JP2000256759A - Method for estimating progressing condition of sintering reaction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the progressing condition of sintering reaction in a Dwight Lloyd type sintering machine in high accuracy. SOLUTION: The temp. flow rate and components in the exhaust gas in plural wind boxes 7, 7,... in the Dwight Lloyd type sintering machine, are measured, and positions and shapes of a coke ignition line and a solidification completing line are estimated from the obtd. measured values. Since the position and the shape of the coke ignition line regardless of the coke distribution in the inner part of the raw material layer can be estimated, the progressing condition of the sintering reaction of the raw material layer can be estimated in the high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for estimating the progress of a sintering reaction in a Dwyroid type sintering machine.

[0002]

2. Description of the Related Art The sintering process of a Dwyroid type sintering machine is as follows.
The air above the raw material layer is sucked downward to burn the coke mixed in the raw material, and the heat generated here promotes the sintering reaction and melting reaction between the raw ore particles and cools it As a result, a sintered ore having a high porosity and a mineral composition different from that of the raw iron ore is obtained. Since the properties of the sinter are strongly affected by the progress of the sintering reaction, it is essential to control the progress of the sintering reaction in the sintering process in order to stabilize the quality.

FIG. 10 is a schematic sectional view of a raw material layer showing the progress of a sintering reaction by a Dwyroid type sintering machine. In the figure, reference numeral 20 denotes a raw material layer, which is transported in a direction indicated by an arrow. The raw material supplied to the sintering machine is ignited by an ignition furnace 4. On the downstream side of the ignition furnace 4 in the transport direction, the air above the raw material layer 20 is sucked downward by a plurality of window boxes 7, 7... As a result, the sintering proceeds with the transport of the raw material layer 20, and the upstream end of the raw material layer 20 in the transport direction is constituted only of the raw material zone a in which the unmelted raw material is present as it is. On the downstream side after 4, the solid temperature of the raw material rises due to the combustion of coke breeze, and the red tropical b, which is partially melted and in a solid-liquid coexistence state, after the completion of the coke combustion, the solidification of the molten raw material starts. The sinter zone c in which the sinter is generated is completed, and the ratio of the sinter zone c increases toward the downstream side, and the downstream end portion is constituted only by the sinter zone c.

For this reason, the coke ignition line d, which is the boundary between the raw material zone a and the red tropical zone b, extends from the upstream end of the upper surface of the raw material layer 20 in the conveying direction, which is the ignition position, to the firing point f in the middle of the lower surface in the conveying direction. The solidification completion line e, which is a boundary between the red tropical zone b and the sintered ore zone c, extends from the ignition position to the solidification completion point g downstream of the firing point f on the bottom surface. It is formed without intersecting with the ignition line d.

The progress of sintering can be grasped by determining the shapes of the coke ignition line d and the solidification completion line e. And JP-A-55-79838.
The publication discloses a method of estimating a coke ignition line d from the temperature, flow rate, component, and pressure of exhaust gas in a plurality of wind boxes and changing a coke combustion rate so as to optimize the shape. ing.

The sintering point f is determined in accordance with Japanese Patent Laid-Open No. 55-79.
In addition to the determination by the method disclosed in JP-A-838, it can be determined as follows. That is, the exhaust gas temperature distribution in the machine direction is determined, and the exhaust gas temperature
A cubic curve is obtained by approximating the following equation, and a tangent at the inflection point of the cubic curve is defined as a temperature rising line. The heating line;
The firing point f can be estimated as an intersection with the reference temperature A determined by the structure of the equipment and the exhaust gas temperature measurement position.

[0007]

In the conventional method for estimating the progress of the sintering reaction as described above, it is necessary to measure the temperature, flow rate, components and pressure of the exhaust gas in order to estimate the coke ignition line d. However, there is a problem that it takes much trouble. Also, when calculating the coke ignition line d from the coke combustion rate, the distribution of coke inside the raw material layer is assumed to be uniform, so that it matches the actual process of positively generating particle size segregation as a measure for ventilation. And the accuracy of the estimation is low.

Therefore, the inventors of the present application have a proportional relationship between the distance from the surface of the raw material layer to the combustion position and the cumulative value of the exhaust gas flow rate. It has been found that by connecting the combustion positions at a plurality of positions, the coke ignition line d can be obtained regardless of the distribution of coke inside the raw material layer. Further, there is a problem that the solidification completion line e cannot be estimated, and the grasp of the progress of sintering is incomplete.

