JP2017057122A - Apparatus and method for treating cement kiln exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently treat cement kiln exhaust gas at a low cost while effectively utilizing the thermal energy of eco-cement kiln exhaust gas.SOLUTION: A cement kiln exhaust gas treatment apparatus 1 comprises: a heat recovery device (boiler) 4 for recovering heat from exhaust gas G1 of an eco-cement kiln 2; a high-temperature dust collector (high-temperature bag filter) 6 that collects exhaust gas G2 of the heat recovery device 4 and has heat resistance of at least 350°C or higher; a catalyst device 7 for removing harmful substances in exhaust gas G4 of the high-temperature dust collector 6; a calcium-based agent adding device 8 for adding a calcium-based agent to exhaust gas G5 of the catalyst device 7; and a dust collector (high-temperature bag filter) 9 for collecting exhaust gas G6 to which the calcium-based agent has been added. The cement kiln exhaust gas treatment apparatus 1 may include an activated carbon adding device 11 for adding activated carbon AC to exhaust gas G8 of the dust collector 9, and a second dust collector (wet type scrubber) 12 for collecting exhaust gas G9 to which the activated carbon AC has been added.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.

  Further, in order to remove harmful substances derived from chlorine and heavy metals contained in incineration ash from the exhaust gas G12 of the exhaust gas cooling facility 22, the exhaust gas G12 is converted into coarse powder C and exhaust gas G13 containing fine powder by the cyclone 5. Separating and removing fine powder F from the exhaust gas G13 with the filtration dust collector 23, adding slaked lime with the slaked lime addition device 24 to the exhaust gas G14 from which the fine powder F has been removed, and using the filtration dust collector 25 with chlorine, SOx, The acidic component A is removed, SOx, NOx, mercury, dioxins and the like are removed from the exhaust gas G15 from which the acidic component A has been removed by the active coke tower 26, and the exhaust gas G16 of the active coke tower 26 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 26. Further, the operating cost of the activated coke in the activated coke tower 26 is high, and it cannot be said that dust generated by the regeneration of activated coke is discharged from the chimney 13 or dust explosion is possible, and there is room for improvement.

  Therefore, the present invention has been made in view of the above problems in the prior art, and aims to treat cement kiln exhaust gas efficiently and at low cost while effectively using the thermal energy of the eco cement kiln exhaust gas. To do.

  To achieve the above object, the present invention provides a heat recovery device that recovers heat from exhaust gas from an eco-cement kiln, a high-temperature dust collector that collects the exhaust gas from the heat recovery device, and has heat resistance of at least 350 ° C. A catalyst device for removing harmful substances in the exhaust gas of the high-temperature dust collector, a calcium-based drug addition device for adding a calcium-based chemical to the exhaust gas of the catalyst device, and collecting the exhaust gas to which the calcium-based chemical is added And a dust collecting device.

  According to the present invention, the catalytic device removes harmful substances such as NOx and dioxins in the exhaust gas, promotes the formation reaction of mercury chloride by mercury and hydrogen chloride in the exhaust gas, Adding chemicals to adsorb mercury chloride to calcium chemicals, reacting SOx in exhaust gas with calcium chemicals to make gypsum, and collecting calcium chemicals and gypsum with a dust collector efficiently Cement kiln exhaust gas can be treated at low cost.

  In addition, by providing a high temperature dust collector having heat resistance of 350 ° C. or higher in the front stage of the catalyst device, high temperature exhaust gas is introduced into the catalyst device without reheating the exhaust gas with heat recovered by the heat recovery device, It is possible to activate the catalyst of the catalyst device and increase the concentration of the calcium-based drug and gypsum in the dust collected in the dust collector.

  The cement kiln exhaust gas treatment device can include an activated carbon addition device that adds activated carbon to the exhaust gas of the dust collector, and a second dust collector that collects the exhaust gas to which the activated carbon is added. Thereby, harmful substances such as mercury and dioxins in the exhaust gas can be more reliably removed. The activated carbon can be used as well as unused.

