JP6797661B2 - Chlorine bypass dust treatment method and chlorine bypass dust treatment equipment - Google Patents

Description

The present invention relates to a method and a treatment device for chlorine bypass dust contained in combustion gas extracted from a flow path from a kiln tail of a cement kiln to a lowermost cyclone of a preheater.

Conventionally, in the production of cement, chlorine is treated as a repellent component whose processing amount needs to be controlled. This not only causes chlorine to corrode the reinforcing bars in reinforced concrete, which is known as salt damage to concrete, but also induces coating troubles in the kiln or preheater, which is the cement manufacturing facility, and stabilizes the cement kiln. This is because there is a risk of hindering driving. Therefore, conventionally, in cement manufacturing facilities, so-called chlorine bypass equipment is provided to remove chlorine from the inside of the cement kiln.

Chlorine bypass equipment includes an bleeding device that extracts combustion gas as bleed gas from between the kiln end of the cement kiln and the bottom cyclone of the preheater, and cools the bleed gas to condense and solidify the chlorine contained in the bleed gas. The cooling device that is made into particles and the dust in the kiln such as the particles due to the condensation and solidification of chlorine and the raw material powder contained in the extracted gas (hereinafter, these are collectively referred to as "chlorine bypass dust") are referred to as coarse powder. There is known one provided with a classification device for classifying into fine particles and a recovery device for collecting fine particles (see, for example, Patent Document 1).

Here, "chlorine bypass dust" refers to chlorine compounds such as alkali chlorides such as KCl generated in the process of cooling and solidifying the extracted gas, as well as chlorine compounds such as KCl adhering to the surface of dust in the kiln.

The chlorine bypass dust has a higher chlorine content than the coarse powder because the finer the powder, the smaller the proportion of dust in the kiln. Therefore, by recovering the fine powder, chlorine can be efficiently removed from the cement manufacturing process. On the other hand, since the crude powder has a relatively low chlorine content, it can be returned to the cement kiln as a cement raw material.

Japanese Unexamined Patent Publication No. 2000-354838

However, in recent years, the amount of chlorine brought into the cement kiln has increased due to the increase in the amount of waste processed due to the progress of recycling treatment of various wastes in the cement kiln and the change in the type of waste. Therefore, the chlorine content of the coarse powder of the chlorine bypass dust tends to increase, and there is a possibility that returning the coarse powder to the cement kiln as a raw material may cause a problem.

The present invention has been made in view of the above points, and an object of the present invention is to provide a chlorine bypass dust treatment method and a chlorine bypass dust treatment apparatus capable of coping with an increase in the amount of chlorine brought into a cement kiln.

In order to achieve the above object, the chlorine bypass dust treatment method of the present invention comprises an extraction step of extracting combustion gas as an extraction gas from a flow path between the kiln tail of a cement kiln and the lowermost cyclone of a preheater, and the above-mentioned A cooling step of cooling the extracted gas and condensing and solidifying the chlorine contained in the extracted gas to form chlorine bypass dust, and a classification step of classifying the chlorine bypass dust into coarse powder and fine powder based on a predetermined particle size. If, by heating the coarse powder, and a heating step to volatilize the chlorine-containing substance contained in the meal, the heating step is characterized Rukoto conducted under a negative pressure.

As described above, in the chlorine bypass dust treatment method of the present invention, the classified coarse powder is heated to volatilize the chlorine-containing material contained in the coarse powder to remove chlorine. As a result, even if the coarse powder is returned to the cement kiln again, there are no problems in the operation surface of the cement manufacturing facility and the quality of the cement due to the chlorine-containing substances.

Further, in the method for treating chlorine bypass dust of the present invention, it is preferable that the heating temperature of the crude powder is 600 ° C. or higher and 1100 ° C. or lower in the heating step.

PbCl ₂ , which is a major metal chloride in chlorine bypass dust, has a melting point of 501 ° C. and a boiling point of 950 ° C. Therefore, by setting the heating temperature of the crude powder in the heating step to 600 ° C. or higher, the chlorine-containing material can be volatilized from the crude powder. On the contrary, when the heating temperature is less than 600 ° C., the volatilization amount of the chlorine-containing substance becomes insufficient because the effect of heating is low. Therefore, the heating device in the heating step should be at least 600 ° C. or higher.

