JP5853571B2 - Thermoelectric power generation apparatus and thermoelectric power generation method using the same - Google Patents

Description

  The present invention uses a waste heat generated from a slag casting apparatus having a divided metal mold that continuously receives molten slag, converts the thermal energy into electric energy, and recovers the same The present invention relates to the thermoelectric power generation method used.

Asphalt pavement is the mainstream in Japan. Compared with concrete pavement using cement, the construction speed is fast and curing is unnecessary, so that the traffic blocking time can be shortened particularly when repairing an existing road.
Asphalt concrete used for the surface layer of such asphalt pavement consists of aggregate and asphalt, and the ratio of aggregate accounts for over 90%. Moreover, since the aggregate uses plastic asphalt as a binder, it plays the role of maintaining the shape of the road against the load of the vehicle and preventing wear by the tires. For this reason, aggregates for asphalt and concrete are required to be stronger and harder and more resistant to wear than general construction concrete aggregates.

  Therefore, as the aggregate for asphalt / concrete, hard stone such as hard sandstone is usually used without using limestone having low wear resistance. However, since the production area of the aggregate made of hard stone is limited, it is necessary to transport the aggregate from a distance depending on the area where the road is constructed, and there is a problem of increasing the transportation cost.

The asphalt pavement outline stipulates steel slag that can be used as aggregate for asphalt / concrete, in particular, single-grain steelmaking slag (SS) and crusheran steelmaking slag (CSS) for heating asphalt mixing. All of these are applications that make use of the hardness of steelmaking slag, and the proportion of the total aggregate for asphalt and concrete is actually being used even though it is very small.
However, since the specific gravity of steelmaking slag is about 15 to 20% greater than that of natural aggregate, the weight of aggregate per construction volume increases. Therefore, there is a problem that the transportation cost is excessive. Furthermore, steelmaking slag has a problem that it contains metal.

On the other hand, among steel slag, slag discharged from the blast furnace (so-called blast furnace slag) is gradually cooled and solidified (so-called blast furnace slow-cooled slag), which is used for roadbed materials, etc., but asphalt and concrete bones It is not used as a material.
This is because the blast furnace slow cooling slag has low wear resistance and is not suitable as an aggregate for asphalt / concrete. By the way, the amount of wear loss indicating the wear resistance of aggregates used in general asphalt concrete is about 15%, but in blast furnace slow cooling slag, the amount of wear loss is as high as about 30%, which is inferior to limestone. ing. In addition, since the blast furnace chilled slag is porous, there is a problem that the water absorption is high and the fluidity of the fresh concrete is lowered, so that it is only partially used.

Here, as a method for improving and densifying the porous point, which is a weak point of the blast furnace slow cooling slag, a method called a thin layer multilayer method is known. In this method, for example, as described in detail in Non-Patent Document 1, molten slag is poured thinly into a smooth cooling yard having a gentle slope, and cooling is performed by natural cooling by air cooling. In this method, the molten slag is successively stacked in two layers and three layers, and after the pouring of the uppermost layer is completed, cooling is performed by air cooling or by spraying a very small amount of cooling water.
According to this method, at least the vicinity of the molten slag flowing is preheated by the molten slag that has flown earlier, so the slag temperature is high and the slag layer is thin, so that the generated gas is easily levitated and separated. It becomes dense slow-cooled slag and has quality suitable for raw materials for concrete coarse aggregates. Especially when the thickness of each layer is 60 mm or less, it satisfies the JIS coarse aggregate standard with an absolute dry specific gravity of 2.4 g / cm ³ or more. It is said that.

  Patent Document 1 discloses a method for casting a blast furnace slag solidified product having a low water absorption rate, 1.5% or less and high wear resistance. In addition, the amount of grinding loss is 20% or less, and a method for continuously and efficiently casting a dense blast furnace slag solidified suitable for asphalt concrete aggregate used for asphalt pavement, and preventing deformation of the mold, An apparatus for stably casting a dense blast furnace slag solidified material suitable for asphalt paving aggregate is also shown.

  Here, with increasing environmental problems in recent years, efforts to save resources in various manufacturing processes are being sought in various fields. One of them is to use the waste heat of the manufacturing process as described above by directly converting it into electric power using a thermoelectric power generation element using the so-called Seebeck effect.

JP 2003-221611 A

"Steel Research" No. 301, 1980, p.13355-13362

  However, although Patent Document 1 provides a slag casting apparatus that stably casts a dense blast furnace slag solidified material suitable for asphalt pavement aggregates, the use of slag sensible heat / latent heat is completely different. No consideration has been given.

