JP2010222656A - Method for measuring thickness of stuck-material layer of stave in blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for quantitatively and precisely enabling to measure the thickness of stuck material layer at a low cost even during operating a blast furnace. <P>SOLUTION: A stave-casting thermometer 4 having a measuring part 40 in the stave-casting 3, and a thermal-sensor 5 which has a plurality of measuring parts 51,52,53 in the thickness direction of the stave-casting 3 and projects at least one of the measuring part 51 among the plurality of measuring parts into the blast furnace and sets by penetrating the stave-casting 3 so as to position the other at least one of measuring part 53 into the stave-casting 3, are provided. A heat-conductivity λa of the stuck material layer 6 is calculated and also, the thickness L of the stuck material layer is calculated by using the measured temperature data with the stave thermometer 4 and the thermal-sensor 5 and simultaneously solving a plurality of heat-conductive equations containing the heat-conductivity λa and the thickness L of the stuck material layer as unknown quantities, in the respective setting position of the stave thermometer 4 and the thermal-sensor 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for measuring the thickness of a deposit layer attached to a blast furnace stave.

  When the furnace wall of the blast furnace is newly installed, a cast iron cast stave is installed inside the iron skin, and a refractory brick layer is further provided inside the stave. However, in a blast furnace after a certain number of years of operation, the refractory brick layer is worn or dropped and completely disappears, and an adhering layer is directly formed on the surface of the stave casting.

  In recent years, there have also been installation examples in which a stadium made of copper or copper alloy is used instead of cast iron and the refractory layer on the inside is omitted from the beginning. It is the same that the kimono layer is formed.

  The deposit layer grows to a certain thickness and serves as self-flying to protect the stave body from thermal shock and wear. However, the deposit layer is formed by condensing zinc and alkalis on the surface of the stave and involving slag, ore powder, etc., but if the deposit layer grows rapidly due to gas flow stagnation in the vicinity of the stave surface, etc. In addition to lowering the charge in the blast furnace and uneven gas flow, not only lowering the productivity of the blast furnace, but if large deposits fall off, the tuyere breaks down and the sudden blast furnace that accompanies it The risk of wind breaks increases.

  Therefore, it is required to always monitor the formation state of the deposit layer on the surface of the stave and take immediate action when detecting the tendency of the deposit layer thickness to increase. For this reason, there has been a strong demand for the development of a method capable of measuring the deposit layer thickness quantitatively and accurately even during operation of the blast furnace.

  As such a deposit layer thickness measurement technique, Patent Document 1 has a plurality of temperature measurement parts in the refractory thickness direction of the blast furnace wall, at least one of which protrudes into the blast furnace, and each temperature measurement value Refractories and deposits by analyzing the relationship between the time lag between each temperature measurement part and the distance between each measurement part when the periodical fluctuations corresponding to the raw material charging period A technique for obtaining the boundary position and the innermost surface position of the deposit has been proposed.

  Further, Patent Document 2 has a plurality of temperature measuring units in the refractory thickness direction of the blast furnace wall, and is arranged so that at least one of them protrudes into the blast furnace and at least one is located in the refractory. Then, frequency analysis is performed on the time-series data of each temperature measurement value, and for the analysis result, the fluctuation intensity of the frequency component above the predetermined value is extracted, and based on the fluctuation intensity of the temperature measurement part located in the refractory, There has been proposed a technique for determining whether or not the temperature measurement unit is in the deposit.

  Further, in Patent Document 3, in a measuring apparatus for measuring the thickness of deposits attached to the blast furnace wall, a vertical tip in which one end of a cylindrical body made of a heat-resistant and wear-resistant material is obliquely crossed with the axis of the cylindrical body. Cut a plane into a slant-cut straight cylinder, drill a plurality of pores parallel to the axis of the slant-cut straight cylinder from the other side of the slant-cut cylinder, and put a thermometer on the pore By using the inserted measuring device, it is possible to constantly monitor the growth of deposits grown on the surface of the stave cooler even at the place where the copper and copper alloy stave cooler is used. There has been proposed a technique for quickly estimating the fluctuations of the above.

