JP2018204076A - Estimation method of burning rate of reduction material injected in blast furnace, operation method of blast furnace and blowing tuyere - Google Patents

Abstract

To realize a stable operation of a blast furnace by accurately estimating and utilizing the burning rate of an injected reduction material in the blast furnace operation in which the reducing material is blown into the furnace.SOLUTION: In the blast furnace operation, a reduction material is blown into the furnace through a blowing pipe in which a tip portion is located in a blowing flow path of the blower tuyere body or a blowing pipe path of a blowpipe upstream side of the blower tuyere. Emission peak intensity of a radical of the reduction material is measured in the burning field through an observation hole provided in the blower tuyere body or the blowpipe. The obtained emission peak intensity is compared with a calibration curve representing the relationship between the burning rate of the reduction material and the emission peak intensity of the radical in the burning field. The burning rate of the reduction material is thus estimated from the measured emission peak intensity of the radical in the burning field.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for estimating the combustion rate of a blast furnace blowing reductant that can accurately estimate the combustion rate of the blown reducing material in a blast furnace operation in which the reductant is blown into the furnace.
The present invention also relates to a blast furnace operation method for achieving stable operation of the blast furnace by utilizing the above-described method for estimating the combustion rate of the blast furnace blown reducing material.
Furthermore, the present invention relates to a ventilation tuyere suitable for use in the implementation of the blast furnace operating method described above.

Currently, in blast furnace operation, for the purpose of reducing the amount of coke used, an operation of blowing a reducing material from a blower tuyere is being carried out.
In such blast furnace operation, the reducing material blown from the ventilation tuyere includes fossil fuels such as pulverized coal, natural gas, propane gas, heavy oil, light oil, tar, vegetable oils including rapeseed oil, coke oven gas and Examples include plastic waste. These reducing materials are blown into a hot air flow path through a blowing pipe called a lance inserted into a blowing tuyere composed of a blow pipe and a blowing tuyere body, and are supplied into the blast furnace furnace together with hot air.

The reducing material supplied into the blast furnace is combusted in the raceway section formed in the blower tuyere and at the tip of the tuyere, and serves as a substitute for coke in terms of maintaining heat at the bottom of the blast furnace and reducing iron oxide. However, since the air flow velocity is very fast at 200 m per second, the time from when the reducing material is blown into the air blower tuyeres through the raceway and entering the packed bed in the furnace is as short as several milliseconds.
Therefore, when the amount of reducing material to be injected is increased in order to further reduce the amount of coke used, the reducing material that could not be completely combusted in the raceway (hereinafter referred to as unburned char) is filled in the furnace. In some cases and remained in the furnace.

Part of the unburned char remaining in the furnace is consumed by the solution loss reaction, but its consumption is limited, so some of the unburned char that remains unconsumed is discharged from the top of the furnace. This leads to a reduction in the coke replacement rate, which leads to an increase in the reducing material ratio. Some of them accumulate in the furnace core and dripping zone and cause deterioration in the ventilation and liquid permeability in the furnace.
Therefore, in order to maintain a sound blast furnace operation, it is necessary to keep the combustion rate of the reducing material above a certain level.

  For that purpose, it is necessary to grasp the combustion rate of the reducing material inside the blast tuyere where the reducing material burns and in the raceway part, but the inside of the blast furnace tuyere and the raceway part is a high-temperature combustion field exceeding 2000 degrees Celsius. In addition, since the coke, hot metal, slag, etc. also exist in the raceway section, it is extremely difficult to measure the burning rate of the reducing material.

Until now, the following method has been proposed as a method for grasping the combustion behavior of the reducing material represented by the combustion rate.
For example, in Patent Document 1, a temperature is calculated from the brightness of a raceway measured by a radiation temperature camera installed in a ventilation tuyere sight window, a time series data analysis of the temperature is performed, and a power density spectrum is maximized. A method has been proposed in which the raceway decay period is calculated from the reciprocal of the frequency, and the pulverized coal combustion rate is evaluated from the decay period.

  Moreover, in patent document 2, the light emission of the pulverized coal combustion flame is detected from the tip of the sonde installed in the tuyere of the blast furnace, and the light emission is spectroscopically analyzed. A method has been proposed for observing.

