JP2017060905A - Processing apparatus and method of cement kiln exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently process a cement kiln exhaust gas at a low cost while effectively utilizing heat energy of an ecological cement kiln exhaust gas.SOLUTION: A cement kiln exhaust gas processing apparatus 1 comprises: a heat recovery device (boiler) 4 for recovering heat from the exhaust gas G1 of an ecological cement kiln; an activated carbon addition device 7 for adding activated carbon AC1 into the exhaust gas G2 of the heat recovery device; a dust collector 8 for collecting dust in an exhaust gas G5 added with the activated carbon AC1; a reheating device 9 for reheating the exhaust gas G6 of the dust collector 8; a catalyst device 10 removing harmful substances in a reheated exhaust gas G7; and a wet dust collector (wet scrubber) 11 for collecting dust in the exhaust gas G8 of the catalyst device in a wet state. In the reheating device 9, reheating can be performed by using heat recovered in the heat recovery device 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus and a method for treating exhaust gas from an ecocement kiln for producing ecocement.

  Ecocement is manufactured using incineration ash from municipal waste and sewage sludge and conventional cement raw materials. As shown in FIG. 2, the ecocement firing apparatus includes a cement kiln 2 and a clinker cooler 3 that cools the cement clinker manufactured by the cement kiln 2. However, in order to suppress resynthesis of dioxins, The entire amount of the exhaust gas G11 of the cement kiln 2 is cooled by the exhaust gas cooling facility 22.

  In addition, in order to remove harmful substances derived from chlorine, heavy metals, etc. contained in incineration ash from the exhaust gas G12 of the exhaust gas cooling facility 22, the exhaust gas G12 is exhausted from the cyclone 5 with the coarse powder C and the exhaust gas G13 containing the fine powder F. Then, the fine dust F is removed from the exhaust gas G13 by the filtration type dust collector 6, slaked lime is added to the exhaust gas G14 from which the fine powder F has been removed by the slaked lime addition device 23, and chlorine, SOx, etc. are added by the filtration type dust collector 8. In the exhaust gas G15 from which the acidic component A has been removed, SOx, NOx, mercury, dioxins and the like are removed by the active coke tower 24, and the exhaust gas G16 of the active coke tower 24 is released from the chimney 13 to the atmosphere. .

  However, since the exhaust gas treatment device 21 cools the entire amount of the exhaust gas G11 of the cement kiln 2, a large amount of heat energy is lost. Further, desulfurization by addition of slaked lime is not efficient, and desulfurization is also performed in the activated coke tower 24. Furthermore, the operating cost of the active coke in the active coke tower 24 is high, and it cannot be said that dust generated by the regeneration of the active coke is discharged from the chimney or there is no possibility of dust explosion, and there is room for improvement.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and an object of the present invention is to treat cement kiln exhaust gas efficiently and at low cost while effectively using the thermal energy of the exhaust gas of the eco cement kiln. And

  In order to achieve the above object, the present invention is a cement kiln exhaust gas treatment device, a heat recovery device for recovering heat from exhaust gas of an eco-cement kiln, an activated carbon addition device for adding activated carbon to the exhaust gas of the heat recovery device, A dust collector that collects the exhaust gas to which the activated carbon is added, a reheating device that reheats the exhaust gas of the dust collector, a catalyst device that removes harmful substances in the reheated exhaust gas, and the catalyst And a wet dust collector that wet-collects exhaust gas from the apparatus. The activated carbon includes used activated carbon in addition to unused activated carbon.

  According to the present invention, a catalytic device that decomposes dioxins contained in exhaust gas and accelerates a mercury chloride production reaction between mercury and hydrogen chloride, and dissolves water-soluble mercury chloride contained in the exhaust gas of the catalyst device. By providing an activated carbon addition device that adds activated carbon that adsorbs dioxins and mercury in the exhaust gas before the wet dust collector to be removed, the concentration of mercury in the exhaust gas of the eco-cement kiln can be increased, Even if dioxins are re-synthesized in the previous stage, harmful substances such as mercury and dioxins can be more reliably removed by the catalyst device and the wet dust collector. Moreover, a catalyst apparatus and a wet dust collector can be reduced in size.

  Further, the heat recovery device can recover heat up to a temperature suitable for introducing the eco-cement kiln exhaust gas at about 800 ° C. into the catalyst device, and can effectively use the heat in the eco-cement kiln exhaust gas.

  In the cement kiln exhaust gas treatment apparatus, the reheating apparatus can perform the reheating using heat recovered by the heat recovery apparatus. Thereby, the exhaust gas of the heat recovery device can be reheated without a separate heat source.

  A second dust collecting device for collecting the exhaust gas of the heat recovery device, wherein the activated carbon adding device can add the activated carbon to the exhaust gas of the second dust collecting device; A dust device can collect dust having a high salt concentration such as sodium chloride and potassium chloride.

