JP2018015688A - Processor and processing method for granular powder adsorbing mercury - Google Patents

Abstract

[Problem] To process a mercury-adsorbed granular material at a low cost while maintaining a high mercury removal rate from the mercury-adsorbed granular material. A classification device 2 for classifying a granular material D adsorbing mercury and separating it into a coarse particle side dust C and a fine particle side dust F; and heating the fine particle side dust F discharged from the classification device 2; A heating device 5 for volatilizing mercury contained in the fine particle side dust F, a mercury recovery device 8 for recovering mercury from the mercury-containing gas G2 discharged from the heating device 5, and a classification device for the fine particles D2 discharged from the heating device 5 The processing apparatus 1 of the granular material which adsorb | sucked mercury provided with the mixing cooling apparatus 9 cooled while mixing with the coarse grain side dust C discharged | emitted from 2. FIG. Instead of the mixing cooling device 9, a mixing device that mixes the fine particles D2 discharged from the heating device 5 with the coarse particle side dust C discharged from the classification device 2, and a cooling device that cools the mixture discharged from the mixing device Can be provided. [Selection] Figure 1

Description

  The present invention relates to an apparatus and a method for treating dust particles collected from exhaust gas from a preheater of a cement baking apparatus, and particles adsorbed with mercury such as ash generated when coal is burned in a thermal power plant.

  In the cement manufacturing field, waste is being used as a raw material for cement, but dust (kiln dust) recovered from the exhaust gas from the preheater of the cement firing equipment and ash (coal ash) generated when coal is burned at a thermal power plant ) And the like adsorbed mercury as a cement material, the mercury concentration of the cement kiln exhaust gas may increase and cause air pollution.

  Therefore, for example, in Patent Document 1, powder particles adsorbed with mercury such as kiln dust and coal ash are indirectly heated with an external heating rotary kiln (external heat kiln) to volatilize and volatilize mercury in the powder particles. It is described that mercury is recovered from a gas containing mercury and the mercury-removed dust obtained by removing mercury with an external heat kiln is used as a cement raw material.

JP, 2006-108606, A

  However, although the processing method described in Patent Document 1 can efficiently remove mercury from mercury-containing powder particles, the powder containing mercury is heated and heated to a high temperature. In order to cool a granular material, there existed a problem that the cost required for the heating and cooling process of the granular material containing mercury increased.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and it is possible to reduce the cost of a mercury-adsorbed granular material while maintaining a high mercury removal rate from the mercury-adsorbed granular material. The purpose is to process.

  In order to achieve the above object, the present invention is an apparatus for treating a granular material adsorbed with mercury, classifying the granular material adsorbed with mercury and separating it into coarse particles and fine particles, and the classification A heating device for heating the fine particles discharged from the apparatus to volatilize mercury contained in the fine particles, a mercury recovery device for recovering mercury from the mercury-containing gas discharged from the heating device, and a discharge from the heating device And a mixing cooling device that cools the fine particles while mixing with the coarse particles discharged from the classification device. Here, “cooling while mixing” includes both cooling the fine particles only by mixing with the coarse particles and mixing the fine particles with the coarse particles and cooling with a cooling medium other than the coarse particles.

  In addition, the present invention is a processing apparatus for a granular material adsorbing mercury, classifying the granular material adsorbed mercury and separating it into coarse particles and fine particles, and discharged from the classification device A heating device for heating fine particles to volatilize mercury contained in the fine particles, a mercury recovery device for recovering mercury from a mercury-containing gas discharged from the heating device, and a classification device for collecting fine particles discharged from the heating device And a cooling device for cooling the mixture discharged from the mixing device. The mixing device mixes with the coarse particles discharged from the mixing device.

  ADVANTAGE OF THE INVENTION According to this invention, this granular material can be processed at low cost, maintaining the mercury removal rate from the granular material which adsorb | sucked mercury high.

  Furthermore, the present invention is a method for treating a mercury-adsorbed granular material, wherein the mercury-adsorbed granular material is classified into coarse particles and fine particles, and the fine particles obtained by the classification are heated. Then, the mercury contained in the fine particles is volatilized, the mercury is recovered from the gas containing the volatilized mercury, and the fine particles obtained by removing the mercury from the fine particles are mixed with the coarse particles obtained by the classification and cooled. It is characterized by doing. “Cooling while mixing” includes both cooling the fine particles only by mixing with the coarse particles and mixing the fine particles with the coarse particles and cooling them with a cooling medium other than the coarse particles.