  Furthermore, in Patent Document 3, the emission of the combustion field in the raceway is imaged at two different wavelengths from the window behind the blast furnace blast tuyere, and the pixel of the image obtained by digitizing such data is obtained as a histogram by obtaining the temperature from the two color luminances. A method for detecting the furnace condition from the shape of the histogram has been proposed.

In addition, in the fields other than the blast furnace, the following methods have been proposed as methods for measuring the combustion behavior of fuel.
For example, in Patent Document 4, a gas combustion field is divided in a transition piece (TP) in a gas turbine, and light emission from the gas combustion field is detected by a plurality of light receiving portions provided on the inner wall of the TP, and then spectral analysis is performed. The band spectrum intensity is obtained, the average gas temperature of each part of the gas combustion field is calculated based on the combustion attribute of the gas, and the gas temperature of the gas combustion field is calculated from the average gas temperature calculated for each part and the band spectrum intensity. A method for calculating the distribution has been proposed.

JP-A-7-305105 Japanese Patent Laid-Open No. 10-30105 Japanese Patent No. 4873788 JP 2012-193978 A

  However, the method described in Patent Document 1 and Patent Document 3 is a method of estimating the combustion behavior of pulverized coal by measuring the luminance or radiation temperature from the rear viewing window of the blower tuyere.・ Because the gas flow in the tuyere is the same direction, it is difficult to identify the position of the pulverized coal to be measured, and even if the combustion behavior of the pulverized coal can be grasped, the position where the phenomenon occurred cannot be determined There was a point.

  In addition, in the method described in Patent Document 2, it is necessary to insert a sonde from the tuyere to measure the luminescence of the pulverized coal, but if the sonde is inserted into the tuyere, the gas flow in the tuyere is disturbed and the pulverized coal There was a problem that the combustion behavior changed from normal operation. Further, when light emission is measured by inserting a sonde into the raceway from the tuyere, there is a problem that the light emission of pulverized coal cannot be measured correctly due to the influence of hot metal or coke.

Furthermore, in the method described in Patent Document 4, in order to improve the controllability of the combustion temperature of the fuel, a light receiving unit such as an optical fiber is installed on the inner wall of the combustion apparatus, and combustion at a specific position in the combustion apparatus is performed based on the detected light. This is a method for calculating the temperature distribution of the gas and does not match the problem of measuring the burning rate of the reducing material in the blast furnace tuyere.
In addition, in the blow pipe part to the tuyere part, in general, solid reducing material such as pulverized coal may be blown, and foreign matters such as brick fragments dropped from the hot air furnace are burned gas. At the same time, a solid flows through the apparatus. If the light receiving part is installed on the inner wall of the furnace in such an environment, the light receiving part is damaged due to the collision of the flying solid with the light receiving part and the adhesion of the molten flame retardant generated from the blown reducing material. In some cases, it was impossible to detect luminescence. Once it becomes impossible to detect light emission, it is necessary to replace the blowpipe or tuyere, but this requires the operation of the blast furnace to be interrupted, resulting in a reduction in the amount of hot metal produced.

The present invention advantageously solves the above problem, and in the blast furnace operation in which the reducing material is injected, the burning rate estimation of the blast furnace blowing reducing material that can accurately estimate the burning rate of the injected reducing material. It aims to provide a method.
The present invention also provides a blast furnace operation method capable of performing stable operation of the blast furnace by adjusting the operation conditions based on the result obtained by the method of estimating the combustion rate of the blast furnace blown reducing material described above. With the goal.
Furthermore, this invention aims at providing a suitable ventilation tuyere used for implementation of the above-mentioned blast furnace operating method.

That is, the gist configuration of the present invention is as follows.
1. In the blast furnace operation in which the reducing material is blown into the furnace through the blowing pipe whose tip is located in the blowing channel of the blowing tuyere body or the blowing pipe part on the upstream side of the blowing tuyere,
The radical emission peak intensity in the combustion field of the reducing material is measured through an observation hole provided in the tuyere main body or the blow pipe part, and the obtained emission peak intensity is obtained from the reducing material prepared in advance. It is characterized by estimating the burning rate of the reducing material from the measured emission peak intensity of the radical in the combustion field by collating with a calibration curve representing the relationship between the combustion rate and the emission peak intensity of the radical in the combustion field. A method for estimating the combustion rate of blast furnace reducing material.

