JP2018083956A - Treatment device and treatment method for mercury-containing substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably, at a low cost, and in a short time, cool a mercury-removed substance obtained by removing mercury from a mercury-containing substance by volatilization.SOLUTION: Provided is a treatment device 1 for a mercury-containing substance comprising: an external heat kiln 4 heating mercury-containing dust D3 to volatilize mercury; an active carbon absorption tower 7 recovering the mercury from a mercury-containing gas G2 exhausted from the external heat kiln; a cooling apparatus 8 bringing mercury-removed dust D4 exhausted from the external heat kiln into contact with aluminum C for cooling and performing cooling; and a vibration screen apparatus 9 separating aluminum C1 for cooling from a mixture M exhausted from the cooling apparatus 8. The device may be provided with a circulation route returning the aluminum C1 for cooling separated in the vibration screen apparatus to the cooling apparatus. Further, it is possible that a heat exchanger 10 for recovering heat from the aluminum for cooling subjected to the vibration screen apparatus separation is provided, and aluminum C2 for cooling after the heat recovery is returned to the cooling apparatus 8 via the circulation route. It is also possible that a cooling apparatus further cooling the mercury-removed dust exhausted from the vibration screen apparatus is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus and method for treating mercury-containing substances such as dust recovered from exhaust gas from a preheater of a cement baking apparatus and ash generated when coal is burned in a thermal power plant.

  In recent years, various attempts have been made to reuse various materials. However, if a substance to be reused contains a harmful component, it is necessary to collect the harmful component in advance before reusing this material. . Mercury, which has a harmful effect on the human body and may cause air pollution, is a representative example of such harmful components. When reusing mercury-containing materials, it is natural to recover mercury from mercury-containing materials in advance. It is necessary to keep.

  By the way, also in the cement manufacturing field, an attempt to recycle various things is made actively, and the recycling of mercury-containing substances is included in them. For example, in Patent Document 1, dust (kiln dust) recovered from exhaust gas from a preheater of a cement firing device or ash (coal ash) generated when coal is burned at a thermal power plant is used as a cement raw material. Have been described. Since kiln dust and coal ash contain mercury, this document includes indirect heating of kiln dust etc. with an external heating rotary kiln (external heating kiln) to volatilize mercury in kiln dust etc., and mercury from gas containing volatilized mercury It is described that mercury-removed dust obtained by collecting and removing mercury with an external heat kiln is used as a cement raw material.

JP, 2006-108606, A

  In the processing method described in Patent Document 1, it is necessary to transport mercury-removed dust to a cement raw material process using a transport pipe. In order to eliminate the need for heat resistance measures for this transport pipe or to transport mercury-removed dust safely. It is necessary to cool the mercury removal dust discharged from the external heat kiln.

  However, since the mercury removal dust discharged from the external heat kiln is hot, for example, when cooling the mercury removal dust with water, a large amount of water is required to lower the temperature of the mercury removal dust, There was a problem that the cooling device had to be enlarged and it took a long time for cooling.

  In addition, the melted mercury removal dust is solidified by cooling and adheres to the inner wall of the cooling device such as the cooling zone of the external heat kiln, which may cause the cooling device to be blocked.

  Accordingly, the present invention has been made in view of the above-described problems in the prior art, and stably cools a mercury removing material obtained by volatilizing and removing mercury from a mercury-containing material at a low cost and in a short time. With the goal.

  In order to achieve the above object, the present invention is a processing apparatus for a mercury-containing substance, the heating apparatus for heating the mercury-containing substance to volatilize the mercury contained in the substance, and the mercury-containing material discharged from the heating apparatus. Mercury recovery device for recovering mercury from gas; cooling device for contacting mercury cooling material discharged from heating device with solid cooling medium; cooling; mercury removing material discharged from cooling device; and solid And a separation device for separating the solid cooling medium from the mixture of the gaseous cooling medium.

  According to the present invention, since the mercury removing substance is cooled by contacting with the solid cooling medium, the temperature of the mercury removing substance can be lowered without using a large amount of water, and the mercury removing substance can be reduced in cost and cost. It can be cooled in a short time.

