JPS60184606A - Supervising method of furnace bottom of blast furnace - Google Patents

Abstract

PURPOSE:To stabilize the operation and to obtain easily fundamental information for prolonging the life of the titled blast furnace by estimating easily the erosion and solidification layer lines of the furnace bottom with use of the boundary element method, and always grasping exactly the state of erosion and the distribution of solidification layers at the bottom. CONSTITUTION:The maximum temp of the furnace bottom is detected by a temp. sensor 6 furnished to the refractory material at the furnace bottom. The heat transfer at the furnace bottom is analyzed from said detected value with the boundary element method by using an axisymmetric body wherein the vertical axis of the furnace is used as the symmetry axis 1, and the erosion shape of the furnace bottom refractory material 8 is estimated. After detecting said maximum temp., the temp. is detected when the furnace bottom temp. is lowered. And the shape of the solidification layer of the melt formed on the furnace bottom refractory material 8 is estimated in the same way as above-mentioned on the basis of the detected temp. and said estimated solidification shape by using the boundary element method.

Description

[Detailed description of the invention]

(Technical part!l!f) Furnaces such as blast furnaces, electric furnaces, and glass melting furnaces that contain high-temperature molten material and promote reactions are collectively referred to as blast furnaces, and the lifespan of the furnaces and We hereby propose the development results for accurately understanding the original state of the hearth bottom, which reflects the operational status, through constant and accurate estimation updates during the operational period, and for preparing appropriate countermeasures. be. (Background technology) Taking a blast furnace as a typical example 2, we quickly and accurately estimate the distribution of the solidified layer that disappears as the corrosion of the refractory improves according to the erosion condition of the large refractory bottom, and evaluate the current state of the furnace bottom. Continuous monitoring is necessary in recent years as blast furnaces have become larger in pursuit of high productivity and operating conditions have become more severe, leading to faster extinguishment of the furnace bottom refractories and shorter furnace life ('t+'). Especially in the current situation of low economic growth, blast furnace operations are facing a strong trend, and in particular, it is possible to maintain stable operation, extend the life of the furnace, and reduce the unit price of pig iron. What is baking soda? 4! In other words, in order to ensure stable operation and extend the life of a blast furnace, the situation at the bottom of the furnace must be constantly monitored during blast furnace operation, and protective measures should be taken quickly and accurately to prevent erosion. It is essential to take measures against freezing, and at the same time, due to the implementation of Gφ protection measures and fluctuations in operational conditions, raw material +4Q on the eroded surface, annihilation repeats, hot metal, coke, brick fragments, etc. Mixed l of charge
):: f-1i', it is also essential to constantly grasp the distribution status of the A layer, and to determine measures for flattening the surface of the human body: V conversion, and to control the coagulation layer thickness and layer 19 distribution. (Prior art and problems) The corrosion line of the furnace bottom hard refractory, the 4fi line outside the layer thickness of the first layer of coagulation 1e, which elongates on the surface j of the refractory erosion, the solidified layer line (hereinafter referred to as 1. I'm taking it lightly and calling it the "f3 food solidified layer line."
J1: r? B) (Multiple thermocouples are arranged to calculate the heat transfer at the bottom of the furnace. Conventionally, to estimate the line of the eroded solidified layer at the bottom of the furnace, the actual temperature detected by thermocouples at each part of the furnace bottom and the markings are used.) One-dimensional heat transfer calculations or the finite element method was used as a two-dimensional heat transfer meter. It is impossible, and the bottom of the blast furnace is an axisymmetric object with the vertical axis of the furnace as the axis of symmetry (simply called an ``axisymmetric object'').
