JP6919364B2 - Kiln gas bleeding device and bleeding method - Google Patents

Description

The present disclosure relates to a kiln gas bleeding device and a bleeding method.

A technique for removing chlorine from the cement manufacturing process by extracting kiln gas having a temperature of about 900 to 1300 ° C. from the kiln is known. Such kiln gas is cooled by mixing the cooling gas. Patent Document 1 proposes a technique for forming a swirling flow by introducing a cooling gas along the inner wall surface of a separate cooling flow path for kiln gas. By using such a technique, it is possible to prevent the volatile matter precipitated by cooling the kiln gas from adhering to the inner wall surface, and to preferably separate the volatile matter and the dust.

JP-A-2007-44577

The amount of kiln gas flowing through the kiln butt and the concentration of dust contained in the kiln gas vary depending on the operating conditions of the cement kiln. Therefore, the amount of kiln gas and the amount of dust extracted by the bleeding device fluctuate. When the concentration of dust contained in the kiln gas introduced into the separation cooling pipe becomes high due to such fluctuations, the efficiency of chlorine extraction decreases. As a countermeasure for this problem, a method of increasing the flow rate of the cooling gas introduced into the separation cooling pipe and increasing the separation efficiency by a swirling flow can be considered. However, if the flow rate of the cooling gas is simply increased, a part of the cooling gas may flow toward the kiln butt. In this case, the kiln gas flowing through the kiln tail is cooled, and the thermal efficiency of the cement firing apparatus is lowered. In order to avoid such a phenomenon, it is necessary to take measures such as reducing the flow rate of the cooling gas introduced into the separation cooling pipe.

However, if the flow rate of the cooling gas introduced into the separation cooling pipe is reduced, the speed of the swirling flow in the separation cooling pipe is reduced. As a result, the dust flowing around the outer peripheral portion of the separation cooling pipe is likely to be deposited on the bottom of the separation cooling pipe due to the swirling flow. Due to such accumulation of dust, the swirling flow in the separation cooling pipe is disturbed, and the accuracy of separating dust and volatile matter is lowered. As a result, there is a concern that the amount of dust mixed in the volatile matter may increase and the chlorine extraction efficiency may decrease.

Therefore, an object of the present invention is to provide a kiln gas bleeding device capable of stably continuing operation while maintaining a high chlorine bleeding efficiency in one aspect. Another object of the present invention is to provide a method for extracting chlorine gas, which can continue stable operation while maintaining high chlorine extraction efficiency.

In one aspect, the present invention cools the kiln gas by mixing the kiln gas extracted from the kiln and the cooling gas, and separates at least a part of the dust from the mixed gas containing the kiln gas and the cooling gas to separate the separated gas. Separate cooling on the introduction path where the cooling gas is introduced into the separation cooling pipe and on the downstream side of the introduction path so that the separation cooling pipe to be obtained and the swirling flow of the mixed gas having the substantially central axis of the separation cooling pipe as the swirl axis are generated. A recovery unit that is connected to the pipe and collects at least a part of the dust that is centrifuged by the swirling flow, and a volatile matter that is connected to the separation cooling pipe on the downstream side of the introduction path and precipitates in the separation cooling pipe from the separation gas. The volatile matter removing part to be removed, the first suction device provided on the downstream side of the volatile matter removing part and sucking the separated gas of the separation cooling pipe through the volatile matter removing part, and the downstream side or the collecting part of the collecting part. Provided is a kiln gas bleeding device including a second suction device for sucking the mixed gas of the separation cooling pipe.

The bleeding device includes a collecting unit that centrifuges and collects at least a part of dust by a swirling flow of a mixed gas. Then, a second suction device that sucks the mixed gas of the separation cooling pipe through this recovery unit is provided. Therefore, the accumulation of dust in the separation cooling pipe can be reduced, and the swirling flow can be suppressed from being disturbed by the accumulation of dust. Therefore, the bleeding device can continue to operate stably while maintaining a high chlorine bleeding efficiency.

The recovery unit has a flow path extending in the tangential direction of the separation cooling pipe along the swirling direction of the swirling flow when viewed from the downstream side to the upstream side of the separation cooling pipe, and the second suction device has a flow path. It is preferable that it is connected to the downstream side of the. As a result, the dust contained in the mixed gas is more smoothly recovered in the recovery section. Therefore, the operation can be continued more stably.

The bleeding device adjusts at least one of the flow rate of the cooling gas, the suction gas amount of the first suction device, and the suction gas amount of the second suction device according to the amount of dust contained in the kiln gas extracted into the separation cooling pipe. It is preferably configured to adjust. Even if the amount of dust contained in the kiln gas fluctuates, stable operation can be performed by adjusting at least one of the flow rate of the cooling gas, the amount of suction gas of the first suction device, and the amount of suction gas of the second suction device. You can continue.

The second suction device provided in the recovery unit may be an ejector. The ejector can suck the mixed gas and collect the dust in parallel. Therefore, the device configuration becomes compact, and restrictions on the installation location of the bleed air device can be reduced.

