JP5949575B2 - Heat recovery system and heat recovery method for solidified slag - Google Patents

Description

  The present invention relates to a solidified slag heat recovery system and a heat recovery method for recovering sensible heat of solidified slag formed by solidification molding of slag (mineral) discharged in a steel manufacturing process or the like.

  Slag discharged in the steel manufacturing process is used as granulated sand or slag aggregate through granulation or slow cooling. On the other hand, since the sensible heat of molten slag has a magnitude of about 0.5 GJ per ton of pig iron, a large energy saving effect can be expected if the sensible heat of molten slag can be recovered. For this reason, the technique of collect | recovering and utilizing the slag's sensible heat simultaneously with the use of slag is expected.

  As a method of recovering the slag heat of slag, Patent Document 1 discloses that a molten slag is solidified and formed into a relatively thick shape using a casting machine, and the solidified slag is inserted into a heat recovery device in a high temperature state. A method for recovering sensible heat is described. When the slag is solidified and formed into a thick wall, the surface area per unit volume of the slag is reduced, so that the solidified slag is easy to keep warm, the temperature drop of the solidified slag due to transportation etc. is suppressed, and it can be supplied to the heat recovery device at a high temperature. it can. Moreover, since it has thickness, it is easy to hold | maintain the center of the board thickness (solidification thickness) of solidification slag with high temperature, and it can supply to a heat recovery apparatus in the state which has high sensible heat.

JP-A-57-182086

  However, since the thermal conductivity of the slag is generally low, when the molten slag is solidified and molded into a relatively thick shape as in the method described in Patent Document 1, the surface of the slag is used in the heat recovery device due to the heat conduction rate control inside the slag. Is significantly lower than the internal temperature of the slag. As a result, the temperature of the gas that is the heat recovery medium is lowered. On the other hand, since the inside of the slag is difficult to cool, the slag cannot be sufficiently cooled by the heat recovery device, the temperature at the time of discharging the slag becomes high, and the heat recovery rate decreases.

  In order to solve such problems, it is conceivable to reduce the solidification thickness of the slag. However, when the solidified thickness of the slag is reduced, when a large number of flat plate-shaped solidified slags are charged and filled in the heat recovery device, a large number of laminated portions that are in close contact with each other are generated, making it difficult to remove heat. For this reason, the heat recovery rate cannot be increased only by reducing the solidification thickness of the slag. In addition, if the solidification thickness of the slag is too thin, the solidified slag that has been crushed after heat recovery has a shape defect, which deteriorates the yield of the recovered slag aggregate.

  The present invention has been made in view of the above, and provides a heat recovery system and a heat recovery method for a solidified slag capable of easily recovering sensible heat and slag aggregate having a good shape from the solidified slag. Objective.

  In order to solve the above-described problems and achieve the object, a solidified slag heat recovery system according to the present invention is formed by pouring molten slag obtained from a blast furnace into a continuously conveyed mold. And a heat recovery device that recovers sensible heat of the solidified slag that has been provided with uneven shapes by the caster. To do.

  Further, the solidified slag heat recovery system according to the present invention is characterized in that, in the above-mentioned invention, a concave and convex shape is imparted to the lower surface of the solidified slag by a convex raised portion provided at least one place on the bottom of the mold. And

  Further, the solidified slag heat recovery system according to the present invention is characterized in that, in the above invention, an uneven shape is imparted to the upper surface of the solidified slag by an operation of mechanically pushing a forming tool into the upper surface of the slag in the mold. And

  The solidified slag heat recovery system according to the present invention is characterized in that, in the above invention, the solidified slag is charged into the heat recovery device in a state where the surface temperature of the solidified slag is 300 ° C. or higher.

  Further, the heat recovery method for solidified slag according to the present invention has different uneven shapes with respect to the upper and lower surfaces of the solidified slag formed by pouring molten slag obtained from a blast furnace into a continuously conveyed mold. And a heat recovery step of recovering the sensible heat of the solidified slag to which the concavo-convex shape is provided by the shape applying step.

