JP6942641B2 - Blast furnace blown reducing agent combustion position estimation method, blast furnace operation method and blower tuyere - Google Patents

Description

The present invention relates to a method for estimating the combustion position of a blast furnace-blown reducing agent, which can accurately estimate the combustion position of the blown reducing agent in a blast furnace operation in which the reducing agent is blown into the furnace. The present invention also relates to a blast furnace operating method for achieving stable operation of the blast furnace by utilizing the above-mentioned method for estimating the combustion position of the blast furnace blown reducing agent. Furthermore, the present invention relates to a blower tuyere suitable for practicing the above-mentioned blast furnace operating method.

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

The reducing agent supplied into the blast furnace burns inside the blower tuyere and at the raceway portion formed at the tip of the blower tuyere, and can be used as a substitute for coke from the viewpoint of maintaining the heat of the lower part of the blast furnace and reducing iron oxide. Become. In order to further reduce the amount of coke used, it is necessary to increase the amount of reducing agent to be blown.
Here, since the air flow velocity in the air blower tuyere is as fast as 200 m / s, the time from when the reducing agent is blown into the air blower tuyere to reach the raw material filling layer in the furnace through the raceway is several milliseconds. Very short. Therefore, as the amount of reducing agent blown in is increased, the reducing agent that could not be completely burned in the raceway (hereinafter referred to as unburned char) invades the filling layer in the furnace and remains in the furnace. It will be.

A part of the unburned char remaining in the blast furnace is consumed in the solution loss reaction, but since the consumption is limited, a part of the unburned char that is not consumed is discharged from the furnace top and the coke replacement rate. This leads to a decrease in the ratio of reducing materials. In addition, some of the unburned char that is not consumed accumulates in the furnace core and the dropping zone, which causes deterioration of the ventilation and liquid permeability in the furnace.
For the above reasons, it is important to understand the combustion behavior of the reducing agent in order to maintain sound blast furnace operation.

One of the indexes showing the combustion behavior of the reducing agent is the combustion position of the reducing agent. There is a suitable combustion position for the reducing agent for sound blast furnace operation. That is, when the combustion position of the reducing agent approaches the blow pipe side, the atmospheric temperature inside the blow pipe and the tuyere body rises, and the risk of melting of the blow pipe and the tuyere increases. On the other hand, when the combustion position approaches the inside of the furnace, the combustion delay of the reducing agent causes an increase in unburned char, which has an adverse effect as described above on the operation of the blast furnace.

The following methods have been proposed as a method for grasping the combustion behavior including the combustion position of the reducing agent.
For example, in Patent Document 1, the temperature is calculated from the brightness of the raceway measured by the radiation temperature camera installed in the blower tuyere viewing window, and the spectral analysis of the time-series data of the temperature is performed to maximize the power density spectrum. A method has been proposed in which the raceway decay cycle is calculated from the reciprocal of the frequency and the pulverized coal combustion rate is evaluated from this decay cycle.

Further, in Patent Document 2, the light emission of the pulverized coal combustion flame is detected from the tip of the sonde installed at the tuyere of the blast furnace, and the light emission is spectroscopically analyzed. A method of observing is proposed.

Further, in Patent Document 3, the light emission of the combustion field in the raceway is imaged from the window on the back of the blast furnace blower tuyere at two different wavelengths, and the pixels of the digitized image are obtained into a histogram by obtaining the temperature from the two-color brightness. , A method of detecting the furnace condition from the shape of this histogram has been proposed.

In addition, Patent Document 4 proposes a method in which a combustion condition measuring device such as a pressure gauge, a thermometer, an area distribution measuring device, and an image measuring device is arranged near the tip of a lance, and the combustion behavior is observed from the measurement results.

In addition, in fields other than blast furnaces, the following methods have been proposed as methods for measuring the combustion behavior of fuel.
For example, in Patent Document 5, the gas combustion field is divided in the transition piece (TP) in the gas turbine, and the light emission of the gas combustion field is detected by a plurality of light receiving units provided on the inner wall of the TP and spectrally analyzed. 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.

Japanese Unexamined Patent Publication No. 7-305105 Japanese Unexamined Patent Publication No. 10-30105 Japanese Patent No. 4873788 Japanese Unexamined Patent Publication No. 2017-11259 Japanese Unexamined Patent Publication No. 2012-193978

However, the methods described in Patent Document 1 and Patent Document 3 are methods for estimating the combustion behavior of pulverized coal by measuring the brightness or the radiation temperature from the rear viewing window of the blower tuyere, and the measurement direction and the blow pipe portion. Since the gas flow in the tuyere is in 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. was there.

