JPH09209010A - Abnormality detection method of carrier gas in powder transportation equipment - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a technique for rapidly and easily detecting the occurrence of an abnormal flow of a carrier gas for each pipe by the temperature change on the surface of the transport pipe. SOLUTION: A carrier gas is joined in the middle of an injection tank holding powder pulverized in a hot air dry state and a transportation pipe provided between a plurality of blowing tuyere, and the powder is blown into a device to be blown. At this time, in the transportation pipe, the time change of the surface temperature on the injection tank side from the carrier gas confluence point is measured, and the generation of the gas flow to the tank side is determined by the magnitude of the measured value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a carrier gas in powder transportation equipment, and more particularly to an effective technique for blowing pulverized coal into a blast furnace.

[0002]

2. Description of the Related Art An example of a pulverized coal blowing facility into a blast furnace is shown in FIG. The pulverized coal pulverized by the coal pulverizer 1 sequentially passes through the recovery bag / filter 2, the pulverized coal hopper 3, and the intermediate tank 4 and is finally transported to the injection tank 5. Since the injection tank 5 is constantly pressurized with gas to a pressure higher than that in the blast furnace,
The pulverized coal is blown into the blast furnace 8 through the transportation pipe 6 connected to a large number of tuyere 9 arranged around the furnace of the blast furnace 8. At that time, since the gas pressure of the injection tank 5 is not sufficient, the carrier gas 7 for carrying the pulverized coal is joined in the middle of the transportation pipe 6 so that the blowing amount in the circumferential direction of the furnace becomes uniform. ing. Air is used as the carrier gas 7 from the viewpoint of blowing cost.

By the way, these pulverized coals usually have a diameter of 74 μm.
Although those having a diameter of m or less are used, the solid-gas ratio may change due to fluctuations in the internal pressure of the blast furnace and the transportation pipe 6 may be clogged. In such a case, as shown in FIG. 6, the carrier gas 7 merged from the middle flows toward the injection tank 5 (hereinafter referred to as an abnormal or abnormal flow 14 because the flow is abnormal), thereby increasing the oxygen concentration therein. There was a risk of dust explosion. Therefore, conventionally, this increase in oxygen concentration is detected by using the oxygen concentration meter 10 as a sensor, and the carrier gas 7
The presence or absence of the above abnormality was judged. Then, if there is an abnormality, the work for clearing the clogging 15 is immediately performed to restore the normal blowing. However, in the method of detecting the oxygen concentration, even if the oxygen concentration meter 10 is installed in the injection tank 5 and even if the increase in the oxygen concentration due to the abnormal flow 14 of the carrier gas 7 can be detected, a plurality of connected transports are used. It is not possible to identify which of the pipes 6 the transport pipe 6 is clogged with. Further, since the carrier gas 7 has already flowed into the injection tank 5 at the time when the increase in the oxygen concentration is detected, there is a time delay between the occurrence of the abnormal flow 14 and the detection of the increase in the oxygen concentration. Can not be ignored, and clogging of transport piping 6 1
There was a problem that the judgment was delayed.

On the other hand, Japanese Patent Laid-Open No. 3-2304 discloses a pulverized coal injection facility for a blast furnace having a structure different from that described above.
“A thermometer is installed at each required position of the piping between the secondary distributor of pulverized coal (corresponding to the above-mentioned injection tank) and the tuyere of the blast furnace, and the temperature of each distribution pipe is monitored to block the distribution pipe. Detecting '. In this method, since coal is pulverized in a coal mill while being dried with hot air, the pulverized coal has a considerable temperature (about 80 ° C.). The focus is on decreasing.

However, since this method does not have a structure for introducing the carrier gas into the pipe between the secondary distributor and the tuyere of the blast furnace, there is no problem due to the above-mentioned abnormal flow. Therefore, the determination of the clogging time does not need to be made so quickly in time, and therefore the determination is made only by the change in the absolute value of the pipe surface temperature, and the determination is slow.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a technique for promptly and easily detecting an abnormal flow of a carrier gas for each pipe due to a temperature change on the surface of the pipe. There is.