  However, the techniques described in Patent Documents 1 and 2 have the temperature fluctuation characteristics in the furnace, the deposit, and the refractory by positioning at least one temperature measuring unit in the refractory constituting the furnace wall. Since the deposit thickness is measured (estimated) using the difference, it cannot be used for the furnace wall composed of stave.

  In addition, the technique described in Patent Document 3 is configured with an expensive heat-resistant and wear-resistant material and has a structure in which a tip portion thereof is cut obliquely and is protruded and installed in the furnace. In addition to an increase in the cost of the measuring device, it is assumed that the sharp end portion of the measuring device is easily damaged, and the life of the measuring device is extremely shortened.

Japanese Patent Publication No. 61-6125 JP-A-8-81707 Japanese Patent No. 3910347

  Therefore, an object of the present invention is to provide a method that can measure the thickness of the deposit layer quantitatively and accurately even during operation of a blast furnace at low cost.

  The invention according to claim 1 is a method for measuring the thickness of a deposit layer adhering to the surface of a blast furnace stave casting, the stave casting thermometer having a measuring portion in the stave casting, and the stave casting It has a plurality of measurement parts in the thickness direction, and at least one measurement part of the plurality of measurement parts protrudes into the blast furnace, and at least one measurement part of the plurality of measurement parts is in the stave casting. A temperature sensor installed through the stave casting so as to be positioned, and using the temperature data measured by the stave thermometer and the temperature sensor, each installation of the stave thermometer and the temperature sensor The thermal conductivity of the deposit layer is calculated simultaneously by solving a plurality of heat transfer equations including unknown values of the thermal conductivity and thickness of the deposit layer at the location. Is a measurement method of the blast furnace stave deposit layer thickness and calculates the thickness of the object layer.

  According to a second aspect of the present invention, in the measurement method according to the first aspect, after the measurement part protruding into the blast furnace of the temperature sensor is damaged, the measurement part protruding into the blast furnace is damaged. Using the thermal conductivity of the deposit layer previously calculated by the method of claim 1 as a known number, using the temperature data measured by the stave thermometer and the temperature sensor, a stave casting thermometer and the A blast furnace stave deposit that calculates the thickness of the deposit layer by simultaneously solving a plurality of heat transfer equations including only the thickness of the deposit layer as an unknown at each location where the temperature sensor is installed It is a measuring method of layer thickness.

  According to the first aspect of the present invention, temperature data measured using a stave casting thermometer and a temperature sensor having a plurality of measuring portions, at least one of which is protruded into the blast furnace, is used. By simultaneously solving a plurality of heat transfer equations including the thermal conductivity and thickness of the deposit layer as unknowns, calculating the thermal conductivity of the deposit layer and calculating the thickness of the deposit layer, With a simple device configuration, the deposit layer thickness can be estimated (measured) at low cost and with high accuracy.

  In addition, according to the invention described in claim 2, after the measurement part protruding into the furnace is damaged, the calculation according to claim 1 is performed before the measurement part protruding into the furnace is damaged. In the blast furnace, the thickness of the deposit layer is calculated by simultaneously solving a plurality of heat transfer equations including only the thickness of the deposit layer as an unknown, using the thermal conductivity of the deposited layer as a known number. Even after the measurement part protruding to the surface is broken, the estimation (measurement) of the deposit layer thickness can be continued, and long-term measurement is possible.

It is a horizontal sectional view showing a schematic structure of a blast furnace stave deposit layer thickness measuring device concerning one embodiment of the present invention. It is a graph which shows the relationship between the distance between two measurement parts in a temperature sensor, and the temperature gradient between two measurement parts. It is a radar chart figure which shows the relationship between the estimated value Lc of the deposit | attachment layer thickness, and the measured value Lm. It is a transition graph figure which shows each time-dependent change of stave casting temperature Ts, temperature sensor most recent side temperature T1, and the estimated value Lc of a deposit layer thickness after application of this invention. It is a graph which shows the relationship between the through-flow heat flux Q and the deposit layer thickness Lc.

