JP2013111549A - Adsorbent for adsorbing organic chlorine compound in exhaust gas, and method for producing the same and method for using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbent capable of efficiently adsorbing and removing organic chlorine compounds, particularly dioxins, contained in exhaust gas at low cost, and to provide a method for producing the same and a method for using the same.SOLUTION: The adsorbent for adsorbing organic chlorine compounds in exhaust gas includes hydrophobic solid unburned carbon which is a porous carbonaceous particle and has a structure having a specific surface area of at least 30 m/g and a mesopore volume of at least 0.03 mL/g. In the method for producing the adsorbent, a raw material containing the hydrophobic solid unburned carbon is separated into hydrophobic materials contained in a nonpolar organic solvent side and hydrophilic materials contained in a water side by liquid-liquid extraction using the nonpolar organic solvent and water. The separated hydrophobic materials are treated with an inorganic acid, and thus the adsorbent including the hydrophobic solid unburned carbon is extracted. Organic chlorine compounds in exhaust gas can be adsorbed and removed by adding the adsorbent to the exhaust gas.

Description

  The present invention relates to an adsorbent that adsorbs organic chlorine compounds in exhaust gas, particularly dioxins, and a method for producing and using the same.

  In recent years, wastes such as fly ash, main ash, sludge, and slag have been used as a part of cement raw materials. Therefore, the cement kiln exhaust gas contains lipophilic substances such as dioxins contained in these wastes. Organochlorine compounds exist. This organochlorine compound circulates in the cement production equipment using kiln dust as a medium, part of which is decomposed at high temperatures, and most of the undecomposed organochlorine compound is contained in the cement production equipment using dust in the exhaust gas as a medium. Is circulating.

  However, a trace amount of organochlorine compounds and gaseous organochlorine compounds that are not adsorbed by dust are released into the atmosphere together with the exhaust gas. Therefore, it is desirable to further reduce the discharge amount of these organochlorine compounds.

  As a solution to this problem, attempts to produce carbides (activated carbon, etc.) that adsorb organochlorine compounds using dust in exhaust gas as a raw material have recently attracted attention. However, although it has become clear that relatively large pores (mesopores) are necessary to adsorb and remove organochlorine compounds, in order to produce a carbide having such a structure from waste, There is a problem that it is very expensive in terms of cost.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and efficiently adsorbs organic chlorine compounds in exhaust gas discharged from cement production equipment, particularly toxic dioxins, at low cost. It is an object of the present invention to provide an adsorbent that can be removed and a method for producing and using the same.

In order to achieve the above object, the present invention is an adsorbent that adsorbs an organic chlorine compound in exhaust gas, and is a porous carbonaceous particle having a specific surface area of 30 m ² / g or more and a mesopore pore volume. Is characterized by containing hydrophobic solid unburnt carbon having a structure of 0.03 mL / g or more.

  According to the present invention, lipophilic organic chlorine compounds such as dioxins can be efficiently captured by the hydrophobic solid unburnt carbon contained in the adsorbent, and the concentration of organic chlorine compounds in the exhaust gas can be reliably ensured. It becomes possible to reduce it.

  The present invention is a method for producing the adsorbent, wherein the raw material containing the hydrophobic solid unburnt carbon is subjected to liquid-liquid extraction using a nonpolar organic solvent and water, thereby bringing the nonpolar organic solvent into the nonpolar organic solvent side. It is separated into a hydrophobic substance contained and a hydrophilic substance contained on the water side, and the adsorbent containing hydrophobic solid unburnt carbon is extracted by treating the separated hydrophobic substance with an inorganic acid. To do. And according to this invention, the adsorbent which has the said characteristic can be manufactured at low cost.

  In addition, as the raw material containing the hydrophobic solid unburnt carbon, one or more of fly ash, bottom ash, oil coke, and oil coke combustion ash can be used.

  In the method for producing the adsorbent, the nonpolar organic solvent may be toluene, hexane, benzene, diethyl ether, ethyl acetate, chloroform, or methyl chloride. In addition, in the method for producing the adsorbent, the inorganic acid may be hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.