  Furthermore, the second dust collector is a wet dust collector, and can include a solid-liquid separator that solid-liquid separates the slurry discharged from the wet dust collector. As a result, the activated carbon that has adsorbed the toxic substances is washed in the wet dust collector to desorb the toxic substances, and the activated carbon after desorption of the toxic substances is discharged to the solid side by the solid-liquid separator. It can be reused in activated carbon addition equipment and other equipment.

  Moreover, the classification | category apparatus which isolate | separates the waste gas of the said heat | fever recovery apparatus into coarse powder and the gas containing fine powder, and supplies the gas containing this fine powder to the said high temperature dust collector can be provided.

  Furthermore, the present invention is a cement kiln exhaust gas treatment method, wherein heat is recovered from exhaust gas from an eco-cement kiln, the exhaust gas at 350 ° C. or higher collected by heat recovery is collected, and harmful substances in the exhaust gas after the dust collection are collected. It is characterized by adding a calcium-based chemical to exhaust gas from which the harmful substances have been removed by using a catalyst, and collecting the exhaust gas to which the calcium-based chemical has been added.

  According to the present invention, similarly to the above-described invention, the catalyst removes harmful substances such as NOx and dioxins in the exhaust gas, and promotes the formation reaction of mercury chloride by mercury and hydrogen chloride in the exhaust gas, thereby performing catalyst treatment. Add calcium-based chemical to later exhaust gas to adsorb mercury chloride to calcium-based chemical, react SOx in exhaust gas with calcium-based chemical to form gypsum, and collect calcium-based chemical and gypsum by collecting dust Thus, the cement kiln exhaust gas can be treated efficiently and at low cost.

  In addition, by collecting the exhaust gas at 350 ° C or higher, the exhaust gas is not heated again by the recovered heat, etc., and the high temperature exhaust gas is catalyzed to activate the catalyst and collect the exhaust gas to which the calcium chemical is added. Thus, the concentration of the calcium-based drug and gypsum in the dust obtained can be improved.

  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. Boiler 4 that recovers heat from G1, cyclone 5 that separates exhaust gas G2 from boiler 4 into coarse powder C and exhaust gas G3 that contains fine powder, high-temperature bag filter 6 that collects exhaust gas G3 from cyclone 5, and high-temperature bug A catalyst device 7 for removing harmful substances from the exhaust gas G4 of the filter 6, a Ca-based drug addition device 8 for adding a calcium-based drug (hereinafter referred to as "Ca-based drug") to the exhaust gas G5 of the catalyst device 7, and a Ca-based drug A high-temperature bag filter 9 for collecting the exhaust gas G6 to which the Ca-based chemical is added from the addition device 8;

  The processing apparatus 1 includes a heat recovery device 10 that recovers heat from the exhaust gas G7 of the high-temperature bag filter 9, an activated carbon addition device 11 that adds activated carbon AC to the exhaust gas G8 of the heat recovery device 10, and an exhaust gas to which activated carbon AC is added. A wet scrubber 12 that wet-collects G9, a chimney 13 that discharges exhaust gas G10 of the wet scrubber 12 to the atmosphere, and a solid-liquid separator 14 that separates the slurry S discharged from the wet scrubber 12 into cake CA and filtrate L And a waste water treatment device 15 for waste water treatment of the filtrate L.

  The boiler 4 is provided to recover heat from the exhaust gas G1 of the cement kiln 2. The boiler 4 has an ability to rapidly cool the exhaust gas G1 at about 800 ° C. to 400 ° C. or less. The generated steam can be used in eco-cement manufacturing equipment and other equipment.

  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 high temperature bag filter 6 is provided for collecting the fine powder F in the exhaust gas G3. As this high-temperature bag filter 6, one having a heat resistance up to about 900 ° C. and including a filter made of a plurality of rod-shaped ceramic tubes can be used. In addition, a device other than the high-temperature bag filter can be used as long as it is a high-temperature dust collector having heat resistance of at least 350 ° C.

  The catalyst device 7 is provided for removing harmful substances such as NOx and dioxins contained in the exhaust gas G4 of the high-temperature bag filter 6 and for promoting the production reaction of mercury chloride by mercury and hydrogen chloride in the exhaust gas G4. Further, a titanium / vanadium-based denitration catalyst or the like can be used.

