JP2007070173A - Method for lowering organochlorine compound in cement production equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for lowering organochlorine compounds in waste gases from cement production equipment, which method is capable of lowering emission of the organochlorine compounds such as dioxins and PCBs from the cement production equipment. <P>SOLUTION: The method for lowering the organochlorine compounds comprises, in the course of feeding waste gases from the top of a preheater 16 into a raw material grinding step section A, withdrawing part of the waste gases via a first waste gas branching pipe 150 and feeding it into that lower section of the preheater 16 which reaches 800°C or higher during the ordinary operation of the cement production equipment 10. Since the organochlorine compounds such as dioxins and PCBs contained in the waste gases are thus pyrolized, the emission of the organochlorine compounds from the cement production equipment 10 can be lower than in the conventional method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for reducing organochlorine compounds in a cement production facility, more specifically dioxins in a cement production facility and organochlorine compounds such as PCBs, so that the amount of organochlorine compounds discharged from the facility can be reduced. Regarding technology.

Dioxins (PCDDs) are abbreviations of poly chloro dibenzo-p-dioxin and are a kind of organic chlorine compounds. Poly chloro dibenzofuran (PCDFs) is known as an analog of this dioxin.
In particular, it belongs to Tetra chloro dibenzo-p-dioxin, which is a tetrachloride of PCDDs (T4CDDs), and has chlorine at positions 2, 3, 7, 8 3,7,8-T4CDD is highly toxic.
The 2,3,7,8-tetrachloro form is obtained as a by-product in the production of trichlorophenol, 2,4,5-trichlorophenoxyacetic acid, and is obtained by chlorination of dibenzo-P-dioxin. The melting point is 306-307 ° C.

  Further, as another organic chlorine compound that is harmful to the human body, for example, PCB (polychlorinated biphenyl) is known. PCB is excellent in chemical stability, insulation, nonflammability, and adhesiveness, and has been used as an insulating oil for transformers and capacitors mounted in electric facilities such as power plants, railways, and buildings. However, it contains a coplanar PCB that has the same toxicity as dioxin. Therefore, in 1974, the law prohibits the manufacture, distribution and new use of PCBs.

  Examples of the PCB treatment method include an incineration treatment method in which PCB is heat-treated at a high temperature, a dechlorination decomposition method in which PCB is dechlorinated, and a supercritical water in which PCB is decomposed into carbon dioxide and water. A critical hydrolytic decomposition method has been developed. Of these, incineration methods are concerned that dioxins are synthesized when the heat treatment gas of PCB is cooled.

Thus, for example, Patent Document 1 and Patent Document 2 are known as conventional techniques for solving these problems.
Patent Document 1 supplies exhaust gas from a cement production facility to a dust collector, collects dust collection dust containing an organic chlorine compound, and collects at least a part of the collected dust collection dust at 800 ° C. or higher in the cement production facility. This shows a method of putting it in the high temperature part. Since dioxins are thermally decomposed at around 800 ° C., this method can efficiently decompose and detoxify dioxins. Examples of the exhaust gas from the cement production facility include exhaust gas from a raw material dryer (raw material pulverization step) for drying cement raw materials, exhaust gas from a raw material mill (raw material pulverization step) for pulverizing cement raw materials.

  In addition, a small amount of vaporized organochlorine compound is also contained in the dedusted gas discharged from the dust collector and released to the atmosphere from the flue. As a countermeasure against this, Patent Document 1 describes a method of reducing the dioxin concentration in the dedusted gas. This is a method in which exhaust gas is drawn from a point (low temperature part) at a temperature of 30 to 400 ° C. in a cement manufacturing facility and supplied to a dust collector. That is, in the exhaust gas derived from the low temperature part, the organochlorine compound is concentrated (low temperature concentration) compared to the exhaust gas from the high temperature part of the cement manufacturing facility. As a result, the concentration of dioxins in the dedusted gas decreases if the dust collection dust having a high concentration of organic chlorine compound is removed by the dust collection process.

