zone and the total flow rate of exhaust gas in the wind box related to the zone, and calculates the introduction flow rate of combustion oxygen and exhaust gas. Ratio to total flow rate is 0
．． The key point is that sintering is performed while controlling the temperature to be less than 15.

[Function] The present invention is configured as described above, but the point is that in the sintering machine 1 as shown in FIG. The system operates while adjusting the flow rate of oxygen introduced for combustion.

The flow rate of oxygen introduced is adjusted such that the ratio α between the flow rate of oxygen introduced and the flow rate of exhaust gas in the wind box 2 into which oxygen is introduced becomes a predetermined value. The value of the ratio α is
This is an important requirement for improving the utilization efficiency of introduced oxygen and further improving the productivity of sintered ore, and as described below, it is necessary that it be less than 0.15.

FIG. 3 is a graph showing the relationship between α and the oxygen utilization efficiency, and the oxygen utilization efficiency is expressed by the following equation (1). Sho (1
) In the formula, "the amount of oxygen that contributed to the combustion of coke breeze 1" is a value determined by numerical calculation based on the measured value of co2?fA degrees in the exhaust gas flow rate.

Oxygen utilization efficiency = X100 (%) ・・・・・・(1) 3rd
As is clear from the figure, as the oxygen introduction flow rate increases and α (oxygen introduction flow rate/total exhaust gas flow rate) increases, the oxygen utilization efficiency decreases. Especially when α becomes 0.15 or more,
The decrease in oxygen utilization efficiency becomes significant.

From the results shown in Figure 3, the following can be considered. That is, the combustion of coke breeze does not depend only on the introduced oxygen concentration, but is influenced by the reaction contact time between oxygen and coke breeze and other factors. This is true in actual operation of the sintering machine.
Considering that the basic unit of oxygen for combustion is generally expensive, it is important to operate the sintering machine properly within a range with high oxygen utilization efficiency in order to reduce the manufacturing cost of the sintering machine. This suggests that there is.

[Example] Fig. 1 is a schematic explanatory diagram of a Dwight Lloyd type sintering machine 1 (hereinafter simply referred to as sintering machine) configured to carry out the method of the present invention. In Fig. 1, 3 is the main exhaust flue, 5 is the exhaust gas flow meter, 6 is the oxygen blowing hood, 7 is the oxygen introduction pipe, 8 is the oxygen flow rate adjustment valve, 9 is the oxygen flow meter, and 10 is the exhaust gas flow rate meter. The calculation adder 11 is a ratio setting device for the introduced oxygen and the exhaust gas flow rate. Other parts corresponding to those of the prior art shown in FIG. 2 are given the same reference numerals. The oxygen blowing hood 6 corresponds to the combustion oxygen supply zone, and the oxygen blowing hood 6 corresponds to the combustion oxygen supply zone.
may be located on one wind box 2, but may be located on multiple wind boxes 2 (three locations in the embodiment) without any problem.

A method for controlling the flow rate of oxygen introduced into the sintering machine 1 will be explained. The exhaust gas flow rate of each wind box 2 related to the oxygen blowing hood 6 is
It is measured by flowmeter 5. The exhaust gas flow rate of each wind box 2 measured by the flowmeter 5 is added by an arithmetic adder 10, and the total exhaust gas flow rate in the wind box 2 into which oxygen is introduced is measured.

Arithmetic adder 10 is connected to a ratio setter.

On the other hand, the combustion oxygen supplied to the sintering bed 13 is supplied to the oxygen blowing hood 6 via the oxygen introduction pipe 7, the oxygen flow rate control valve 8, and the oxygen flow meter 9. A total of 9 are connected to the ratio setter 11. The oxygen flow rate in the oxygen flow meter 9 is adjusted by the oxygen flow control valve 8 so that the ratio α between the oxygen flow rate and the exhaust gas flow rate becomes a value set by the ratio setting device 11.

Here, the value set by the ratio setting device 11 is a value such that the ratio α between the oxygen introduction flow rate and the exhaust gas flow rate is less than 0.15, as described in connection with FIG. 3 above. In this way, the ratio between the oxygen introduction flow rate and the exhaust gas flow rate can be kept constant at all times.

The present invention finally controls the oxygen introduction flow rate to set the value of α to 0.
Although the value of α is controlled to be less than 15, it goes without saying that the exhaust gas flow rate exists in addition to the oxygen introduction flow rate as a factor that influences the value of α. The exhaust gas flow rate also depends on the filling state of the sintering raw material, the raw material particles, and other requirements. Therefore, in the present invention, α is 0.15
The requirements to be controlled so as to be less than 100% are not limited to the oxygen introduction flow rate, but must also take into consideration the various other requirements mentioned above.

Table 1 shows the results of actual operation using the sintering machine 1 shown in FIG. As is clear from the results in Table 1, when α becomes 0.15 or more, the oxygen consumption rate decreases to 408 rn
”/T-5teel, so it is understood that the optimum ratio α is less than 0.15.

Table 1 [Effects of the invention] By carrying out the method of the present invention as described above,
It is now possible to maintain high oxygen utilization efficiency in the sintering machine, making it possible to perform economical oxygen addition operations and lowering the oxygen consumption rate, which can greatly contribute to improving the productivity of sintered ore. It is something.

[Brief explanation of drawings]

Figure 1 shows a sintering machine 1 configured to carry out the method of the present invention.
FIG. 2 is a schematic explanatory diagram showing a typical conventional technique of a Dwight Lloyd sintering machine, and FIG. 3 is a graph showing the relationship between ratio α and oxygen utilization efficiency. 1... Sintering machine 2... Wind box 3... Main exhaust flue 4... Ignition furnace 5... Flow meter 6
...Oxygen blowing hood 7...Oxygen introduction piping 8...
・Oxygen flow rate adjustment valve 9...Oxygen flow meter

Claims (1)

[Claims] In the oxygen flow rate control method for a Dwight Lloyd sintering machine,
Measure the flow rate of combustion oxygen introduced in the combustion oxygen supply zone and the total flow rate of exhaust gas in the wind box related to the zone, and make sure that the ratio of the flow rate of combustion oxygen introduced and the total flow rate of exhaust gas is less than 0.15. A method for controlling an oxygen flow rate in a sintering machine, which is characterized by performing controlled sintering.