A two-dimensional heat transfer meter (a) is indispensable even if it is simplified as (i.e., -Director-
In general domain methods such as the method and the difference method, in the case of an axially symmetric problem, as shown in Figure 1, the axis of symmetry is set as 1, and the meridian section 2, for example θ = 00, shown by the extra line is divided into elements, and each element is Determine the variable (temperature) so as to satisfy the heat conduction equation. Therefore, to estimate the erosion line, first consider the meridian cross section 2 of the hearth bottom at the actual temperature measurement position as shown in Figure 2, and then calculate the erosion line appropriately. Assuming the solidified layer line 5, the region of the meridian cross section 2 in FIG. 2 is divided into information tree, and the temperature of each part is measured. In addition to the general erosion, the solid line 5 is the iron-carbon eutectic melt temperature (approximately 1150'U). Since h+ is considered to coincide with the line, this temperature of 1150° C. is applied to the boundary conditions at the five eroded and solidified layer lines, and bottom cooling conditions are applied to the other boundaries. FIG. 2 shows an example of the cutting results obtained by this method, and each isothermal line is plotted. Next, the calculated value at the position of the 7-crystallinity meter 6 immediately installed at the hearth bottom is compared with the actually measured value. The temperature range where there is a difference between them, e.g. 10℃
If it is larger, move the 1 layer 7 solidification j so line 5 a little ≠ desirable * t rp region 2 is divided again and repeat the above operation 1 ° all furnace bottom temperatures 1 ift, Repeat this process for wells where the measured values match within a certain range of 11 degrees to determine the eroded condensation layer diine 5. According to this method, the bottom lake 1 degree total 6 To estimate one eroded solidified layer line 5 from actual measured values at a certain point in time (Engineer 1
It takes a lot of steps (people) x (half a day) x (1 week). Needless to say, an electronic fortune-telling machine is your enemy,
Also, the number of inputs each time is very large, so a fairly large computer is essential. In addition, it would be complicated, if not impossible, to automatically move the erosion solidification layer line 5 and input the division of internal elements, but the algorithm to execute it would be complicated, and the internal In addition, unnecessary temperature calculations are added, resulting in a large calculation cost. In this way, it takes a great deal of time to estimate the erosion solidification layer line 5 at the bottom of the furnace using conventional domain methods such as the finite element method. Therefore, in the event of an abnormality such as a rise in the bottom temperature, it is extremely difficult to quickly estimate the bottom erosion situation and take prompt and accurate measures to protect the bottom membrane. ``It is impossible to take refractory protection measures in a timely manner and control the layer thickness distribution to stabilize operations. Therefore, it is impossible to manage the furnace body by grasping the situation at the bottom of each blast furnace at any given time, taking long-term protection measures to stabilize operations, and responding immediately in the event of an abnormality.
if1. It was. (Start of the idea) Under these circumstances, the inventor decided to convert an axisymmetric problem from a two-dimensional problem to a one-dimensional problem using a numerical calculation method called the boundary element method, which has recently begun to be actively researched. to 58
I saw it. In other words, as shown in Fig. 8, the proximal line break m+2
1. Divide the field line 4 (for example, the intersection line of the meridian cross section at θ = 0 and the boundary surface of the axisymmetric region) into elements, and on each element (i.e., line segment) 9, define the boundary corresponding to the heat conduction equation. Figure 4 shows an example of the heat transfer calculation at the hearth bottom obtained by the boundary element method and each '4F vortex line. As shown in Figure 4, the boundary element method By calculating only boundary line 4 (however, if the types of 11 elements are different, including those boundaries) by element division L2, the heat transfer problem can be solved, and the internal old man and tw are also old men. The disputed boundary values can be determined using the values of the variables, namely pain degree and heat flux. In this way, the boundary element method does not require element division of the inside of the region, that is, the furnace bottom brick 8, and it becomes possible to automate the estimation of the eroded solidified layer line 5 of the furnace bottom brick 8. Process of estimating the eroded solidified layer line 5 is the same as the above-mentioned finite element method, but by applying the boundary element method, the internal element division every time the eroded and solidified layer line 5 moves becomes unstable, and the calculation of the internal temperature also depends on the depth of the furnace bottom. c, #
By applying this calculation method, it takes only 1 to 2 minutes to calculate M (true erosion line: 1 in Figure 6, which will be described later).
Position 1: True solidified layer line: 14 in Fig. 12, which will be described later.