In Patent Document 2, a PCB-containing material carried from the outside to a cement factory is put into a rotary kiln, and this is heated by heat (1000 ° C. or higher) when a cement clinker is fired to thermally decompose the PCB. A method is shown in which exhaust gas generated during pyrolysis is led out of the rotary kiln and then rapidly cooled at a cooling rate of 20 ° C./second or more. By cooling the exhaust gas at 20 ° C./second or more, the exhaust gas passes through a temperature range in which the amount of dioxins synthesized increases in a short time. As a result, PCB can be decomposed while preventing vaporization of dioxins.
JP 2004-244308 A JP 2002-147722 A

  Thus, according to Patent Document 1, at least a part of the dust collected by passing the exhaust gas through the dust collector is put into a high temperature part of a cement manufacturing facility that is 800 ° C. or higher during normal operation, and the dust is collected. Dioxins adsorbed by dust were pyrolyzed. At that time, as a measure against organochlorine compounds in the dedusted gas (dust collector passing gas) released from the flue to the atmosphere, the exhaust gas is drawn out from the point where the temperature is 30 to 400 ° C. (low temperature part) in the cement production facility, The method of supplying this to a dust collector was adopted.

  However, with this measure, dioxins discharged from the cement production facility could not be reduced sufficiently. That is, the cement raw material containing the organic chlorine compound was put into a raw material dryer and a raw material mill each having an internal temperature of about 300 ° C. using exhaust gas discharged from the upper part of the preheater as a heat source. The amount of dioxins generated increases around 300 ° C. Therefore, a large amount of organochlorine compound was contained in the exhaust gas (particularly dust) from the raw material mill or the like.

  On the other hand, the cement raw material pulverized by the raw material mill is continuously fed into the upper part of the preheater. At this time, most of the organic chlorine compounds adhering to the cement raw material are not thermally decomposed as the cement raw material descends in the preheater, but are vaporized (separated) by the heat of the upper part of the preheater (including the heat of exhaust gas). It was mixed with the exhaust gas and returned to the raw material mill. As a result, organochlorine compounds were circulated in the raw material grinding process for cement production, and the concentration was gradually increased. Therefore, the amount of dioxins discharged from the cement manufacturing facility has increased.

  Patent Document 2 discloses that a PCB-containing material carried from outside (external) of a cement manufacturing facility is heated to 1000 ° C. or higher in a rotary kiln to be thermally decomposed. However, with this method, PCB evaporated in the cement production facility could not be removed.

  Therefore, as a result of earnest research, the inventor fractionated a part of the exhaust gas (including organochlorine compounds) generated during the firing of the cement clinker to the raw material pulverization process section, and operated it normally. If the chlorinated organic compounds are pyrolyzed by putting them in the high temperature part of the cement manufacturing facility, which is sometimes over 800 ° C, the amount of dioxins and PCBs released from the cement manufacturing facility will be reduced. The present invention was completed by finding out that it can be reduced.

  In addition, as a result of earnest research, the inventor fractionated a part of the cement raw material supplied to the upper part of the preheater, and the separated cement raw material was preheated to 800 ° C. or higher during normal operation of the cement production facility. If the organochlorine compound contained in the exhaust gas is pyrolyzed by introducing it into the lower part, the amount of dioxins and PCBs such as PCBs emitted from the cement production facility will be reduced compared to the conventional level. The present invention was completed by discovering that it can be reduced.

  An object of the present invention is to provide a method for reducing organochlorine compounds in a cement production facility that can reduce the amount of dioxins discharged from the cement production facility and organochlorine compounds such as PCB.

  The invention according to claim 1 is an organic chlorine compound reduction method in a cement manufacturing facility in which cement clinker is fired from the cement raw material dried and pulverized in the raw material pulverization process section, and cement is produced from the cement clinker. A heat source supply step for supplying exhaust gas containing a chlorine compound and generated during firing of the cement clinker as a heat source for drying the cement raw material to the raw material grinding step, and 800 ° C. during normal operation of the cement manufacturing facility The above-described high temperature part is provided with a decomposition step of separating and charging a part of the exhaust gas supplied to the raw material pulverization process part and thermally decomposing the organic chlorine compound contained in the exhaust gas This is a method for reducing organochlorine compounds in a cement manufacturing facility.

  According to the first aspect of the present invention, a part of the exhaust gas is collected while supplying the exhaust gas generated at the time of firing the cement clinker to the raw material grinding step. Thereafter, the collected exhaust gas is put into a high temperature portion in a cement manufacturing facility that is 800 ° C. or higher during normal operation. Thereby, the organic chlorine compound contained in exhaust gas is decomposed | disassembled by the heat | fever of a high temperature part. As a result, the circulation of the organic chlorine compound in the raw material pulverization process of cement production is interrupted, and the concentration of the organic chlorine compound is suppressed. Therefore, the amount of dioxins discharged from the cement production facility and the amount of organochlorine compounds such as PCB can be reduced as compared with the conventional case.

