JPS61153213A - Pretreatment of powder to be blown in to blast furnace - Google Patents

Abstract

PURPOSE:To maintain the stable supply rate of the powder to a device for blowing the powder into a blast furnace by adjusting the amt. of the combustion gas in a heat generating furnace in accordance with a mill outlet temp. for the moisture fluctuation of a pulverous powder raw material which is fed out at a specified rate and is pulverized by a pulverizing mill. CONSTITUTION:The burner of a hot air generating furnace 7 is ignited while a blower 8 is started in an installation for producing pulverized coal. The temp. is increased up to the temp. necessary for drying of coal (about 200 deg.C at the mill inlet and 90 deg.C at a bag outlet) necessary for drying of coal and the operation is executed only under the control 12 of the mill inlet temp. during this time. The temp. control of the bag outlet 20 or mill outlet 19 is cascaded after the temp. near the above-mentioned temp. is attained and thereafter the control method of this invention is started. The charging of the coal is started where the stability is attained. The charging rate thereof is freely set by the number of revolution of a conveyor 2 for feeding the material at a constant rate to the pulverizing mill 3 so that the substantial follow-up with this control is accomplished even when the setting of the feeding changes. The stable pretreatment of the pulverized powder to be blown to the blast furnace is thus executed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to cutting, crushing, and drying pretreatment of powder and granules (hereinafter simply referred to as "powder") that are blown in from the tuyere of a blast furnace. It's about technology.・(Conventional technology) In recent blast furnace operations, various powders such as pulverized coal and iron ore powder are injected together with blast air through the tuyeres in order to properly manage reaction factors in the furnace or as an alternative fuel to coke. Therefore, powder blowing equipment is equipped with pre-treatment equipment for cutting, crushing, and drying.The pre-treatment equipment for powder is as follows. The device is configured.

A typical example is shown in FIG. 4, where a lumpy raw material 1 containing a large amount of water is fed from a cutting conveyor 2 to a grinding mill 8. This raw material is not only pulverized but also dried to a moisture content of approximately 2% or less;
oo”o high temperature gas is required.For example, JP-A-57
Opened as No.-145908.

In the case of a blast furnace equipped with powder injection equipment, the waste gas 4 from the hot blast furnace has a certain amount of heat at around 100'C, so this is used to combine combustible gas and air 6.
A hot air generating furnace 7 with a burner for mixed combustion produces high-temperature gas.This gas is sucked by a blower 8 and sent to a grinding mill 8, thereby drying the raw material. The pulverized raw material is transported in an air current, collected by a cyclone 9 and a bag filter 10, and supplied to a powder blowing device.

In the conventional processes of raw material cutting, crushing, and drying as described above, in order to keep the load on the crushing mill constant, the rotation speed of the cutting conveyor 2 is controlled so that the differential pressure of the mill is constant, and the amount of crushing is controlled. He took a method to adjust the In addition, the temperature of the high-temperature gas 1 from the hot-air generator 7 is generally controlled by adjusting the amount of combustion gas in the hot-air generator 7 and the ratio with the mixed air so that the temperature 12 at the mill inlet remains constant. Ta.

(Problems to be Solved by the Invention) In the conventional method of keeping the mill load constant, in order to adjust the rotation speed of the conveyor 2 by 1 degree from cutting, 1 degree from raw material supply to 1 degree crushing,
The problem is that the amount of powder produced in the pretreatment equipment leading to storage fluctuates, making it impossible to stably supply the powder to the powder injection device, which in turn causes a major disturbance to the stable powder injection into the blast furnace. was there. Furthermore, there are fluctuations in the moisture and other properties of the raw material to be crushed, so if only the inlet temperature of the grinding mill is controlled, the temperature after the grinding mill will fluctuate significantly. For example, if the temperature is low, the dew point may be 50 to 60. ``When condensation occurs in hot air furnace waste gas with a high C content and the temperature is high, it is especially difficult to produce pulverized coal.
There were also safety issues such as the first explosion when building the f.

Figure 8 shows the changes in the mill outlet temperature, the amount of combustion gas in the hot air generator, and the amount of raw material supplied to the grinding mill when the moisture content of the raw material increases. It can be seen that 1) (Means for solving the problems) The present invention uses the following means to solve the above-mentioned problems.

First, the rotation speed of the cut-out conveyor for supplying raw materials to the grinding mill is made independent of the control system of the grinding mill, and manual setting 2. .

In addition, a temperature measuring device at the outlet of the grinding mill and/or outlet of the bag filter is installed to measure temperature fluctuations due to load fluctuations such as moisture in the raw material. The amount of combustion gas in the generating furnace is adjusted and absorbed.Furthermore, the temperature control at the outlet of the grinding mill is cascaded with the loop of the temperature control at the inlet of the grinding mill. In other words, in order to solve the above-mentioned problems, the present invention aims to change the temperature and cooling by changing the temperature at the mill inlet alone.That is, in order to solve the above problems, the present invention is designed to transfer the bulk raw material for powder to be blown into the blast furnace through the tuyere into the blast furnace using a cutting conveyor. The pulverized fine powder raw material is dried with blast furnace hot air waste gas and high temperature gas generated in the hot air generating furnace 15 that reheats it, and then collected with a collector. When preparing blown powder/granules for blast furnaces, the bulk raw material to be crushed is cut out in a fixed amount regardless of its moisture content and properties, while the amount of combustion gas from the hot air generating furnace is adjusted to the mill inlet temperature. By controlling the outlet temperature of the grinding mill or the outlet temperature of the collector, which is cascade-controlled based on the We propose a pretreatment method for blast furnace blown powder, which is characterized by pretreatment.