[0007]

In order to achieve the above-mentioned object, the inventor has found that, in a large number of transportation pipes connecting an injection tank and tuyere of a blast furnace, a carrier gas flows to the tank side as an abnormal flow. The inventors have keenly studied to attach the surface thermometers and to detect the occurrence of the abnormal flow quickly and easily based on the measured values. as a result,
The temperature of the carrier gas that joins the transportation pipe is approximately 10 to 20 ° C.
Therefore, it was confirmed that the abnormal flow generation of the carrier gas can be accurately detected by capturing the temperature change on the surface of the pipe where the abnormal flow occurs, and the present invention has been completed. That is, the present invention, a carrier gas is merged in the middle of a transportation pipe provided between an injection tank holding a powder pulverized in a hot air dry state and a plurality of blowing tuyere, and the powder is blown into a device to be blown. At the time of blowing, measuring the time change of the surface temperature on the injection tank side from the carrier gas confluence point in the transportation pipe, and determining the occurrence of gas flow to the tank side by the magnitude of the measured value. This is a method for detecting an abnormality of a carrier gas in a characteristic powder transportation facility.
Further, the present invention is a method for detecting an abnormality of a carrier gas in a powder transportation facility, wherein the surface temperature is a temperature change value according to the following formula.

ΔT = T _i −T _in (1) n = C · S where ΔT: temperature change value (° C.) T _i : current temperature (° C.) T _in : temperature (° C.) n seconds before the present n: change interval (second) C: sample period (-) S: integer (-) Furthermore, the present invention is characterized in that the above powder is pulverized coal and the above-mentioned blow target device is a blast furnace. It is also a method of detecting an abnormality in the carrier gas in.

If the present invention described above is adopted, a change in the surface temperature of each transportation pipe can be detected, and the time delay associated with the detection can be eliminated. In addition, the clogging of the transportation pipe can be removed easily and quickly.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing a transportation piping system in a pulverized coal blowing facility of a blast furnace that employs the carrier gas abnormality detection method according to the present invention. Although FIG. 1 shows the case where three transportation pipes 6 are provided from the injection tank 5 to the tuyere 9 of the blast furnace 8, at least 30 pipes are actually arranged around the furnace of the blast furnace 8. Here, a so-called sheath thermometer 11 was experimentally installed on the three transportation pipes 6 and further on the injection tank 5 side from the confluence point 13 of the carrier gas 7, and artificial clogging was caused to occur at the installation positions. The surface temperature change of was investigated. As shown in FIG. 2, the thermometer 11 was welded so that its sheath portion was wound around the surface of the transportation pipe 6 and covered with a heat insulating material 16. The reason is that the surface temperature that is not affected by the outside air can be measured by winding, and that if the temperature of the carrier gas 7 is measured by directly inserting the thermometer 11 into the transport pipe 6, the temperature can be measured by the powder flow transported. This is because it is taken into consideration that the total 11 is damaged and measurement cannot be performed immediately.

Then, a temporary pulverized coal clogging was generated by closing a manual valve before the tuyere 9 of the blast furnace 8 and the temperature change on the surface of the transportation pipe 9 was measured. The result is shown in FIG.
Shown in As is apparent from FIG. 3, immediately after the occurrence of clogging (valve closed, symbol A), the surface temperature begins to gradually decrease and converges to a certain temperature after 3 minutes (symbol B). From this experimental result, if the thermometer 11 is attached to the surface of the portion of the transport pipe 6 where the abnormal flow 14 is generated in the carrier gas 7, the abnormal temperature of the carrier gas 14 due to the blockage of the transport pipe 6 is caused by the temperature change. Moreover, it has been clarified that it can be detected for each of a large number of transportation pipes 6. However, the powder to be transported must be kept warm,
It is dehumidified powder, and between the powder itself and the carrier gas,
It requires a certain absolute temperature difference.

