JP2008201622A - Method and system for fuelization of metal powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To safely and maximally reuse metal waste without causing generation of new waste and deterioration of equipment. <P>SOLUTION: A combustion gas G drawn from an exhaust gas flow passage from an outlet duct of a calcination furnace 13 to an outlet duct of a preheater 12 is cooled, then the cooled combustion gas G is used to transfer a metal powder to a mixer 4, and after mixing the metal powder with a main raw material, the resulting mixture is blown into a cement kiln 10 as a fuel for firing cement and burned in the cement kiln 10. Since metal oxides are taken in cement after combustion, the metal waste can be reused without causing the generation of new waste, and the deterioration of equipment can be prevented even if high-temperature metal particles are fused and adhere to the inner wall of the cement kiln 10. Since the combustion gas G drawn from the exhaust gas flow passage is used as a gas for transferring the metal powder after being cooled, the risk of dust explosion can be reduced. It is possible to simultaneously carry out cooling of the combustion gas G and drying of water-containing waste W by introducing the combustion gas G into a drying machine 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and system for fuelizing metal powder, and more particularly to a method and system for effectively reusing metal waste as fuel.

  Conventionally, metals are frequently used in machine products, home appliances, and the like, and if they are discarded, metal waste is generated. Also, during the manufacturing process, processing waste during metal processing becomes waste. When a metal member is processed or polished, or when the metal is condensed from the air or deposited in the liquid, a metal waste may be obtained in a powder state having a large specific surface area. Among metal wastes, those with high purity are collected and reused as metal resources, but various impurities are often mixed in the wastes, and these are treated by landfill treatment etc. The However, the processing limit amount is tight, and the establishment of a circulation system is strongly desired nowadays when the amount of waste generation is expected to increase further.

  Therefore, for example, in Patent Document 1, aluminum dross and aluminum ash as daily and industrial wastes are used as main raw materials, and one selected from calcareous raw materials, silicate raw materials, sulfate raw materials, and iron raw materials. Or the manufacturing method of the Irwin type | system | group cement using the raw material for 2 or more types of component correction | amendment is proposed.

JP-A-9-309750

  By the way, since a metal has a high calorific value, if a metal powder treated with waste is used as a fuel, it can be effectively used as a resource for obtaining thermal energy. However, when the metal powder is burned, metal oxides are generated, and these are discharged as combustion ash, so that new waste is generated.

  In addition, a high-temperature combustion furnace is used for the combustion of metal powder. However, under the atmosphere in the furnace, metal powder and metal oxide adhere to various places in the furnace, leading to reduced heat transfer efficiency and equipment deterioration. There is a problem. For example, when metal powder is burned in a boiler and heat recovery is attempted, high temperature metal particles are fused to the boiler water pipe, thereby deteriorating the water pipe, which may cause a rupture accident.

  Furthermore, since the reactivity of metal becomes high when it is made into powder, there is a risk of causing a dust explosion when handling the metal, and there is also a problem that the waste treatment is dangerous.

  Therefore, the present invention has been made in view of the above-described problems in the conventional technology, and reuses metal waste safely and maximally without generating new waste or deteriorating equipment. An object of the present invention is to provide a metal powder fueling method and the like that can be used.

  In order to achieve the above object, the present invention is a method for converting a metal powder into a fuel, which cools a combustion gas extracted from an exhaust gas passage from an outlet duct of a cement firing calciner to an outlet duct of a preheater, The metal powder is conveyed using the cooled combustion gas, introduced into a cement firing furnace as a cement firing fuel, and burned in the cement firing furnace. Here, the metal powder may be discharged as waste.

  According to the present invention, since the metal powder containing the metal waste is used as the fuel for cement firing, it can be effectively used as a resource for obtaining thermal energy simultaneously with the treatment of the metal waste. Become. In addition, the metal oxide generated when the metal powder is burned becomes a part of the cement raw material and is eventually taken into the cement, so that the metal waste can be recycled without generating new waste. Can be used. Furthermore, in addition to being protected by refractory bricks, the inner walls of the cement firing furnace are covered with a raw material powder layer and coating, so even if high-temperature metal particles are fused, the equipment will not deteriorate. can do. In addition, air is extracted from the exhaust gas flow path from the calcining furnace outlet duct to the preheater outlet duct, and then the cooled combustion gas is used as a gas for conveying the metal powder, and the combustion gas has a low oxygen concentration. Moreover, since it is cooled to a predetermined temperature, the risk of dust explosion can be reduced.