Further, from the viewpoint of energy efficiency, it is preferable to use waste heat of cement manufacturing equipment such as kiln combustion exhaust gas for heating the coarse powder, but since the combustion gas temperature of the kiln tail of the cement kiln is about 1000 ° C. , It is difficult to secure waste heat that greatly exceeds the temperature. Further, since the combustion gas temperature of the kiln tail of the cement kiln is about 1000 ° C., if it is heated to a temperature exceeding that temperature (specifically, about 1100 ° C.), it will be contained in the combustion gas of the kiln tail of the cement kiln. Most of the chlorine that was used can be volatilized. Therefore, the heating device in the heating step may be capable of heating up to about 1100 ° C.

Further, in the method for treating chlorine bypass dust of the present invention, it is preferable that the heating step is performed under negative pressure.

When the heating step is performed under negative pressure, the chlorine-containing material contained in the coarse powder is likely to volatilize, so that chlorine can be efficiently removed. For example, even KCl having a melting point of 776 ° C. can be volatilized at 600 ° C. in a negative pressure environment.

Further, in the method for treating chlorine bypass dust of the present invention, as a method of performing the heating step with a negative pressure, the air in the heating device for heating the coarse powder in the heating step is 0.016 m / s or more and 0. A method of sucking at a ventilation speed of .048 m / s or less may be used.

As described above, when the air in the heating device is locally exhausted (drafted) by suction, a negative pressure environment can be easily generated.

Here, the degree of negative pressure due to local exhaust is an index of the ventilation speed around the coarse powder to be heated. When the ventilation speed is less than 0.016 m / s, the volatilization amount of the chlorine-containing substance may not be sufficient because the effect of the negative pressure is low. On the other hand, when the ventilation speed exceeds 0.048 m / s, the amount of coarse powder carried by the local exhaust increases, which is not preferable.

Further, the chlorine bypass dust treatment method of the present invention includes a chlorine concentration measuring step for measuring the chlorine concentration of the crude powder conveyed to the heating step, and based on the measurement result in the chlorine concentration measuring step, said It is preferable to control the classification point in the classification process.

The coarse powder classified by a classification device such as a cyclone separator may have a low chlorine content that does not require the removal of chlorine-containing substances in the heating process, and conversely, the chlorine content is sufficiently removed in the heating process. It may contain too much chlorine to the extent that it cannot. Therefore, if the chlorine content of the coarse powder conveyed to the heating device is monitored and the classification point of the classification device is controlled based on the monitoring result, the chlorine content of the coarse powder can be easily processed in the heating step. It can be adjusted to an amount suitable for.

Further, in the method for treating chlorine bypass dust of the present invention, it is preferable that the chlorine concentration of the crude powder conveyed to the heating device is in the range of 1.5% by mass or more and 8.0% by mass or less.

When the chlorine concentration of the crude powder is less than 1.5% by mass, it is less necessary to remove chlorine, and it may not be possible to reduce the chlorine concentration so much even by heat treatment. On the other hand, when the chlorine concentration of the crude powder exceeds 8.0% by mass, the chlorine may not be sufficiently removed by the heat treatment.

Further, in order to achieve the above object, the chlorine bypass dust treatment device of the present invention includes an bleeding device that bleeds combustion gas as bleed gas from between the kiln tail of the cement kiln and the lowermost cyclone of the preheater, and the bleeding device. A cooling device that cools the gas and condenses and solidifies chlorine contained in the extracted gas to form chlorine bypass dust, and a classification device that classifies the chlorine bypass dust into coarse powder and fine powder based on a predetermined particle size. A heating device that heats the coarse powder under negative pressure to volatilize chlorine-containing substances contained in the coarse powder, and a heating device arranged on the downstream side of the heating device to reduce the ventilation speed of air inside the heating device. It is characterized by including a fan that controls the inside of the heating device to make a negative pressure .

As described above, in the chlorine bypass dust treatment apparatus of the present invention, the classified coarse powder is heated to volatilize the chlorine-containing material contained in the coarse powder to remove chlorine. As a result, even if the coarse powder is returned to the cement kiln again, there is no problem in the operation surface of the cement manufacturing facility and the quality of the cement due to chlorine.