  The exhaust gas of the heat recovery device can be separated into a coarse powder and a gas containing fine powder, and a classification device that supplies the gas containing the fine powder to the second dust collector can be provided. While separating a high fine powder and making it a process target, the coarse powder with a low salt concentration can be utilized as a cement raw material.

  Furthermore, the present invention is a cement kiln exhaust gas treatment method, wherein heat recovery is performed from an exhaust gas from an eco-cement kiln, the temperature of the exhaust gas is lowered to 200 ° C. or less, activated carbon is added to the exhaust gas recovered, and the activated carbon Exhaust gas after collecting the dust, reheating the exhaust gas after dust collection to 350 ° C. or higher, removing harmful substances in the reheated exhaust gas using a catalyst, and removing the harmful substances Is characterized by wet-type dust collection.

  According to the present invention, as in the above invention, the catalyst decomposes dioxins contained in the exhaust gas and promotes the formation reaction of mercury chloride by mercury and hydrogen chloride, and dissolves the generated water-soluble mercury chloride. Before removal, dioxins and mercury in the exhaust gas are adsorbed and removed by activated carbon, increasing the concentration of mercury in the exhaust gas of the eco-cement kiln and causing re-synthesis of dioxins before treatment with the catalyst. However, harmful substances such as mercury and dioxins can be more reliably removed by the catalyst and wet dust collection. In addition, the amount of catalyst used can be kept low.

  Moreover, by regenerating the exhaust gas of an eco-cement kiln at about 800 ° C. to 200 ° C. or less by heat recovery, re-synthesis of dioxins is prevented, and by reheating the exhaust gas recovered to 350 ° C. or more, Prevents SOx and ammonia from reacting to form ammonium sulfate and resynthesis of dioxins in exhaust gas, avoids catalyst deactivation by ammonium sulfate, and more reliably removes harmful substances such as dioxins be able to.

  As described above, according to the present invention, the cement kiln exhaust gas can be processed efficiently and at low cost while effectively using the thermal energy of the eco cement kiln exhaust gas.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows one Embodiment of the processing apparatus of the cement kiln exhaust gas which concerns on this invention. It is a whole block diagram which shows an example of the processing apparatus of the conventional cement kiln exhaust gas.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an embodiment of a cement kiln exhaust gas treatment apparatus according to the present invention. This treatment apparatus 1 is attached to an eco-cement manufacturing apparatus including a cement kiln 2, a clinker cooler 3, and the like, and exhaust gas from the cement kiln 2 is shown. A boiler (heat recovery device) 4 for recovering heat from G1, a cyclone 5 as a classification device for separating the exhaust gas G2 of the boiler 4 into coarse powder C and exhaust gas G3 containing fine powder, and fine powder F from the exhaust gas G3 of the cyclone 5 And a filtration type dust collecting device 6 for removing water.

  Further, the treatment apparatus 1 includes an activated carbon addition apparatus 7 that adds activated carbon AC1 to the exhaust gas G4 of the filtration dust collector 6, and a filtration dust collection that collects the exhaust gas G5 to which the activated carbon AC1 is added by the activated carbon addition apparatus 7. Heat recovery from the exhaust gas G8 of the catalyst device 10, the reheating device 9 that reheats the exhaust gas G6 of the filtration dust collector 8, the catalyst device 10 that removes harmful substances from the exhaust gas G7 of the reheating device 9, A heat recovery device (second heat recovery device) 11, a wet scrubber 12 that wet-collects exhaust gas G 9 of the heat recovery device 11, a chimney 13 that releases exhaust gas G 10 of the wet scrubber 12 to the atmosphere, and a wet scrubber 12 The solid-liquid separation apparatus 14 which isolate | separates the slurry S discharged | emitted from the cake into the cake CA and the filtrate L, and the waste water treatment apparatus 15 which drains the filtrate L are provided.

  The boiler 4 is provided for recovering heat from the exhaust gas G1 of the cement kiln 2 to generate steam ST1 and using the generated steam ST1 in the reheating device 9. The boiler 4 has an ability to rapidly cool the exhaust gas G1 at about 800 ° C. to 200 ° C. or less. The generated steam ST1 can also be used in devices other than the reheating device 9.

  The cyclone 5 is provided for separating the exhaust gas G2 of the boiler 4 into a coarse powder C having a relatively low chlorine concentration and an exhaust gas G3 containing a fine powder having a high chlorine concentration, and a classification device other than the cyclone can also be used.

  The filtration type dust collector 6 is provided for recovering fine powder F having a high salt concentration such as sodium chloride and potassium chloride from the exhaust gas G3. For example, a bag filter can be used. A dust collector other than the filtration dust collector can also be used.