In another aspect, the present invention rotates the substantially central axis of the separation cooling pipe by extracting air from the kiln into the separation cooling pipe and introducing the cooling gas into the separation cooling pipe to join the kiln gas. The dust contained in the mixed gas is centrifuged and recovered in the recovery unit by the introduction step of generating a swirling flow of the mixed gas containing the kiln gas and the cooling gas, and the swirling flow. The removal step includes a recovery step of obtaining a separated gas with reduced dust, and a removing step of introducing the separated gas into the volatile matter removing section and removing the volatile matter precipitated in the separation cooling pipe from the separated gas. Provided is a kiln gas extraction method in which the separated gas of the separation cooling pipe is sucked by the first suction device through the volatile component removing unit, and the mixed gas of the separation cooling pipe is sucked by the second suction device in the recovery step.

In the above bleeding method, in the recovery step of centrifuging at least a part of the dust by the swirling flow of the mixed gas and collecting it in the recovery section, the mixed gas of the separation cooling pipe is sucked by the second suction device through the recovery section. Therefore, the accumulation of dust on the separation cooling pipe is reduced, and it is possible to prevent the swirling flow from being disturbed by the accumulation of dust. Therefore, the above-mentioned bleeding method can continue stable operation while maintaining high chlorine bleeding efficiency.

When looking from the downstream side to the upstream side of the separation cooling pipe, in the recovery process, the mixed gas is derived from the separation cooling pipe by a flow path extending in the tangential direction of the separation cooling pipe along the swirling direction of the swirling flow. Is preferable. As a result, the dust contained in the mixed gas is more smoothly recovered in the recovery section. Therefore, the operation can be continued more stably.

An adjustment step of adjusting at least one of the flow rate of the cooling gas, the amount of the suction gas of the first suction device, and the amount of the suction gas of the second suction device according to the amount of dust contained in the kiln gas extracted in the above-mentioned extraction step is performed. It is preferable to have. Even if the amount of dust contained in the kiln gas fluctuates, stable operation can be performed by adjusting at least one of the flow rate of the cooling gas, the amount of suction gas of the first suction device, and the amount of suction gas of the second suction device. You can continue.

The second suction device that sucks the mixed gas in the recovery step may be an ejector. The ejector can suck the mixed gas and collect the dust in parallel. Therefore, the device configuration becomes compact, and the versatility of the kiln gas bleeding method can be improved.

In one aspect, the present invention can provide a kiln gas bleeding device capable of stably continuing operation while maintaining a high chlorine bleeding efficiency. Further, in another aspect, the present invention can provide a kiln gas bleeding method capable of stably continuing operation while maintaining a high chlorine bleeding efficiency.

FIG. 1 is a diagram showing an outline of a kiln gas bleeding device. FIG. 2 is an enlarged view showing a part of the kiln gas bleeding device of FIG. FIG. 3 is a view when the separation cooling pipe side is viewed from the cross section taken along line III-III of FIG. FIG. 4 is a block diagram showing an example of a control system in the bleed air device. FIG. 5 is a diagram showing a modified example of the kiln gas bleeding device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings in some cases. However, the following embodiments are examples for explaining the present invention, and the present invention is not intended to be limited to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and duplicate description may be omitted in some cases. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratio of each element is not limited to the ratio shown in the figure.

FIG. 1 is a diagram showing an outline of a kiln gas bleeding device 100 according to the present embodiment. The air extraction device 100 is provided in the cement firing device, and extracts the kiln gas containing volatile components such as chlorine generated by the production of the cement clinker to reduce the volatile components such as chlorine in the cement firing device. The bleeding device 100 cools the kiln gas and separates the dust contained in the kiln gas to obtain the separated gas, the separation cooling pipe 12, the introduction path 13 connected to the separation cooling pipe 12, and the downstream side of the introduction path 13. A recovery unit 30 connected to the separation cooling pipe 12 to collect dust, a volatile matter removing unit 20 connected to the separation cooling pipe 12 on the downstream side of the introduction path 13, and a volatile matter removing unit 20 provided on the downstream side of the volatile matter removing unit 20. , The first suction device 40 that sucks the separated gas obtained in the separation cooling pipe 12 via the volatile matter removing unit 20 and the separation cooling pipe 12 provided on the downstream side of the recovery unit 30 and through the collection unit 30 are mixed. A second suction device 42 for sucking gas is provided.

One end of the separation cooling pipe 12 is connected to the kiln tail 52 of the kiln 50, and the other end of the separation cooling pipe 12 is connected to the volatile matter removing portion 20. That is, with reference to the flow direction of the kiln gas 60, the kiln tail 52, the introduction path 13, the recovery unit 30, and the volatile matter removing unit 20 are connected to the separation cooling pipe 12 in this order from the upstream side. The introduction path 13 and the recovery unit 30 are connected to the side portion of the separation cooling pipe 12, and the volatile matter removing unit 20 is connected to the end portion of the separation cooling pipe 12. A part of the kiln gas generated in the kiln 50 is drawn by the suction of the first suction device 40 and the second suction device 42 in the separation cooling pipe 12. The rest of the kiln gas rises up the flue 54 and is introduced into, for example, a suspension preheater.

The separation cooling pipe 12 is composed of, for example, a cylindrical pipe, and has an expansion portion 12A on the other end side having an inner diameter larger than that on the one end side. That is, the inner diameter of the expansion portion 12A is larger than the inner diameter on the upstream side of the expansion portion 12A. As described above, the separation cooling pipe 12 has an expansion portion 12A having an inner diameter larger than that on the upstream side on the downstream side, so that dust can be smoothly centrifuged.