Explanatory drawing which shows the schematic structure of the chlorine bypass facility which concerns on embodiment. Explanatory drawing which shows the structure of the heating device of the chlorine bypass facility of FIG. The flowchart of the process until the fine powder and the coarse powder are classified by the chlorine bypass equipment of FIG. The flowchart of the process performed on the coarse powder classified by the chlorine bypass facility of FIG. The graph which shows the relationship between the heating temperature and ventilation speed of the heating apparatus of the chlorine bypass facility of FIG. 1 and the chlorine removal rate of coarse powder.

Hereinafter, the chlorine bypass facility C (chlorine bypass dust treatment device) according to the embodiment of the present invention will be described with reference to the drawings. In each drawing, the solid line arrow indicates the flow of gas or dust, and the broken line arrow indicates the flow of the control signal.

First, the schematic configuration of the chlorine bypass facility C will be described with reference to FIG.

As shown in FIG. 1, the chlorine bypass facility C is an extracted gas which is a combustion gas extracted from between the kiln end of the cement kiln K and the lowermost cyclone of the preheater P for preheating the cement raw material sent to the cement kiln K. This is a facility for removing chlorine from G.

The chlorine bypass facility C supplies cold air to the inside of the probe 1 (flow path, bleeding device) provided between the kiln end of the cement kiln K and the lowermost cyclone of the preheater P, and the bleeding gas G. The first cooling fan 2 (cooling device) that condenses and solidifies chlorine contained in chlorine to form chlorine bypass dust, the cyclone separator 3 (classification device) that classifies chlorine bypass dust, and the chlorine bypass dust classified by the cyclone separator 3. It is provided with a fine powder processing unit 10 for treating the dust D1 which is the fine powder of the above, and a coarse powder processing unit 20 for treating the dust D2 which is a coarse powder of chlorine bypass dust classified by the cyclone separator 3.

Inside the probe 1, the bleed gas G is cooled by the cold air supplied by the first cooling fan 2, and the chlorine contained in the bleed gas G becomes the first gas G1 containing chlorine bypass dust condensed and solidified.

The first gas G1 is sent to the cyclone separator 3 provided in the chlorine bypass facility C, and is a mixture of the first dust D1 which is a fine powder of the chlorine bypass dust and the second gas G2 which is a gas component of the first gas G1 and chlorine. It is separated from the second dust D2, which is a coarse powder of bypass dust. The classification point of the cyclone separator 3 can be controlled by changing the rotation speed of the rotor or the like, and is controlled based on a signal from the control unit 27 of the coarse powder processing unit 20 described later. As an example of the reference classification point, it is 12 μm.

The mixture of the first dust D1 and the second gas G2, which are fine powders classified by the cyclone separator 3, is sent to the fine powder processing unit 10. On the other hand, the second dust D2, which is a coarse powder, is sent to the coarse powder processing unit 20.

The fine powder processing unit 10 is connected to a cooler 11 to which a mixture of the first dust D1 and the second gas G2, which are fine powder, is sent, a second cooling fan 12 to supply cold air to the cooler 11, and the cooler 11. The first bug filter 13 is provided, the first dust tank 14 connected to the cooler 11 and the first bug filter 13, and the first fan 15 connected to the first bug filter 13 are provided.

Inside, the cooler 11 cools a mixture of the first dust D1 and the second gas G2, which are fine powders of chlorine bypass dust, by the cold air supplied by the second cooling fan 12.

The first bug filter 13 collects the fourth dust D4, which is a fine powder of chlorine bypass dust, from the third gas G3 extracted from the cooler 11. The fourth dust D4 is sent to the first dust tank 14 together with the fine powder D3 of the chlorine bypass dust recovered by the cooler 11. Further, the fourth gas G4 separated by the first bug filter 13 is returned to the gas flow path in the cement manufacturing facility such as a cement kiln.

The first dust tank 14 stores the fine powder of the recovered chlorine bypass dust.