  Furthermore, the adsorbent can be added to the exhaust gas to adsorb and remove the organic chlorine compound in the exhaust gas. When this exhaust gas is cement kiln exhaust gas, the content of the hydrophobic solid unburnt carbon in the dust collected by the dust collector that collects dust contained in the cement kiln exhaust gas is 0.2 mass. % Or more.

  As a result, only by adding the adsorbent according to the present invention to the exhaust gas discharged from a cement manufacturing apparatus, etc., the organic chlorine compound can be efficiently adsorbed and removed from the exhaust gas, and can be discharged out of the system. Can be rendered harmless.

  In addition, by using the method of use according to the present invention, it is possible to diversify the methods for treating organic chlorine compounds that have been conventionally incinerated and detoxified, and the fuel required for combustion and its Since no large-scale equipment is required, the cost of the entire processing system can be reduced.

  As described above, according to the present invention, an adsorbent capable of efficiently adsorbing and removing organochlorine compounds, particularly dioxins, in exhaust gas discharged from a cement production apparatus, etc., at low cost, and a production method and It is possible to provide a method of using the same.

It is a flowchart for demonstrating the manufacturing method of the adsorbent which concerns on this invention. It is the schematic which shows one Embodiment of the usage method of the adsorbent which concerns on this invention. When the adsorbent according to the present invention is used to adsorb organochlorine compounds from cement kiln exhaust gas, the content of hydrophobic solid unburnt carbon in the dust collection dust and dioxins (DXNs) at the dust collector outlet It is a graph which shows the relationship with a density | concentration.

  First, the manufacturing method of the adsorbent according to the present invention will be described with reference to FIG.

  A raw material containing hydrophobic solid unburnt carbon such as fly ash, bottom ash, oil coke, oil coke combustion ash, and cement raw material is liquid-liquid extracted using a nonpolar organic solvent and water (step S1). By this liquid-liquid extraction, the hydrophobic substance contained in the raw material is separated to the nonpolar organic solvent side, and the hydrophilic substance is separated to the water side. Here, the nonpolar organic solvent refers to, for example, toluene, hexane, benzene, diethyl ether, ethyl acetate, chloroform, or methyl chloride.

In addition, the hydrophobic solid unburnt carbon in the present invention refers to porous carbonaceous particles that are produced from raw materials containing unburned carbon and have hydrophobic properties. In particular, in the present invention, the specific surface area by BET method is 30 m ² / g or more (preferably 50 m ² / g or more), and the pore volume of mesopores (2 to 50 nm) by BJH method is 0.03 mL / g or more ( Preferably it is 0.04 mL / g or more, more preferably 0.05 mL / g or more). By having the predetermined specific surface area and mesopores as described above, it is possible to efficiently adsorb organochlorine compounds, particularly dioxins having a molecular length of about 1.4 nm, which are highly toxic.

  In general, a combustion gas dust such as fly ash contains a carbon component called unburned carbon, which is divided into solid carbon and oil. The hydrophobic solid unburnt carbon in the present invention is efficiently separated and extracted from this solid carbon.

  Next, the component on the nonpolar organic solvent side after liquid-liquid extraction is collected, and the solid component containing the hydrophobic solid unburnt carbon and the liquid component that is the nonpolar organic solvent are subjected to solid-liquid separation (step S2).

  Thereafter, an inorganic acid such as hydrochloric acid is added to the separated solid component, and the carbon component-derived carbon component contained in the solid component is changed to carbon dioxide and removed (step S3).

  After the inorganic acid treatment, the solid-liquid separation is performed again (step S4), and drying (step S5) is performed. The main component is hydrophobic solid unburnt carbon that can adsorb the organic chlorine compound in the exhaust gas. An adsorbent is obtained.

