Patent Application
20150225804
The present invention relates to a pulverized-coal injection device, a blast furnace facility provided with the same, and a pulverized-coal supplying method.
Pulverized-coal injection (PCI; Pulverized Coal Injection) employed to supply a supplemental fuel for a blast furnace facility is a low-cost supplemental-fuel supplying method that is an alternative to heavy-oil injection that had been employed until the 1970s. Important requirements for pulverized coal (PCI coal) used for blast furnace injection include low moisture content, low volatile matter content, excellent combustibility, a combustion speed as fast as that of heavy oil, low combustion residues such as uncombusted carbon, ash, or the like, a heat of combustion equal to or greater than 6500 kcal/kg, low sulfur and phosphorus contents, and so forth.
In order to meet these requirements, as described in Patent Literature 1, relatively high-quality, expensive raw coal, such as bituminous coal or the like, is currently used as a raw material for PCI coal. Such raw coal is pulverized into a predetermined grain size by using a pulverizer, thus being turned into pulverized coal, and is transported to and stored in a storage tank installed in the vicinity of a blast-furnace main unit by means of gas-flow transportation that uses high-pressure air, nitrogen, or the like. Then, the pulverized coal is injected into the blast-furnace main unit, to be combusted therein, from a tuyere provided at a lower portion of the blast-furnace main unit together with hot air consisting of heated high-pressure air.
However, as described above, because high-quality, expensive raw coal is necessary as the raw material for PCI coal to be injected into the interior of the blast-furnace main unit as a supplemental fuel, the operating cost of the blast furnace facility is increased, and, as a result, the manufacturing cost of pig iron is increased.
In addition, although pulverized coal is injected into the blast furnace together with compressed air, the compressed air must be preheated to about 1200° C. by means of a burner or the like so that the furnace interior is not cooled by the compressed air at the time of this injection. A large amount of fuel, such as heavy oil or the like, is required to achieve this, and this has also caused an increase in the operating cost of the blast furnace facility.
The present invention has been conceived in light of the above-described circumstances, and an object thereof is to provide a pulverized-coal injection device with which the manufacturing cost of pig iron can be reduced by reducing the operating cost of a blast furnace facility, to provide a blast furnace facility provided with this pulverized-coal injection device, and to provide a pulverized-coal supplying method.
In order to solve the above-described problems, the present invention employs the following solutions.
Specifically, a pulverized-coal injection device according to a first aspect of the present invention is a pulverized-coal injection device configured so as to inject pulverized coal from a tuyere of a blast-furnace main unit together with heated, compressed injection air, wherein upgraded coal that has a self-heating property and that is upgraded from low-grade coal is used as a raw material for the pulverized coal.
With this pulverized-coal injection device, because the upgraded coal that is considerably more inexpensive than generally used raw coal such as bituminous coal or the like is used as the raw material of the pulverized coal to be injected into the interior of the blast-furnace main unit as the supplemental fuel, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility by reducing the cost of the supplemental fuel.
In addition, it is possible to contribute to energy saving by effectively utilizing the heat of the upgraded coal at other sites requiring heat.
In the pulverized-coal injection device according to the first aspect of the present invention, it is preferable that the above-described configuration include a heat transporting unit for transporting heat due to a self-heating effect of the upgraded coal to a site requiring heat.
In the case in which the above-described configuration is employed, because the heat due to the self-heating effect of the upgraded coal is transported to sites requiring heat by means of the heat transporting unit, fuel, power, or the like consumed to generate heat at these sites can be reduced; by doing so, the operating cost of the blast furnace facility can be reduced, and, consequently, the manufacturing cost of pig iron can be reduced.
In addition, because the upgraded coal is cooled by transporting the heat of the upgraded coal by means of the heat transporting unit, it is possible to prevent spontaneous combustion of the upgraded coal.
In the pulverized-coal injection device according to the first aspect of the present invention, it is preferable that, in the above-described configuration, the heat transporting unit be configured so as to subject the injection air, before being compressed, to heat exchange with the upgraded coal.
With the above-described configuration, the injection air is appropriately heated by undergoing heat exchange with the upgraded coal before being heated by a special heating means. Because of this, it is possible to reduce the energy used for further heating the injection air. In particular, because cold injection air, before being compressed, is subjected to heat exchange with the upgraded coal, it is possible to increase the cooling effect on the upgraded coal, to also increase the generation rate of the heat of compression of the injection air, and, accordingly, to reduce the energy required to heat the injection air.