Organochlorine compounds exist in the gas state of the exhaust gas in a vaporized state (gas) or adhere to the dust content of the exhaust gas.
The vaporization (separation) temperature of dioxins (including the precursor) is 100 to 800 ° C. The decomposition temperature of dioxins is 800 ° C. or higher. Moreover, the vaporization (separation) separation temperature of PCB is 100-800 degreeC. The decomposition temperature of PCB is 800 ° C. or higher.

The cement production facility may be a rotary kiln having a preheater and a calciner. In this case, as a high temperature part of 800 ° C. or higher, for example, a lower part of the preheater (850 ° C.), a calcining furnace (850 ° C.), a kiln bottom part of a rotary kiln (1000 ° C.), a kiln front part (1450 ° C.), and a clinker cooler The high temperature part (800 degreeC or more) etc. are mentioned.
When the high temperature part is less than 800 ° C., for example, organic chlorine compounds such as dioxins cannot be completely thermally decomposed. The preferable temperature of the high temperature part is 850 ° C. or higher. Within this range, for example, organic chlorine compounds such as dioxins can be completely pyrolyzed.
As the raw material pulverizing step, for example, a raw material dryer for drying a cement raw material having a high water content such as clay and a raw material mill for pulverizing the cement raw material can be adopted.

As the exhaust gas, for example, when the cement manufacturing facility has a preheater and a rotary kiln, exhaust gas discharged from the upper part of the preheater during firing can be employed. Moreover, when the cement production facility has only a rotary kiln, exhaust gas discharged from the rotary kiln can be employed. However, it is not limited to these.
The temperature of the exhaust gas is usually 100 to 350 ° C.

  The fraction of exhaust gas is 5 to 10% of the total exhaust gas. If it is less than 5%, the organic chlorine compound cannot be decomposed efficiently. On the other hand, if it exceeds 10%, the effect on cement production is large due to energy loss.

  The invention according to claim 2 is characterized in that the exhaust gas is a gas discharged from the upper part of the preheater during firing of the cement clinker, and the high temperature part is a lower part of the preheater. It is an organic chlorine compound reduction method in the described cement manufacturing equipment.

  According to the second aspect of the present invention, a part of the exhaust gas discharged from the upper part of the preheater at the time of firing the cement clinker is fractionated, and the lower part of the preheater that becomes 800 ° C. or higher during normal operation of the cement manufacturing facility. It is thrown. Thereby, the organochlorine compound contained in the exhaust gas is decomposed by the heat of the lower part of the preheater. As a result, the amount of dioxins discharged from the cement manufacturing facility and the amount of organochlorine compounds such as PCB can be further reduced as compared with the conventional case.

  According to a third aspect of the present invention, the exhaust gas is a gas discharged from an upper portion of a preheater during firing of the cement clinker, and the high temperature portion is a charging portion of a cement clinker discharged from a rotary kiln in the clinker cooler. The method for reducing organochlorine compounds in a cement production facility according to claim 1, wherein the method is in the vicinity.

  According to the invention described in claim 3, the exhaust gas discharged from the upper part of the preheater at the time of cement clinker firing is partly collected, and the temperature of the clinker cooler becomes 800 ° C. or higher during normal operation of the cement manufacturing facility. In the vicinity of the cement clinker input from the rotary kiln. As a result, the organic chlorine compound contained in the exhaust gas is decomposed by the heat in the vicinity (upstream part) of the cement clinker charging part of the clinker cooler. As a result, the amount of dioxins discharged from the cement manufacturing facility and the amount of organochlorine compounds such as PCB can be further reduced as compared with the conventional case.

  According to a fourth aspect of the present invention, the upper part of the preheater and the raw material crushing process part are connected by an exhaust gas duct having a fan, and the exhaust gas is fractionated from a portion downstream of the fan in the exhaust gas duct. The method for reducing an organochlorine compound in a cement production facility according to claim 2 or claim 3, wherein

According to invention of Claim 4, waste gas is fractionated from the positive pressure area | region of a downstream part from a fan among exhaust gas ducts. On the other hand, among the lower stage part of the preheater which is the high temperature part of Claim 2 and the clinker cooler which is the high temperature part of Claim 3, the vicinity of the cement clinker charging part is a negative pressure region. Therefore, by simply connecting the corresponding ones with, for example, tubes, the separated exhaust gas is separated from the separated exhaust gas by the pressure difference between the two openings of each tube. Can be supplied respectively. Thereby, cost reduction of cement manufacturing equipment can be achieved.
The exhaust gas duct with a fan has a negative pressure region upstream of the fan. Further, the downstream portion from the fan is a positive pressure region.