The coarse powder processing unit 20 is attached to a chlorine measuring device 21 for measuring the chlorine concentration of the second dust D2, which is a coarse powder of chlorine bypass dust, a distribution device 22 for selectively transporting the second dust D2, and a distribution device 22. The second dust tank 23 connected, the heating device 24 connected to the distribution device 22 and the second dust tank 23, the second bug filter 25 connected to the heating device 24, and the heating device 24 and subsequent devices are connected. A second fan 26 for local exhaust and a control unit 27 are provided.

The chlorine measuring device 21 may be any device capable of measuring the amount of chlorine in the second dust D2, which is a coarse powder of the chlorine bypass dust discharged from the cyclone separator 3. For example, it may be configured using a fluorescent X-ray analyzer (XRF). The measurement result of the chlorine concentration measured by the chlorine measuring device 21 is transmitted to the control unit 27 at any time.

The distribution device 22 uses a signal from the control unit 27 to send the second dust D2, which is a coarse powder of the chlorine bypass dust, to the cement kiln system side, the second dust tank 23, the heating device 24 side, and the system. Select the destination from the outside.

Specifically, when the chlorine concentration of the second dust D2, which is the coarse powder of the chlorine bypass dust measured by the chlorine measuring device 21, is sufficiently low and it is not necessary to remove the chlorine, it is heated as the sixth dust D6. Transport to cement kiln system without treatment. When the chlorine concentration is high enough to require removal of chlorine and is lower than a predetermined value, it is transported to the second dust tank 23 and the heating device 24 side as the seventh dust D7. When the chlorine concentration exceeds a predetermined value, it is discharged to the outside of the system as the eighth dust D8 so as not to be sent to the heating device 24.

Specifically, in the chlorine bypass device C, when the chlorine concentration of the second dust D2, which is a coarse powder of the chlorine bypass dust, is less than 1.5% by mass, the chlorine bypass device C is transported to a cement kiln system and 1.5% by mass. When it is% or more and 8.0% by mass or less, it is conveyed to the second dust tank 23 and the heating device 24 side. If it exceeds 8.0% by mass, it is discharged to the outside of the system so as not to be sent to the heating device 24.

This is because when the chlorine concentration of the second dust D2, which is a coarse powder of chlorine bypass dust, is less than 1.5% by mass, it is less necessary to remove chlorine, and even if heat treatment is performed, chlorine is not so much. This is because the concentration may not be reduced, and if it exceeds 8.0% by mass, chlorine may not be sufficiently removed by the heat treatment.

In the second dust tank 23, the seventh dust D7, which is a coarse powder of chlorine bypass dust to be heated, is stored. By using the second dust tank 23, the seventh dust D7 can be sent to the heating device 24 at an arbitrary timing.

That is, in the chlorine bypass facility C, the operating time of the heating device 24 can be arbitrarily set by the second dust tank 23. The second dust tank 23 may be omitted when the processing capacity of the heating device 24 is sufficiently high.

The chlorine bypass facility C is provided with a bypass route for sending the seventh dust D7, which is a coarse powder of chlorine bypass dust, to the heating device 24 without passing through the second dust tank 23.

The heating device 24 heats the seventh dust D7, which is a coarse powder of chlorine bypass dust sent from the distribution device 22 or the second dust tank 23, together with air to volatilize the chlorine-containing material contained in the seventh dust D7. .. As a result, the seventh dust D7 becomes the ninth dust D9, which is a coarse powder having a low chlorine content. The ninth dust D9 is transported to a cement kiln system and becomes a cement raw material.

The fifth gas G5, which is the extracted gas from the heating device 24, is sent to the second bug filter 25, and the chlorine-containing substance contained in the fifth gas G5 is condensed and solidified to form the tenth dust D10. It is separated from the sixth gas G6, which is a gas component of the fifth gas G5.

The sixth gas G6 sucked by the second fan 26 and separated by the second bag filter 25 may be released to the atmosphere or may be sent to a gas flow path in a cement manufacturing facility such as a cement kiln.

Further, the second fan 26 controls the ventilation speed inside by extracting air from the inside of the heating device 24 through the second bug filter 25, and creates a negative pressure environment inside the heating device 24.

The control unit 27 controls the classification point of the cyclone separator 3 and the operation of the distribution device 22 based on the measurement result of the chlorine measuring device 21. Further, the control unit 27 controls the temperature and ventilation speed of the heating device 24 (that is, driving the second fan 26) based on the signal from the heating device 24.