2. 2. The blast furnace according to 1 above, wherein the reducing material is at least one selected from pulverized coal, natural gas, propane gas, heavy oil, light oil, fossil fuel, vegetable oil, coke oven gas, and waste plastic. A method for estimating the combustion rate of blown reducing material.

3. In blast furnace operation using the method for estimating the combustion rate of the blast furnace blown reducing material according to 1 or 2,
A blast furnace operating method characterized by increasing the oxygen concentration in the blown air by 1 vol% or more when the estimated burning rate of the reducing material falls below 0.95 as a relative value with respect to the burning rate during stable operation.

4). In blast furnace operation using the method for estimating the combustion rate of the blast furnace blown reducing material according to 1 or 2,
A blast furnace operating method characterized in that when the estimated burning rate of the reducing material falls below 0.95 as a relative value with respect to the burning rate during stable operation, the blowing temperature is increased by 20 ° C or more.

5. It has a blowing pipe of a reducing material whose tip is located in the air flow path of either the blower tuyere main body or the blowpipe part upstream of the blower tuyere, and either the blower tuyere main body or the blowpipe part One or both of them have an observation lance that communicates with the inside and outside thereof, and the observation lance has an observation window on the outside of the blower tuyere body or the blow pipe part, and at the other end in the blow passage. Equipped with a luminescence intensity measuring device to measure the emission peak intensity of radicals in the combustion field of the injected reducing material, and in addition, collecting the reducing material to collect the reducing material ejected from the blower tuyere into the blast furnace raceway A blower tuyere characterized by having a device.

According to the present invention, the relationship between the emission peak intensity of radicals generated by the combustion of the reducing material and the combustion rate of the reducing material blown into the blowing tuyere is obtained in advance, and then the radicals in the blowing tuyere are determined. By measuring the emission peak intensity, the burning rate of the reducing material is estimated in a non-contact manner, and the operating conditions are controlled based on this estimated value, so that the burning rate of the reducing material does not interfere with the furnace environment. As a result, more stable blast furnace operation can be performed.
In addition, by measuring the emission intensity of the reducing material combustion field from the outside of the furnace through the observation hole, it is possible to prevent damage to the light receiving part and accurately grasp the reducing material combustion rate without hindering blast furnace operation. .

It is a schematic diagram of a suitable ventilation tuyere used for implementation of this invention. It is a figure which shows the calibration curve created according to this invention. It is a schematic diagram which shows the cross section of a small combustion furnace. It is a figure which shows the calibration curve of the pulverized coal combustion rate created according to this invention. It is the figure which showed the calculation method of a part of emission spectrum of a pulverized coal combustion field, and the emission peak intensity of a radical.

Hereinafter, the present invention will be specifically described.
Since the combustion field of the reducing material blown into the air flow path of the blow pipe part upstream of the air blow tuyere body or air blow tuyere is a high temperature condition exceeding 2000 ° C., radicals that do not exist in the atmosphere or at room temperature are generated. .
The pulverized coal combustion field will be described as an example of the reducing material combustion field. OH, CH, C ₂ radicals derived from the combustion of hydrocarbons in the pulverized coal and Na derived from Na, K contained in the ash content in the pulverized coal. , K radicals are present.
In such a combustion field, a radical is excited by heat or a combustion reaction, and it has been confirmed that when this radical changes from an excited state to a ground state, light having a wavelength unique to the radical is emitted (OH radical). : 309 nm, CH radical: 431 nm, C ₂ radical: 517 nm, Na radical: 589 nm, K radical: 766, 770 nm).