  According to a fifth aspect of the present invention, a part of the cement raw material supplied to the upper portion of the preheater is separated, and the separated cement raw material is 800 ° C. or higher during normal operation of the cement manufacturing facility. A method for reducing organochlorine compounds in a cement production facility, comprising a decomposition step of thermally decomposing an organochlorine compound that is introduced into a lower part.

According to the fifth aspect of the present invention, a part of the cement raw material supplied to the upper part of the preheater is separated, and the separated cement raw material is preheated to 800 ° C. or higher during normal operation of the cement production facility. By putting it in the lower part, the organic chlorine compound is pyrolyzed. Thereby, the discharge | release amount of organochlorine compounds, such as dioxins and PCB which are discharged | emitted from a cement manufacturing facility, can be reduced more.
The amount of the cement raw material is not limited. For example, it is 10% of the cement raw material put into the preheater. If it exceeds 10%, the stability of the operation of the cement facility is affected.
In the cement manufacturing facility, the place where a part of the cement raw material supplied to the upper part of the preheater is separated is not limited. For example, it may be a storage silo in which the cement raw material pulverized by the raw material mill is stored, or it may be an intermediate part of the raw material powder transport facility for supplying the crushed cement raw material from the storage silo to the upper part of the preheater.

  The invention according to claim 6 is characterized in that the sorted cement raw material is discharged into the exhaust gas discharged from the upper part of the preheater and supplied to the lower stage of the preheater when the cement clinker is fired. The organochlorine compound reducing method in a cement manufacturing facility according to claim 5.

  According to the invention described in claim 6, since a part of the cement raw material supplied to the upper part of the preheater is separated, this is put into the exhaust gas that is being put into the lower part of the preheater. Moreover, the amount of dioxins and organic chlorine compounds such as PCBs discharged from the cement production facility can be further reduced.

  To put the sorted cement raw material into the exhaust gas in the middle of feeding the lower stage part of the preheater is, for example, the middle part of the exhaust gas feeding path connected to the lower stage part of the preheater, or the preheater and the feeding path. This sort of cement raw material is put into the connecting portion.

  According to the first aspect of the present invention, while supplying the exhaust gas generated at the time of firing the cement clinker to the raw material pulverization process part, a part of the exhaust gas is separated and becomes 800 ° C. or higher during normal operation. If the organic chlorine compounds in the exhaust gas are thermally decomposed by putting them in the high temperature part of the cement manufacturing facility, the amount of organic chlorine compounds such as dioxins and PCBs emitted from the cement manufacturing facility will be reduced. Can be reduced compared to

  Further, according to the invention described in claim 5, a part of the cement raw material supplied to the upper part of the preheater is separated, and the separated cement raw material becomes 800 ° C. or higher during normal operation of the cement manufacturing facility. If the chlorinated organic compounds are thermally decomposed by putting them in the lower part of the preheater, the amount of dioxins and PCBs chlorinated organic compounds emitted from cement production facilities will be reduced compared to the conventional one. Can do.

  In particular, according to the invention described in claim 6, since a part of the cement raw material being supplied to the upper part of the preheater is fractionated, this is put into the exhaust gas being put into the lower stage of the preheater. It is possible to further reduce the discharge amount of dioxins and organic chlorine compounds such as PCB discharged from the cement production facility.

  Examples of the present invention will be specifically described below.

  In FIG. 1, reference numeral 10 denotes a cement firing facility to which the organic chlorine compound reducing method in a cement manufacturing facility according to Embodiment 1 of the present invention is applied. The cement firing facility 10 includes a raw material grinding step A for grinding a cement raw material, and a firing step B for firing the ground cement raw material.

  The raw material pulverization process section A includes a raw material storage 11 for individually storing limestone, clay, silica and iron raw materials as cement raw materials, and a raw material dryer 12 for heating and drying cement raw materials having a high water content such as clay, A raw material mill 13 for pulverizing the cement raw material, an electrostatic precipitator 30 for collecting dust containing organic chlorine compounds discharged from the raw material dryer 12 and the raw material mill 13, and a storage for temporarily storing the cement raw material crushed by the raw material mill 13 And a silo 14.