  The present invention is also a method for treating mercury-adsorbed granular material, wherein the granular material adsorbed mercury is classified into coarse particles and fine particles, and the fine particles obtained by the classification are heated. The mercury contained in the fine particles is volatilized, the mercury is recovered from the gas containing the volatilized mercury, the fine particles obtained by removing the mercury from the fine particles are mixed with the coarse particles obtained by the classification, The mixture obtained by mixing is cooled.

  According to the present invention, as in the above-described invention, the granular material can be processed at low cost while maintaining a high mercury removal rate from the granular material adsorbed with mercury.

  In addition, the classification point in the classification can be 1.0 μm or more and 10 μm or less. Further, as the powder adsorbed mercury, dust collected from the exhaust gas of the preheater of the cement baking apparatus or ash generated when coal is burned in a thermal power plant, the mixture after cooling is used as a cement raw material Can be used.

  As described above, according to the present invention, a mercury-adsorbed granular material can be processed at a low cost while maintaining a high mercury removal rate from the mercury-adsorbed granular material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows one Embodiment of the processing apparatus of the granular material which adsorb | sucked the mercury based on this invention.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. In the following description, an example of processing dust (kiln dust) collected from the exhaust gas of a preheater of a cement baking apparatus as the powder in the processing apparatus for powder adsorbed with mercury according to the present invention will be described.

  FIG. 1 shows an embodiment of a processing apparatus for a granular material adsorbing mercury according to the present invention. This processing apparatus 1 classifies kiln dust D into fine particle dust F and coarse particle dust C. The cyclone 2 to be separated, the hopper 3 for storing the fine particle side dust F discharged from the cyclone 2, the screw conveyor 4 for conveying the fine particle side dust F supplied from the hopper 3, and the mercury supplied from the screw conveyor 4 Air A is added to the external heat kiln 5 for heating the contained dust D1, the bag filter 6 for collecting dust from the mercury-containing gas G2 discharged from the external heat kiln 5, and the mercury-containing gas G3 discharged from the bag filter 6. The fan 7 which is the mercury dilution gas G4, the activated carbon adsorption tower 8 which adsorbs and recovers the mercury contained in the mercury dilution gas G4, and the mercury removal dust D2 discharged from the external heat kiln 5 are supported. While mixing with discharged coarse side dust C from Kron 2 and a mixing cooler 9 for cooling.

  A cyclone 2 as a classifying device is provided for classifying kiln dust D and separating it into fine particle side dust F and coarse particle side dust C. The classification point of the cyclone 2 is preferably 1.0 μm or more and 10 μm or less. In addition, it can replace with the cyclone 2 and can also use another kind of classification apparatus.

  An external heat kiln 5 as a heating device includes a rotary kiln 5a, a jacket 5b that is provided so as to surround the kiln 5a, a heating medium such as a high-temperature gas is introduced, and heats the outer surface of the kiln 5a, and a screw conveyor 4, a dust supply unit 5c to which mercury-containing dust D1 is supplied, a gas introduction unit 5d to which a carrier gas G1 supplied from a carrier gas supply device (not shown) is introduced, and mercury volatilized from the mercury-containing dust D1 A gas discharge unit 5e that discharges the mercury-containing gas G2, and a dust discharge unit 5f that discharges the mercury-removed dust D2 generated by removing and evaporating mercury from the mercury-containing dust D1.

  In addition, it can replace with the external heat kiln 5, and can use another kind of heating apparatus. As this heating device, either an indirect heating device that indirectly heats an object to be heated without contacting the heating medium or a direct heating device that directly heats the object to be heated while contacting the heating medium is used. You can also. As the carrier gas G1, for example, an inert gas or air can be used.

  For the bag filter 6 as a dust collector, a high heat-resistant bag filter having heat resistance up to about 900 ° C. or a normal heat-resistant bag filter can be used. Most of the dust after the mercury is removed from the mercury-containing dust D1 is discharged from the dust discharge portion 5f, but the remaining portion is discharged from the gas discharge portion 5e together with the mercury-containing gas G2, and is discharged by the bag filter 6. Collected. In addition, it can replace with the bag filter 6 and can also use another kind of dust collector.

The fan 7 is provided for diluting the mercury-containing gas G3 to adjust the mercury concentration of the mercury-containing gas G3 to a concentration suitable for adsorption by the activated carbon adsorption tower 8 (1,000 mg / m ³ or less). Here, by setting the temperature of the air A supplied from the fan 7 to 20 ° C. or more and 80 ° C. or less, it is possible not only to dilute the mercury-containing gas G3 but also to cool it. Can be increased. In addition, if it is a gas for dilution, things other than the air A can be used, for example, an inert gas can be used.