The introduction path 13 is a flow path for cooling gas composed of, for example, a cylindrical pipe, and is connected to the vicinity of the kiln gas inlet of the separation cooling pipe 12. An introduction fan 14 is provided on the upstream side of the introduction path 13. The introduction fan 14 allows the cooling gas (for example, the atmosphere) to flow through the introduction path 13 and be introduced into the separation cooling pipe 12. Examples of the introduction fan 14 include ordinary blowers such as a sirocco fan and a turbo fan.

FIG. 2 is an enlarged view showing the separation cooling pipe 12 of the kiln gas bleeding device 100 and its vicinity. In the separation cooling pipe 12, the kiln gas 60 is introduced from one end side (upstream side), and the separation gas 66 after the separation cooling treatment is discharged from the other end side (downstream side). The kiln gas 60 contains dust as a solid content together with a gaseous volatile content at the inlet of the separation cooling pipe 12. The separated gas 66 obtained by separating at least a part of the dust contained in the kiln gas 60 has a lower dust concentration than the kiln gas 60.

The introduction path 13 is connected to the separation cooling pipe 12 so as to extend in the tangential direction of the outer circumference of the separation cooling pipe 12. The cooling gas 62 introduced from the introduction path 13 moves along the inner wall surface of the separation cooling pipe 12 to form a curtain of the cooling gas 62. This protects the inner wall surface of the separation cooling pipe 12 from the high temperature kiln gas 60.

The introduction path 13 has a portion 13a whose inner diameter gradually increases as it approaches the separation cooling pipe 12. As a result, the inner diameter of the portion of the introduction path 13 on the side of the separation cooling pipe 12 is larger than the inner diameter of the portion on the upstream side of the portion. As a result, when adjusting the introduction amount of the cooling gas, the rate of change of the introduction amount is reduced, and the turbulence of the swirling flow 64 can be suppressed.

The cooling gas 62 introduced from the introduction path 13 along the inner wall surface of the separation cooling pipe 12 and the kiln gas 60 moving along the longitudinal direction of the separation cooling pipe 12 become a mixed gas into the separation cooling pipe 12. A swirl flow 64 is formed. The swirling shaft of the swirling flow 64 and the central shaft of the separation cooling pipe 12 substantially coincide with each other. That is, the swirling flow 64 uses the substantially central axis of the separation cooling pipe 12 as the swirling axis. It is preferable that the swirling shaft of the swirling flow 64 completely coincides with the central shaft of the separation cooling pipe 12. However, it is not essential that the two match exactly. For example, even if the swirling axis of the swirling flow 64 is deviated from the central axis of the separation cooling pipe 12 to the extent that a swirling flow 64 is formed so that 70% by mass or more of the total dust can be recovered from the mixed gas by the recovery unit 30. good. The mixed gas moves along the longitudinal direction (right direction in FIG. 2) of the separation cooling pipe 12 while swirling inside the separation cooling pipe 12. That is, the mixed gas forms a spiral swirling flow inside the separation cooling pipe 12 and moves from the upstream side to the downstream side of the separation cooling pipe 12.

The introduction path 13 may be provided with a damper for adjusting the flow velocity of the cooling gas between the introduction fan 14 and the separation cooling pipe 12, or on the upstream side of the introduction fan 14. Thereby, the amount of the cooling gas introduced can be appropriately adjusted according to the operating condition of the kiln 50, the concentration of dust, the amount of bleed air of the kiln gas, and the like.

In FIG. 2, the introduction direction of the cooling gas 62 in the introduction path 13 and the tangential direction of the separation cooling pipe 12 are the same, but these directions do not necessarily have to be the same. That is, the introduction direction of the cooling gas 62 in the introduction path 13 may deviate from the tangential direction of the separation cooling pipe 12 within a range in which the swirling flow 64 can be formed. For example, when viewed in FIG. 2, the cooling gas 62 may be introduced into the separation cooling pipe 12 so as to go in the lower right direction.

As shown in FIGS. 1 and 2, the recovery unit 30 is connected to the separation cooling pipe 12 (expansion unit 12A) on the downstream side of the introduction path 13, and at least a part of the dust centrifuged by the swirling flow 64. To collect. The collection unit 30 includes a hopper 32 that is connected to the lower side of the side portion of the separation cooling pipe 12 and forms a flow path for dropping dust downward, and a dust collection unit 34 below the hopper 32. Examples of the dust collector 34 include a bug filter, an electrostatic precipitator, a cyclone, and the like. As shown in FIG. 1, the dust collected by the dust collecting unit 34 is supplied to the kiln tail 52 as a cement raw fuel via the flow path 36. The supply destination of the dust is not limited to the kiln tail 52, and may be directly supplied to a cement firing device such as a calcining furnace or a preheater cyclone, or may be supplied to a raw material mill or a blending silo in the raw material blending process. May be good.

FIG. 3 is a view when the separation cooling pipe 12 side is viewed from the cross section taken along line III-III of FIG. 2 (diameter cross section of the first discharge passage 21). As shown in FIG. 3, the hopper 32 is provided so as to extend in the tangential direction of the separation cooling pipe 12 (expansion portion 12A) along the swirling direction of the swirling flow 64. As a result, the swirling flow 64 is stably maintained, and the mixed gas containing a large amount of dust, which flows through the portion near the outer peripheral portion of the separation cooling pipe 12, is easily guided to the hopper 32 by the swirling flow 64. As a result, the dust 68 is smoothly centrifuged, and it is possible to sufficiently suppress the mixing of volatile substances such as chlorides in the dust 68.