Next, the configuration of the heating device 24 will be described with reference to FIG.

As shown in FIG. 2, the heating device 24 includes a kiln 24a, which is an externally heated rotary kiln, a seventh dust D7, which is a coarse powder of chlorine bypass dust, and a supply unit 24b, which supplies air to the kiln 24a, and a chlorine content. A discharge section 24c for discharging the ninth dust D9, which is a low coarse powder, into the cement kiln system, a suction probe 24d provided in the discharge section 24c, a suction fan 24e connected to the suction probe 24d, and a kiln inner cylinder portion. It is provided with a wind speed sensor 24f for measuring the wind speed of the gas in 24a1. The fifth gas G5, which is the extracted gas from the kiln 24a, is attracted from the discharge unit 24c to the second bug filter 25 by the suction fan 26.

The kiln 24a has a rotatable cylindrical inner cylinder portion 24a1, a tubular heating portion 24a2 through which the inner cylinder portion 24a1 is inserted, and a plurality of thermometers 24a3 installed in the heating portion 24a2. .. The thermometer 24a3 transmits a measurement result to the control unit 27 at any time, and the control unit 27 controls the operation of the heating unit 24a2 based on the measurement result.

The heating portion 24a2 makes it possible to heat the internal space of the inner cylinder portion 24a1 to a temperature of 600 ° C. to 1100 ° C.

The reason why the heating performance of the heating device 24 has such a value is as follows.

That is, PbCl ₂ , which is a major metal chloride in chlorine bypass dust, has a melting point of 501 ° C. and a boiling point of 950 ° C. Therefore, by setting the heatable temperature of the heating device 24 to 600 ° C. or higher, the chlorine-containing material can be volatilized from the seventh dust D7. On the contrary, when the heatable temperature is less than 600 ° C., the volatilization amount of the chlorine-containing substance becomes insufficient because the heating effect is low.

Further, from the viewpoint of energy efficiency, it is preferable to use waste heat of cement manufacturing equipment such as kiln combustion exhaust gas for heating the seventh dust D7. However, since the combustion gas temperature of the kiln tail of cement kiln K is about 1000 ° C., it is difficult to secure waste heat that greatly exceeds that temperature.

Further, since the combustion gas temperature of the kiln tail of cement kiln K is about 1000 ° C., if it is heated to a temperature exceeding that temperature (specifically, about 1100 ° C.), it will be contained in the combustion gas of the kiln tail of cement kiln K. Most of the chlorine contained in the kiln can be volatilized. Therefore, the heating device 24 is configured to be able to heat up to about 1100 ° C.

However, the heating performance of the heating device 24 may be appropriately changed depending on the heating performance of the cement kiln K and the preheater P, the type of dust to be treated, and the like.

The suction probe 24d extends to the inside of the inner cylinder portion 24a1 of the kiln 24a, and draws air from the inside of the inner cylinder portion 24a1 in response to the drive of the suction fan 24e and the second fan 26. The suction fan 24e is driven in response to a signal transmitted from the control unit 27 based on the measurement result of the wind speed sensor 24f, and is used to assist the driving of the second fan 26.

That is, in the chlorine bypass facility C, the adjustment of the wind speed inside the inner cylinder portion 24a1 of the kiln 24a is performed by the control unit 27 via the second fan 26 and the suction fan 24e. If the driving force of the second fan 26 is sufficiently high, the suction fan 24e may be omitted.

In this heating device 24, the transport direction of the seventh dust D7, which is a coarse powder of the chlorine bypass dust to be introduced, and the ventilation direction by the second fan 26 are parallel. As a result, the chlorine-containing material volatilized in the heated portion of the inner cylinder portion 24a1 is not condensed and solidified on the ninth dust D9, which is a coarse powder having a low chlorine content, and is discharged as the fifth gas G5.

Next, the treatment performed in the chlorine bypass facility C will be described with reference to FIGS. 1, 3 and 4.

First, with reference to FIGS. 1 and 3, a process up to classifying the first dust D1 which is a fine powder and the second dust D2 which is a coarse powder will be described.