  The present invention has been developed in view of the above-described present situation, and utilizes the temperature difference between the heat source temperature in the process and the ambient temperature around the process in order to recover the waste heat generated in the slag casting apparatus as described above. Then, it aims at providing the thermoelectric power generation apparatus provided with the thermoelectric power generation unit provided with the thermoelectric power generation unit which converts thermal energy into electric energy, and collects it.

That is, the gist configuration of the present invention is as follows.
1. A thermoelectric power generation unit comprising a thermoelectric power generation module that converts thermal energy into electric energy, an insulating material installed on at least a high temperature surface side of the thermoelectric power generation module, and a heat receiving plate that receives heat from a heat source, and the thermoelectric power generation unit Is incorporated into the bottom of the split metal mold of a slag casting apparatus having a split metal mold that continuously receives molten slag, and the thermoelectric power generation unit is further pressurized to the low temperature surface side of the thermoelectric power generation module. Adjusting means, wherein the pressure adjusting means changes the contact pressure between the thermoelectric power generation module and the heat receiving plate according to the temperature of the split metal mold, and the bottom of the thermoelectric power generation unit and the split metal mold A thermoelectric generator having a function of controlling a contact area with the thermoelectric generator.

2 . 2. The thermoelectric power generation apparatus according to 1, wherein the thermoelectric power generation unit includes means for cooling the thermoelectric power generation unit.

3 . Above the split metal mold, a thermoelectric power generation module that converts thermal energy into electrical energy, an insulating material installed on at least a high temperature surface side of the thermoelectric power generation module, and a heat receiving plate that receives heat from a heat source are provided. The thermoelectric generator according to 1 or 2 , wherein a thermoelectric generator unit is installed.

4 . A thermoelectric power generation method using the thermoelectric power generation device according to any one of 1 to 3 above to receive heat of a slag received by a divided metal mold and convert it into electric power.

  By using the thermoelectric generator of the present invention, a dense blast furnace slag solidified material suitable for asphalt / concrete aggregate used for asphalt pavement having a water absorption rate of 1.5% or less and a weight loss of 20% or less is continuously obtained. When producing efficiently, the waste heat generated when the slag solidifies can be used to generate power effectively, and asphalt / concrete aggregates can be produced while creating electrical energy.

It is sectional drawing of the thermoelectric power generation unit according to this invention. It is an arrangement figure showing an example of a slag casting device which casts a blast furnace slag solidified product provided with a thermoelectric generator of the present invention. It is a graph which shows the high temperature side temperature transition of the thermoelectric power generation unit at the time of changing mold thickness.

Hereinafter, the present invention will be specifically described with reference to the drawings.
In FIG. 1, 1 is a thermoelectric element, and 2 is an electrode, and these constitute a thermoelectric power generation module 3. 4 is an insulating material, and 5 is a pressure adjusting means. Reference numeral 6 denotes a heat conductive sheet, 7 denotes a protective plate, and 8 denotes a thermoelectric power generation unit. Furthermore, 9 is a heat receiving plate.
As shown in FIG. 1, the basic configuration of the thermoelectric power generation unit 8 of the present invention is a P-type and N-type thermoelectric element 1 having electrodes 2 on both sides, a ceramic insulating material 4 disposed on both sides, and And pressure adjusting means 5 provided outside the insulating material on the low temperature side. The pressure adjusting means 5 can be provided on the high temperature side or on both the low temperature side and the high temperature side.
Furthermore, by operating the pressure adjusting means 5, an appropriate pressing force can be applied to the high temperature surface side of the thermoelectric power generation unit, and a desired contact area with the heat source can be ensured.

  In order to produce coarse aggregate for concrete from blast furnace slow-cooled slag (hereinafter simply referred to as blast furnace slag), the amount of pores in the blast furnace slag must be reduced to be dense. Therefore, conventionally, when using a slag solidification / reversing device, when flowing the molten blast furnace slag onto the mold, the blast furnace slag is likely to foam in the presence of water, so water is not sprayed directly on the blast furnace slag. Devices for cooling and solidifying have been used.

  FIG. 2 shows an example of a slag casting apparatus (hereinafter simply referred to as a slag casting apparatus) for casting a blast furnace slag solidified product that can be used in the practice of the present invention. The slag casting apparatus used in the present invention is a continuous metal casting machine that is capable of continuously casting as shown in FIG. 2 after molten slag is poured from the slag pan into the slag bowl. A molten slag is received by a mold (hereinafter simply referred to as a split mold or a mold), and continuously formed into a solidified slag.