  The activated carbon adsorption tower 8 as a mercury recovery device is provided for adsorbing and recovering mercury in the mercury dilution gas G4. In addition, it can replace with the activated carbon adsorption tower 8, and can also provide another kind of mercury collection | recovery apparatus.

  The mixing and cooling device 9 cools the mercury-removed dust D2 discharged from the dust discharge portion 5f of the external heat kiln 5 while mixing with the coarse particle side dust C discharged from the cyclone 2 and not heated by the external heat kiln 5. Provided for. As the mixing and cooling device 9, a device that transports the mercury-removed dust D2 and the coarse grain side dust C while mixing them and cools the outside of the casing with cooling water, such as a screw conveyor, can be used. . By using a transportable device, it can be transported while cooling.

  As the mixing and cooling device 9, it is possible to use a device that does not have a transport function and only mixes the mercury removal dust D <b> 2 and the coarse grain side dust C using rotating paddles, blades, and the like. A device that cools indirectly or directly with cooling water or the like while mixing D2 and coarse particle side dust C can also be used.

  Next, the operation of the processing apparatus 1 for the granular material having adsorbed mercury having the above-described configuration will be described with reference to FIG.

  The kiln dust D is classified by the cyclone 2 and separated into the fine particle side dust F and the coarse particle side dust C having a high mercury content, and the fine particle side dust F is stored in the hopper 3.

  High temperature gas is introduced into the jacket 5b of the external heat kiln 5 to heat the jacket 5b, and the jacket 5b having a high temperature heats the outer surface of the kiln 5a, thereby indirectly heating the inside of the kiln 5a. Next, the fine particle side dust F stored in the hopper 3 is supplied as the mercury-containing dust D1 from the dust supply unit 5c to the kiln 5a via the screw conveyor 4. The mercury-containing dust D1 supplied to the kiln 5a is heated in contact with the high temperature inner surface of the kiln 5a, and the mercury contained in the mercury-containing dust D1 is volatilized.

  On the other hand, the carrier gas G1 is introduced into the kiln 5a from the gas introduction part 5d, the mercury volatilized in the kiln 5a is conveyed to the gas discharge part 5e by the carrier gas G1, and these are converted into the gas discharge part 5e as the mercury-containing gas G2. To discharge from. Further, the mercury-containing gas G2 is separated into the mercury-containing gas G3 and the mercury removal dust D3 by introducing the mercury-containing gas G2 into the bag filter 6 and collecting the dust.

  Air A is added from the fan 7 to the mercury-containing gas G3 discharged from the bag filter 6, and the mercury-containing gas G3 is diluted to form a mercury-diluting gas G4. The mercury in the mercury-diluting gas G4 is adsorbed by the activated carbon adsorption tower 8. to recover. The mercury removal gas G5 discharged from the activated carbon adsorption tower 8 is discharged to the atmosphere after appropriate exhaust gas treatment. On the other hand, the mercury removal dust D3 collected by the bag filter 6 is returned to the screw conveyor 4 and supplied to the dust supply unit 5c as the mercury-containing dust D1 together with the fine particle side dust F supplied to the screw conveyor 4.

  Further, the mercury-removed dust D2 after the mercury is removed from the mercury-containing dust D1 is discharged from the dust discharge part 5f, supplied to the mixing and cooling device 9 together with the coarse particle side dust C, and cooled while mixing these. . The mixture M discharged from the mixing cooling device 9 is used as a cement raw material. The temperature of the mercury removal dust D2 discharged from the external heat kiln 5 is 300 ° C. or more and 550 ° C. or less, and the temperature of the mercury removal dust D2 is preferably lowered to 150 ° C. or less by the mixing and cooling device 9.

  Further, in the mixing and cooling device 9, the coarse grain side dust C is heated by the heat of the high temperature mercury removal dust D2 discharged from the external heat kiln 5, and the mercury contained in the coarse grain side dust C is volatilized and mixed and cooled. Since it stays inside the apparatus 9, the mercury is recovered from the gas containing mercury that is volatilized inside the mixed cooling apparatus 9. For example, the gas containing mercury volatilized inside the mixed cooling device 9 can be merged with the mercury-containing gas G2, and both can be processed by the bag filter 6 or the activated carbon adsorption tower 8. Further, a gas containing mercury that is volatilized inside the mixed cooling device 9 may be directly introduced into the bag filter 6 or the activated carbon adsorption tower 8.