The amount of hydrophobic solid unburned carbon contained in the raw material is determined by weighing the weight of the adsorbent (residue) obtained as described above, and obtaining the residual rate based on the initial raw material amount. Based on the fraction and the measured amount of carbon in the residue, it can be calculated using the following formula.
Hydrophobic solid unburnt carbon amount (mass%) = measured carbon amount in residue (mass%) × residue rate (mass%) / 100

  Table 1 shows a method for producing an adsorbent according to the present invention, and manufacturing hydrophobic solid unburnt carbon from five kinds of raw materials containing unburned carbon, and measuring the specific surface area and the pore volume of mesopores. The results are shown. Here, the raw material A is a cement raw material, the raw materials B, C, and E are fly ash, and the raw material D is oil coke combustion ash.

  The specific surface area and mesopore pore volume were measured using Shimadzu Micromeritics ASP-2400 (manufactured by Shimadzu Corporation).

  From the results shown in Table 1, by using the adsorbent manufacturing method according to the present invention, it is possible to use, as a raw material, industrial waste such as fly ash, which has a problem with disposal, as a raw material. It turns out that the adsorbent which consists of hydrophobic solid unburnt carbon more than a reference | standard can be manufactured.

  Next, a method for using the adsorbent according to the present invention will be described with reference to FIGS. In the following description, the case where the organic chlorine compound contained in the cement kiln exhaust gas is adsorbed and removed by the adsorbent according to the present invention will be described as an example.

  FIG. 2 shows a cement kiln exhaust gas treatment system 1 using an adsorbent according to the present invention. This treatment system 1 is attached to a cement firing apparatus including a cement kiln 2, a preheater 3 and a calcining furnace 5, and is roughly classified to adsorbent A added to the exhaust gas G2 from the preheater 3 that has passed through a boiler 6 or the like. The material addition device 7, the dust collection device 8 that collects the dust and the adsorbent A contained in the exhaust gas G 2, and the collected dust (including the adsorbent A adsorbing the organic chlorine compound) D are removed from the cement kiln 2. It consists of a transport route 9 that is put into the kiln bottom 4.

  The cement kiln 2, the preheater 3, and the calcining furnace 5 are generally used in cement manufacturing apparatuses, and detailed descriptions thereof are omitted. Moreover, the dust collector 8 may be an electric dust collector or a bag filter generally used in a cement manufacturing apparatus, or may be a dust collector made of other methods. However, if the temperature in the dust collector is high, the adsorbed organochlorine compound is desorbed, so the internal temperature of the dust collector 8 needs to be maintained at 120 ° C. or lower.

  Boilers 6 and the like are for generating waste heat power generation using exhaust gas G1, a stabilizer (humidity control tower) for adjusting temperature and humidity of exhaust gas G1, and for generating cement raw material R to be supplied to preheater 3. Raw material equipment such as dryers and mills.

  It is preferable that the adsorbent addition device 7 inputs the adsorbent A immediately before the dust collector 8, for example, from the inlet duct 8 a of the dust collector 8. This is because the exhaust gas G1 passes through the boiler 6 or the like, so that the temperature drops to 300 ° C. or less, and a part of the organic chlorine compound in the exhaust gas G2 is generated and re-synthesized. This is because the organic chlorine compound can be more effectively adsorbed.

  The transport route 9 is provided for introducing the dust D including the adsorbent A adsorbing the organic chlorine compound into the kiln bottom 4 of the cement kiln 2.

  Next, operation | movement of the cement kiln exhaust gas processing system 1 which has the said structure is demonstrated.

  During the operation of the cement kiln 2, the cement raw material R supplied to the preheater 3 is preheated by the preheater 3, calcined in the calcining furnace 5, and then calcined in the cement kiln 2 to generate cement clinker. On the other hand, the exhaust gas discharged from the cement kiln 2 is discharged from the preheater 3 through the kiln bottom 4 and the calcining furnace 5 of the cement kiln 2, and the exhaust gas G1 from the preheater is collected via a fan or the like (not shown). 8 is introduced.