  In the mercury-containing substance processing apparatus, by providing a circulation route for returning the solid cooling medium separated by the separation apparatus to the cooling apparatus, the use cost of the cooling medium can be kept low.

  Further, a heat recovery device for recovering heat from the solid cooling medium separated by the separation device is provided, and the heat of the mercury-containing substance is recovered by returning the solid cooling medium after the heat recovery to the cooling device through the circulation route. Can be used effectively.

  Furthermore, by providing a cooling device for further cooling the mercury removing material discharged from the separation device, the mercury removing material can be reliably cooled.

  The present invention is also a method for treating a mercury-containing substance, wherein the mercury-containing substance is heated to volatilize the mercury contained in the substance, and the mercury is recovered from the gas containing the volatilized mercury. The mercury removing material obtained by volatilizing mercury from the substrate is cooled by contacting with the solid cooling medium, and the solid cooling medium is separated from the mixture of the mercury removing substance and the solid cooling medium.

  According to the present invention, similar to the above-described invention, the mercury removing substance is cooled by contacting with a solid cooling medium, so that the temperature of the mercury removing substance can be lowered without using a large amount of water. The substance can be cooled at a low cost and in a short time.

  Moreover, the use cost of a cooling medium can be restrained low by making the solid-state cooling medium isolate | separated from the said mixture contact the said mercury removal substance again. Furthermore, if heat is recovered from the solid cooling medium separated from the mixture and then brought into contact with the mercury removing substance again, the heat of the mercury-containing substance can be effectively utilized.

  Further, by further cooling the mercury removing material after separating the solid cooling medium from the mixture, the mercury removing material can be reliably cooled.

  As the solid cooling medium, a metal larger than the mercury removing material can be used. As a result, the solid cooling medium can be separated from the mixture of the mercury removing substance and the solid cooling medium using a vibrating sieve or the like, and can be efficiently cooled by using a metal having high thermal conductivity. In addition, since the metal has an effect of promoting wear on the solid surface, it is possible to prevent the cooling device from generating coating, and to stably cool the mercury removing substance.

  As the mercury-containing substance, 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 can be used as the cement raw material.

  As described above, according to the present invention, a mercury removing material obtained by volatilizing and removing mercury from a mercury-containing material can be stably cooled in a low cost and in a short time.

1 is an overall configuration diagram showing an embodiment of a mercury-containing substance processing apparatus according to the present invention.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings. In the following, a case will be described as an example where dust (kiln dust) recovered from the exhaust gas of the preheater of the cement firing apparatus is treated as a mercury-containing substance in the mercury-containing substance treatment apparatus according to the present invention.

  FIG. 1 shows an embodiment of a mercury-containing substance processing apparatus according to the present invention. This processing apparatus 1 includes a hopper 2 for storing kiln dust D1, a screw for conveying kiln dust D1 supplied from hopper 2, and the like. From the conveyor 3, the external heat kiln 4 that indirectly heats the mercury-containing dust D3 supplied from the screw conveyor 3, the bag filter 5 that collects dust from the mercury-containing gas G2 discharged from the external heat kiln 4, and the bag filter 5 Discharge from the fan 6 which adds air A to the exhausted mercury-containing gas G3 to form the mercury dilution gas G4, the activated carbon adsorption tower 7 which adsorbs and recovers the mercury contained in the mercury dilution gas G4, and the external heat kiln 4 A cooling device 8 that cools the mercury removal dust D4 mixed with cooling aluminum (solid cooling medium, hereinafter abbreviated as “cooling medium”) C; A vibrating screen apparatus 9 for separating the coolant C1 from the discharged mixture M from 8, comprises a heat exchanger 10 for performing heat exchange with the cooling medium C1 discharged from the vibrating screen apparatus 9.