  In the metal powder fueling method, the combustion gas extracted from the exhaust gas passage is supplied to a drying means for drying the hydrated waste, and the combustion gas is dried while the hydrated waste is dried by the drying means. Can be cooled. According to this method, it is economical to dry the hydrated waste and cool the combustion gas at the same time.

  In the metal powder fueling method, the combustion gas extracted from the exhaust gas passage can be cooled to 300 ° C. or lower. Of iron powder, aluminum powder, and silicon powder discharged as metal waste, the iron powder has the lowest ignition point, and its ignition point is about 310 ° C. By cooling the gas to 300 ° C. or lower, the risk of dust explosion can be greatly reduced.

  The present invention also relates to a fuel conversion system for metal powder, which is an extraction means for extracting combustion gas from an exhaust gas passage from an outlet duct of a cement firing calciner to an outlet duct of a preheater, and an extracted combustion gas A cooling means for cooling the metal, a conveying means for conveying the metal powder using the cooled combustion gas, and a cement firing furnace for firing the cement raw material using the conveyed metal powder as a fuel for cement firing. It is characterized by. According to the present invention, similarly to the above-described invention, it is possible to reuse metal waste safely and maximally without generating new waste or deteriorating equipment.

  In the metal powder fueling system, the cooling means may be a drying means for drying the hydrated waste using the combustion gas extracted from the exhaust gas passage. According to this configuration, the fuel gas can be cooled by an economical method.

  As described above, according to the present invention, a method for converting a metal powder into a fuel that can safely and maximally reuse metal waste without generating new waste or deteriorating equipment, etc. Can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a metal powder fueling system according to the present invention. The fueling system 1 is roughly divided into a main fuel tank 2, a sub fuel tank 3, a mixer 4, and a burner. 5, a cement kiln 10, a clinker cooler 11, a preheater 12, a calciner 13, a dryer 15, and the like, and is configured as a part of cement burning equipment. In the substance flow in the figure, a solid line indicates a solid flow such as raw fuel, and a broken line indicates a gas flow including gas such as combustion gas and powder.

  The cement kiln 10, the clinker cooler 11, the preheater 12, and the calcining furnace 13 have the same functions as those of a conventional cement manufacturing apparatus, and the cement raw material R supplied to the preheater 12 is preheated by the preheater 12, and the calcining furnace. After calcining at 13, it is fired at cement kiln 10.

  The main fuel tank 2 is provided for temporarily storing the main fuel, and stores pulverized coal obtained by drying and pulverizing coal. The main fuel tank 2 is additionally provided with a blower 7 for pumping pulverized coal discharged from the main fuel tank 2 and a pipe 6 for introducing the pulverized coal into the mixer 4.

  The auxiliary fuel tank 3 is provided for temporarily storing the auxiliary fuel, and stores metal powder brought into the cement manufacturing plant as waste. Metal powders that can be used as secondary fuel include iron powder, aluminum powder and silicon powder, as well as cutting scraps, cutting scraps, polishing scraps, Dalai powder, new cuttings and mechanicals, and aluminum recycling processing that occur during metal processing. There are aluminum dross powder generated at times, WSO (wire saw oil) solids, and the like. The particle size of the metal powder stored in the auxiliary fuel tank 3 is 0.01 μm or more and 1000 μm or less in terms of average particle size from the viewpoint of aggregation, reduction of caking, prevention of dust explosion, conveyance stability, etc. Is preferably 10 μm or more and 300 μm or less.