Here, it is considered that the emission peak intensity of radicals has a correlation with the combustion rate of the reducing material because radicals are generated by the combustion of the reducing material.
The present invention makes use of the above correlation to create a calibration curve representing the relationship between the burning rate of the reducing material and the emission peak intensity of the radicals existing in the combustion field in advance, so that the radicals existing in the combustion field. The burning rate of the reducing material is estimated from the emission peak intensity.
In addition, the present invention performs more stable blast furnace operation by changing the operation conditions so as to improve the combustion rate of the reducing material when the estimated value becomes less than a certain level. .

In FIG. 1, an example of a suitable ventilation tuyere used for implementation of this invention is shown.
In the figure, reference numeral 1 is a blower tuyere body, 2 is a blow pipe part connected to the blower tuyere body, 3 is a reducing material blowing pipe, and in this example, the tip of the reducing material blowing pipe 3 is It has shown about the case where it inserts in the ventilation flow path of the ventilation tuyere main body 1. FIG. Numeral 4 is a blast furnace raceway, and 5 is a sampling device for carrying out sampling in the raceway 4 through the blower tuyere body 1. Reference numeral 6 denotes an observation hole that communicates with the inside and outside of the blow pipe portion 2, 7 denotes an observation window provided outside the pipe portion of the observation hole 6, and 8 denotes light emission of radicals in the blower tuyere body 1 at the other end of the observation hole 6. This is a light emission intensity measuring device for measuring peak intensity.

Here, the sampling device 5 may be of any type as long as the reducing material ejected into the raceway can be collected.
In addition, the observation lance hole 6 is installed in the blow pipe portion 2 in FIG. 1, but this point is a position where the emission of the reducing material combustion field in the furnace can be measured in such a way that the position in the flow direction can be specified. If it exists, the installation location does not matter.
Furthermore, as the emission intensity measuring device 8, any spectrometer using an interference filter, one using a diffraction grating, or one using a prism can be used as long as it satisfies the condition that the emission peak intensity of radicals can be calculated. Conforms to any format.

In the present invention, a calibration curve is prepared for various reducing materials by obtaining in advance the relationship between the burning rate and the emission peak intensity of a specific radical.
An example is shown in FIG.
FIG. 2 is a calibration curve created by determining the relationship between the combustion rate and the emission peak intensity of OH radicals using pulverized coal as the reducing material.
As shown in the figure, there is a strong correlation between the burning rate of the reducing material and the emission peak intensity of radicals.
Therefore, the combustion rate of the reducing material is estimated using this calibration curve.

  That is, when performing a blast furnace operation in which a reducing material is blown into the air flow passage using the air tuyere configured as shown in FIG. 1, the emission peak intensity of a specific radical in the combustion field is measured, and the obtained light emission By comparing the peak intensity with a calibration curve prepared in advance, the combustion rate of the reducing material is estimated.

Here, the radical species for measuring the emission peak intensity may be any radical that is generated in the combustion field of the reducing material.
In the present invention, OH, CH, C ₂ , Na, K radicals and the like can be used. In particular, OH, CH, C ₂ radicals are generated during combustion even if they are not a fossil fuel reducing material. It is particularly advantageous to use these.

If such a calibration curve is obtained for each reducing material according to the present invention, the burning rate of the reducing material can be estimated by measuring the emission peak intensity of radicals in the combustion field of the reducing material used. .
According to the experiments by the inventors, depending on the type of the reducing material, there is not much difference in the relationship between the burning rate of the reducing material and the specific radical emission peak intensity in the combustion field. It was found that there was no problem even if the calibration curves were consolidated into one.

  Moreover, when the burning rate of the reducing material estimated using the above calibration curve is compared with the reducing material burning rate in the raceway 4 actually measured using the sampling device 5, a good correlation may be seen. It was confirmed.

If the burning rate of the reducing material can be accurately estimated as described above, the estimated value can be utilized for blast furnace operation to further stabilize the blast furnace operation.
If the estimated burning rate of the reducing material falls below the burning rate in the stable operation period, there is a concern that not only the amount of heat in the blast furnace will be insufficient, but also unburned char will be generated.
Therefore, in such a case, it is necessary to recover the reducing material combustion rate in the furnace.