In the pulverized-coal injection device according to the first aspect of the present invention, it is preferable that, in the above-described configuration, the heat transporting unit be configured so as to transport the heat of the upgraded coal to an upgrading device that upgrades the low-grade coal.
With the above-described configuration, because a portion of heat required at the upgrading device that upgrades low-grade coal is provided by the heat of the upgraded coal, it is possible to reduce the energy consumed at the upgrading device.
In the pulverized-coal injection device according to the first aspect of the present invention, it is preferable that the above-described configuration include a deactivating unit for deactivating the upgraded coal such that a predetermined level of the self-heating effect thereof is retained.
With the above-described configuration, because the self-heating effect of the upgraded coal is reduced, the need to transport the upgraded coal in a nitrogen atmosphere so as to prevent spontaneous combustion thereof is reduced, and the utilization rate of the nitrogen supplying device can be reduced. Because of this, the operating cost of the blast furnace facility can be reduced, and, consequently, the manufacturing cost of pig iron can be reduced.
In the pulverized-coal injection device according to the first aspect of the present invention, it is preferable that the above-described configuration include a mixing portion for mixing pulverized coal constituted of the upgraded coal and pulverized coal constituted of generally used raw coal, wherein the pulverized coal constituted of the raw coal is dried at the mixing portion and a downstream side thereof by using the self-heating effect of the upgraded coal.
In the case in which the above-described configuration is employed, the pulverized coal constituted of the raw coal is dried by the heat of the upgraded coal having a self-heating property when the pulverized coal constituted of the raw coal having greater moisture content than the upgraded coal is mixed with the pulverized coal constituted of the upgraded coal. Because of this, it is possible to partially omit or simplify the step of drying the raw coal. By doing so, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility by reducing equipment, energy, personnel, or the like involved in the drying step.
A blast furnace facility according to a second aspect of the present invention is provided with a pulverized-coal injection device having any one of above-described configurations.
With this blast furnace facility, because inexpensive upgraded coal is used as the pulverized coal to be injected into the interior of the blast-furnace main unit as the supplemental fuel, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility by reducing the cost of the supplemental fuel, and, also, the heat generated when the upgraded coal exhibits self heating can effectively be utilized.
In addition, a pulverized-coal supplying method according to a third aspect of the present invention is a pulverized-coal supplying method for injecting pulverized coal from a tuyere of a blast-furnace main unit together with heated, compressed injection air, the pulverized-coal supplying method including using upgraded coal upgraded from low-grade coal as a raw material for the pulverized coal, and transporting heat due to a self-heating effect of the upgraded coal to a site requiring heat and utilizing the heat thereat.
With this pulverized-coal supplying method, because the pulverized coal to be injected into the interior of the blast-furnace main unit as the supplemental fuel is inexpensive upgraded coal, the manufacturing cost of pig iron can be reduced by reducing the cost of the supplemental fuel. Moreover, by transporting the heat due to the self-heating effect of the upgraded coal to sites requiring heat, thus effectively utilizing the heat, the operating cost of the blast furnace facility can be reduced by reducing fuel, power, or the like consumed to generate heat at these sites, and, consequently, the manufacturing cost of pig iron can be reduced.
In addition, in the pulverized-coal supplying method according to the third aspect of the present invention, it is preferable that the above-described method include deactivating the upgraded coal such that a predetermined level of the self-heating effect thereof is retained.
With the above-described method, because the self-heating effect of the upgraded coal is reduced, the need to transport the upgraded coal in a nitrogen atmosphere so as to prevent spontaneous combustion thereof is reduced, and the utilization rate of the nitrogen supplying device can be reduced. Because of this, the operating cost of the blast furnace facility can be reduced, and, consequently, the manufacturing cost of pig iron can be reduced.
A pulverized-coal supplying method according to a fourth aspect of the present invention is a pulverized-coal supplying method for injecting pulverized coal from a tuyere of a blast-furnace main unit together with heated, compressed injection air, the pulverized-coal supplying method including mixing pulverized coal constituted of upgraded coal upgraded from low-grade coal and pulverized coal constituted of generally used raw coal, and drying the pulverized coal constituted of the raw coal by means of a self-heating effect of the upgraded coal.
With the above-described pulverized-coal supplying method, because the pulverized coal constituted of the raw coal is dried by the heat of the upgraded coal having a self-heating property when the pulverized coal constituted of the raw coal having a greater moisture content than the upgraded coal is mixed with the pulverized coal constituted of the upgraded coal, it is possible to partially omit or simplify the step of drying the raw coal. By doing so, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility by reducing equipment, energy, personnel, or the like involved in the drying step.