The dust 68 is a solid content contained in the kiln gas 60 at the stage of being introduced into the separation cooling pipe 12 (before cooling), and is different from the volatile content, so that it can be used as a raw material for cement. .. The dust 68 has a particle size larger than that of the volatile particles deposited in the separation cooling pipe 12 by cooling the kiln gas 60. Therefore, the dust 68 is collected by the collecting unit 30 by centrifugation by the swirling flow 64.

In FIG. 3, the introduction path 13 and the hopper 32 extend in the vertical direction in FIG. 3, but at least one of the introduction path 13 and the hopper 32 may be inclined with respect to the vertical direction and is in the horizontal direction. It may be extended to. Further, the introduction path 13 and the hopper 32 may be inclined in the depth direction of FIG. However, the hopper 32 preferably extends downward from the viewpoint of improving the efficiency of dust recovery.

As shown in FIG. 1, the dust collecting unit 34 provided on the downstream side of the hopper 32 is provided with a second suction device 42 that sucks the mixed gas flowing through the separation cooling pipe 12 via the collecting unit 30. There is. The second suction device 42 is not particularly limited, and examples thereof include ordinary blowers such as a sirocco fan and a turbo fan. By providing the second suction device 42, the dust contained in the mixed gas flowing through the separation cooling pipe 12 can be smoothly recovered by the recovery unit 30. Therefore, the dust accumulated on the bottom portion 12a near the recovery portion 30 of the separation cooling pipe 12 shown in FIG. 2 is sufficiently reduced.

Since the bleed air device 100 can sufficiently reduce the dust accumulated on the bottom portion 12a, the swirling flow 64 is less likely to be disturbed, and the dust can be centrifuged with sufficiently high accuracy. Therefore, it is possible to prevent volatile components such as chlorides from being mixed into the dust collected by the recovery unit 30, and it is possible to increase the efficiency of chlorine extraction.

The second suction device 42 may have a suction gas amount adjusting unit for adjusting the suction gas amount. As a result, the amount of gas to be sucked is adjusted according to the operating condition of the kiln 50, the amount of air extracted from the kiln gas, the concentration of dust in the kiln gas, the amount of volatile matter deposited, and the ratio of dust and volatile matter contained in the mixed gas. can do. The gas sucked by the second suction device 42 may be supplied to the introduction fan 14 through a flow path (not shown). The introduction fan 14 may introduce the gas as a cooling gas from the introduction path 13 into the separation cooling pipe 12.

The recovery unit 30 may have a damper as a means for adjusting the amount of suction gas sucked by the second suction device 42. As a result, for example, even when the wind speed of the cooling gas from the introduction path 13 is slow and the swirling speed of the swirling flow 64 is slow, the dust contained in the kiln gas 60 is collected by the wind force generated by the suction from the second suction device 42. It can be fully recovered. Therefore, it is possible to sufficiently suppress the accumulation of dust on the bottom portion 12a of the separation cooling pipe 12.

As shown in FIG. 2, in the expansion portion 12A of the separation cooling pipe 12, at least a part of the dust 68 is separated from the mixed gas, and the separation gas 66 having a dust concentration lower than that of the mixed gas is generated. By having the expansion portion 12A in the separation cooling pipe 12, dust can be sufficiently and smoothly separated by centrifugation from the mixed gas. Then, the amount of volatile matter contained in the dust collected by the collection unit 30 can be sufficiently reduced.

Returning to FIG. 1, on the downstream side of the separation cooling pipe 12, a volatile matter removing unit 20 for removing the volatile matter precipitated in the separation cooling pipe 12 from the separation gas is provided. The volatile matter removing unit 20 has a cooler 24 and a dust collecting unit 26 in this order from the upstream side. The separation cooling pipe 12 and the cooler 24 are connected via the first discharge passage 21, and the cooler 24 and the dust collector 26 are connected via the second discharge passage 22. The first discharge passage 21 composed of a cylindrical tube body is arranged concentrically with the separation cooling pipe 12 (expansion portion 12A). The inner diameter of the first discharge passage 21 is smaller than the inner diameter of the expansion portion 12A, and the end portion of the first discharge passage 21 on the separation cooling pipe 12 side is inserted into the expansion portion 12A of the separation cooling pipe 12, and two It has a heavy pipe structure (see FIG. 2). By adopting such a double tube structure, the dust can be centrifuged more smoothly.

As the cooler 24, a normal air-cooled type or water-cooled type can be used depending on the heat resistance of the dust collecting unit 26. The second discharge passage 22 is composed of a normal cylindrical pipe body. As the dust collecting unit 26, a dust collecting unit 26 capable of capturing volatile substances such as chloride can be appropriately used. Examples of the dust collector 26 include a bug filter, an electrostatic precipitator, a cyclone, and the like. Since the separation gas introduced into the volatile component removing unit 20 has a high temperature, a cyclone can be preferably used. As the dust collector 26, one type of the above-mentioned example may be used alone, or two or more types may be used in combination.