  By adjusting the depth of the above-mentioned split mold, a solidified slag solidified into a plate having a predetermined thickness can be produced. The solidified slag is peeled off when the mold is inverted at the end of the continuous casting machine of the slag casting apparatus, and dropped onto the ground or the like to be collected. Then, the divided mold from which the solidified slag has been peeled returns to the molten slag supply position in an inverted state, re-inverts, and receives the molten slag again.

  The temperature of the split mold is preferably measured by attaching radiation thermometers at two positions, a position where the mold surface temperature before casting can be measured and a position where the solidified slag surface temperature immediately before reversal can be measured.

  In order to reduce the porosity of blast furnace slag, it is most effective to increase the cooling / solidification rate of the blast furnace slag. In addition, since the blast furnace slag has a low thermal conductivity, the cooling rate is generally determined by the solidified thickness of the blast furnace slow-cooled slag. Therefore, the solidification thickness of the blast furnace slow cooling slag is one of important control factors.

  That is, it is preferable that the slag has a solidification thickness of 10 mm or more because the cooling rate at the center of the blast furnace slag is hardly affected by the cooling conditions such as water cooling to the surface, the thermal conductivity of the mold, and the specific heat. On the other hand, it is preferable that the slag has a solidification thickness of 30 mm or less because the generation of gas from the inside of the blast furnace slag and the generated bubbles can be suppressed extremely efficiently without being trapped in the blast furnace slag during solidification. Therefore, the solidification thickness of the slag is preferably in the range of about 10 to 30 mm.

In addition, water spraying on the surface of the slag during cooling of the blast furnace slag not only increases the water absorption rate by making the surface layer of the blast furnace slag porous, but also reduces the specific gravity and increases the amount of slippage. This is not preferable because H ₂ S gas is generated due to the reaction with, and adversely affects the surrounding environment.
The solidified blast furnace slag after peeling from the mold may be cooled as it is. This slag coagulum has a large sensible heat with a slag surface temperature of 800-1000 ° C and a slag center temperature of less than 1200 ° C, so even if sensible heat is recovered by steam recovery or chemical conversion by heat exchange good. Even after spraying, sprinkling water cooling does not change the density and water absorption rate of the solidified blast furnace slag, but as described above, H ₂ S gas is generated and the surrounding environment is deteriorated. It is desirable not to use it.

When the molten blast furnace slag is poured into the mold, and solidification and cooling are repeated many times, the base temperature of the mold rises. When the temperature of the mold itself becomes high in this way, not only the ability to cool the blast furnace slag decreases, but also the strength of the mold itself decreases, or the solidified product of the blast furnace slag and the mold are seized to peel off the solidified slag. Will not be possible.
Therefore, at present, in order to prevent an excessive temperature rise of the mold, it is necessary to indirectly cool the mold from the back surface or cool the mold when the slag is discharged.

  In order to solve the above heating problem, the present invention can be indirectly cooled from the back surface of the mold via the thermoelectric power generation unit. In that case, it is preferable that the thickness of the mold does not exceed the heat resistance temperature of the thermoelectric power generation element Bi-Te system to be used and the thickness is such that the maximum power generation amount can be obtained. For reference, FIG. 3 shows the temperature transition on the high temperature side of the thermoelectric element when the mold thickness is changed.

  In order to suppress the temperature rise of the mold itself and increase the productivity, it is preferable that the time for holding the high-temperature blast furnace slag on the mold is the shortest time. Therefore, it is necessary to manage the temperature at which the slag falls from the mold. Here, it is known that when the temperature of the blast furnace slag becomes 1200 ° C. or less, molten blast furnace slag does not come out from the solidified blast furnace slag. Therefore, if the inside of the blast furnace slag is cooled to 1200 ° C. or less, a completely solidified blast furnace slag solidified product can be obtained. At this time, the surface temperature of the blast furnace slag solidified product is about 800 to 1000 ° C. Therefore, in actual production equipment, it is difficult to actually measure the temperature inside the blast furnace slag solidified material, and therefore the surface temperature of the blast furnace slag solidified material may be managed as an index.

  The temperature at the bottom of the mold is set to 100 ° C. to 300 ° C. for efficient power generation by the thermoelectric power generation unit. In addition, in order to generate power more efficiently, thermoelectric power generation units (modules) with different operating temperature ranges are built into the split mold, and the pressure adjustment device built into the unit is used, depending on the temperature at the bottom of the mold. It is also possible to select a thermoelectric power generation unit to generate power, and to make contact with a pressing force.