  When the organic chlorine compound concentration of the exhaust gas G1 is equal to or higher than a predetermined value, the gas adsorbent A is added to the exhaust gas G1 by the gas adsorbent addition device 7 to adsorb the organic chlorine compound. Next, the organochlorine compound in the dust D is burned by returning the dust D collected by the dust collector 8 directly to the kiln bottom 4 at 900 to 1000 ° C. in the cement kiln 2 directly via the transport route 9. Decompose. Thereby, the organochlorine compound density | concentration of the waste gas G1 from a cement manufacturing apparatus can be reduced. Here, since part of the gas adsorbent A contained in the dust D put into the kiln bottom 4 is combusted, the gas adsorbent A is further added to the exhaust gas G2 by the gas adsorbent addition device 7.

  FIG. 3 is a graph showing the relationship between the hydrophobic solid unburned carbon content of the dust collection dust D collected by the dust collection device 8 and the concentration of dioxins in the exhaust gas G3 of the dust collection device 8.

As is clear from this graph, as the amount of hydrophobic solid unburned carbon in the dust collection D collected by the dust collection device 8 increases, the concentration of dioxins in the exhaust gas G3 of the dust collection device 8 decreases. It can be seen that it has a negative correlation. Then, the gas adsorbent adding device 7 to the inlet duct of the dust collecting device 8 and the like so that the dust collection dust D collected by the dust collecting device 8 contains 0.2% by mass or more of the hydrophobic solid unburned carbon. By introducing the adsorbent A, the concentration of dioxins in the exhaust gas G3 can be reduced to an environmental standard of 0.1 ng-TEQ / m ³ N or less.

  In addition, in the said embodiment, although the case where the adsorbent which concerns on this invention was used for the waste gas of cement kiln was demonstrated, it is contained in the gas discharged | emitted from other baking apparatuses etc. besides the waste gas of cement kiln. It can also be used to adsorb and remove organochlorine compounds.

DESCRIPTION OF SYMBOLS 1 Cement kiln exhaust gas treatment system 2 Cement kiln 3 Preheater 4 Kiln bottom 5 Calciner 6 Boiler etc. 7 Adsorbent addition device 8 Dust collector 8a Inlet duct 9 Transport route A Adsorbent D Dust G1-G3 Exhaust gas R Cement raw material

Claims (7)

Porous carbonaceous particles comprising hydrophobic solid unburned carbon having a specific surface area of 30 m ² / g or more and mesopore pore volume of 0.03 mL / g or more Adsorbent that adsorbs organic chlorine compounds in exhaust gas. It is a manufacturing method of the adsorbent of Claim 1, Comprising: The raw material containing the said hydrophobic solid unburnt carbon is included in this nonpolar organic solvent side by liquid-liquid extraction using a nonpolar organic solvent and water. Separated into a hydrophobic substance and a hydrophilic substance contained in the water side,
A method for producing an adsorbent that adsorbs an organic chlorine compound in exhaust gas, wherein the adsorbent containing hydrophobic solid unburnt carbon is extracted by treating the separated hydrophobic substance with an inorganic acid.   The raw material containing the hydrophobic solid unburnt carbon is one or more of fly ash, bottom ash, oil coke, and oil coke combustion ash, according to claim 2. A method for producing an adsorbent that adsorbs an organic chlorine compound in exhaust gas.   The adsorbent for adsorbing organochlorine compounds in exhaust gas according to claim 2 or 3, wherein the nonpolar organic solvent is toluene, hexane, benzene, diethyl ether, ethyl acetate, chloroform, or methyl chloride Manufacturing method.   The method for producing an adsorbent for adsorbing an organic chlorine compound in exhaust gas according to claim 2 or 3, wherein the inorganic acid is hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid.   A method for using an adsorbent for adsorbing an organic chlorine compound in exhaust gas, comprising adding the adsorbent according to claim 1 to exhaust gas to adsorb and remove the organic chlorine compound in the exhaust gas.   The exhaust gas is a cement kiln exhaust gas, and the content of the hydrophobic solid unburnt carbon in the dust collected by a dust collector that collects dust contained in the cement kiln exhaust gas is 0.2% by mass or more. The method of using an adsorbent for adsorbing an organic chlorine compound in a cement kiln exhaust gas according to claim 6.

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