This not only reduces the number of man-hours and calculation costs, but also makes it possible to uniformly check the bottom of all blast furnaces in a steelworks, as well as speed up actions in the event of an abnormality such as a rise in bottom temperature. It is possible to make great profits such as extending the life of the blast furnace... (Objective of the invention) The purpose of this invention is to:
By utilizing the boundary element method, we can reduce the dimension of the heat transfer problem by one and reduce the axially symmetric problem to a one-dimensional problem. In this way, we can use this Jl to estimate the erosion bjt solid If1 line at the bottom of the blast furnace. The purpose of this project is to establish a method for monitoring the bottom of a blast furnace, which can be easily automated and can be used to manage the main line of the furnace and extend the life of the furnace. (Structure of the invention) This invention 1l-i: Monitoring the bottom of the bath ore furnace 41. ; When operating the furnace, the following conditions shall be met during the operation period of the furnace:
A method for monitoring the bottom of a blast furnace consisting of turning the edges. Step of detecting the furnace bottom fr, mouth (t)) Step of detecting the maximum hot water temperature of (a), (c)
Step 1 (d) of predicting the erosion shape of large materials at the bottom of the furnace by performing a heat transfer analysis using the boundary element method based on the humidity in (b) as an axisymmetric body with the vertical axis of the furnace as the axis of symmetry. A step of detecting the temperature when the hearth bottom temperature has decreased after step b); Using the method to reach the bottom of the hearth,
The process of performing heat transfer analysis as an axisymmetric body with the vertical axis of the furnace as the axis of symmetry and predicting the shape of the solidified layer of the molten material in the furnace that has been generated on the eroded furnace bottom support, all steps above 6. Specifically, it corresponds to the following steps. ■ Embed a number of temperature sensors in the refractory at the bottom of the blast furnace and/or on the outer surface of one large object. ■ The bottom of the blast furnace is an axisymmetric body with symmetry q4+1 about the central axis of the furnace, and the temperature sensor of Check [1]. ■ After the start of blast furnace operation, using the general 11 degree value of each sensor at a certain point when the candy 1 degree sensor in ■ showed the maximum temperature,
Using a numerical calculation method using the boundary element method, we perform a heat transfer analysis of the bottom of the blast furnace as an axisymmetric body with the center axis of the furnace as the axis of symmetry, calculate the calculated values at each sensor position, and calculate the measured temperature value. Determine the initial value of the search by using multivariate successive approximation alone or by this method using 8-level target intersection so that the difference with the value is smaller than the pre-given value, and reduce the search cape and enclosure. Then, by using an optimization method such as the modified quasi-Newton method, that is, a multivariate search method, the erosion line of the bottom refractory (the eutectic temperature of iron-carbon system 1150
℃ isothermal) f: Determine 〇(li) After the start of blast furnace operation, if the gutter 1 value of It is thought that there is a solidified layer on top of the solidified layer, and the solidified distribution line, i.e., the solidified / if line (iron-carbon eutectic rir1.degree. 1150°C isotherm) is determined in the same way as in ■. As described above, the erosion line of the M person at the bottom of the furnace and the distribution line of the solidified layer that ebbs and flows on the eroded surface of the large object are sequentially estimated over the entire period from blast furnace firing to blowdown. We will specifically discuss the calculation principle of the element method and the procedure for applying it to estimate the erosion solidification layer line at the bottom of a blast furnace, managing the furnace bodies of multiple blast furnaces, and ultimately stabilizing operations.By the way, the boundary element The method has various other names such as boundary integral method, boundary integral equation method, singular point solution method, Green's function method, and marginal integral finite element method, but the calculation principle, that is, the governing differential equation of the field, They are all the same in that they are reduced to an integral equation on the boundary, and then are discretized and divided into elements to calculate values using a method similar to the numerical solution known as the finite element method. includes all of them.We will describe the formulation of the axisymmetric potential problem (steady-state heat transfer problem) using the principle boundary element method, including the 11 dispersion and solution method. (11 formulation ip, shown in Figure 5) Considering a 114i1 illusion region Ω like this,
the! i1′ world is 1 side (=1′□−1−/“2tr8
). Governing equation of potential problem and boundary condition r+
; is expressed as follows. Governing equation: 2u(x)==1) ... (1) C code
C, u(9) Is it within Ω? ;1, Hodennoyal in point color, u<,7) tcR5,) Ir:LrJ-
, (7) Ren, potential and iA in PS score

[',
East, uo, qo indicate all 11 shells, ua and h
? -J: Circulation 1) There are 11 potentials and (heat) transfer coefficients. In the case of heat transfer problems, the Bodensoyal U is the temperature J&,
The i+IiL flux q becomes the heat flux. The integral equation on the boundary for the problem under consideration is given by the following equation (8
) is given by 0(!!□)-u(!!□)+,#,,u (,q)
・q'(4i, a/"=//q(e)・u'(σ, σ
) dr ・・・・・・(8) r −1, ~ Here, the older brother i and the older brother select an arbitrary point on r by 6ゎ and 1c(σ・
) ~ l is C(4□) = 0.5 when the boundary is smooth, and when the boundary is not smooth, the value can be indirectly determined from the equipotential condition by using the OM [mirror function u''( σ・σ)＼ or u＠(x□, flower) satisfies the following differential equation (4) corresponding to equation (1) in the infinite medium CI i, and is called the fundamental group. V"u"(x, x ) + δ(x-x, ) = 0 ・
--(4) ~l, ~ ~ ~l where ・X and X represent arbitrary points within Ω, and δ”, “i)
~1. ~ is the Dirac delta function. The solution of equation (4) for a three-dimensional isotropic object and Q'(Xi, )=θu(5, Otsu)/θn=(' tr
l<”) (”R/an) River...(6)°Here, R
= Ix -
This also holds true for the earth point d. In an axially symmetric problem, both the potential and the flux are constant regardless of the circumferential direction. Therefore, as shown in Figure 5, the equation (8
), (5), (a) is converted into a cylindrical coordinate system, discretized, and numerically solved. As shown in Figure 5, the point brother □
, the points of θ=θ′=0 corresponding to the older brother, respectively, are 2i, !