As shown in FIGS. 2 and 3, the separated gas 66 obtained by recovering the dust from the mixed gas flows toward the cooler 24 while swirling the first discharge path 21 connected to the expansion portion 12A. That is, the separated gas 66 also becomes a spiral swirling flow and flows through the first discharge path 21. The separated gas 66 is cooled to a predetermined temperature range by the cooler 24 shown in FIG. 1, and then flows through the second discharge passage 22 and is introduced into the dust collecting unit 26. The dust collector 26 captures volatile components such as chloride contained in the separated gas. The volatile matter is gaseous in the kiln tail 52, but is a component that is precipitated by cooling in the separation cooling pipe 12, and contains chlorides such as potassium chloride and sodium chloride, for example.

Returning to FIG. 1, the first suction device 40 is connected to the dust collecting unit 26. The first suction device 40 sucks the separated gas from the separation cooling pipe 12 via the volatile matter removing unit 20. The kiln gas 60 is introduced into the separation cooling pipe 12 by suction by the first suction device 40 and the second suction device 42. The first suction device 40 is not particularly limited, and examples thereof include ordinary blowers such as a sirocco fan and a turbo fan. By providing the first suction device 40, the volatile matter such as chloride precipitated in the mixed gas flowing through the separation cooling pipe 12 can be recovered by the volatile matter removing unit 20.

The first suction device 40 may have a suction gas amount adjusting unit for adjusting the suction gas amount. As a result, the amount of gas to be sucked is adjusted according to the operating condition of the kiln 50, the amount of air extracted from the kiln gas, the concentration of dust in the kiln gas, the amount of volatile matter deposited, and the ratio of dust and volatile matter contained in the mixed gas. can do. The gas sucked by the first suction device 40 may be supplied to the introduction fan 14 through a flow path (not shown). The introduction fan 14 may introduce the gas as a cooling gas from the introduction path 13 into the separation cooling pipe 12.

The bleed air device 100 includes a first suction device 40 on the downstream side of the volatile matter removing unit 20, and a second suction device 42 on the downstream side of the collection unit 30. By providing the two suction devices in this way, the cooling gas or mixed gas kiln tail 52 that may occur due to fluctuations in the operating condition of the kiln 50, fluctuations in the flow rate of the cooling gas introduced from the introduction path 13, and the like. The backflow of gas can be sufficiently suppressed. Such an bleed air device 100 and a cement firing device including the bleed air device 100 can continue to operate stably.

Chloride obtained by cooling kiln gas has adhesiveness. Therefore, when the concentration of chloride (volatile matter) in the solid content contained in the separation gas becomes high, the amount of chloride adhering to the inner walls of the first discharge passage 21, the cooler 24, and the second discharge passage 22 increases. As a result, the dust collecting portion 26 tends to be clogged and the piping tends to be clogged. From the viewpoint of reducing the amount of chloride adhered, the separation gas introduced from the separation cooling pipe 12 into the volatile matter removing unit 20 preferably contains a certain amount of dust. By containing dust having a larger particle size together with the adhesive chloride, clogging and clogging can be sufficiently suppressed.

Since the bleed air device 100 includes the first suction device 40 and the second suction device 42, the amount of dust contained in the separated gas can be adjusted by adjusting the amount of these suction gases individually or in conjunction with each other. Can be done. For example, the amount of dust contained in the separated gas can be increased by increasing the amount of suction gas of the first suction device 40 and reducing the amount of suction gas of the second suction device 42. As a result, the chlorine concentration of the solid content contained in the separation gas can be lowered. The chlorine concentration based on the solid content contained in the separation gas introduced into the volatile component removing unit 20 is preferably about 10 to 30% by mass, and more preferably about 15 to 20% by mass. As a result, the operation of the bleeding device 100 can be continued more stably by suppressing clogging, clogging, etc., while maintaining the chlorine bleeding efficiency sufficiently high.

An example of controlling the amount of suction gas of the second suction device 42 will be described below. When the operating condition of the kiln 50 fluctuates and the dust concentration in the kiln tail gas increases, it is introduced into the separation cooling pipe 12 in order to maintain the chlorine concentration in the solid content introduced into the volatile matter removing unit 20. It is necessary to increase the flow rate of the cooling gas to increase the amount of dust collected by the collection unit 30. Here, if the flow rate of the cooling gas is increased too much, a part of the cooling gas may flow back to the kiln tail 52 side, which may cause a temperature drop of the kiln tail 52. Therefore, in such a case, the flow rate of the cooling gas is adjusted and the suction gas amount of the second suction device 42 is controlled to be increased. As a result, the swirling flow 64 in the separation cooling pipe 12 is strengthened, and the amount of dust collected by the collection unit 30 can be increased.

On the contrary, when the dust concentration in the kiln tail gas decreases, the separation cooling pipe 12 prevents the chlorine concentration in the solid content of the separation gas from becoming too high in the volatile matter removing unit 20. It is necessary to reduce the flow rate of the cooling gas introduced into the recovery unit 30 to reduce the amount of dust recovered by the recovery unit 30. Here, when the flow rate of the cooling gas decreases, the swirling flow 64 becomes weak, and there is a concern that the amount of dust accumulated on the bottom 12a of the separation cooling pipe 12 increases. Therefore, in such a case, the flow rate of the cooling gas is adjusted and the suction gas amount of the second suction device 42 is increased. As a result, the strength of the swirling flow 64 in the separation cooling pipe 12 is maintained. Therefore, the chlorine concentration in the solid content of the separated gas can be maintained within a predetermined range while suppressing the accumulation of dust on the bottom portion 12a.