  The mixer 4 is provided to mix the pulverized coal introduced from the main fuel tank 2 and the metal powder introduced from the auxiliary fuel tank 3 at a predetermined ratio. The mixing ratio of the metal powder at this time is such that the fuel replacement ratio with respect to the entire pre-kiln fuel of the metal powder is obtained from the viewpoint of obtaining a certain effect of fuel replacement, while ensuring an appropriate flame condition. In terms of calorific value, it is preferably about 0.1% to 90%, more preferably about 10% to 50%.

  The dryer 15 is provided to dry high water content organic waste (hereinafter referred to as “water content waste”) such as high water content organic sludge. The dryer 15 includes the lower cyclone 12A to the second cyclone 12B. The combustion gas G extracted from the exhaust gas flow path to is supplied, and the dryer 15 dries the hydrated waste using the combustion gas G.

  The dryer 15 also functions as a cooling device for cooling the combustion gas G, and the combustion gas G having a temperature of about 800 to 900 ° C. is cooled to a predetermined temperature in the course of drying the hydrated waste. Since the ignition points of iron powder, aluminum powder, and silicon powder are about 310 ° C., about 640 ° C., and about 770 ° C., respectively, it is preferable to cool the combustion gas G to 300 ° C. or less in the dryer 15.

  The fan 16 is provided to introduce the combustion gas G from the preheater 12 to the dryer 15, and the fan 16 has a circulation duct for returning the exhaust gas to the exhaust gas flow path from the lowermost cyclone 12A to the second cyclone 12B. 17 and a pipe 18 for introduction into the blower 7 are attached.

  Next, the operation of the metal powder fueling system 1 having the above configuration will be described with reference to FIG.

  When the operation of the fueling system 1 is started, the combustion gas G extracted from the exhaust gas flow path between the lowermost cyclone 12A and the second cyclone 12B is introduced into the dryer 15, and the dryer 15 discards the water content. At the same time that the object is dried, the combustion gas G is cooled. The cooled combustion gas G circulates in the exhaust gas flow path via the fan 16 and the circulation duct 17 and is introduced into the blower 7 via the pipe line 18. The waste W dried by the dryer 15 may be processed in a cement manufacturing apparatus or may be processed outside the cement manufacturing apparatus.

  Next, the cooled combustion gas G is introduced into the blower 7 through the pipe line 18, and the metal powder of the auxiliary fuel tank 3 is pumped to the mixer 4. In parallel with this, the pulverized coal of the main fuel tank 2 is introduced into the mixer 4 via the pipe 6, and the metal powder and the pulverized coal are mixed in the mixer 4. Next, both mixed fuels are blown into the cement kiln 10 from the burner 5 and used for cement firing.

  According to the above configuration, since the metal powder as the metal waste is used as the cement firing fuel, it can be effectively used as a resource for obtaining thermal energy at the same time as the metal waste is treated.

  In the cement kiln 10, a metal oxide is generated when the metal powder is burned. The generated metal oxide becomes a part of the cement raw material in the firing process and is finally taken into the cement. . Therefore, metal waste can be reused without generating new waste. In particular, when the metal powder is iron powder, aluminum powder and silicon powder, since these oxides are main components of cement, a large amount of metal powder can be introduced, and more metal waste Can be processed.

  In addition, even if impurities are mixed in the metal powder, if the impurities are combustibles such as waste oil and waste plastics or transpiration such as water, it is not necessary to perform a separate separation process. It can be used as a fuel for cement firing, and the processing cost can be kept low.

In addition, by using metal powder as part of cement fired fuel, the amount of pulverized coal used as the main fuel can be reduced, so CO ₂ emissions can be reduced, and from the viewpoint of cement production. Even it is effective. Further, even if a trace amount of heavy metal, chlorine, or the like is mixed in the metal powder, if it is a cement firing furnace, it can be discharged out of the system by a chlorine bypass system, so there is no possibility of deteriorating cement quality.

  Furthermore, the inner wall of the cement kiln 10 is covered with a raw material powder layer and coating in addition to being protected by refractory bricks, so that even if high-temperature metal particles are fused, the equipment is prevented from deteriorating. can do.