  As described above, in the above embodiment, the mercury removal dust D2 after the mercury is removed from the fine particle side dust F which is a part of the kiln dust D is mixed with the coarse particle side dust C which is also a part of the kiln dust D. Therefore, the cooling medium such as water is not used or the usage amount of the cooling medium can be kept low, and the cost required for cooling the fine particle side dust F can be reduced.

  In the above embodiment, the mercury cooling dust D2 is cooled while being mixed with the coarse particle side dust C by the mixing cooling device 9, but instead of the mixing cooling device 9, a mixing device and a cooling device are separately provided, and the mercury is removed. The removal dust D2 and the coarse particle side dust C may be supplied to a mixing device and mixed, and the mixture discharged from the mixing device may be cooled by a cooling device.

  Further, the fine particle side dust F having a high mercury content is heated by the external heat kiln 5 to volatilize and remove the mercury, and the coarse particle side dust C is heated by the heat of the high temperature mercury removal dust D2 by the mixing cooling device 9. Since mercury is also volatilized and removed from coarse particle side dust C, mercury can be removed from each of fine particle side dust F and coarse particle side dust C, and mercury can be volatilized and removed from kiln dust D at a high removal rate. .

  Further, in the above embodiment, the coarse dust D in the kiln dust D is not supplied to the external heat kiln 5 but only the fine dust F is supplied. However, the fine dust F has a small particle size, so the fine dust D F can be effectively heated by the external heat kiln 5.

  In addition, in the said embodiment, although the case where kiln dust D was processed was demonstrated, if it is the granular material which adsorb | sucked mercury, such as ash (coal ash) which generate | occur | produces when burning coal in a thermal power plant, It is also possible to process other granular materials.

DESCRIPTION OF SYMBOLS 1 Processing apparatus of the granular material which adsorbed mercury 2 Cyclone 3 Hopper 4 Screw conveyor 5 External heat kiln 5a Kiln 5b Jacket 5c Dust supply part 5d Gas introduction part 5e Gas discharge part 5f Dust discharge part 6 Bag filter 7 Fan 8 Activated carbon adsorption Tower 9 Mixing cooling device A Air C Coarse side dust D Kiln dust D1 Mercury-containing dust D2 Mercury removal dust D3 Mercury removal dust F Fine particle side dust G1 Carrier gas G2 Mercury-containing gas G3 Mercury-containing gas G4 Mercury diluted gas G5 Mercury removal gas M blend

Claims (6)

A classification device for classifying powder particles adsorbed with mercury and separating them into coarse particles and fine particles;
A heating device that heats the fine particles discharged from the classification device to volatilize mercury contained in the fine particles;
A mercury recovery device for recovering mercury from the mercury-containing gas discharged from the heating device;
An apparatus for treating a mercury-adsorbed granular material, comprising: a mixing and cooling device that cools the fine particles discharged from the heating device while mixing the fine particles discharged from the classification device. A classification device for classifying powder particles adsorbed with mercury and separating them into coarse particles and fine particles;
A heating device that heats the fine particles discharged from the classification device to volatilize mercury contained in the fine particles;
A mercury recovery device for recovering mercury from the mercury-containing gas discharged from the heating device;
A mixing device for mixing the fine particles discharged from the heating device with the coarse particles discharged from the classification device;
And a cooling device for cooling the mixture discharged from the mixing device. Classification of the granular material adsorbed with mercury to separate into coarse particles and fine particles,
Heating the fine particles obtained by the classification to volatilize mercury contained in the fine particles,
Recovering mercury from the volatilized mercury-containing gas,
A method for treating a mercury-adsorbed granular material, wherein the fine particles obtained by removing mercury from the fine particles are cooled while being mixed with the coarse particles obtained by the classification. Classification of the granular material adsorbed with mercury to separate into coarse particles and fine particles,
Heating the fine particles obtained by the classification to volatilize mercury contained in the fine particles,
Recovering mercury from the volatilized mercury-containing gas,
Mixing the fine particles obtained by removing mercury from the fine particles with the coarse particles obtained by the classification,
A method for treating a particulate adsorbed with mercury, comprising cooling the mixture obtained by the mixing.   The method for treating a granular material adsorbing mercury according to claim 3 or 4, wherein a classification point in the classification is set to 1.0 µm or more and 10 µm or less. Using the dust collected from the exhaust gas of the preheater of the cement firing device or the ash generated when the coal is burned at the thermal power plant as the mercury adsorbed powder,
The method for treating a particulate adsorbed with mercury according to claim 3, 4 or 5, wherein the mixture after cooling is used as a cement raw material.

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