(Embodiment)
[Configuration of measuring device]
FIG. 1 shows a schematic configuration of a blast furnace stave deposit layer thickness measuring apparatus according to an embodiment of the present invention.

  In the figure, 1 is an iron skin, 2 is a heat insulating material, 3 is a stave casting (also simply referred to as “stave”), 4 is a stave casting thermometer, 5 is a temperature sensor, and 6 is a deposit layer.

  The stave casting thermometer 4 is a shaft-like body and has a thermocouple built in the tip 40 thereof. The stave casting is such that the tip position 40 is located outside the furnace by a predetermined distance (d0) from the surface of the stave casting 3. 3 is inserted.

  The stave casting thermometer 4 is a measurement in a relatively low temperature region in a water-cooled stave casting, and therefore, for example, a grounded sheath thermocouple having excellent thermal response may be used.

  On the other hand, the temperature sensor 5 is a shaft-like body and has a plurality of (three points in this example) measuring units (51, 52, 53 in this example) in the longitudinal direction of the temperature sensor 5, The measuring part 51 on the most advanced side is protruded into the blast furnace, and the measuring part 53 on the rearmost side is installed through the stave casting 3 so as to be located in the stave casting 3.

  As will be described later, the tip position 50 of the temperature sensor 5 and the measuring portion 51 on the foremost side are positioned inside the normal deposit layer thickness, and the middle measuring portion 52 is positioned on the surface of the stave casting 3. Is recommended.

  As the temperature sensor 5, for example, a stainless steel protective tube with a non-grounded sheath thermocouple with low noise in a high temperature region incorporated through MgO powder as a filler is recommended.

  The measuring unit 51 of the temperature sensor 5 is preferably as close as possible to the tip position 50 of the temperature sensor 5 in order to increase the estimation accuracy of the temperature T0 at the tip position 50 of the temperature sensor 5, but the non-grounding type sheath When a thermocouple is built in, a certain distance is required because an insulating portion is essential at the distal end of the sheath. Therefore, it is preferable that the distance d0 from the tip position 50 of the temperature sensor 5 to the measurement unit 51 on the most advanced side is within 10 mm, more preferably within 5 mm.

  Further, if the distances d1 and d2 between the measurement parts of the temperature sensor 5 are too close, the temperature difference is too small, while if too far, the influence of heat transfer from the side surface of the temperature sensor 5 becomes large. Since the gradient appears to be small, it is preferably in the range of 10 to 30 mm (see Examples and FIG. 2 described later).

  Of course, both the stave casting thermometer 4 and the temperature sensor 5 are installed avoiding a cooling pipe (not shown) disposed in the stave casting 3.

[Attachment layer thickness estimation logic]
Next, an example of logic for estimating (measuring) the thickness of the deposit layer 6 using temperature data measured by the stave casting thermometer 4 and the temperature sensor 5 will be described with reference to FIG.

  In FIG. 1, Ts is the temperature of the tip 41 of the stave casting thermometer 4, T1, T2, and T3 are the temperatures of the measuring parts 51, 52, and 53 of the temperature sensor 5, Tm is the temperature of the surface of the deposit layer 6, and Tw is Temperature of stave casting 3 surface, T0 is temperature of tip of temperature sensor 5, λs is thermal conductivity of stave casting 3, λa is thermal conductivity of deposit layer 6, λf is thermal conductivity of temperature sensor 5, and d0 is stave The distance between the tip 41 position of the casting thermometer 4 and the surface of the stave casting 3, d1 is the distance between the tip position of the temperature sensor 5 and the measurement unit 51, d2 is the distance between the measurement unit 51 and the measurement unit 52 of the temperature sensor 5, d3 is the distance between the measuring part 52 and the measuring part 53 of the temperature sensor 5, L is the thickness of the deposit layer 6, and Q is the through-flow heat flux of the furnace wall (heat flow per unit area passing through the furnace wall). .