  According to the present invention, since the gas flow path can be secured when the solidified slag is thinned and the solidified slag is filled in the heat recovery device, the sensible heat can be easily recovered from the solidified slag. Moreover, the slag aggregate of a favorable shape can be recovered from the solidified slag crushed after heat recovery.

FIG. 1 is a diagram showing a schematic configuration of a heat recovery system according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a mold having one convex raised portion. FIG. 3 is a schematic view showing a state in which the solidified slag of the present embodiment is charged and filled in a heat recovery device. FIG. 4 is a schematic diagram showing a state in which a flat plate-shaped solidified slag is charged and filled in a heat recovery device. FIG. 5 is a schematic diagram showing the shape and arrangement of a forming tool for mechanically forming irregularities on the upper surface of the slag in the mold. FIG. 6 is a schematic diagram showing the shape and arrangement of a forming tool for mechanically forming irregularities on the upper surface of the slag in the mold. FIG. 7 is a diagram showing a simulation model for calculating the heat recovery rate. FIG. 8 is a diagram showing a simulation model for calculating the heat recovery rate. FIG. 9 is a diagram showing simulation conditions for calculating the heat recovery rate. FIG. 10 is a diagram illustrating a simulation result for calculating the heat recovery rate.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. Moreover, in description of drawing, the same code | symbol is attached | subjected and shown to the same part.

  First, a schematic configuration of a heat recovery system for solidified slag according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the heat recovery system 1 includes a casting machine 2 provided with a movable mold 21, a supply device 4 for supplying molten slag 3 from a blast furnace to the mold 21, and the mold 21 discharged from the mold 21. And a heat recovery device 6 for charging the solidified slag 5 and recovering the sensible heat of the slag.

  The mold 21 has at least one convex raised portion at the bottom. FIG. 2 is a schematic view showing a mold 21 having one convex raised portion. The convex raised portion a shown by being surrounded by a dotted line in FIG. 2 can impart a concave / convex shape (plate thickness difference) to the lower surface (bottom surface) of the solidified slag 5 to partially reduce the solidified thickness. In FIG. 2, a region having a height H of more than 3 mm from the minimum height position (the portion having no bulge) at the bottom of the mold 21 is defined as a convex bulge portion a.

The solidified slag 5 thus provided with the uneven shape is charged into the heat recovery device 6 and filled to recover the sensible heat of the solidified slag 5. The solidified slag 5 is charged at a surface temperature of 300 ° C. or higher. Thereby, for example, when recovering the sensible heat of the solidified slag 5 as steam, the recovery can be performed under a steam condition of 10 kg / cm ² low steam pressure (180 ° C. saturated steam) or more used in a factory.

  FIG. 3 is a schematic view showing a state in which the solidified slag 5 with the uneven shape is charged and charged in the heat recovery device 6. FIG. 4 is a schematic view showing a state in which a flat plate-shaped solidified slag is charged into the heat recovery device 6 and filled. As shown in FIG. 4, when the flat plate-shaped solidified slag is filled in the heat recovery device 6, a large number of portions b (shaded portions) that are in close contact with each other are generated, so a heat recovery gas flow path is secured. Difficult to collect sensible heat. On the other hand, when the heat recovery device 6 is filled with the solidified slag 5 to which the uneven shape is imparted, a gap is also generated in the laminated portion as shown in FIG. Recovery rate is improved.

  FIG. 2 schematically shows the particles B that can be collected from the solidified slag 5 formed by the mold 21. By partially reducing the solidification thickness in this way, when producing slag aggregate by performing crushing treatment and sieving from the solidified slag 5, coarse particles can be collected from the thickened portion, Fine particles can be collected from the thin part of.