Further, in the methods described in Patent Documents 2 and 4, it is necessary to insert and install a sonde or a measuring device from the blow pipe to the tuyere for measuring the light emission of pulverized coal and the combustion state of the reducing material. However, when a sonde or device is inserted into the blow pipe to the tuyere, there is a problem that the gas flow in the tuyere is disturbed and the combustion behavior of the pulverized coal changes from the normal operation. Further, when the sonde is inserted into the raceway from the tuyere to measure the luminescence, there is a problem that the luminescence of pulverized coal cannot be measured correctly due to the influence of the luminescence of hot metal slag and coke.

Further, in the method described in Patent Document 5, in order to improve the controllability of the combustion temperature of the fuel, a light receiving portion such as an optical fiber is installed on the inner wall of the combustion device, and combustion is performed at a specific position in the combustion device based on the detected light. This is a method for calculating the temperature distribution of gas. However, since the liquid or solid reducing agent is also blown into the tuyere of the blast furnace, it is difficult to apply the above method in that case.

In addition, in the blow pipe section to the tuyere section, in general, a solid reducing agent may be blown as described above, and foreign substances such as brick fragments that have fallen off from the hot air furnace may enter the device together with the combustion gas. It flows. When 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 agent, and the combustion field in the furnace. In some cases, it became impossible to detect the luminescence of. Once it becomes impossible to detect light emission, it is necessary to replace the blow pipe or tuyere, but for that purpose, it is necessary to suspend the operation of the blast furnace, and there is a problem that the production amount of hot metal decreases.

The present invention advantageously solves the above-mentioned problems, and can accurately estimate the combustion position of the blown reducing agent in the operation of the blast furnace in which the reducing material is blown. The purpose is to propose a combustion position estimation method. Another object of the present invention is to propose a blast furnace operation method that realizes stable operation of the blast furnace by utilizing the above-mentioned method for estimating the combustion position of the blast furnace blown reducing agent. Furthermore, an object of the present invention is to provide a blower tuyere used for carrying out the above-mentioned blast furnace operating method.

That is, the gist structure of the present invention is as follows.
1. 1. The tip of the blower pipe is inserted into the blower flow path of the blower tuyere, which consists of the blower tuyere body and the blow pipe portion that is continuous on the upstream side of the blower tuyere body, and the reducing agent is passed through the tip portion in the blast furnace. In blowing into
Through observation holes provided in either or both of the tuyere body and the blow pipe portion, the emission intensity of the reducing agent in the combustion field is measured at at least two points in the air flow direction, and radiation is emitted from the obtained emission intensity. A method for estimating the combustion position of a blast furnace blown reducing agent, which comprises estimating the combustion position of the reducing agent by comparing the emission intensity obtained by subtracting the light intensity between the measurement points.

2. The method for estimating the combustion position of a blast furnace blown reducing material according to 1 above, wherein the object to be measured through the observation hole is a spectral spectrum, and the radiation spectrum is subtracted from the spectral spectrum.

3. 3. The combustion position of the blast furnace blown reducing material according to 1 or 2 above, wherein the object to be measured through the observation hole is the total emission intensity of the radical emission peak wavelength, and the radiant light intensity of the wavelength is subtracted from the total emission intensity. Estimating method.

4. 3. The method for estimating the combustion position of the blast furnace blown reduction material according to any one.

5. The combustion position of the reducing agent in the blower tuyere is estimated by the combustion position estimation method described in 1 to 4, and the estimated combustion position is 0 mm or more and 200 mm from the tip of the blower tuyere to the blow pipe portion side. A blast furnace operation method for adjusting the tip position of the blow pipe within the following range.

6. A blower tuyere consisting of a blower tuyere body and a blow pipe portion continuous on the upstream side of the blower tuyere body, and a blower pipe of a reducing material whose tip is located in the blower flow path of the blower tuyere. The blower tuyere body or the blow pipe portion has at least two observation holes for observing the blower flow path, and the observation holes are the blower tuyere body or the blow. A blower tuyere having an observation window on the outside of the pipe portion and a measuring device for measuring the emission intensity or the spectral spectrum of emission in the combustion field of the reducing material blown into the ventilation flow path.