  Here, Ts, T1, T2, T3, λs, λf, d0, d1, d2, and d3 are known numbers, and Tm, Tw, T0, λa, L, and Q are unknown numbers.

  Hereinafter, a procedure for obtaining the unknowns Tm, Tw, T0, λa, L, and Q will be described.

  First, the once-through heat flux Q of the furnace wall is obtained by the following equation (1) from the temperature gradient between the two measurement parts 51 and 52 of the temperature sensor 5.

    Q = λf (T2-T3) / d3 (1)

  Next, the temperature Tw of the surface of the stave casting 3 is expressed by the following formula (2) from the above-mentioned once-through heat flux Q and the temperature Ts of the tip 40 of the stave casting thermometer 4 (hereinafter sometimes referred to as “stave casting temperature”). Desired.

    Tw = Ts + d0 × Q / λs (2)

  Next, the temperature T0 at the tip position 50 of the temperature sensor 5 is obtained by the following equation (3) from the through-flow heat flux Q and the temperature T1 of the measurement unit 51.

    T0 = T1 + Q / λf (3)

  Next, the thermal conductivity λa of the deposit layer 6 is obtained by the following formula (4) from the temperature T0 at the tip of the temperature sensor 5 and the temperature Tw on the surface of the stave casting 3.

    λa = (d1 + d2) × Q / (T0−Tw) (4)

  The temperature Tm on the surface of the adhering material layer 6 and the thickness L of the adhering material layer 6 remain as unknown numbers. However, the relationship of the following formula (5) is established between Tm and L, and Tm is a known number. Then, L is obtained by the same equation.

      L = λa (Tm−Tw) / Q (5)

  Here, the temperature Tm on the surface of the deposit layer 6 is considered to correspond to the melting temperature of the deposit layer 6. Therefore, when the temperature T1 on the most front side of the temperature sensor 5 rises rapidly, it can be estimated that the deposit layer 6 is melted to the tip position 50 of the temperature sensor 5 and the tip position 50 is exposed. Therefore, since L at that time is equal to d2 (L = d2), the values of Q, Tw, and λa at that time are obtained from the above equations (1), (2), and (4), and these values and L = Tm is obtained by substituting d2 into the above equation (5).

  Thereafter, L can be obtained by the above equation (5) using Tm thus obtained.

  In the above logic, the heat transfer in the direction along the furnace wall is ignored, but in actuality, there is an influence of the heat transfer in the direction along the furnace wall. Contains a certain error.

  Therefore, as usual, during the blast furnace break, a through-hole is drilled in the deposit layer 6 through a through-hole provided in the stave casting 3 in advance (sealing during operation), and the stave A metal rod having a bowl-shaped tip is inserted into the through hole of the casting 3 and the deposit layer 6 to measure the thickness Lm of the deposit layer 6. Then, the correction coefficient α = Lm / L is obtained from the actual measurement value Lm and the estimated value L of the deposit layer 6 thickness obtained by the above equation (5) immediately before the break. Then, by calculating Lc (= α × L) obtained by multiplying the estimated value L by the correction coefficient α as the thickness of the deposit layer 6, the estimation accuracy of the deposit layer 6 thickness during the operation of the blast furnace is further increased. improves.

  Note that the heat transfer state along the furnace wall may change with the progress of the blast furnace operation. Therefore, by measuring the deposit layer thickness Lm for each pause and updating the correction coefficient α, It is preferable to maintain the estimation accuracy of the kimono layer thickness.