  Further, in this mold 21, the width Y of the lower portion where the height H from the minimum height position (the portion without the bulge) of the bottom portion is 0 to 3 mm is equal to or less than the target value Tmax of the maximum solidification thickness of the solidification slag 5. As shown, the side wall D of the mold 21 (and the convex ridges a when there are a plurality of convex ridges a) are arranged close to each other. Therefore, according to the mold 21 shown in FIG. 2, since cooling is promoted in the periphery of the mold 21, by setting the position adjacent to the periphery of the mold 21 as the position for collecting the coarse particles B that are most difficult to solidify, The variation in solidification / cooling time due to the difference in solidification thickness is alleviated, and the slag aggregate material can be made uniform.

  Note that when the width Y of the lower portion of the mold 21 (the height H from the minimum height position is 0 to 3 mm position) is larger than the target value Tmax of the maximum solidification thickness of the solidified slag, the size of the collected coarse particles B is Since it becomes larger than the upper limit of the required particle size, secondary crushing is required, so that the coarse particle ratio after the secondary crushing cannot be controlled to a high level, and the crushing cost is also increased.

  According to the particle size distribution of the coarse aggregate 2005 defined by JIS_A5011-1, the required amount of coarse particles having a particle size of 20 to 25 mm is as small as 10 mass% or less, and the required amount of coarse particles having a particle size of 15 to 25 mm is 15 It is supposed to be about ~ 45 mass%. If the uneven shape of the mold 21 is designed so that the ratio of the solidified thickness portion and the thinned thickness portion of the solidified slag 5 formed by the mold 21 matches the required particle size distribution, the required amount Coarse and fine grains can be collected. As a result, a slag aggregate having an appropriate shape and particle size distribution can be produced from the solidified slag 5.

  The required amount of coarse particles having a particle diameter of 20 to 25 mm is as small as about 1/10 of the total number when converted to the number ratio, and the mass ratio is less than 50%. There is no particular problem even if the solidified thickness of 5 is reduced to reduce the portion where coarse particles can be collected.

  By the way, as described above, the mold 21 having the convex bulge at the bottom has a relatively gentle convex shape with a curved surface on the bottom surface of the solidified slag 5 in order to prevent the mold 21 from being damaged by thermal stress. It is desirable. Therefore, the mold 21 having a long contact time with the slag and a large heat load is formed to have a gentle convex shape, and only the plate thickness distribution is given to the lower surface of the solidified slag 5. On the other hand, the tip of the forming tool disposed on the forming roll 22 having a short contact time with the slag and a small thermal load is formed into an acute notch shape, and steep irregularities are given to the upper surface of the solidified slag 5.

  Therefore, the heat recovery system 1 according to the present embodiment includes a forming roll 22 that can be moved up and down according to the conveyance of the mold 21, and mechanically forms unevenness on the upper surface of the slag in the mold 21. As illustrated in FIGS. 5 and 6, which are cross-sectional views of a portion (pushing surface) in contact with the slag of the forming roll 22, the forming roll 22 of the present embodiment has a concavo-convex shape by mechanical pressing into the solidified slag 5. A plurality of convex forming tools 7 to be imparted are arranged in parallel, and a repetitive shape of mountains and valleys is provided. The width W of the forming tool 7 that gives the uneven shape to the upper surface of the solidified slag, and the width of the convex raised portion a at the bottom of the mold 21 that gives the uneven shape to the lower surface of the solidified slag (from the minimum height position of the bottom of the mold 21). The relationship between the height H and the width of the region where the height H exceeds 3 mm is C> W, the tip of the forming tool 7 has an acute notch shape, and the bottom of the mold 21 has a curved shape. Is preferred. The plurality of forming tools 7 arranged on the pushing surface may be arranged continuously as shown in FIG. 5, or may be arranged at intervals as illustrated in FIG. And the uneven | corrugated shape can be provided to the solidification slag 5 by these combined effects so that the slag aggregate of the particle size distribution required when the solidification slag 5 is crushed can be extract | collected.