  Moreover, the combustion gas G extracted from the exhaust gas flow path between the lowermost cyclone 12A and the second cyclone 12B is used as the gas for conveying the metal powder, and the combustion gas G is 2 to 8%. And the oxygen concentration is low, the risk of dust explosion can be reduced. For example, the critical oxygen concentrations of iron powder and silicon powder are about 10% and about 15%, respectively, and the combustion gas G has a lower oxygen concentration than any of them. The critical oxygen concentration of the aluminum powder is about 3% and is included in the range of the oxygen concentration of the combustion gas G extracted from the exhaust gas flow path. In the above configuration, the extracted combustion gas G is removed by the dryer 15. Since it uses as gas for conveyance after cooling, the temperature of combustion gas G when conveying metal powder is sufficiently lower than the ignition point of aluminum powder. Therefore, safety can be ensured even if aluminum powder is contained in the metal powder.

  In the above embodiment, the pulverized coal as the main fuel is first introduced from the main fuel tank 2 into the transport airflow from the blower 7 and is transported by the cooled combustion gas. The metal powder from the auxiliary fuel tank 3 was mixed, but the metal powder was first introduced into the transport airflow from the blower 7 and transported by the cooled combustion gas, and the main fuel was mixed by the downstream mixer. Also good. Moreover, the metal powder conveyed by the cooled combustion gas may be blown from a separate flow path in the same burner as the main fuel, or may be blown from a burner different from the main fuel.

  Moreover, in the said embodiment, although the case where metal powder was blown in from the kiln front part of the cement kiln 10 was demonstrated, the fuel which mixed pulverized coal and metal powder was supplied to the burner of the calciner 13, and calcined. Metal powder can also be blown into the furnace 13.

  Furthermore, in the above embodiment, the combustion gas G extracted from the exhaust gas flow path from the lowermost cyclone 12A to the second cyclone 12B is supplied to the dryer 15, but the second cyclone 12B further upstream of the preheater 12 is supplied. It is also possible to extract the combustion gas G from the exhaust gas flow path from the first cyclone 12C to the third cyclone 12C or from the third cyclone 12C to the fourth cyclone 12D and supply it to the dryer 15.

  In the above embodiment, the combustion gas G is cooled using the dryer 15 for drying the hydrated waste, but the combustion gas G is cooled using a heat exchanger type cooling device using cold air. May be.

It is the schematic which shows one Embodiment of the fueling system of the metal powder concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal powder fueling system 2 Main fuel tank 3 Sub fuel tank 4 Mixer 5 Burner 6 Pipe line 7 Blower 10 Cement kiln 11 Clinker cooler 12 Preheater 12A Bottom cyclone 12B Second cyclone 12C Third cyclone 12D Fourth cyclone 13 Calcination furnace 15 Dryer 16 Fan 17 Circulation duct 18 Pipe line

Claims (6)

  The combustion gas extracted from the exhaust gas flow path from the exit duct of the calcining furnace for cement firing to the exit duct of the preheater is cooled, and the cooled combustion gas is used to convey metal powder to burn the cement as a fuel for cement firing. A method for converting a metal powder into fuel, which is introduced into a furnace and burned in the cement firing furnace.   The method of claim 1, wherein the metal powder is discharged as waste.   The combustion gas extracted from the exhaust gas flow path is supplied to a drying means for drying the hydrated waste, and the combustion gas is cooled while the hydrated waste is dried by the drying means. 3. A method for converting a metal powder into a fuel according to 1 or 2.   The method for converting a metal powder into a fuel according to claim 1, 2 or 3, wherein the combustion gas extracted from the exhaust gas passage is cooled to 300 ° C or lower. An extraction means for extracting combustion gas from the exhaust gas flow path from the exit duct of the calcining furnace for cement firing to the exit duct of the preheater;
Cooling means for cooling the extracted combustion gas;
Conveying means for conveying the metal powder using the cooled combustion gas;
A metal powder fueling system comprising: a cement firing furnace for firing a cement raw material using the conveyed metal powder as a fuel for cement firing.   6. The metal powder fueling system according to claim 5, wherein the cooling means is a drying means for drying the hydrated waste using the combustion gas extracted from the exhaust gas passage.

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