  An external heat kiln 4 as a heating device is provided so as to surround the kiln 4a, a jacket 4b in which a heating medium such as high-temperature gas is introduced to heat the outer surface of the kiln 4a, and a screw conveyor. 3 includes a dust supply unit 4c to which mercury-containing dust D3 is supplied, a gas introduction unit 4d to which carrier gas G1 supplied from a carrier gas supply device (not shown) is introduced, and mercury volatilized from the mercury-containing dust D3. A gas discharge unit 4e for discharging the mercury-containing gas G2 and a dust discharge unit 4f for discharging the mercury-removed dust D4 from which mercury has been volatilized and removed from the mercury-containing dust D3.

  The external heat kiln 4 is an indirect heating device that indirectly heats the mercury-containing dust D3, which is a heating object, without contacting the heating medium. By using the external heat kiln 4 that is an indirect heating device as a heating device for the mercury-containing dust D3, the mercury-containing dust D3 can be uniformly heated without using a large amount of a heating medium such as a gas. The amount of the gas G1 and the mercury-containing gas G2 can be reduced. For this reason, the external heat kiln 4, the bag filter 5, and the activated carbon adsorption tower 7 through which these gases pass can be reduced in size. Moreover, it can prevent that a heating medium contains mercury by contact with mercury containing dust D3 and a heating medium, and can process a heating medium easily.

  Moreover, in the external heat kiln 4, the gas discharge part 4e and the dust discharge part 4f are provided separately, whereby the mercury and dust in the mercury-containing dust D3 can be discharged separately from the external heat kiln 4. Thereby, even if the carrier gas G1 introduced into the external heat kiln 4 is small, mercury volatilized in the kiln 4a can be transported to the activated carbon adsorption tower 7 as the mercury-containing gas G2, and the external heat kiln 4 and the bag filter 5 can be transported. In addition, the amount of gas introduced into the activated carbon adsorption tower 7 is reduced, and the equipment cost can be reduced by downsizing these apparatuses.

  In addition, it can replace with the external heat kiln 4, and can also use the heating apparatus in which the discharge part of mercury containing gas G2 and mercury removal dust D4 is common. In this case, when the concentration of the mercury removal dust D4 in the mercury-containing gas G2 becomes high, the mercury removal dust D4 can be recovered by the dust collector.

  Moreover, it can replace with the external heat kiln 4 and can use another kind of indirect heating apparatus, and can also use the direct heating apparatus which contacts a heating target object with a heating medium and heats it directly. Furthermore, as the carrier gas G1, for example, an inert gas or air can be used.

  As the bag filter 5 as a dust collector, a high heat-resistant bag filter having heat resistance up to about 900 ° C. or a normal heat filter can be used. Most of the dust from which mercury has been removed from the mercury-containing dust D3 is discharged from the dust discharge part 4f, but a part of this dust is discharged from the gas discharge part 4e together with the mercury-containing gas G2, and such dust Is collected in the bag filter 5. A dust collector other than the bag filter 5 can also be used.

The fan 6 is provided for diluting the mercury-containing gas G3 and adjusting the mercury concentration of the mercury-containing gas G3 to a concentration suitable for adsorption in the activated carbon adsorption tower 7 (1,000 mg / m ³ or less). Here, by setting the temperature of the air A supplied from the fan 6 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 7 as a mercury recovery device is provided for adsorbing and recovering mercury in the mercury dilution gas G4. As the activated carbon used in the activated carbon adsorption tower 7, it is desirable to select activated carbon that is particularly excellent in mercury recovery ability among commercially available activated carbon, and specifically, a sulfur impregnation treatment adjusted for mercury adsorption is performed. The activated carbon is preferred. A mercury recovery device other than the activated carbon adsorption tower 7 can also be used.

  The cooling device 8 is provided to cool the mercury removal dust D4 discharged from the dust discharge portion 4f of the external heat kiln 4 in contact with the cooling medium C. As the cooling device 8, a device such as a screw conveyor that transports the mercury removing dust D4 while being in contact with the cooling medium C and cools the outside of the casing with cooling water can be used. By using a transportable device, it can be transported while cooling.

  As the cooling device 8, a device that does not have a transport function and only has a paddle, a blade, or the like that rotates the mercury removal dust D4 and the cooling medium C can be used. Further, the mercury removal dust D4 can be used as the cooling medium C. A device that cools indirectly or directly with cooling water or the like can also be used.