The forming roll 22 of the present embodiment determines in advance the horizontal position of the mold 21 for collecting coarse grains and the horizontal position of the mold 21 for collecting fine grains from the shape of the convex ridges a of the mold 21. The unevenness is formed by the forming roll 22 so as to collect fine particles on the upper surface of the slag immediately above the convex ridge a. That is, the distance between the forming tools 7 (the distance between the crests of adjacent forming tools 7) X so as to reduce the interval between the uneven shapes provided by the forming roll 22 as the solidified thickness of the slag in the mold 21 decreases. (X ₁ , X ₂ , X ₃ ,...) Is reduced. Thereby, control of the particle size distribution from the coarse grain of the slag aggregate obtained from the solidification slag 5 to a fine grain can be performed from both upper and lower sides.

  According to such a mold 21 and the molding roll 22, the surface area of the solidified slag 5 is increased by providing the solidified slag 5 with an uneven shape, and it becomes easy to recover sensible heat from the solidified slag 5. Also, when the solidified slag 5 is stacked in the slag filling tank of the heat recovery apparatus 6, the gas easily flows through the filling tank, so that the heat recovery efficiency is greatly improved. Further, by providing uneven shapes having different shapes on the upper surface and the lower surface of the solidified slag 5, it is possible to directly build the shape and particle size distribution of the slag aggregate while suppressing the thermal load of the mold 21. Therefore, secondary crushing becomes unnecessary, and the slag aggregate can be obtained at a low cost without increasing the solidification thickness of the slag more than necessary.

  As described above, according to the heat recovery system 1 of the present embodiment, it is possible to secure a gas flow path even when the solidified slag 5 is filled in the heat recovery device 6 while reducing the solidified thickness of the slag. The sensible heat can be easily recovered from the solidified slag 5. In addition, since a slag aggregate having a good shape and particle size distribution can be obtained from the solidified slag after recovering sensible heat, the slag can be efficiently used.

  The mold 21 can be made of a metal or a structure having a multi-layered structure with heat resistance and heat insulation, such as inner surface castable construction. Moreover, the shaping | molding means which provides uneven | corrugated shape to the upper surface of a slag is not restricted to the shaping | molding roll 22, For example, the shaping | molding tool etc. of the processing system which raises / lowers up and down to a press shape, and the method of pressing-molding with dead weight may be sufficient. In that case, the uneven shape of the forming means is arranged so that the interval X of the uneven shape becomes smaller as the solidified thickness of the slag in the mold 21 becomes thinner.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these, and various modifications according to the specifications and the like are within the scope of the present invention. It is obvious from the above description that various other embodiments are possible within the scope of the above.

(Example)
As an example of the present invention, the following calculation was performed. First, as a case in which concavo-convex forming is not performed, a solidified slag A0 having a solidified thickness of 25 mm, a width of 150 mm, and a length of 150 mm is inserted into a heat recovery device to recover sensible heat, and the temperature and heat of the heat recovery gas A simulation for calculating the recovery rate was performed. In the simulation, the solidified slag A0 was charged into a heat recovery device at 1000 ° C. and stacked at a height of 5 m, and the air (gas) at 25 ° C. was 100,000 while repeatedly charging and discharging the slag at a pitch of 1 t / min. It was assumed that heat exchange was performed by blowing Nm ³ / h in a countercurrent manner.

  Next, the case where unevenness molding was performed is shown. The uneven shape imparted to the solidified slag A0 is only a two-dimensional uneven shape for simplification of the model. Assuming coarse aggregate 2005 (particle size range 20 mm to 5 mm) as the particle size distribution of the slag aggregate, solidified slag A1 having an uneven shape on the upper surface and solidified slag A2 having an uneven shape on the lower surface, respectively. Calculated. The solidification thickness that is the basis of this calculation is 20 mm, which is the maximum value of the aggregate particle size range, because the secondary crushing is not required when unevenness is given, and is thinner than the case where the above unevenness forming is not performed. .

  FIG. 7 is a diagram illustrating a simulation model of the solidified slag A1 having an uneven shape on the upper surface. On the upper surface of this model, as shown in FIG. 7, seven 10 mm regular triangular notches are provided. Thus, the heat recovery rate of the solidified slag having an uneven shape on the upper surface (the average solidified thickness is 14.5 mm) A1 is the same as the solidified slag having the uneven shape in order to simplify the calculation. It is assumed to be equivalent to a flat solid slag A1 ′ having a solidification thickness of 14.5 mm.