  The cement raw material stored in the raw material storage 11 is put into the rotating drum of the raw material mill 13 through the raw material transporting equipment 118. However, a part of the cement raw material having a high water content is supplied to the raw material dryer 12 through the water-containing raw material supply facility 131. This part of the cement raw material is heated and dried here, and then fed into the raw material mill 13 containing a number of metal balls through the dry raw material discharge facility 132. The raw material dryer 12 and the raw material mill 13 are respectively supplied with high-temperature exhaust gas at 350 ° C. from an upper part of a preheater 16 described later through an exhaust gas duct 21 having a bifurcated downstream portion. Therefore, the internal temperature of the raw material dryer 12 is about 300 ° C., and the internal temperature of the raw material mill 13 is about 100 to 200 ° C. A fan F <b> 1 is provided upstream of the exhaust gas duct 21. By continuously feeding the cement raw material while rotating the rotating drum of the raw material mill 13, the cement raw material is pulverized to about 90 μm or less. The crushed cement raw material is input to the storage silo 14 through the pulverized raw material transport facility 121.

  The raw material dryer 12 and the raw material mill 13 are connected to each end portion of the upstream side portion of the flue 129 that opens the exhaust gas from the inside through the chimney 130 to the atmosphere. In the middle of the downstream side portion of the flue 129, the electric dust collector 30 is provided. Further, in the flue 129, a fan F2 is provided on the material mill 13 side on the upstream side which is a fork, and a fan F3 is provided in a portion between the electrostatic precipitator 30 and the chimney 130.

In the exhaust gas duct 21, a portion (positive pressure region) between the bifurcated branch portion and the fan F <b> 1 has a base portion of the first exhaust gas branch pipe 150 whose tip portion is connected to the lower stage portion of the preheater 16. It is connected. A valve 151 is provided in the middle of the first exhaust gas branch pipe 150. Further, in the first exhaust gas branch pipe 150, the tip portion is between the connection portion with the exhaust gas duct 21 and the valve 151, and in the vicinity of the input portion of the cement clinker discharged from the rotary kiln 18 in the clinker cooler 19. The base part of the 2nd exhaust gas branch pipe 152 connected with is connected. A valve 153 is provided in the middle of the second exhaust gas branch pipe 152.
In addition, the first exhaust gas branch pipe 150 includes a raw material sorting pipe 154 having a base portion connected to the storage silo 14 between the valve 151 and a connection portion with the lower stage portion (high temperature portion) of the preheater 16. You may connect a front-end | tip part. Thereby, a part of the cement raw material being supplied to the upper part of the preheater 16 can be supplied to the exhaust gas being supplied to the lower part of the preheater 16.

  The firing process section B includes a preheater 16 having a five-stage cyclone 15 that gradually heats the cement raw material from the storage silo 14 to a high temperature (850 ° C.) as it descends, and the bottom stage of the preheater 16 at the kiln bottom. Are connected to each other, and a dry rotary kiln 18 having a combustion burner 17 at the front of the kiln, a clinker cooler 19 for cooling the cement clinker discharged from the kiln of the rotary kiln 18 and the obtained cement clinker are temporarily stored. A clinker silo (not shown) and a second dust collector (not shown) that collects dust discharged from the clinker silo are provided.

The pre-heater 16 passes through the upper and lower cyclones 15 from the upper side in order so that the pulverized raw material charged from the storage silo 14 is easily fired in the rotary kiln 18 via the raw material powder transporting facility 165, while being sequentially passed through the predetermined temperature (800 Preheat to ~ 900 ° C.
A rotary kiln 18 that produces cement clinker at 100 t / h is employed. The rotary kiln 18 has a kiln shell lined with a refractory, and the cement clinker is fired from the cement raw material by the heat of the flame from the combustion burner 17 fueled with heavy oil or fine coal.

Next, the organic chlorine compound reduction method in the exhaust gas performed in the cement production facility 10 of Example 1 (inside the system) will be described. In advance, the valve 151 of the first exhaust gas branch pipe 150 is opened, and the valve 153 of the second exhaust gas branch pipe 152 is closed.
As shown in FIG. 1, each cement raw material in the raw material storage 11 is put into the raw material mill 13 through the raw material transport facility 118. However, only a part of the cement raw material having a high water content is supplied to the raw material dryer 12 through the water-containing raw material supply facility 131. This part of the cement raw material is heated and dried in the raw material dryer 12 and then fed into the raw material mill 13 through the dry raw material discharge facility 132. In the raw material mill 13, the cement raw material is pulverized to a particle size of approximately 90 μm or less together with the dry raw material from the raw material dryer 12 by a large number of metal balls. The pulverized cement raw material is fed into the storage silo 14 through the pulverized raw material transport facility 121.