As described above, with a pulverized-coal injection device, a blast furnace facility provided with the same, and a pulverized-coal supplying method according to the present invention, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility.
A plurality of embodiments of the present invention will be described below based on
The blast-furnace main unit 2 has a general structure in which a furnace top hopper 7 is provided at a top portion, and a tuyere 8 and a tap hole 9 are provided at a lower portion. A blowpipe 11 is connected to the tuyere 8, and an injection lance 12 is connected to this blowpipe 11 so as to join therewith at an angle.
The charging conveyor 4 is installed so as to rise from the vicinity of a base portion of the blast-furnace main unit 2 to the furnace top hopper 7, a transport-direction downstream end (top end portion) of this charging conveyor 4 is positioned directly above the furnace top hopper 7, and the fixed-quantity raw-material supplying device 3 is installed at a portion directly above a transport-direction upstream end (bottom end portion) thereof.
The fixed-quantity raw-material supplying device 3 supplies raw materials, such as iron ore, which is the main raw material of pig iron 14, to be smelted in the blast-furnace main unit 2, coke that serves as fuel and a reducing agent, and limestone that serves as a scavenger, to the charging conveyor 4 at a constant supplying speed; these raw materials are charged into the blast-furnace main unit 2 from the furnace top hopper 7 by means of the charging conveyor 4; and the smelted pig iron 14 is accumulated at a bottom portion of the blast-furnace main unit 2. The smelted pig iron 14 is removed from the tap hole 9.
On the other hand, the pulverized-coal injection device 5A injects pulverized coal (PCI coal), which is a supplemental fuel, from the tuyere 8 (blowpipe 11) of the blast-furnace main unit 2 together with the injection air, which has been heated and compressed to form hot air, so as to increase the temperature in the blast-furnace main unit 2. This pulverized-coal injection device 5A is provided with a upgrading device 16, a charging line 17, a nitrogen-gas feeding device 18, a cyclone separator 19, a storage tank 21, a pulverized-coal supplying pipe 22, an injection-air feeding device 23, and so forth.
The upgrading device 16 and the cyclone separator 19 are connected by the charging line 17, and the nitrogen-gas feeding device 18 is connected at an upstream portion of the charging line 17. In addition, the storage tank 21 and the injection lance 12 are connected by the pulverized-coal supplying pipe 22. Furthermore, the injection air in the form of hot air generated at the injection-air feeding device 23 is supplied to the blowpipe 11.
Because the upgrading device 16 has a known configuration, a detailed description thereof will be omitted; however, in outline, it is a device that upgrades the properties of low-grade coal, such as inexpensive subbituminous coal, brown coal, or the like, into properties suitable as a supplemental fuel for the blast-furnace main unit 2 and, also, that generates supplemental-fuel pulverized coal (PCI coal) by pulverizing the upgraded coal. At this upgrading device 16, low-grade coal input from a receiving hopper 24 is cooled after the low-grade coal is subjected multiple times to drying and heating processing to remove moisture and volatile components therein, and is pulverized by a mill into the supplemental-fuel pulverized coal.
The injection-air feeding device 23 is a device that compresses the air taken in from an air intake pipe 25 by means of a compressor (not shown), that also heats this air to about 1200° C. by means of a heater or a burner (not shown), and that generates high-temperature, high-pressure, dry injection air for pulverized coal injection.
An intermediate portion of the air intake pipe 25 is molded into, for example, a spiral shape that goes around multiple times in the area surrounding the pulverized-coal supplying pipe 22, and this spiral portion serves as a heat exchanger 25a. This heat exchanger 25a serves as a heat transporting unit for transporting the heat due to the self-heating effect of the upgraded coal that passes through the interior of the pulverized-coal supplying pipe 22 to a site requiring heat, in this embodiment, for example, the injection-air feeding device 23.
With the pulverized-coal injection device 5A configured as described above, the pulverized coal constituted of the upgraded coal upgraded by the upgrading device 16 from low-grade coal is sent to the charging line 17, is mixed with nitrogen gas fed by the nitrogen-gas feeding device 18, forms a solid-gas two-phase flow, and is fed to the cyclone separator 19 in an inert atmosphere of nitrogen gas. The cyclone separator 19 is a type of centrifugal separator that separates and deaerates nitrogen gas from the pulverized coal by means of a centrifugal force, and the nitrogen gas is released to the exterior or collected. Subsequently, the pulverized coal is accumulated in the storage tank 21, and a required amount thereof is supplied to the injection lance 12 from the pulverized-coal supplying pipe 22.