  FIG. 8 is a diagram showing a simulation model of the solidified slag A2 having an uneven shape on the lower surface. As shown in FIG. 8, a gentle trapezoidal mold shape having a height of 7 mm is given to the lower surface of this model. In this way, the heat recovery rate of the solidified slag (solidified thickness average 16 mm) A2 having a concave and convex shape on the lower surface is not considered in order to simplify the calculation. It is assumed that it is equivalent to a flat solidified slag A2 ′.

  A simulation for calculating the heat recovery rate was performed for the three solidified slags. FIG. 9 shows the simulation conditions. FIG. 10 shows the simulation results. As shown in FIG. 10, the solidified slag A1 ′ (Case 2) having a concavo-convex shape on the upper surface and the solidified slag A2 ′ (Case 3) having a concavo-convex shape on the lower surface are the solidified slag A0 before the concavo-convex shape is imparted. The temperature of the gas from which sensible heat has been recovered (heat recovery gas temperature) is higher than (Case 1), and the heat recovery rate is also reduced by sufficiently reducing the temperature of the solidified slag after heat recovery (slag discharge temperature). It has improved.

  In addition, FIG. 10 converts the model (A1, A2) which gave the uneven | corrugated shape to solidification slag as above-mentioned, and converted into the flat plate-shaped model (A1 ', A2') which reduced the solidification thickness uniformly. The heat recovery rate is calculated. However, actually, when the solidified slag having the irregular shape is filled in the heat recovery device 6, the effect of being able to secure the gas flow path is also obtained. Therefore, from the result shown in FIG. 10, the heat recovery gas temperature further increases, and the heat recovery rate is improved.

DESCRIPTION OF SYMBOLS 1 Heat recovery system 2 Casting machine 21 Mold 22 Molding roll 3 Molten slag 4 Supply apparatus 5 Solidification slag 6 Heat recovery apparatus 7 Molding tool

Claims (5)

A casting machine that gives different uneven shapes to the upper and lower surfaces of the solidified slag formed by pouring molten slag obtained from a blast furnace into a continuously conveyed mold,
E Bei and a heat recovery apparatus for recovering the sensible heat of the coagulation slag granted different concave-convex shape in the lower surface and the upper surface Ri by the cool machine,
At the bottom of the mold, a convex ridge having a curved shape is provided,
The concavo-convex shape imparted to the lower surface of the solidified slag by the convex raised portion is a gentler concave shape than the concavo-convex shape of the upper surface of the solidified slag.
Heat recovery system of the coagulation slag characterized by and this. The convex ridges heat recovery system of the coagulation slag according to claim 1, wherein the this are found provided at least one or more places at the bottom of the mold. By mechanically pushing operation the forming tool against the slug top surface of the inner mold, Grant irregularities on the upper surface of the solidified slag,
The convex ridge has a gentle convex shape than the forming tool.
Heat recovery system of the coagulation slag according to claim 1 or claim 2, characterized in that.   The solidified slag heat recovery system according to any one of claims 1 to 3, wherein the solidified slag is charged into the heat recovery device in a state where the surface temperature of the solidified slag is 300 ° C or higher. . A shape imparting step for imparting different uneven shapes to the upper surface and the lower surface of the solidified slag formed by pouring molten slag obtained from a blast furnace into a continuously conveyed mold,
Anda heat recovery step for recovering the sensible heat of the coagulation slag Ri granted different concave-convex shape at the upper surface and the lower surface by the said shaping step,
The shape imparting step includes a step of imparting a concavo-convex shape to the lower surface of the solidified slag by a convex ridge having a curved shape provided at the bottom of the mold,
The concavo-convex shape imparted to the lower surface of the solidified slag by the shape imparting step is a gentler concave shape than the concavo-convex shape of the upper surface of the solidified slag.
Heat recovery method of solidifying slag characterized by and this.

Images