Let the outward unit normal at point 2 be = (n ,, n,
, na). Since θ = 0, Sn = 0, outward at point σ ~ 2
++ The unit normal Yu is expressed by north as follows. n=(n, n, n8)=(n1cosθ, 5□−θm
``B) ''...' (7) Also, since 1Ω is axially symmetrical, it is not the older brother □ (9 ('=0), but generality is not lost. Therefore, assuming 0=0, equation (5 ), (6
) in the normal direction derivatives of R and R are expressed in a cylindrical coordinate system as follows. R=l σ-σ, 1 ~, U= (r"+r"-2rr'cos#+(z-z')"
”] ...(8) However, σ = (r, θ, z) 1. Scarcity -, = (rio,
z'). Now, u on the intersection line S of r and the plane of σ = 0 including two axes,
Letting the values of q be u and q, respectively, since they are axially symmetric, the following will be obtained. 6i) Therefore, the cylindrical coordinate system expression of equation (8) is given by the following equation (11) = Ifr(1(,3) j u(2H) ・+ J l
dro ・----(zsu7', u'(σ, σ), q
``(!i, ?' is a cylindrical coordinate system expression ~1.
Discretization and solution Equation (11) is an integral equation regarding the potential U and flux qK on the intersection line S between r and the plane of θ=0 including the Z axis. Therefore, just like a two-dimensional problem, by dividing S into elements, a discretized algebraic equation is obtained, and by solving this, the problem is solved. However, the integral regarding u and q in equation (11) is the surface F of the rotating body. It must be done above, resulting in a double integral. Now, we divide S into N boundary elements, and the node t at node j
Suppose that u and q in the element are expressed as follows by using the function φ in 0, which is called 'f: uj, qj.0 Here, U and q are the nodes of u, ! : is a column vector of q. By substituting equation (12) into equation (11), the following )'tllWJ, algebraic equation is obtained. G, = //, φ (Tomoe)・u (q, t2−)
・l J l dI”c 'Beak...(16) C 〇Here, for example, the boundary element (line segment) S shown in FIG.
Due to the relationship between r and 2 of j soil and the variable conversion of 2, r is changed as follows. r = az+b = a・Δz,・t+az, -1−
b -...-(16) KoJ Here, ΔZJ'' Zj-+-□Z3, a, -b
represent the slope and intercept of element S at θ=0 plane. Using equation (16) and expressing a vector in g Sj ', r=(a・Δz, −t+az, 10b) cosθ
・1 ~ 3 J ~ + (a, -Δz ・-t+ azz ten b) 'sin
θ・Yo(ΔZj−t+zj)・Do・・・・・・(1
7). Here, 2. Self and run are X□ X 2. '
X a East: A medium-sized vector in one direction. Using this, rl in equation (9) and IJ+ in equation (11)
is expressed as follows. rl-(Δz/1.) (1-ak)...
(18) ~ ], ) ~ ~ IJ I =1. −(a, −ΔzJ−t+azj+ b
) −・−・(19)1・tdl' =lJl・d/
'o=lJl・dθ−dt, equations (5), (6)
, (sl, (!11.
14), Substitute into (15), θ=0~2π, t=0−
By performing all the integration between 1, ■(0, and GlJf
:a・Can be monovalent. z--For a boundary element on a certain plane, a) Equation (14), (,
+5). Concerning the boundary nodes of all, considering equations 1 to (13), I'i is 1111 of q can be defined between l'2 and I'3.V Kochuonzu 11.