First, the probe 1 extracts the extracted gas G, which is a combustion gas, from between the kiln tail of the cement kiln K, which is a rotary kiln for firing the cement raw material, and the preheater P, which preheats the cement raw material sent to the cement kiln K. (Fig. 3 / STEP100).

This step is the bleeding step in the present invention. At this time, the temperature of the extracted gas G is about 1000 ° C.

Next, the first cooling fan 2 supplies cold air into the probe 1 to cool the extracted gas G, and condenses and solidifies the chlorine contained in the extracted gas G to form chlorine bypass dust (FIG. 3 / STEP101). ..

This step is the cooling step in the present invention. By this treatment, the extracted gas G becomes the first gas G1 containing chlorine bypass dust. At this time, the extracted gas G is cooled to 600 ° C. to 700 ° C.

Next, the cyclone separator 3 classifies chlorine bypass dust at a reference classification point (for example, 12 μm) (FIG. 3 / STEP102).

This step is the classification step in the present invention. By this treatment, the first gas G1 is a mixture of the first dust D1 which is a fine powder of chlorine bypass dust and the second gas G2 which is a gas component of the first gas G1 and the second coarse powder of chlorine bypass dust. Separated from dust D2. The classification point of the cyclone separator 3 may be appropriately changed based on the performance of the heating device 24 and the like.

The above treatments of STEP100 to STEP102 are the treatments until the first dust D1 which is a fine powder and the second dust D2 which is a coarse powder are classified.

The first dust D1, which is a fine powder of chlorine bypass dust classified by the above step, is treated by a known method performed in a conventional chlorine bypass facility. On the other hand, the second dust D2, which is a coarse powder of chlorine bypass dust, is treated by the following method.

Hereinafter, the processing performed by the coarse powder processing unit 20 will be described with reference to FIGS. 1 and 4.

First, the chlorine measuring device 21 measures the amount of chlorine contained in the second dust D2, which is the coarse powder discharged from the cyclone separator 3 (FIG. 4 / STEP200).

This treatment is the chlorine concentration measuring step in the present invention. The measurement result of the chlorine concentration measured by the chlorine measuring device 21 is transmitted to the control unit 27 at any time. After that, the control unit 27 controls the classification point of the cyclone separator 3 and the operation of the distribution device 22 based on the measurement result of the chlorine measuring device 21.

Specifically, first, the control unit 27 determines whether or not the chlorine concentration of the second dust D2 is less than 1.5% by mass (FIG. 4 / STEP201).

When the chlorine concentration of the second dust D2 is less than 1.5% by mass (YES in STEP201), the chlorine concentration of the second dust D2 is sufficiently low and the chlorine does not need to be removed. , The second dust D2 is transported to the cement kiln system as the sixth dust D6 (FIG. 4 / STEP202).

In this case, since a large amount of chlorine bypass dust that can be removed from chlorine and returned to the raw material is contained on the first dust D1 side, the chlorine concentration of the second dust D2 to be transported in the next and subsequent treatments The control unit 27 changes the classification point of the cyclone separator 3 to the finer grain side (fine powder side), and ends the current process (FIG. 4 / STEP203).

On the other hand, when the chlorine concentration of the second dust D2 is 1.5% by mass or more (NO in STEP201), the control unit 27 has the chlorine concentration of the second dust D2 exceeding 8.0% by mass. It is determined whether or not it is (Fig. 4 / STEP204).

When the chlorine concentration of the second dust D2 exceeds 8.0% by mass (YES in STEP 204), the distribution device 22 discharges the second dust D2 as the eighth dust D8 to the outside of the system (when it is YES in STEP 204). FIG. 4 / STEP205).

In this case, since chlorine bypass dust that can be removed from chlorine and returned to the raw material cannot be detected, the control unit 27 sets the chlorine concentration of the second dust D2 to be transported in the next and subsequent treatments. , The classification point of the cyclone separator 3 is changed to the coarser grain side (coarse powder side), and the present processing is completed (FIG. 4 / STEP206).

On the other hand, when the chlorine concentration of the second dust D2 is 8.0% by mass or less (NO in STEP204), the distribution device 22 sets the second dust D2 as the seventh dust D7 and sets the second dust D7 as the second dust. Distribute to the tank 23 and the heating device 24 side (FIG. 4 / STEP207).