  High temperature exhaust gas is supplied to the raw material dryer 12 and the raw material mill 13 from above the preheater 16 through the exhaust gas duct 21. Therefore, the internal temperature of the raw material dryer 12 is kept at about 300 ° C., and the internal temperature of the raw material mill 13 is kept at about 100 ° C., respectively. Since the insides of the raw material dryer 12 and the raw material mill 13 are heated to around 300 ° C., the organic chlorine compounds (mainly dioxins) may be concentrated inside these. The dust containing the organic chlorine compound thus concentrated passes through the flue 129 and is collected by the electric dust collector 30. The dust collection dust sequentially passes through the dust delivery pipe 123 and the pulverized raw material transport facility 121 and is supplied to the storage silo 14 together with the cement raw material from the raw material mill 13.

The cement raw material stored in the storage silo 14 is then supplied to the firing process part B. That is, the pulverized cement raw material is supplied to the upper part of the preheater 16 via the raw material powder transport facility 165. The pulverized raw material is heated (preheated) while descending each cyclone 15 in turn until the limestone in the cement raw material is decarboxylated. At this time, a part of the exhaust gas passing through the exhaust gas duct 21 is collected through the first exhaust gas branch pipe 150 and is put into the lower stage of the preheater 16. As a result, dioxins and organic chlorine compounds such as PCB in the collected exhaust gas are decomposed by the heat of the lower stage of the preheater 16 that becomes 800 ° C. or higher during normal operation. As a result, the circulation of the organic chlorine compound between the raw material crushing process part A and the upstream part of the baking process part B is cut off, and the increase in the concentration of the organic chlorine compound is suppressed. Therefore, the discharge amount of the organic chlorine compound discharged from the cement manufacturing facility 10 can be reduced as compared with the conventional case.
The obtained preheating raw material (cement raw material) is put into the kiln bottom of the rotary kiln 18 and is fired into a cement clinker by heating at 1100 to 1450 ° C. using a combustion burner 17 while rotating in the kiln shell. The cement clinker falls from the front end of the kiln to the clinker cooler 19 where it is cooled.

By the way, the exhaust gas duct 21 has the fan F1 as a branch point, the upstream portion thereof is a negative pressure region, and the downstream portion thereof is a positive pressure region. The base of the first exhaust gas branch pipe 150 is connected to the positive pressure region of the exhaust gas duct 21. Further, the lower part of the preheater 16 to which the tip of the first exhaust gas branch pipe 150 is connected is a negative pressure region. Further, the upstream portion of the clinker cooler 19 to which the tip of the second exhaust gas branch pipe 152 is connected (near the cement clinker charging portion) is also a negative pressure region.
Therefore, the exhaust gas in the exhaust gas duct 21 is reduced by the pressure difference between the opening portions at both ends of the first exhaust gas branch pipe 150 only by connecting the exhaust gas duct 21 and the lower stage portion of the preheater 16 to the first exhaust gas branch pipe 150. It can be supplied to the lower part of the preheater 16 without power.

  Further, the exhaust gas duct 21 and the clinker cooler 19 are simply connected by the upstream portion of the first exhaust gas branch pipe 150 and the second exhaust gas branch pipe 152, and the upstream opening of the first exhaust gas branch pipe 150, Due to the pressure difference from the downstream opening of the second exhaust gas branch pipe 152, the exhaust gas in the exhaust gas duct 21 is supplied without power to the vicinity of the cement clinker charging portion discharged from the rotary kiln 18 in the clinker cooler 19. be able to. Thereby, cost reduction of the cement manufacturing equipment 10 can be achieved. The separated exhaust gas may be supplied to both the preheater 16 and the clinker cooler 19 by opening the valves 151 and 153.

  Next, the preheated cement raw material is put into the kiln bottom of the rotary kiln 18. Here, the cement clinker is fired by the burner heating by the combustion burner 17 while the cement raw material is rotated in the circumferential direction along with the rotation of the kiln shell. The obtained cement clinker is cooled in the internal space of the clinker cooler 19. Thereafter, the cement clinker is put into a finishing clinker silo where it is stored.