Therefore, in the present invention, when the estimated burning rate of the reducing material is less than 0.95 relative to the burning rate in the stable operation period, the blast oxygen concentration is increased by 1 vol% or more. . In addition, it is preferable that the raise rate of ventilation oxygen concentration shall be 1-5 vol%. If it exceeds 5 vol%, the low-temperature charge reaches the lower part of the furnace due to an increase in the unloading speed of the furnace interior charge accompanying the increase of reducing gas such as CO supplied into the furnace, causing operational troubles. A more preferable increase rate of the blast oxygen concentration is 1 to 2 vol%.
Thus, as described above, an increase in the reducing material ratio accompanying a reduction in the coke replacement rate due to a reduction in the reducing material combustion rate, and a deterioration in furnace breathability due to accumulation of unburned char in the dripping zone and the furnace core Stable blast furnace operation can be performed by preventing adverse effects.
Here, the stable operation period is a period in which troubles in blast furnace operation represented by shelves, blow-throughs, tuyere blockages, tapping abnormalities, etc. have not occurred.

Further, as a countermeasure when the combustion rate of the reducing material is lowered, it has been found that the same effect can be obtained by raising the blowing temperature in addition to raising the blowing oxygen concentration.
That is, when the estimated burning rate of the reducing material is less than 0.95 relative to the burning rate during stable operation, the same problem can be dealt with by increasing the blowing temperature by 20 ° C. or more. it can. In addition, it is preferable that the raise degree of ventilation temperature shall be 20-50 degreeC. If the temperature exceeds 50 ° C., the rise in the Si concentration in the hot metal increases with the increase in the furnace heat, which is not desirable because the time and cost required for removing impurities in the subsequent process increase. A more preferable increase in the blowing temperature is 20 to 30 ° C.

(Example 1) Example of adjusting oxygen concentration during blowing Experiments were performed using a small cylindrical combustion furnace 10 having a cylindrical shape as shown in FIG. The small combustion furnace 10 has a cylindrical flow path having an inner diameter of 100 mm, and two side observations are provided at 80 mm and 280 mm apart from the tips of the reducing material blowing pipes 3-1 and 3-2 along the longitudinal direction thereof. Windows 6-1 and 6-2 are installed.

The cylindrical small combustion furnace shown in FIG. 3 was used, and hot air was blown from the upstream side under the conditions of an air flow rate of 210 Nm ³ per hour, an air temperature of 1000 ° C., and an oxygen concentration of 16, 28, 37, 43, and 49 vol%. In the hot air, pulverized coal is supplied as reducing material through two reducing material blowing pipes 3-1 and 3-2 inserted at an angle of 20 degrees from the side surface and upstream side at the position where the tip can be seen from the side observation window. Emission peak intensity of OH radicals (OH radicals: 309 nm) generated by combustion of this reducing material with 35 kg per hour, a gas simulating coke oven gas (its composition is shown in Table 1) at 22 Nm ³ per hour, fine powder relationship between the combustion rate of coal investigates (point indicated ItaBT, in ItaBO ₂ in FIG. 4), a calibration curve was prepared.

The prepared calibration curve is shown in FIG. This calibration curve was created by combining with the survey results on the relationship between the emission peak intensity of OH radicals and the combustion rate of pulverized coal obtained in Example 2 described later. Here, ηBO ₂ is a plot in the condition of this example in which the blowing oxygen concentration was changed at a constant blowing temperature (1000 ° C.), and ηBT was a plot in the condition in Example 2 in which the blowing temperature was changed at a constant blowing oxygen concentration (37 vol%). is there.
Here, the emission peak intensity was measured from the side observation window 6-1 located at a distance of 80 mm from the tip of the reducing material blowing tube. The emission peak intensity is measured using a spectroscope capable of measuring light in the wavelength range of 190 nm to 1100 nm. From the emission spectrum shown in FIG. 5 obtained by measurement using this spectroscope, the peak intensity of OH radicals is calculated. Calculated. Moreover, the burning rate of pulverized coal is obtained by collecting gas flowing in the furnace using a sampling sonde (not shown) installed on the opposite side of the side observation window 6-2 located at the tip 280 mm of the reducing material blowing pipe, Using the analytical value of the concentration of the gas in the collected gas, it was calculated using the following formula.