Accordingly, the inventors of the present application have determined that the reference temperature B determined by the temperature rising line, the structure of the equipment, the exhaust gas temperature measurement position, and the air leakage characteristic near the downstream end of the strand.
And found that the solidification completion point g can be estimated as an intersection point, and there is a proportional relationship between the glowing time of the raw material and the cumulative value of the calorific value of combustion, and the length of the length of the red tropical zone obtained from the glowing time is determined. It was found that the coagulation completion line e was obtained from the obtained coagulation ignition line d and the obtained coagulation completion point g.

The present invention has been made based on such knowledge, and it is an object of the present invention to provide a method for estimating the progress of a sintering reaction including the solidification completion line e with high accuracy. Aim.

[0011]

According to a first aspect of the present invention, a method for estimating the progress of a sintering reaction is to ignite a raw material containing coke breeze at a raw material ignition position on the surface of a raw material layer while transporting the raw material layer.
By sucking the gas in the raw material layer from the lower side of the raw material layer on the transport downstream side from the raw material ignition position, the sintering reaction progress estimation method in the Dwyroid type sintering machine that advances the sintering reaction, Measure the exhaust gas temperature and exhaust gas flow rate at a plurality of locations where the sucked gas is exhausted to the outside of the sintering machine, and estimate the position and shape of the coke ignition line inside the raw material layer from these measured values. Features.

The method for estimating the progress of the sintering reaction according to the second invention measures exhaust gas components at a plurality of locations where the evacuation is performed, and determines the measured values, the estimated position of the coke ignition line in the raw material layer, and The position and shape of the solidification completion line inside the raw material layer are estimated from the shape.

According to the method for estimating the progress of the sintering reaction according to the present invention, the exhaust gas temperature, the exhaust gas flow rate, and the exhaust gas component in a plurality of wind boxes are measured, and the exhaust gas temperature distribution in the longitudinal direction of the sintering machine is measured. Then, a firing point and a solidification completion point are obtained from this and the reference temperatures A and B unique to the equipment.

The cumulative value of the exhaust gas flow rate is obtained from the obtained firing point and the measured value of the exhaust gas flow rate, and each window is determined from the proportional relationship between the distance from the surface of the raw material layer to the combustion position and the cumulative value of the exhaust gas flow rate. By obtaining the combustion position in the box and connecting the obtained combustion positions, a coke ignition line is always obtained with high accuracy regardless of the distribution of coke inside the raw material layer.

Therefore, in order to estimate the position and shape of the coke ignition line, only the measured values of the temperature and the flow rate of the exhaust gas are required. Do not need. Further, from the firing point and the measured value of the exhaust gas component, the cumulative value of the calorific value of the raw material is obtained. The length of the red tropical zone is determined, and the solidification completion line is obtained by adding the determined red tropical length to the coke ignition line. By additionally considering the solidification completion point, a more accurate solidification completion line can be estimated.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing a configuration of a sintering process in which a sintering reaction progress estimation method according to the present invention is performed.

In FIG. 1, reference numeral 2 denotes a plurality of pallet trucks provided on a strand which is driven to rotate along a predetermined path and connected endlessly. The raw material is supplied to the pallet truck 2 at the upstream end portion in the transport direction, and the raw material is transported in one direction by the movement of the strand while rotating. At the same time, on the upper side of the pallet truck 2,
A feed hopper 3 for supplying raw materials is provided at a position on the upstream side in the transport direction.
Further, ignition furnaces 4 are arranged slightly downstream of the feed hopper 3, respectively.

Further, various raw material tanks 5a, 5b,.
The raw ore and the coke breeze to be used as fuel are mixed in the mixer 6 and then supplied to the feed hopper 3.

On the other hand, on the lower side of the pallet truck 2 from the vicinity of the ignition furnace 4 to the downstream end in the transport direction, a number of wind boxes 7, 7,... The pipe 8, the exhaust heat recovery facility 9, the dust collector 10, and the exhaust fan 12 are connected via the intake fan 11. , An exhaust gas analysis probe 13, an exhaust gas flow meter 14, and an exhaust gas thermometer 15
The exhaust gas analysis probe 13 is attached to an exhaust gas component recording device 16, the exhaust gas flow meter 14 is attached to an exhaust gas flow recording device 17, and the exhaust gas thermometer 15 is attached to an exhaust gas temperature recording device 18. And the exhaust gas component, flow rate,
And the temperature are continuously recorded and held. The exhaust gas analysis probe 13 can detect the concentrations of CO and CO ₂ contained in the exhaust gas. Further, the exhaust gas component recording device 16, the exhaust gas flow rate recording device 17, and the exhaust gas temperature recording device 18 are connected to a computer 19 for performing a process of estimating the progress of the sintering reaction. C contained in
The respective concentrations of O and CO ₂ , the exhaust gas flow rate and the exhaust gas temperature are input.