  At this time, if the operation of closing the valve 151 and opening the valve 152 is performed, a part of the exhaust gas flowing through the exhaust gas duct 21 is discharged from the rotary kiln 18 in the clinker cooler 19 through the second exhaust gas branch pipe 152. It can be charged near the cement clinker charging part. As a result, dioxins and organic chlorine compounds such as PCB contained in the collected exhaust gas can be decomposed by heat (800 ° C. or higher) in the upstream portion of the clinker cooler 19. As a result, the amount of dioxins discharged from the cement manufacturing facility 10 and organochlorine compounds such as PCBs can be reduced as compared with the prior art.

  Further, a part of the cement raw material in the storage silo 14 is separated using the raw material sorting pipe 154, and the sorted cement raw material is separated from the lower stage portion of the preheater 16 in the first exhaust gas branch pipe 150. A portion between the connecting portion and the valve 151 may be introduced into the exhaust gas passing through. Thereby, the discharge | release amount of organic chlorine compounds, such as dioxins discharged | emitted from the cement manufacturing equipment 10, and PCB, can further be reduced.

Here, the rate of reduction of organochlorine compounds in the exhaust gas released to the atmosphere (compared to the unit using heating raw material), compared with the one using the cement manufacturing facility 10 of Example 1 and the one using the conventional cement manufacturing facility Report the results of a survey of 50 kg / t.cli).
That is, when the separated exhaust gas was put into the lower stage of the preheater 16, it was possible to remove 60% by weight of PCB from the exhaust gas. These are typical harmful substances that must be removed from the dedusted gas.

  Further, when a part of the cement raw material is separated by the raw material separation pipe 154 and the separated cement raw material is put into the lower stage of the preheater 16 together with the exhaust gas passing through the first exhaust gas branch pipe 150. Was able to remove 60% by weight of PCB from the exhaust gas.

It is a schematic block diagram of the cement baking equipment to which the organic chlorine compound reduction method in the cement manufacturing equipment concerning Example 1 of this invention was applied.

Explanation of symbols

10 Cement production equipment,
16 Preheater (high temperature part),
18 Rotary kiln,
19 Clinker cooler (hot part),
21 exhaust gas duct,
A raw material grinding process section,
F1 fan.

Claims (6)

In a method for reducing organochlorine compounds in a cement production facility, which is obtained by firing cement clinker from cement raw material dried and pulverized in a raw material pulverization process section, and producing cement from the cement clinker.
A heat source supply step of containing an organic chlorine compound and supplying exhaust gas generated during firing of the cement clinker to the raw material grinding step as a heat source for drying the cement raw material;
A portion of the exhaust gas supplied to the raw material pulverization process unit is fractionated and introduced into a high temperature part that is 800 ° C. or higher during normal operation of the cement production facility, and the organic chlorine compound contained in the exhaust gas is pyrolyzed. A method for reducing organochlorine compounds in a cement manufacturing facility, comprising: The exhaust gas is a gas discharged from the upper part of the preheater at the time of firing the cement clinker,
The method for reducing organochlorine compounds in a cement production facility according to claim 1, wherein the high temperature part is a lower part of the preheater. The exhaust gas is a gas discharged from the upper part of the preheater at the time of firing the cement clinker,
2. The method for reducing organochlorine compounds in a cement manufacturing facility according to claim 1, wherein the high temperature portion is in the vicinity of an input portion of a cement clinker discharged from a rotary kiln in the clinker cooler. The upper part of the preheater and the raw material crushing process part are connected by an exhaust gas duct having a fan,
The method for reducing organochlorine compounds in a cement manufacturing facility according to claim 2 or 3, wherein the exhaust gas is fractionated from a portion of the exhaust gas duct downstream from the fan.   A portion of the cement raw material supplied to the upper part of the preheater is fractionated, and the separated cement raw material is charged into the lower stage of the preheater that becomes 800 ° C. or higher during normal operation of the cement production facility, and an organic chlorine compound A method for reducing organochlorine compounds in a cement production facility, comprising a decomposition step of thermally decomposing the material.   6. The cement according to claim 5, wherein the sorted cement raw material is discharged from an upper part of the preheater during firing of the cement clinker and is supplied into an exhaust gas supplied to a lower stage of the preheater. Method for reducing organochlorine compounds in manufacturing facilities.

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