  The activated carbon addition device 7 is provided to add the activated carbon AC1 to the exhaust gas G4 of the filtration dust collector 6, and to adsorb and remove mercury and dioxins in the exhaust gas G4 on the activated carbon AC1.

  The filtration type dust collector 8 is provided for recovering the activated carbon AC2 that adsorbs mercury and dioxins, and for example, a bag filter can be used. A dust collector other than the filtration dust collector can also be used.

  The reheating device 9 is provided to reheat the exhaust gas G6 of the filtration dust collector 8 with the steam ST1 from the boiler 4, and returns the steam ST2 whose temperature has decreased after use to the boiler 4.

  The catalyst device 10 is provided to remove harmful substances such as NOx and dioxins contained in the exhaust gas G7 of the reheating device 9, and a titanium / vanadium-based denitration catalyst or the like can be used.

  The heat recovery device 11 is provided to recover heat from the exhaust gas G8 of the catalyst device 10 and reduce the temperature of the exhaust gas G8 to a temperature suitable for introduction into the wet scrubber 12. The heat recovery apparatus 10 can be a gas gas heater that performs heat exchange between the exhaust gas G8 and the exhaust gas G10, but may perform heat exchange between the exhaust gas G8 and a place other than the exhaust gas G10. Moreover, you may use heat exchangers other than a gas gas heater. Further, a cooling device for cooling the exhaust gas G8 can be used instead of the heat recovery device 10.

  The wet scrubber 12 as a wet dust collector is provided for cleaning the exhaust gas G9 of the heat recovery device 11, and water-soluble mercury chloride generated by promoting the reaction between mercury and hydrogen chloride in the catalyst device 10 is obtained. It takes in the slurry S which circulates and discharges.

  The solid-liquid separator 14 is provided for solid-liquid separation of the slurry S discharged from the wet scrubber 12, and a filter press, a belt filter, or the like can be used.

  The waste water treatment device 15 is provided for performing waste water treatment by adding a sulfurizing agent or a chelating agent to the filtrate L.

  Next, a cement kiln exhaust gas treatment method using the treatment apparatus 1 having the above configuration will be described with reference to FIG.

  Incineration ash of municipal waste and sewage sludge and cement raw material are supplied to the kiln bottom of the cement kiln 2 and the cement clinker is fired at about 1400 ° C. The fired cement clinker is cooled by a clinker cooler 3, and the obtained eco cement clinker is pulverized with gypsum and the like in a finishing mill (not shown) to produce eco cement.

  On the other hand, the exhaust gas G1 of about 800 ° C. from the cement kiln 2 is supplied to the boiler 4 and heat is recovered from the exhaust gas G1 so that the temperature of the exhaust gas G2 of the boiler 4 is 200 ° C. or less. By rapidly cooling the exhaust gas G1 to 200 ° C. or less, resynthesis of dioxins can be prevented.

  The exhaust gas G2 is classified by the cyclone 5 to separate the coarse powder C and returned to the cement kiln 2 to be used as a cement raw material. The exhaust gas G3 containing fine powder separated by the cyclone 5 is introduced into the filtration dust collector 6.

  Next, fine powder F containing a large amount of salt such as sodium chloride and potassium chloride contained in the exhaust gas G3 of the cyclone 5 is collected by the filtration dust collector 6, and the activated carbon addition device 7 is used to remove the fine powder F into the exhaust gas G4. Activated carbon AC1 is added, exhaust gas G5 to which activated carbon AC1 is added is collected by filtration dust collector 8, and activated carbon AC2 that adsorbs mercury and dioxins is recovered. Further, the exhaust gas G6 of the filtration dust collector 8 is introduced into the reheating device 9, and the exhaust gas G6 is reheated to 350 ° C. or higher by using the steam ST1 of the boiler 4 by the reheating device 9.

Here, the activated carbon AC1 added by the activated carbon addition device 7 can be used regardless of whether or not it contains a halogen element, but by using the contained one, the adsorption efficiency of mercury can be improved. Can do. Moreover, it is preferable that the addition amount of activated carbon AC1 shall be 10-40 mg / Nm < ³ > in an activated carbon basic unit, and, thereby, dioxins and mercury can be adsorbed and removed effectively.

  By heating the exhaust gas G6 to 350 ° C. or higher, SOx in the exhaust gas G6 reacts with ammonia to produce ammonium sulfate, and dioxins in the exhaust gas G6 are prevented from being re-synthesized. While avoiding life, harmful substances such as dioxins can be more reliably removed.

The reheated exhaust gas G7 is supplied to the catalyst device 10 to remove harmful substances such as NOx and dioxins in the exhaust gas G7. In the catalyst device 10, NOx was changed to N _2, to decompose the dioxins, mercury is reacted with hydrogen chloride in the exhaust gas G7 to water-soluble mercuric chloride.

