JPH01316429A - Method for manufacturing sintered ore - Google Patents

Abstract

PURPOSE:To stably manufacture sintered ores of high quality while suppressing the corrosion of an exhaust system at the time of sintering ores by a Dwight- Lloyd sintering machine by regulating the air amt. in a circulating exhaust system in accordance with the air amt. in a main exhaust system and suppressing the change of position at the end point of the sintering. CONSTITUTION:Sintered ores are manufactured by a sintering machine 1 of which an exhaust system for gas-suction is plurally divided in the direction of the machine length. At this time, when the temp. T1 of the system is risen by the increase of the air amt. Q1 in a main air-exhaust machine 9, the air amt. Q2 and temp. T2 in a circulating air-exhaust machine 8 are changed by the amt. equivalent to that of the change of the heat amt. in the exhaust gas of this system. By this method, sintering can be executed by a sintering pattern where the position at the end point of sintering is hardly changed from a base pattern, so that the stabilization of the operation and quality is permitted.

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention controls the exhaust gas temperature of the sintering machine exhaust system without adversely affecting the quality of sintered ore or the operability, and maintains a good equipment environment. The present invention relates to a method for stably producing high-quality sintered ore.

<Prior art and its problems> Currently, the agglomeration of raw material ore used in blast furnaces, etc. is generally performed using a Dwight Lloyd sintering machine. is implemented approximately in the form shown in FIG. That is, in FIG. 2, the sintering compound raw material 3 charged from the hopper 2 to the raw material feeding section of the sintering machine 1 is adjusted in thickness with the cant plate 4, and then ignited from the surface in the ignition furnace 5. The combustion zone 7 is sucked downward by the exhaust fan 6 provided along the moving direction of the raw material storage pallet. Then, the sintering reaction progresses toward the lower layer of the charged material due to the downward ventilation by the exhaust fan 6, and sintering is completed in the entire height direction in the ore discharge section, forming a sintered cake.

By the way, in the above-mentioned sintering work, the gas suction exhaust system for sucking the combustion zone downward is usually divided into multiple parts in the longitudinal direction for the purpose of recovering sensible heat from the sintering machine exhaust gas and reducing the amount of exhaust gas. However, some of the exhaust gas is recirculated. For example, most commonly, the exhaust system is divided into two parts in the longitudinal direction, as schematically shown in Figure 3, and a boiler is installed in the rear exhaust system (where the circulation exhaust fan 8 is installed) to remove exhaust gas. Measures are being taken to recirculate the exhaust gas after recovering the exhaust heat.

However, in such a process, although there is no problem in the exhaust system in the second half where relatively high-temperature exhaust gas is recovered, in the main exhaust system in the first half (where the main exhaust fan 9 is installed), the temperature of the exhaust gas is low. Acid corrosion has been a problem since it tends to deteriorate. In other words, in the main exhaust system, where the temperature of the exhaust gas tends to be lower than that of the exhaust system in the latter half, the exhaust gas temperature may fall below the acid dew point, and as a result, dew condensation and acid adhering to the main exhaust system cause the exhaust gas temperature to drop below the acid dew point. This is because there have been reports that the main exhaust system is subject to corrosion. In addition, in the drawing,
Reference numeral 10.10'' indicates a hood.

Therefore, in order to deal with the above-mentioned corrosion problem, conventionally, the lower target value of the exhaust gas temperature of the main exhaust system was set at a temperature higher than the acid dew point, and the main exhaust air volume was adjusted and the pallet charged with raw materials was Measures have been taken to change the firing completion point (BTP) by adjusting the speed of , thereby controlling the temperature so that the exhaust gas temperature of the main exhaust system satisfies the set value.

That is, the graph shown at the bottom of Fig. 3 is an example of the temperature pattern of the exhaust gas in the sintering machine exhaust system, which is schematically shown at the top, and under steady operating conditions, it takes the base form as shown by the dashed line. shall be.

Here, when the exhaust gas temperature (T1) of the main exhaust system shows a decreasing tendency, if the exhaust air volume (Ql) of the main exhaust system is increased in order to raise the temperature and secure a predetermined temperature, the exhaust gas temperature of the exhaust system becomes the temperature pattern shown by solid line A, and BTP changes to the position of BTP', which is closer to the main exhaust system, and the proportion of high-temperature exhaust gas sucked into the main exhaust system increases, so the exhaust gas temperature in the main exhaust system rises. I will do it. Note that the same effect can be obtained by slowing down the moving speed of the pallet instead of increasing the amount of air exhausted from the main exhaust system.

In this case, it was considered that raising the exhaust gas temperature more than necessary was a waste of electric power for the exhaust fan and should be avoided since it would also reduce the amount of exhaust heat recovered.

However, since the exhaust gas temperature in the main exhaust system is sensitive to changes in outside temperature and air leakage in the main exhaust system, it was necessary to adjust the temperature relatively frequently. It has become clear that if the BTP position is changed as described above in order to maintain the same, the fluctuation range of the operation will not only increase, but also the quality fluctuation of the sintered ore will also increase, which is not desirable.

Therefore, the main purpose of the present invention is to solve the above-mentioned problems pointed out in the production of sintered ore, and to control the exhaust gas temperature at a constant level while suppressing fluctuations in operating conditions and sintered ore quality as much as possible. The object of the present invention is to provide a means for stably producing high-quality sintered ore while maintaining a suitable equipment environment.