7. A blower tuyere consisting of a blower tuyere body and a blow pipe portion continuous on the upstream side of the blower tuyere body, the tip portion of which is located in the blower flow path of the blower tuyere, and the tip position is in the air flow direction. It has a reducing material blowing pipe provided with a movable mechanism, and further has at least one observation hole for observing the blowing flow path in either or both of the blowing tuyere body and the blow pipe portion. The observation hole is provided with an observation window on the outside of the blower tuyere body or the blow pipe portion, and is for measuring the emission intensity or the spectral spectrum of emission in the combustion field of the reducing material blown into the blower flow path. Blower tuyere with measuring device.

According to the combustion position estimation method of the present invention, the combustion position of the reducing material can be accurately estimated by measuring the emission intensity of the combustion field in the blower tuyere, particularly the emission peak intensity of radicals. Therefore, more stable blast furnace operation can be realized by operating the blast furnace based on the estimated combustion position of the reducing agent.
Further, according to the blower tuyere of the present invention, it is possible to measure the light emission intensity of the reducing agent combustion field from outside the furnace through the observation hole, prevent damage to the light receiving part of the measuring device, and hinder the operation of the blast furnace. It contributes to the measurement to accurately grasp the combustion position of the reducing agent without causing any trouble.

It is a schematic diagram of a blower tuyere suitable for practicing the present invention. It is a schematic diagram of another example of a blower tuyere suitable for practicing the present invention. It is a schematic diagram of still another example of a blower tuyere suitable for practicing the present invention. It is a figure which shows an example of the emission spectrum of the reducing agent combustion field, and the calculation method of the emission peak intensity of radical. This is a measurement example of the relationship between the radical emission peak intensity and the distance from the tip of the lance. It is a schematic diagram which shows the cross section of a small combustion furnace. It is a figure which shows the relationship between the total light emission intensity and the distance from the tip of a lance measured in a small combustion furnace. It is a figure which shows the relationship between the radical emission peak intensity and the distance from a lance tip measured in a small combustion furnace.

Since the combustion field of the reducing agent blown into the blower tuyere body and the blower pipe section on the upstream side of the blower tuyere is in a high temperature atmosphere exceeding 2000 ° C, radicals that do not exist in the atmosphere or at room temperature are present. Generate.
As an example of the reducing material combustion field, the pulverized coal combustion field is derived from OH, CH, C ₂ radicals derived from the combustion of hydrocarbons in the pulverized coal and Na, K contained in the ash content in the pulverized coal. There are Na and K radicals.

In such a combustion field, it has been confirmed that radicals are excited by heat or a combustion reaction, and when the radicals transition from the excited state to the base state, they emit light having a wavelength peculiar to the radicals (OH radicals). : 309 nm, CH radical: 431 nm, C ₂ radical: 517 nm, Na radical: 589 nm, K radical: 766,770 nm).

Here, since the radical emission peak intensity is generated by the combustion of the reducing agent, it is considered that there is a correlation with the combustion position of the reducing agent. That is, it is presumed that at the combustion position of the reducing agent, the amount of radicals generated is larger than before and after that, and the radical emission peak intensity increases.
In the present invention, the combustion position of the reducing agent is estimated from the emission peak intensity of radicals existing in the combustion field by utilizing the above correlation.
Hereinafter, the present invention will be specifically described. First, a blower tuyere suitable for estimating the combustion position of the reducing agent from the emission peak intensity of radicals existing in the combustion field will be described with reference to FIGS. 1 to 3.

FIG. 1 shows a first form of a blower tuyere suitable for carrying out the present invention.
In the figure, reference numeral 1 is a tuyere main body, 2 is a blow pipe portion connected to the tuyere main body, 3 is a blowing pipe of a reducing agent r, and in the illustrated example, the tip of the blowing pipe 3 is a blower blade. It is inserted into the air flow path 10 of the mouth. Reference numeral 4 is a raceway of the blast furnace, 5-1 and 5-2 are observation holes leading to the inside and outside of the blow pipe portion 2, and 6-1 and 6-2 are observation holes 5-1 and 5-2, respectively. The observation windows 7-1 and 7-2 provided on the outside of the pipe portion are light emission intensity measuring devices for measuring the light emission intensity in the air flow path 10 from the outside of the observation windows 6-1 and 6-2.