  The vibration sieve device 9 as a separation device is provided to separate the cooling medium C1 from the mixture M discharged from the cooling device 8. A device other than the vibration sieve device 9 can also be used as the separation device.

  The heat exchanger 10 as a heat recovery device cools the cooling medium C1 by exchanging heat between the cooling medium C1 separated by the vibration sieve device 9 and air, and recovers heat from the cooling medium C1. To be provided.

  Next, the operation of the mercury-containing substance processing apparatus 1 having the above configuration will be described with reference to FIG.

  High temperature gas is introduced into the jacket 4b of the external heat kiln 4 to heat the jacket 4b, and the jacket 4b having a high temperature heats the outer surface of the kiln 4a, whereby the inside of the kiln 4a is indirectly heated. Next, the kiln dust D1 stored in the hopper 2 is supplied from the dust supply unit 4c to the kiln 4a via the screw conveyor 3. The kiln dust as the mercury-containing dust D3 supplied to the kiln 4a is heated in contact with the high temperature inner surface of the kiln 4a, and the mercury contained in the kiln dust volatilizes.

  On the other hand, the carrier gas G1 is introduced into the kiln 4a from the gas introduction part 4d, the mercury volatilized in the kiln 4a is conveyed to the gas discharge part 4e by the carrier gas G1, and these are converted into the gas discharge part 4e as the mercury containing gas G2. To discharge from. Further, by introducing the mercury-containing gas G2 into the bag filter 5 and collecting the dust, the mercury-containing gas G2 is separated into the mercury-containing gas G3 and the mercury removal dust D2.

  Air A is added from the fan 6 to the mercury-containing gas G3 discharged from the bag filter 5, and the mercury-containing gas G3 is diluted to form a mercury dilution gas G4. The mercury in the mercury dilution gas G4 is adsorbed by the activated carbon adsorption tower 7. to recover. The mercury removal gas G5 discharged from the activated carbon adsorption tower 7 is discharged to the atmosphere after appropriate exhaust gas treatment. On the other hand, the mercury removal dust D2 collected by the bag filter 5 is returned to the screw conveyor 3 and supplied to the dust supply unit 4c as the mercury-containing dust D3 together with the kiln dust D1 supplied to the screw conveyor 3.

  Further, the mercury-removed dust D4 from which mercury has been removed from the mercury-containing dust D3 is discharged from the dust discharge part 4f, supplied to the cooling device 8 together with the cooling medium C, and brought into contact with each other to cool the mercury-removed dust D4. To do. Thereafter, the mixture M is separated into the mercury removal dust D4 and the heated cooling medium C1 in the vibration sieve device 9. Here, since the mercury removal dust D4 contains almost no mercury, there is no possibility of increasing the mercury concentration of the cement kiln exhaust gas even if this is used as a cement raw material.

  On the other hand, the heated cooling medium C1 is recovered and cooled in the heat exchanger 10 and then returned to the cooling device 8 via the circulation route 11 as cooling medium C2 for cooling the mercury removal dust D4. Used. Thereby, the usage cost of the cooling medium C can be kept low while effectively using the heat of the mercury removal dust D4.

  As described above, in the above embodiment, the mercury removal dust D4 is supplied to the cooling device 8 together with the cooling medium C, whereby the mercury removal dust D4 is brought into contact with the cooling medium C to cool the mercury removal dust. Thereby, since the cooling device 8 can be reduced in size without using a large amount of water, the cost required for cooling the mercury removal dust D4 can be kept low, and the mercury removal dust D4 can be reduced in a short time. Can be cooled. Further, the cooling medium C has an effect of promoting wear on the solid surface, so that the cooling device 8 can be prevented from being coated.

  In the above embodiment, the temperature of the mercury removing dust D4 discharged from the external heat kiln 4 is 300 ° C. or higher and 550 ° C. or lower, and this temperature is preferably lowered to 150 ° C. or lower by the cooling device 8. When the mercury removal dust D4 is not sufficiently cooled, it can be returned to the cooling device 8 and cooled again. Further, a separate cooling device may be provided after the cooling device 8.