ここで、η_c：微粉炭燃焼率［％］，ｘ_i：１分子あたり炭素原子をi個含む気体の採取ガス中の濃度［vol％］，ｘ_N2：採取ガス中の窒素濃度［vol％］，Ｖ_N2°：送風中窒素流量［Ｎｍ^３／時］，Ｖ_i°：１分子あたり炭素原子をｉ個含む気体の送風、還元ガス中の体積の合計［Ｎｍ^３／時］，ｘ_c,pc：微粉炭中炭素原子分率［mass％］，ｍ_pc：微粉炭吹込み量［ｋｇ／時］である。

Here, η _c : pulverized coal combustion rate [%], x _i : concentration in a sampling gas of a gas containing i carbon atoms per molecule [vol%], x _N2 : nitrogen concentration in the sampling gas [vol%] ], V _N2 °: nitrogen flow rate during blowing [Nm ³ / hour], V _i °: blowing of gas containing i carbon atoms per molecule, total volume in reducing gas [Nm ³ / hour], x _{c , pc} : carbon atomic fraction [mass%] in pulverized coal, m _pc : pulverized coal injection amount [kg / hour].

FIG. 4 shows that the emission peak intensity of the OH radical has a good correlation with the pulverized coal combustion rate.
Thus, it became clear that the combustion rate of pulverized coal can be estimated by measuring the emission peak intensity of radicals using this relationship.

Next, in a test furnace simulating a blast furnace with a furnace volume of 12 m ³ , the combustion rate estimated from the measurement of the emission peak intensity of OH radicals and the stability of the blast furnace operation were verified. The amount of blown air was determined so that the amount of blast furnace discharge was constant at 30 t / day (described as t / d in Table 2 below), and the airflow resistance index was used as an indicator of operational stability. The ventilation resistance index is an index indicating the air permeability in the furnace with the pressure difference between the furnace top pressure and the air blowing pressure and the air blowing amount as parameters, and the larger this value, the worse the air permeability in the furnace. During the period of this verification, the moisture during blowing was adjusted so that the tuyere temperature was within a certain range under the condition of the blowing temperature of 1000 ° C., and the hot metal temperature was kept within the range of 1470 ° C. ± 10 ° C.
First, as a base condition, when the operation was performed under the conditions of Case 1 shown in Table 2, that is, a coke ratio of 401 kg / t, a pulverized coal ratio of 136 kg / t, and a blowing oxygen concentration of 27.0 vol%, a stable operation was performed without any trouble. I was able to. This condition was set as the stable operation period, and the pulverized coal combustion rate and the ventilation resistance index under this condition were normalized to 1.0. Next, as shown in Table 2, the airflow resistance index when operating under various conditions was relatively compared. The ventilation resistance index was a value up to 1.05, which was satisfactory for stable operation. Here, pulverized coal of the same brand was used under all conditions, and pulverized coal injection lances were used one by one for all tuyere.

Case 2 is a condition in which the pulverized coal ratio is increased by 5 kg / t with respect to Case 1. Compared to case 1, in case 2, the relative pulverized coal combustion rate decreased to 0.96 and the ventilation resistance index increased to 1.04, but it was within the range where stable operation was possible.
Case 3 is a condition in which the pulverized coal ratio is further increased from Case 2 by 5 kg / t. Compared to case 2, in case 3, the relative pulverized coal combustion rate decreased to 0.93, and the ventilation resistance index increased to 1.08. Under these conditions, the air permeability in the furnace was very poor and the coke ratio was increased to 414 kg / t, but it was very difficult to perform stable operation. As a cause of this, as described above, it is considered that unburned char accumulated in the dripping zone and the core and hindered ventilation in the furnace.
Case 4 is a case where the oxygen concentration during blowing is increased by 0.5 vol% from the conditions of case 3 and an attempt is made to improve the pulverized coal combustion rate. Compared to Case 3, in Case 4, the relative pulverized coal combustion rate rose to 0.94 and the ventilation resistance index improved to 1.06, but the coke ratio was still high at 410 kg / t, and the furnace conditions were stable. There wasn't.
Case 5 is a case where the oxygen concentration during blowing is further increased by 0.5 vol% from the condition of case 4 to attempt to improve the pulverized coal combustion rate. Compared to case 4, in case 5, the relative pulverized coal combustion rate increased to 0.95 and the ventilation resistance index was improved to 1.03. Also, the coke ratio was 395 kg / t, which was reduced by 6 kg / t compared to the base condition, Case 1. Under these conditions, unlike cases 3 and 4, stable operation was possible.
Case 6 is a condition in which the oxygen concentration during blowing is further increased by 0.8 vol% from the condition of Case 5 to attempt to improve the pulverized coal combustion rate. Compared to Case 5, in Case 6, the relative pulverized coal combustion rate increased to 0.99, stable operation was possible, and the airflow resistance index was also decreased by 0.01 compared to Case 5 to 1.02. . However, the coke ratio was 394 kg / t, and the amount of decrease compared to case 5 was only 1 kg / t.
From the above verification, it is possible to carry out stable blast furnace operation by increasing the blast oxygen concentration by at least 1 vol% so that the relative pulverized coal combustion rate with respect to the pulverized coal combustion rate during the stable operation period does not fall below 0.95. It was confirmed that.

