JPH01191710A - Operation of blast furnace - Google Patents

Abstract

PURPOSE:To reduce fuel ratio and to continue the stable operation of a blast furnace by varying the drum strength of coke to be charged in accordance with information on the distribution of the heat history of granular coke collected from the level of a tuyere. CONSTITUTION:Granular coke is collected from a raceway at the end of a blast tuyere of a blast furnace and the distribution of the heat history of each granule is examined by laser Raman spectroscopic analysis or other method. The percentage of granules at >=1,200 deg.C in the distribution of the heat history is calculated, the drum strength of coke to be charged is selected from the relation between the rate of powder and pressure drop so as to make the coke fit for operation and the blast furnace is operated. Pressure drop in the lower part of the furnace is suppressed and stable operation can be continued.

Description

[Detailed description of the invention] "Purpose of invention" (Industrial application field) This invention relates to a method of operating a blast furnace.

(Conventional technology) Conventionally, the method of collecting coke in a blast furnace and investigating the thermal history of the coke was to adjust the particle size of the sample, and then decalcify it with hydrofluoric acid or hydrochloric acid for about a week. Thereafter, there was a method of measuring crystallites LC (002), La (110), etc. by X-ray diffraction, which took about 30 minutes. However, as mentioned above, it takes a long time from preparation to measurement to know the thermal history of a single point of coke.
There was no concept of understanding the thermal history of coke particles as a sample group as a distribution. Therefore, there has been no attempt to utilize the distribution of the thermal history of coke in the tuyere raceway as a means of in-furnace analysis.

(Problems to be Solved by the Invention) As mentioned above, the measurement method using X-ray diffraction requires a long time to prepare and measure the sample. However, there was a fatal flaw in that it was not possible to obtain data as a sample group for use in in-core analysis.

The present invention is based on the knowledge of our predecessors that the scattering spectrum of graphite structures measured in laser Raman spectroscopy is highly dependent on temperature. This invention was created as a specific blast furnace operating method in conjunction with the completion of the invention of a method for estimating the distribution of thermal history of coke in a blast furnace that enables point measurement. It is an object of the present invention to provide a blast furnace operating method that selects and uses charged coke with a DI (%) that matches the operating conditions based on the distribution of the thermal history of the coke described above.

"Structure of the Invention" (Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventors have developed a method for analyzing 200% of the thermal history distribution of pulverulent coke collected from the tuyere level.
We propose a blast furnace operating method characterized by changing the drum strength of charged coke depending on the proportion of particles with a temperature of 0°C or higher.

(Function) In carrying out the present invention, it is first necessary to sample the pulverulent coke in the tuyere end raceway and to know the distribution of thermal history of each particle in a short time. For this purpose, the degree of graphitization can be measured from the intensity ratio of scattering spectra 1360e11-' and 1580-' by laser Raman spectroscopy with a multi-channel detector. This degree of graphitization is highly correlated with the thermal history of coke. Since the degree of graphitization is quantified by a computer, it is possible to obtain information as a distribution of thermal history using simple software.

FIG. 4 shows the relationship between the degree of graphitization (R value) and the thermal history temperature (macro measurement).

Figure 2 shows the thermal history distribution of powdered coke sampled at the grain level, with the vertical axis representing the incidence of powder of 3 or less particles and the horizontal axis representing
This is the proportion of temperatures above 00°C. D1%9
When examining the 30% powder ratio line for the three stages of 0.95.98, it can be seen that the lower the DI, the lower the proportion of particles with a thermal history of 2000° C. or higher. or,
At DI = 95%, the powder ratio increases rapidly when the proportion of particles above 2000℃ exceeds 40%, and the critical point is different for each DI, and the proportion of particles above 2000℃ is extremely important. I understand that.

In FIG. 3, the vertical axis shows the pressure drop in the lower part of the furnace, and the horizontal axis shows the powder rate of 3 ms or less for each DI. It can be seen that when the powder ratio reaches 30% at DI=95%, the pressure loss increases rapidly. Furthermore, it is clearly shown that the critical point at which this pressure drop suddenly changes varies depending on the DI. .

In FIG. 1, the vertical axis shows the DI (%) of the charged coke, and the horizontal axis shows the proportion of particles of 2000° C. or higher in the thermal history distribution of the pulverulent coke sampled from the tuyere level. Therefore, in blast furnace operation, the pressure drop in the lower part of the furnace is 1.2
Since it is necessary to keep it to about kg/cd, Fig. 2,
The DI (%) suitable for the operation can be selected from the relationship shown in FIG.

(Example) 1. An example in a blast furnace with a furnace capacity of 4000 ryf will be described.

The operating conditions were a fuel ratio of 517 kg/T, charged coke DI (
%) 95, the average value of the thermal history distribution of the pulverulent coke collected from the grain level is 1680°C, and 2
Since the proportion of particles above 000°C was 26%,
Instructions were given to the single continuous coke plant to change the DI (%) of the charged coke to 94, and the new formulation was started the next day. Six hours after switching to the new formulation, the proportion of thermal particles of 2000℃ or higher in the pulverulent coke at the tuyere level was 2.
The incidence was 0%.

2. Conventionally, the DI (%) of charged coke was constant, but depending on the situation in the lower part of the furnace, the DI (%) was adjusted to suit the operation.
) By using the coke of 2000, an improvement in the variation of the furnace condition score (pressure loss in the lower part of the furnace, number of slip rack hangings) from 60 to 90 points to 80 to 90 points was obtained when averaged over one month.

"Effects of the Invention" As detailed above, by the method of the present invention, the proportion of particles with a temperature of 2000°C or higher in the thermal history distribution of coke particles collected from the tuyere level was determined, and the relationship between the powder ratio and pressure loss was determined.
Since the DI (%) of charged coke suitable for the operation can be selected from the relationship of DI (%) in the case of %, stable operation with a low fuel ratio can be continued.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the proportion of particles with a temperature of 2000°C or higher in the thermal history distribution of coke powder at the tuyere level obtained by the present invention and DI (%), and Figure 2 shows the relationship between the powder ratio and the thermal history temperature. The ratio of particles of 2000"C or more is shown. FIG. 3 is a chart showing the relationship between the pressure drop in the lower part of the furnace and the powder ratio, and FIG. 4 is a chart showing the relationship between the degree of graphitization of coke and the thermal history temperature.

Claims (1)

[Claims] A blast furnace operating method characterized in that the drum strength of charged coke is changed depending on the proportion of particles of 2000° C. or higher in the thermal history distribution of pulverulent coke collected from the tuyere level.