On the other hand, with the air (external air) that is taken in from the air intake pipe 25 and supplied to the injection-air feeding device 23, the temperature thereof is increased when passing through the heat exchanger 25a, which is formed in an intermediate portion of the air intake pipe 25, by undergoing heat exchange with the heat due to the self-heating effect of the pulverized coal constituted of the upgraded coal that precipitates in the interior of the pulverized-coal supplying pipe 22 at a relatively low speed, and, while possessing this heat, the air is supplied to the injection-air feeding device 23, where the air is further compressed and heated into high-temperature, high-pressure hot air of about 1200° C. In other words, the injection air undergoes heat exchange with the upgraded coal before being compressed and heated at the injection-air feeding device 23.
Then, the pulverized coal (upgraded coal) supplied to the injection lance 12 is mixed with the injection air supplied to the blowpipe 11, the pulverized coal is ignited and combusted by coming into contact with the high-temperature injection air in the form of hot air and forms flames at the tip of the blowpipe 11 which, in turn, form a raceway, and thus, coke charged into the blast-furnace main unit 2 is combusted. By doing so, iron ore charged together with the coke forms pig iron (molten iron) 14 by undergoing reduction and is removed from the tap hole 9.
With the pulverized-coal injection device 5A configured as described above, pulverized coal constituted of upgraded coal that has a self-heating property and that is upgraded from low-grade coal is used as the pulverized coal to be injected from the tuyere 8 of the blast-furnace main unit 2 together with the heated and compressed injection air. Because the cost of the upgraded coal is considerably lower than generally used raw coal, such as bituminous coal or the like, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility 1A by reducing the cost of the supplemental fuel. In addition, it is possible to contribute to energy saving by effectively utilizing the heat of the upgraded coal at other sites requiring heat.
In addition, in this embodiment, as an example of the heat transporting unit for transporting the heat due to the self-heating effect of the pulverized coal generated from the upgraded coal to other sites requiring heat, the heat exchanger 25a is provided in the intermediate portion of the air intake pipe 25 through the air to be taken into the injection-air feeding device 23 passes, and this air that passes through the interior thereof undergoes heat exchange with the pulverized coal that passes through the interior of the pulverized-coal supplying pipe 22. Therefore, the injection air is appropriately heated by undergoing heat exchange with the pulverized coal before being injected.
Because of this, it is possible to contribute to reducing the manufacturing cost of pig iron by reducing the operating cost of the blast furnace facility 1A by achieving a considerable saving in terms of energy such as fuel, power, or the like to be consumed for further heating the injection air at the injection-air feeding device 23. In addition, because the upgraded coal is cooled by transporting the heat of the upgraded coal that passes through the interior of the pulverized-coal supplying pipe 22 by means of the heat exchanger 25a, it is possible to prevent spontaneous combustion of the upgraded coal.
In particular, because cold injection air is subjected to heat exchange with the upgraded coal before being compressed at the injection-air feeding device 23, it is possible to increase the cooling effect on the upgraded coal at the pulverized-coal supplying pipe 22, to also increase the generation rate of the heat of compression of the injection air, and thus, to reduce the energy for heating the injection air.
The pulverized-coal injection device 5B differs from the pulverized-coal injection device 5A of the first embodiment (
The heating medium that flows through the interiors of the heat transporting pipe 32 and the heat exchanger 32a transports the heat due to the self-heating effect of the updated coal that passes through the interior of the pulverized-coal supplying pipe 22 to the updating device 16. At the updating device 16, this heat is used, for example, in a step of drying the low-grade coal. By doing so, it is possible to reduce the energy consumed to dry the low-grade coal.
The pulverized-coal injection device 5C differs from the pulverized-coal injection device 5A of the first embodiment (
At the deactivation device 42, the updated coal updated from low-grade coal by the updating device 16 is deactivated such that a predetermined level of the self-heating effect thereof is retained. As a specific deactivating method, coal that is cooled after being subjected to dry distillation at 300° C. to 500° C. at the updating device 16 is exposed to a processing-gas atmosphere containing oxygen at the deactivation device 42, and thus, processing of oxygen adsorbing (permeating) to the surface and the interior thereof is performed. By adjusting the adsorption level of oxygen, it is possible to adjust the level of the self-heating effect of the updated coal.