itf, the 11th uncle is N 117i1 and the whole system -
Taka 4j, B type will be as follows. AX=F (20) Here, A is a coefficient matrix, and X and F are column vectors containing only unknown nodal quantities and only known -, respectively. It is sufficient to solve the equation (2o)'fcX. The potential at an arbitrary point X in Ω can be calculated by the following equation using the node Sho on the boundary ~l. The above calculation principle can be summarized as follows. ■ Create a weighted residual i expression by combining the governing differential equation (Laplace equation) (1) of the steady heat transfer problem with the boundary condition (2). φ) Convert this tIfmitsuki remaining bank expression into an integral equation (8) on the boundary. ◎ Considering i1MII symmetry, convert equation (3) into total cylinder coordinate thread expression (11) 0 @ In order to numerically solve equation (11), the boundary of the region When dividing 5゛L plane I゛. into elements, the formula (18
) is the discretized algebraic equation of 44. The valley was divided in order to do so. Express j as a parameter using a vector (Equation (J?)). [F] Using equation (17), equations (14) (15) ζ
j・double integral can be changed by 1ft, and numerically calculating these values becomes EJ function. ■ Considering Equation (13) for each element I', the sashiki force equation (20) with unknowns (C, N, number of equations)...
I, this is h7, 'I? , all dlls in the world
・The degree and heat flux are determined 0 ■ Inside the area Ω (M+! IM is the swamp on the boundary ・1 degree,
Using the heat flux, it is calculated by equation (21). Now, since the method of estimating the erosion line and the solidified debris □ line using the boundary element method is the same as J1, the procedure for calculating the erosion line ilg>1 will be described below as an example. (By the number 11 word 11 method based on the 11 boundary element method,
The heat transfer interval i, ・i'l ('1. The number, that is, the degree of resignation and the heat flux are unrelated in the circumferential direction, and the problem is solved with one meridional section of the area as symmetry, so it is a two-dimensional problem. ) into an integration problem on the boundary of the meridian section of the axisymmetric region (the boundary can be represented by a line segment, so it becomes a one-dimensional problem)〇(2) The bottom of the blast furnace (brickwork section 8) Since ρ1 is considered to be an axially symmetric body, the boundary 4 of this meridian cross section (including the position of the thermometer 6 buried in the hearth bottom) as shown in Fig. 6 is defined as a minute boundary element (line segment) 9. Divide into. (8) Both end points 12 of the boundary element 9 on the erosion line 5 are considered as movement points, and the maximum, intermediate, and minimum values of the movement direction and movement distance from a certain arbitrary point are given in advance for each. Therefore, the erosion line 5 provides an iron-carbon system eutectic temperature of 1150° C. as a boundary condition for a node lO on the 0 boundary element 9, which is considered to connect the end points 12 of the boundary element 9. (4) External cooling conditions (heat removal or cooling heat transfer coefficient) for nodes 10 on elements 9 on other external boundaries
give.゛(5) Each moving distance of each moving point 12 in (8) above (8
For example, the orthogonal array shown in table @1 (for example, "Design of Experiments (Part 1)" by Gen Taro, 8th edition, P527 (1)
076) According to Maruzen), 86 combinations, that is, 86 erosion lines 5 are created by connecting 8 levels of movement positions of each movement point 12. 2E ■ Seven is seven; : C: ::True 1 In general, if the number of moving points is n, each point has 3 water orchid places 1i1. Since there is i:, the total number of combinations is 3n, which is very confusing. However, using the target table above, 86. If we compare +19 combinations, it is 1, and each moving point is 12.
Which of the 8 water wall positions is optimal for each VC?
In other words, at which level the evaluation function described in C can be fully determined, given the condition that the evaluation function described in C is the most <IN''8 plus (Ii) (X3B of nl). Point 10 on the valley boundary is given one of the following boundary conditions: temperature, heat b1 shi east, i] ru, or heat transfer] gradation i itomori, so the interval han is Against >t'M
＜I can do it. In other words, it is possible to eliminate the problem by using the boundary '& search method. IIi point 1o and the heat r door bundle are determined. (7) Using the temperature 11BI at the node 10 on each boundary layer 9 determined in this way and the temperature in the heat flow, each temperature a(6) bl
Calculate the temperature at lii for the case (5) of 36 jI9 t). (Calculate the predetermined evaluation function values for the 36 cases in 81 (5). For example, calculate the square of the difference between the actual measured value and the calculated value at each temperature cutting 6 position by the actual measured value. Total 6
(hereinafter referred to as "error sum of squares") is added to the 36 sets of erosion lines 5. (9) Next, for each moving point 12, the first . Second. In order to fully determine which of the 8th levels (positions) is optimal, the evaluation function values (sums of squared errors) of each level are compared. For example, in the case of mobile fishmonger L, the combination black 1.4,7,1
0. la. Add all the error sums of squares for 16.19, 22, 25, 2.8, and 31.84 to obtain the sum of the error sums of squares for the first level. Second. The same applies to the third level. For each moving point 12, compare the sum of error squares of three levels,
The level with the smallest value is the optimal position of each moving point 12 (