The position and insertion angle of the tip of the blow pipe 3 are not limited to the illustrated examples, and the blow pipe 3 can be installed by appropriately changing it. For example, there is no problem even if the tip of the blow pipe 3 is installed at the position and angle of the blower tuyere main body 1 of the blower flow path 10.

Further, the observation hole is not limited to the installation position in the illustrated example, but the position in the hot air blowing direction (hereinafter referred to as the blowing flow direction) can be specified, and the light emission of the reducing agent combustion field in the furnace can be measured. For example, the installation location does not matter. The number of observation holes is not limited to two, but may be three or more. However, when the insertion position of the blow pipe 3 shown in FIG. 1 is fixed, at least two observation holes need to be installed. This also applies to the observation window and the emission intensity measuring device attached to the observation hole, and at least two of each are required.

Further, the emission intensity measuring device 7 may be of any type as long as it is a spectroscopic device that satisfies the condition that the emission peak intensity of radicals can be calculated. The method for calculating the emission peak intensity of radicals will be described later.

Next, FIG. 2 shows a second form of a blower tuyere suitable for carrying out the present invention. This blower tuyere has the same configuration as the blower tuyere of FIG. 1 except that the blower pipe 3 in the blower tuyere of FIG. be. That is, the blow pipe 3 is provided with a moving mechanism 8 for moving the tip position thereof, and the tip position can be changed in the air flow direction. The type of the moving mechanism 8 is not particularly limited as long as the tip position of the blowing pipe 3 can be changed in the blowing flow direction. As the moving mechanism 8, for example, a mechanism in which the rod of the hydraulic cylinder is connected to the blow pipe 3 and the blow pipe 3 is slid in the axial direction thereof can be applied.

Further, the third form of the blower tuyere shown in FIG. 3 is similar to the form of FIG. 2 described above, in which the blow pipe 3 in the blower tuyere is movable and the observation hole is unified. That is, the blow pipe 3 is provided with a moving mechanism 9 for moving the tip position thereof, and the tip position can be changed in the air flow direction. In this moving mechanism 9, a pedestal 90 that fixedly supports the blow pipe 3 is slidably attached to a slot 20 provided in the blow pipe portion 2, and the tip position of the blow pipe 3 is changed by moving the pedestal 90. be able to.

Next, a method of estimating the combustion position of the reducing agent will be described in detail.
FIG. 4 shows an example of the spectral spectrum of light emission measured in the reducing agent combustion field.

In the spectroscopic spectrum, the total emission intensity at each wavelength is measured as the sum of radiant light from refractories and reducing materials in the furnace and chemiluminescence caused by radicals, that is, radical emission. Of these, the radiant light intensity mainly depends on the temperature and radiation rate of the object that emits radiant light, the radiation rate differs depending on the substance, and the radiation rate of unburned char is generally high, so the radiation rate increases due to the progress of combustion. In addition to the fact that it may decrease, radiant light other than the reducing material such as fireproof material in the furnace inevitably enters the detection end during spectroscopic measurement, so that the radiant light causes erroneous detection of the combustion position. On the other hand, the radical emission intensity generally increases due to an increase in the amount of radicals generated due to combustion. Therefore, the total emission intensity, which is the sum of the radiation intensity and the radical emission intensity, may reduce the estimation accuracy of the combustion position. Therefore, it is necessary to eliminate the influence of radiated light in the calculation of the radical emission peak.

Here, in order to eliminate the influence of radiated light, attention was paid to the fact that the peak of the spectrum of radiated light was broader (not sharp) than that of radical emission, and it appeared in the spectral spectrum as shown in FIG. A method of obtaining the radical emission peak intensity can be used by connecting the portions other than the wavelength of the radical emission with a straight line (dotted line in FIG. 4) and subtracting the radiated light region approximated by this straight line from the total emission intensity. This method can be applied to the radical emission peaks of any substance in the combustion field of the reducing agent described above.

The above method is simple as a method for eliminating the influence of radiant light, but in addition, a method of estimating the spectrum of radiant light using an appropriate function or peak fitting using an appropriate function is performed. A method of estimating the radical emission peak intensity can also be applied. As the function, for example, a Gaussian function, a Lorentz function, or a Voigt function can be used.

FIG. 5 shows the results of measuring and calculating the radical emission peak intensity in the combustion field by changing the distance from the tip of the blow pipe using the method shown in FIG. 4 described above. Here, the radical emission peak intensity was obtained from the spectral spectrum measured by changing the position of the tip of the lance by a slide mechanism using the blower tuyere shown in FIG. 2 according to the procedure shown in FIG.