The Ca-based chemical addition device 8 adds a Ca-based chemical to the exhaust gas G5 of the catalyst device 7, adsorbs mercury chloride in the exhaust gas G5, and reacts SOx contained in the exhaust gas G5 with the Ca-based chemical to produce gypsum (CaSO ₄ ) Provided to be in.

  The high-temperature bag filter 9 is provided for collecting the gypsum and the Ca-based chemical adsorbing mercury chloride by collecting the exhaust gas G6 to which the Ca-based chemical is added. Note that a high-temperature dust collector other than the high-temperature bag filter 9 can be used, and a dust collector other than the high-temperature dust collector can also be used.

  The heat recovery device 10 is provided for recovering heat from the exhaust gas G7 of the high-temperature bag filter 9 and reducing the temperature of the exhaust gas G7 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 G7 and the exhaust gas G10, but may also perform heat exchange between a location other than the exhaust gas G7 and 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 G7 can be used instead of the heat recovery device 10.

The activated carbon addition device 11 is provided for adding activated carbon AC to the exhaust gas G8 of the heat recovery device 10 and adsorbing harmful substances such as mercury and dioxins that could not be removed by the catalyst device 7 and the high-temperature bag filter 9. Activated carbon AC can be used regardless of whether or not it contains a halogen group element. However, by using the activated carbon AC, the mercury adsorption efficiency can be improved. Moreover, it is preferable that the addition amount of activated carbon AC shall be 10-40 mg / Nm < ³ > in an activated carbon basic unit, and thereby dioxins and mercury can be adsorbed and removed effectively.

  The wet scrubber 12 is provided to wet-collect the exhaust gas G9 to which the activated carbon AC is added, separate it into the exhaust gas G10 and the slurry S, and discharge it. A wet dust collector other than the wet scrubber can be used, and a dust collector other than the wet dust collector can also be used.

  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. Further, the waste water treatment device 15 is provided for performing waste water treatment by adding a sulfiding 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.

  Cement clinker is fired by supplying incineration ash of municipal waste and sewage sludge and cement raw material to the kiln bottom of cement kiln 2. 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 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 350 ° C to 400 ° C.

  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 high-temperature bag filter 6 to collect the fine powder F. The exhaust gas G4 of the high-temperature bag filter 6 at about 350 ° C. is introduced into the catalyst device 7 to remove harmful substances such as NOx and dioxins in the exhaust gas G4, and mercury chloride is generated by mercury and hydrogen chloride in the exhaust gas G4. Promote the reaction.

  A Ca-based chemical containing slaked lime or the like is added from the Ca-based chemical addition device 8 to the exhaust gas G5 of the catalyst device 7 to cause the Ca-based chemical and SOx in the exhaust gas G5 to react to generate gypsum. Adsorb mercury chloride in G5. Here, since mercury chloride has the property of being easily adsorbed to Ca-based drugs, it can adsorb mercury efficiently.

  Further, the Ca-based chemical is such that Ca contained in the Ca-based chemical with respect to SOx in the exhaust gas G5 is 4.0 or less, preferably 1.5 to 2.0 in molar ratio. Thereby, Ca type | system | group chemical | medical agent and SOx in waste gas G5 can be made to react efficiently.

  Exhaust gas G6 to which a Ca-based chemical is added is introduced into the high-temperature bag filter 9, and the Ca-based chemical adsorbed with mercury chloride and gypsum are collected as dust D. The exhaust gas G7 of the high-temperature bag filter 9 is introduced into the heat recovery device 10 to recover heat, and activated carbon AC is added from the activated carbon addition device 11 to the exhaust gas G8 after the heat recovery, and harmful substances such as mercury and dioxins remaining in the exhaust gas G8 The substance is adsorbed on activated carbon AC.