Moreover, in this invention, a thermoelectric power generation unit can also be installed above a casting_mold | template. The thermoelectric power generation unit installed above this mold increases the area of the heat receiving plate attached to the thermoelectric power generation unit with respect to the area of the thermoelectric power generation unit so that thermoelectric power generation can be efficiently performed even when the slag surface temperature becomes low. In addition, a heat receiving plate with fins can be used. It is further preferable in the present invention to increase the area of the heat receiving plate using the finned heat receiving plate.
In addition, the thermoelectric power generation unit installed above the mold is installed along the inclination of the split mold, and the installation distance may be changed according to the slag surface temperature that decreases from the slag receiving to the discharge. it can.

In the present invention, as shown in FIG. 1, a protective plate 7 can be provided outside the insulating material 4 described above. The insulating material 4 and the protection plate 7 on the high temperature surface side can be the heat receiving plate 9.
The protective plate 7 (heat receiving plate 9) may be a metal plate, a ceramic plate, or a sheet-like or foil-like plate described later as long as it can be used in the environment where the thermoelectric power generation module of the present invention is used. However, an iron plate, a copper plate, etc. are suitable because they also have a high heat transfer capability (heat sink function).

  In the present invention, as shown in FIG. 1, a heat conductive sheet 6 is provided between the insulating material 4 and the protective plate 7 in order to further improve the thermoelectric power generation efficiency. Can do. These thermal conductive sheets 6 have a predetermined thermal conductivity, and are not particularly limited as long as they are sheets that can be used in the environment where the thermoelectric power generation module is used. Examples thereof include graphite sheets.

  In the thermoelectric power generation unit 8 of the present invention, it is preferable to provide the pressure adjusting means 5 on the insulating material side of the low temperature surface. The pressure adjusting means 5 changes the contact pressure between the thermoelectric power generation unit and the heat receiving plate in accordance with the temperature of the heat source, thereby securing a desired contact area with the heat source and obtaining an expected power generation amount. .

  The pressure adjusting means 5 is not particularly limited as long as it is a means capable of applying a predetermined pressure to the insulating material of the thermoelectric power generation unit, but using a spring-type block, a hydraulic piston, or the like can provide uniform pressure application. It is particularly suitable from the viewpoints of properties and stability. In addition, a highly heat conductive material that has elasticity and good heat conductivity can be used.

  It is preferable to control the pressing force against the high temperature surface of the module in the thermoelectric generator unit to 2 MPa or less. This is because if the pressure exceeds 2 MPa, the above-described module may be damaged. More preferably, it is 0.5-2 MPa.

  Furthermore, in the present invention, in order to further increase the power generation efficiency of the thermoelectric power generation module, it is preferable to separately provide a cooling means (cooling device) on the low temperature surface side of the thermoelectric power generation unit. Such cooling means is not particularly limited, but examples include a cooling device provided with cooling fins, a water cooling device utilizing contact heat transfer, a heat sink utilizing boiling heat transfer, and the like. The water cooling device, for example, once receives cooling water in a known water supply header, and connects the cooling water to a cooling water pipe provided in advance in a split mold using a coupler or the like. There are methods to supply.

The size of the thermoelectric power generation module according to the present invention is preferably 1 × 10 ⁻² m ² or less. This is because the deformation of the thermoelectric power generation module can be suppressed by setting the size of the module as described above. More preferably, it is 2.5 × 10 ⁻³ m ² or less.

In the present invention, a plurality of thermoelectric power generation units described above can be used simultaneously to arrange a thermoelectric power generation unit.
The size of the thermoelectric power generation unit is preferably 1 m ² or less. This is because, by setting the units as described above, deformation of the thermoelectric power generation modules and the thermoelectric power generation unit itself can be suppressed. More preferably, it is 2.5 × 10 ⁻¹ m ² or less.

  The thermoelectric power generation method using the thermoelectric power generation apparatus of the present invention will be described. After supplying molten slag to a plurality of continuous molds having a casting depth in the range of approximately 10 to 30 mm, the mold cooling and atmosphere In the process of continuously producing solidified blast furnace slag, which is discharged from the mold when the temperature of the free surface of the slag falls below about 1000 ° C, the slag is cooled by heat dissipation to about 1400 ° C to about 800 ° C. The heat dissipated from the slag in the range is recovered by a thermoelectric power generation unit incorporated in the split mold and, if necessary, a thermoelectric power generation unit installed above the split mold to generate electricity.