That is, as shown in FIG. 5, the relationship between the radical emission peak intensity in the combustion field of the reducing agent and the radical emission peak measurement position from the tip of the reducing agent blowing tube is shown, and the position where the radical emission peak intensity has the maximum value is It exists and is presumed to be the position closest to the combustion position.

As described above, when the blast furnace is operated by blowing the reducing agent into the air flow path using the air tuyere having the configuration shown in any one of FIGS. 1, 2 or 3, the emission peak intensity of a specific radical in the combustion field is used. The combustion position of the reducing agent can be estimated from the relationship between the obtained radical emission peak intensity and the radical emission peak intensity measurement position from the tip of the blowing tube.

Here, the radical species for which the emission peak intensity is measured may be any radical as long as it is a radical generated in the combustion field of the reducing agent. In the present invention, OH, CH, C ₂ , Na, K radicals and the like can be used, but in particular, OH, CH, C ₂ radicals are always generated during combustion if they are hydrocarbon-based reducing materials. , It is advantageous to use these.

If the combustion position of the reducing agent can be accurately estimated as described above, the blast furnace operation can be further stabilized by utilizing this estimated value for the blast furnace operation. That is, if the estimated combustion position of the reducing agent deviates significantly from the combustion position in the stable operating period before the change of the operating conditions due to the change of the operating conditions such as the increase / decrease of the ratio of the reducing agent blown from the tuyere. There is concern that unburned char will be generated due to the delay in combustion of the reducing agent, or that the tuyere heat load will increase. Therefore, in such a case, it is necessary to correct the combustion position of the reducing agent in the furnace, the tuyere, and the blow pipe.

Therefore, in the present invention, the tip position of the blow pipe is adjusted so that the estimated combustion position of the reducing agent is in the range of 0 mm or more and 200 mm or less from the tip of the blower tuyere to the blow pipe portion side. do. This is because when the combustion position of the reducing agent moves from the tip of the blower tuyere to the inside of the furnace, the amount of the unburned reducing agent reaching the inside of the furnace increases and the unburned reducing agent accumulates in the furnace, resulting in poor air permeability. However, adverse effects on operations such as an increase in the ratio of reducing agents become significant. Similarly, if the combustion position of the reducing agent moves from the tip of the blower tuyere to the blow pipe portion side by more than 200 mm, the reducing agent burns excessively in the blow pipe or the blower tuyere, and the heat load at the tuyere increases. However, in the worst case, it will lead to melting of the tuyere. Therefore, it is important to adjust the tip position of the blow pipe and set the combustion position of the reducing agent estimated thereafter in the range of 0 mm or more and 200 mm or less from the tip of the blower tuyere to the blow pipe portion side.
The position of the reducing agent combustion after adjusting the tip position of the blow pipe is preferably 100 mm or more and 200 mm or less from the tip of the blower tuyere to the blow pipe portion side as much as possible. This is because if there is no problem with the tuyere heat load, the reducing agent ratio can be reduced by pulling the blow pipe toward the blow pipe portion as much as possible and promoting the combustion of the pulverized coal.

The method of estimating the combustion position of the reducing agent was verified using the small cylindrical combustion furnace 11 shown in FIG. This small combustion furnace 11 has a columnar flow path having an inner diameter of 100 mm, and a total of three side observation windows 11-1, 11-2, and 11-3 are installed at intervals of 200 mm along the longitudinal direction thereof. There is.
Using the small cylindrical combustion furnace shown in FIG. 6 ^{, hot air was blown from the upstream side under the conditions of an air flow rate of 270 Nm 3 /} h, an air flow temperature of 1250 ° C., and an oxygen concentration of 27 vol%. 35 kg of pulverized coal as a reducing material is blown into the hot air through one blowing pipe 12 inserted at an angle of 20 degrees with respect to the blowing flow direction from the side surface / upstream side, and by combustion of this reducing material. The relationship between the emission peak intensity of the generated OH radical (OH radical: 309 nm) and the distance from the tip of the blow tube to the measurement position was investigated.