However, FIG. 3 shows changes in the absolute value of the temperature. Although this absolute value can be used to judge abnormal flow of carrier gas,
In order to make an accurate judgment, it is necessary to wait until the temperature converges to the above-mentioned constant temperature, or to temporarily set the temperature at which the abnormal flow occurs as the temperature from experience. In other words, it takes time to judge the occurrence of abnormal flow in any of the methods. Therefore, as shown in FIG. 4, the inventor has adopted a temperature change value obtained by processing the absolute value of the temperature by the formula (1) to speed up the determination. In FIG. 4, the time from when the valve is closed to artificially generate the clogging to when the clogging is detected is Ta and Tb. Here, Ta is the detection time based on the temperature change value, and Tb is the detection time based on the absolute temperature value. Comparing the two, Ta is clearly smaller than Tb. From this, it can be understood that the detection based on the temperature change value is superior in the detection speed to the detection based on the absolute value. Further, in this method, since the thermometer is covered with the heat insulating material, the variation in the surface temperature of each transportation pipe is not affected by the seasonal variation, and the detection threshold value is very easy to set.

FIG. 7 shows an example of detection by the above temperature change value when an abnormal flow actually flows. In this case, the sample period C is 5 seconds and the integer S is 36. When a clogging occurs in the transportation pipe, the absolute value of the temperature gradually decreases, but the temperature change value accurately catches the timing when the temperature drops compared to the absolute value, and the clogging is clearly detected. . Also,
It is also clear that the detection speed is about 5 minutes faster than the absolute value detection.

The above embodiment has been described in the case where the powder is pulverized coal and the equipment to be blown is the blast furnace, but in the present invention, the carrier gas is blown into the injection tank such as solid fuel supply to the heating burner. Any powder transport facility can be applied as long as it merges in the middle of the pipe connecting the lances.

[0015]

As described above, according to the present invention, the reverse flow of the carrier gas due to the clogging of the powder transport pipe can be detected early by the measurement of the thermometer attached to the surface of the transport pipe. It was Also, if thermometers are attached to all the transportation pipes from the injection tank, clogging can be cleared quickly.

[Brief description of drawings]

FIG. 1 is a view showing a pulverized coal blowing facility in which a carrier gas abnormality detection method according to the present invention is implemented.

FIG. 2 is a diagram showing installation of a thermometer in a powder transportation pipe.

FIG. 3 is a diagram showing changes over time in surface temperatures of three transportation pipes.

FIG. 4 is a diagram illustrating a change in surface temperature.

FIG. 5 is a diagram showing a pulverized coal blowing facility and a transportation piping system of a blast furnace.

FIG. 6 is a diagram illustrating the occurrence of an abnormal flow of carrier gas.

FIG. 7 is a diagram showing an abnormality detection situation when the surface temperature is processed by a temperature change value.

[Explanation of symbols]

 1 coal crusher 2 bag / filter 3 pulverized coal hopper 4 intermediate tank 5 injection tank 6 transportation pipe 7 carrier gas 8 blast furnace 9 tuyere 10 oxygen concentration meter 11 sheath thermometer 12 recorder 13 confluence point 14 abnormal flow 15 clogging 16 Heat insulating material

Claims (3)

[Claims] 1. A carrier gas is merged in the middle of an injection tank holding powder pulverized in a hot-air dried state and a transportation pipe provided between a plurality of blowing tuyere, and the powder is blown into a device to be blown. When inserting, the time variation of the surface temperature of the injection tank side from the carrier gas merging point in the transportation pipe is measured, and the generation of the gas flow to the tank side is determined by the magnitude of the measured value. A method for detecting abnormality of carrier gas in powder transportation equipment. 2. A method for detecting an abnormality of a carrier gas in a powder transportation facility, wherein the surface temperature is a temperature change value according to the following formula. ΔT = T _i −T _in (1) n = C · S where ΔT: temperature change value (° C.) T _i : current temperature (° C.) T _in : temperature (° C.) n seconds before the current time n: change Interval (sec) C: Sample period (-) S: Integer (-) 3. The method for detecting an abnormality of a carrier gas in a powder transportation facility according to claim 1, wherein the powder is pulverized coal and the apparatus to be blown is a blast furnace.