The above-mentioned control example may be performed by a control system as shown in FIG. The control system 70 of FIG. 4 has a dust amount calculation unit 74 that calculates the amount of dust contained in the kiln gas extracted into the separation cooling pipe 12, and a first suction unit according to the dust amount calculated by the dust amount calculation unit 74. A control unit 71 for controlling the amount of suction gas of the device 40 and the second suction device 42 and the flow rate of the cooling gas introduced from the introduction path 13 is provided. The dust amount calculation unit 74 receives a signal associated with the dust concentration from the dust concentration measuring unit 72 for measuring the dust concentration of the kiln gas extracted to the separation cooling pipe 12, and the extraction amount of the kiln gas extracted to the separation cooling pipe 12. A signal associated with the bleeding amount of kiln gas is input from the bleeding amount measuring unit 73 for measuring. The dust amount calculation unit 74 calculates the dust amount based on these input signals, and outputs a signal associated with the dust amount to the control unit 71.

The control unit 71 calculates the amount of suction gas by the first suction device 40 and the second suction device 42 and the flow rate of the cooling gas introduced from the introduction path 13 based on the input signal from the dust amount calculation unit 74. 1 Control processing of the suction device 40 and the second suction device 42 is performed. The control unit 71 outputs a control signal based on each calculation result to the first suction gas amount adjustment unit 75, the second suction gas amount adjustment unit 76, and the cooling gas amount adjustment unit 77. The first suction gas amount adjusting unit 75 and the second suction gas amount adjusting unit 76 adjust the suction gas amount by the first suction device 40 and the second suction device 42, and the cooling gas adjusting unit 77 cools the suction gas from the introduction path 13. The amount of gas introduced is adjusted.

The dust concentration measuring unit 72 is, for example, a normal measuring instrument for measuring the solid content in the gas, and the bleed air amount measuring unit 73 is a normal flow meter. The dust amount calculation unit 74 and the control unit 71 include, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like.

The dust amount calculation unit 74 stores table data or a function for calculating the dust amount from the bleed air amount and the dust concentration of the kiln gas, and calculates the dust amount based on these. The control unit 71 stores table data or a function that associates the dust amount with the flow rate of the cooling gas and the suction gas amount, and a control signal for adjusting the flow rate of the cooling gas and the suction gas amount of the gas based on these is stored. Is output. The first suction gas amount adjusting unit 75 and the second suction gas amount adjusting unit 76 may be, for example, a damper, and are rotation adjusters of the rotating machine provided in the first suction device 40 and the second suction device 42. May be good.

By providing the control system 70 as shown in FIG. 4, when the bleed amount of the kiln gas and / or the dust concentration in the kiln gas fluctuates, the bleeding device 100 automatically maintains a high chlorine bleeding efficiency. The operation can be continued stably. The control system is not limited to that of FIG. 4, and for example, the dust amount may be calculated using other parameters of the cement firing apparatus or may be a predicted value. Further, the dust amount calculation unit 74 and the control unit 71 may be configured by separate hardware, or may be included in the same hardware.

Further, for example, since the color of the volatile matter captured in the dust collecting unit 26 becomes whiter as the chlorine concentration increases, the above control may be performed based on the whiteness of the captured volatile matter. For example, based on the correlation equation between the whiteness of the volatile matter and the chlorine concentration obtained experimentally in advance and the measurement result of the whiteness of the volatile matter captured by the dust collector 26, the first suction device 40 and the first suction device 40 and the first 2. The amount of suction gas may be adjusted by the suction device 42, and the amount of cooling gas introduced from the introduction path 13 may be adjusted. By adjusting the whiteness of the volatile matter within a predetermined range, the chlorine concentration of the volatile matter can be controlled within a predetermined range. The whiteness may be measured based on the brightness of the image using, for example, an image recognition unit provided with a CCD camera, or may be measured using a commercially available color difference meter.

The air extraction device 100 has at least the flow rate of the cooling gas, the suction gas amount of the first suction device 40, and the suction gas amount of the second suction device 42, depending on the amount of dust contained in the kiln gas extracted into the separation cooling pipe 12. It may be provided with a control unit for adjusting one. Examples of the control unit include those capable of performing any of the above-mentioned controls, but the control unit is not limited to the above-mentioned ones.

FIG. 5 is a diagram showing a modified example of the bleed air device according to the above embodiment. The bleed air device 102 according to this modification includes an ejector 42A as a second suction device in the collection unit 30. Air is pumped from the push-in fan 35 to the ejector 42A. When the pumped air is compressed by the ejector 42A, a negative pressure is generated in the ejector 42A. By using the ejector 42A as the second suction device, the dust can be collected without providing the dust collecting unit and the mechanical transport device for transferring the dust collected by the dust collecting unit. That is, the ejector 42A can suck the mixed gas of the separation cooling pipe 12 and collect the dust in parallel. Therefore, the configuration of the bleed air device 102 becomes compact, and restrictions on the installation location can be reduced.

Since air is pumped to the ejector 42A, the dust can be cooled in the ejector 42A. Further, by connecting a pipe to the ejector 42A, dust can be pumped to an arbitrary place.

The ejector 42A may be arranged below the hopper 32 or may be attached to the side wall of the hopper 32. Further, the ejector 42A may be connected to the upper part of the hopper 32, and air may be pumped against gravity to collect dust. Dust can be sufficiently recovered by appropriately setting the speed of the air pumped from the push-in fan 35 according to the position where the ejector 42A is arranged.