The distance from the tip of the blow pipe to the measurement position was changed by changing the insertion depth of the blow pipe. That is, the position where the tip of the blow pipe can be seen from the uppermost flow end of the side observation window 11-1 is set to the position of 0 mm, and the blow is blown so that the tip of the blow pipe is 40 mm, 80 mm, and 120 mm behind in the air flow direction from that position. The measurement was performed with a shallow tube insertion depth. The change was made, and the spectral spectra of the light emission of the reducing agent combustion field were measured at a total of 12 locations 30 mm to 550 mm from the tip of the blow tube.

With respect to the obtained spectral spectrum, a scatter diagram in which the measurement result of the total emission intensity is plotted against the distance from the tip of the blow tube to the measurement position is shown in FIG. FIG. 8 shows a dispersion diagram in which the radical emission peak intensity at the emission wavelength (309 nm) of the OH radical after subtracting the intensity is plotted against the distance from the tip of the blowing tube to the measurement position. As shown in FIG. 8, when focusing on the radical emission peak intensity, it can be seen that the distance has the maximum value at the position of 270 mm and the combustion position is the position of 270 mm from the tip of the blow pipe.

On the other hand, focusing on the total emission intensity, which is the sum of the radiation intensity and the radical emission intensity, as shown in FIG. 7, although the maximum value is 270 mm, it has a maximum value close to the intensity at the position of 510 mm. For example, when two measurements are performed in a region of 200 to 600 mm from the tip of the blow pipe in FIG. 6, it is highly possible that the estimated combustion position differs depending on the measurement position. Focusing on the radical emission peak intensity, although it has a maximum value at the position of 510 mm, the intensity is not much different from the surrounding positions of 470 mm and 550 mm, and the influence on the estimation accuracy of the combustion position is much smaller. In this way, the combustion position of the pulverized coal could be accurately estimated based on the radical emission peak intensity.

Next, in a test furnace simulating a blast furnace with an internal volume of 12 m ³ , the emission peak intensity of OH radicals was calculated from the spectroscopic measurement results, and the combustion position and operational stability estimated from those values were verified. The amount of air blown to the blast furnace was determined to be constant at 30 t / day (described as t / d in Table 2 below), and the aeration resistance index was used as an index 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 ventilation pressure and the ventilation amount as parameters, and can be specifically obtained according to the following formula. The larger this value is, the worse the air permeability in the furnace is. During this verification period, the operation was performed under the conditions of a blast temperature of 1000 ° C. and a blast oxygen enrichment of 6%, that is, a blast oxygen concentration of 27%, and the hot metal temperature was kept within the range of 1470 ° C. ± 10 ° C.
Record
(Ventilation resistance index) = (PB ² -PT ² ) / VB ^1.7
Here, PB: Blast pressure [g / cm ² ]
PT: Furnace top pressure [g / cm ² ]
VB: Air volume [Nm ³ / min]

First, as the base conditions, the operation was carried out under the conditions of Case 1 shown in Table 1, that is, the coke ratio of 401 kg / t and the pulverized coal ratio of 136 kg / t (reducing agent ratio of 537 kg / t). Under this condition, the luminescence of the pulverized coal combustion field was measured at the blower tuyere of FIG. When the charcoal combustion position was estimated, the combustion position of the pulverized coal was -100 mm (100 mm toward the blow pipe portion side) from the tip of the blower tuyere.

Here, the unit of kg / t represents the weight of pulverized coal required to produce 1 ton of hot metal unless otherwise specified. The position of the blower tuyere from the tip was defined as 0 mm at the tip, positive as the inside of the furnace, and negative as the blow pipe side. Under these conditions, stable operation was possible without any trouble. Hereinafter, the ventilation resistance index under this condition is set to 1.00, and the ventilation resistance is described using the relative ventilation resistance index.

Then, as shown in Tables 1 and 2, the conditions (pulverized coal ratio) were variously changed to perform the operation, and the combustion position from the tip of the blower tuyere was measured. The combustion position was estimated from the transition of the OH radical peak intensity with respect to the distance from the blow pipe by measuring the luminescence of the pulverized coal combustion field at the blower tuyere of FIG. 2 to obtain the luminescence peak intensity of OH radicals. ..

Then, the relative ventilation resistance index was used to evaluate the air permeability in the furnace, and the tuyere temperature was used to evaluate the tuyere heat load. The relative aeration resistance index was a value up to 1.05 that was not a problem for stable operation. The tuyere was controlled with a heat resistant temperature of 200 ° C. Here, the pulverized coal used the same brand under all conditions, and the pulverized coal blowing lance used one single tube at all tuyere.