  Since it is possible to accurately estimate the deposit layer thickness even during operation as described above, for example, means for adjusting the through-flow heat flow rate Q by changing the charge distribution to change the gas flow in the furnace Alternatively, it is possible to control the deposit layer thickness with high accuracy by using means for adjusting the stave casting surface temperature T0 by changing the stave cooling water flow rate.

  Further, even after the adhered layer is peeled off and the measurement part (51 in this example) on the front end side of the temperature sensor 5 is damaged, the adhered layer obtained from the temperature data measured until it is damaged By using the thermal conductivity λa of 6 as a known number, the thickness of the deposit layer 6 can be determined using the above formulas (1), (2), and (5) without using the above formulas (3) and (4). L (and Lc) can be obtained.

(Modification)
In the above embodiment, the example in which the measurement unit of the temperature sensor 5 has three points is shown, but two points or four or more points may be used. As the number of measurement points increases, the measurement accuracy improves, but the cost of the temperature sensor 5 also rises. Therefore, considering the balance between measurement accuracy and cost, it is recommended to use about 3 to 4 points in practice. Is done.

  Moreover, in the said embodiment, although the position of the measurement part 52 of the middle among the measurement parts of the temperature sensor 5 was made to correspond with the position of the surface of the stave casting 3, it is not necessarily limited to this, The stave casting 3 is suitably used. It is also possible to shift the position from the surface position to the inside or outside of the furnace. However, there is an advantage that the simplest analysis logic can be used to match the position of the middle measurement unit 52 with the position of the surface of the stave casting 3.

  Moreover, in the said embodiment, although the stave casting thermometer 4 and the temperature sensor 5 showed the example installed in the same horizontal surface, when installation on the same horizontal surface is difficult, install it shifting in the height direction. Also good.

In order to confirm the effect of the present invention, a temperature sensor similar to that described in the above embodiment is applied to the bottom stave casting of the shaft portion of the blast furnace (internal volume: 4900 m ³ ) installed in the applicant's Kakogawa Works. Attempted to estimate the thickness of the deposit layer was newly established at 8 locations every 45 ° in the circumferential direction of the blast furnace. As the stave casting thermometer, an existing one (having a measurement part on the outside of the furnace 50 to 100 mm from the surface of the stave casting; the position of the measurement part differs depending on the installation location in the circumferential direction of the blast furnace) was used.

  As a temperature sensor, in a protective tube made of stainless steel, with a MgO powder as a filler, it has a measurement part at each position of 5 mm, 25 mm, 45 mm from the tip of the protective tube (that is, in FIG. 1, d0 = 5 mm, d1 = d2 = 20 mm), and a non-grounded sheath K thermocouple was used.

  Here, d1 = d2 = 20 mm is based on the result shown in FIG. The figure shows the experimental results of simulating the heat transfer state when the temperature sensor is attached to the stave casting using a small heating furnace. Specifically, a steel material having a thermal conductivity equivalent to that of a stave casting (indicated as λ in FIG. 2) by using a temperature sensor having two measurement parts and variously changing the distance d between the two measurement parts. (A)), or refractory mortar (Fig. (B)) with the same thermal conductivity as that of the deposit layer, two measuring parts are arranged inside, and the temperature sensor tip side is kept at a constant temperature. The heat transfer experiment was conducted in a state where it was inserted into a heated small heating furnace. As shown in the figure, regardless of the difference in thermal conductivity between the surrounding material of the temperature sensor and the filler in the temperature sensor, the temperature gradient between the two measurement parts is the distance d = 20 mm between the two measurement parts. It was found that the maximum value was exhibited, and d tended to decrease as the distance from 20 mm increased. Based on this result, d = 20 mm where the temperature gradient was the largest was adopted.