Hereinafter, the example which implemented this invention is demonstrated.
As the split mold, a cast steel mold having a length of 1 m, a width of 2 m, a depth of 20 mm, and a thickness of 8 mm was used.
Each module is the thermoelectric power generation unit 8 shown in FIG. 1, and the main specifications are as follows. That is, in the thermoelectric power generation unit, thermoelectric power generation modules (performance 10 kW / m ² , size 2.5 × 10 ⁻³ m ² (thickness: 5 mm × length: 50 mm × width: 50 mm)) were arranged in a grid pattern. The contact pressure between the heat receiving plate (iron plate) used as a protective plate and the module was controlled by the pressure adjusting device according to the temperature of the slag. Both units were equipped with a graphite sheet heat conduction sheet.

  In this example, first, molten blast furnace slag was received in a slag pan having a capacity of 40 tons and transferred to the continuous caster shown in FIG. Molten slag was discharged from this slag pan at an outflow rate of about 2 ton / min, and supplied onto the moving split mold through a slag tub. At this time, the moving speed of the split mold was about 17 m / min. The number of molds in this apparatus was 132, and the total length of the apparatus was about 65 m.

  When thermoelectric power generation was performed under the above conditions, a power generation amount of about 5 kW was obtained per mold, and 132 molds were obtained, resulting in 0.7 MW power generation. Therefore, it can be seen that the inventive example according to the present invention effectively creates electrical energy.

  Further, by holding for 230 seconds after receiving, the surface temperature of the solidified slag immediately before reversal became 1000 ° C. or less, and molten slag did not come out from the solidified slag that had been reversed, peeled off or dropped. That is, the slag center temperature was 1200 ° C. or less.

In addition, by optimizing the thickness of the cast steel mold, the amount of power generated by the thermoelectric generator was maximized.
Here, the thickness is such that the maximum power generation amount can be obtained without exceeding the heat resistance temperature of the thermoelectric power generation element Bi-Te system to be used. The inversion and reinversion time was minimized so that the maximum amount of power generation was obtained.

The invention examples according to the present invention are all dense blast furnace slag suitable for asphalt / concrete aggregates with high blast furnace slag quality, water absorption: 1.5% or less, grinding loss: 20% or less. It was confirmed that a coagulum was produced.
When it is desired to increase the flow rate of the molten slag, the metal mold can be enlarged, or the length of the continuous casting machine can be extended to increase the moving speed of the metal mold.

According to the present invention, the heat generated from the slag casting apparatus can be effectively converted into electric power, which contributes to energy saving in the manufacturing factory.
In the present invention, the heat of slag discharge is used, but other heat sources such as molten steel or hot metal can be used as a heat source, for example, in a casting machine.

DESCRIPTION OF SYMBOLS 1 Thermoelectric element 2 Electrode 3 Thermoelectric power generation module 4 Insulation material 5 Pressure adjusting means 6 Thermal conduction sheet 7 Protection plate 8 Thermoelectric power generation unit 9 Heat receiving plate

Claims (4)

A thermoelectric power generation unit comprising a thermoelectric power generation module that converts thermal energy into electric energy, an insulating material installed on at least a high temperature surface side of the thermoelectric power generation module, and a heat receiving plate that receives heat from a heat source, and the thermoelectric power generation unit Is incorporated into the bottom of the split metal mold of a slag casting apparatus having a split metal mold that continuously receives molten slag, and the thermoelectric power generation unit is further pressurized to the low temperature surface side of the thermoelectric power generation module. comprising adjusting means, pressure adjustment means, the split depending on the temperature of the metal mold, the bottom of changing the contact pressure between the thermoelectric power generation module and the heat receiving plate and the thermoelectric power generation unit wherein split metal mold A thermoelectric generator having a function of controlling a contact area with the thermoelectric generator.   The thermoelectric power generation apparatus according to claim 1, wherein the thermoelectric power generation unit includes means for cooling the thermoelectric power generation unit.   Above the split metal mold, a thermoelectric power generation module that converts thermal energy into electrical energy, an insulating material installed on at least a high temperature surface side of the thermoelectric power generation module, and a heat receiving plate that receives heat from a heat source are provided. The thermoelectric power generation apparatus according to claim 1, wherein a thermoelectric power generation unit is installed.   A thermoelectric power generation method using the thermoelectric power generation device according to any one of claims 1 to 3 to receive heat of slag received by a split metal mold and convert it into electric power.

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