By setting the suction direction of the ejector 42A to a suitable range with respect to the hopper 32, it is possible to sufficiently suppress the accumulation of dust on the bottom 12a of the separation cooling pipe 12. In addition, the swirling flow 64 is less likely to be disturbed, and the dust can be centrifuged with sufficiently high accuracy.

The suction pressure of the ejector 42A is calculated by Bernoulli's theorem (Equation (1)).
^{P = ρ × V 2/2} ··· (1)
In the formula (1), P is the suction pressure, ρ is the density of the fluid, and V is the fluid velocity.

The suction pressure is proportional to the square of the wind speed (air volume). The air volume of the push-in fan 35 can be adjusted by using an air volume adjusting damper. The suction gas amount and suction pressure pressure by the ejector 42A may be adjusted by the opening degree of the air volume adjusting damper, or may be adjusted by controlling the rotation speed of the push-in fan by inverter control.

The dust recovered by the ejector 42A may be supplied to the kiln tail 52 as a cement raw fuel via the flow path 36A as shown in FIG. The supply destination of the dust is not limited to the kiln tail 52, and may be directly supplied to a cement firing device such as a calcining furnace or a preheater cyclone, or may be supplied to a raw material mill or a blending silo in the raw material blending process. May be good.

The flow velocity of the pumping fluid containing dust and air flowing through the flow path 36A is preferably 15 m / sec or more. When this flow velocity is 15 m / sec or more, it is possible to sufficiently suppress the accumulation of dust in the pipes constituting the flow path 36A. On the other hand, when the flow velocity of the pumping fluid exceeds 40 m / sec, the pressure loss in the pipe becomes large, and the power consumption by the pushing fan 35 tends to increase. From this point of view, it is preferable to set the flow velocity of the pumping fluid in the flow path 36A to 15 to 40 m / sec. The amount of dust sucked in such a range may be adjusted to adjust the chlorine concentration of the solid content contained in the separation gas.

The size of the small diameter portion of the ejector 42A may be determined, for example, by calculating the amount of suction gas when the speed of the pumping fluid is about 20 m / sec by the above formula (1) and based on the calculation result.

In this modification, the ejector 42A is connected to the hopper 32, but the ejector 42A is connected to the pipe connected to the separation cooling pipe 12 without installing the hopper 32, and the mixed gas is directly passed through the pipe. You may inhale.

The kiln gas bleeding method can be carried out by operating the kiln gas bleeding device 100 (102) based on the above description. An example of the method of extracting the kiln gas is an air extraction step of extracting the kiln gas 60 from the kiln tail 52 of the kiln 50 to the separation cooling pipe 12, and separating and cooling by introducing the cooling gas into the separation cooling pipe 12 and joining the kiln gas 60. The dust 68 contained in the mixed gas is centrifuged and the dust 68 is collected by the introduction step of generating the swirling flow 64 containing the kiln gas and the cooling gas and the swirling flow 64 having the substantially central axis of the pipe 12 as the swirling axis. In the recovery step of obtaining the separated gas 66 having less dust than the mixed gas while recovering to 30, the separated gas 66 is sucked by the first suction device 40 and introduced into the volatile matter removing unit 20, and the separated cooling pipe 12 It has a removal step of removing the volatile matter precipitated in the above from the separation gas. Then, in the removing step, the separated gas is sucked by the first suction device 40 through the volatile matter removing unit 20, and in the recovery step, the mixed gas of the separation cooling pipe 12 is sucked by the second suction device 42.

The temperature of the kiln gas near the kiln tail 52 of the kiln 50 extracted in the bleeding step is, for example, 900 to 1300 ° C. At such a temperature, volatile components such as chlorine brought in from the cement raw material are in the form of gas. In the bleeding step, the kiln gas 60 containing dust and gaseous volatile matter is bleeded into the separation cooling pipe 12. In the introduction step, a cooling gas (for example, air) is mixed with the kiln gas 60 and cooled in the separation cooling pipe 12. As a result, the gaseous volatile matter becomes a solid content. The particle size of the solid content containing chloride is, for example, 1 μm or less. On the other hand, the kiln gas 60 contains dust as a raw material for cement. This dust has a particle size of about several μm to 100 μm, which is larger than the solid content of the volatile matter.

The dust having a large particle size moves to the vicinity of the inner wall surface of the separation cooling pipe 12 by the centrifugal action of the swirling flow 64. The dust 68 that has moved to the vicinity of the inner wall surface is led out to the collection unit 30 connected to the downstream side of the separation cooling pipe 12 from the introduction path 13, and the dust is collected. In this way, in the recovery step, the dust contained in the mixed gas is recovered by centrifugation. On the other hand, since the solid content containing chloride has a smaller particle size than the dust, it is contained in the separated gas without being centrifuged. In the removing step, the separated gas containing the solid content is introduced into the volatile content removing unit 20 by suction of the first suction device 40. The solid content contained in the separated gas is separated from the gas and recovered in the volatile content removing unit 20. In this way, volatile matter and dust can be recovered.

The bleeding method is at least one of the flow rate of the cooling gas, the suction gas amount of the first suction device 40, and the suction gas amount of the second suction device 42, depending on the amount of dust contained in the kiln gas extracted in the bleeding step. May have an adjustment step to adjust. Such an adjustment step may be performed by a control system as shown in FIG. Each of the above steps can be performed according to the description of the bleed air device 100 described above.