Case 2 is a condition in which the pulverized coal ratio is increased by 3 kg / t with respect to Case 1. In case 2, the combustion position was -50 mm. The relative aeration resistance index increased to 1.02 due to the delay in pulverized coal combustion due to the combustion position approaching the inside of the furnace, 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 by 1 kg / t from Case 2. In case 3, the combustion position was 0 mm, and the relative aeration resistance index increased to 1.04. The aeration resistance index increased due to the delay in pulverized coal combustion due to the combustion position being closer to the inside of the furnace than Case 2, but it was within the range where stable operation was possible.

Case 4 is a condition in which the pulverized coal ratio is further increased by 1 kg / t from Case 3. In case 4, the combustion position was 50 mm, and the relative aeration resistance index increased to 1.06. Under this condition, the air permeability in the furnace was very poor, and although the coke ratio was increased to 412 kg / t (reducing agent ratio of 553 kg / t), stable operation became very difficult. The reason for this is that the combustibility of pulverized coal deteriorated due to the increase in the pulverized coal ratio and the number of unburned chars increased, and the increased unburned chars accumulated in the dropping zone and the furnace core, obstructing the ventilation inside the furnace. Can be considered.

In the case 5, the combustion position is set to -100 mm, which is the same as in the case 1, by moving the tip position of the reducing agent blowing pipe to the blow pipe side by 150 mm from the condition of the case 4, and the condition is to try to guarantee the pulverized coal combustibility. be. In Case 5, the relative aeration resistance index improved to 1.01, and the coke ratio was 396 kg / t (537 kg / t as a reducing agent ratio), which was 5 kg / t lower than that of Case 1. Under this condition, unlike Case 4, stable operation was possible.

The case 6 is a condition in which the combustion position is set to −200 mm by moving the tip position of the reducing agent blowing pipe to the blow pipe side by 100 mm from the condition of the case 5. In Case 6, the operation could be maintained under the conditions of the relative aeration resistance index of 1.00 and the coke ratio of 394 kg / t (reducing agent ratio of 535 kg / t). Under this condition, although the tuyere temperature rose, the temperature was below the control value, and stable operation could be performed as in Case 5.

Case 7 is a condition in which the combustion position is set to −250 mm by moving the tip position of the reducing agent blowing pipe to the blow pipe side by 50 mm from the condition of case 6. In Case 7, the relative aeration resistance index was 0.99 and the coke ratio was 393 kg / t, but the tuyere temperature exceeded the control value of 200 ° C. and reached 204 ° C. Under this condition, the heat load on the tuyere was large, and the safety was lacking in consideration of the long-term durability of the tuyere. The cause of the increase in the tuyere heat load is that the combustion position of the pulverized coal moved to the upstream side of the tuyere due to the blow pipe moving closer to the blow pipe side, and the pulverized coal flew near the tuyere at a higher temperature. Can be considered. Therefore, when the position of the tip of the blow pipe was returned to the condition of Case 5, stable operation could be performed.

Case 8 is a condition in which the pulverized coal ratio is reduced by 3 kg / t from the condition of Case 1. Under this condition, the combustion position was -150 mm and the tuyere temperature rose to 179 ° C, but the upper limit of 200 ° C was not reached and the operation could be performed safely.

Case 9 is a condition in which the pulverized coal ratio is further reduced by 2 kg / t from Case 8. Under this condition, the combustion position was -200 mm and the tuyere temperature rose to 195 ° C, but the upper limit of 200 ° C was not reached and the operation could be performed safely.

Case 10 is a condition in which the pulverized coal ratio is further reduced by 1 kg / t from Case 9. Under this condition, the combustion position was -250 mm. The tuyere temperature rose to 203 ° C and exceeded the control value of 200 ° C. Under this condition, the heat load on the tuyere was large, and the safety was lacking in consideration of the long-term durability of the tuyere. It is considered that the cause of the increase in the tuyere heat load is that the combustibility of the pulverized coal is improved due to the decrease in the pulverized coal ratio, the combustion position is moved away from the inside of the furnace, and the particle temperature of the pulverized coal in the vicinity of the tuyere is increased.