  After the temperature sensor is installed during the rest period, the blast furnace is operated for a certain period, and the deposit layer thickness L is estimated without using the correction coefficient α in the above formulas (1) to (5) immediately before the next rest period. In addition, the deposit layer thickness Lm was measured by the means described in the above embodiment during the next wind break. Then, the estimated value L of the deposit layer thickness was compared with the actually measured value Lm, and the correction coefficient α = 0.45 was determined. The relationship between the estimated value Lc (= α × L) of the deposit layer thickness corrected using the correction coefficient α = 0.45 and the measured value Lm of the deposit layer thickness is shown in the radar chart of FIG. As shown in the figure, it was confirmed that the estimated value Lc of the deposit layer thickness matched the measured value Lm very well regardless of the orientation of the blast furnace.

  Therefore, in the subsequent blast furnace operation, the deposit layer thickness Lc was estimated using this correction coefficient α = 0.45. FIG. 4 shows changes over time of the stave casting temperature Ts, the temperature T1 on the most front side of the temperature sensor, and the estimated value Lc of the deposit layer thickness in a certain direction of the blast furnace during operation of the blast furnace. As shown in FIG. 6A, the stave casting temperature Ts fluctuates with time. Conventionally, the increase / decrease in the thickness of the deposit layer was estimated qualitatively only from the fluctuation with time of this Ts. Thereafter, as shown in FIG. 5B, the deposit layer thickness can be accurately and quantitatively estimated (measured) even during blast furnace operation, and a quick action can be performed.

FIG. 5 shows the relationship between the once-through heat flux Q determined by the above formula (1) and the deposit layer thickness Lc in the subsequent blast furnace operation. The curve in the figure is a regression curve obtained by polynomial approximation (in this example, cubic approximation). As shown in the figure, when the through-flow heat flux Q decreases from the higher side, the deposit layer thickness Lc gradually increases on the higher Q side than the inflection point of the regression curve. On the side where Q is low, the deposit layer thickness Lc tends to increase rapidly. The coordinates of the inflection point can be obtained by placing the second derivative F ″ = 0 obtained by differentiating the polynomial F of the regression curve twice, and the value of the coordinate is Q = 25700 kcal / (m ² · h) and Lc = 0.115 m, where 1 kcal / (m ² · h) = 1.163 W / m ² .

  Therefore, in the subsequent operation, by using this 0.115 m as the management target value of the deposit layer thickness Lc, it becomes possible to reliably prevent a sudden increase in the deposit layer thickness, and stable blast furnace operation over a long period of time. I was able to continue.

1: Iron skin 2: Thermal insulation material 3: Stave casting 4: Stave casting thermometer 40: Tip position 5: Temperature sensor 50: Tip position 51, 52, 53: Measuring unit 6: Deposited layer

Claims (2)

A method for measuring the thickness of a deposit layer adhering to the surface of a blast furnace stave casting,
A stave casting thermometer having a measuring portion in the stave casting, a plurality of measuring portions in the thickness direction of the stave casting, and at least one measuring portion of the plurality of measuring portions protrudes into the blast furnace; A temperature sensor installed through the stave casting so that at least one of the plurality of measuring portions is located in the stave casting,
Using the temperature data measured by the stave thermometer and the temperature sensor, a plurality of heat transfer including the thermal conductivity and thickness of the deposit layer as unknowns at each installation location of the stave thermometer and the temperature sensor A method for measuring the thickness of a blast furnace stave deposit layer, wherein the thermal conductivity of the deposit layer is calculated and the thickness of the deposit layer is calculated by simultaneously solving equations. The measurement method according to claim 1,
After the measurement part of the temperature sensor protruding into the blast furnace is broken,
Using the thermal conductivity of the deposit layer calculated by the method of claim 1 as a known number before the measurement part protruding into the blast furnace is damaged,
Using temperature data measured by the stave thermometer and the temperature sensor, a plurality of heat transfer equations including only the thickness of the deposit layer as unknowns at the installation locations of the stave casting thermometer and the temperature sensor are simultaneously provided. The method for measuring the thickness of the blast furnace stave deposit layer is characterized in that the thickness of the deposit layer is calculated by solving.

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