  The exhaust gas G9 containing activated carbon adsorbing harmful substances is introduced into the wet scrubber 12, and separated into the exhaust gas G10 and the slurry S by wet dust collection. The exhaust gas 10 from which the activated carbon has been removed is discharged from the chimney 13 to the atmosphere, and the slurry S containing the activated carbon is solid-liquid separated into the cake CA and the filtrate L by the solid-liquid separator 14. Here, since the harmful substance adsorbed on the activated carbon is desorbed from the activated carbon in the wet scrubber 12, the activated carbon obtained from the cake CA is not adsorbed, and the activated carbon obtained from the cake CA is used as the activated carbon addition device 11 and others. Can be reused at any place. Further, the filtrate L is supplied to the waste water treatment device 15 for waste water treatment.

  As described above, according to the present embodiment, the catalytic device 7 removes harmful substances such as NOx and dioxins in the exhaust gas G4, and also generates mercury chloride by the mercury and hydrogen chloride in the exhaust gas G4. The Ca-based chemical is added to the exhaust gas G5 of the catalyst device 7 to adsorb mercury chloride to the Ca-based chemical, and SOx in the exhaust gas G5 reacts with the Ca-based chemical to form gypsum. Is recovered by the high-temperature bag filter 9, so that the cement kiln exhaust gas can be treated efficiently and at low cost.

  Moreover, by providing the high temperature bag filter 6 having a heat resistance of 350 ° C. or more in the front stage of the catalyst device 7, the high temperature exhaust gas G 4 is supplied to the catalyst device 7 without reheating the exhaust gas G 4 with heat recovered by the boiler 4. It can introduce and activate the catalyst of the catalyst apparatus 7, and can improve the density | concentration of Ca type | system | group chemical | medical agent and gypsum in the dust D collect | recovered in the high temperature bag filter 9. FIG.

  In this embodiment, the boiler 4 is used as the heat recovery device. However, heat recovery may be performed using another device, and the exhaust gas G2 is processed without using the cyclone 5 to recover fine powder from the exhaust gas G2. You can also

DESCRIPTION OF SYMBOLS 1 Cement kiln exhaust gas treatment apparatus 2 Cement kiln 3 Clinker cooler 4 Boiler 5 Cyclone 6 High temperature bag filter 7 Catalytic device 8 Ca system chemical | medical agent addition apparatus 9 High temperature bag filter 10 Heat recovery apparatus 11 Activated carbon addition apparatus 12 Wet scrubber 13 Chimney 14 Solid-liquid separation Device 15 Wastewater treatment device AC Activated carbon C Coarse powder Ca Ca-based chemical CA Cake D Dust F Fine powder G1 to G10 Exhaust gas L Filtrate S Slurry

Claims (5)

A heat recovery device that recovers heat from the exhaust gas of the eco-cement kiln;
A high-temperature dust collector that collects the exhaust gas of the heat recovery device and has heat resistance of at least 350 ° C.,
A catalyst device for removing harmful substances in the exhaust gas of the high-temperature dust collector;
A calcium-based drug addition device for adding a calcium-based drug to the exhaust gas of the catalyst device;
A cement kiln exhaust gas treatment apparatus comprising: a dust collector that collects the exhaust gas to which the calcium-based chemical is added. An activated carbon addition device for adding activated carbon to the exhaust gas of the dust collector;
The cement kiln exhaust gas treatment device according to claim 1, further comprising a second dust collector that collects the exhaust gas to which the activated carbon is added.   The said 2nd dust collector is a wet dust collector, Comprising: The solid-liquid separator which solid-liquid-separates the slurry discharged | emitted from this wet dust collector is characterized by the above-mentioned. Cement kiln exhaust gas treatment equipment.   The exhaust gas of the said heat recovery apparatus is isolate | separated into coarse powder and the gas containing fine powder, and the classification apparatus which supplies the gas containing this fine powder to the said high temperature dust collector is provided. The cement kiln exhaust gas treatment apparatus described in 1. Heat recovery from the exhaust gas from the eco-cement kiln,
Collecting the heat-recovered exhaust gas of 350 ° C. or higher,
Use a catalyst to remove harmful substances in the exhaust gas after the dust collection,
Add calcium-based chemicals to the exhaust gas from which the harmful substances have been removed,
A cement kiln exhaust gas treatment method, wherein the exhaust gas to which the calcium-based chemical is added is collected.

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