Case 11 is a condition in which the combustion position is set to -100 mm, which is the same as that of case 1, by moving the tip position of the reducing agent blowing pipe to the inside of the furnace by 150 mm from the condition of case 10, and an attempt is made to reduce the tuyere heat load. .. Under this condition, the tuyere temperature dropped to 170 ° C., and unlike Case 10, the operation could be performed in a safe tuyere temperature range.

The case 12 is a condition in which the combustion position is set to 0 mm by further moving the tip position of the reducing agent blowing pipe 100 mm inward from the condition of the case 11. Under this condition, although the relative aeration resistance index increased due to the delay in pulverized coal combustion due to the movement of the blow pipe to the inside of the furnace, the tuyere temperature was 165 ° C, and the operation could be performed within a safe tuyere temperature range. did it.

The case 13 is a condition in which the combustion position is set to 50 mm by further moving the tip position of the reducing agent blowing pipe to the inside of the furnace by 50 mm from the condition of the case 12. Under this condition, the tuyere temperature dropped to 161 ° C., but the relative aeration resistance index became 1.07, which exceeded 1.05, and the coke ratio was increased to 422 kg / t (552 kg / t as the reducing agent ratio). However, it became very difficult to carry out stable operation. It is considered that the cause of this is that the combustion of pulverized coal was delayed due to the movement of the combustion position and the number of unburned chars increased, and the increased unburned chars accumulated in the dropping zone and the core, which hindered the ventilation in the furnace. ..

From the above verification, the blast furnace can be operated stably and safely by adjusting the position of the tip of the reducing agent blowing pipe so that the combustion position is 0 mm or more and 200 mm or less on the blow pipe side from the tip position of the blower tuyere. It was confirmed that it could be done.

According to the present invention, in the blast furnace operation in which the reducing agent is blown, the combustion position of the reducing agent in the blower tuyere can be accurately estimated, and the estimation result can be used to stably and safely carry out the blast furnace operation. became.

1 Blower tuyere body 2 Blow pipe 3 Blow pipe 4 Raceway 5 Observation hole 6 Observation window 7 Emission intensity measuring device 10 Blower flow path 11 Small combustion furnace 11-1 to 3 Small combustion furnace observation window 12 Small combustion furnace Blowing pipe

Claims (5)

The tip of the blower pipe is inserted into the blower flow path of the blower tuyere, which consists of the blower tuyere body and the blow pipe portion that is continuous on the upstream side of the blower tuyere body, and the reducing agent is passed through the tip portion in the blast furnace. In blowing into
Through the observation holes provided in either or both of the tuyere body and the blow pipe portion, the spectral spectra of the light emission of the reducing material in the combustion field were measured at at least two points in the air flow direction, and the obtained spectral spectra were obtained. It is characterized in that the combustion position of the reducing material is estimated by comparing the radical emission peak intensity after the treatment of subtracting the radiant light intensity by subtracting the portion other than the wavelength of the radical emission appearing in the above measurement points. A method for estimating the combustion position of the blast furnace blown reduction material. The blast furnace blow-down reduction 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. Method of estimating the combustion position of the material. The combustion position of the reducing agent in the blower tuyere is estimated by the combustion position estimation method according to claim 1 or 2 , and the estimated combustion position is 0 mm or more from the tip of the blower tuyere to the blow pipe portion side. A blast furnace operating method for adjusting the tip position of the blow pipe within a range of 200 mm or less. A blower tuyere consisting of a blower tuyere body and a blow pipe portion continuous on the upstream side of the blower tuyere body, and a blower pipe of a reducing material whose tip is located in the blower flow path of the blower tuyere. The blower tuyere body or the blow pipe portion has at least two observation holes for observing the blower flow path, and the observation holes are the blower tuyere body or the blow. A blower tuyere having an observation window on the outside of the pipe portion and a measuring device capable of calculating the emission peak intensity of radicals in the combustion field of the reducing material blown into the blower flow path. A blower tuyere consisting of a blower tuyere body and a blow pipe portion continuous on the upstream side of the blower tuyere body, the tip portion of which is located in the blower flow path of the blower tuyere, and the tip position is in the air flow direction. It has a reducing material blowing pipe provided with a movable mechanism, and further has at least one observation hole for observing the blowing flow path in either or both of the blowing tuyere body and the blow pipe portion. The observation hole is provided with an observation window on the outside of the blower tuyere body or the blow pipe portion, and is a measuring device capable of calculating the emission peak intensity of radicals in the combustion field of the reducing material blown into the blower flow path. Blower tuyere to have.

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