Although some embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the separation cooling pipe does not have to extend in the horizontal direction, and may be inclined so that the downstream side faces upward or downward. Further, the separation cooling pipe may be bent or curved as long as a swirling flow of the mixed gas is formed. In the volatile matter removing part, the separated gas does not have to form a swirling flow. The recovery unit and the volatile matter removing unit are not limited to the above-described configuration. For example, the volatile matter removing unit does not have to have a cooler 24.

Provided is a kiln gas bleeding device capable of stably continuing operation while maintaining high chlorine bleeding efficiency. Further, a kiln gas bleeding method capable of stably continuing operation while maintaining a high chlorine bleeding efficiency is provided.

12 ... Separation cooling pipe, 12A ... Expansion part, 12a ... Bottom, 13 ... Introduction path, 14 ... Introduction fan, 20 ... Volatile removal part, 21 ... First discharge path, 22 ... Second discharge path, 24 ... Cooler , 26 ... dust collecting part, 30 ... collecting part, 32 ... hopper, 34 ... dust collecting part, 35 ... pushing fan, 36, 36A ... flow path, 40 ... first suction device, 42 ... second suction device, 42A ... Ejector, 50 ... kiln, 52 ... kiln butt, 54 ... flue, 60 ... kiln gas, 62 ... cooling gas, 64 ... swirling flow, 66 ... separation gas, 68 ... dust, 70 ... control system, 74 ... dust amount calculation unit , 71 ... Control unit, 72 ... Dust concentration measurement unit, 73 ... Extraction amount measurement unit, 75 ... First suction gas amount adjustment unit, 76 ... Second suction gas amount adjustment unit, 77 ... Cooling gas adjustment unit, 100 ... Extraction Device.

Claims (8)

A separation cooling pipe that cools the kiln gas by mixing the kiln gas extracted from the kiln and a cooling gas, and separates at least a part of dust from the mixed gas containing the kiln gas and the cooling gas to obtain a separation gas.
An introduction path for introducing the cooling gas into the separation cooling pipe so that a swirling flow of the mixed gas having a substantially central axis of the separation cooling pipe as a swirling axis is generated.
A collection unit that is connected to the side of the separation cooling pipe on the downstream side of the introduction path and collects at least a part of the dust that is centrifuged by the swirling flow.
A volatile matter removing unit that is connected to the end of the separation cooling pipe on the downstream side of the introduction path and opposite to the end on the kiln side, and removes the volatile matter deposited in the separation cooling pipe from the separation gas. When,
A first suction device provided on the downstream side of the volatile matter removing portion and sucking the separated gas of the separation cooling pipe through the volatile matter removing portion.
A second suction device provided on the downstream side of the recovery unit or on the recovery unit to suck the mixed gas of the separation cooling pipe is provided .
The introduction path, the recovery section, and the volatile matter removing section are connected to the separation cooling pipe in this order from the upstream side.
The volatile component removing unit is a kiln gas bleeding device arranged concentrically with the separation cooling pipe. The recovery unit has a flow path extending in the tangential direction of the separation cooling pipe along the swirling direction of the swirling flow when viewed from the downstream side to the upstream side of the separation cooling pipe, and the second suction The kiln gas bleeding device according to claim 1, wherein the vessel is connected to the downstream side of the flow path. At least one of the flow rate of the cooling gas, the suction gas amount of the first suction device, and the suction gas amount of the second suction device, depending on the amount of the dust contained in the kiln gas extracted into the separation cooling pipe. The kiln gas bleeding device according to claim 1 or 2, which is configured to adjust. The kiln gas bleeding device according to any one of claims 1 to 3, wherein the second suction device provided in the collecting unit is an ejector. A bleeding process that bleeds kiln gas from the kiln into a separate cooling pipe,
An introduction step of introducing a cooling gas into the separation cooling pipe and merging it with the kiln gas to generate a swirling flow of a mixed gas containing the kiln gas and the cooling gas, with the substantially central axis of the separation cooling pipe as the swirling axis. ,
A recovery step of centrifuging the dust contained in the mixed gas by the swirling flow to recover the dust in a recovery unit and obtaining a separated gas having less dust than the mixed gas.
It has a removal step of introducing the separated gas into the volatile matter removing unit and removing the volatile matter precipitated in the separated cooling pipe from the separated gas.
In the removal step, the separated gas of the separation cooling pipe is sucked by the first suction device through the volatile matter removing portion.
In the recovery step, a method of extracting the kiln gas by sucking the mixed gas of the separation cooling pipe with a second suction device. When viewed from the downstream side to the upstream side of the separation cooling pipe, in the recovery step, the separation cooling is performed by a flow path in which the mixed gas extends in the tangential direction of the separation cooling pipe along the swirling direction of the swirling flow. The method for extracting kiln gas according to claim 5, which is derived from a pipe. At least one of the flow rate of the cooling gas, the suction gas amount of the first suction device, and the suction gas amount of the second suction device is set according to the amount of the dust contained in the kiln gas extracted in the air extraction step. The method for extracting kiln gas according to claim 5 or 6, which comprises an adjusting step for adjusting. The method for extracting a kiln gas according to any one of claims 5 to 7, wherein the second suction device that sucks the mixed gas in the recovery step is an ejector.

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