As described above, in the chlorine bypass facility C, 1.5% by mass or more and 8.0% by mass or less is adopted as the chlorine concentration as a reference for the operation of the distribution device 22.

This is because when the chlorine concentration of the second dust D2, which is a coarse powder of chlorine bypass dust, is less than 1.5% by mass, it is less necessary to remove chlorine, and even if a heating step is performed, the chlorine concentration is not so high. This is because if the chlorine concentration exceeds 8.0% by mass, it may not be possible to sufficiently remove chlorine only by performing the heating step.

However, since this numerical value is a numerical value in consideration of the general properties of chlorine bypass dust, it is not always necessary to use this numerical value as a reference for the operation of the distributor 22, and it may be set as appropriate.

Next, the heating device 24 heats the 7th dust D7 together with air to 600 ° C. to 1100 ° C. to volatilize the chlorine-containing material contained in the 7th dust D7 (FIG. 4 / STEP208).

This step is the heating step in the present invention. The heating temperature and the ventilation speed in the heating device 24 (that is, the air pressure in the heating device 24) in this heating step are adjusted by the control unit 27 according to the residence time in the heating device 24 of the seventh dust D7.

Next, the heating device 24 conveys the heated seventh dust D7 as the ninth dust D9 to the cement kiln system, and also transfers the fifth gas G5, which is a gas component generated during heating, to the second bug filter 25. (Fig. 4 / STEP209).

Next, the second bug filter 25 collects the tenth dust D10 from the fifth gas G5, which is an exhaust gas, and separates the tenth dust D10 into the sixth gas G6, which is a gas component of the fifth gas G5 (FIG. 4 / STEP210).

Like the fifth dust D5, the tenth dust D10 is properly treated in the cement finishing step.

Finally, the second fan 26 transports the sixth gas G6 discharged from the second bug filter 25 to a cement kiln system or the like, or releases it to the atmosphere, and ends the treatment (FIG. 4 / STE211).

The above steps of STEP200 to STEP211 are the processes performed by the coarse powder processing unit 20.

As described above, in the chlorine recovery method carried out in the chlorine bypass facility C, the classified coarse powder (second dust D2 (more specifically, the seventh dust D7 distributed from the second dust D2)) is heated. Then, the chlorine-containing substances contained in the crude powder are volatilized and removed.

Therefore, even if the coarse powder is returned to the cement kiln K again, there is no problem in the operation surface of the cement manufacturing facility and the quality of the cement due to the chlorine content.

Next, with reference to FIG. 5, the relationship between the heating temperature (indicated value of the thermometer 24a3) and the ventilation rate and the chlorine removal rate in the heating device 24 of the chlorine bypass facility C will be described.

As the test conditions for creating the graph of FIG. 5, in all measurements, coarse powder (7th dust D7) having a chlorine content of 3.0% by mass before heating was used, and the amount of heat treatment of the coarse powder was used. The amount of coarse powder fed and the rotation speed of the inner cylinder portion 24a1 were adjusted so that the value was 100 kg / hour.

As is clear from this graph, the higher the ventilation speed of the inner cylinder portion 24a1, the higher the chlorine removal rate at the same heating temperature.

For example, when the target chlorine concentration of the crude powder is set to 1.5% by mass, the target value of the chlorine removal rate is 50% because the chlorine content before heating is 3.0% by mass, but the inner cylinder. When the ventilation speed of the part 24a1 is 0.032 m / s, the target value is achieved at 900 ° C., and when the ventilation speed is 0.048 m / s, the target value is achieved at 700 ° C.

That is, it was found that when the ventilation speed (that is, the degree of negative pressure) is sufficient, the chlorine-containing substance can be sufficiently volatilized even when the heating temperature is around 600 ° C.

However, when a negative pressure environment is created by locally exhausting (drafting) the air in the heating device 24 as in this test, if the ventilation speed is less than 0.016 m / s, the negative pressure The volatilization amount of the chlorine-containing material was not sufficient due to the low effect of. On the other hand, when the ventilation speed exceeds 0.048 m / s, the amount of coarse powder carried by the local exhaust increases, and the amount of coarse powder discharged before sufficient heat treatment is performed increases. ..