With the above configuration, each raw material tank 5a, 5
The raw ore and coke breeze are cut out at a predetermined ratio from b,..., 5n, mixed by the mixer 6 and stocked in the feed hopper 3 as raw material. Next, the raw material is supplied to the mining hopper 3
Thus, the raw material layer is supplied onto the pallet truck 2 traveling in the direction indicated by the arrow in the figure, and a raw material layer having a predetermined thickness is formed. The raw material layer formed on the pallet truck 2 is transported with the movement of the pallet truck 2 and, when reaching the lower part of the ignition furnace 4, is ignited by coke breeze distributed on the surface of the raw material layer.

Air is sucked by the intake fan 11 through the dust collector 10, the exhaust heat recovery facility 9, the main intake pipe 8, and each of the wind boxes 7, and the air flows from the upper side to the lower side of the raw material layer. As a result, the coke breeze in the raw material layer is sequentially burned from the upper portion to the lower portion from the ignition position to the downstream end in the traveling direction of the strand. The reaction is promoted, and the entire raw material layer becomes a massive sintered ore having a high porosity. The fired sintered ore is taken out from the downstream end of the strand.

The exhaust gas analysis probe 13, the exhaust gas flow meter 14, and the exhaust gas thermometer 15 installed in each of the wind boxes 7 are provided with the respective concentrations of CO and CO ₂ in the exhaust gas in the wind box 7. The exhaust gas flow rate and the exhaust gas temperature are detected, and the detection results are output to the corresponding exhaust gas component recording device 16, the exhaust gas flow recording device 17, and the exhaust gas temperature recording device 18, respectively. The exhaust gas component recording device 16, the exhaust gas flow rate recording device 17, and the exhaust gas temperature recording device 18 record the respective input results.

FIG. 2 is a graph showing the temperature distribution of the exhaust gas passing through the raw material layer in the machine direction of the sintering machine, and FIG. 3 is a graph showing the flow rate distribution of the exhaust gas in the machine direction of the sintering machine. FIG. 4 is a graph showing the components of the exhaust gas in the machine length direction of the sintering machine. In FIGS. 2, 3, and 4, each vertical axis indicates a temperature, a flow rate, and a component, and each horizontal axis indicates a position in the machine length direction. The exhaust gas temperature has a substantially constant value from the ignition position to the firing point, rises sharply from above the firing point, and falls gradually after exceeding the solidification completion point. The exhaust gas flow rate gradually decreases from the ignition position to the firing point, and rapidly increases after the firing point. Further, the respective concentrations of CO and CO ₂ in the exhaust gas are almost constant from the ignition position to the firing point, and after the firing point, the respective concentrations rapidly decrease.

The respective data input to the exhaust gas component recording device 16, the exhaust gas flow rate recording device 17, and the exhaust gas temperature recording device 18 are output to a computer 19, and the computer 19 Based on the above, the progress of the sintering reaction is estimated according to the following procedure.

FIGS. 5, 6 and 7 are flow charts showing the process of estimating the progress of the sintering reaction according to the present invention. A value α that is appropriately larger than the exhaust gas temperature at the ignition position is determined (step S1), and x = 0 (step S2). Exhaust gas temperature GT at the position of the x-th wind box 7 after ignition
It is determined whether (x) is greater than α (step S)
3) If it is smaller than α, x is incremented (step S4), and the processing of step S3 and subsequent steps is repeated.

On the other hand, in step S3, G when x = x1
If it is determined that T (x) is larger than α, the distribution of GT (x) for x after x1 is three-dimensionally approximated to obtain a cubic curve y = Gt (x) (step S5). The x coordinate x2 of the inflection point of the cubic curve y = Gt (x) is obtained (Step S6), and the tangent of y = Gt (x) at x2 is obtained.
This is defined as a heating line y = Ut (x) (step S7).

A reference temperature A, which is determined in advance based on the structure of the equipment and the position at which the exhaust gas temperature is measured, and the temperature rising line y = U
An intersection with t (x) is obtained, and this is set as a firing point f (step S8). Further, a reference temperature B previously determined based on the structure of the equipment, the exhaust gas temperature measurement position, and the air leakage characteristics near the downstream end of the strand, and the temperature rise straight line y = Ut (x)
Is determined as the solidification completion point g (step S9).