<Means for Solving the Problems> The present inventors conducted intensive research from various viewpoints in order to achieve the above object, and found that [In a sintering machine in which the exhaust system for gas suction is divided into multiple parts in the machine length direction] In this case, when the main exhaust gas temperature is increased by increasing the air volume of the main exhaust system, the fluctuation of the BTP position can be suppressed by lowering the air volume and temperature of the circulating exhaust system by the corresponding amount of heat, and the exhaust gas temperature of the main exhaust system can be reduced. They came to the conclusion that sintered ore of good quality can be obtained under stable operating conditions while maintaining the specified value.

The present invention has been made based on the above-mentioned findings and the like. By adjusting the air volume of the circulation exhaust fan in response to air volume fluctuations and performing firing while suppressing BTP position fluctuations, we can produce sintered ore of stable quality with good workability while maintaining a good equipment environment. It is characterized by the fact that it has been made possible to

That is, the present invention measures the exhaust gas temperature of each part of the exhaust system during steady state of a sintering machine having an exhaust system divided into a plurality of parts in the longitudinal direction, and grasps the exhaust gas temperature pattern at that time.
If there are signs of fluctuations in the exhaust gas temperature in the main exhaust system, adjust the suction air volume of the sintering machine main exhaust fan, and adjust the suction air volume of the main exhaust fan and the circulation exhaust fan suction air volume ratio to increase the temperature. The present invention is intended to stabilize the quality of sintered ore by keeping the exhaust gas temperature of the main exhaust system constant while substantially maintaining the pattern.Hereinafter, the present invention will be explained with reference to FIG. 1.

Figure 1 is an explanatory diagram showing an example of application of the method of the present invention using a sintering machine in which the exhaust system is divided into two in the machine length direction. The most effective and simple way to achieve this is to increase the air volume (Q), but in this case, as mentioned above, the firing temperature pattern (exhaust system (exhaust gas temperature pattern), and the BTP position changes.

However, even in the case where the temperature of the main exhaust fan 9 system is increased by increasing the air volume (Ql) of the main exhaust fan 9 system, according to the present invention, the change is equivalent to the change in exhaust gas heat amount of the exhaust fan 9 system) Air volume (Ch) of circulation exhaust fan 8 system.

By changing the temperature (T2), i.e. ΔT2×ΔQ
2' (ΔT1×ΔQl), by adjusting the air volume of the circulation exhaust fan 8, as shown in FIG.
This means that sintering can be carried out with a sintering temperature pattern (exhaust gas temperature pattern from the exhaust system) such as this, making it possible to stabilize operations and quality.

Next, the present invention will be specifically explained using examples.

<Example> Dwight Lloyd type, as schematically shown in Figure 1, in which the exhaust system with a length of 60 m is divided into two parts at a ratio of 5:1, exhaust heat is recovered from the exhaust gas sucked into the latter half by the boiler, and then recirculated. Sintering experiments of fine iron ore were conducted using a sintering machine under various exhaust conditions.

In addition, since the dew point of the exhaust gas in this case is approximately 65°C,
In order to control the temperature of each part of the main exhaust system above that level, it was necessary to control the exhaust gas temperature at 85° C. in the nine main exhaust fans.

In this way, the exhaust gas temperature at the main exhaust fan 9 is set at 85℃.
Table 1 shows the operating conditions when calcination of fine iron ore was carried out while maintaining the following conditions.

Table 1 In Table 1, ``Base'' refers to steady state operation, and ``Conventional method'' refers to only increasing the main exhaust air volume.
In the case where the exhaust gas temperature in the population is maintained at a predetermined value, the "method of the present invention" is ΔT2×ΔQz= (ΔT, XΔ
This means the case where the exhaust gas temperature at the main exhaust fan 9 is maintained at a predetermined value by adjusting the exhaust conditions according to the relationship Q l ).

As is clear from the results shown in Table 1, in the conventional method, the reduction and powdering properties are improved due to the movement of BTP (increased firing speed), but the rotational strength is reduced, and the power consumption of the exhaust fan is reduced. It can be seen that it increases.

On the other hand, it can be confirmed that the method of the present invention has brought about good results in which the BTP position is almost constant, there is little change in the quality of the sintered ore, and the amount of electricity used is also almost constant.

<Summary of Effects> As explained above, according to the present invention, the exhaust gas temperature in the main exhaust system can be maintained at a constant value without impairing the stability of operation or product quality, and acid corrosion in the exhaust system can be effectively suppressed. However, industrially useful effects are brought about, such as making it possible to stably produce high-quality sintered ore at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of application of the method of the present invention using a sintering machine in which the exhaust system is divided into two in the longitudinal direction. FIG. 2 is a conceptual diagram showing the sintering operation status using the Dwight Lloyd sintering machine. FIG. 3 is an explanatory diagram showing an example of application of the conventional method using a sintering machine in which the exhaust system is divided into two in the longitudinal direction. In the drawings: 1...Sintering machine, 2...Hopper. 3...Sintering compound raw material, 4...Cuff) plate. 5... Ignition furnace, 6... Exhaust fan. 7... Combustion zone, 8... Circulation exhaust fan. 9... Main exhaust fan, 10.10'... Hood.

Claims (1)

[Claims] When producing sintered ore using a sintering machine in which the exhaust system for gas suction is divided into multiple parts in the machine length direction, the air volume of the circulation exhaust fan is adjusted in response to fluctuations in the exhaust air volume of the sintering machine's main exhaust system. A method for producing sintered ore, characterized by performing firing while suppressing positional fluctuations of the firing completion point.