(Example 2) Example of ventilation temperature adjustment The experiment was carried out using a cylindrical small combustion furnace 10 as shown in FIG.
The air blowing conditions were such that hot air having an air flow rate of 210 Nm ³ per hour, an air blowing temperature of 900, 1000, 1100, and 1200 ° C. and an oxygen concentration of 37 vol% was blown from the upstream side. Then, as in Example 1, through two reducing agent blowing pipe, the pulverized coal per hour 35kg as a reducing material, a gas simulating the coke oven gas per hour 22 Nm ³ blown, produced by combustion of the reducing agent The relationship between the emission peak intensity of OH radical (OH radical: 309 nm) and the combustion rate of pulverized coal was investigated.
The calibration curve obtained using this survey result is shown in FIG.
Here, the emission peak intensity was measured in the same manner as in Example 1.

  As shown in FIG. 4, it was confirmed that the emission peak intensity of OH radicals had a good correlation with the pulverized coal combustion rate. Therefore, the combustion rate of pulverized coal can be estimated by measuring the emission peak intensity of radicals using this relationship.

Next, as in Example 1, the emission peak intensity of OH radicals was measured in a test furnace simulating a blast furnace with a furnace volume of 12 m ³ , and the combustion rate estimated from the values and the stability of operation were verified. . The amount of blown air was determined so that the amount of blast furnace discharge was constant at 30 t / day (described as t / d in Table 2 below), and the airflow resistance index was used as an indicator of operational stability.
First, as the base conditions, when the operation was performed under the conditions of Case 1 shown in Table 3, that is, a coke ratio of 399 kg / t, a pulverized coal ratio of 135 kg / t, and a blowing temperature of 980 ° C., stable operation can be performed without any trouble. It was. This condition was set as the stable operation period, and the pulverized coal combustion rate and the ventilation resistance index under this condition were normalized to 1.0. Next, as shown in Table 3, the airflow resistance index when operating under various conditions was relatively compared. The ventilation resistance index was a value up to 1.05, which was satisfactory for stable operation. Here, pulverized coal of the same brand was used under all conditions, and pulverized coal injection lances were used one by one for all tuyere.