level). (10) (Optimum position ff of each moving point 12 determined in 91: Connect to determine a new invasion line 5, and repeat the two series of ((i) and (7) d゛1' The value function value (sum of squared errors)' is calculated as υ.If this satisfies the condition (for example, it becomes smaller than a predetermined small value), the true erosion line (1-1 in Figure 6) 1), but normally the step of 111jI does not satisfy the condition, so the process of () to (9) is repeated. (11) When repeating the process of (31 to (9)), each of the previous steps The level width of moving point 12, that is, the difference between the maximum value and the minimum value of the moving distance from the point 12, is calculated from () to 10
Reduce by a certain percentage determined from experience between 0% and w
Determine the iL level width. A total of three new levels (positions) are determined for each moving point 12 by adding or subtracting the level of the valley moving point 12 determined by this new water q width % (9) for each moving point 12. That is, for each moving point 12,
Determine the new maximum, intermediate, and minimum values for the distance traveled from a given point. In this way, narrow down the level width to be compared and use (
Repeat the process from 3) to (9), and repeat the steps above for new (12). If you repeat the process from (3) to (9) a total number of times, the level width of each moving point I2 will become sufficiently small, and finally A true erosion line (1 m in FIG. 6) that satisfies the conditions, that is, the evaluation function value is smaller than a predetermined value, is obtained. FIG. 7 schematically shows the process in which the level width of each moving point 12 is successively reduced and the erosion line is determined. In this way, the process of (3) to (12), that is, the multivariable successive approximation method using orthogonal light, makes it possible to estimate the true erosion line 11 with considerable accuracy, but the modified W1 quasi-Newton method (For example, rFACoMFORTRAN S
SL It User Guide Ministry J, P, +or<1oso
) Fujitsu] and the Simbrex method (for example, J. Kowalik and M, R. Osborn [Nonlinear Optimization Problems J, P. 27, 70) Baifukan)
It is possible to estimate the tool erosion line 11 even more precisely by combining it with a nonlinear multivariate search method such as . Below - Revision rate Newton as an example? #
&(ttFll- を-人=”=IFify;m-first-
・(The process of estimating the erosion line using the multivariable successive approximation method using Al i# intersection is repeated several times depending on the initial level width. In other words, the initial water (■ The larger the width, the greater the number of times.) Bl Each determined moving point] 2 new level (position)
is the initial value, and '/2.' of the level width of the previous step. '(r first s'v+-c The search is started using the movement range given without direct adjustment as the search range of each movement point 12 (Fig. 7). (C1 convergence condition is satisfied (all movement points! 2, k
The difference between the Jt positions that is determined by the +1st search becomes smaller than a predetermined small value, that is,
The search is terminated at point H,'i (where the evaluation function reaches an extreme value). In general, in the nonlinear multivariate search method, if the initial value is not given near the extreme value of the evaluation function, that is, the erosion line 5' at the beginning of the search is near the erosion line 11 of β9.
f: If not set, the search will not succeed. Therefore, setting the initial value and search range using the multivariable successive approximation method using orthogonal arrays is the key to a successful search. However, if only the multivariable successive approximation method using the orthogonal array is used, the level values that can be searched are limited as described above, and there is a limit to the improvement of accuracy. Therefore, it is possible to correctly estimate the true erosion line]1 with considerable accuracy just by searching using the multivariable successive approximation method, but in order to estimate even more accurately, it is necessary to use the nonlinear multivariable search method in combination as described above. is more desirable. If all the methods described above are used, the total time required to estimate the true erosion line 11 from the temperature value at a certain time is 1 hour.
2 minutes, it is possible to display the estimated furnace bottom erosion line of the buried surface of the thermometer 6 on-line from the momentary foot measurements and immediately notify the furnace operator. This makes it possible to constantly grasp the state of erosion in each part of the bottom of multiple blast furnaces, and to take short-term and long-term protection measures for the eroded parts quickly and precisely. The layer thickness distribution line +4 (hereinafter referred to as "F") of the solidified layer that forms and disappears on the corroded surface of the refractory can be estimated in exactly the same way by the method described above. It is. Since the refractory at the bottom of the furnace gradually wears down after the blast furnace is fired, the side temperature value of the side temperature sensor 6 of each part (xi) gradually rises in the long term, but in the short term it depends on the blast furnace operating conditions. Changes in and l1
llj Depending on the amount of fireworks, the erosion surface of silk big fish;・Hard M
i grows and the side temperature value increases to 1 degree Fahrenheit. It is known that the IV solid bed distribution has a large effect on blast furnace operation between tapping and slag, and stabilizing blast furnace operation by controlling the distribution has become a serious issue. .With this one-day process, the estimation of the coagulation line 14 can be completed in a short period of time, similar to the estimation of the solidification line 11, and it is possible to go online in 5J hours. For this reason, it is necessary not only to set a fixed fit for refractory protection measures, but also to determine the momentary coagulation layer thickness and layer Jt-7 distribution.