(Function) As shown in FIG. 1, in the method of the present invention, the quantitative cutting conveyor supplied by the crushing mill 1 is used 20 times t.

The rotation speed of the variable speed motor is made to follow the rotation speed set by the manually set hand controller 18. Thermometers are installed at eight locations: the mill inlet 21, the mill outlet 19, and the bag filter outlet 20, and a mill inlet temperature control loop 12 enables local control. The temperature control loop 1 at the mill outlet 8 or bag filter 10 outlet is cascaded so that temperature fluctuations at the mill outlet or bag filter outlet are absorbed by the amount of combustion gas. In the illustrated example, the mill outlet and the bag filter 2. )
The temperature at the outlet can be changed to determine the ratio between the amount of combustion gas and the amount of air and the respective flow rates, and the ratio can be fixed or it can follow the fluctuations of the combustion gas calories. (Embodiment) An embodiment of the present invention will be described below using equipment for injecting pulverized coal into a blast furnace.

In the pulverized coal production equipment, the first thing to do is blower g+ as shown in Figure 1.

After starting up, the burner of the hot air generating furnace 7 was ignited.

After ignition, the temperature required for drying the coal (200℃ at the mill entrance)
The temperature was raised to approximately 90°C at the bag outlet, but during that time the mill was operated only with the mill inlet temperature control 12. After reaching near the above temperature, the control method of the present invention was started by cascading temperature control at the bag outlet IX port (20) or the mill outlet (19).

When the coal is stabilized, start feeding the coal.1 The amount of coal fed into the grinding mill 8 can be freely set at a constant speed of 20 revolutions on the cutting conveyor, even when the cutting settings change! ...This control can adequately follow. In this way, stable pretreatment of pulverized coal for injection into the blast furnace 1 was achieved.

The fuel used in the hot air generating furnace was M gas (C gas may also be used), which is a mixture of B gas from a blast furnace and C gas from a coke oven.

(Effects of the Invention) As explained above, according to the present invention, it is possible to adjust a constant amount of blown powder while absorbing load fluctuations such as the moisture value of the lumpy raw material by the amount of combustible gas burned in the hot air generating furnace. Because you can
It is possible to achieve stable supply of powder to the powder injection device (1), and even stable powder injection to the blast furnace. Furthermore, by controlling the temperature at the outlet of the collector and the outlet of the grinding mill, it is possible to avoid risks such as condensation of hot blast furnace waste gas and initial explosion in the case of pulverized coal. Figure 2 is an example of this, showing the changes in the mill outlet temperature, the amount of combustion gas in the hot air generator, and the amount of raw material supplied to the mill when the moisture content 1j of the raw material increases, but when compared with Figure 8, Mill supply is stable.

Moreover, according to the present invention, for moisture fluctuation, Mid-C?
) By adjusting the amount of combustion gas in the hot blast furnace based on the blast temperature, it is possible to maintain a stable supply amount to the powder injection device into the blast furnace. Since temperature is also controlled, it is now possible to prevent condensation of exhaust gas and dust explosions.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram of the control flow of the pretreatment method of the present invention, and FIG. 2 is a graph showing the effects of the embodiment of the method of the present invention.
10 FIG. 8 is a graph showing the effect of the embodiment of the prior art. FIG. 4 is a control flow diagram of the prior art. 01... Lump raw material 2... Hanging conveyor 8... Grinding mill 4...Hot air furnace waste gas 5...Flammable gas 6...Combustion air 7...Hot air generator
8...Blower-9...Cyclone 10
... Bag filter 11 ... Mill differential pressure control loop 12 ... Mill inlet temperature control loop 13 ... Combustion gas flow rate setting device 14 ... Powder injection device 15 ... Blast furnace 16 ... Chimney 1st floor...
Mill (Bag filter outlet temperature control loop 18... Cutting conveyor rotation speed control 19... Mill outlet thermometer 20... Bag filter outlet thermometer 21... Mill inlet thermometer

Claims (1)

[Scope of Claims] 1. The bulk raw material for powder to be blown into the furnace through the tuyere of the blast furnace is cut out using a cutting conveyor and then pulverized by a grinding mill, and the pulverized fine powder raw material is disposed of in the blast furnace hot air blast furnace. The lumpy raw material to be crushed when preparing blown powder/granules for blast furnaces by drying gas and high-temperature gas generated in a hot air generating furnace and then collecting it in a collector. The amount of combustion gas from the hot air generating furnace is controlled in cascade based on the mill inlet temperature, and the outlet temperature of the crushing mill or collector outlet temperature is kept constant. Pretreatment of blown powder for blast furnaces, which is characterized by pretreatment while absorbing in-line temperature fluctuations caused by fluctuations in moisture, properties, and input amount of raw material powder. Method.