Case 2 is a condition in which the pulverized coal ratio is increased by 5 kg / t with respect to Case 1. Compared to case 1, in case 2, the relative pulverized coal combustion rate decreased to 0.97 and the ventilation resistance index increased to 1.04, but it was within the range where stable operation was possible.
Case 3 is a condition in which the pulverized coal ratio is further increased from Case 2 by 5 kg / t. Compared to case 2, in case 3, the relative pulverized coal combustion rate decreased to 0.93 and the ventilation resistance index increased to 1.07. Under these conditions, the air permeability in the furnace was very poor and the coke ratio was increased to 416 kg / t, but it was very difficult to perform stable operation. As a cause of this, as described above, it is considered that unburned char accumulated in the dripping zone and the furnace core and hindered ventilation in the furnace.
Case 4 is a case where the blowing temperature is increased by 10 ° C. from the conditions of case 3 to attempt to improve the pulverized coal combustion rate. Compared to case 3, in case 4, the relative pulverized coal combustion rate increased to 0.94 and the ventilation resistance index improved to 1.06. However, the coke ratio was still high at 409 kg / t, and the furnace condition was not stable.
Case 5 is a case where the blowing temperature is further increased by 10 ° C. from the conditions of case 4 and an attempt is made to improve the pulverized coal combustion rate. Compared to Case 4, in Case 5, the relative pulverized coal combustion rate increased to 0.95 and the ventilation resistance index improved to 1.03. Also, the coke ratio was 393 kg / t, which was 6 kg / t lower than that of case 1 which is the base condition. Under these conditions, unlike cases 3 and 4, stable operation was possible.
Case 6 is a condition in which the blowing temperature is further increased by 10 ° C. from the condition of case 5 to attempt to improve the pulverized coal combustion rate. Compared to Case 5, in Case 6, the relative pulverized coal combustion rate increased to 0.99 and stable operation was possible, but the ventilation resistance index was 1.03, which was the same value as in Case 5 . Further, the coke ratio was 392 kg / t, and the reduction width compared to Case 5 was only 1 kg / t.
From the above verification, it is possible to carry out stable blast furnace operation by raising the blast temperature by at least 20 ° C so that the relative pulverized coal combustion rate with respect to the pulverized coal combustion rate during the stable operation period does not fall below 0.95. It was confirmed that there was.

  According to the present invention, in the blast furnace operation in which the reducing material is injected, it is possible to accurately estimate the combustion rate of the reducing material in the blower tuyere and perform more stable blast furnace operation.

DESCRIPTION OF SYMBOLS 1 Blower tuyere body 2 Blow pipe part 3 Reducing material blowing pipe 4 Raceway 5 Sampling instrument 6 Observation hole 7 Observation window 8 Luminescence intensity measuring device 10 Small combustion furnace

Claims (5)

In the blast furnace operation in which the reducing material is blown into the furnace through the blowing pipe whose tip is located in the blowing channel of the blowing tuyere body or the blowing pipe part on the upstream side of the blowing tuyere,
The radical emission peak intensity in the combustion field of the reducing material is measured through an observation hole provided in the tuyere main body or the blow pipe part, and the obtained emission peak intensity is obtained from the reducing material prepared in advance. It is characterized by estimating the burning rate of the reducing material from the measured emission peak intensity of the radical in the combustion field by collating with a calibration curve representing the relationship between the combustion rate and the emission peak intensity of the radical in the combustion field. A method for estimating the combustion rate of blast furnace reducing material.   2. The reducing material according to claim 1, wherein at least one selected from pulverized coal, natural gas, propane gas, heavy oil, light oil, fossil fuel, vegetable oil, coke oven gas, and waste plastic is used as the reducing material. A method for estimating the combustion rate of blast furnace reducing material. In blast furnace operation using the method for estimating the combustion rate of the blast furnace blown reducing material according to claim 1 or 2,
A blast furnace operating method characterized by increasing the oxygen concentration in the blown air by 1 vol% or more when the estimated burning rate of the reducing material falls below 0.95 as a relative value with respect to the burning rate during stable operation. In blast furnace operation using the method for estimating the combustion rate of the blast furnace blown reducing material according to claim 1 or 2,
A blast furnace operating method characterized in that when the estimated burning rate of the reducing material falls below 0.95 as a relative value with respect to the burning rate during stable operation, the blowing temperature is increased by 20 ° C or more.   It has a blowing pipe of a reducing material whose tip is located in the air flow path of either the blower tuyere main body or the blowpipe part upstream of the blower tuyere, and either the blower tuyere main body or the blowpipe part One or both of them have an observation lance that communicates with the inside and outside thereof, and the observation lance has an observation window on the outside of the blower tuyere body or the blow pipe part, and at the other end in the blow passage. Equipped with a luminescence intensity measuring device to measure the emission peak intensity of radicals in the combustion field of the injected reducing material, and in addition, collecting the reducing material to collect the reducing material ejected from the blower tuyere into the blast furnace raceway A blower tuyere characterized by having a device.

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