In this embodiment, the level of processing at the deactivation device 42 is set such that the updated coal that is sent out to the charging line 17 after completing the deactivating processing at the deactivation device 42 retains a certain level of self-heating effect.
Because the self-heating effect of the updated coal can be reduced by providing such a deactivation device 42, it is possible to eliminate the need to transport the updated coal in a nitrogen atmosphere so as to prevent spontaneous combustion thereof or to reduce the amount of nitrogen gas used. Therefore, the rate of operation of the nitrogen-gas feeding device 18 can be reduced, the operating cost of the blast furnace facility 1C can be reduced, and, consequently, the manufacturing cost of pig iron can be reduced.
The pulverized-coal injection device 5D differs from the pulverized-coal injection device 5A of the first embodiment (
The pulverized-coal injection device 5D is provided with two cyclone separators 19A and 19B, a mixing pipe 52 (mixing portion) is provided at a downstream portion thereof, and this mixing pipe 52 is connected to the storage tank 21. Because the configurations of other portions are the same as those in the pulverized-coal injection device 5A, the same reference signs are assigned to the respective portions and descriptions thereof will be omitted.
In this pulverized-coal injection device 5D, the pulverized coal constituted of the updated coal updated at the updating device 16 is supplied to the cyclone separator 19A from the charging line 17. In addition, the pulverized coal constituted of the raw coal is supplied to the cyclone separator 19B from a supplying device (not shown). Then, the two types of pulverized coal are mixed in the mixing pipe 52 and are accumulated in the storage tank 21. Subsequently, the two types of pulverized coal in the mixed state are supplied to the blast-furnace main unit 2 via the pulverized-coal supplying pipe 22 together with the injection air in the form of hot air that is supplied from the injection-air feeding device 23.
In the above-described configuration, because the pulverized coal constituted of the updated coal and the pulverized coal constituted of the raw coal are mixed in the mixing pipe 52, the moisture contained in the pulverized coal constituted of the raw coal is dried by the self-heating effect of the pulverized coal constituted of the updated coal at the interiors of the mixing pipe 52, the storage tank 21 at the downstream side thereof, and the pulverized-coal supplying pipe 22.
Because of this, it is possible to partially omit or simplify a step of drying the pulverized coal constituted of the raw coal or the raw coal itself. By doing so, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility 1D by reducing equipment, energy, personnel, or the like involved in the step of drying the raw coal.
This pulverized-coal injection device 5E is the pulverized-coal injection device 5D of the fourth embodiment (
Because the upgraded coal loses its self-heating property when completely deactivated, the deactivation device 42 does not completely deactivate the upgraded coal, and the moisture contained in the pulverized coal constituted of the raw coal is dried by self heating of the pulverized coal constituted of the upgraded coal while the pulverized coal constituted of the upgraded coal and the pulverized coal constituted of the raw coal are supplied to the blast-furnace main unit 2 from the mixing pipe 52 by passing through the pulverized-coal supplying pipe 22.
With this pulverized-coal injection device 5E, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility 1E by reducing equipment, energy, personnel, or the like involved in the step of drying the raw coal by partially omitting or simplifying the step of drying the raw coal.
In addition, because the self-heating effect of the upgraded coal can be reduced by using the deactivation device 42, it is possible to eliminate the need to transport the upgraded coal in a nitrogen atmosphere so as to prevent spontaneous combustion thereof or to reduce the amount of nitrogen gas used. Therefore, the rate of operation of the nitrogen-gas feeding device 18 can be reduced, the operating cost of the blast furnace facility 1E can also be reduced in this respect, and, consequently, it is possible to contribute to reducing the manufacturing cost of pig iron.
As has been described above, with the pulverized-coal injection devices 5A to 5E and the pulverized-coal injection method according to the individual embodiments described above, the manufacturing cost of pig iron can be reduced by reducing the operating cost of the blast furnace facility 1A to 1E.
The present invention is not limited only to the configurations of the individual embodiments described above; appropriate modifications and improvements can be incorporated within a range that does not depart from the scope of the present invention, and embodiments in which such modifications and improvements are incorporated are also encompassed in the range claimed by the present invention.
For example, the destination to which heat due to the self-heating property of upgraded coal is transported need not necessarily be the interior of the blast furnace facility, and the heat may be transported to an adjacent plant or other equipment. In addition, it is permissible to appropriately combine the configurations of the individual embodiments or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-207274 | Sep 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/074404 | 9/10/2013 | WO | 00 |