The ventilation speed may be appropriately changed depending on the performance of the heating device 24 and the like. Further, when the heatable temperature of the heating device 24 is sufficiently high, it is not necessary to set the negative pressure.

Although the illustrated embodiment has been described above, the present invention is not limited to such an embodiment.

For example, in the above embodiment, an externally heated rotary kiln is used as the heating device 24, but the heating device of the present invention may be any as long as it can volatilize the chlorine-containing material contained in the coarse powder to be treated. You may use the heating device of. For example, a U-turn kiln or the like may be used.

1 ... probe (flow path, bleeding device), 2 ... first cooling fan (cooling device), 3 ... cyclone separator (classifying device), 10 ... fine powder processing unit, 11 ... cooler, 12 ... second cooling fan, 13 ... 1st bug filter, 14 ... 1st dust tank, 15 ... 1st fan, 20 ... coarse powder processing unit, 21 ... chlorine measuring device, 22 ... distributor, 23 ... 2nd dust tank, 24 ... heating device, 24a ... Kiln, 24a1 ... Inner cylinder, 24a2 ... Heating, 24a3 ... Thermometer, 24b ... Supply, 24c ... Discharge, 24d ... Suction probe, 24e ... Suction fan, 24f ... Wind speed sensor, 25 ... Second bug filter , 26 ... 2nd fan, 27 ... Control unit, C ... Chlorine bypass equipment (chlorine bypass dust processing device), D1 ... 1st dust (fine powder), D2 ... 2nd dust (coarse powder), D3 ... 3rd dust , D4 ... 4th dust, D5 ... 5th dust, D6 ... 6th dust, D7 ... 7th dust, D8 ... 8th dust, D9 ... 9th dust, D10 ... 10th dust, G ... Extraction gas, G1 ... 1st gas, G2 ... 2nd gas, G3 ... 3rd gas, G4 ... 4th gas, G5 ... 5th gas, G6 ... 6th gas, K ... cement kiln, P ... preheater.

Claims (6)

An air extraction process in which combustion gas is extracted as extraction gas from the flow path between the kiln butt of the cement kiln and the bottom cyclone of the preheater, and
A cooling step of cooling the extracted gas and condensing and solidifying chlorine contained in the extracted gas to form chlorine bypass dust.
A classification step of classifying the chlorine bypass dust into coarse powder and fine powder based on a predetermined particle size, and
It is provided with a heating step of heating the coarse powder to volatilize the chlorine-containing material contained in the coarse powder.
The method for treating chlorine bypass dust, wherein the heating step is performed under negative pressure. In the method for treating chlorine bypass dust according to claim 1,
A method for treating chlorine bypass dust, which comprises setting the heating temperature of the crude powder to 600 ° C. or higher and 1100 ° C. or lower in the heating step. In the method for treating chlorine bypass dust according to claim 1 or 2.
A method for treating chlorine bypass dust, which comprises sucking air in a heating device for heating the coarse powder at a ventilation rate of 0.016 m / s or more and 0.048 m / s or less in the heating step. The method for treating chlorine bypass dust according to any one of claims 1 to 3.
It is equipped with a chlorine concentration measuring process that measures the chlorine concentration of the coarse powder transported to the heating device.
A method for treating chlorine bypass dust, which comprises controlling a classification point in the classification step based on a measurement result in the chlorine concentration measuring step. The method for treating chlorine bypass dust according to any one of claims 1 to 4.
A method for treating bypass dust, which comprises setting the chlorine concentration of the crude powder conveyed to the heating device in the range of 1.5% by mass or more and 8.0% by mass or less. An bleeding device that bleeds combustion gas as bleed gas from between the kiln butt of the cement kiln and the bottom cyclone of the preheater,
A cooling device that cools the extracted gas and condenses and solidifies chlorine contained in the extracted gas to form chlorine bypass dust.
A classification device that classifies the chlorine bypass dust into coarse powder and fine powder based on a predetermined particle size.
A heating device that heats the coarse powder under negative pressure to volatilize the chlorine-containing material contained in the coarse powder .
Treatment of bypass dust, which is arranged on the downstream side of the heating device and includes a fan that controls the ventilation speed of air inside the heating device to create a negative pressure inside the heating device. apparatus.