Next, i = 0 is set (step S10), and the distance FF from the surface of the raw material layer at the ignition position to the combustion position is set.
D (0) [mm] is set to 0 (step S11). i is incremented (step S12), and the distance FFD (i) [mm] from the surface of the raw material layer to the combustion position at the position of the i-th wind box 7 after ignition is calculated by equation (1) (step S13). FFD (i) = FFD (i−1) + HT × Q (i) / QT (1)

Since there is a proportional relationship between the distance from the surface of the raw material layer to the combustion position and the cumulative value of the exhaust gas flow rate, equation (2) is obtained, and from this, equation (1) can be derived. FFD (i) = HT × {Q (i) / QT} (2) where HT [mm] is the raw material layer thickness, Q (i) [Nm ³ /
[Min] is the detected exhaust gas flow rate at the position of the i-th wind box 7 after ignition, and QT [Nm ³ / min] is the accumulated exhaust gas flow rate from ignition to the firing point f.

When the p-th window box 7 from the ignition is located at the firing point f, it is determined whether or not i is less than or equal to p (step S14). If it is determined that i is less than or equal to p, , And the processing from step S12 onward is repeated. If it is determined that i is greater than p, j = 0 is set (step S15), and the glow time dt (0) at the ignition position is set.
[Minute] is set to 0 (step S16). j is incremented (step S17), and the complete combustion amount Bp of carbon contained in coke in the raw material per unit time at the position of the j-th wind box 7 after ignition is calculated from the equation (3).
(J) [mol / min] is calculated (step S18). Bp (j) = Q (j) × ([CO ₂ ] / 100) × γ × 1000 / 22.4 (3) where [CO ₂ ] [%] is the CO ₂ concentration in the exhaust gas, The coke weight inside is RCKR [T / H], the carbon content of the coke is ηc [%], and the limestone weight is RL.
It is assumed that γ as MR [T / H] is a constant obtained by the equation (4). γ = (RCKR × ηc) / {RCKR × ηc + RLMR × (12/100)} (4)

Next, from the equation (5), the incomplete combustion amount Bi (j) of carbon contained in the coke in the raw material per unit time at the position of the j-th wind box 7 after ignition is calculated.
[Mol / min] is calculated (step S19). Bi (j) = Q (j) × ([CO] / 100) × 1000 / 22.4 (5) where [CO] [%] is the CO concentration in the exhaust gas.

Further, the thermal decomposition amount Ml (j) [mol / min] of lime in the raw material per unit time at the position of the j-th wind box 7 after ignition is calculated from the equation (6) (step S20). Ml (j) = Q (j) × ([CO ₂ ] / 100) × (1-γ) × 1000 / 22.4 (6)

From equation (7), the combustion heat value E per unit time at the position of the j-th wind box 7 after ignition is obtained.
(J) Calculate [kcal / min] (Step S2)
1). E (j) = Bp (j) × 97.6 + Bi (j) × 29.2−Ml (j) × 43.0 (7)

Then, the glow time dt (j) [minutes] at the position of the j-th window box 7 after ignition is calculated by equation (8) (step S22). dt (j) = dt (j−1) + DT × E (j) / ET (8)

Since there is a proportional relationship between the glowing time and the cumulative value of the calorific value of combustion, equation (9) is obtained, and from this, equation (8) can be derived. dt (j) = DT × {E (j) / ET} (9) where DT [minutes] is the red heat time at the bottom surface of the raw material layer, ET
[Kcal / min] is defined as a cumulative combustion heat value per unit time from ignition to firing point f.

Next, the red tropical length Dx (j) [m in the machine length direction at the position of the j-th wind box 7 after ignition
m] is changed to dt (j) and strand traveling speed v [mm /
Min] according to equation (10). Dx (j) = dt (j) × v (10) It is determined whether or not j is p or less (step S23),
If j is determined to be p or less, step S17
The following processing is repeated. On the other hand, when j is larger than p, the process ends.

FFD obtained by the above processing
(I) is plotted in a coordinate system in which the vertical axis represents the distance in the depth direction of the raw material layer and the horizontal axis represents the distance in the longitudinal direction of the raw material layer while changing i and j, thereby obtaining the estimation result of the coke ignition line. Is obtained, and Dx (j) is sequentially added in the horizontal axis direction from the estimation result of the coke ignition line, whereby
The estimation result of the solidification completion line is obtained.