  Furthermore, as the cooling medium C, other metals and ceramics can be used besides aluminum, but those having high thermal conductivity are preferably used from the viewpoint of cooling efficiency. Moreover, since the cooling medium C isolate | separates with the vibration sieve apparatus 9, the thing larger than the mercury removal dust D4 is selected. However, if the particle size is too large, it takes time for heat exchange and the cooling effect is reduced, so the appropriate size is set. As the shape of the cooling medium C, a block shape, a spherical shape, or a plate shape can be used.

  Note that the heat exchanger 10 is not an essential component, and when the heat of the cooling medium C1 is not used, the heated cooling medium C1 may be naturally cooled.

  In addition, although the said embodiment demonstrated the case where kiln dust D1 was processed, if it is a substance containing mercury, such as ash (coal ash) generated when coal is burned in a thermal power plant, other substances Can also be processed.

DESCRIPTION OF SYMBOLS 1 Mercury-containing substance processing apparatus 2 Hopper 3 Screw conveyor 4 External heat kiln 4a Kiln 4b Jacket 4c Dust supply part 4d Gas introduction part 4e Gas discharge part 4f Dust discharge part 5 Bag filter 6 Fan 7 Activated carbon adsorption tower 8 Cooling device 9 Vibration Sieve device 10 Heat exchanger 11 Circulation route A Air C, C1, C2 Cooling medium D1 Kiln dust D2 Mercury removal dust D3 Mercury-containing dust D4 Mercury removal dust D5 Mercury removal dust G1 Carrier gas G2 Mercury-containing gas G3 Mercury-containing gas G4 Mercury dilution Gas G5 Mercury removal gas M Mixture

Claims (10)

A heating device for heating the mercury-containing substance to volatilize the mercury contained in the substance;
A mercury recovery device for recovering mercury from the mercury-containing gas discharged from the heating device;
A cooling device for cooling the mercury-removing substance discharged from the heating device by contacting with a solid cooling medium;
An apparatus for treating a mercury-containing material, comprising: a separation device for separating the solid cooling medium from the mixture of the mercury removing material and the solid cooling medium discharged from the cooling device.   The apparatus for treating a mercury-containing substance according to claim 1, further comprising a circulation route for returning the solid cooling medium separated by the separation device to the cooling device.   The heat recovery apparatus which collects heat from the solid cooling medium separated by the separation apparatus is provided, and the solid cooling medium after heat recovery is returned to the cooling apparatus through the circulation route. Mercury-containing material processing equipment.   The apparatus for treating a mercury-containing material according to claim 1, 2 or 3, further comprising a cooling device for further cooling the mercury removing material discharged from the separation device. Heating the mercury-containing substance to volatilize the mercury contained in the substance,
Recovering mercury from the volatilized mercury-containing gas,
A mercury-removing substance obtained by volatilizing mercury from the mercury-containing substance is cooled by contacting with a solid cooling medium,
A method for treating a mercury-containing material, comprising separating the solid cooling medium from a mixture of the mercury removing substance and the solid cooling medium.   6. The method for treating a mercury-containing material according to claim 5, wherein the solid cooling medium separated from the mixture is brought into contact with the mercury removing material again.   The method for treating a mercury-containing material according to claim 6, wherein heat recovery is performed from the solid cooling medium separated from the mixture, and then the mercury-removing material is contacted again.   The method for treating a mercury-containing substance according to claim 5, 6 or 7, further comprising cooling the mercury removing substance after separating the solid cooling medium from the mixture.   The method for treating a mercury-containing substance according to any one of claims 5 to 8, wherein a metal larger than the mercury removing substance is used as the solid cooling medium. As the mercury-containing material, using dust collected from the exhaust gas of the preheater of the cement baking apparatus or ash generated when coal is burned at a thermal power plant,
The method for treating a mercury-containing substance according to any one of claims 5 to 9, wherein the mixture after cooling is used as a cement raw material.

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