The I example becomes i, 'il' j city, and the stabilization of the blast furnace] ■ industry, and ultimately the blast furnace's I life's ζ Hj; JjH is achieved by. As mentioned above, it is similar to the conventional method as far as the judgment is based on the reading of the thermometer, but even if the reading is the same, the thickness of the remaining brick may differ depending on the cooling conditions, It was difficult to quickly determine whether the shape of the building was eroded and how dangerous it was. That is, in the past, a large amount of man-hours were required off-line to predict the state of erosion each time the temperature at each part of the furnace bottom rose, making it difficult to take protective measures quickly and accurately. However, it was nearly impossible to constantly monitor the distribution of the solidified layer due to the enormous amount of time required for estimation. Example: Bottom refractory erosion line 11 for a certain actual measurement value of a thermometer 6 buried in the bottom of a large blast furnace of 5,000 tons of Nissan pig iron.
An example of estimation is schematically shown in FIG. A meridian cross section including the position of the hearth buried temperature gauge 16 is considered, and its boundary is divided into 4 parts and 9 parts. The inner surface of the brickwork 8 at the time of blast furnace construction was set as the search range for the erosion line 5, and the boundary node 10 above it was given a boundary line f1 of 11500, while the boundary node 10 on the outer surface of the bottom brick 8 was give conditions. The temperature and heat flux at all the boundary nodes 10 and the temperature at the position of the thermometer 6 are measured by applying the boundary element method a. do. When the actual measured value of the temperature 316 and the old p value satisfy the pre-given conditions, the movement of the erosion line 5 is reversed by a series of search methods, and as a result, the result (as shown in Fig. 5) is obtained. The true erosion line J1 is determined. The initial position 16 of the erosion line 5 and the determined erosion line l]
If the location of
It will take about 0 seconds. Specifically, the above-mentioned method was applied to j females, and the h-8 fruits were harvested. 8 to 10 show the erosion line Il'z obtained by the multivariable successive approximation method using orthogonal light. Figures 8 to 10 respectively show the 1st to The difference was 5.2% on average. The total calculation time was about 85 seconds using a FAOOM M-200il calculator. In order to improve the estimation accuracy, the modified quasi-Newton method was used from the second step as described above. Figure 11 shows the erosion line 11 obtained by searching by switching to As a result, the calculation time is approximately 2 minutes, but if the estimation is carried out constantly, the initial search range can be narrowed down and the required time will be significantly reduced. Figure 12 shows the solidified layer line 14 obtained by the same method when the measured value of the buried thermometer 6 decreased. These are the results obtained by applying the method and switching to the revision rate Newton method.The average error was 3.2%, and the total time for one hour was about iso seconds. The time required increased due to the increase of 1j. If the condensed layer line 14 was always estimated in the same way as the erosion line 11,
Individual estimates (9i low time is about 10 to 30 seconds/I ()
It becomes. With conventional methods, the true erosion line 11 can be removed in such a short time.
4. It is impossible to fully estimate the erosion state and the coagulated layer distribution state, so it is useful for displaying the erosion state and coagulated layer distribution state, for quick maintenance in case of an abnormality, and for controlling the distribution of the coagulated layer. In addition to stabilizing operations through installation, it can also be used for long-term furnace tube use in multiple blast furnaces! (It is obvious.) Advantages of the invention 1. It is possible to properly clamp the bottom of the furnace at all times, regardless of the state of erosion and the distribution of the solidified layer, so it is possible to protect the bottom of the furnace in both the long and short term. Measures can be taken quickly and accurately, and basic information on how to stabilize blast furnace operations and advantageously extend the life of the blast furnace can be obtained easily.