With respect to two kinds of operating conditions where the mixing conditions of the raw material ores were constant, a comparison experiment was performed between the method of estimating the progress of the sintering reaction of the present invention and the direct measurement of the progress of the sintering reaction using a thermocouple. . The operating conditions are Condition 1 and Condition 2 shown in the following table.

[0039]

[Table 1]

FIG. 8 is a graph showing the experimental result under the condition 1, and FIG. 9 is a graph showing the experimental result under the condition 2.
8 and 9, the horizontal axis indicates the distance in the machine length direction, and the vertical axis indicates the depth of the raw material layer. The solid line shows the estimation result of the coke ignition line according to the present invention, and the dashed line shows the estimation result of the solidification complete line according to the present invention. The circles indicate the positions of the actually measured coke ignition lines, and the crosses indicate the positions of the actually measured solidification completion lines. As a result of the experiment, the estimation of the progress of the sintering reaction according to the present invention shows almost the same results as the measured results, which indicates that the present invention is extremely effective in estimating the progress of the sintering reaction.

As described above, the position and shape of the coke ignition line are estimated based on the fact that there is a proportional relationship between the distance from the surface of the raw material layer to the combustion position and the cumulative value of the exhaust gas flow rate. Regardless of the coke distribution inside, the position and shape of the coke ignition line can always be estimated with high accuracy. Further, the inventors have paid attention to the fact that there is a proportional relationship between the glowing time and the cumulative value of the calorific value of combustion, thereby making it possible to estimate the solidification completion line.

[0042]

According to the method for estimating the progress of the sintering reaction according to the present invention as described in detail above, only the temperature and flow rate of the exhaust gas are required to estimate the coke ignition line. The coke ignition line can be estimated with a simple process.

Since the progress of the sintering reaction is estimated based on the temperature of the exhaust gas in the conveying direction, the flow rate of the exhaust gas, and the components of the exhaust gas, the estimation result is not affected by the particle size segregation of the raw material and is always highly accurate. It is possible to obtain an accurate estimation result. Further, since the progress of the sintering reaction including the solidification completion line is estimated, the present invention has an excellent effect such that a more detailed estimation can be made as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of a sintering process in which a sintering reaction progress estimation method according to the present invention is performed.

FIG. 2 is a graph showing a temperature distribution of exhaust gas in a sintering machine length direction.

FIG. 3 is a graph showing a flow rate distribution of exhaust gas in a sintering machine length direction.

FIG. 4 is a graph showing transition of components of exhaust gas in the machine length direction of a sintering machine.

FIG. 5 is a flowchart showing a process for estimating the progress of a sintering reaction according to the present invention.

FIG. 6 is a flowchart showing a process of estimating the progress of a sintering reaction according to the present invention.

FIG. 7 is a flowchart showing a process of estimating the progress of a sintering reaction according to the present invention.

FIG. 8 is a graph showing an experimental result under condition 1.

FIG. 9 is a graph showing experimental results under condition 2.

FIG. 10 is a schematic cross-sectional view of a raw material layer showing the progress of a sintering reaction by a Dwyroid type sintering machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sintering machine 2 Pallet truck 3 Mining hopper 4 Ignition furnace 5a-5n Raw material tank 6 Mixer 7 Wind box 8 Main intake pipe 9 Exhaust heat recovery equipment 10 Dust collector 11 Intake fan 12 Exhaust 13 Exhaust gas analysis probe 14 Exhaust gas flow rate Total 15 Exhaust gas thermometer 16 Exhaust gas component recorder 17 Exhaust gas flow recorder 18 Exhaust gas temperature recorder 19 Computer 20 Raw material layer a Raw material band b Red tropical c Sinter ore belt d Coke ignition line e Solidification completion line f Firing Point g Coagulation completion point

Claims (2)

[Claims] While conveying the raw material layer, a raw material containing coke boil is ignited at a raw material ignition position on the surface of the raw material layer, and gas in the raw material layer is transferred from a lower side of the raw material layer on the downstream side of the raw material ignition position. In the method for estimating the progress of the sintering reaction in a Dwyroid type sintering machine in which the sintering reaction proceeds by suction, the exhaust gas temperature is measured at a plurality of places where the gas sucked from the raw material layer is exhausted to the outside of the sintering machine. And measuring the flow rate of the exhaust gas and estimating the position and shape of the coke ignition line in the raw material layer from the measured values. 2. Exhaust gas components are measured at a plurality of locations where the exhaust is performed, and the measured values and the estimated position and shape of the coke ignition line in the raw material layer are used in the solidification complete line in the raw material layer. The method for estimating the progress of a sintering reaction according to claim 1, wherein the position and the shape are estimated.