  Next, the exhaust gas G8 of the catalyst device 10 is introduced into the heat recovery device 11 for heat recovery, the exhaust gas G9 after heat recovery is supplied to the wet scrubber 12, and mercury chloride is dissolved in the slurry S circulating in the wet scrubber 12. The exhaust gas G10 after removing harmful substances is discharged from the chimney 13 to the atmosphere.

On the other hand, the slurry S discharged from the wet scrubber 12 is supplied to the solid-liquid separator 14 and separated into cake CA and filtrate L, and the filtrate L containing mercury chloride is drained by the wastewater treatment device 15 and then discharged. Since the cake CA contains a large amount of gypsum (CaSO ₄ ), the cake CA can also be used as a cement raw material.

  As described above, according to the present embodiment, the catalyst device 10 that decomposes dioxins contained in the exhaust gas G7 and promotes the formation reaction of mercury chloride by mercury and hydrogen chloride, and the exhaust gas G9 of the heat recovery device 11 Eco-cement is provided with an activated carbon addition device 7 for adding activated carbon AC1 for adsorbing dioxins and mercury in the exhaust gas G4 in the previous stage with the wet scrubber 12 for dissolving and removing the water-soluble mercury chloride contained in Even if the concentration of mercury in the exhaust gas G1 of the kiln 2 increases or re-synthesis of dioxins occurs before the catalytic device 10, harmful substances such as mercury and dioxins are more reliably removed by the catalytic device 10 and the wet scrubber 12. can do. Moreover, the catalyst apparatus 10 and the wet scrubber 12 can be reduced in size.

  Further, the boiler 4 can recover heat up to a temperature suitable for introducing the eco cement kiln exhaust gas G1 of about 800 ° C. into the catalyst device 10, and can effectively use the heat in the eco cement kiln exhaust gas G1.

  In this embodiment, the boiler 4 is used as the heat recovery device. However, heat recovery may be performed using other devices, and the fine powder F is removed from the exhaust gas G2 using the cyclone 5 or the filtration dust collector 6. The exhaust gas G2 can also be processed without being recovered.

  In addition, it is preferable to reheat the exhaust gas G6 using the heat recovered by the boiler 4 in the reheating device 9 because it is not necessary to provide a separate heat source. However, the heat recovered by the boiler 4 can be used for other purposes. The exhaust gas G6 can be reheated by using a heat source other than the boiler 4 in the heating device 9.

DESCRIPTION OF SYMBOLS 1 Cement kiln exhaust gas treatment equipment 2 Cement kiln 3 Clinker cooler 4 Boiler 5 Cyclone 6 Filter type dust collector 7 Activated carbon addition device 8 Filter type dust collector 9 Reheating device 10 Catalyst device 11 Heat recovery device 12 Wet scrubber 13 Chimney 14 Solid Liquid separator 15 Wastewater treatment equipment AC1, AC2 Activated carbon C Coarse powder CA Cake F Fine powder G1-G10 Exhaust gas L Filtrate S Slurry ST1, ST2 Steam

Claims (5)

A heat recovery device that recovers heat from the exhaust gas of the eco-cement kiln;
An activated carbon addition device for adding activated carbon to the exhaust gas of the heat recovery device;
A dust collector for collecting the exhaust gas to which the activated carbon is added;
A reheating device for reheating the exhaust gas of the dust collector;
A catalytic device for removing harmful substances in the reheated exhaust gas;
A cement kiln exhaust gas treatment apparatus comprising: a wet dust collection device for collecting wet exhaust gas of the catalyst device.   2. The cement kiln exhaust gas treatment apparatus according to claim 1, wherein the reheating device performs the reheating using heat recovered by the heat recovery device.   3. A second dust collector that collects the exhaust gas of the heat recovery device is provided, and the activated carbon addition device adds the activated carbon to the exhaust gas of the second dust collector. 3. The cement kiln exhaust gas treatment apparatus described in 1.   The exhaust gas of the said heat recovery apparatus is isolate | separated into coarse powder and the gas containing fine powder, The classification apparatus which supplies the gas containing this fine powder to a said 2nd dust collector is provided. Cement kiln exhaust gas treatment equipment. Recovering heat from the exhaust gas of the eco-cement kiln and lowering the temperature of the exhaust gas to 200 ° C. or lower,
Add activated carbon to the heat recovered exhaust gas,
Collecting the exhaust gas after adding the activated carbon,
Reheat the exhaust gas after the dust collection to 350 ° C. or higher,
Removing harmful substances in the reheated exhaust gas using a catalyst,
A cement kiln exhaust gas treatment method, wherein the exhaust gas from which the harmful substances have been removed is wet-collected.

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