[Brief explanation of the drawing]

First Hi1ba, ril by finite element method isotube one area method
) - An explanatory diagram showing the pirates (shaded area), Figure 2 is a hearth temperature distribution diagram showing an example of hearth heat transfer calculation using the finite element method, and Figure 8 is a calculation area using the boundary element method. (Cross-section boundary + tj
Figure 4 is a hearth bottom temperature distribution diagram showing an example of furnace 1 heat transfer calculation using the boundary function method. X2=
Intersection with 0 (θ=0) plane, Vi! An explanatory diagram showing S,
Figure 6 is an explanatory diagram schematically showing the process of estimating the erosion line at the bottom of the blast furnace. Figure 7 shows the process in which the level width of the moving point is gradually reduced and the erosion line is determined, and the multivariate search method. Figure 8 is an explanatory diagram showing the search range and initial J value when switching. Figure 8 is an explanatory diagram showing the erosion line obtained by applying the multivariable successive approximation method using orthogonal light once. Figure 9 is , an explanatory diagram showing the erosion line borrowed by twice using the multivariable successive approximation method using the intersection table; Figure 11 is an explanatory diagram showing the erosion line obtained by applying the method X3 times consecutively.
1 consecutive suitable month, and limit the initial value and search range of the search,
An explanatory diagram showing the erosion line that has been reduced by applying the reduced trowel modification @ J quasi-Newton method. After limiting and reducing the initial value of the search and the search range, the revised quasi-Newton method is used to obtain the 1st situation showing 21 lines.1. Axis of symmetry 2...Meridian cross section (rip j'), area to be shifted 3 Cylindrical seat (vote system (r, (7, z)) 4...f-fine cross section boundary line (area to be totaled η) 5 Furnace Jj'C' Rojin erosion line or coagulation layer line (J
150'0 isotherm) To... hearth bottom jip setfuku 7 degrees 1 7... etc. black line 8...
・Furnace bottom 1 mj Fire f proboscis 9... Boundary element 1 S. Moving point) 18...Erosion, end point of the boundary element on the boundary other than on the solidified layer line 14,...Determined solidified layer line] 5...Inner surface of refractory during construction 16...Tap hole level. Patent applicant: Kawasaki Steel Manufacturing Co., Ltd. Representative patent attorney: Hide Sugi Toshiaki 11.4. . Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 King: Water rate range: ) year 4'7r i? 'l Application No. 374/75
No. 2, Name of the invention Method for monitoring the bottom of a blast furnace 3. Person making the amendment A. 11. - No. 11°L:'1 Applicant (125) Kawasaki Steel Corporation 5°6, Subject of amendment The "Detailed Description of the Invention" column of the specification, Drawing 7, and the contents of the supplement (as attached) ) Correct "original condition" in line 8 of page 2 of the specification to 1. Current condition. 2 W for “Each isotherm line” on page 5, line 8 of the same page to 1 “Each isotherm line 7”
J Correct. 3. Correct ``Mid line J'' in line 9 of page 7 of the same page to ``meridian J,'' and correct ``1 each isotherm line'' in line 14 of the same page to ``each isotherm line 7.'' 4 On page 9, line 15 of the same page, 1 "return" is corrected to "return". 5. Correct the following on page 14, lines 1 and 2. r c(4i)-u(2)+ff1-u(a)-q'(
ai, a) dr-f, fI-q (older brother), uo (older brother i, older brother) d1'... (3) 16 "Brother,
(θ-〇)'' is corrected to 1-5 (θ'-0n). 7 Correct 'S-J to 'Foj' on page 18, line 10 of the same. B same @ page 22, line 2 Correct the line ``Symmetry'' to ``Object''.Among the 9 drawings, correct ``Figures 1 to 6'' as shown in the attached correction diagram.

Claims (1)

[Scope of Claims] t. A method for monitoring the bottom of a blast furnace, which comprises repeating the following steps during the operating period of the furnace when the furnace is operated while monitoring the bottom of the blast furnace. (a,) A process of detecting the hearth bottom temperature using a number of temperature sensors installed inside the hearth refractory and/on the outer surface of the straddled hearth refractory, (bl detecting the maximum temperature of (a) (C) (
From the temperature of bl to the furnace bottom using the boundary element fFi, conduct heat transfer and deweighting as an axisymmetric body with the vertical axis of the furnace as the axis of symmetry, and predict the erosion shape of the furnace bottom surface 1 fire. , (dl A step of reproducing the temperature when the furnace bottom temperature becomes low after the step of (b), and (e+ (humidity in (1) and furnace bottom surface j predicted in (c)
Based on the eroded shape of the large fish, we use the boundary concubine method to reach the bottom of the furnace, and create 4K as an axisymmetric body with the vertical axis of the furnace as the axis of 4dl.
A process of performing n's iQ'f analysis and predicting the solidification (61 layer shape) of the in-furnace melt produced on the eroded hearth bottom refractory.